calculation of the standard molal thermodynamic properties as a function of temperature and...

PII S0016-7037(01)00694-9

Calculation of the standard molal thermodynamic properties as a function of temperatureand pressure of some geochemically important organic sulfur compounds§

LAURENT RICHARD*Department of Earth & Planetary Science, University of California, Berkeley, CA 94720-4767, USA

(Received November 15, 2000;accepted in revised form July 5, 2001)

Abstract—The standard molal thermodynamic properties and heat capacity power function coefficients ofmore than 100 organic sulfur compounds in the crystalline, liquid, and/or gas state have been calculated bycombining regressions of experimental data reported in the literature together with carbon number systematicsand group additivity algorithms. The compounds for which these calculations have been made include carbondisulfide, branched thiols, cyclic thiols, aromatic thiols,n-alkyl sulfides, branched sulfides, cyclic sulfides(including long-chainn-alkylthiolanes andn-alkylthianes), aromatic sulfides,n-alkyl disulfides, alkylthio-phenes, methylated benzothiophenes and dibenzothiophenes, and thianthrene. In addition, the correspondingproperties and coefficients for 12 sulfur-containing groups in the crystalline, liquid, and/or gas states have beenretrieved, which can be used to estimate the standard molal thermodynamic properties and heat capacity powerfunction coefficients of sulfur-rich kerogens or other high molecular weight organic sulfur compounds ofgeochemical interest.Copyright © 2001 Elsevier Science Ltd

1. INTRODUCTION

Sulfur is the third major constituent of sedimentary organicmatter after carbon and hydrogen (Krein, 1993), and is ofenvironmental concern as the combustion of the sulfur presentin fossil fuels is in part responsible for the acid rain problem(Orr and Sinninghe Damste´, 1990). In that respect, understand-ing the behavior of organic sulfur in petroleum systems is offundamental importance. Extensive research has been carriedout over the past fifteen years to determine the nature of theorganic sulfur compounds present in a variety of geologicalenvironments, as well as to understand the processes responsi-ble for their formation and diagenetic evolution. Comprehen-sive reviews on this subject have been published by Orr andSinninghe Damste´ (1990), Sinninghe Damste´ and de Leeuw(1990), and Krein (1993).

In order to quantify the processes responsible for the forma-tion of organic sulfur compounds and their chemical evolutionduring maturation, as well as to evaluate the extent to whichmetastable equilibrium states may be established between or-ganic sulfur compounds, aqueous fluids, hydrogen sulfide, andminerals in hydrocarbon reservoir and source rocks, knowledgeof the thermodynamic properties of these organic sulfur com-pounds as a function of temperature and pressure is required.As part of an effort made in this laboratory to develop acomprehensive and internally consistent thermodynamic data-base for organic compounds of biogeochemical interest, thestandard molal thermodynamic properties and heat capacitypower function coefficients of more than 100 organic sulfurcompounds in the crystalline, liquid, or gas state have beencalculated by regressing experimental data together with car-bon number systematics and group additivity relations. Thedetails of the regression calculations are presented below, fol-

lowing a brief description of the organic sulfur compoundscommonly encountered in kerogen, bitumen or crude oils, anda summary of the thermodynamic relations used in the calcu-lations.

2. OCCURRENCE, FORMATION, ANDTRANSFORMATIONS OF ORGANIC SULFUR

COMPOUNDS IN PETROLEUM SYSTEMS

The organic sulfur content of crude oils and bitumens ishighly variable, from less than 0.05 to more than 14 weightpercent (Orr and Sinninghe Damste´, 1990). Sulfur-rich crudeoils are thought to be generated from sulfur-rich kerogens(Gransch and Posthuma, 1974; Orr, 1986), for which the atomicS/C ratios can be as high as 0.05 to 0.09 (Orr and SinningheDamste, 1990). As pointed out by Sinninghe Damste´ and deLeeuw (1990), the sulfur content in fossil fuels is generally toohigh to be accounted for by the sulfur content of biochemicalmolecules. Furthermore, the chemical forms under which or-ganic sulfur occurs in biomolecules differ markedly from theorganic sulfur compounds identified in crude oils, bitumens,and kerogens. A rapid comparison can be made from thestructures shown in Table 1 for some S-containing biochemicalcompounds and organic sulfur compounds commonly found infossil fuels. It seems now currently accepted that organic sulfurcompounds form during early diagenetic processes, by reactionof bacterially produced hydrogen sulfide (or other reducedinorganic sulfur species) with unsaturated bonds or oxygenatedfunctional groups of the biologic precursors of sedimentaryorganic matter (Vairavamurthy and Mopper, 1987; SinningheDamsteet al., 1989a), an idea originally proposed by Ivlev etal. (1973) based on thermodynamic considerations.

Sulfur in kerogen is mainly present in heterocyclic rings, andas sulfide or disulfide linkages (Tissot and Welte, 1984). In-vestigations of kerogen structures using degradation techniqueshave indicated that the sulfur-containing units in sulfur-richkerogens are related to the organic sulfur compounds identifiedin the associated bitumens (see below). These units may in-

* Author to whom correspondence should be addressed ([email protected]).§ This paper is dedicated to Professor Harold C. Helgeson on theoccasion of his seventieth birthday.

Pergamon

Geochimica et Cosmochimica Acta, Vol. 65, No. 21, pp. 3827–3877, 2001Copyright © 2001 Elsevier Science LtdPrinted in the USA. All rights reserved

0016-7037/01 $20.00� .00

3827

Table 1. Idealized chemical structures of sulphur-containing biochemical compounds and organic sulfur compounds identified in bitumens orimmature oils, and in conventional crude oils.

3828 L. Richard

clude alkylthiophene and alkylbenzothiophene moieties, aswell as cyclic sulfides bound to the kerogen matrix throughacyclic sulfide linkages (Sinninghe Damste and de Leeuw,1990). Sterane and hopane moieties attached to the matrix of asulfur-rich kerogen through such aliphatic sulfide linkages havealso been reported (Richnow et al., 1992).

Immature crude oils and bitumens have been shown tocontain more than one thousand previously unidentified organicsulfur compounds, with structures resembling those of theso-called biomarkers.1 These compounds, the structures ofsome of which are shown in Table 1, include: 2,5-di-n-alky-

lthiacyclopentanes (or -alkylthiolanes), 2,6-di-n-alkylthiacy-clohexanes (or -alkylthianes), 2,5-di-n-alkylthiophenes, 2,4-di-n-alkylbenzo[b]thiophenes, isoprenoid thiolanes, isoprenoidthiophenes, isoprenoid bithiophenes, isoprenoid benzo[b]thio-phenes, isoprenoid thienyl thiolanes, thiolane and thiophenesteranes, polycyclic sulfides, a C35 thienyl hopane, and twoseries of benzothiophene hopanoids.

With increasing maturation, the organic sulfur compoundscharacteristic of immature oils and bitumens progressively dis-appear, the predominant organic sulfur species in mature crudeoils becoming simpler, lower molecular weight compoundssuch as those shown in Table 1. Most of the compounds shownin Table 1 for mature crude oils have been identified during theAmerican Petroleum Institute Research Project 48. During thisproject, more than 200 individual compounds were identified,including 53 thiols, 110 sulfides, 4 disulfides, and 37 thiophenic

1 Payzant et al. (1983), Valisolalao et al. (1984), Brassel et al. (1986),Schmid et al. (1987), Sinninghe Damste and de Leeuw (1987), Sin-ninghe Damste et al. (1986, 1987, 1989b), van Kaam-Peters et al.(1995).

Table 1. (Continued)

3829Thermodynamic properties of organic sulfur compounds

compounds (Rall et al., 1972). In addition to these low molec-ular weight compounds, series of bicyclic, tricyclic and tetra-cyclic sulfides with isoprenoid side chains have been identifiedin petroleum samples from various locations by Payzant et al.(1986). Another class of compounds which has received con-siderable attention in recent years is the aromatic sulfur com-pounds, i.e., the alkylbenzothiophenes and alkyldibenzothio-phenes, which are commonly used as maturity indicators (e.g.,Radke and Willsch, 1994; Chakhmakhchev et al., 1997). Theformation of these organic sulfur compounds during diagenesisis not yet completely understood (Chakhmakhchev et al.,1997), nor is the change in the distribution of organic sulfurcompounds from bitumens to crude oils with increasing matu-rity (Orr and Sinninghe Damste, 1990). Such questions may beaddressed using theoretical calculations, for which the thermo-dynamic properties are retrieved below.

3. THERMODYNAMIC RELATIONS

The standard state adopted in the present study for solid andliquid organic species is one of unit activity of the thermody-namic components of the stoichiometric solids and pure liquidsat any pressure and temperature. The standard state for gasescalls for unit activity of the pure hypothetical ideal gas at 1 barand any temperature.

The equilibrium constant K of any reaction at a given tem-perature T and pressure P is obtained from the relation

K � exp��GR

�

RT, (1)

where R is the gas constant, T the absolute temperature, and�GR

° the standard molal Gibbs free energy of the reaction,defined as

�GR� � �

i

ni,r �Gi� , (2)

where ni,r represents the stoichiometric reaction coefficient ofthe ith species involved in the rth reaction, and �Gi

° stands forthe apparent standard molal Gibbs free energy of formation ofthe ith species, which can be expressed in general notation for�Gi

° � �G° as

�G� � �Gf� � �GP,T

� � GPr,Tr

� �, (3)

where �Gf° refers to the standard molal Gibbs free energy of

formation of the species from the elements in their stable format the reference pressure (Pr) and temperature (Tr) of 1 bar and298.15 K, and GP,T

° � GPr ,Tr

° stands for the difference in thestandard molal Gibbs free energy of the species at the pressureP and temperature T of interest, and those at Pr and Tr. Theparenthetical term in Eqn. 3 can be expressed as a function oftemperature and pressure by writing

GP,T� � GPr,Tr

� � �SPr,Tr

� �T � Tr� � �Tr

T

CPr

� dT

� T�Tr

T

CPr

� d ln T � �Pr

P

V� dP, (4)

where SPr ,Tr

° corresponds to the standard molal entropy of thespecies at the reference pressure and temperature, CPr

° stands forits isobaric standard molal heat capacity at the reference pres-sure, and V° represents its standard molal volume at the tem-perature of interest.

It has been shown by Helgeson et al. (1998) that the tem-perature dependence of the standard molal heat capacity of bothcrystalline and liquid organic compounds other than alcoholscan be accurately described with the Maier-Kelley power func-tion (Maier and Kelley, 1932), which can be written as

CPr

� � a � bT �c

T2 , (5)

where a, b, and c stand for temperature-independent coeffi-cients for the species of interest. The corresponding heat ca-pacity expression for ideal gas organic species other thanmethane has the form (Helgeson et al., 1998)

CPr

� � a � bT � cT2. (6)

The b coefficient in Eqn. 5 and 6 is always positive, but the aand c coefficients may adopt positive or negative values. Sub-stituting separately Eqn. 5 and 6 in Eqn. 4 and integrating theheat capacity terms leads to

GP,T� � GPr,Tr

� � �SPr,Tr

� �T � Tr� � a�T � Tr � T ln� T

Tr��

� � �c � bTr2 T��T � Tr�

2

2Tr2 T � � �

Pr

P

V� dP (7)

for organic crystals and liquids, and

GP,T� � GPr,Tr

� � �SPr,Tr

� �T � Tr� � a�T � Tr � T ln� T

Tr��

�b

2�T � Tr�

2 � c�T3 � 3TTr2 � 2Tr

3

6 � � �Pr

P

V� dP (8)

for organic gases. As a consequence of the standard stateadopted in the present study for organic gases, V° � 0 and thevolume integral in Eqn. 8 reduces to zero. It has been shown byHelgeson et al. (1978) that the standard molal volumes (V°) ofminerals are essentially independent of temperature and pres-sure under crustal conditions due to the compensating effects ofthermal expansion and compressibility. Although organic crys-tals are both significantly more compressible and expansiblethan minerals, high-pressure measurements reported by Vaidyaand Kennedy (1971) for several organic solids have indicated adecrease in the compressibility with increasing molecular vol-ume. The organic solids which are of geochemical interest arekerogens (i.e., macromolecules), and should therefore be ex-pected to be much less compressible than simpler, lower mo-lecular volume organic crystals. Thermal expansion data forhigh molecular weight organic solids are too few in number todetermine accurately if the effects associated with increasingtemperature and pressure do actually compensate for each otheralong geotherms. However, such a compensation is indirectlysupported by the fact that the melting temperatures of highmolecular weight hydrocarbons can be predicted within 5°C at

3830 L. Richard

pressures up to 3000 bars by adopting in a first approximationan hypothesis of constant volume for high molecular weightsolids (Richard and Helgeson, 2001), which is consistent with

V� � VPr,Tr

� . (9)

In the case of organic liquids, the volume integral in Eqn. 7must be calculated with the aid of an equation of state. TheParameters From Group Contributions (PFGC) equation ofstate (Cunningham, 1974; Majeed and Wagner, 1986) has beenadopted by Helgeson et al. (1998) for calculating the standardmolal volumes (V°) of organic liquids as a function of temper-ature and pressure. Revised parameter values for the PFGCequation of state allow to calculate the standard molal volumesof organic liquids within 5% of their experimental counterpartsfor conditions of temperature and pressure characteristic ofsedimentary basins (Richard and Helgeson, 2001). Errors of theorder of 10% or more may occur at high temperatures and lowpressures, or at low temperatures and high pressures (Majeedand Wagner, 1986; Richard and Helgeson, 2001). The PFGCequation of state parameters required to calculate the standardmolal volumes of liquid organic sulfur compounds will bepublished in Richard and Helgeson (2001). Values of the stan-dard molal thermodynamic properties and heat capacity powerfunction coefficients of 116 organic sulfur compounds in thecrystalline, liquid, and/or gas states have been calculated bycombining regression of experimental data reported in theliterature together with carbon number systematics and groupadditivity algorithms. The details of the retrieval calculationsare summarized below.

4. REGRESSION CALCULATIONS

Calorimetric studies have been reported in the literaturefor � 60 organic sulfur compounds. The molecular weights,liquid (or in some instances crystal) densities at 25°C, andtransition, melting, and boiling properties of these compoundsare listed in Table 2. Most of the experimental informationavailable for their thermodynamic properties has been includedin the regression calculations, which resulted in the standardmolal thermodynamic properties and heat capacity power func-tion coefficients listed in Tables 3–5 for 8 crystalline, 67 liquid,and 62 gaseous organic sulfur compounds. The properties andcoefficients listed in Tables 3–5 have been combined togetherwith group stoichiometry relations to calculate those of crys-talline, liquid and gas sulfur-containing groups, which can beused to estimate the standard molal thermodynamic propertiesand heat capacity power function coefficients of high molecularweight organic sulfur compounds for which no experimentalinformation is available in the literature (see below).

As indicated in the footnotes to Tables 3 and 4, the standardmolal enthalpies of formation (�Hf

°) from the elements in theirstable form at 25°C and 1 bar of several crystalline and liquidorganic sulfur compounds have been recalculated in the presentstudy from the original combustion data using the followingprocedure. The combustion of a sulfur-containing compoundCaHbSc in a calorimetric bomb leads to the production of CO2

gas and an aqueous solution of sulfuric acid according to(Good, 1972)

CaHbSc�l or cr� � �a � b/4 � 3c/ 2� O2� g� � �nc � c

� b/ 2� H2O�l � ¡ a CO2� g� � c �H2SO4 � nH2O�l ��, (10)

where (cr), (l), and (g) refer to the crystalline, liquid, and gasstates, respectively. The standard molal enthalpies of combus-tion (�Hc

°) at 25°C associated with reaction (10) were firstrecalculated from the measured standard changes in internalenergy (�Ec

°) reported in cal � g�1 in the original combustionstudies, the molecular weights listed in Table 2, and the relation

�Hc� � M�Ec

� � �nRTr , (11)

where M is the molecular weight, �n the change in the numberof moles of gas in reaction (10), R the gas constant, and Tr isthe reference temperature of 298.15 K. The standard molalenthalpies of formation (�Hf

°) of the organic sulfur compoundswere then obtained from

�Hf� �CaHbSc�l or cr�� a �Hf

� �CO2� g��

� c �Hf� �H2SO4 � nH2O�l �� nc � c � b/ 2� �Hf

� �H2O�l ��

� �Hc� (12)

using values of �Hf° for CO2(g), H2O(l) and H2SO4 � nH2O(l)

taken from Wagman et al. (1982), and combined with values oftheir standard molal entropies (S°) at 25°C and 1 bar taken fromthe literature or estimated in the present study (see below) tocalculate the standard molal Gibbs free energies of formationlisted in Tables 3 and 4 according to

�Gf� � �Hf

� � T�Sf�, (13)

where �Sf° is the standard molal entropy of formation of the

organic sulfur compound CaHbSc from the elements in theirstable form at 25°C and 1 bar, which is given by

�Sf� � SCaHbSc�cr or l �

� � aSC�cr,graphite�

� � �b/ 2� SH2(g)

� �cSS�cr,rhombic�

� ,

(14)

where C(cr,graphite), H2(g), and S(cr,rhombic) refer to the stableforms of carbon, hydrogen and sulfur at 25°C and 1 bar.

The procedures followed to retrieve the standard molal ther-modynamic properties and heat capacity power function coef-ficients of all the organic sulfur compounds listed in Tables 3–5are described separately for each compound or class of com-pounds in the following section.

4.1. Carbon Disulfide

The vapor pressure curve and critical point of carbon disul-fide (I)2 are represented in Figure 1, together with the vaporpressure curve for saturated liquid and gas H2O. It can be seenin this figure that the vapor pressure curve for CS2 falls in theliquid-phase region of the system H2O.

The standard molal thermodynamic properties and heat ca-pacity power function coefficients for CS2 liquid and gas arelisted in Tables 4 and 5, respectively. The standard molal

2 All organic sulfur compounds considered in the regression calcula-tions are indexed in the text by Roman numerals, which correspond tothe idealized structural representations shown for these compounds inAppendix 1.


Table 2. Summary of physical properties of organic sulfur compounds considered in the present study.

Compound Formula Mol. Wt.a,b Densityc,d Tt,Pr

e �Ht,Pr

f Tm,Pr

e �Hm,Pr

f Tv,Pr

e �Hv,Pr

f

Carbon disulfide CS2 76.143 1.255g — — 161.11h 1049.0h 319.37i 6390i

Branched thiols2-Propanethiol C3H8S 76.162 0.80862 112.5j 12.63j 142.64j 1371j 325.72j 6670j

2-Butanethiol C4H10S 90.188 0.82478 — — 133.02k 1548k 358.14k 7312k

2-Methyl-1-propanethiol C4H10S 90.188 0.82929 — — 128.31l 1190.8l 361.65l 7412l

2-Methyl-2-propanethiol C4H10S 90.188 0.79470 151.6m 972.0m 274.42m 593.2m 337.38m 6797m

157.0m 154.9m

199.4m 232.0m

2-Methyl-1-butanethiol C5H12S 104.215 0.84194 392.15n 8077o

2-Methyl-2-butanethiol C5H12S 104.215 0.82117 159.1p 1907.1p 169.37p 145.4p 372.28p 7497p

3-Methyl-1-butanethiol C5H12S 104.215 0.83159 — — 139.64q 1770q 391.49n

3-Methyl-2-butanethiol C5H12S 104.215 0.83604 144.47q 1688q 146.05q 145.1q 382.91n

2,2-Dimethyl-1-propanethiol C5H12S 104.215 0.8253 206.2r 376.83n

2-Methyl-2-pentanethiol C6H14S 118.241 0.82209s 398.18n

2,3-Dimethyl-2-butanethiol C6H14S 118.241 0.83997s 399.28n

Cyclic thiolsCyclopentanethiol C5H10S 102.199 0.95048t — — 155.39t 1871.6t 405.32t 8443t

Cyclohexanethiol C6H12S 116.225 0.94402s — — 189.64u 2390u 431.95n 8858v

Aromatic thiolsBenzenethiol C6H6S 110.178 1.07273 128w 40w 258.27w 2736w 442.30w 9543v

Phenylmethanethiol C7H8S 124.204 1.05143s 467-8x

n-Alkyl sulfides2-Thiapropane C2H6S 62.135 0.84228 — — 174.86y 1908.4y 310.49y 6453z

2-Thiabutane C3H8S 76.162 0.83677 — — 167.23aa 2333aa 339.81aa 7055aa

2-Thiapentane C4H10S 90.188 0.83739 — — 160.17ab 2369ab 368.70ab 7667ab

2-Thiahexane C5H12S 104.215 0.83777 — — 175.30ac 2976ac 396.57ac 8239v

2-Thiaheptane C6H14S 118.241 0.8389 179r 418.2v 8941v

2-Thiaoctane C7H16S 132.268 0.8393 206.7r 444r

2-Thianonane C8H18S 146.295 0.8398 209.9r 468r

2-Thiadecane C9H20S 160.321 0.8403 231r 491r

2-Thiaundecane C10H22S 174.348 0.8409 238r 513r

3-Thiapentane C4H10S 90.188 0.83118 — — 169.21ad 2845ad 365.26ad 7591ad

3-Thiahexane C5H12S 104.215 0.83224 — — 156.10ac 2529ac 391.65ac 8184v

4-Thiaheptane C6H14S 118.241 0.83312 — — 170.44ac 2902ac 415.98ac 8748v

4-Thiaoctane C7H16S 132.268 439.2ac

5-Thianonane C8H18S 146.295 0.83442af — — 198.13ac 4643ac 462.06ac

5-Thiadecane C9H20S 160.3216-Thiaundecane C10H22S 174.348 0.8409ag 221.9ah 502.0ai

Branched sulfides3-Methyl-2-thiabutane C4H10S 90.188 0.82484 — — 171.65aj 2236aj 357.98ac 7338aj

3,3-Dimethyl-2-thiabutane C5H12S 104.215 0.82051 — — 190.84ak 2011ak 372.04ak 7523ak

2-Methyl-3-thiapentane C5H12S 104.215 0.8199 150.96r 380.53r 7825v

2,4-Dimethyl-3-thiapentane C6H14S 118.241 0.81029 — — 195.07u 2489u 393.16n 8078v

2,2-Dimethyl-3-thiapentane C6H14S 118.241 0.8161 184.20r 393.56r 7946al

2,6-Dimethyl-4-thiaheptane C8H18S 146.295 0.8363ag 167.7ah 445–6am

2,2,4,4-Tetramethyl-3-thiapentane C8H18S 146.295 0.82207s 263–5x 422.2v 7949v

2,8-Dimethyl-5-thianonane C10H22S 174.348 0.8323ag 489.2x

Cyclic sulfidesThiacyclopropane C2H4S 60.119 1.007 164.r 328.09an 6980r

Thiacyclobutane C3H6S 74.146 1.01469 176.7ao 159.8ao 199.91ao 1971.4ao 368.13ao 7700r

Thiacyclopentane C4H8S 88.172 0.99376 — — 176.98ap 1757.2ap 394.28ap 8279ap

Thiacyclohexane C5H10S 102.199 0.98090 201.4aq 262.4aq 292.25aq 585.2aq 414.91aq 8599aq

240.02aq 1858.3aq

Thiacycloheptane C6H12S 116.225 0.9907ar 273.7as 446as

2-Methylthiacyclopentane C5H10S 102.199 0.95043 — — 172.39q 2121.4q 405.62n

3-Methylthiacyclopentane C5H10S 102.199 0.9585 — — 192.00q 2478.6q 411.48n

Cyclopentyl-1-thiaethane C6H12S 116.225 0.93769s 165.0q 214q 169.85q 2205q 429.38n

Aromatic sulfidesDiphenyl sulfide C12H10S 186.274 1.107at — — 257.80at 3340.7at 569x

Phenyl-1-thiaethane C7H8S 124.204 1.0535 — — 256.44q 3545.8q 467.46n

Poly(thio-1,4-phenylene) (C6H4S)m 108.162 1.405au 363av 593av 2067aw

(Continued)

3832 L. Richard

Table 3. Standard molal thermodynamic properties and heat capacity power function coefficients of crystalline organic sulfur compounds.

Compound Formula �Gf°a,f �Hf

°a S°b V°c Cp°b,g ab bd 10�3 ce 105

Aromatic thiolsBenzenethiol C6H6S 32541 12311h 41.74h 84.5i 36.60 �1.98j 125.7j 0.98j

Aromatic sulfidesDiphenyl sulfide C12H10S 69924 33639h 58.59h 146.5i 54.27 �5.24k 196.0k 0.95k

Phenyl-1-thiaethane C7H8S 35347 6353h 44.95h 99.5i 40.50 �1.99l 139.2l 0.88l

Poly(thio-1,4-phenylene) (C6H4S)m 38912 23733m 27.45m 83.5i 25.90 �3.02m 93.4m 0.95m

ThiophenicsThiophene C4H4S 29081 17252h 35.94h 59.7i 23.11 11.78n 38.0n 0.00n

Benzo[b]thiophene C8H6S 45264 24392o 42.33p 96.8i 38.65 �4.13q 143.5q 0.00q

Dibenzo[b,d]thiophene C12H8S 58605 28716o 48.81r 133.9i 47.42 �0.13s 159.5s 0.00s

Thianthrene C12H8S2 73776 43502t 55.18u 150.2v 52.66 12.07w 145.4w �2.45w

a Cal mol�1. b Cal mol�1K�1. c Cm3 mol�1. d Cal mol�1 K�2. e Cal K mol�1. f Calculated from Eqn. 13. g Calculated from Eqn. 5. h Calculatedfrom the value at Tm in the manner described in the text. i Calculated using the volume increments algorithm of Immirzi and Perini (1977). j Generatedby regression of experimental heat capacity data reported by Scott et al. (1956). k Generated by regression of experimental heat capacity data reportedby Steele et al. (1995). l Generated by regression of experimental heat capacity data reported by Messerly et al. (1974). m Estimated using groupcontributions generated in the present study (see text) or taken from Richard and Helgeson (1998). n Coefficients corresponding to the straight linedrawn in Figure 40. o Recalculated from combustion data reported by Good (1972). p Finke et al. (1954). q Generated by regression of experimentalheat capacity data reported for crystal I by Finke et al. (1954). r Chirico et al. (1991b). s Generated by regression of experimental heat capacity datareported by Chirico et al. (1991b). t Recalculated from combustion data reported by Hubbard et al. (1954). u Steele et al. (1993). v Calculated fromthe density and molecular weight listed in Table 2. w Generated by regression of experimental heat capacity data reported by Steele et al. (1993).


Compound Formula Mol. Wt.a,b Densityc,d Tt,Pr

e �Ht,Pr

f Tm,Pr

e �Hm,Pr

f Tv,Pr

e �Hv,Pr

f

n-Alkyl disulfides2,3-Dithiabutane C2H6S2 94.201 1.05687 — — 188.44ax 2197.1ax 382.91ax 8050r

3,4-Dithiahexane C4H10S2 122.254 0.98815 — — 171.64ay 2247.7ay 427.14ay 9010r

3,4-Dithiaheptane C5H12S2 136.281 446.9al 9388al

4,5-Dithiaoctane C6H14S2 150.307 0.95489 — — 187.66az 3300az 469.01az 10020r

5,6-Dithiadecane C8H18S2 178.361 0.9342 202.r 504.4r

6,7-Dithiadodecane C10H22S2 206.414 0.9182 214.r 537.0r

ThiophenicsThiophene C4H4S 84.141 1.05884 112ba smallba 234.95ba 1215.5ba 357.32ba 7522ba

138ba smallba

171.6ba 152.4ba

2-Methylthiophene C5H6S 98.167 1.01419 163bb 0bb 209.79bb 2263bb 385.72bb 8103bb

3-Methylthiophene C5H6S 98.167 1.01644 — — 204.19bc 2518bc 388.60bc 8186bc

2,5-Dimethylthiophene C6H8S 112.194 0.9799 — — 210.58bd 1957.7bd 409.9be 8569be

2-Isopropylthiophene C7H10S 126.220 0.9633 426.be 8974be

Benzo[b]thiophene C8H6S 134.199 1.165bf 261.6bg 719.6bg 304.50bh 2826.8bh 494.05bh 10550bi

Dibenzo[b,d]thiophene C12H8S 184.258 1.182bf — — 371.82bj 5188.3bj 604.61bj 13150bk

Thianthrene C12H8S2 216.324 1.44bl — — 429.58bm 6585.8bm 639.26bm

a G mol�1. b Calculated using the 1995 values for the atomic weights of the elements (Coplen, 1996). c G cm�3. d Unless indicated otherwise, thevalues listed in this column are liquid densities at 25°C and 1 atmosphere listed in the TRC Thermodynamic Tables (1986). e K. f Cal mol�1. g Goodet al. (1961). h Brown and Manov (1937). i Waddington et al. (1962). j McCullough et al. (1954a). k McCullough et al. (1958). l Scott et al. (1958).m McCullough et al. (1953a). n Osborn and Douslin (1966). o Hossenlopp and Scott (1981). p Scott et al. (1962a). q Messerly et al. (1974). r TRCThermodynamic Tables (1986). s Good (1972). t Berg et al. (1961). u Messerly et al. (1967). v Majer and Svoboda (1985). w Scott et al. (1956).x Handbook of Data on Organic Compounds (1989). y Osborne et al. (1942). z McCullough et al. (1957). aa Scott et al. (1951). ab Scott et al. (1957).ac McCullough et al. (1961). ad Scott et al. (1952a). ae White et al. (1952). af Morris et al. (1960). ag Value at 20°C reported in the Handbook ofChemistry and Physics (1992). ah Handbook of Chemistry and Physics (1992). ai Experimental value cited by Girelli (1953). aj McCullough et al.(1955). ak Scott et al. (1962b). al Dreisbach (1961). am Dictionary of Organic Compounds (1982). an Guthrie et al. (1952). ao Scott et al. (1953).ap Hubbard et al. (1952). aq McCullough et al. (1954b). ar Value at 20°C given by Sunner (1949). as Sunner (1949). at Steele et al. (1995). au Chen andJiang (1980). av Smirnova et al. (1996). aw Value cited by Cheng et al. (1987). ax Scott et al. (1950). ay Scott et al. (1952b). az Hubbard et al. (1958b).ba Waddington et al. (1949). bb Pennington et al. (1956). bc McCullough et al. (1953b). bd Carlson and Westrum (1965). be Dreisbach (1955). bf Densityvalue for the solid reported by Good (1972). bg Finke et al. (1954). bh Chirico et al. (1991a). bi Interpolated from values at rounded temperaturesreported by Chirico et al. (1991a). bj Chirico et al. (1991b). bk Interpolated from values at rounded temperatures reported by Chirico et al. (1991b).bl Larson et al. (1984). bm Steele et al. (1993).


Table 4. Standard molal thermodynamic properties and heat capacity power function coefficients of liquid organic sulfur compounds.


°a S°b V°c CP° b,g ab bd 10�3 ce 105

Carbon disulfide CS2 15583 21370h 36.10i 60.7j 18.07k 17.77l 1.0l —

Branched thiols2-Propanethiol C3H8S �1290 �25237m 56.39m 94.2j 34.75 14.94n 57.9n 2.263n

2-Butanethiol C4H10S 496 �30865m 64.13m 109.3j 40.94 17.34o 68.7o 2.770o

2-Methyl-1-propanethiol C4H10S �65 �31324m 64.47m 108.8j 41.09 17.08p 70.2p 2.741p

2-Methyl-2-propanethiol C4H10S �544 �33282m 59.51m 113.5j 41.85 25.25q 53.5q 0.579q

2-Methyl-1-butanethiol C5H12S 1720 �36953m 72.21m 123.8j 45.75 23.83r 68.1r 1.442r

2-Methyl-2-butanethiol C5H12S 1770 �38382m 67.25m 126.9j 47.36 18.40s 84.7s 3.293s

3-Methyl-1-butanethiol C5H12S 1199 �37474m 72.21m 125.3j 47.95 19.12t 86.1t 2.809t

3-Methyl-2-butanethiol C5H12S 879 �38277m 70.59m 124.7j 47.57 17.93t 86.8t 3.344t

2,2-Dimethyl-1-propanethiol C5H12S 1003 �39369m 66.51m 126.3j 45.79 19.12u 81.8u 2.028u

2-Methyl-2-pentanethiol C6H14S 3033 �44532m 74.99m 143.8j 54.28 20.47u 98.0u 4.080u

2,3-Dimethyl-2-butanethiol C6H14S 3602 �44345m 73.71m 140.8j 52.19 20.78u 96.2u 2.428u

Cyclic thiolsCyclopentanethiol C5H10S 11276 �21311v 61.39w 107.5j 39.49 9.62x 87.5x 3.362x

Cyclohexanethiol C6H12S 8711 �33475y 61.80z 123.1j 46.04 14.05aa 94.7aa 3.342aa

Aromatic thiolsBenzenethiol C6H6S 32099 15301ab 53.25ac 102.7j 41.41 21.68ad 57.8ad 2.224ad

Phenylmethanethiol C7H8S 32939 8727y 60.99ae 118.1j 48.21 23.04ae 73.9ae 2.788ae

n-Alkyl sulfides2-Thiapropane C2H6S 1411 �15631m 46.94m 74.2af 28.06 13.1ag 43.0ag 1.900ag

2-Thiabutane C3H8S 1808 �22029m 56.76m 90.9af 34.49 15.2ag 55.9ag 2.330ag

2-Thiapentane C4H10S 3070 �28179m 64.50m 107.5af 40.99 17.2ag 69.4ag 2.750ag

2-Thiahexane C5H12S 4336 �34328m 72.24m 124.2af 47.61 19.1ag 83.6ag 3.190ag

2-Thiaheptane C6H14S 5598 �40478m 79.98m 140.8af 53.83 20.5ag 98.1ag. 3.630ag

2-Thiaoctane C7H16S 6863 �46628m 87.72m 157.5af 60.79 22.3ag 113.8ag 4.050ag

2-Thianonane C8H18S 8126 �52777m 95.46m 174.2af 67.97 24.8ag 127.8ag 4.506ag

2-Thiadecane C9H20S 9391 �58927m 103.20m 190.8af 75.17 28.23ag 137.5ag 5.293ag

2-Thiaundecane C10H22S 10657 �65076m 110.93m 207.5af 82.46 31.88ag 146.7ag 6.080ag

3-Thiapentane C4H10S 2202 �28427m 66.58m 108.0ah 40.99 17.2ag 69.4ag 2.750ag

3-Thiahexane C5H12S 3467 �34577m 74.32m 124.9ah 47.61 19.1ag 83.6ag 3.190ag

4-Thiaheptane C6H14S 4729 �40727m 82.06m 141.8ah 53.83 20.5ag 98.1ag 3.630ag

4-Thiaoctane C7H16S 5995 �46876m 89.80m 158.7ah 60.79 22.3ag 113.8ag 4.050ag

5-Thianonane C8H18S 7257 �53026m 97.54m 175.7ah. 67.97 24.8ag 127.8ag 4.506ag

5-Thiadecane C9H20S 8523 �59175m 105.28m 192.6ah 75.17 28.23ag 137.5ag 5.293ag

6-Thiaundecane C10H22S 9785 �65325m 113.02m 209.5ah 82.46 31.88ag 146.7ag 6.080ag

Branched sulfides3-Methyl-2-thiabutane C4H10S 2230 �29503m 62.88m 109.3j 41.20 15.84ai 73.6ai 3.041ai

3,3-Dimethyl-2-thiabutane C5H12S 2976 �37548m 66.00m 127.0j 47.80 18.81aj 86.6aj 2.817aj

2-Methyl-3-thiapentane C5H12S 2626 �35901m 72.70m 127.1j 48.25 17.17u 90.2u 3.721u

2,4-Dimethyl-3-thiapentane C6H14S 3048 �43375m 78.82m 145.9j 55.53 27.81aa 86.3aa 1.765aa

2,2-Dimethyl-3-thiapentane C6H14S 3372 �43946m 75.82m 144.9j 54.72 20.88u 99.9u 3.604u

2,6-Dimethyl-4-thiaheptane C8H18S 5497 �55550m 94.98m 178.0j 64.21 24.92u 122.0u 2.594u

2,2,4,4-Tetramethyl-3-thiapentane C8H18S 9918 �54087m 85.06m 174.9j 67.54 24.52u 130.2u 3.734u

2,8-Dimethyl-5-thianonane C10H22S 8025 �67849m 110.46m 209.5j 77.06 28.22u 150.7u 3.474u

Cyclic sulfidesThiacyclopropane C2H4S 22557 12411ak 38.84al 59.7j 20.09 3.53am 46.5am 2.400am

Thiacyclobutane C3H6S 24418 6304an 44.72ao 73.1j 27.05 7.43am 57.5am 2.200am

Thiacyclopentane C4H8S 9213 �17147an 49.67ap 88.7j 33.55 11.33am 68.5am 1.600am

Thiacyclohexane C5H10S 10051 �25288aq 52.16ar 104.2j 39.05 15.23am 79.5am 0.100am

Thiacycloheptane C6H12S 15385 �26953ak 61.29as 118.7at 42.51 19.13am 90.5am �3.200am

2-Methylthiacyclopentane C5H10S 8355 �25054y 58.63au 107.5j 41.07 15.25t 81.1t 1.456t

3-Methylthiacyclopentane C5H10S 9417 �24300y 57.60au 106.6j 41.06 13.22t 85.7t 2.032t

Cyclopentyl-1-thiaethane C6H12S 13669 �26599y 68.23au 123.9j 46.12 12.77t 99.5t 3.274t

Aromatic sulfidesDiphenyl sulfide C12H10S 69362 37502av 73.43av 168.3j 65.43 29.72aw 113.8aw 1.579aw

Phenyl-1-thiaethane C7H8S 34735 10332y 60.35au 117.9j 49.21 21.28t 80.9t 3.390t

n-Alkyl disulfides2,3-Dithiabutane C2H6S2 1163 �15894m 54.56m 89.5ax 35.02 23.9ay 32.0ay 1.400ay

2,3-Dithiapentane C3H8S2 1557 �22292m 64.38m 106.4ax 42.05 26.2ay 46.8ay 1.690ay

3,4-Dithiahexane C4H10S2 1954 �28690m 74.20m 123.3ax 48.87 28.5ay 60.5ay 2.070ay

3,4-Dithiaheptane C5H12S2 3216 �34840m 81.94m 140.3ax 55.66 30.9ay 73.3ay 2.580ay

4,5-Dithiaoctane C6H14S2 4482 �40989m 89.68m 157.2ax 62.72 33.3ay 86.6ay 3.200ay

4,5-Dithianonane C7H16S2 5744 �47139m 97.42m 174.1ax 69.83 35.9ay 98.8ay 3.980ay

5,6-Dithiadecane C8H18S2 7009 �53289m 105.16m 191.0ax 74.56 38.6ay 109.2ay 4.800ay

5,6-Dithiaundecane C9H20S2 8272 �59438m 112.90m 208.0ax 83.84 42.25ay 118.4ay 5.587ay

6,7-Dithiadodecane C10H22S2 9537 �65588m 120.64m 224.9ax 91.22 45.98ay 127.7ay 6.374ay

(Continued)

3834 L. Richard

enthalpy of formation (�Hf°) for CS2 liquid in Table 4 was

recalculated from the combustion data reported by Good et al.(1961) in the manner described above, and combined with thestandard molal enthalpy of vaporization at 25°C and 1 bar(�Hv

°) of 6610 cal mol�1 given by these authors to obtain thevalue of �Hf

° listed in Table 5 for CS2 gas from

�Hf� (gas) � �Hf

� (liquid) � �Hv� . (15)

The values for the standard molal entropies (S°) at 25°C and 1bar of CS2 liquid and gas in Tables 4 and 5 have been takenfrom the literature, and used to calculate the standard molalGibbs free energies (�Gf

°) from Eqn. 13 using values for theentropies of the elements taken from Cox et al. (1989). Thestandard molal volume (V°) at 25°C and 1 bar of CS2 liquid inTable 4 was calculated from the density and molecular weightlisted in Table 2.

The experimental heat capacity data for CS2 liquid repre-sented by the symbols in Figure 2 have been linearly regressedwith the equation

CP� � a � bT, (16)

which resulted in the values of a and b in Table 4 and thestraight line passing through the symbols in Figure 2. Regres-sion of the ideal gas heat capacity data depicted as symbols inFigure 2 with Eqn. 6 resulted in the a, b, and c coefficientsgiven in Table 5 for CS2 gas and the curve shown in Figure 2.

4.2. Branched Thiols

Calorimetric and vapor pressure measurements have beenreported in the literature for eleven branched thiols, including2-propanethiol (II), 2-butanethiol (III), 2-methyl-1-propane-thiol (IV), 2-methyl-2-propanethiol (V), 2-methyl-1-butane-thiol (VI), 2-methyl-2-butanethiol (VII), 3-methyl-1-butane-thiol (VIII), 3-methyl-2-butanethiol (IX), 2,2-dimethyl-1-propanethiol (X), 2-methyl-2-pentanethiol (XI), and 2,3-dimethyl-2-butanethiol (XII)3. Vapor pressure curves for these

3 McCullough et al. (1953a, 1954a, 1958), Hubbard and Waddington(1954), Hubbard et al. (1954, 1958a), Scott et al. (1958, 1962a), Osbornand Douslin (1966), Good (1972), Messerly et al. (1974), Hossenloppand Scott (1981).



°a S°b V°c CP° b,g ab bd 10�3 ce 105

ThiophenicsThiophene C4H4S 28664 19029az 43.30ba 79.5j 29.61 12.78bb 51.4bb 1.338bb

2-Methylthiophene C5H6S 27443 10747bc 52.22bd 96.8j 35.79 16.27be 59.3be 1.636be

3-Methylthiophene C5H6S 27086 10381bf 52.19bg 96.6j 36.00 15.22bh 62.3bh 1.960bh

2,5-Dimethylthiophene C6H8S 27013 2465bi 58.49bj 114.5j 42.61 16.74bk 74.7bk 3.210bk

2-Isopropylthiophene C7H10S 29078 �2830y 66.41bl 131.0j 47.40 20.13bl 85.6bl 1.558bl

Benzo[b]thiophene C8H6S 45324 27180bm 51.48bm 116.0bn 44.91 25.45bo 68.8bo �0.934bo

Dibenzo[b,d]thiophene C12H8S 59558 33155bm 60.50bm 152.5bp 59.07 40.85bq 83.6bq �5.964bq

Thianthrene C12H8S2 77050 48539bm 61.09bm 163.5br 68.41 39.19bs 98.0bs 0.000bs

a Cal mol�1. b Cal mol�1 K�1. c Cm3 mol�1. d Cal mol�1 K�2. e Cal K mol�1. f Calculated from Eqn. 13. g Calculated from Eqn. 5. h Recalculatedfrom combustion data reported by Good et al. (1961)—see text. i Brown and Manov (1937)j Calculated from the density and molecular weight listedin Table 2. k Calculated from Eqn. 16. l Generated by linear regression of experimental heat capacity data reported by Brown and Manov (1937).m Calculated from algorithms given by Domalski and Hearing (1993). n Generated by regression of experimental heat capacity data reported byMcCullough et al. (1954a). o Generated by regression of experimental heat capacity data reported by McCullough et al. (1958). p Generated byregression of experimental heat capacity data reported by Scott et al. (1958). q Generated by regression of experimental heat capacity data reportedby McCullough et al. (1953a). r Estimated using group contributions taken from Helgeson et al. (1998). s Generated by regression of experimentalheat capacity data reported by Scott et al. (1962a). t Generated by regression of experimental heat capacity data reported by Messerly et al. (1974).u Estimated using group contributions generated in the present study (see text) or taken from Helgeson et al. (1998). v Recalculated from combustiondata reported by Berg et al. (1961). w Berg et al. (1961). x Generated by regression of experimental heat capacity data reported by Berg et al. (1961).y Recalculated from combustion data reported by Good (1972). z Messerly et al. (1967). aa Generated by regression of experimental heat capacity datareported by Messerly et al. (1967). ab Recalculated from combustion data reported by Scott et al. (1956). ac Scott et al. (1956). ad Generated byregression of experimental heat capacity data reported by Scott et al. (1956). ae Calculated by adding to the properties and coefficients for benzenethiolgroup contributions given by Helgeson et al. (1998) for the –CH2– group of ethylbenzene. af Calculated from Eqn. 31. ag Read off the smooth curvein Figure 17. ah Calculated from Eqn. 32. ai Generated by regression of experimental heat capacity data reported by McCullough et al. (1955).aj Generated by regression of experimental heat capacity data reported by Scott et al. (1962b). ak Recalculated from the heat of combustion reportedby Sunner (1963). al Guthrie et al. (1952). am Read off the straight line or curve in Figure 26. an Recalculated from combustion data reported byHubbard et al. (1954). ao Scott et al. (1953). ap Hubbard et al. (1952). aq Recalculated from the combustion data reported by McCullough et al. (1954b).ar McCullough et al. (1954b). as Value estimated by adding to the So value for thiacyclohexane the difference between the So values for cyclohexaneand cycloheptane given by Helgeson et al. (1998). at Calculated from Eqn. 39. au Messerly et al. (1974). av Steele et al. (1995). aw Generated byregression of experimental heat capacity data reported by Steele et al. (1995). ax Calculated from Eqn. 43. ay Read off the smooth curve in Figure 34.az Recalculated from combustion data reported by Waddington et al. (1949). ba Waddington et al. (1949). bb Generated by regression of experimentalheat capacity data reported by Waddington et al. (1949). bc Recalculated from combustion data reported by Pennington et al. (1956). bd Penningtonet al. (1956). be Generated by regression of experimental heat capacity data reported by Pennington et al. (1956). bf Recalculated from combustion datareported by McCullough et al. (1953b). bg McCullough et al. (1953b). bh Generated by regression of experimental heat capacity data reported byMcCullough et al. (1953b). bi Estimated using Eqn. 46. bj Carlson and Westrum (1965). bk Generated by regression of experimental heat capacity datareported by Carlson and Westrum (1965). bl Estimated using Eqn. 47. bm Calculated from the value at Tm in the manner described in the text.bn Calculated from Eqn. 48. bo Generated by regression of experimental heat capacity data reported by Chirico et al. (1991a). bp Calculated from Eqn.49. bq Generated by regression of experimental heat capacity data reported by Chirico et al. (1991b). br Calculated from Eqn. 50. bs Generated byregression of experimental heat capacity data reported by Steele et al. (1993).


Table 5. Standard molal thermodynamic properties and heat capacity power function coefficients of gas organic sulfur compounds.

Compound Formula �G°fa,e �H°f

a Sob C°Pb,f ab bc 10�3 cd 105

Carbon disulfide CS2 16093 28064g 56.84h 10.91 8.03i 12.0i �0.619i

Branched thiols2-Propanethiol C3H8S �760 �18231j 78.11j 22.97 3.45k 74.8k �3.131k

2-Butanethiol C4H10S 1780 �22622j 87.47j 28.52 3.63l 95.5l �4.029l

2-Methyl-1-propanethiol C4H10S 2012 �22643j 86.62j 28.31 2.58m 99.6m �4.461m

2-Methyl-2-propanethiol C4H10S 524 �25884j 80.74j 28.92 2.44n 102.2n �4.485n

2-Methyl-1-butanethiol C5H12S 4552 �27034j 95.98j 33.17 1.75o 120.1o �4.939o

2-Methyl-2-butanethiol C5H12S 2961 �29725j 92.29j 34.31 3.24p 119.3p �5.062p

3-Methyl-1-butanethiol C5H12S 4012 �27574j 95.98j 33.47 2.36o 118.8o �4.845o

3-Methyl-2-butanethiol C5H12S 3158 �29152j 93.55j 33.75 2.64q 118.5q �4.751q

2,2-Dimethyl-1-propanethiol C5H12S 3372 �30065j 89.77j 33.40 1.24q 123.7q �5.307q

2-Methyl-2-pentanethiol C6H14S 4960 �34656j 101.65j 39.71 2.77q 142.2q �6.135q

2,3-Dimethyl-2-butanethiol C6H14S 5881 �34716j 98.36j 39.56 2.28q 142.2q �5.758q

Cyclic thiolsCyclopentanethiol C5H10S 13755 �11381r 86.38s 25.78 �6.09t 122.4t �5.203t

Cyclohexanethiol C6H12S 11816 �22805u 87.17v 31.82 �6.07w 142.2w �5.066w

Aromatic thiolsBenzenethiol C6H6S 35612 26941x 80.51y 25.16 �3.18z 110.9z �5.316z

Phenylmethanethiol C7H8S 37858 22257u 89.87aa 30.78 �3.22aa 132.7aa �6.263aa

n-Alkyl sulfides2-Thiapropane C2H6S 1695 �8970j 68.33j 17.69 5.72ab 44.8ab �1.559ab

2-Thiabutane C3H8S 2484 �14508j 79.72j 22.70 4.79ac 68.0ac �2.655ac

2-Thiapentane C4H10S 4484 �19438j 89.08j 28.04 4.75ad 87.6ad �3.181ad

2-Thiahexane C5H12S 6484 �24369j 98.44j 33.06 4.28ae 108.4ae �3.987ae

2-Thiaheptane C6H14S 8484 �29300j 107.80j 38.47 3.75ae 131.6ae �5.084ae

2-Thiaoctane C7H16S 10484 �34230j 117.16j 43.87 3.21ae 154.8ae �6.181ae

2-Thianonane C8H18S 12484 �39161j 126.52j 49.27 2.67ae 178.0ae �7.278ae

2-Thiadecane C9H20S 14484 �44092j 135.87j 54.67 2.13ae 201.2ae �8.375ae

2-Thiaundecane C10H22S 16484 �49022j 145.23j 60.08 1.59ae 224.4ae �9.472ae

3-Thiapentane C4H10S 4095 �20045j 88.35j 27.94 4.32af 90.0af �3.617af

3-Thiahexane C5H12S 5684 �24976j 99.08j 33.08 3.86ae 112.0ae �4.693ae

4-Thiaheptane C6H14S 8095 �29907j 107.07j 38.48 3.32ae 135.2ae �5.790ae

4-Thiaoctane C7H16S 9684 �34837j 117.80j 43.89 2.78ae 158.4ae �6.887ae

5-Thianonane C8H18S 12094 �39768j 125.79j 49.29 2.24ae 181.6ae �7.984ae

5-Thiadecane C9H20S 13684 �44699j 136.52j 54.69 1.70ae 204.8ae �9.081ae

6-Thiaundecane C10H22S 16094 �49630j 144.51j 60.09 1.16ae 228.0ae �10.178ae

Branched sulfides3-Methyl-2-thiabutane C4H10S 3093 �21556j 86.64j 28.71 4.99ag 89.8ag �3.434ag

3,3-Dimethyl-2-thiabutane C5H12S 4374 �29209j 89.28j 34.50 3.61ah 118.3ah �4.934ah

2-Methyl-3-thiapentane C5H12S 4292 �27094j 96.65j 34.11 4.45q 113.0q �4.531q

2,4-Dimethyl-3-thiapentane C6H14S 5313 �34142j 102.19j 40.53 3.77w 142.2w �6.339w

2,2-Dimethyl-3-thiapentane C6H14S 5576 �34747j 99.28j 39.90 3.14q 141.2q �6.007q

2,6-Dimethyl-4-thiaheptane C8H18S 10854 �42966j 119.22j 49.20 1.27ai 182.4ai �7.255ai

2,2,4,4-Tetramethyl-3-thiapentane

C8H18S 13498 �43826j 107.47j 51.30 1.50q 191.8q �8.309q

2,8-Dimethyl-5-thianonane C10H22S 14854 �52827j 137.94j 59.75 0.27aj 227.6aj �9.428aj

Cyclic sulfidesThiacyclopropane C2H4S 23187 19651ak 61.01al 12.85 �0.7am 53.0am �2.530am

Thiacyclobutane C3H6S 26043 14911an 68.14ao 16.55 �3.0am 75.3am �3.260am

Thiacyclopentane C4H8S 11408 �7716an 73.94ap 20.77 �6.1am 103.0am �4.320am

Thiacyclohexane C5H10S 12749 �15106an 77.26aq 25.78 �10.8am 140.0am �5.810am

Thiacycloheptane C6H12S 20161 �14660ar 86.50ar 29.24 �20.0am 189.5am �8.170am

2-Methylthiacyclopentane C5H10S 10836 �15194u 83.38as 27.19 �4.44q 121.2q �5.065q

3-Methylthiacyclopentane C5H10S 12045 �14230u 82.56as 27.19 �4.44q 121.2q �5.065q

Cyclopentyl-1-thiaethane C6H12S 16763 �15819u 94.01as 31.38 �5.78at 142.6at �6.025at

n-Alkyl disulfides2,3-Dithiabutane C2H6S2 2687 �6998j 79.28j 22.53 8.90au 51.5au �1.943au

2,3-Dithiapentane C3H8S2 3886 �12536j 89.29j 27.87 8.82av 71.8av �2.650av

3,4-Dithiahexane C4H10S2 5085 �18074j 99.30j 33.25 8.61av 93.1av �3.510av

3,4-Dithiaheptane C5H12S2 7085 �23004j 108.66j 38.57 8.26av 115.0av �4.470av

4,5-Dithiaoctane C6H14S2 9085 �27935j 118.02j 44.29 7.81au 138.7au �5.486au

4,5-Dithianonane C7H16S2 11084 �32866j 127.38j 49.69 7.27av 161.9av �6.583av

5,6-Dithiadecane C8H18S2 13085 �37796j 136.74j 55.09 6.73av 185.1av �7.680av

5,6-Dithiaundecane C9H20S2 15087 �42727j 146.09j 60.49 6.19av 208.3av �8.777av

6,7-Dithiadodecane C10H22S2 17087 �47658j 155.45j 65.89 5.65av 231.5av �9.874av

(Continued)

3836 L. Richard

Fig. 1. Vapor pressure curve for saturated liquid and gas carbondisulfide (O’Brien and Alford, 1951). The corresponding curve for H2Otaken from Haar et al. (1984) is shown for comparison. The symbolindicates the critical point for carbon disulfide.

Fig. 2. Standard molal heat capacity (CP° ) of carbon disulfide as a

function of temperature at 1 bar. The symbols correspond to experi-mental values reported by Brown and Manov (1937) for liquid CS2, andideal gas values reported by Waddington et al. (1962) for CS2 gas. Thestraight line for the liquid and the curve for the gas were calculatedfrom Eqn. 5 and 6 using values for the a, b, and c coefficients takenfrom Tables 4 and 5, respectively.


Compound Formula �G°fa,e �H°f

a S°b C°Pb,f ab bc 10�3 cd 105

ThiophenicsThiophene C4H4S 30017 27344an 66.65aw 17.50 �3.12ax 81.3ax �4.068ax

2-Methylthiophene C5H6S 29469 20047an 76.62ay 22.84 �1.48az 94.5az �4.338az

3-Methylthiophene C5H6S 29183 19812an 76.79ba 22.74 �1.86bb 96.1bb �4.558bb

2,5-Dimethylthiophene C6H8S 29362 12452bc 84.11bc 28.17 0.16bd 107.7bd �4.608bd

2-Isopropylthiophene C7H10S 32197 8587be 94.24be 33.47 �3.01be 140.7be �6.157be

a Cal mol�1 b Cal mol�1 K�1 c Cal mol�1 K�2 d Cal mol�1 K�3 e Calculated from Eqn. 13 f Calculated from Eqn. 6 g Calculated from the standardmolal enthalpy of formation for the liquid in Table 4 and the standard molal enthalpy of vaporization at 25°C and 1 bar given by Good et al. (1961)(see text) h Waddington et al. (1962) i Generated by regression of ideal gas heat capacity data reported by Waddington et al. (1962) j Calculated fromalgorithms given by Domalski and Hearing (1993) k Generated by regression of ideal gas heat capacity data reported by McCullough et al. (1954a)l Generated by regression of ideal gas heat capacity data reported by McCullough et al. (1958) m Generated by regression of ideal gas heat capacitydata reported by Scott et al. (1958) n Generated by regression of ideal gas heat capacity data reported by McCullough et al. (1953a) o Estimated usinggroup contributions taken from Helgeson et al. (1998) p Generated by regression of ideal gas heat capacity data reported by Scott et al. (1962a)q Estimated using group contributions generated in the present study (see text) or taken from Helgeson et al. (1998) r Calculated from the standardmolal enthalpy of formation for the liquid in Table 4 and the standard molal enthalpy of vaporization at 25°C and 1 bar given by Berg et al. (1961)s Berg et al. (1961) t Generated by regression of ideal gas heat capacity data reported by Berg et al. (1961) u Calculated from the standard molalenthalpy of formation for the liquid in Table 4 and the molal enthalpy of vaporization at 25°C given by Good (1972) v Scott and Crowder (1967)w Generated by regression of ideal gas heat capacity data reported by Scott and Crowder (1967) x Calculated from the standard molal enthalpy offormation for the liquid in Table 4 and the standard molal enthalpy of vaporization at 25°C and 1 bar given by Scott et al. (1956) y Scott et al. (1956)z Generated by regression of ideal gas heat capacity data reported by Scott et al. (1956) aa Calculated by adding to the properties and coefficients forbenzenethiol group contributions given by Helgeson et al. (1998) for the –CH2– group of ethylbenzene ab Generated by regression of ideal gas heatcapacity data reported by McCullough et al. (1957) ac Generated by regression of ideal gas heat capacity data reported by Scott et al. (1951)ad Generated by regression of ideal gas heat capacity data reported by Scott et al. (1957) ae Read off the straight line in Figure 19 (see text) af Generatedby regression of ideal gas heat capacity data reported by Scott et al. (1952a) ag Generated by regression of ideal gas heat capacity data reported byMcCullough and others (1955) ah Generated by regression of ideal gas heat capacity data reported by Scott and others (1962b) ai Calculated from theheat capacity power function coefficients of 3-thiapentane gas and those given by Helgeson et al. (1998) for the —CH3 and —CH (CH3)2 groups (seetext) aj Calculated from the heat capacity power function coefficients of 4-thiaheptane gas and those given by Helgeson et al. (1998) for the —CH3

and —CH(CH3)2 groups (see text) ak Calculated from the standard molal enthalpy of formation for the liquid in Table 4 and the standard molalenthalpy of vaporization at 25°C and 1 bar given by Guthrie et al. (1952) al Guthrie et al. (1952) am Read off the smooth curve in Figure 26an Calculated from the standard molal enthalpy of formation for the liquid in Table 4 and the standard molal enthalpy of vaporization at 25°C and1 bar recommended by Majer and Svoboda (1985) ao Scott et al. (1953) ap Hubbard et al. (1952) aq McCullough et al. (1954b) ar Stull et al. (1969)as Messerly et al. (1974) at Estimated by adding the value for the corresponding coefficient listed in Table 7 for the —S— (sat) group to that givenby Helgeson et al. (1998) for methylcyclopentane gas au Generated by regression of ideal gas heat capacity data reported by Hubbard et al. (1958b)av Read off the smooth curve in Figure 36 aw Hubbard et al. (1955) ax Generated by regression of ideal gas heat capacity data reported by Hubbardet al. (1955) ay Pennington et al. (1956) az Generated by regression of ideal gas heat capacity data reported by Pennington et al. (1956) ba McCulloughet al. (1953b) bb Generated by regression of ideal gas heat capacity data reported by McCullough et al. (1953b) bc TRC Thermodynamic Tables (1986)bd Estimated using Eqn. 46 be Estimated using Eqn. 47


eleven branched thiols are represented in Figure 3 together withthat for H2O. It can be seen in this figure that the curves for thebranched thiols with carbon number (n) equal to 3 and 4 fall inthe gas-phase region for H2O, while those with higher values ofn fall in the liquid-phase region for H2O. This distribution withn of the vapor pressure curves of the branched thiols on eachside of the vapor pressure curve for H2O is different than thatobserved by Helgeson et al. (1998) for both the n-1-alkanethi-ols and the branched alkanes. Values reported in the literaturefor the melting temperatures (Tm), boiling temperatures (Tv),molal enthalpy of melting (�Hm) at Tm, and molal enthalpy ofvaporization (�Hv) at Tv are listed in Table 2 and plotted assymbols as a function of carbon number in Figure 4. Smoothcurves have been drawn through the boiling points of branchedthiols with similar structures, thereby constituting homologousseries. One series contains 2-propanethiol (II), 2-methyl-1-propanethiol (IV), and 3-methyl-1-butanethiol (VIII). The otherseries corresponds to the 2-methyl-2-alkanethiols (V, VII, andXI). Insufficient information is available for drawing suchcurves for the enthalpies of vaporization or for the meltingproperties, which further depend on the odd or even values ofthe carbon number of the compounds (Helgeson et al., 1998).

The standard molal thermodynamic properties and heat ca-pacity power function coefficients of liquid and gas branchedthiols II-XII are listed in Tables 4 and 5. The standard molalenthalpies of formation (�Hf

°) and entropies (S°) at 25°C and 1bar for both the liquids and gases have been calculated usingthe group additivity algorithms of Domalski and Hearing(1993). This choice has been made to maintain consistencywith Helgeson et al. (1998), who also adopted these algorithmsfor n-alkanes, n-1-alkanethiols, and branched alkanes. It shouldbe noted that the group stoichiometry given by Domalski andHearing (1993) for calculating the �Hf

° and S° values of 2,3-dimethyl-2-butanethiol (XII) is erroneous, and should be thefollowing: (4 C–(H)3(C)) � (1 C–(H)(C)3) � (1 C–(C)3(S)) � (1 S–(C)(H)) � (4 –CH3 corr. (tert./quat.)).Adopting this group stoichiometry results in better agreement

with experimental values for both liquid and gas 2,3-dimethyl-2-butanethiol. Also in error is the symmetry number (�) usedby Domalski and Hearing (1993) to calculate the standardmolal entropy (S°) in the gas state for 2-methyl-2-butanethiol(VII). Adopting a value of � � 27 resulted in the value of S°listed in Table 5 and a better agreement with the correspondingliterature value given by Scott et al. (1962a). Symmetry num-bers for other branched thiol gases not given by Domalski andHearing (1993) and used in the present study are: � � 9 for2-methyl-1-butanethiol (VI) and 3-methyl-1-butanethiol (VIII),� � 27 for 3-methyl-2-butanethiol (IX), and 2-methyl-2-pen-tanethiol (XI), and � � 81 for 2,2-dimethyl-1-propanethiol (X)and 2,3-dimethyl-2-butanethiol (XII). The standard molal vol-umes (V°) at 25°C and 1 bar of branched thiol liquids (II-XII)in Table 4 have been calculated from the densities and molec-ular weights listed in Table 2. Values of the standard molalenthalpies of formation (�Hf

°) and entropies (S°) at 25°C and 1bar reported in the literature for branched thiol liquids andgases are represented as a function of carbon number in Figure5. Corresponding values calculated for the two homologousseries described above using the group additivity algorithms ofDomalski and Hearing (1993) are shown for comparison. Ingeneral, the calculated values of �Hf

° for branched thiols differfrom their experimental counterparts by less than 600 calmol�1 for the liquids, and by less than 800 cal mol�1 for thegases. The differences in S° values for both the liquids andgases are less than 1 cal mol�1K�1, except for 2-methyl-2-butanethiol (VII) liquid where the calculated value is 2.1 calmol�1K�1 bigger than its experimental counterpart. Alsoshown in Figure 5 are the standard molal volumes (V°) at 25°Cand 1 bar of branched thiol liquids calculated from the densitiesand molecular weights listed in Table 2. Linear regressions ofV° values for the branched thiols of the two homologous seriesresulted in the straight lines shown in Figure 5. The equationsof these lines are

V� � 47.23 � 15.55n (17)

for the homologous series II-IV-VIII, and

V� � 52.32 � 15.15n (18)

for the homologous series V-VII-XI. Differences between val-ues calculated with Eqn. 17 and 18 and their literature coun-terparts are less than 1 cm3mol�1.

The standard molal heat capacities (CP° ) of eight liquid and

gas branched thiols are represented as a function of temperaturein Figure 6. Regression of the experimental or ideal gas valuesrepresented by the symbols resulted in the a, b, and c coeffi-cients listed in Tables 4 and 5 for liquid and gas 2-propanethiol(II), 2-butanethiol (III), 2-methyl-1-propanethiol (IV), 2-meth-yl-2-propanethiol (V), and 2-methyl-2-butanethiol (VII), aswell as those listed in Table 4 for liquid 3-methyl-1-butanethiol(VIII) and 3-methyl-2-butanethiol (IX). The coefficients listedin Tables 4 and 5 for liquid and gas 2-methyl-1-butanethiol(VI) and in Table 5 for gas 3-methyl-1-butanethiol (VIII) wereestimated from group contributions taken from Helgeson et al.(1998) using the following group stoichiometry expressions:

�2-methyl-1-butanethiol � �–CH3 � �–CH2–,3-methylpentane � ��CHCH3

� �–CH2SH , (19)

Fig. 3. Vapor pressure curves for saturated liquid and gas branchedthiols II-XII. These curves have been calculated using the Antoineequation (Antoine, 1888) using coefficients given by Osborn and Dou-slin (1966). The corresponding curve for H2O (Haar et al., 1984) isshown for comparison.

3838 L. Richard

and

�3-methyl-1-butanethiol � �–CH(CH3)2 � �–CH2–,2-methylpentane � �–CH2SH

(20)

where � designates a temperature-independent heat capacity

power function coefficient. Comparisons with two experimen-tal values reported by Hossenlopp and Scott (1981) for thestandard molal heat capacity of 2-methyl-1-butanethiol (VI)gas indicate that the uncertainties associated with these predic-tions are of the order of 0.3 cal mol�1K�1. The uncertaintiesassociated with the predictions for 2-methyl-1-butanethiol (VI)

Fig. 4. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of branched thiols as a function of carbon number. The open and filled circles correspondto values reported in the literature (see footnote to Table 2 for references) for branched thiols with odd and even carbonnumbers, respectively. The smooth curves were drawn to highlight the carbon number dependence of these properties withinhomologous series (see text).


liquid should be of the order of 1 to 1.2 cal mol�1K�1, assuggested by a comparison between experimental and predictedvalues for the heat capacity of liquid 3-methyl-1-butanethiol(VIII). In order to predict the standard molal heat capacity of3-methyl-2-butanethiol (IX) gas as a function of temperature,values of the a, b, and c coefficients for a –CH(SH)CH3 groupwere first retrieved from those of 2-butanethiol gas listed inTable 5 using the group stoichiometry expression shown inTable 6 and values of a, b, and c for the –CH3 and –CH2–groups taken from Helgeson et al. (1998). The coefficients ofthe –CH(SH)CH3 group in the gas state have been listed inTable 7 and combined with those of a –CH(CH3)2 group givenby Helgeson et al. (1998) in the group stoichiometry expression

�3-methyl-2-butanethiol � �–CH(CH3)2 � �–CH(SH)CH3 (21)

to generate the a, b, and c coefficients of 3-methyl-2-butane-

thiol (IX) gas in Table 5 and the dashed curve shown in Figure6.

The heat capacity power function coefficients listed in Ta-bles 4 and 5 for the three remaining branched thiols X-XII werecalculated as follows. Liquid and gas heat capacity valuesrecommended by Zabransky et al. (1996) and Stull et al. (1969)for 2,2-dimethylbutane were regressed with Eqn. 5 and 6,which resulted in a � 4.83 cal mol�1K�1, b � 0.1220 calmol�1K�2 and c � 357300 cal K mol�1 for the liquid, and a ��2.17 cal mol�1K�1, b � 0.1380 cal mol�1K�2 and c ��5.765�10�5 cal mol�1K�3 for the gas. Combining thesevalues with those given by Helgeson et al. (1998) for the –CH3

group and the –CH2– group of n-hexane resulted in the a, b,and c coefficients shown in Table 7 for a –C(CH3)3 group in theliquid and gas states. These coefficients were used togetherwith those of the –CH2SH group to calculate the values of a, b,

Fig. 5. Standard molal enthalpies of formation (�Hf°), entropies (S°), and volumes (V°) at 25°C and 1 bar as a function

of carbon number for branched thiol liquids and gases. The symbols for �Hf° and S° correspond to literature values reported

by McCullough et al. (1953a, 1954a, 1958), Hubbard and Waddington (1954), Hubbard et al. (1954, 1958a), Scott et al.(1958, 1962a), Good (1972), and Messerly et al. (1974). The lines correspond to �Hf

° and S° values calculated for thehomologous series II-IV-VIII and V-VII-XI (see text) using group additivity algorithms given by Domalski and Hearing(1993). The symbols for V° correspond to values calculated from the densities and molecular weights listed in Table 2.Linear regressions of V° values of compounds of the two homologous series resulted in the lines shown in the figure.

3840 L. Richard

and c listed in Tables 4 and 5 for liquid and gas 2,2-dimethyl-1-propanethiol (X) according to

�2,2-dimethyl-1-propanethiol � �–C(CH3)3 � �–CH2SH . (22)

Due to insufficient literature data on the heat capacities of2-methyl-2-alkanethiols, the heat capacity power function co-efficients listed in Tables 4 and 5 for liquid and gas 2-methyl-2-pentanethiol (XI) were estimated by adding the values of a,b, and c given by Helgeson et al. (1998) for the –CH2– groupin n-heptane to the corresponding values listed in Tables 4 and5 for 2-methyl-2-butanethiol (VII). The a, b, and c coefficientsof 2-methyl-2-butanethiol were further combined with thosegiven by Helgeson et al. (1998) for the –CH3 group and the–CH2– group of n-hexane to retrieve the coefficients listed inTable 7 for a –C(SH)(CH3)2 group according to the groupstoichiometry shown in Table 6. The a, b, and c coefficients forthe –C(SH)(CH3)2 group were finally combined with thosegiven by Helgeson et al. (1998) for the –CH(CH3)2 group in thegroup stoichiometry expression

�2,3-dimethyl-2-butanethiol � �–CH(CH3)2 � �–CH(SH)(CH3)2 , (23)

which resulted in the values of the a, b, and c coefficients listedin Tables 4 and 5 for liquid and gas 2,3-dimethyl-2-butanethiol(XII).

It should be noted that standard molal heat capacities ofbranched thiols in the ideal gas state have been previouslycalculated by Alberty et al. (1987) using the Benson (1976)group method. A comparison between these values and thoseestimated in the present study indicates differences which areless than 0.6 cal mol�1K�1 at 298.15 K, and less than 2 calmol�1K�1 at 800 K.

4.3. Cyclic Thiols

Thermodynamic studies of cyclopentanethiol (XIII) and cy-clohexanethiol (XIV) have been reported by Berg et al. (1961),Osborn and Douslin (1966), Messerly et al. (1967), Scott andCrowder (1967), and Good (1972). The vapor pressure curvesfor saturated liquid and gas cyclopentanethiol and cyclohex-anethiol are depicted in Figure 7, together with the correspond-ing curve for H2O. Unlike their cycloalkane counterparts whichplot on each side of the curve for H2O (Helgeson et al., 1998),

Fig. 6. Standard molal heat capacities (CP° ) of branched thiols as a function of temperature at 1 bar. The symbols represent

experimental or ideal gas values reported by McCullough et al. (1953a, 1954a, 1958), Scott et al. (1958, 1962a), andMesserly et al. (1974). The solid curves were calculated using Eqn. 5 and 6 together with values of a, b, and c taken fromTables 4 and 5. The dashed curves were calculated using group contributions taken from Helgeson et al. (1998) or generatedin the present study (see text).


the vapor pressure curves for both cyclic thiols fall in thegas-phase region of the system H2O.

Values of the standard molal heat capacity (CP° ) as a function

of temperature at 1 bar reported in the literature for liquid andgas cycloalkanethiols have been represented as symbols inFigure 8. Regression of these values with Eqn. 5 and 6 resultedin the a, b, and c coefficients listed in Tables 4 and 5 forcyclopentanethiol and cyclohexanethiol, and the curves shownin Figure 8. Also listed in Tables 4 and 5 are values of thestandard molal enthalpies of formation (�Hf

°) at 25°C and 1 barrecalculated in the manner described above from the originalcombustion data and the standard molal enthalpy of vaporiza-

tion (�Hv°) at 25°C and 1 bar. The standard molal entropies

(S°) in Tables 4 and 5 were taken from the literature, andused together with values for the entropies of the elementstaken from Cox et al. (1989) to calculate the standard molalGibbs free energies of formation (�Gf

°) of the liquid and gascyclic thiols from Eqn. 13. The standard molal volumes (V°)at 25°C and 1 bar listed in Table 4 for cyclopentanethiol andcyclohexanethiol liquids were calculated from the densitiesand molecular weights listed for these species in Table 2.

The standard molal thermodynamic properties and heat ca-pacity power function coefficients of the liquid cycloalkanethi-ols listed in Table 4 were combined together with those of the

Table 6. Group stoichiometries of the reference compounds adopted in the present study.

3842 L. Richard

Table 7. Group contributions retrieved or used in the present study to calculate the standard molal thermodynamic properties at 25°C and 1 bar andthe heat capacity power function coefficients of crystalline, liquid, and gas organic sulfur compounds.

(Continued)



(Continued)

3844 L. Richard

liquid (5)�CH2 and (6)�CH2 cyclic groups given by Richardand Helgeson (1998) to obtain the corresponding properties andcoefficients of two liquid (5)�CHSH and (6)�CHSH cyclicthiol groups in Table 7 using the group stoichiometry expres-sions shown in Table 6. The same procedure was applied for(5)�CHSH and (6)�CHSH groups in the ideal gas state, butthe properties and coefficients of the gas (5)�CH2 and

(6)�CH2 groups had first to be obtained from those given byHelgeson et al. (1998) for cyclopentane and cyclohexane gasesusing the group stoichiometry expressions shown in Table 6.The properties and coefficients of the (5)�CH2, (6)�CH2,(5)�CHSH and (6)�CHSH groups have been listed in Table 7.


Fig. 7. Vapor pressure curves for saturated liquid and gas cyclopen-tanethiol (C5H10S) and cyclohexanethiol (C6H12S). The data for draw-ing these curves were taken from Osborn and Douslin (1966). Thecorresponding curve for H2O (Haar et al., 1984) is shown for compar-ison.

Fig. 8. Standard molal heat capacity (CP° ) of cyclic thiols as a

function of temperature at 1 bar. The symbols correspond to experi-mental or ideal gas values reported by Berg et al. (1961) for cyclopen-tanethiol, Messerly et al. (1967) for liquid cyclohexanethiol, and Scottand Crowder (1967) for cyclohexanethiol gas. The curves were calcu-lated from Eqn. 5 and 6 using values for the a, b, and c coefficientstaken from Tables 4 and 5, respectively.


4.4. Aromatic Thiols

Both vapor pressure curves for saturated liquid and gasbenzenethiol (XV) and phenylmethanethiol (XVI) depicted inFigure 9 fall in the gas-phase region of the system H2O, as dothe n-alkylbenzenes with n � 7 (Helgeson et al., 1998). Thestandard molal thermodynamic properties and heat capacitypower function coefficients of crystalline, liquid and gas ben-zenethiol (XV) are listed in Tables 3, 4, and 5. The values of thea, b, and c coefficients given in these tables were obtained byregressing with Eqn. 5 and 6 experimental or ideal gas heatcapacities reported in the literature and represented as symbolsin Figures 10 and 11. It can be seen in these figures that theregression curves closely represent all of the experimentalvalues. Note that for crystalline benzenethiol, only the heat

capacity data reported above the �-type transition4 ( 128 K)observed by Scott et al. (1956) have been included in theregression. The standard molal enthalpies of formation (�Hf

°) at25°C and 1 bar of benzenethiol and phenylmethanethiol liquidsin Table 4 were recalculated from the original combustion datareported by Scott et al. (1956) and Good (1972) in the mannerdescribed above, and combined with the standard molal enthal-pies of vaporization (�Hv

°) at 25°C and 1 bar given by the sameauthors to obtain the values of �Hf

° listed in Table 5 for the twoaromatic thiol gases. The standard molal entropies (S°) at 25°Cand 1 bar of benzenethiol liquid and gas in Tables 4 and 5 weretaken from Scott et al. (1956), and the standard molal volume(V°) at 25°C and 1 bar of benzenethiol liquid in Table 4 wascalculated from the density and molecular weight given inTable 2. The values of S°, V°, and the a, b, and c coefficientsof phenylmethanethiol liquid and gas were estimated by addingto the corresponding properties and coefficients of benzenethiolthe group contributions given by Helgeson et al. (1998) for the–CH2–group in ethylbenzene.

The standard molal volume (V°) at 25°C and 1 bar ofbenzenethiol crystal in Table 3 has been estimated using thevolume increment algorithm of Immirzi and Perini (1977), butthe standard molal enthalpy of formation (�Hf

°) and entropy(S°) were retrieved in the following manner. First, the apparentstandard molal enthalpy of formation (�H°) and entropy (S°) ofbenzenethiol liquid at the melting temperature (Tm) were cal-culated from

�H� (liquid) � �Hf� � a �T � Tr� �

b

2�T2 � Tr

2�

� c�1

T�

1

Tr� � �Pr

P

V� dP � �T�Pr

P��V�

�T �P

dP�T

(24)

4 A �-type transition is characterized by the absence of a discontinuityin the temperature dependence of a given thermodynamic property suchas the standard molal heat capacity (Helgeson et al., 1978).

Fig. 9. Vapor pressure curves for saturated liquid and gas benzene-thiol (C6H6S) and phenylmethanethiol (C7H8S). The data for drawingthese curves were taken from Osborn and Douslin (1966) and Osbornand Scott (1980). The corresponding curve for H2O (Haar et al., 1984)is shown for comparison.

Fig. 10. Standard molal heat capacity (CP° ) of liquid and gas ben-

zenethiol as a function of temperature at 1 bar. The symbols correspondto experimental or ideal gas values reported by Scott et al. (1956). Thecurves were calculated from Eqn. 5 and 6 using values for the a, b, andc coefficients taken from Tables 4 and 5, respectively.

Fig. 11. Standard molal heat capacity (CP° ) of crystalline benzene-

thiol as a function of temperature at 1 bar. The symbols correspond toexperimental data reported by Scott and others (1956). The curve wasgenerated from Eqn. 5 using values for the a, b, and c coefficients takenfrom Table 3.

3846 L. Richard

and

S� (liquid) � SPr,Tr

� � a ln� T

Tr� � b �T � Tr� �c

2 � 1

T2 �1

Tr2�

� ��Pr

P��V�

�T �P

dP�T

. (25)

The corresponding apparent standard molal properties for thecrystal at Tm were then retrieved from those for the liquidaccording to

�H� (crystal) � �H� (liquid) � �Hm , (26)

S� (crystal) � S� (liquid) � �Sm , (27)

and

�Sm ��Hm

Tm(28)

using the values listed in Table 2 for the melting temperature(Tm) and molal enthalpy of melting (�Hm) of benzenethiol.Finally, the standard molal enthalpy of formation (�Hf

°) andentropy (S°) of crystalline benzenethiol at 25°C and 1 bar werecalculated from

�Hf� � �H� (crystal) � a �T � Tr� �

b

2�T2 � Tr

2�

� c�1

T�

1

Tr� � �Pr

P

V� dP � �T�Pr

P��V�

�T �P

dP�T

(29)

and

SPr,Tr

� � S� (crystal) � a ln� T

Tr� � b �T � Tr� �c

2 � 1

T2 �1

Tr2�

� ��Pr

P��V�

�T �P

dP�T

. (30)

The standard molal thermodynamic properties and heat capac-ity power function coefficients of crystalline, liquid, and gasbenzenethiol in Tables 3–5 have been used to retrieve thecorresponding properties and coefficients listed in Table 7 foran aromatic thiol (6)�C-SH group from the group stoichiom-etry expression shown in Table 6 and group contributions eithertaken from Richard and Helgeson (1998) for the (6)�CH groupin the crystalline and liquid states, or retrieved from the prop-erties and coefficients given by Helgeson et al. (1998) forbenzene gas with the group stoichiometry shown in Table 6.The properties and coefficients for the gas (6)�CH group havealso been listed in Table 7.

4.5. n-Alkyl Sulfides

Calorimetric studies of n-alkyl sulfides (or n-thiaalkanes)have been reported by Osborne et al. (1942), Scott et al. (1951,1952a, 1957), Hubbard and Waddington (1954), Hubbard et al.(1954, 1958a), McCullough et al. (1961) and Mackle andMayrick (1962). The compounds investigated include 2-thia-propane (XVII), 2-thiabutane (XVIII), 2-thiapentane (XIX),3-thiapentane (XX), 2-thiahexane (XXI), 3-thiahexane (XXII),2-thiaheptane (XXIII), 4-thiaheptane (XXIV), 5-thianonane(XXV), and 6-thiaundecane (XXVI). From the idealized struc-tures shown in the Appendix, it can be seen that the n-alkylsulfides considered in the present study belong to two differenthomologous series. In one of these series, the sulfur atomalways appears in position 2 next to a terminal methyl group,which corresponds to the general structure

Fig. 12. Vapor pressure curves for saturated liquid and gas n-alkyl sulfides (White et al., 1952; Osborn and Douslin,1966): [a] 2-thiapropane (C2H6S), 2-thiabutane (C3H8S), 2-thiapentane (C4H10S), and 2-thiahexane (C5H12S); [b] 3-thia-pentane (C4H10S), 3-thiahexane (C5H12S), 4-thiaheptane (C6H14S), and 5-thianonane (C8H18S). The corresponding curvefor H2O (Haar et al., 1984) is shown for comparison.


CH3–(CH2)m–S–CH3.

In the other series, methylene groups are added alternativelyon each side of the sulfur atom which moves progressivelytowards the center of the molecule, corresponding to the gen-eral structure

CH3–(CH2)m–S–(CH2)m’–CH3.

The vapor pressure curves for saturated liquid and gas n-alkyl sulfides are depicted in Figure 12 together with that forH2O. It can be seen that the curves for 2- and 3-thiapentane(C4H10S) are nearly coincident with that for water on the

Fig. 13. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of n-alkyl sulfides as a function of carbon number. The open and filled circles correspondto values reported in the literature (see footnote to Table 2 for references) for n-alkyl sulfides with odd and even carbonnumbers, respectively. The smooth curves were drawn to highlight the carbon number dependence of these properties withinhomologous series (see text). The abbreviations on the symbols refer to 2-thiapropane (2tpro), 2-thiabutane (2tbut),2-thiapentane (2tpen), 2-thiahexane (2thex), 2-thiaheptane(2thep), 2-thiaoctane (2toct), 2-thianonane (2tnon), 2-thiadecane(2tdec), 2-thiaundecane (2tund), 3-thiapentane (3tpen), 3-thiahexane (3thex), 4-thiaheptane (4thep), 4-thiaoctane (4toct),5-thianonane (5tnon), and 6-thiaundecane (6tund), respectively.

3848 L. Richard

temperature range investigated, which is different from whatHelgeson et al. (1998) observed for both the n-alkanes and then-1-alkanethiols. The curve for n-hexane (C6H14) is superim-posed on the curve for H2O in the case of the n-alkanes, whilethat for n-1-butanethiol (C4H10S) is crossing that for H2Oslightly above 100°C. Values reported in the literature for themelting and boiling temperatures (Tm and Tv, respectively) andthe molal enthalpies of melting and vaporization at Tm and Tv

(�Hm and �Hv, respectively) of n-alkyl sulfides have beenlisted in Table 2 and plotted as a function of carbon number inFigure 13. It can be seen in this figure that the melting pointsof n-alkyl sulfides fall on separate curves both for compoundswith odd or even carbon numbers, and for compounds belong-ing to a particular homologous series for which a distinctionhas been made above. In contrast, the boiling points and en-thalpies of vaporization are insensitive to whether the numberof carbon atoms in the compound is odd or even, but the boiling

properties still plot on two distinct curves for compoundsbelonging to one homologous series or the other.

The standard molal enthalpies of formation (�Hf°) and en-

tropies (S°) at 25°C and 1 bar listed in Tables 4 and 5 for liquidand gas n-alkyl sulfides have been calculated using the groupadditivity algorithms of Domalski and Hearing (1993) and arecompared to experimental values reported in the literature inFigure 14. Except for 6-thiaundecane (XXVI) liquid, the dif-ferences between the calculated values of �Hf

° for both liquidand gas n-alkyl sulfides and their literature counterparts are lessthan or equal to the reported experimental uncertainties. Thisobservation is also true for the S° values of the n-alkyl sulfidegases, except 3-thiapentane (XX) for which the difference is0.4 cal mol�1K�1. The calculated values for the standard molalentropies (S°) of liquid n-alkyl sulfides differ from their exper-imental counterparts by 0.3 to 1.3 cal mol�1K�1, and by 2.2 calmol�1K�1 for 3-thiapentane (XX). The standard molal vol-


of carbon number for n-alkyl sulfide liquids and gases. The symbols for �Hf° and S° correspond to literature values reported

by Scott et al. (1951, 1952a, 1957), Hubbard and Waddington (1954), Hubbard et al. (1954, 1958a), McCullough et al.(1957, 1961), and Mackle and Mayrick (1962). The lines correspond to �Hf

° and S° values calculated for the two differenthomologous series considered in the present study (see text) using group additivity algorithms given by Domalski andHearing (1993). The symbols for V° correspond to values calculated from the densities and molecular weights listed in Table2. Linear regressions of V° values for compounds of the two homologous series resulted in the lines shown in the figure.


umes (V°) at 25°C and 1 bar of liquid n-alkyl sulfides calculatedfrom the densities and molecular weights listed in Table 2 havealso been plotted as symbols in Figure 14. Regression of theseV° values for both homologous series resulted in the straightlines shown in the figure. The equations of these lines are

V� � 40.88 � 16.66n (31)

for the series in which the sulfur atom appears in position 2, and

V� � 40.37 � 16.91n (32)

for the other series. Eqn. 31 and 32 were used to calculate theV° values of the liquid n-alkyl sulfides listed in Table 4.

The standard molal heat capacities (CP° ) of liquid n-alkyl

sulfides have been represented as a function of temperature at1 bar in Figure 15, and as a function of carbon number atvarious temperatures at 1 bar in Figure 16. The symbols inthese figures correspond to experimental data reported in theliterature, but the solid curves have been calculated from Eqn.5 using values of the a, b, and c coefficients listed in Table 4.It can be seen in Table 4 that for a given carbon number, thesame values of a, b, and c are used to describe the temperaturedependence of the standard molal heat capacity of liquid n-alkyl sulfides from both of the homologous series mentionedabove. The strategy used to retrieve these coefficients was thefollowing. Experimental CP

° values reported above 250 K for5-thianonane (C8H18S) were first regressed with Eqn. 5, whichresulted in the values of a, b, and c listed for this compound inTable 4 and the symbols shown in Figure 17. For n-alkyl sulfideliquids with n � 8, group values taken from Helgeson et al.(1998) for the –CH2– increments in n-alkane liquids weresuccessively added to the a, b, and c values of 5-thianonaneaccording to

�CnH2(n�1)S � �C8H18S � �–CH2–,Cn�1H2(n�2). (33)

This resulted in the values given in Table 4 for liquid 5-thia-decane and 6-thiaundecane, and the solid curves in Figure 17.These curves were extrapolated below n � 8 by fitting theexperimental CP

° values in Figure 15 for liquid n-alkyl sulfideswith n � 8 with the constraint that the isotherms shown inFigure 16 intersect at a common fictive carbon number n* ��2.7 for which CP

° � a � b � c � 0 at all temperatures. Thisconstraint resulted in the smooth dashed curves shown inFigure 17 for the carbon number dependence of the heat ca-pacity power function coefficients and the values of a, b, and clisted in Table 4 for n-alkyl sulfide liquids.

Ideal gas heat capacity values as a function of temperature at1 bar reported in the literature for 2-thiapropane, 2-thiabutane,2-thiapentane, and 3-thiapentane have been plotted as symbolsin Figure 18. Regression of these values with Eqn. 6 resulted inthe values of a, b, and c listed for these four compounds inTable 5, and plotted as a function of carbon number in Figure19. Smooth curves have been drawn through the symbolscorresponding to the regression values, and extended up to n �5. Above this carbon number, the dashed lines correspond tothe values listed in Table 5 for n-alkyl sulfide gases with n �5. These values have been calculated using group contributionsfor –CH2– aliphatic groups in the gas state given by Helgesonet al. (1998) as a–CH2–

� �0.539 cal mol�1K�1, b–CH2–�

0.0232 cal mol�1K�2, and c–CH2–� �1.097 � 10�5 cal mol�1

K�3.The standard molal thermodynamic properties and heat ca-

pacity power function coefficients of liquid and gas 2-thiapro-pane in Tables 4 and 5 have been combined with those for the–CH3 methyl group in Table 7 and the group stoichiometry

Fig. 15. Standard molal heat capacities (CP° ) of liquid n-alkyl sulfides

as a function of temperature at 1 bar. The symbols correspond toexperimental data reported in the literature. The curve for C8H18S wasgenerated by regression of the experimental data represented by thesymbols with Eqn. 5. The curves for the other n-alkyl sulfides werepredicted independently using the strategy described in the text, andwere calculated from Eqn. 5 using values of the a, b, and c coefficientstaken from Table 4.

Fig. 16. Standard molal heat capacities (CP° ) of liquid n-alkyl sulfides

as a function of carbon number (n) at various temperatures at 1 bar. Thesymbols correspond to experimental data reported in the literature, butthe curves were generated from Eqn. 5 using values of a, b, and c listedin Table 4 for values of n � 2. Below n � 2, the curves wereextrapolated to intersect at a common fictive carbon number n* (seetext).

3850 L. Richard

expression shown in Table 6 to retrieve the properties andcoefficients which have been listed in Table 7 for a saturatedsulfide –S–(sat) group in the liquid and gas states. It should benoted that no distinction is made here between the properties ofa methyl group in an n-alkane and those of a methyl groupneighboring a sulfur atom in an organic sulfur compound. Asimilar assumption has been made by Domalski and Hearing(1993) in their group additivity algorithms for calculating thestandard molal enthalpies of formation (�Hf

°), entropies (S°),and heat capacities (CP

° ) of organic sulfur compounds at 25°Cand 1 bar.

4.6. Branched Sulfides

Investigations of the thermodynamic properties of eightbranched sulfides in the liquid and gas states have been re-ported by McCullough et al. (1955), Mackle and Mayrick(1962), Scott et al. (1962b), Messerly et al. (1967), Scott andCrowder (1967), and Good (1972). The compounds investi-gated include 3-methyl-2-thiabutane (XXVII), 3,3-dimethyl-2-thiabutane (XXVIII), 2-methyl-3-thiapentane (XXIX), 2,4-di-methyl-3-thiapentane (XXX), 2,2-dimethyl-3-thiapentane(XXXI), 2,6-dimethyl-4-thiaheptane (XXXII), 2,2,4,4-tetra-methyl-3-thiapentane (XXXIII), and 2,8-dimethyl-5-thianonane (XXXIV).

The vapor pressure curves for five of these eight branchedsulfides (compounds XXVII-XXX and XXXIII) are shown inFigure 20, together with that for saturated liquid and gas H2O.It can be seen in this figure that 3-methyl-2-thiabutane(C4H10S; XXVII) plots in the liquid-phase region of the systemH2O, while the other branched sulfides with n � 4 plot in thegas-phase region of that system. This observation is consistentwith that made above for the vapor pressure curves of branchedthiols. The temperatures of melting and boling (Tm and Tv,respectively) and the molal enthalpies of melting and vapor-ization (�Hm and �Hv, respectively) of the eight branchedsulfides have been listed in Table 2 and plotted as a function ofcarbon number in Figure 21. A smooth curve was drawnthrough the boiling points of 2,4-dimethyl-3-thiapentane(XXX), 2,6-dimethyl-4-thiaheptane (XXXII), and 2,8-dimeth-yl-5-thianonane (XXXIV) which belong to the same homolo-gous series.

The standard molal enthalpies of formation (�Hf°) and stan-

dard molal entropies (S°) at 25°C and 1 bar listed in Tables 4and 5 for the eight branched sulfides in the liquid and gas stateshave been calculated using the group contribution algorithms ofDomalski and Hearing (1993). Differences between the calcu-lated �Hf

° values of liquid and gas branched sulfides and theirexperimental counterparts range between 0.03 and 1.5 kcalmol�1, the latter value being 1 kcal mol�1 larger than the

Fig. 17. Coefficients for Eqn. 5 for n-alkyl sulfide liquids as a function of carbon number at 1 bar. The symbols correspondto values of a, b, and c obtained by regression of experimental data reported for 5-thianonane liquid. The solid curvescorrespond to values of a, b, and c calculated by adding –CH2– n-alkane increments to the values for 5-thianonane. Thedashed curves were adjusted by fitting experimental heat capacity values for n-alkyl sulfide liquids with n � 8 and theconstraint that a � b � c � CP

° � 0 at n* � �2.7 (see text).

Fig. 18. Standard molal heat capacities (CP° ) of gas n-alkyl sulfides as

a function of temperature at 1 bar. The symbols correspond to ideal gasheat capacities reported in the literature for 2-thiapropane (filled cir-cles), 2-thiabutane (open circles), 2-thiapentane (open triangles), and3-thiapentane (filled triangles). The curves were calculated using Eqn.6 together with values of a, b, and c listed in Table 5.


maximum experimental uncertainty reported by Mackle andMayrick (1962). The difference between the S° value calculatedfor 3-methyl-2-thiabutane gas and its calorimetric counterpartis 0.8 cal mol�1K�1, which is greater than the uncertaintyreported by McCullough et al. (1955) by 0.6 cal mol�1K�1. Aconsiderable discrepancy, the origin of which is unclear, isobserved between the experimental and calculated values of S°for both liquid and gas 2,4-dimethyl-3-thiapentane. The differ-ences are as high as 2.9 cal mol�1K�1 for the gas and 4.0 calmol�1K�1 for the liquid. The standard molal volumes (V°) at298.15 K and 1 bar of the liquid branched sulfides listed inTable 4 were calculated from the densities and molecularweights given in Table 2.

Values of the standard molal heat capacity (CP° ) as a function

of temperature at 1 bar reported in the literature for liquid and

gas 3-methyl-2-thiabutane (XXVII), 3,3-dimethyl-2-thiabutane(XXVIII), and 2,4-dimethyl-3-thiapentane (XXX) have beenrepresented as symbols in Figure 22. Regression of these valueswith Eqn. 5 and 6 resulted in the values of a, b, and c listed inTables 4 and 5 for these compounds, and the regression curvesshown in Figure 22.

The standard molal thermodynamic properties and heat ca-pacity power function coefficients listed in Table 7 for anisopropyl group and a tert-butyl group neighboring a sulfuratom ((S)—CH(CH3)2 and (S)—C(CH3)3, respectively) havebeen retrieved from the corresponding properties and coeffi-cients for liquid and gas 3-methyl-2-thiabutane (XXVII) and3,3-dimethyl-2-thiabutane (XXVIII) using the group stoichi-ometry expressions shown in Table 6. The a, b, and c coeffi-cients for these two groups were used to estimate those listed inTables 4 and 5 for liquid and gas 2-methyl-3-thiapentane(XXIX), 2,2-dimethyl-3-thiapentane (XXXI), and 2,2,4,4-tetra-methyl-3-thiapentane (XXXIII) according to

�2-methyl-3-thiapentane � �(S)–CH(CH3)2 � �–S–(sat)

� �–CH2–,2-methylpentane � �–CH3 , (34)

�2,2-dimethyl-3-thiapentane � �(S)–C(CH3)3 � �–S–(sat)

� �–CH2–,n-heptane � �–CH3 , (35)

and

�2,2,4,4-tetramethyl-3-thiapentane � 2�(S)–C(CH3)3 � �–S–(sat) , (36)

where � stands for the a, b, or c coefficient of the subscriptedspecies or group. From a comparison between independentestimates of the heat capacity of 2,4-dimethyl-3-thiapentaneand values reported in the literature for this compound, theuncertainties associated with the predictions made above areexpected to be of the order of 0.6 - 1.2 cal mol�1K�1 for theliquids, and 0.2 - 1.0 cal mol�1K�1 for the gases. Finally,the heat capacity power function coefficients listed in Tables 4and 5 for liquid and gas 2,6-dimethyl-4-thiaheptane (XXXII)

Fig. 19. Coefficients for Eqn. 6 for n-alkyl sulfide gases as a function of carbon number at 1 bar. The symbols correspondto values of a, b, and c obtained by regression of ideal gas heat capacity data reported in the literature. Smooth curves havebeen drawn through the symbols and extrapolated up to n � 5. The dashed lines correspond to values of a, b, and ccalculated for n-alkyl sulfides with n � 5 using –CH2– increments taken from Helgeson et al. (1998)—see text.

Fig. 20. Vapor pressure curves for saturated liquid and gas 3-methyl-2-thiabutane (XXVII), 3,3-dimethyl-2-thiabutane (XXVIII), 2-methyl-3-thiapentane (XXIX), 2,4-dimethyl-3-thiapentane (XXX), and 2,2,4,4-tetramethyl-3-thiapentane (XXXIII). The data for drawing these curveswere taken from White et al. (1952), Osborn and Douslin (1966), andOsborn and Scott (1980). The corresponding curve for H2O (Haar et al.,1984) is shown for comparison.

3852 L. Richard

and 2,8-dimethyl-5-thianonane (XXXIV) were calculatedfrom those of 3-thiapentane (XX) and 4-thiaheptane (XXIV)and group contributions taken from Helgeson et al. (1998)according to:

�2,6-dimethyl-4-thiaheptane � �3-thiapentane � 2�–CH3 � 2�–CH(CH3)2

(37)

and

�2,8-dimethyl-5-thianonane � �4-thiaheptane � 2�–CH3 � 2�–CH(CH3)2 .

(38)

4.7. Cyclic Sulfides

Thermodynamic studies have been reported in the literaturefor a number of cyclic sulfides, including thiacyclopropane(XXXV), thiacyclobutane (XXXVI), thiacyclopentane (XXX-

Fig. 21. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of branched sulfides as a function of carbon number. The open and filled circlescorrespond to values reported in the literature (see footnote to Table 2 for references) for branched sulfides with odd andeven carbon numbers, respectively. The smooth curve was drawn to highlight the carbon number dependence of the boilingtemperature within the homologous series constituted by 2,4-dimethyl-3-thiapentane (XXX), 2,6-dimethyl-4-thiaheptane(XXXII), and 2,8-dimethyl-5-thianonane (XXXIV).


VII), thiacyclohexane (XXXVIII), thiacycloheptane (XXXIX),2-methylthiacyclopentane (XL), 3-methylthiacyclopentane(XLI), and cyclopentyl-1-thiaethane (XLII).5

The liquid-vapor saturation curves for seven of these eightcyclic sulfides are depicted in Figure 23, together with that forH2O. It can be seen in this figure that thiacyclopropane lies inthe liquid-phase region of the system H2O, which is also thecase of thiacyclobutane at temperatures below 120°C. Allthe other cyclic sulfides lie in the gas-phase region of thesystem H2O. The temperatures of melting and boling (Tm andTv, respectively) and the molal enthalpies of melting and va-

porization (�Hm and �Hv, respectively) listed in Table 2 for thefive unsubstituted cyclic sulfides (XXXV-XXXIX) have beenplotted as a function of carbon number in Figure 24. It can beseen in this figure that the boiling properties of the cyclicsulfides describe smooth functions of carbon number (n) whichare independent of the odd or even values of n for the com-pounds. By contrast, their melting properties fall on distinctlines (or curves when more than two data are available) forcyclic sulfides with odd or even values of n.

The standard molal thermodynamic properties and heat ca-pacity power function coefficients of the eight cyclic sulfides(XXXV-XLII) in the liquid and gas states have been listed inTables 4 and 5. The standard molal enthalpies of formation(�Hf

°) at 25°C and 1 bar of the liquid cyclic sulfides wererecalculated from the original combustion studies in the mannerdescribed above, and combined with values reported in theliterature for the standard molal enthalpies of vaporization(�Hv

°) at 25°C and 1 bar to obtain the values of �Hf° listed in

Table 5 for the gases. The values listed in Tables 4 and 5 for thestandard molal entropy (S°) at 25°C and 1 bar of the liquid andgas cyclic sulfides were taken from the literature. Except forthiacycloheptane (XXXIX), the standard molal volumes (V°) at25°C and 1 bar of the liquid cyclic sulfides in Table 4 werecalculated from the densities and molecular weights listed inTable 2. A linear regression of the V° values for thiacyclopro-pane, thiacyclobutane, thiacyclopentane, and thiacyclohexaneresulted in

V� � 29.24 � 14.91n, (39)

which was used to calculate the V° value listed in Table 4 forthiacycloheptane liquid.

Values reported in the literature for the standard molal heatcapacity (CP

° ) of liquid and gas cyclic sulfides as a function oftemperature at 1 bar have been represented as symbols inFigure 25. Regression of the data for the unsubstituted cyclicsulfides (XXXV-XXXIX) with Eqn. 5 and 6 resulted in valuesof a, b, and c which have been plotted as a function of carbonnumber in Figure 26. Two straight lines and a smooth curve

5 Sunner (1949, 1963), Guthrie et al. (1952), Hubbard et al. (1952),Scott et al. (1953), McCullough et al. (1954b), Davies and Sunner(1962), Messerly et al. (1974).

Fig. 22. Standard molal heat capacity (CP° ) of liquid and gas branched

sulfides as a function of temperature at 1 bar. The symbols correspondto experimental or ideal gas values reported by McCullough et al.(1955), Scott et al. (1962b), Messerly et al. (1967), and Scott andCrowder (1967). The curves were calculated from Eqn. 5 and 6 usingvalues of the a, b, and c coefficients taken from Tables 4 and 5,respectively.

Fig. 23. Vapor pressure curves for saturated liquid and gas cyclic sulfides (Guthrie et al., 1952; White et al., 1952; Osbornand Douslin, 1966): [a] thiacyclopropane (C2H4S), thiacyclobutane (C3H6S), thiacyclopentane (C4H8S), and thiacyclohex-ane (C5H10S), [b] 2-methylthiacyclopentane (C5H10S, solid curve), 3-methylthiacyclopentane (C5H10S, dashed curve), andcyclopentyl-1-thiaethane (C6H12S). The corresponding curve for H2O (Haar et al., 1984) is shown for comparison.

3854 L. Richard

have been drawn through the symbols representing the valuesof a, b, and c for the liquid unsubstituted cyclic sulfides. Anextrapolation of these lines and curve was made to predictvalues of a, b, and c for liquid thiacyclopropane and thiacyclo-heptane. Smooth curves were drawn through the symbols cor-responding to the a, b, and c values generated by regression ofthe ideal gas data for the gases. The lines and curves in Figure26 are consistent with the values of a, b, and c listed in Tables4 and 5, as well as with the solid or dashed curves shown inFigure 25 for compounds XXXV-XXXIX. A regression withEqn. 5 of liquid heat capacity data for 2-methylthiacyclopen-

tane, 3-methylthiacyclopentane, and cyclopentyl-1-thiaethaneresulted in the values of a, b, and c listed in Table 4 and thesolid curves in Figure 25.

The standard molal thermodynamic properties and heat ca-pacity power function coefficients of liquid and gas thiacyclo-pentane (XXXVII) and thiacyclohexane (XXXVIII) listed inTables 4 and 5 were used to retrieve the corresponding prop-erties and coefficients for the cyclic (5)�S and (6)�S sulfidegroups listed in Table 7 according to the group stoichiometriesshown in Table 6. The a, b, and c coefficients for the (5)�Sgroup in the gas state were used to calculate the coefficients

Fig. 24. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of cyclic sulfides as a function of carbon number. The open and filled circles correspondto values reported in the literature (see footnote to Table 2 for references) for cyclic sulfides with odd and even carbonnumbers, respectively. The straight lines and smooth curves highlight the carbon number dependence of the properties,which further depend upon the odd or even value of n for the melting properties.


Fig. 25. Standard molal heat capacity (CP° ) of liquid and gas cyclic sulfides as a function of temperature at 1 bar. The

symbols correspond to experimental or ideal gas values reported by Guthrie et al. (1952), Hubbard et al. (1952), Scott etal. (1953), McCullough et al. (1954b), Stull et al. (1969), and Messerly et al. (1974). The curves have been calculated fromEqn. 5 and 6 using values of a, b, and c taken from Tables 4 and 5, respectively. The solid curves result from regressionsof the data represented by the symbols, while the dashed curves correspond either to predictions or, in the case ofthiacyclohexane, to an extrapolation of the regression curve below the melting point.

listed in Table 5 for 2- and 3-methylthiacyclopentane gasesaccording to

�2- or 3-methylthiacyclopentane � 3�(5)�CH2 � �(5)�CHCH3 � �(5)�S.

(40)

The values of a, b, and c for the (5)�CHCH3 group in Eqn. 40were obtained from those given by Helgeson et al. (1998) formethylcyclopentane gas and the group stoichiometry expres-sion shown in Table 6. Finally, the a, b, and c coefficients forcyclopentyl-1-thiaethane gas in Table 5 were calculated fromthose of methylcyclopentane gas given by Helgeson et al.(1998) and those listed in Table 7 for the –S– (sat) groupaccording to

�cyclopentyl-1-thiaethane � �methylcyclopentane � �–S–(sat) . (41)

4.8. Aromatic Sulfides

Complete calorimetric studies have been reported in theliterature for three aromatic sulfide compounds, including di-phenyl sulfide (XLIII), phenyl-1-thiaethane (or phenyl methylsulfide, XLIV), and poly(thio-1,4-phenylene) (XLV). The va-por pressure curves for phenyl-1-thiaethane and diphenyl sul-fide have been plotted in Figure 27 together with that for H2O.It can be seen in that figure that both of these aromatic sulfidesfall in the gas-phase region of the system H2O.

Experimental heat capacity (CP° ) values for crystalline and

liquid diphenyl sulfide and phenyl-1-thiaethane have been plot-ted as symbols in Figure 28, along with the heat capacity valuesrecommended by Smirnova et al. (1996) for crystalline poly-(thio-1,4-phenylene). Regression of the data for crystalline andliquid diphenyl sulfide and phenyl-1-thiaethane with Eqn. 5

Fig. 26. Coefficients for Eqns. 5 and 6 for liquid and gas cyclic sulfides as a function of carbon number at 1 bar. Thesymbols correspond to values of a, b, and c obtained by regression of experimental or ideal gas data. The straight lines andsmooth curves were drawn to constrain the values of a, b, and c listed in Tables 4 and 5 to be smooth functions of carbonnumber.


resulted in the a, b, and c coefficients listed for these com-pounds in Tables 3 and 4 and the solid curves shown in Figure28. The standard molal enthalpies of formation (�Hf

°) andentropies (S°) at 25°C and 1 bar of liquid diphenyl sulfide andphenyl-1-thiaethane in Table 4 were either taken from theliterature or recalculated from the original combustion studies,but those for the crystals in Table 3 were calculated accordingto the procedure described above for benzenethiol using thestandard molal enthalpies of melting (�Hm) listed in Table 2.The standard molal volumes (V°) of crystalline and liquiddiphenyl sulfide and phenyl-1-thiaethane in Tables 3 and 4were either estimated using the algorithm of Immirzi and Perini(1977), or calculated from the liquid densities and molecularweights listed in Table 2.

The standard molal thermodynamic properties and heat ca-

pacity power function coefficients of crystalline and liquiddiphenyl sulfide and phenyl-1-thiaethane in Tables 3 and 4have been combined with values of the corresponding proper-ties and coefficients for two aromatic groups and a methylgroup taken from Richard and Helgeson (1998) and Helgesonet al. (1998) to calculate the properties and coefficients of twocrystalline and liquid —S—(aro) and —S—(sat/aro) groupslisted in Table 7 according to the group stoichiometries shownin Table 6. Note that for the crystalline –CH3 group, an averagebetween values for –CH3 groups belonging to n-alkanes withodd or even numbers of carbon atoms was calculated for eachproperty and coefficient. The properties and coefficients re-trieved for the —S—(aro) group in the crystalline state wereused together with the equation

�poly(thio-1,4-phenylene) � 4�(6)�CH � 2�(6)�C– � �–S–�aro�

(42)

to calculate those listed in Table 3 for crystalline poly(thio-1,4-phenylene), except the value of the standard molal volumewhich was estimated using the algorithm of Immirizi and Perini(1977). The standard molal entropy (S°) and heat capacity (CP

° )at 25°C and 1 bar calculated from Eqn. 42 differ from thevalues recommended by Smirnova et al. (1996) by 0.18 calmol�1K�1 and 0.09 cal mol�1 K�1, respectively. The esti-mated values of the heat capacity power function coefficientsfor crystalline poly(thio-1,4-phenylene) have been used to-gether with Eqn. 5 to calculate the dashed curve shown inFigure 28, which is also in excellent agreement with the heatcapacity values recommended by Smirnova et al. (1996) for the200 K - 300 K temperature range.

4.9. n-Alkyl Disulfides

Complete investigations of the thermodynamic properties ofliquid and gas 2,3-dithiabutane (XLVI), 3,4-dithiahexane (XL-VII), and 4,5-dithiaoctane (XLVIII) have been reported byScott et al. (1950, 1952b) and Hubbard et al. (1958b). In

Fig. 27. Vapor pressure curves for saturated liquid and gas phenyl-1-thiaethane (C7H8S) and diphenyl sulfide (C12H10S). The data fordrawing these curves were taken from Osborn and Douslin (1966) andSteele et al. (1995). The corresponding curve for H2O (Haar et al.,1984) is shown for comparison.

Fig. 28. Standard molal heat capacitiy (CP° ) of aromatic sulfides as a function of temperature at 1 bar. The symbols

correspond to experimental values reported by Messerly et al. (1974), Steele et al. (1995), and Smirnova et al. (1996). Thecurves have been calculated with Eqn. 5 using values of a, b, and c taken from Tables 3 and 4. The solid curves result fromregressions of the data represented by the symbols, while the dashed curve for poly(thio-1,4-phenylene) represents anindependent prediction using group contributions retrieved in the present study or taken from Richard and Helgeson(1998)—see text.

3858 L. Richard

addition, the standard molal enthalpies of formation (�Hf°) at

25°C and 1 bar of liquid and gas 5,6-dithiadecane (XLIX) havebeen determined by Mackle and McClean (1964). The vaporpressure curves of four saturated liquid and gas n-alkyl disul-fides with carbon number between 2 and 6 are depicted inFigure 29 together with that for H2O. It can be seen in thisfigure that all the n-alkyl disulfides fall in the gas-phase regionof the system H2O. Values reported in the literature for thetemperatures of melting and boiling (Tm and Tv, respectively)and the molal enthalpies of melting and vaporization at Tm andTv (�Hm and �Hv, respectively) have been listed in Table 2 andplotted as a function of carbon number (n) in Figure 30. Aspreviously shown by Helgeson et al. (1998) for other homolo-gous series of organic compounds, the values of both themelting and boiling properties of n-alkyl disulfides adoptsmooth distributions with respect to carbon number, which isillustrated by the dashed curves and straight line drawn in thefigure. No literature values were found for the melting proper-ties of n-alkyl disulfides with odd carbon numbers. Althoughthe boiling properties of organic compounds in a given homol-ogous series are usually insensitive to whether the carbonnumber of the compound is odd or even, the heat of vaporiza-tion (�Hv) calculated by Dreisbach (1961) for 3,4-dithiahep-tane (C5H12S2) departs from the straight line defined by then-alkyl disulfides with even values of n by 130 cal mol�1.

The standard molal enthalpies of formation (�Hf°) and en-

tropies (S°) at 25°C and 1 bar listed in Tables 4 and 5 for liquidand gas n-alkyl disulfides have been calculated using the groupadditivity algorithms of Domalski and Hearing (1993). Thesecalculated values correspond to the straight lines shown inFigure 31. The symbols in this figure represent experimentalvalues of �Hf

° and S° reported in the literature. A comparisonbetween the experimental �Hf

° values and their calculatedcounterparts indicates differences of the order of 200 calmol�1 for the liquids, except for 2,3-dithiabutane for which thedifference is 1.1 kcal mol�1. The differences between theexperimental and calculated values for S° range between 0.4and 1.7 cal mol�1K�1 for the liquids, and between 0.2 and 1.2

cal mol�1K�1 for the gases. The standard molal volumes (V°)at 25°C and 1 bar calculated from the densities and molecularweights in Table 2 for liquid n-alkyl disulfides have also beenplotted as symbols in Figure 31. A linear regression of thevalues represented by these symbols resulted in the equation

V� � 55.60 � 16.93n (43)

and the line shown in Figure 31. Eqn. 43 was used to calculatethe V° values listed for liquid n-alkyl disulfides in Table 4.

Values reported in the literature for the standard molal heatcapacities (CP

° ) of the liquid n-alkyl disulfides XLVI-XLVIIIhave been plotted as a function of temperature at 1 bar in Figure32, and as a function of carbon number at various temperaturesand 1 bar in Figure 33. The CP

° isotherms represented by thesolid curves in Figure 33 have been extrapolated down toconverge at a common fictive carbon number n* � �3.8 forwhich CP

° � a � b � c � 0 at all temperatures. A regressionwith Eqn. 5 of the experimental CP

° data plotted in Figure 32 forliquid 4,5-dithiaoctane (C6H14S2) resulted in the values of a, b,and c listed for this compound in Table 4 and the symbolsshown in Figure 34. The dashed curves in this figure have beendrawn in such a way to fit the experimental heat capacities ofliquid 2,3-dithiabutane (C2H6S2) and 3,4-dithiahexane(C4H10S2) shown in Figure 32, with the constraint that thevalues of a, b, and c must be equal to zero at n* � �3.8. Thedashed curves have been extrapolated from n � 6 to n � 8.Above this value, –CH2– increments given by Helgeson et al.(1998) have been used to calculate the a, b, and c coefficientsof liquid n-alkyl disulfides with n � 8 according to

�CnH2(n�1)S2 � �C8H18S2 � �–CH2–,Cn�2H2(n�3). (44)

Ideal gas heat capacities reported by Hubbard et al. (1958b) asa function of temperature at 1 bar for n-alkyl disulfide gaseshave been plotted as symbols in Figure 35. Regression withEqn. 6 of the data for 2,3-dithiabutane and 4,5-dithiaoctane gasresulted in the values of a, b, and c listed in Table 5 for thesetwo compounds, and the symbols shown in Figure 36. Thesmooth curves drawn in this figure correspond to the valueslisted in Table 5 for n-alkyl disulfide gases with 2 � n � 6. Thecoefficients listed for 3,4-dithiahexane were used to calculatethe dashed curve shown in Figure 35. For n-alkyl disulfidegases with n � 6, the values of a, b, and c were calculated usinggroup contributions given by Helgeson et al. (1998) for –CH2–aliphatic groups, in the manner described above for the n-alkylsulfide gases.

Finally, the standard molal thermodynamic properties andheat capacity power function coefficients of liquid and gas2,3-dithiabutane in Tables 4 and 5 were combined with thosegiven by Helgeson et al. (1998) for the methyl –CH3 group andthe group stoichiometry expression shown in Table 6 to retrievethe properties and coefficients listed in Table 7 for a –S–S–(sat)disulfide group in the liquid and gas state.

4.10. Thiophenics

Thermodynamic studies have been reported in the literaturefor seven thiophenic compounds, including thiophene (L),2-methylthiophene (LI), 3-methylthiophene (LII), 2,5-dimeth-

Fig. 29. Vapor pressure curves for saturated liquid and gas 2,3-dithiabutane (C2H6S2), 3,4-dithiahexane (C4H10S2), 3,4-dithiaheptane(C5H12S2), and 4,5-dithiaoctane (C6H14S2). The data for drawing thesecurves were taken from White et al. (1952). The corresponding curvefor H2O (Haar et al., 1984) is shown for comparison.


ylthiophene (LIII), 2-isopropylthiophene (LIV), benzo[b]thio-phene (LV), and dibenzo[b,d]thiophene (LVI).6

The vapor pressure curves for the seven saturated liquid andgas thiophenic compounds (L-LVI) are depicted in Figure 37,

together with the curve for H2O. It can be seen in this figurethat all the curves fall in the gas-phase region of the systemH2O, except that for the parent compound thiophene. Valuesreported in the literature for the temperatures of melting (Tm,Pr

)and boiling (Tv,Pr

) and the standard molal enthalpies of melting(�Hm,Pr

) and vaporization (�Hv,Pr) of these thiophenic com-

pounds have been plotted as a function of carbon number (n) inFigure 38. It can be seen in this figure that both the melting and

6 Waddington et al. (1949), McCullough et al. (1953b), Finke et al.(1954), Sunner (1955), Pennington et al. (1956), Carlson and Westrum(1965), Good (1972), Chirico et al. (1991a,b).

Fig. 30. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of n-alkyl disulfides as a function of carbon number. The open and filled circlescorrespond to values reported in the literature (see footnote to Table 2 for references) for n-alkyl disulfides with odd andeven carbon numbers, respectively. The straight lines and smooth curves highlight the carbon number dependence of theproperties.

3860 L. Richard

boiling properties of thiophene, benzo[b]thiophene, and diben-zo[b,d]thiophene plot on smooth curves, as do the boilingproperties of thiophene, 2-methylthiophene, and 2,5-dimethyl-thiophene.

The standard molal enthalpies of formation (�Hf°) at 25°C

and 1 bar of crystalline benzo[b]thiophene and dibenzo[b,d-]thiophene in Table 3, as well as those of liquid thiophene, 2-and 3-methylthiophene, and 2-isopropylthiophene in Table 4were recalculated from the original combustion studies as de-scribed above. The �Hf

° values of these four liquids werecombined with values reported in the literature for their stan-dard molal enthalpies of vaporization (�Hv

°) at 25°C and 1 barto calculate from Eqn. 15 the standard molal enthalpies offormation listed in Table 5 for their gas state counterparts.

Based on an analogy recognizing that both methylated ben-zenes and methylated thiophenes are aromatic compounds withresembling structures and physical properties (e.g., Carlson andWestrum, 1965), as well as on the observation that the standardmolal enthalpy of formation (�Hf

°) of liquid 1,3-dimethylben-zene can be predicted within 100 cal mol�1 of its experimentalvalue from those of benzene and toluene according to

�Hf,1,3-dimethylbenzene� � �Hf,toluene

� � ��Hf,toluene� � �Hf,benzene

� �,

(45)

the �Hf° value listed in Table 4 for liquid 2,5-dimethylthio-

phene was estimated from the relation


of carbon number for n-alkyl disulfide liquids and gases. The symbols for �Hf° and S° correspond to literature values

reported by Scott et al. (1950, 1952b), Hubbard et al. (1958b), and Mackle and McClean (1964). The lines correspond to�Hf

° and S° values calculated using group additivity algorithms given by Domalski and Hearing (1993). The symbols forV° correspond to values calculated from the densities and molecular weights listed in Table 2. A linear regression of thesevalues resulted in the line shown in the figure.


�2,5-dimethylthiophene � �2-methylthiophene � ��2-methylthiophene

� �thiophene�. (46)

The standard molal enthalpy of formation (�Hf°) at 25°C and 1

bar of 2,5-dimethylthiophene gas in Table 5 was taken from theliterature, as were the standard molal entropies (S°) at 25°C and1 bar of crystalline benzo[b]thiophene and dibenzo[b,d]thio-phene in Table 3 and those of liquid thiophene, 2- and 3-meth-ylthiophene, and 2,5-dimethylthiophene in Table 4. The valuesof S° listed in Tables 4 and 5 for 2-isopropylthiophene liquidand gas and that of �Hf

° in Table 5 were estimated from

�2-isopropylthiophene � �2-methylthiophene � �–CH3 � �–CH(CH3)2 (47)

using the values given by Helgeson et al. (1998) for thestandard molal enthalpy of formation and standard molal en-tropy for the �CH3 and �CH(CH3)2 groups in the liquid andgas states. The standard molal entropies of the other thiophenicgases in Table 5 were taken from the literature. Finally, thestandard molal enthalpies of formation (�Hf

°) and standardmolal entropies (S°) at 25°C and 1 bar of metastable crystallinethiophene in Table 3 and of metastable liquid benzo[b]thio-phene and dibenzo[b,d]thiophene in Table 4 were calculatedfrom the corresponding properties for their stable phase coun-terparts at the melting point, the standard molal enthalpies ofmelting (�Hm

° ) in Table 2, and the heat capacity power functioncoefficients listed in Tables 3 and 4 (see below) using theprocedure described above for benzenethiol. Note that, forcrystalline thiophene, the change in heat of 152.4 cal mol�1

associated with the lambda transition (see footnote�) at 171.6 Kwas included in the calculation, which resulted in a total heat ofmelting of 1367.9 cal mol�1.

The values listed in Table 3 for the standard molal volumes(V°) at 25°C and 1 bar of the thiophenic crystals were estimatedusing the algorithm of Immirzi and Perini (1977). Those listedin Table 4 for liquid thiophene, 2- and 3-methylthiophene,2,5-dimethylthiophene, and 2-isopropylthiophene were calcu-lated from the densities and molecular weights listed in Table2. Experimental densities at various temperatures have beenreported in the literature for liquid benzo[b]thiophene. Thesedensity values have been converted to their standard molalvolume (VPr

°,T) counterparts and plotted as symbols in Figure

39. As the data corresponding to the densities reported byHaines et al. (1956) do not seem consistent with the tempera-ture dependence exhibited by the data from other sources, theywere not included in the regression which resulted in

V� � 113.2 � 0.115T, (48)

the straight line shown in Figure 39, and the V° value of liquidbenzo[b]thiophene at 25°C and 1 bar in Table 4. The lattervalue was used together with that of liquid thiophene and

Vdibenzo b,d�thiophene�l �

� � Vbenzo b�thiophene�l �

� � �Vbenzo b�thiophene�l �

�

� Vthiophene�l �

� � (49)

to estimate the standard molal volume (V°) at 25°C and 1 barof dibenzo[b,d]thiophene liquid in Table 4.

Experimental or ideal gas values reported in the literature forthe standard molal heat capacitiy (CP

° ) of thiophenic com-pounds as a function of temperature have been plotted assymbols in Figure 40. Regression of these values with Eqn. 5for the crystals and liquids, and with Eqn. 6 for the gasesresulted in the a, b, and c coefficients listed in Tables 3, 4, and5, and the solid lines and curves shown in the figure, except forcrystalline thiophene for which a straight line was tentativelydrawn through the data between 140 K and 215 K, whichare respectively 32 K below and 43 K above the lambdatransition mentioned above. Finally, the dashed curves in Fig-ure 40 corresponding to predicted values of the standard molalheat capacities of 2,5-dimethylthiophene gas and 2-isopropyl-thiophene liquid and gas, which have been calculated from

Fig. 32. Standard molal heat capacities (CP° ) of liquid n-alkyl disul-

fides as a function of temperature at 1 bar. The symbols correspond toexperimental data reported in the literature. The curves were generatedfrom Eqn. 5 using values of a, b, and c listed in Table 4.

Fig. 33. Standard molal heat capacities (CP° ) of liquid n-alkyl disul-

fides as a function of carbon number (n) at various temperatures at 1bar. The symbols correspond to experimental data reported in theliterature, but the curves were generated from Eqn. 5 using values of a,b, and c listed in Table 4 for values of n � 2. Below n � 2, the curveswere extrapolated to intersect at a common fictive carbon number n*(see text).

3862 L. Richard

Eqns. 5 and 6 using values of the a, b, and c coefficientsestimated from Eqns. 46 and 47.

4.11. Thianthrene

The vapor pressure curve for saturated liquid and gas thi-anthrene (LVII) is depicted in Figure 41 together with that forH2O. It can be seen in this figure that the curve for thianthrenefalls in the gas phase region of the system H2O. The standardmolal entropy (S°), volume (V°), and enthalpy of formation(�Hf

°) at 25°C and 1 bar of crystalline thianthrene in Table 3were respectively taken from the literature, obtained from thedensity and molecular weight listed in Table 2, and recalculatedfrom the original combustion data. The values of �Hf

° and S° ofliquid thianthrene in Table 4 were calculated in the manner

described above for benzenethiol from the corresponding val-ues for the crystal at the melting point, the standard molalenthalpy of melting (�Hm

° ) listed in Table 2, and the heatcapacity power function coefficients of crystalline and liquidthianthrene listed in Tables 3 and 4. High-temperature densitydata reported by Steele et al. (1993) for liquid thianthrene havebeen converted to their standard molal volume counterparts andplotted as symbols in Figure 42. A linear regression of the datarepresented by the symbols resulted in the equation

V� � 121.0 � 0.1424T, (50)

which was used to calculate the standard molal volume at 25°Cand 1 bar of liquid thianthrene in Table 4. Experimental valuesof the standard molal heat capacity (CP

° ) of crystalline andliquid thianthrene have been plotted as a function of tempera-ture at 1 bar in Figure 43. Regression with Eqn. 5 of the datarepresented by symbols resulted in the values of the a, b, and ccoefficients listed in Tables 3 and 4 for crystalline and liquidthianthrene, and the regression curves shown in Figure 43.

Finally, the standard molal thermodynamic properties andheat capacity power function coefficients of crystalline andliquid thianthrene in Tables 3 and 4 have been combined withthose for crystalline and liquid aromatic hydrocarbon groupsgiven by Richard and Helgeson (1998) to retrieve the propertiesand coefficients of the crystalline and liquid aromatic (6)�Sgroups in Table 7 according to the group stoichiometry shownin Table 6.

5. CALCULATION OF THE THERMODYNAMICPROPERTIES OF LIQUID THIOLANES, THIANES,

THIOPHENES, BENZO[b]-THIOPHENES, ANDDIBENZO[b,d]THIOPHENES

The thermodynamic properties and heat capacity coefficientsof liquid long-chain n-alkylthiolanes, n-alkylthianes, n-alkyl-thiophenes, and those of methylated benzo[b]thiophenes anddibenzo[b,d]thiophenes can be estimated from group additivityrelations using the properties and cofficients of their short-

Fig. 34. Coefficients for Eqn. 5 for n-alkyl disulfide liquids as a function of carbon number at 1 bar. The symbolscorrespond to values of a, b, and c obtained by regression of experimental data reported for 4,5-dithiaoctane liquid. The solidcurves correspond to values of a, b, and c calculated by adding –CH2– n-alkane increments to the values for 5,6-dithiadecane. The dashed curves were adjusted by fitting experimental heat capacity values for n-alkyl disulfide liquids withn � 8 and the constraint that a � b � c � CP

° � 0 at n* � �3.8 (see text).

Fig. 35. Standard molal heat capacities (CP° ) of gas n-alkyl disulfides

as a function of temperature at 1 bar. The symbols correspond to idealgas heat capacities reported by Hubbard et al. (1958b). The curves werecalculated using Eqn. 6 together with values of a, b, and c listed inTable 5.


chain or unsubstituted counterparts in Table 4 together withthose of hydrocarbon groups reported by Helgeson et al. (1998)and Richard and Helgeson (1998). Group additivity algorithmsfor calculating the properties and coefficients of 2,5-di-n-alkyl-thiolanes, 2,6-di-n-alkylthianes, and 2,5-di-n-alkylthiophenesare presented in Tables 8–10. The standard molal thermody-namic properties and heat capacity power function coefficientsof the methylated benzo[b]thiophenes and dibenzo[b,d]thio-phenes are listed in Tables 11 and 12.

5.1. n-Alkylthiolanes and n-Alkylthianes

The thermodynamic properties and heat capacity powerfunction coefficients of liquid thiacyclopentane, thiacyclohex-ane, and 2-methylthiacyclopentane in Tables 8 and 9 have been

retrieved in the previous section from experimental data re-ported in the literature. The standard molal volumes (V°) at25°C and 1 bar of liquid cis- and trans-2,5-dimethylthiacyclo-pentane in Table 8 were calculated from density values listed inthe TRC Thermodynamic Tables (1986). The standard molalenthalpy of formation (�Hf

°), standard molal entropy (S°), andheat capacity power function coefficients of trans-2,5-dimeth-ylthiacyclopentane were estimated from the relation

�trans-2,5-dimethylthiacyclopentane� � �2-methylthiacyclopentane

�

� ��trans-1,3-dimethylcyclopentane� � �methylcyclopentane

� � (51)

using thermodynamic data reported by Johnson et al. (1949),Gross et al. (1953), and Good and Smith (1969). This assump-

Fig. 36. Coefficients for Eqn. 6 for n-alkyl disulfide gases as a function of carbon number at 1 bar. The symbolscorrespond to values of a, b, and c obtained by regression of ideal gas heat capacity data reported in the literature. Smoothcurves have been drawn through these symbols, and extrapolated above n � 6 by adding –CH2– increments taken fromHelgeson et al. (1998) to the regression values of a, b, and c obtained for 4,5-dithiaoctane—see text.

Fig. 37. Vapor pressure curves for saturated liquid and gas [a] thiophene (C4H4S), 2-methylthiophene (C5H6S), and2,5-dimethylthiophene (C6H8S), [b] 3-methylthiophene (C5H6S), 2-isopropylthiophene (C7H10S), benzo[b]thiophene(C8H6S), and dibenzo[b,d]thiophene (C12H8S). The data for drawing these curves were taken from White et al. (1952),Dreisbach (1955), Osborn and Scott (1980), and Chirico et al. (1991a,b). The corresponding curve for H2O (Haar et al.,1984) is shown for comparison.

3864 L. Richard

tion is based on the observation that the standard molal en-thalpy of formation (�Hf

°) and standard molal volume (V°) oftrans-1,3-dimethylcyclopentane can be predicted to within 120cal mol�1 and 0.4 cm3 mol�1, respectively, of their experi-mental counterparts by considering

�trans-1,3-dimethylcyclopentane� � �methylcyclopentane

�

� ��methylcyclopentane� � �cyclopentane

� �. (52)

The standard molal enthalpy of formation (�Hf°) of cis-2,5-

dimethylthiacyclopentane was calculated from

�Hf,cis-2,5-dimethylthiacyclopentane� � �Hf,2-methylthiacyclopentane

�

� ��Hf,cis-1,3-dimethylcyclopentane� � �Hf,methylcyclopentane

� �. (53)

In the absence of experimental heat capacity data for cis-1,3-dimethylcyclopentane, no distinction could be made between the

Fig. 38. Temperatures of melting (Tm) and boiling (Tv) at one atmosphere and standard molal enthalpies of melting (�Hm)at Tm and vaporization (�Hv) at Tv of thiophenic compounds as a function of carbon number. The open and filled circlescorrespond to values reported in the literature (see footnote to Table 2 for references) for thiophenic compounds with oddand even carbon numbers, respectively. The abbreviations on the symbols refer to thiophene (tp), 2-methylthiophene (2mtp),3-methylthiophene (3mtp), 2,5-dimethylthiophene (25dmtp), 2-isopropyl-thiophene (2iptp), benzo[b]thiophene (btp), anddibenzo[b,d]thiophene (dbtp). The dashed curves were drawn to highlight the carbon number dependence of the melting andboiling properties of thiophene, benzo[b]thiophene, and dibenzo[b,d]thiophene. The solid curves indicate such a dependencefor the boiling properties of thiophene, 2-methylthiophene, and 2,5-dimethylthiophene.


standard molal entropies (S°) and heat capacity power functioncoefficients of cis- and trans-2,5-dimethylthiacyclopentane.

In the case of the cyclohexane ring, the conformations withsubstituents in equatorial positions are preferred over thosewith substituents in axial positions. Consequently, the cis iso-mer of 1,3-dimethylcyclohexane is more stable than the trans isomer,

Table 8. Group contributions for calculating the standard molal thermodynamic properties and heat capacity power function coefficients of liquid2-n-alkylthiacyclopentanes and 2,5-di-n-alkylthiacyclopentanes.

Compound Formula �G°fa,f �H°f

a S°b V°c C°Pb,g ab bd 10�3 ce 105

Thiacyclopentane C4H8S 9213 �17147 49.67 88.7 33.55 11.33 68.5 1.6002-Methylthiacyclopentane C5H10S 8355 �25054 58.63 107.5 41.07 15.25 81.1 1.456cis-2,5-Dimethylthiacyclopentane C6H12S 9113 �32324 64.31 126.6h 48.19 19.35 91.7 1.334trans-2,5-Dimethylthiacyclopentane C6H12S 8623 �32814 64.31 127.1h 48.19 19.35 91.7 1.334OCH2O(ethylthiacyclopentane) 1786 �5629 7.74 17.0 6.76 0.41 19.1 0.580OCH2O(n-propylthiacyclopentane) 1265 �6150 7.74 16.9 7.11 1.36 17.1 0.580OCH2O(n-butylthiacyclopentane) 1265 �6150 7.74 16.9 6.85 2.23 13.3 0.580OCH2O(n-pentylthiacyclopentane) 1265 �6150 7.74 16.9 7.19 3.11 11.6 0.550OCH2O(n-hexylthiacyclopentane) 1265 �6150 7.74 17.0 7.25 3.00 12.0 0.600OCH2O(n-heptylthiacyclopentane) 1265 �6150 7.74 16.9 7.01 3.10 11.0 0.560OCH2O(n-octylthiacyclopentane) 1265 �6150 7.74 17.0 7.33 3.10 12.0 0.580OCH2O(n-nonylthiacyclopentane) 1265 �6150 7.74 17.1 7.33 3.10 12.0 0.580OCH2O(n-decylthiacyclopentane) 1265 �6150 7.74 17.0 7.09 2.98 11.5 0.610OCH2O(n-undecylthiacyclopentane) 1265 �6150 7.74 17.0 7.07 3.02 11.5 0.550OCH2O(n-dodecylthiacyclopentane)i 1265 �6150 7.74 17.0 7.45 3.20 12.0 0.600

Sample calculationtrans-2-n-Butyl-5-n-

decylthiacyclopentaneC18H36S 24827 �105572 157.19 330.6 132.83 45.74 260.8 8.294

a Cal mol�1 b Cal mol�1 K�1 c Cm3 mol�1 d Cal mol�1 K�2 e Cal K mol�1 f Calculated from Eqn. 13 g Calculated from Eqn. 5 h Calculated froma density value at 25°C listed in the TRC Thermodynamic Tables (1986) and a molecular weight of 116.225 G mol�1 i The properties and coefficientsof subsequent OCH2O groups in longer alkyl chains are taken to be the same as those for the OCH2O group in n-dodecyclopentane

Table 9. Group contributions for calculating the standard molal thermodynamic properties and heat capacity power function coefficients of liquid2-n-alkylthiacyclohexanes and 2,6-di-n-alkylthiacyclohexanes.



Thiacyclohexane C5H10S 10051 �25288 52.16 104.2 39.05 15.23 79.5 0.1002-Methylthiacyclohexane C6H12S 8558 �33398 62.57 123.9h 45.79 12.45 101.8 2.652cis-2,6-Dimethylthiacyclohexane C7H14S 8677 �41238 68.48 142.9 51.71 10.52 125.3 3.403trans-2,6-Dimethylthiacyclohexane C7H14S 10138 �39518 69.35 139.4 52.55 6.66 136.1 4.725OCH2O(ethylthiacyclohexane) 1787 �5628 7.74 16.9 6.56 �2.15 26.0 0.850OCH2O(n-propylthiacyclohexane) 1265 �6150 7.74 16.9 7.07 �0.75 23.0 0.860OCH2O(n-butylthiacyclohexane) 1265 �6150 7.74 16.9 6.97 0.35 19.0 0.850OCH2O(n-pentylthiacyclohexane) 1265 �6150 7.74 17.0 7.18 0.55 19.0 0.860OCH2O(n-hexylthiacyclohexane) 1265 �6150 7.74 16.9 7.62 1.00 19.0 0.850OCH2O(n-heptylthiacyclohexane) 1265 �6150 7.74 17.0 7.18 1.45 16.0 0.850OCH2O(n-octylthiacyclohexane) 1265 �6150 7.74 17.1 7.04 1.60 15.0 0.860OCH2O(n-nonylthiacyclohexane) 1265 �6150 7.74 17.0 7.23 2.10 14.0 0.850OCH2O(n-decylthiacyclohexane) 1265 �6150 7.74 17.0 6.93 2.40 12.0 0.850OCH2O(n-undecylthiacyclohexane) 1265 �6150 7.74 17.0 7.95 3.70 11.0 0.860OCH2O(n-dodecylthiacyclohexane)i 1265 �6150 7.74 17.0 8.89 4.95 10.0 0.850

Sample calculationcis-2-n-Dodecyl-6-methylthia-

cyclohexaneC18H36S 23098 �108366 153.62 329.6 132.33 25.72 309.3 12.793

a Cal mol�1 b Cal mol�1K�1 c Cm3mol�1 d Cal mol�1K�2 e Cal K mol�1 f Calcculated from Eqn. 13 g Calculated from Eqn. 5 h Calculated froma density value at 25°C listed in the TRC Thermodynamic Tables (1986) and a molecular weight of 116.225 G mol�1 i The properties and coefficientsof subsequent OCH2O groups in longer alkyl chains are taken to be the same as those for the OCH2O group in n-dodecylcyclohexane

3866 L. Richard

as nonbonded interactions are minimized for the cis conforma-tion. This is in agreement with the observation that both thestandard molal enthalpy of formation (�Hf

°) and the standardmolal volume (V°) of cis-1,3-dimethylcyclohexane can be pre-dicted from

�cis-1,3-dimethylcyclohexane� � �methylcyclohexane

�

� ��methylcyclohexane� � �cyclohexane

� � (54)

Fig. 39. Standard molal volume (V°) of benzo[b]thiophene liquid asa function of temperature at 1 bar. The symbols correspond to exper-imental values reported by von Auwers (1915), Haines et al. (1956),Davis and Gottlieb (1963), Chirico et al. (1991a), and the Handbook ofChemistry and Physics (1992). The straight line was calculated fromEqn. 48.

Fig. 40. Standard molal heat capacities (CP° ) of thiophenic componds as a function of temperature at 1 bar. The symbols

correspond to experimental or ideal gas values reported by Waddington et al. (1949), McCullough et al. (1953b), Finke etal. (1954), Pennington et al. (1956), Carlson and Westrum (1965), and Chirico et al. (1991a,b). The straight lines and curveswere calculated using Eqns. 5 and 6 together with values of a, b, and c listed in Tables 3 to 5.


within 270 cal mol�1 and 0.7 cm3 mol�1 of their experimentalcounterparts. The standard molal thermodynamic propertiesand heat capacity power function coefficients of liquid 2-meth-ylthiacyclohexane, and cis- and trans-2,6-dimethylthiacyclo-hexane in Table 9 were calculated according to

�2-methylthiacyclohexane� � �thiacyclohexane

�

� ��methylcyclohexane� � �cyclohexane

� �, (55)

�cis-2,6-dimethylthiacyclohexane� � �2-methylthiacyclohexane

�

� ��cis-2,6-methylcyclohexane� � �methylcyclohexane

� �, (56)

and

�trans-2,6-dimethylthiacyclohexane� � �2-methylthiacyclohexane

�

� ��trans-2,6-methylcyclohexane� � �methylcyclohexane

� � (57)

using thermodynamic data reported by Ruehrwein and Huff-man (1943), Douslin and Huffman (1946), Johnson et al. (1946,1947), Huffman et al. (1949), and Good and Smith (1969).

The standard molal thermodynamic properties and heat

capacity power function coefficients of liquid 2-methylthia-cyclopentane, 2-methylthiacyclohexane, cis- and trans-2,5-dimethylthiacyclopentane, and cis- and trans-2,6-dimethyl-thiacyclohexane in Tables 8 and 9 can be combined withthose of —CH2— groups in the side chains of liquid n-alkylcyclopentanes and n-alkylcyclohexanes given by Rich-ard and Helgeson (1998) to estimate the corresponding prop-erties and coefficients of long-chain 2-n-alkylthiacyclopentanes,2-n-alkylthiacyclohexanes, cis- and trans-2,5-di-n-alkylthiacy-clopentanes, and cis- and trans-2,6-di-n-alkylthiacyclohexanes.Examples of such estimates are shown in Tables 8 and 9 fortrans-2-n-butyl-5-n-decylthiacyclopentane and cis-2-n-dode-cyl-6-methylthiacyclohexane.

5.2. n-Alkylthiophenes

The thermodynamic properties and heat capacity coefficientsof liquid thiophene, 2-methylthiophene, and 2,5-dimethylthio-phene listed in Table 10 have been retrieved from experimentaldata reported in the literature as described in the previoussection of this communication. Due to similarities in the phys-ical properties of alkylthiophenes and alkylbenzenes (Carlsonand Westrum, 1965), it is expected that thermodynamic prop-erties and heat capacity coefficients of 2-methylthiophene and2,5-dimethylthiophene can be used together with those of—CH2—groups in the side chains of n-alkylbenzene liquidsgiven by Helgeson et al. (1998) to estimate the properties andcoefficients of long-chain 2-n-alkylthiophenes and 2,5-di-n-alkylthiophenes. An example calculation is shown in Table 10for 2-n-tridecyl-5-n-propylthiophene.

5.3. Methylated Benzo[b]thiophenes andDibenzo[b,d]thiophenes

The standard molal thermodynamic properties and heat ca-pacity power function coefficients of liquid benzo[b]thiopheneand dibenzo[b,d]thiophene listed in Tables 11 and 12 have beenretrieved from experimental data reported in the literature in the

Fig. 41. Vapor pressure curve for saturated liquid and gas thianthrene(C12H8S2). The data for drawing this curve were taken from Steele etal. (1993). The corresponding curve for H2O (Haar et al., 1984) isshown for comparison.

Fig. 42. Standard molal volume (V°) of thianthrene liquid as afunction of temperature at 1 bar. The symbols correspond to experi-mental values reported by Steele et al. (1993). The straight line wascalculated from Eqn. 50.

Fig. 43. Standard molal heat capacity (CP° ) of crystalline and liquid

thianthrene as a function of temperature at 1 bar. The symbols corre-spond to experimental values reported by Steele et al. (1993). Thestraight line for the liquid and the curve for the crystal were calculatedusing Eqn. 5 together with the values of a, b, and c listed in Tables 3and 4.

3868 L. Richard

maner described above. These properties and coefficients havebeen combined together with those listed in Tables 4 and 10 forliquid thiophene, 2-methylthiophene and 3-methylthiophene,and those of liquid aromatic groups given by Richard andHelgeson (1998) to calculate the properties and coefficientslisted in Tables 11 and 12 for the methyl- and dimethylbenzo-[b]thiophenes and -dibenzo[b,d]thiophenes.

6. UNCERTAINTIES

The uncertainties associated with the standard molal thermo-dynamic properties of the organic sulfur compounds listed inTables 3-5 and 8–12 are summarized below. When experimen-

tal values have been selected from the literature for the standardmolal enthalpies of formation at 25°C and 1 bar (�Hf

°), theuncertainties associated with these values are of the order of150 to 450 cal mol�1 for the solids and the liquids, and 150 to500 cal mol�1 for the gases. Except for the few exceptionsmentioned in the text, �Hf

° values calculated using the algo-rithms of Domalski and Hearing (1993) are within 1 kcal mol�1

of their experimental counterparts for both the liquids andgases, which should also be the case for �Hf

° values estimatedusing algorithms developed in the present study based oncomparisons with hydrocarbon homologues. The uncertaintiesreported in the literature for experimental values of the standardmolal entropy (S°) at 25°C and 1 bar of organic sulfur liquids

Table 10. Group contributions for calculating the standard molal thermodynamic properties and heat capacity power function coefficients of liquid2-n-alkylthiophenes and 2,5-di-n-alkylthiophenes.



Thiophene C4H4S 28664 19029 43.30 79.5 29.61 12.78 51.4 1.3382-Methylthiophene C5H6S 27443 10747 52.22 96.8 35.79 16.27 59.3 1.6362,5-Dimethylthiophene C6H8S 27013 2465 58.49 114.5 42.61 16.74 74.7 3.210OCH2O(ethylthiophene) 1407 �5848h 8.27h 25.3 6.79 1.36 16.1 0.564OCH2O(n-propylthiophene) 1265 �6150 7.74 17.1 6.78 1.31 16.0 0.620OCH2O(n-butylthiophene) 1265 �6150 7.74 17.0 6.80 1.33 15.7 0.705OCH2O(n-pentylthiophene) 1265 �6150 7.74 17.0 6.78 1.48 14.8 0.787OCH2O(n-hexylthiophene) 1265 �6150 7.74 17.1 6.92 2.07 13.3 0.787OCH2O(n-heptylthiophene) 1265 �6150 7.74 17.0 7.02 2.62 11.8 0.787OCH2O(n-octylthiophene) 1265 �6150 7.74 17.1 7.10 3.08 10.5 0.787OCH2O(n-nonylthiophene) 1265 �6150 7.74 17.0 7.21 3.43 9.7 0.787OCH2O(n-decylthiophene) 1265 �6150 7.74 17.0 7.28 3.65 9.2 0.787OCH2O(n-undecylthiophene) 1265 �6150 7.74 17.1 7.39 3.73 9.3 0.787OCH2O(n-dodecylthiophene) 1265 �6150 7.74 17.0 7.46 3.68 9.7 0.787OCH2O(n-tridecylthiophene) 1265 �6150 7.74 17.0 7.54 3.52 10.5 0.787OCH2O(n-tetradecylthiophene)i 1265 �6150 7.74 17.0 7.59 3.28 11.5 0.787

Sample calculation2-n-Tridecyl-5-n-propylthiophene C20H36S 44940 �83031 167.91 369.6 141.26 50.67 253.4 13.366

a Cal mol�1 b Cal mol�1K�1 c Cm3mol�1 d Cal mol�1K�2 e Cal K mol�1 f Calculated from Eqn. 13 g Calculated from Eqn. 5 h Value calculatedfrom the difference between those listed by Richard and Helgeson (1998) for toluene and Helgeson et al. (1998) for ethylbenzene i The propertiesand coefficients of subsequent OCH2O groups in longer alkyl chains are taken to be the same as those for the OCH2O group in n-tetradecylthiophene.

Table 11. Standard molal thermodynamic properties and heat capacity power function coefficients of liquid methylated benzo[b]thiophenes.



Benzo[b]thiophene C8H6S 45324 27180 51.48 116.0 44.91 25.45 68.8 �0.9342-Methylbenzo[b]thiophene C9H8S 44104 18898 60.40 133.3 51.09 28.94 76.7 �0.6363-Methylbenzo[b]thiophene C9H8S 43747 18532 60.37 133.1 51.30 27.89 79.7 �0.3124- or 7-Methylbenzo[b]thiophene C9H8S 42986 17780 60.40 130.9 51.80 30.25 75.8 �0.9345- or 6-Methylbenzo[b]thiophene C9H8S 43088 17581 59.39 133.0 51.36 28.35 80.7 �0.9342,3-Dimethylbenzo[b]thiophene C10H10S 43304 11027 69.29 151.1 59.80 29.29 95.4 1.8382,4- or 2,7-Dimethylbenzo[b]thiophene C10H10S 41766 9498 69.32 148.2 57.98 33.74 83.7 �0.6362,5- or 2,6-Dimethylbenzo[b]thiophene C10H10S 41868 9299 68.31 150.3 57.54 31.84 88.6 �0.6363,4- or 3,7-Dimethylbenzo[b]thiophene C10H10S 41409 9132 69.29 148.0 58.19 32.69 86.7 �0.3123,5- or 3,6-Dimethylbenzo[b]thiophene C10H10S 41511 8933 68.28 150.1 57.74 30.79 91.6 �0.3124,5- or 6,7-Dimethylbenzo[b]thiophene C10H10S 41527 8958 68.31 148.6 60.57 31.06 95.5 0.9184,6- or 5,7-Dimethylbenzo[b]thiophene C10H10S 40750 8181 68.31 147.9 58.25 33.15 87.7 �0.9344,7-Dimethylbenzo[b]thiophene C10H10S 40648 8380 69.32 145.8 58.69 35.05 82.8 �0.9345,6-Dimethylbenzo[b]thiophene C10H10S 41629 8759 67.30 150.7 60.13 29.16 100.4 0.918

a Cal mol�1 b Cal mol�1K�1 c Cm3mol�1 d Cal mol�1K�2 e Cal K mol�1 f Calculated from Eqn. 13 g Calculated from Eqn. 5.


and gases are usually less then 0.2 cal mol�1K�1, but thoseassociated to predicted values using algorithms either devel-oped in the present study or taken from Domalski and Hearing(1993) are usually less than 2 cal mol�1K�1. When a compar-ison with experimental data is possible, similar uncertaintiesare found for the standard molal heat capacities (CP

° ) as afunction of temperature at 1 bar. Finally, uncertainties associ-ated with values of the standard molal volume (V°) calculatedwith the PFGC equation of state are expected to be of the orderof 5% or less under the conditions of temperature and pressuretypical of sedimentary basins.

7. CONCLUDING REMARKS

The thermodynamic properties of crystalline, liquid, and gasorganic sulfur compounds retrieved in the present study can beused in theoretical calculations to characterize from a thermo-dynamic point of view geochemical reactions involving theseorganic sulfur compounds and other hydrocarbon species insulfur-rich kerogens and bitumens, aqueous fluids, hydrogensulfide and minerals in hydrocarbon reservoir and source rocks.These thermodynamic properties will be incorporated in thedatabase of the ORGANOBIOGEOTHERM software package(Helgeson et al., 1998) to facilitate calculation of the equilib-rium constants of the reactions as a function of temperature andpressure. These calculations can provide constraints on suchimportant processes as the early generation of petroleum fromsulfur-rich kerogens or the change in the distribution of organicsulfur compounds with increasing oil maturity.

Acknowledgments—It is my pleasure to dedicate this paper to ProfessorHarold C. Helgeson on the occasion of his seventieth birthday, and tothank him sincerely for the unconditional friendship, unlimited scien-tific and moral support, and inspirational teaching of geochemistry heprovided me with over the past eight years. Part of the research reportedin the present study was carried out during my stays at Elf Exploration-Production (Pau) and at the Centre de Geochimie de la Surface (Stras-bourg) with funding from the European Commission (contractn°FMBICT960953) and the Societe de Secours des Amis des Sciences(Paris). In this regard, I wish to thank Olivier Brevart and BertrandFritz for their hospitality and for giving me space and access to thecomputational facilities in their respective laboratories. Additionalfunding to H.C. Helgeson from the United States Department of Energy(DOE Grant DE-FG03 to 85ER13419), the National Science Founda-tion (NSF Grant EAR 9613753), the donors of the Petroleum ResearchFund, administered by the American Chemical Society (ACS-PRF

grant 36467-AC2), and the Committee on Research at the University ofCalifornia (Berkeley) made it possible to bring this project to comple-tion. Constructive reviews by Thomas Giordano, Richard Kettler, andMitchell Schulte, as well as editorial handling by Scott Wood areappreciated.

Associate editor: S. A. Wood

REFERENCES

Alberty R. A., Burmenko E., Kang T. H., and Chung M. B. (1987)Standard chemical thermodynamic properties of alkanethiol isomergroups. J. Phys. Chem. Ref. Data. 16, 193–208.

Antoine Ch. (1888). Tension des vapeurs: nouvelle relation entre lestensions et les temperatures. C. R. Acad. Sci. 107, 681–684.

von Auwers K. (1915) Spektrochemische Untersuchungen. JustusLiebig Annalen der Chemie 408, 212–284.

Benson S. W. (1976) Thermochemical Kinetics., 2nd Ed:Wiley.Berg W. T., Scott D. W., Hubbard W. N., Todd S. S., Messerly J. F.,

Hossenlopp I. A., Osborn A., Douslin D. R., and McCullough J. P.(1961) The chemical thermodynamic properties of cyclopentane-thiol. J. Phys. Chem. 65, 1425–1430.

Brassel S. C., Lewis C. A., de Leeuw J. W., de Lange F., and SinningheDamste J. S. (1986) Isoprenoid thiophenes: novel products of sedi-ment diagenesis? Nature 320, 160–162.

Brown O. L. I. and Manov G. G. (1937) The heat capacity of carbondisulfide from 15 to 300°K. The entropy and heat of fusion of carbondisulfide. J. Am. Chem. Soc. 59, 500–502.

Carlson H. G. and Westrum E. F., Jr. (1965) 2,5-Dimethylthiophene.Heat capacities and thermodynamic properties from 5 to 300°K. andfusion of stable and metastable phases. J. Phys. Chem. 69, 1524–1530.

Chakhmakhchev A., Suzuki M., and Takayama K. (1997) Distributionof alkylated dibenzothiophenes in petroleum as a tool for maturityassessments. Org. Geochem. 26, 483–490.

Chen J.-Z. and Jiang S.-C. (1980) Rapid determination of crystallinityin poly(p-phenylene sulfide) by x-ray diffraction method. Hua HsuehHsueh Pao 38, 50–56. (in Chinese).

Cheng S. Z. D., Wu Z. Q., and Wunderlich B. (1987) Glass transitionand melting behavior of poly(thio-1,4-phenylene). Macromolecules20, 2802–2810.

Chirico R. D., Knipmeyer S. E., Nguyen A., and Steele W. V. (1991a)The thermodynamic properties of benzo[b]thiophene. J. Chem. Ther-modyn. 23, 759–779.

Chirico R. D., Knipmeyer S. E., Nguyen A., and Steele W. V. (1991b)The thermodynamic properties of dibenzothiophene. J. Chem. Ther-modyn. 23, 431–450.

Coplen T. B. (1996) Atomic weights of the elements 1995. Pure Appl.Chem. 68, 2339–2359 (prepared for publication by).

Cox J. D., Wagman D. D., and Medvedev V. A. (1989) CODATA KeyValues for Thermodynamics. Hemisphere Publishing Corporation.

Table 12. Standard molal thermodynamic properties and heat capacity power function coefficients of liquid methylated dibenzo[b,d]thiophenes.



Dibenzo[b,d]thiophene C12H8S 59558 33155 60.50 152.5 59.07 40.85 83.6 �5.9641-Methyldibenzo[b,d]thiophene C13H10S 64618 29734 64.66 167.4 65.86 41.38 104.6 �5.9642- or 3-Methyldibenzo[b,d]thiophene C13H10S 57322 23556 68.41 169.5 65.51 43.75 95.5 �5.9644-Methyldibenzo[b,d]thiophene C13H10S 57220 23755 69.42 167.4 65.95 45.65 90.6 �5.9641,2-Dimethyldibenzo[b,d]thiophene C14H12S 63159 20912 72.57 185.1 74.62 42.19 124.3 �4.1121,3-, 1,7- or 1,8-Dimethyldibenzo[b,d]thiophene C14H12S 62382 20135 72.57 184.4 72.31 44.28 116.5 �5.9641,4- or 1,6-Dimethyldibenzo[b,d]thiophene C14H12S 62280 20334 73.58 182.3 72.74 46.18 111.6 �5.9642,3-Dimethyldibenzo[b,d]thiophene C14H12S 55863 14734 76.32 187.2 74.28 44.56 115.2 �4.1122,4-, 2,6-, 3,6- or 3,7-Dimethyldibenzo[b,d]thiophene C14H12S 54984 14156 77.33 184.4 72.40 48.55 102.5 �5.9642,7- or 2,8-Dimethyldibenzo[b,d]thiophene C14H12S 55086 13957 76.32 186.5 71.96 46.65 107.4 �5.9643,4-Dimethyldibenzo[b,d]thiophene C14H12S 55761 14933 77.33 185.1 74.72 46.46 110.3 �4.1124,6-Dimethyldibenzo[b,d]thiophene C14H12S 54882 14355 78.34 182.3 72.84 50.45 97.6 �5.964

a Cal mol�1 b Cal mol�1K�1 c Cm3mol�1 d Cal mol�1K�2 e Cal K mol�1 f Calculated from Eqn. 13 g Calculated from Eqn. 5

3870 L. Richard

Cunningham J. R. (1974) Calculation of Parameters From GroupContributions for the PFGC Equation of State. M. Sc. thesis,Brigham Young Univ.

Davies J. V. and Sunner S. (1962) Heats of combustion and formationof thiolane and of the thiolenes. Acta Chem. Scandin. 16, 1870–1876.

Davis H. G. and Gottlieb S. (1963) Density and refractive index ofmulti-ring aromatic compounds in the liquid state. Fuel 42, 37–54.

Dictionary of Organic Compounds (1982) 5th Edition (eds. J. Buck-ingham and S. M. Donaghy), Volume One. Chapman and Hall.

Domalski E. S. and Hearing E. D. (1993) Estimation of the thermody-namic properties of C-H-N-O-S-halogen compounds at 298.15 K. J.Phys. Chem. Ref. Data. 22, 805–1159.

Douslin D. R. and Huffman H. M. (1946) The heat capacities, heats oftransition, heats of fusion and entropies of cyclopentane, methylcy-clopentane and methylcyclohexane. J. Am. Chem. Soc. 68, 173–176.

Dreisbach R. R. (1955) Physical Properties of Chemical Compounds.Advances in Chemistry Series. 15, American Chemical Society.

Dreisbach R. R. (1961) Physical Properties of Chemical Compounds –III. Advances in Chemistry Series. 29, American Chemical Society.

Finke H. L., Gross M. E., Messerly J. F., and Waddington G. (1954)Benzothiophene: Heat capacity, heat of transition, heat of fusion andentropy. An order-disorder transition. J. Am. Chem. Soc. 76, 854–857.

Girelli A. (1953) Relazioni proprieta-struttura in composti solforatiorganici. La Ricerca Scientifica. 23, 1988–1991.

Good W. D. (1972) Enthalpies of combustion of 18 organic sulfurcompounds related to petroleum. J. Chem. Eng. Data. 17, 158–162.

Good W. D. and Smith N. K. (1969) Enthalpies of combustion oftoluene, benzene, cyclohexane, cyclohexene, methylcyclopentane,1-methylcyclopentene, and n-hexane. J. Chem. Eng. Data. 14, 102–106.

Good W. D., Lacina J. L., and McCullough J. P. (1961) Methanethioland carbon disulfide: Heats of combustion and formation by rotating-bomb calorimetry. J. Phys. Chem. 65, 2229–2231.

Gransch J. A. and Posthuma J. (1974) On the origin of sulphur incrudes. In Advances in Organic Geochemistry 1973 (eds. B. Tissotand F. Bienner), pp. 727–739. Editions Technip.

Gross M. E., Oliver G. D., and Huffman H. M. (1953) Low-tempera-ture thermal data for some C7H14 alkylcyclopentanes. J. Am. Chem.Soc. 75, 2801–2804.

Guthrie G. B. Jr, Scott D. W., and Waddington G. (1952) Thiacyclo-propane (ethylene sulfide): Infrared spectrum, vapor pressure andsome thermodynamic properties. J. Am. Chem. Soc. 74, 2795–2800.

Haar L., Gallagher J. S., and Kell G. S. (1984) NBS/NRC Steam Tables.Thermodynamic and Transport Properties and Computer Programsfor Vapor and Liquid States of Water in SI Units. HemispherePublishing Corporation.

Haines W. E., Helm R. V., Cook G. L., and Ball J. S. (1956) Purifi-cation and properties of ten organic sulfur compounds — secondseries. J. Phys. Chem. 60, 549–555.

Handbook of Chemistry and Physics (1992) 73rd Edition (ed. D. R.Lide). CRC Press.

Handbook of Data on Organic Compounds (1989) 2nd Edition (eds.R. C. Weast and J. G. Grasselli), Volume II. CRC Press.

Helgeson H. C., Delany J. M., Nesbitt H. W., and Bird D. K. (1978)Summary and critique of the thermodynamic properties of rock-forming minerals. Am. J. Sci. 278-A, 1–229.

Helgeson H. C., Owens C. E., Knox A. M., and Richard L. (1998)Calculation of the standard molal thermodynamic properties of crys-talline, liquid, and gas organic molecules at high temperatures andpressures. Geochim. Cosmochim. Acta 62, 985–1081.

Hossenlopp I. A. and Scott D. W. (1981) Vapor heat capacities andenthalpies of vaporization of six organic compounds. J. Chem.Thermodyn. 13, 405–414.

Hubbard W. N. and Waddington G. (1954) The heats of combustion,formation and isomerization of propanethiol-1, propanethiol-2 and2-thiabutane. Rec. Trav. Chim. 73, 910–923.

Hubbard W. N., Finke H. L., Scott D. W., McCullough J. P., Katz C.,Gross M. E., Messerly J. F., Pennington R. E., and Waddington G.(1952) Thiacyclopentane: Heat capacity, heats of fusion and vapor-ization, vapor pressure, entropy, heat of formation and thermody-namic functions. J. Am. Chem. Soc. 74, 6025–6030.

Hubbard W. N., Katz C., and Waddington G. (1954) A rotating com-bustion bomb for precision calorimetry. Heats of combustion ofsome sulfur-containing compounds. J. Phys. Chem. 58, 142–152.

Hubbard W. N., Good W. D., and Waddington G. (1958a) The heats ofcombustion, formation and isomerization of the seven isomericC4H10S alkane thiols and sulfides. J. Phys. Chem. 62, 614–617.

Hubbard W. N., Douslin D. R., McCullough J. P., Scott D. W., ToddS. S., Messerly J. F., Hossenlopp I. A., George A., and WaddingtonG. (1958b) 2,3-Dithiabutane, 3,4-dithiahexane and 4,5-dithiaoctane:Chemical thermodynamic properties from 0 to 1000°K. J. Am.Chem. Soc. 80, 3547–3554.

Huffman H. M., Todd S. S., and Oliver G. D. (1949) Low temperaturethermal data on eight C8H16 alkylcyclohexanes. J. Am. Chem. Soc.71, 584–592.

Immirzi A. and Perini B. (1977) Prediction of density in organiccrystals. Acta Cryst. A33, 216–218.

Ivlev A. A., Pankina R. G., and Gal’peri G. D. (1973) Thermodynamicsof reactions of sulfurization of oil. Petrol. Geol. 11, 70–75.

Johnson W. H., Prosen E. J., and Rossini F. D. (1946) Heats ofcombustion of four cyclopentane and five cyclohexane hydrocar-bons. J. Res. Natl. Bur. Standards 36, 463–468.

Johnson W. H., Prosen E. J., and Rossini F. D. (1947) Heats ofcombustion and isomerization of the eight C8H16 alkylcyclohexanes.J. Res. Natl. Bur. Standards 39, 49–52.

Johnson W. H., Prosen E. J., and Rossini, F. D. (1949) Heats ofcombustion and isomerization of the six C7H14 alkylcyclopentanes.J. Res. Natl. Bur. Standards 42, 251–255.

Kjær A. (1977) Low molecular weight sulphur-containing compoundsin nature: a survey. Pure Appl. Chem. 49, 137–152.

Krein E. B. (1993) Organic sulfur in the geosphere: analysis, structuresand chemical processes. In Supplement S: The Chemistry of Sulphur-containing Functional Groups (eds. S. Patai and Z. Rappoport), pp.975–1032. Wiley.

Larson S. B., Simonsen S. H., Martin G. E., Smith K., and Puig-TorresS. (1984) Structures of thianthrene (I), C12H8S2, (redeterminations at163 K and 295 K) and 1-azathianthrene (II), C11H7NS2, (at 163 K).Acta Cryst. C40, 103–106.

Mackle H. and Mayrick R. G. (1962) Studies in the thermochemistry oforganic sulphides. Part 2. - The gas-phase heats of formation of tenaliphatic sulphides. Trans. Farad. Soc. 8, 230–237.

Mackle H. and McClean R. T. B. (1964) Studies in the thermochem-istry of organic sulphides. Part 5. - Dithia-alkanes. Trans. Farad.Soc. 10, 669–672.

Maier C. G. and Kelley K. K. (1932) An equation for the representationof high temperature heat-content data. J. Am. Chem Soc. 54, 3243–3246.

Majeed A. I. and Wagner J. (1986) Parameters from group contribu-tions equation and phase equilibria in light hydrocarbon systems. InEquations of State: Theories and Applications (eds. K. C. Chao andR. L. Robinson Jr.), pp. 452–473. ACS.

Majer V. and Svoboda V. (1985) Enthalpies of Vaporization of Or-ganic Compounds. Blackwell.

McCullough J. P., Scott D. W., Finke H. L., Hubbard W. N., GrossM. E., Katz C., Pennington R. E., Messerly J. F., and Waddington G.(1953a) The thermodynamic properties of 2-methyl-2-propanethiolfrom 0 to 1000°K. J. Am. Chem. Soc. 75 1818–1824.

McCullough J. P., Sunner S., Finke H. L., Hubbard W. N., Gross M. E.,Pennington R. E., Messerly J. F., Good W. D., and Waddington G.(1953b) The chemical thermodynamic properties of 3-methylthio-phene from 0 to 1000°K: J. Am. Chem. Soc. 75, 5075–5081.

McCullough J. P., Finke H. L., Scott D. W., Gross M. E., MesserlyJ. F., Pennington R. E., and Waddington G. (1954a) 2-Propanethiol:Experimental thermodynamic studies from 12 to 500°K. The chem-ical thermodynamic properties from 0 to 1000°K. J. Am. Chem. Soc.76, 4796–4802.

McCullough J. P., Finke H. L., Hubbard W. N., Good W. D., Penning-ton R. E., Messerly J. F., and Waddington G. (1954b) The chemicalthermodynamic properties of thiacyclohexane from 0 to 1000°K.J. Am. Chem. Soc. 76, 2661–2669.

McCullough J. P., Finke H. L., Messerly J. F., Pennington R. E.,Hossenlopp I. A., and Waddington G. (1955) 3-Methyl-2-thiabutane:Calorimetric studies from 12 to 500°K.; the chemical thermody-


namic properties from 0 to 1000°K. J. Am. Chem. Soc. 77, 6119–6125.

McCullough J. P., Hubbard W. N., Frow F. R., Hossenlopp I. A., andWaddington G. (1957) Ethanethiol and 2-thiapropane: Heats offormation and isomerization; The chemical thermodynamic proper-ties from 0 to 1000°K. J. Am. Chem. Soc. 79, 561–566.

McCullough J. P., Finke H. L., Scott D. W., Pennington R. E., GrossM. E., Messerly J. F., and Waddington G. (1958) 2-Butanethiol:Chemical thermodynamic properties between 0 and 1000°K.; Rota-tional conformations. J. Am. Chem. Soc. 80, 4786–4793.

McCullough J. P., Finke H. L., Hubbard W. N., Todd S. S., MesserlyJ. F., Douslin D. R., and Waddington G. (1961) Thermodynamicproperties of four linear thiaalkanes. J. Phys. Chem. 65, 784–791.

Messerly J. F., Todd S. S., and Guthrie G. B., Jr. (1967) Low-temperature thermal properties of cyclohexanethiol and 2,4-dimeth-yl-3-thiapentane. J. Chem. Eng. Data. 12, 426–429.

Messerly J. F., Finke H. L., and Todd S. S. (1974) Low-temperaturethermal studies on six organo-sulfur compounds. J. Chem. Thermo-dyn. 6, 635–657.

Morris J. C., Lanum W. J., Helm R. V., Haines W. E., Cook G. L., andBall J. S. (1960) Purification and properties of ten organic sulfurcompounds. J. Chem. Eng. Data. 5, 112–116.

O’Brien L. J. and Alford W. J. (1951) Thermodynamic properties ofcarbon disulfide. Ind. Eng. Chem. 43, 506–510.

Orr W. L. (1986) Kerogen/asphaltene/sulfur relationships in sulfur-richMonterey oils. Org. Geochem. 10, 499–516.

Orr W. L. and Sinninghe Damste J. S. (1990) Geochemistry of sulfurin petroleum systems. In Geochemistry of Sulfur in Fossil Fuels (eds.W.L. Orr and C.M. White), ACS Symp. Ser. 429, 2–29, AmericanChemical Society.

Osborn A. G. and Douslin D. R. (1966) Vapor pressure relations of 36sulfur compounds present in petroleum. J. Chem. Eng. Data. 11,502–509.

Osborn A. G. and Scott D. W. (1980) Vapor pressures of 17 miscel-laneous organic compounds. J. Chem. Thermodyn. 12, 429–438.

Osborne D. W., Doescher R. N., and Yost D. M. (1942) The heatcapacity, heats of fusion and vaporization, vapor pressure and en-tropy of dimethyl sulfide. J. Am. Chem. Soc. 64, 169–172.

Payzant J. D., Montgomery D. S., and Strausz O. P. (1983) Novelterpenoid sulfoxides and sulfides in petroleum. Tetrahedron Lett. 24,651–654.

Payzant J. D., Montgomery D. S., and Strausz O. P. (1986) Sulfides inpetroleum. Org. Geochem. 9, 357–369.

Pennington R. E., Finke H. L., Hubbard W. N., Messerly J. F., FrowF. R., Hossenlopp I. A., and Waddington G. (1956) The chemicalthermodynamic properties of 2-methylthiophene. J. Am. Chem. Soc.78, 2055–2060.

Radke M. and Willsch H. (1994) Extractable alkyldibenzothiophenes inPosidonia Shale (Toarcian) source rocks: Relationship of yields topetroleum formation and expulsion. Geochim. Cosmochim. Acta 58,5223–5244.

Rall H. T., Thompson C. J., Coleman H. J., and Hopkins R. L. (1972)Sulfur compounds in crude oil. U.S. Bur. Mines Bull. 659, 187 p.

Richard L. and Helgeson H. C. (1998) Calculation of the thermody-namic properties at elevated temperatures and pressures of saturatedand aromatic high molecular weight solid and liquid hydrocarbons inkerogen, bitumen, petroleum, and other organic matter of biogeo-chemical interest. Geochim. Cosmochim. Acta 62, 3591–3636.

Richard L. and Helgeson H. C. (2001). Calculation of the standardmolal volumes of crystalline and liquid organic compounds as afunction of temperature and pressure. Geochim. Cosmochim. Acta

Richnow H. H., Jenisch A., and Michaelis W. (1992) Structural inves-tigations of sulphur-rich macromolecular oil fractions and a kerogenby sequential chemical degradation. Org. Geochem. 19, 351–370.

Ruehrwein R. A. and Huffman H. M. (1943) Thermal data. XVII. Theheat capacity, entropy, and free energy of formation of cyclohexane.A new method of heat transfer in low temperature calorimetry.J. Am. Chem. Soc. 65, 1620–1625.

Schmid J.-C., Connan J., and Albrecht P. (1987) Occurrence andgeochemical significance of long-chain dialkylthiacyclopentanes.Nature 329, 54–56.

Scott D. W. and Crowder G. A. (1967) Cyclohexanethiol and 2,4-dimethyl-3-thiapentane: Molecular vibrations, conformational anal-

yses, and chemical thermodynamic properties. J. Chem. Phys. 46,1054–1062.

Scott D. W., Finke H. L., Gross M. E., Guthrie G. B., and HuffmanH. M. (1950) 2,3-Dithiabutane: Low temperature heat capacity, heatof fusion, heat of vaporization, vapor pressure, entropy and thermo-dynamic functions. J. Am. Chem. Soc. 72, 2424–2430.

Scott D. W., Finke H. L., McCullough J. P., Gross M. E., WilliamsonK. D., Waddington G., and Huffman H. M. (1951) Thermodynamicproperties and rotational isomerism of 2-thiabutane. J. Am. Chem.Soc. 73, 261–265.

Scott D. W., Finke H. L., Hubbard W. N., McCullough J. P., OliverG. D., Gross M. E., Katz C., Williamson K. D., Waddington G., andHuffman H. M. (1952a) 3-Thiapentane: Heat capacity, heats offusion and vaporization, vapor pressure, entropy, heat of formationand thermodynamic functions. J. Am. Chem. Soc. 74, 4656–4662.

Scott D. W., Finke H. L., McCullough J. P., Gross M. E., PenningtonR. E., and Waddington G. (1952b) 3,4-Dithiahexane: Heat capacity,heats of fusion and vaporization, vapor pressure, entropy, and ther-modynamic functions. J. Am. Chem. Soc. 74, 2478–2483.

Scott D. W., Finke H. L., Hubbard W. N., McCullough J. P., Katz C.,Gross M. E., Messerly J. F., Pennington R. E., and Waddington G.(1953) Thiacyclobutane: Heat capacity, heats of transition, fusionand vaporization, vapor pressure, entropy, heat of formation andthermodynamic functions. J. Am. Chem. Soc. 75, 2795–2800.

Scott D. W., McCullough J. P., Hubbard W. N., Messerly J. F.,Hossenlopp I. A., Frow F. R., and Waddington G. (1956) Benzene-thiol: Thermodynamic properties in the solid, liquid and vapor states;internal rotation of the thiol group. J. Am. Chem. Soc. 78, 5463–5468.

Scott D. W., Finke H. L., McCullough J. P., Messerly J. F., PenningtonR. E., Hossenlopp I. A., and Waddington G. (1957) 1-Butanethioland 2-thiapentane. Experimental thermodynamic studies between 12and 500°K.; Thermodynamic functions by a refined method ofincrements. J. Am. Chem. Soc. 79, 1062–1068.

Scott D. W., McCullough J. P., Messerly J. F., Pennington R. E.,Hossenlopp I. A., Finke H. L., and Waddington G. (1958) 2-Methyl-1-propanethiol: Chemical thermodynamic properties and rotationalisomerism. J. Am. Chem. Soc. 80, 55–59.

Scott D. W., Douslin D. R., Finke H. L., Hubbard W. N., Messerly J. F.,Hossenlopp I. A., and McCullough J. P. (1962a) 2-Methyl-2-buta-nethiol: Chemical thermodynamic properties and rotational isomer-ism. J. Phys. Chem. 66, 1334–1341.

Scott D. W., Good W. D., Todd S. S., Messerly J. F., Berg. W. T.,Hossenlopp I. A., Lacina J. L., Osborn A., and McCullough J. P.(1962b) 3,3-Dimethyl-2-thiabutane: Chemical thermodynamic prop-erties and barriers to internal rotation. J. Chem. Phys. 36, 406–412.

Sinninghe Damste J. S. and de Leeuw J. W. (1987) The origin and fateof isoprenoid C20 and C15 sulphur compounds in sediments and oils.Intern. J. Environ. Anal. Chem. 28, 1–19.

Sinninghe Damste J. S. and de Leeuw J. W. (1990) Analysis, structureand geochemical significance of organically-bound sulphur in thegeosphere: State of the art and future research. Org. Geochem. 16,1077–1101.

Sinninghe Damste J. S., ten Haven H. L., de Leeuw J. W., and SchenckP. A. (1986) Organic geochemical studies of a Messinian evaporiticbasin, northern Apennines (Italy) —II. Isoprenoid and n-alkyl thio-phenes and thiolanes. Org. Geochem. 10, 791–805.

Sinninghe Damste J. S., de Leeuw J. W.,. Kock-van Dalen A. C., deZeeuw M. A., de Lange F., Ripstra W. I. C., and Schenck P. A.(1987) The occurrence and identification of series of organic sulphurcompounds in oils and sediments extracts. I. A study of the RozelPoint Oil (U.S.A.). Geochim. Cosmochim. Acta 51, 2369–2391.

Sinninghe Damste J. S., Ripstra W. I. C.,. Kock-van Dalen A. C., deLeeuw J. W., and Schenck P. A. (1989a) Quenching of labilefunctionalised lipids by inorganic sulphur species: Evidence for theformation of sedimentary organic sulphur compounds at the earlystages of diagenesis. Geochim. Cosmochim. Acta 53, 1343–1355.

Sinninghe Damste J. S., Ripstra W. I. C., de Leeuw J. W., and SchenckP. A. (1989b) The occurrence and identification of series of organicsulphur compounds in oils and sediment extracts: II. Their presencein samples from hypersaline and non-hypersaline palaeoenviron-ments and possible application as source, palaeoenvironmental andmaturity indicators. Geochim. Cosmochim. Acta 53, 1323–1341.

3872 L. Richard

Smirnova N. N., Lebedev B. V., and Wunderlich B. (1996) Heatcapacity and thermodynamic functions of poly(thio-1,4-phenylene),poly(oxy-1,4-benzoyl), and poly(oxy-2,6-dimethyl-1,4-phenylene)at 0–325 K. Vysokomol. Soedin. Seriya A 38, 210–215. (in Russian).

Steele W. V., Chirico R. D., Knipmeyer S. E., and Nguyen A. (1993)The thermodynamic properties of thianthrene and phenoxathiin.J. Chem. Thermodyn. 25, 965–992.

Steele W. V., Chirico R. D., Cowell A. B., Nguyen A., and KnipmeyerS. E. (1995) Possible precursors and products of deep hydrodesul-furization of distillate fuels. I. The thermodynamic properties ofdiphenylsulfide and densities and revised properties for dibenzothio-phene. J. Chem. Thermodyn. 27, 1407–1428.

Stull D. R., Westrum E. F., Jr, and Sinke G. S. (1969) The ChemicalThermodynamic Properties of Organic Compounds. John Wiley &Sons Incorporated.

Sunner S. (1949) Studies in combustion calorimetry applied to organo-sulphur compounds. Ph.D. Dissertation, Univ. Lund.

Sunner S. (1955) Thermochemical investigations on organic sulfurcompounds. V. On the resonance energy of thiolacetic acid, thiourea,thiosemicarbazide, thiophene and thianthrene. Acta Chem. Scandin.9, 847–854.

Sunner S. (1963) Corrected heat of combustion and formation valuesfor a number of organic sulphur compounds. Acta Chem. Scandin.17, 728–730.

Tissot B. P. and Welte D. H. (1984) Petroleum Formation and Occur-rence, 2nd Edition: Springer.

TRC Thermodynamic Tables (1986) Hydrocarbons. (eds. K.L. Aljoe etal.) Thermodynamics Research Center. Texas A & M University.

Vaidya S. N. and Kennedy G. C. (1971) Compressibility of 18 molec-ular organic solids to 45 kbar. J. Chem. Phys. 55, 987–992.

Vairavamurthy A. and Mopper K. (1987) Geochemical formation oforganosulphur compounds (thiols) by addition of H2S to sedimentaryorganic matter. Nature 329, 623–625.

Valisolalao J., Perakis N., Chappe B., and Albrecht P. (1984) A novelsulfur containing C35 hopanoid in sediments. Tetrahedron Lett. 25,1183–1186.

van Kaam-Peters H. M. E., Koster J., de Leeuw J. W., SinningheDamste J. S. (1995) Occurrence of two novel benzothiophene ho-panoid families in sediments. Org. Geochem. 23, 607–616.

Waddington G., Knowlton J. W., Scott D. W., Oliver G. D., Todd S. S.,Hubbard W. N., Smith J. C., and Huffman H. M. (1949) Thermo-dynamic properties of thiophene. J. Am. Chem. Soc. 71, 797–808.

Waddington G., Smith J. C., Williamson K. D., and Scott D. W. (1962)Carbon disulfide as a reference substance for vapor-flow calorimetry;The chemical thermodynamic properties. J. Phys. Chem. 66, 1074–1077.

Wagman D. D., Evans W. H., Parker V. B., Schumm R. H., Halow I.,Bailey S. M., Churney K. L., and Nuttall R. L. (1982) The NBStables of chemical thermodynamic properties: Selected values forinorganic and C1 and C2 organic substances in SI units. J. Phys.Chem. Ref. Data. 11, Supplement 2, 392 p.

White P. T., Barnard-Smith D. G., and Fidler F. A. (1952) Vaporpressure - temperature relationships of sulfur compounds related topetroleum. Ind. Eng. Chem. 44, 1430–1438.

Zabransky M., Ruzicka V. Jr, Majer V., and Domalski E. S. (1996)Heat capacity of liquids – Volumes I and II – Critical Review andRecommended Values. J. Phys. Chem. Ref. Data Monograph 6.


APPENDIX 1-IDEALIZED STRUCTURAL REPRESENTATION OF ORGANIC SULFUR COMPOUNDS CONSIDERED IN THEPRESENT STUDY

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APPENDIX 2 - POSITIONAL NUMBERING CONVENTIONS


calculation of the standard molal thermodynamic properties as a function of temperature and...

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