Purification of Inorganic and Metal-Organic Chemicals 367

Arsenic triiodide [50288-23-81 M 455.6, m 146O. Crystd from acetone.

Arsenic I11 oxide [1327-53-31 M 197.8. Crystd from dil HCl (1:2), washed, dried and sublimed. Analytical reagent grade material is suitable for use as an analytical standard after it has been dried by heating at 105O for 1-2h or has been left in a desiccator for several hours over conc H2SO4.

3-(2-Arsenophenylazo)-4,5-dihydroxynaphthalene-2,7-disulphonic acid (trisodium salt) see Arsenazo.

Aurothioglucose (gold thioglucose) [ I 2 1 92-57-31 M 139.2. Purified by dissolving in H20 (0.05g in lml) and ppting by adding EtOH. Yellow cryst with slight mercaptan odour. Decomposes slowly in H20, sol in propylene glycol but insol in EtOH and other common organic solvents. [FEES LE'IT 98 351 19701.

Barium (metal) [7440-39-31 M 137.3. Cleaned by washing with ethyl ether to remove adhering paraffin, then filed in an argon-filled glove box, washed first with ethanol containing 2% conc HCI, then with dry ethanol. Dried under vacuum and stored under argon [Addison, Coldrey and Halstead JCS 3868 19621. Has also been purified by double distn under lOmm argon pressure.

Barium acetate [543-80-61 M 255.4. Crystd twice from anhydrous acetic acid and dried under vacuum for 24h at looo.

Barium bromate [13967-90-31 M 265.3. Crystd from hot water (20mVg).

Barium bromide (2H20) [7791-28-81 M 333.2. Crystd from water (lml/g) by partial evaporation in a desiccator.

Barium chlorate (HzO) [13477-00-41 M 322.3. Crystd from water (1mVg) between looo and Oo

Barium chloride (2H20) [10326-27-91 M 244.3. Twice crystd from water (2ml/g) and oven dried to constant weight.

Barium dithionate (2H20) [ I38451 7-51 M 333.5. Crystd from water.

Barium ferrocyanide (6H2O) [13821-06-2] M 594.8. Crystd from hot water (100mUg).

Barium fluoride [7787-32-81 M 175.3, m 1353O, b 2260°, d 4.83. Washed well with distd H20 and dried in vacuum Sol in H20 [ 1.6g (loo), 1.6g (20O) and 1 .62g(3Oo) per L), mineral acids and aq NH4Cl. May be stored in glass bottles. [Handbook of Preparative Inorganic Chemistry (ed Erauer) Vol I 234 19631.

Barium formate [541-43-51 M 277.4. Crystd from warm water (4ml/g) by adding EtOH and cooling.

Barium hydroxide (8H2O) [12230-71-61 M 315.5, m 78O. Crystd from water (lml/g).

Barium hypophosphite (H20) [14871-79-51 M 285.4. Ppted from aq soln (3ml/g) by adding EtOH.

Barium iodate (H20) [10567-69-81 M 505.2. Crystd from a large volume of hot water by cooling.

Barium iodide (2H20) [7787-33-91 M 427.2. Crystd from water (0.5ml/g) by partial evapn in a desiccator

Barium ionophore I [N,N,N',N'-tetracyclohexyloxy-bis-(o-phenyleneoxy)diacetamide] [96476-01-61 M 644.9, m 156-158O. Purified by chromatography on a Kieselgel column and eluted with

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368 Purification of Inorganic and Metal-Organic Chemicals

CH2Cl2-EtOAc (5: 1), and recryst from EtOH-Me2CO as colourless crystals. It is an electrically neutral ionophore with high selectivity for Ba++ions and with high lipophilicity. [ B 118 1071 19851.

Barium manganate [7787-35-11 M 256.3. Wash with conductivity H 2 0 by decantation until the supernatant gives a faint test for Ba++. Remove excess H20 in vac (IMPORTANT), then heat at 100° and the last traces of H20 are removed in a vac desiccator over P2O5. Store over KOH. It disproportionates in hot H20 or dil acid to Ba(MnO2)2 and MnO2, and is a mild oxidant. [JAG'S 44 1965 1924; lnorg Synfh 11 56 19601.

Barium nitrate overnight at 1 1 Oo.

[10022-31-81 M 261.4, m 593O(dec). Crystd twice from water (4ml/g) and dried

Barium nitrite (H20) [7787-38-41 M 247.4. Crystd from water (lml/g) by cooling in an ice-salt bath.

Barium perchlorate [13465-95-71 M 336.2, m 5 0 5 O . Crystd twice from water.

Barium propionate (H2O) [5908-77-01 M 301.5. Crystd from warm water (50ml/g) by adding EtOH and cooling.

Barium sulphate [7722-43- 71 M 233.4. Washed five times by decantation with hot distilled water, dialysed against distd water for one week, then freeze-dried and oven dried at 105O for 12h.

Barium tetrathionate [82203-66-51 M 361.6. Purified by dissolution in a small volume of water and ppted with EtOH below 5 O . After drying the salt was stored in the dark at Oo.

Barium thiocyanate (2 H20) [2092-17-31 M 289.6. Crystd from water (2.5ml/g) by partial evaporation in a desiccator.

Barium thiosulphate [35112-53-91 M 249.5. Very slightly soluble in water. Washed repeatedly with chilled water and dried in air at 40°.

Benzenearsonic acid see Phenylarsonic acid.

Benzenechromium tricarbonyl [12082-08-51 M 214.1. m 163-166O. Purified by sublimation in vacuo.

Benzenephosphinic acid [ I 779-48-21 M 142.1, m ca 70°. Purified by allowing to stand for several days under ethyl ether, with intermittent shaking and several changes of solvent. After filtration, the excess ether was removed in vacuum.

Benzeneseleninic acid [6996-92-51 M 189.1, m 123-124O. Recrystd twice from water [Kice and Purkiss JOC 52 3448 19871.

Benzenestibonic acid (535-46-61 M 248.9, m >250°(dec). Crystd from acetic acid, or from EtOH- CHC13 mixture by addition of water.

Benzyltriphenylphosphonium chloride [ 11 00-88-51 M 388.9, m 280° (sintering), 287-288O. Wash with Et2O and crystallise from EtOH (six sided plates). Hygroscopic and forms crystals with one mol HzO. [A 229 320 1885; B 83 291 19501.

Beryllium acetate (basic) [543-81-71 M 406.3, m 285-286O. Crystd from chloroform.

Beryllium potassium fluoride [7787-50-01 M 105.1. Crystd from hot water (25ml/g).

Beryllium sulphate (4H20) [7787-56-61 M 177.1. Crystd from weak aqueous H2SO4.

Purification of Inorganic and Metal-Organic Chemicals 369

Bicyclo[2.2.l]hepta-2,5-diene rhodium (I) chloride dimer (norbornadiene rhodium chloride complex dimer) [12257-42-01 M 462, m 240°(dec). Recrystd from hot CHCl3-pet ether as fine crystals soluble in CHC13 and C6H6 but almost insoluble in Et20 or pet ether. [JCS 3178 19591.

2-Biphenylyl diphenyl phosphate [132-29-6 J M 302.4, n251.5925. Vacuum distd, then percolated through an alumina column. Passed through a packed column maintained at 150° to remove residual traces of volatile materials by a counter-current stream of nitrogen at reduced pressure. [Dobry and Keller JPC 61 1448 19571.

2,2'-Bipyridineruthenous dichloride (6H2O), see tris(2,2'-bipyridine)ruthenous dichloride.

2,2'-Bipyridinium chlorochromate [ 76899-34-81 M 292.6. Washed with cold conc HCl then H20 (sintered glass funnel) and dried in vacuum (CaC12) to a free flowing yellow-brown powder. Stored in the dark. [S 691 1980; SC 10 951 1980).

Bis-(p-tert-buty1phenyl)phenyl Same as for 2-biphenylyl diphenyl phosphate (above).

phosphate [I 15-87-71 M 438.5, b 281°/5mm, n25 1.5412.

Bis-(2-chlorophenyl) phenyl phosphate [597-80-81 M 395, b 254O/4mm, n25 1.5767. Same as for 2-biphenylyl diphenyl phosphate above.

Bis(2,9-dimethyl-l,lO-phenanthroline) copper(1) perchlorate [54816-44-51 M 579.6. Crystd from acetone.

1,l'-Bis-(dipheny1phosphino)ferrocene [12150-46-81 M 554.4, m 181-183O, 184-194O. Wash with distilled H20 and dry in a vacuum. Dissolve in ca 5 parts of hot dioxane and cool to give orange crystals m 18 1 - 183O. Recrystn from CgHg-heptane ( 1 :2) gives product with m 183- 184O. [J Organometal Chem 27 241 19711.

Bis-(2-ethylhexyl) 2-ethylhexyl phosphonate [25103-23-5 J M 434.6, n25 1.4473. Purified by stirring an 0.4M soln in benzene with an equal volume of 6M HCl at ca 60° for 8h. The benzene layer was then shaken successively with equal volumes of water (twice), aqueous 5% NaZC03 (three times), and water (eight times), followed by evaporation of the benzene and dissolved water under reduced pressure at room temperature (using a rotating evacuated flask). Stored in dry, dark conditions [Peppard et al. J Znorg Nuclear Chem 24 1387 19621. Vacuum distilled, then percolated through an alumina column before finally passed through a packed column maintained at 150° where residual traces of volatile materials were removed by a counter-current stream of N2 at reduced pressure [Dobry and Keller JPC 61 1448 19571.

Bis-(2-ethylhexyl) phosphoric acid [298-07- 71 M 322.4, b 209°/10mm, d 0.965. See preceding entry and Peppard, Ferraro and Mason [J lnorg Nuclear Chem 7 231 19581 or Stewart and Crandall [JACS 73 1377 19511.

Bis(ethyl)titanium(IV) chloride [2247-00-91 M 177.0, Bis(ethyl)zirconium(IV) chloride [92212- 70-91 M 220.3. Crystd from boiling toluene.

2,4-Bis-( methylthi0)- 1 ,3,2h5 ,4h5-dithiadiphosphetane-2,4-dithione (Davy's reagent) [82737-61-91 M 284.4, m lao. Recrystd from C & j in yellow plates or from hot trichlorobenzene. The low m observed in the literature (112O with gradual softening at 68-102O) has been attributed to the presence of elemental sulphur in the crystals. [TET 40 2663 1984; JOC 22 789 1957.

Bismuth through dry Pyrex wool to remove any bismuth oxide present [Mayer, Yosim and Topol JPC 64 238 19601.

[7440-69-91 M 209.0, m 271-273O. Melted in an atmosphere of dry helium and filtered

Bismuthiol I, potassium salt [4628-94-8 J M 226.4, m 275-276O(dec). disulphide. Purified by crystn from EtOH.

Usually contaminated with

3 7 0 Purification of Inorganic and Metal-Organic Chemicals

Bismuth trichloride [7787-60-21 M 315.3, m 233.6O. Sublimed under high vacuum, or dried under a current of HCl gas, followed by fractional distn, once under HCl and once under argon.

Bismuth triphenyl (triphenyl bismuth) [603-33-81 M 440.3, m 75-76O, 77-78O, 78S0, d z8*' 1.6427(melt). Dissolve in EtOH, ppte with H20, extract with Et20, dry and evaporate when the residue crystallises. It has been recrystd from EtOH and Et20-EtOH and is a stable compound. [JCS supplement p121 1949; B 37 4620 1904; JACS 62 665 1940; UV: JCP 22 1430 19541.

Bis-(tetrabutylammonium) dichromate [56660-19-61 M 700.9, m 139-142O. Wash with water and dry in a vacuum. Crystallises from hexane (m 79-goo). [SC 10 75 19801.

Bis-[4-(1,1,3,3-tetramethylbutyl)phenyl]phosphate calcium salt (Selectophore) [40835-97-01 M 987.3. The Ca diester salt is washed with H20 (x3) and MeOH (x3) alternately and dried in a vacuum oven at 50". If the Ca salt is contaminated with much Ca salt of the monoester then it (log) is converted to the free acid by adding 6N HCl (ca IOvols) and Et20 (> 50vols) to it and stirred vigorously to form the free acids. When no white ppte remained (ca Smin), the Et20 is separated, washed with H20 (2 x > 50 ml) and dried by filtering through a bed of anhydrous Na2S04 (1 1 x 5 cm) which is then washed with Et2O (2 x >50 ml). Evapn gives an oil (TLC RF 0.81 for diester and 0.50 for monoester). The oil is dissolved in benzene (ca 25ml) and extracted with ethane-1,2-diol (25m1, lox). After ten washings, a small sample of the benzene layer is washed twice with H20 to remove the diol and showed that it is pure bis-[4-(1,1,3,3-tetramethylbuty1)- pheny1)phosphoric acid by TLC, i.e. no monophosphate. To form the Ca salt the oil is dissolved in MeOH and to it is added the equivalent amount of CaCI2 together with aq NaOH to keep the pH >lo. The resulting white ppte is collected washed alternately with 3 batches of H20 and MeOH and dried in a vacuum oven at 50". [JINC 40 1483 19781.

2,4-Bis-(p-tolylthio)-1,3,2h5,4.hs-dithiadiphosphetane-2,4-dithione (Heimgartner's reagent) [I 14234-09-21 M 436.6, m 175-176O. Recrystallise from toluene(1ight yellow solid), wash with Et20 and dry in a vacuum. [HCA 70 1001 19871.

Bis-(trimethylsily1)acetylene [14630-40- 11 M 170.4, m 26", b 134-136"/atm. Dissolve in pet ether, wash with ice-cold dilute HCl. The pet ether extract is dried (MgS04), evaporated and fractionated at atmospheric pressure. [JOMC 37 45 19721.

Bis-trimethylsilyl sulphide see hexamethyldisilthiane.

Bis-(triphenylphosphine)nickel(II) chloride [14264-16-51 M 654.2. Wash with glacial AcOH and dry in a vacuum over H2S04 and KOH until AcOH is completely removed. [JCS 719 19583.

Borax, see sodium borate.

Boric acid [10043-35-31 M 61.8. Crystd three times from H20 (3ml/g) between 100° and Oo, after filtering through sintered glass. Dried to constant weight over metaboric acid in a desiccator. (pKa25 9.23 in H20).

9-Borabicyclo[3.3.1]nonane (9BBN) [monomer 280-64-81 [d imer 70658-61-61 [I:I in te trahydrofuran 74422-63-41 M 122.0 (monomer), 244.0(dimer), m 141-143O, 150-152O, 154-155O; b 195°/12mm. Available as the solid dimer or in tetrahydrofuran soln. The solid is relatively stable and can be purified by distn in a vacuum (as dimer) and by recrystn from tetrahydrofuran (solubility at room temp is 9.5%, 0.78M), filter solid under N2 wash with dry pentane and dry in vacua at ca 100". The solid is a dimer (IR 1567cm-'), stable in air (for ca 2 months), and can be heated for 24h at 200° in an inert atmosphere without loss of hydride activity. It is a dimer in tetrahydrofuran soln also (IR 1567cm-l). It is sensitive to H20 and air (02) in soln. Concentration in soln can be determined by reaction with MeOH and measuring the vol of H2 liberated, or it can be oxidised to cis-cyclooctane-1.5-diol (m 73.5-74.5O). [IR: JACS 90 5280 1968, 96 7765 1974; JOC 41 1778 1976,46 3978 19811.

Purification of Inorganic and Metal-Organic Chemicals 371

Borane pyridine complex [ I I 0 - 5 1 - 0 ] M 92.9, m 8-10", 10-1lo, b 86"/7mm, 100- 101°/12mm, d:' 0.785. Dissolve in Et20 and wash with H20 in which it is insol. Evap Et20 and distil (gives better than 99.8% purity). Its vap pressure is less than O.lmm at room temp. [JACS 77 1506 19-55].

Borane triethylamine complex [ 1722-26-51 M 115.0, b 76"/4mm, 97.0°/12mm, d;' 0 . 7 8 . Distil in a vacuum using a 60cm glass helices packed column. [5.4CS 64 325 1942, 84 3407 1962; TET LE7T 4703 19681.

Borane trimethylamine complex [ 75-22-91 M 73.0, m 94-94S0, b 171°/atm. Sublimed using equipment described in JACS 59 780 1937. Its vapour pressure is 86mm at looo. Colourless hexagonal crystals varying from needles to short lumps, slightly soluble in H20 (1.48% at 30°), EtOH (1%), hexane (0.74%) but very soluble in EtzO, C6H6 and AcOH. Stable at 125O. [JACS 59 780 1939,104 325 19421.

Borane triphenyl see triphenyl borane.

Boron trichloride [10294-34-51 M 117.2, b 0°/476mm. Purified (from chlorine) by passage through two mercury-filled bubblers, then fractionally distd under vacuum. In a more extensive purification the nitrobenzene addition compound is formed by passage of the gas over nitrobenzene in a vacuum system at loo. Volatile impurities are removed from the crystalline yellow solid by pumping at -20°, and the BCl3 is recovered by warming the addition compound at 50°. Passage through a trap at -78O removes entrained nitrobenzene; the BC13 finally condensing in a trap at -112O [Brown and Holmes JACS 78 2173 19561. Also purified by condensing into a trap cooled in acetonemry-ice, where it was pumped for 15min to remove volatile impurities. It was then warmed, recondensed and again pumped.

Boron trifluoride [7637-07-21 M 67.8, b 111.8°/300mm. The usual impurities - bromine, BF5, HF and non-volatile fluorides - are readily separated by distn. Brown and Johannesen [JACS 72 2934 19501 passed BF3 into benzonitrile at Oo until the latter was satd. Evacuation to 10-5mm then removed all traces of SiF4 and other gaseous impurities. [A small amount of the BF3-benzonitrile addition compound sublimed and was collected in a U-tube cooled to -80°]. Pressure was raised to 20mm by admitting dry air, and the flask containing the BF3 addition compound was warmed with hot water. The BF3 evolved was passed through a -80° trap (to condense any benzonitriie) into a tube cooled in liquid air. The addition compound with anisole can also be used. For drying, BF3 can be passed through H2SO4 saturated with boric oxide. Fumes in moist air.

Boron trifluoride diethyl etherate [ 109-63- 71 M 141.9, b 67O/43mm, b 126°/760mm, d 1.154, n 1.340. Treated with a small quantity of ethyl ether (to remove an excess of this component), and then distd under reduced pressure, from CaH2. Fumes in moist air. TOXIC.

Bromine [7726-95-61 M 159.8, b 5 9 O , d 3.102, n 1.661. Refluxed with solid KBr and distd, dried by shaking with an equal volume of conc H2SO4, then distd. The H2SO4 treatment can be replaced by direct distn from BaO or P2O5 A more extensive purification [Hildenbrand et al. JACS 80 4129 19581 is to reflux ca 1L of bromine for lh with a mixture of 16g of Cr03 in 200ml of conc H2SO4 (to remove organic material). The bromine is distd into a clean, dry, glass-stoppered bottle, and chlorine is removed by dissolving ca 25g of freshly fused CsBr in 500ml of the bromine and standing overnight. To remove HBr and water, the bromine was then distd back and forth through a train containing alternate tubes of MgO and P2O5. HIGHLY TOXIC.

Bromine pentafluoride [7789-30-21 M.174.9, m -60S0, b 41.3O, d25 2.466. Purified via its KF complex, as described for chlorine trifluoride. HIGHLY TOXIC.

2-Bromoallyltrimethylsilane [81790-10-51 M 193.2, b 64-66°/10mm, 82-85°/58-60mm, di0 1.13. Fractionally distd through an efficient column. I t is flammable. [JACS 104 3733 6879 19821.

2-Bromo-1,3,2-benzodioxaborole [51901-85-0~ M 198.8, m 47", 51-53", b 76"/9mm. 20°/15mm for some time and then fractionally distil. [JCS 1529 19591.

Keep at

372 Purification of Inorganic and Metal-Organic Chemicals

Bromopyrogallol Red [16574-43-91 M 576.2, E 5.45 x lo4 a t 538nm (water pH 5.6-7.5). Recrystd from aqueous alkaline s o h (Na2C03 or NaOH) by pptn on acidification [Suk Coll Czech Chem Commun 31 3127 19661.

Bromosulfalein (disodium phenoltetrabromophthalein 3',3'-disulphonate) see Chapter 3.

Bromo trimethyl silane (trimethyl bromosilane) [2857-97-81 M 153.1, m -43.5O to -43.2O; b 40S0/200mm, 77.3O/735mm, 79O/744mm, 79.8-79.9O/754mrn, d i O 1.1805, d i O 1.190, n y 1.422. Purified by repeated fractional distillation and stored in sealed ampoules in the dark. [JACS 75 1583 19531. Also fractionally distd through a 15 plate column (0.8 x 32cm packed with 1/16in single turn helices from Pt-Ir wire). [JACS 68 1161 1946; 70 433 19481.

n-Butylmercuric chloride [543-63-51 M 293.1, m 130O. Crystd from EtOH.

n-Butylphenyl n-butylphosphonate [36411-99-1] M 270.3. Crystd three times from hexane as its compound with uranyl nitrate. See tn-n-butyl phosphate below.

p-tert-Butylphenyl diphenyl phosphate [981-40-81 M 382.4, b 261°/6mm, nZ5 1.5522. Purified by vacuum distn, and percolation through an alumina column, followed by passage through a packed column maintained at 150° to remove residual traces of volatile materials in a counter-current stream of N2 at reduced pressure [Dobry and Keller JPC61 1448 1953.

Butyl phosphate see tri-n-butyl phosphate below.

n-Butylstannoic acid [PhSn(OH)3] [22719-01-31 M 208.8. Purified by adding excess KOH in CHC13 to remove n-BuSn(OH)Cl2 and n-BuSn(OH)2C1, and isolated by acidification [Holmes et al. JACS 109 1408 1983.

tert-Butyldimethylsilyl chloride [ I 8 1 62-48-6 1 M 150.7, m 87-89O, 92S0, b 125°/760mm. Fractionally distd at atmospheric pressure. [JACS 76 1030 1954; 94 6190 19721.

Cacodylic acid [75-60-5] M 138.0, m 195-196O. Crystd from warm EtOH (3ml/g) by cooling and filtering. Dried in vacuum desiccator over CaC12. Has also been twice recrystd from propan-2-01. [Koller and Hawkridge JACS 107 7412 19851.

Cadion [ 1-(4-nitrophenyl)-3-(4-phenylazophenyl)-triazene] [5392-67-61 M 346, m 1 9 8 O . Commercial cadion is purified by recrystn from 95% EtOH and dried. It is stable in 0.2 N KOH (in 20% aqueous EtOH) at 25O. It is a sensitive reagent for Cd, and the Cd complex has hmax (EtOH) 475nm. [Australian Chem Inst J Proc 4 26 1937 ; ACA 19 377 19581.

Cadmium [7440-43-91 M 112.4. Oxide has been removed by filtering the molten metal, under vacuum through quartz wool.

Cadmium acetate [543-90-81 M 230.5. Crystd twice from anhydrous acetic acid and dried under vacuum for 24h at looo.

Cadmium bromide (4Hz0) [7789-42-61 M 344.2. Crystd from water (0.6mVg) between looo and Oo, and dried at 1100.

Cadmium chloride [10108-64-21 M 183.3, m 568O. Crystd from water (lml/g) by addition of EtOH and cooling.

Purification of Inorganic and Metal-Organic Chemicals 373

Cadmium fluoride [7790-79-61 M 150.4, m >lOOOo. Crystd by dissolving in water at room temperature (25mVg) and heating to 60°.

Cadmium iodide [7790-80-91 M 366.2, m 388O. Crystd from ethanol (2ml/g) by partial evaporation.

Cadmium ionophore I [N,N,N',N'-tetramethyl-3,6-dioxooctanedi-(thioamide)] [73487-00-01 M 432.7, m 35-36O. Wash well with pet ether, then several times with 2N HCl (if it has a slight odour of pyridine) then H20 and dry in a vacuum over H2S04. It is a polar selectrophore for Cd. [HCA 63 217 19801.

Cadmium lactate [16039-SS-7/ M 290.6. Crystd from water (10ml/g) by partial evapn in a desiccator.

Cadmium nitrate (4H20) [10022-68-11 M 308.5. Crystd from water (0.5ml/g) by cooling in ice-salt.

Cadmium potassium iodide [13601-63-31 M 532.2. Crystd from ethanol by partial evapn.

Cadmium salicylate [ I901 0- 79-81 M 248.5, Cadmium sulphate [10124-36-41 M 769.5. Crystd from distd water by partial evapn in a desiccator.

Caesium compounds see cesium compounds

Calcein [2',7'-bis-{N, N-di(carboxymethyl)aminomethyl}fluorescein] sodium salt [ I461 - 1 S - O] M 666.5. Dissolve in distilled H20 and acidify with dilute HCI to pH 3.5. Filter off the solid acid and wash well with H20. Redissolve ca log in 300ml H20 containing 12g of NaOAc. Ppte again by adding HCl, filter and wash with H20. Add the solid to 200ml of EtOH stir for l h and filter. Repeat the EtOH wash and dry the bright yellow solid in a vacuum. This acid decomposes on heating at ca 180°. See below for the prepn of the Na salt. [AC 28 882 19561. Dissolve in H20 and acidify with 3N HCl to pH 3.5. Collect the solid and wash with H20. The air-dried ppte is extracted with 70% aqueous EtOH, filtered hot and cooled slowly. Fine yellow needles of the acid crystallise out, are filtered and dissolved in the minimum quantity of 0.01N NaOH and reppted with N HCI to pH 3.5. It is then recrystd from 70% aqueous EtOH (3x). The final product (acid) is dried at SOo in a vacuum for 24h, m >300°dec. It contains one mol of water per mol of acid ( C ~ O H ~ & O ~ ~ . H ~ O ) . The product is pure as revealed by electrophoresis at pH 5.6 and 8.6, and by TLC in isoBuOH-isoPrOH-AcOH-H~0 (60:60:5:5 by vol) or isoPrOH or pH 8.0 borate buffer. [AC 31 456 19591. The Na salt is prepared by dissolving in H 2 0 containing 2 mols of NaOH per mol of acid reagent and lyophilizing.

Calcium 17440-70-21 M 40.1, m 8 4 5 O . Cleaned by washing with ether to remove adhering paraffin, filed in an argon-filled glove box, and washed with ethanol containing 2% of conc HCl. Then washed with dry ethanol, dried in a vacuum and stored under pure argon [Addison, Coldrey and Halstead, JCS 3868 19621.

Calcium acetate [62-54-41 M 158.2. Crystd from water (3ml/g) by partial evapn in a desiccator.

Calcium benzoate (3H20) [2090-05-3] M 336.4. Crystd from water (lOm/g) between 90° and Oo.

Calcium bromide (H20) [62648-72-01 M 217.9. Crystd from ethanol or acetone.

Calcium butyrate [5743-36-21 M 248.2. Crystd from water (5ml/g) by partial evapn in a desiccator.

Calcium carbamate [543-88-41 M 160.1. Crystd from aqueous ethanol

Calcium chloride (anhydrous) [10043-S2-4/ M 111.0, m 772O, b >1600°, di5 2.15. Available as fused granules or cubic crystals. It is very hygroscopic. Very soluble in H 2 0 (exothermic), and EtOH. Loses H20 at 20O0 so it can be dried at high temperatures to dehydrate. Store in a tightly closed container.

Calcium chloride (2H20) [22691-02-71 M 147.0. Crystd from ethanol.

374 Purification of Inorganic and Metal-Organic Chemicals

Calcium dithionite 113812-88-91 M 168.2. Crystd from water, or water followed by acetone and dried in air at room temperature.

Calcium D-gluconate monohydrate [299-28-51 M 448.4, [a] :& + l l . O o , [a] Lo+9.O0 (c 1.2, HzO). It is sol in H20 (3.5g in lOOg at 25O). Dissolve in H20, filter and ppte by adding MeOH. Filter off solid and dry in a vacuum at 85O. Alternatively, dissolve in H20, filter (from insol inorganic Ca) and evaporate to dryness under vacuum at 85O. [J.Amer.Phann.Assoc 41 366 19521.

Calcium D-heptagluconate dihydrate H20). Purified same as calcium D-gluconate.

[17140-60-21 M 526.4, [a] ::a +5.2O, [a]io+4.4O (c 5,

Calcium formate [544-17-21 M 130.1. Crystd from water (Smug) by partial evaporation in a desiccator.

Calcium hexacyanoferrate (11) (11HzO) [13821-08-41 M 490.3. Recrystd three times from conductivity H20 and air dried to constant weight over partially dehydrated salt. [TFS 45 855 19491. Alternatively the Ca salt can be purified by pptn with absolute EtOH in the cold (to avoid oxidation) from an air-free saturated aqueous soln. The pure lemon yellow crystals are centrifuged, dried in a vacuum desiccator first over dry charcoal for 24h, then over partly dehydrated salt and stored in a dark glass stoppered bottle. No deterioration occurred after 18 months. No trace of Na, K or NH4 ions could be detected in the salt from the residue after decomposition of the salt with conc H2SO4. Analyses indicate 1 lmols of H20 per mol of salt. The solubility in H20 is 36.45g (24.9O) and 64.7g(44.72O) per lOOg of solution. [JCS 50 19261.

Calcium hydroxide [1305-62-01 M 74.1. Heat analytical grade calcium carbonate at 1000° during lh. Allow the resulting oxide to cool and add slowly to water. Heat the suspension to boiling, cool and filter through a sintered glass funnel of medium porosity (to remove soluble alkaline impurities). Dry the solid at 1 loo and crush to a uniformly fine powder.

Calcium iodate [7789-80-21 M 389.9. Crystd from water (lOOml/g).

Calcium iodide (HzO) [71626-98-71 M 293.9. Dissolved in acetone, which was then diluted and evaporated. This drying process was repeated twice, then the CaI2 was crystd from acetone-ethyl ether and stored over P2O5. Very hygroscopic when anhydrous [Cremlyn et al. JCS 528 19581.

Calcium ionophore I (ETH 1001) [58801-34-61 M 685.0. This is a neutral Ca selectophore. It can be purified by thick layer (2mm) chromatography (Kieselgel F245) and eluted with Me2CO-CHC13 (2:l). [HCA 56 1780 19731.

Calcium ionophore I1 (ETH 129) [74267-27-91 M 460.7, m 153-154O. Recrystd from Me2CO. It forms 1 :2 and 1 :3 metamigand complexes with Mg++ and Ca++ ions respectively, and induces selectivity in membranes for Ca++ over Mg++ by a factor of ca 104. [HCA 63 191 19801.

Calcium ionophore I11 [A23187 calcimycin] [52665-69- 71 M 523.6, m 181-182O, [a]? -56.0° (c 1, CHCl3). Recrystallises from Me2CO as colourless needles. Protect from light and moisture, store in a refrigerator. Soluble in Me2SO or EtOH and can be stored for 3 months without loss of activity. Mg and Ca salts are soluble in organic solvents and cross biological membranes. It has a pKa of 6.9 in 90% Me2SO. The Ca complex cryst from 50% EtOH as colourless prisms. Highly TOXIC [Annual Reviews of Biochemistry 45 501 1976; JACS 96 1932 1974, J Antibiotics 29 424 19761.

Calcium isobutyrate [533-90-41 M 248.2. Crystd from water (3mUg) by partial evapn in a desiccator.

Calcium lactate (5H20) [814-80-21 M308.3. Crystd from warm water (1OmUg) by cooling to Oo.

Calcium nitrate (4Hz0) [13477-34-41 M 236.1, m 45O. Crystd four times from water (0.4ml/g) by cooling in a CaC12-ice freezing mixture. The tetrahydrate was dried over conc H2S04 and stored over P2O5, to give the anhydrous salt.

Purification of Inorganic and Metal-Organic Chemicals 375

Calcium nitrite (2H20) [13780-06-81 M 150.1. Crystd from hot water (1.4ml/g) by adding ethanol and cooling.

(+)-Calcium pantothenate (H20) [63409-48-31 M 476.5, [a1546 +26S0 (c 5, H20) . Crystd from methanol.

20

Calcium permanganate (4H20) [I01 18-76-01 M 350.0. Crystd from water (3.3ml/g) by partial evapn in a desiccator.

Calcium propionate [4075-81-41 M 186.2. Crystd from water (2mVg) by partial evapn in a desiccator.

Calcium salicylate (2H20) [824-35-11 M 350.4. Crystd from water (3ml/g) between 90° and Oo

Calcium sulphate dihydrate [IOIOI-41-41 M 172.1, d2.32. Loses only part of its H20 at 100-150°. Soluble in H20 and very slowly soluble in glycerol. Insoluble in most organic solvents.

Calcium sulphate hemihydrate Sol in H20 (0.2 parts/100 at 18.75O). Completely dehydrated >650°. Dry below 300° to give a solid with estimated pore size ca 38% of vol. Anhydrous CaS04 has high affinity for H20 and will absorb 6.6% of its weight of H20 to form the hemihydrate (gypsum). It sets to a hard mass with H20, hence should be kept in a tightly sealed container.

[10034-76-11 M 145.2.

Calcium thiosulphate M 152.2. Recrystd from water below 60° in a N2 atmosphere, followed by drying with EtOH and Et20. Stored in a refrigerator. [Pethybridge and Taba JCSFT I 78 1331 19821.

(4-Carbamy1phenylarsylenedithio)diacetic acid [531-72-61 M 345.1. Crystd from MeOH or EtOH.

Carbonate ionophore I [ETH 60101 (heptyl-4-trifluoroacetylbenzoate) [ 129476-47- 71 M 316.3, b 170°/0.02 Torr, d0.909. Purified by flash chromatography (2g of reagent with 30g of Silica Gel 60) and eluted with EtOAchexane (1 : 19). The fractions that absorbed at 260nm were pooled, evapd and dried at room temp (10.3 Torr). The oily residue was distd in a bubbled-tube apparatus ( 170°/0.02 Torr). Its IR (CHC13) had peaks at 1720, 1280, 940cm-* and its sol in tetrahydrofuran is 50mg/OSml. It is a lipophilic neutral ionophore selective for carbonate as well as being an optical humidity sensor. [ACA 233 41 19901.

Carbon dioxide [124-38-91 M 44.0, sublimes at -78.5O. Passed over CuO wire at 800° to oxidise CO and other reducing impurities (such as H2), then over copper dispersed on Kieselguhr at 180° to remove oxygen. Drying at -78O removed water vapour. Final purification was by vacuum distn at liquid nitrogen temperature to remove non-condensable gases [Anderson, Best and Dominey JCS 3498 19621. Sulphur dioxide can be removed at 450° using silver wool combined with a plug of platinized quartz wool. Halogens are removed by using Mg, Zn or Cu, heated to 4 5 0 O .

Carbon disulphide, see entry in Chapter 3.

Carbon monoxide [630-08-01 M 28.0, b -191.5O. Iron carbonyl is a likely impurity in CO stored under pressure in steel tanks. It can be decomposed by passage of the gas through a hot porcelain tube at 350-400O. Passage through alkaline pyrogallol soln removes oxygen (and C02). Removal of C02 and water are effected by passage through soda-lime followed by Mg(C104)2. Carbon monoxide can be condensed and distd at -195O. HIGHY POISONOUS gas.

Carbon tetrachloride, see entry in Chapter 3.

Carbonyl bromide [593-95-31 M 187.8. Purified by distn from Hg and from powdered Sb to remove free bromine, then vacuum distd to remove volatile SO2 (the major impurity) [Carpenter et al. JCSFT 2 384 1973.

376 Purification of Inorganic and Metal-Organic Chemicals

Carbonyl sulphide [463-58-11 M 60.1. Purified by scrubbing through three consecutive fritted washing flasks containing conc NaOH at Oo. Then freeze-pumped repeatedly and distd through a trap packed with glass wool and cooled to - 1 30° (using an n-pentane slurry).

Celite 545 (diatomaceous earth) [12279-49-1]. Stood overnight in conc HCl after stirring well, then washed with distilled water until neutral and free of chloride ions. Washed with methanol and dried at 50°.

Ceric ammonium nitrate [16774-21-31 M 548.2. Ceric ammonium nitrate (125g) is warmed with lOOml of dilute HNO3 (1:3 v/v) and 40g of NH4N03 until dissolved, and filtered off on a sintered-glass funnel. The solid which separates on cooling in ice is filtered off on a sintered funnel (at the pump) and air is sucked through the solid for 1-2 h to remove most of the nitric acid. Finally, the solid is dried at 80-85O.

Cerous acetate [537-00-81 M 317.3. Crystd twice from anhydrous acetic acid, then pumped dry under vacuum at 100° for 8h.

Cesium bromide [7787-69-11 M 212.8, m 636O, b c a 1300°, d 4.44. Very soluble in B 2 0 , soluble in EtOH but insoluble in Me2CO. Dissolve in the minimum volume of H20, filter and ppte by adding Me2CO. Filter solid and dry at looo. Also recrystd from water (0.8mVg) by partial evaporation in a desiccator.

Cesium carbonate [534-17-81 M 325.8. Crystd from ethanol (IOml/g) by partial evaporation.

Cesium chloride [7647-17-81 M 168.4, m 645O, b 1303O, d 3.99. Soluble in H20 but can be purified by crystn from H20 [sol in g per cent: 162.3(0.7O), 182.2(16.2O) and 290(at bp 119.4O)J and dried in high vac. Sol in EtOH and is deliquescent, keep in a tightly closed container. [Handbook of Preparative Inorganic Chemistry (ed Brauer) Vol I 951 19631. For further purification of CsCI, a conc aqueous soln of the practically pure reagent is treated with an equivalent weight if I2 and C12 bubbled into the soln until pptn of CsC12I ceased. Recrystn yields a salt which is free from other alkali metals. It is then decomposed to pure CsCl on heating. [JACS 52 3886 19301. Also rerystd from acetone-water, or from water (0.5mVg) by cooling in CaC12/ice. Dried at 7 8 O under vacuum.

Cesium chromate [13454-78-91 M 381.8. Crystd from water (1.4mVg) by partial evapn in a desiccator.

Cesium fluoride [13400-13-01 M 151.9. Crystd from aqueous soln by adding ethanol.

Cesium iodide [7789-17-51 M 259.8. Crystd from warm water (lml/g) by cooling to - 5 O .

Cesium nitrate [7789-18-61 M 194.9. Crystd from water (0.6mUg) between 100° and Oo.

Cesium oleate [31642-12-31 M 414.4. Crystd from ethyl acetate, dried in an oven at 40° and stored over p205.

Cesium perchlorate [13454-84-7 M 232.4. Crystd from water (4ml/g) between 100° and Oo.

Cesium perfluoro-octanoate [ 17125-60-91 M 546.0. Recrystd from a butanol-petroleum ether mixture, dried in an oven at 400 and stored over P2O5 under vacuum.

Cesium sulphate [10294-54-91 M 361.9. Crystd from water (0.5ml/g) by adding ethanol and cooling.

Chloramine-T [127-65-11 M 227.6, m 168-170°. Crystd from hot water (2ml/g). Dried in a desiccator over CaC12 (protect from sunlight).

Chlorine [7782-50-51 M 70.9. Passed in succession through aqueous KMn04, dilute H2SO4, conc H2SO4, and a drying tower containing Mg(C10&. Or, washed with water, dried over P2O5 and distd from bulb to bulb. HIGHLY TOXIC.

Purification of Inorganic and Metal-Organic Chemicals 377

Chlorine trifluoride [7790-91-21 M 92.5, b 12.1O. Impurities include chloryl fluoride, chlorine dioxide and hydrogen fluoride. Passed first through two U-tubes containing NaF to remove HF, then through a series of traps in which the liquid is fractionally distd. Can be purified via the KF complex, KClF4, formed by adding excess ClF3 to solid KF in a stainless steel cylinder in a dry-box and shaking overnight. After pumping out the volatile materials, pure ClF3 is obtained by heating the bomb to 100-150° and condensing the evolved gas in a -196O trap [Schack, Dubb and Quaglino Chemistry and Industry (London)) 545 19671. HIGHLY TOXIC.

2-Chloro-1,3,2-benzodioxaphosphole-2-oxide see 1,2-phenylenephosphorochloridate.

Chloro diisopropyl silane see diisopropyl chlorosilane.

4-Chloromercuribenzoic acid [59-85-8] M 357.2, m >300°. Its suspension in water is stirred with enough 1M NaOH to dissolve most of it: a small amount of insoluble matter is removed by centrifugation. The chloromercuribenzoic acid is then ppted by adding 1M HCI and centrifuged off. The pptn is repeated twice. Finally, the ppte is washed three times with distilled water (by centrifuging), then dried in a thin layer under vacuum over P2O5 [Boyer JACS 76 4331 19541.

Chloromethylphosphonic acid dichloride [ 1983-26 -21 M 167.4, b 50°/0.5mm, 52- 53(59)O/2mm, 63-65O/3mm, 78-79O/lOrnm, 87-88O/15rnm, 102-103°/30mm, di0 1.638, nko 1.4971. Fractionally distd using a short Claisen column and redistd. The aniline salt has m 199-201O. The 31P NMR has a line at -38+2 ppm from 85% H3P04. [Kinnear and Perren J C S 3437 1952; NMR: JACS 78 5715 1956; JOC22 462 19571.

2-Chloro-2-oxo-1,3,2-dioxaphospholane [6609-64-91 M 142.5, m 12-14O, b 89-91°/0.8mm, d;O1.549, n y 1.448. Should be distd at high vacuum as some polymerisation occurs on distn. It has IR bands at 3012, 2933, 1477, 1366, 1325, 1040, 924 and 858 cm-'. In H20 at looo it is hydrolysed to HOCH2CH20P03H2 in 30min [IR: Cox and Westheimer JACS 80 5441 19581.

2-Chl~ophenyl diphenyl phosphate [I 15-85-51 M 360.7, b 236O/4rnm, n25 1.5707. Purified by vacuum distn, percolated through a column of alumina, then passed through a packed column maintained by a countercurrent stream of nitrogen at reduced pressure [Dobry and Keller J P C 61 1448 1953.

Chlorosulphonic acid [7790-94-51 M 116.5, b 151-152°/750mm, d4 1.753, n 1.4929. Distd in an all-glass apparatus, taking the fraction boiling at 156-158O. Reacts EXPLOSIVELY with water.

Chloro-(2,2':6',2'-terpyridine)platinum (11) chloride (2Hz0) [60819-00-31 M 535.3. Recrystd from hot dilute HCl and cooling to give the red dihydrate. The trihydrate crysts slowly from a cold aq soln and is air dried. The red dihydrate can be obtained from the trihydrate by desiccation over conc H2SO4, by washing with EtOH or by precipitating from a warm aq soln with HCI. The dihydrate is also formed by decomposing the black trihydrate form by heating in water (slowly), or more rapidly with hot 2N HCI. [JCS 1498 19341.

Chloro-tri-isopropyl titanium [20717-86-61 M 260.6, m 45-50°, b 61-65°/0.1mm. Distd under vacuum and sets slowly to a solid on standing. Stock reagents are made by dissolving the warm liquid in pentane, toluene, Et20, THF, CH2C12,, and can be stored in pure state or in soln under dry N2 for several months. The reagent is hygroscopic and is hydrolysed by H20. [ B 118 1421 19851.

Chloro trimethyl silane see trimethyl chlorosilane.

Chloro triphenyl silane (triphenyl chlorosilane) [ 76-86-81 M 294.9, m 90-92O, 91-93O, 94- 9S0, 97-99O, b 156°/lmm, 161°/0.6mm. Likely impurities are tetraphenylsilane, small amounts of hexaphenyldisiloxane and traces of triphenylsilanol. Purified by distn at 2mm, then crystd from EtOH-free CHC13, and from pet ether (b 30-60°) or hexane by cooling in a Dry-ice/acetone bath. [JCS 3671 1957; JACS 72 447 1 1958,77 6395 I955,79 1843 19571.

378 Purification of Inorganic and Metal-Organic Chemicals

Chromazurol S [1667-99-81 M 605.3. Purified by paper chromatography using n-butanol, acetic acid and water (7:3: 1). First and second spots extracted.

Chromic chloride (anhydrous) [10025-73-71 M 158.4. Sublimed in a stream of dry HCl. Alternatively, the impure chromic chloride (1OOg) was added to 1L of 10% aq K2Cr207 and several millilitres of conc HCl, and the mixture was brought to a gentle boil with constant stirring for 10 min. (This removed a reducing impurity.) The solid was separated, and washed by boiling with successive 1L lots of distilled water until the wash water no longer gave a test for chloride ion, then dried at 1 loo [Poulsen and Garner JACS 81 2615 19591.

Chromionophore I 52941 [ 9 - d ie t hy I am i n o - 5 - O C t a d e ca n o y I - im i n o - 5 - H - benzo[a]phenoxazine] [125829-24-51 M 583.9. Purified by flash chromatography (Silica Gel) and eluted with EtOAc. The coloured fractions are pooled, evaporated and recrystd from EtOAc. It is a lipohilic chromionophore and is a selectophore for K and Ca ions. [ A C 62 738 19901.

[ETH

Chromium (111) acetylacetonate [21679-31-21 M 349.3, m 212-216O, 216O. Purified by dissolving 6g in hot C6H6 (20ml) and adding 75ml of pet ether slowly. Cool to room temp then chill on ice, filter off and dry in air to give 2.9g. Sol in heptane, C6H6 , toluene and pentane-2,4-dione at 20-40°. It forms a 1:2 complex with CHC13. [Inorg Synth 5 130 1957; J A C S 8 0 1839 19581.

Chromium ammonium sulphate (12H20) [34275- 72-41 M 478.4. Crystd from a saturated aqueous soln at 55O by cooling slowly with rapid mechanical stirring. The resulting fine crystals were filtered on a Biichner funnel, partly dried on a porous plate, then equilibrated for several months in a vacuum desiccator over crude chromium ammonium sulphate (partially dehydrated by heating at 1 OOo for several hours before use)[Johnson, Hu and Horton JACS 75 3922 19531.

Chromium (11) Chloride (anhydrous) [10049-05-5] M 122.9, m 824O, di4 2.75. Obtained from the dihydrate by heating in vucuo at 180O. It is a very hygroscopic white powder which dissolves in H20 to give a sky blue solution. Stable in dry air but oxidises rapidly in moist air and should be stored in air tight containers. It sublimes at 800° in a current of HCl gas and cooled in the presence of HCl gas. Alternatively it can be washed with air-free Et2O and dried at 1 10- 1200. [Inorg Synth 3 150 19501.

Chromium hexacarbonyl [13007-92-61 M 220.1, d 1.77. Wash with cold EtOH then Et20 and allow to dry in air. Alternatively recrystallise from dry Et20. This is best accomplished by placing the hexacarbonyl in a Soxhlet extractor and extracting exhaustively with dry Et20. Pure Cr(C0)6 is filtered off and dried in air. Completely colourless refracting crystals are obtained by sublimation at 40-50°/

Purification of Inorganic and Metal-Organic Chemicals 379

23 thoroughly, dry and evaporate. Recryst Erom EtOAc. The hepta-acetate has m 214O, [a] [TET 23 421 1967; JACS 91 5896 19691.

-200 (c 1,EtOH).

Chromyl chloride [14977-61-81 M 154.9, b 115.7O, d 1.911. pressure. TOXIC.

Purified by distn under reduced

Cisplatin see cis-diamminedichloroplatinum(I1).

Claisen alkali (alkali Claisen). Prepared from KOH (35g) in H20 (25ml) and diluted to lOOml with MeOH.

Cobalt (11) meso-5.10,15,20-tetraphenylporphine complex [I41 72-90-81 M 671.7. Brown crystals from Et20 or CHC13-MeOH (cf iron chloride complex). Recrystd by extraction (Soxhlet) with C6H6. Sol in most organic solvents except MeOH and pet ether. [W, IR: JACS 70 1808 1948; 81 5111 19591.

Cobaltous acetate (4H20) 16147-53-11 M 249.1. Crystd several times as the tetrahydrate from 50% aqueous acetic acid. Converted to the anhydrous salt by drying at 80°/lmm for 60h.

Cobaltous acetylacetonate [14024-48-71 M 257.2, m 172O. Crystd from acetone.

Cobaltous ammonium sulphate (6H2O) [ I 3596-46-81 M 395.5. Crystd from boiling water (2mYg) by cooling. Washed with ethanol.

Cobaltous bromide (6H2O) [7789-43-71 M 326.9. Crystd from water (1mYg) by partial evaporation in a desiccator.

Cobaltous chloride (6H2O) [7791-13-71 M 237.9. A saturated aqueous soln at room temperture was fractionally crystd by standing overnight. The first half of the material that crystd in this way was used in the next crystn. The process was repeated several times, water being removed in a dry-box using air filtered through glass wool and dried over CaC12 [Hutchinson JACS 76 1022 19541. Has also been crystd from dilute aq HCl.

Cobaltous nitrate (6H2O) [10026-22-91 M 291.0. Crystd from water (lml/g), or ethanol (lml/g), by partial evapn.

Cobaltous perchlorate (6H2O) [13455-31-7] M 365.9. Crystd from warm water (0.7mVg) by cooling.

Cobaltous potassium sulphate [13596-22-01 M 329.4. Crystd from water (lml/g) between 50° and Oo.

Cobaltous sulphate (7H20) [10124-43-31 M 281.1. Crystd three times from conductivity water (1.3mYg) between 100° and Oo.

Copper (I) thiophenolate [1192-40-1] M 172.7, m ca 280O. The Cu salt can be extracted from a thimble (Soxhlet) with boiling MeOH. It is a green-brown powder which gives a yellow-green soln in pyridine. Wash with EtOH and dry in a vacuum. It can be ppted from a pyridine soh by addition of H20, collect ppte, wash with EtOH and dry in a vacuum. [S 662 1974; JACS 79 170 1957; B 90 425 19.571.

12-Crown-4 (lithium ionophore V, 1,4,7,10-tetraoxacyclododecane) [294-93-91 M 176.2, m 17O. The distilled crude product had to be crystd from pentane at -2OO to remove acyclic material. It is then dried over P2O5. [Acra Chem Scand 27 3395 19731.

Cupferon (N-nitroso-N-phenylhydroxylamine) ammonium salt [I 35-20-61 M 155.2, m 150- 155O(dec), 162.5-163S0, 163-164O. Recrystd twice from EtOH after treatment with Norite and finally once with EtOH. The dried crystals are stored in the dark over solid ammonium carbonate. A standard s o h (ca 0.05M prepared in air-free H20) is prepared daily from this material for analytical work and is essentially 100% pure. [AC 26 1747 19541. It can also be washed with Et20, dried and stored as stated. In a sealed, dark

380 Purification of Inorganic and Metal-Organic Chemicals

container it can be stored for at least 12 months without deterioration. hmax 260nm (CHC13). [Urg Synth Col Vol 1 177 1948; JACS 78 4206 19561. Possible CARCINOGEN.

Cupric acetate (H20) [6046-93-1] M 199.7. Crystd twice from warm dilute acetic acid solns (Smug) by cooling.

Cupric ammonium chloride (2H20) [10534-87-91 M 277.5. Crystd from weak aqueous HCl (lml/g).

Cupric benzoate [533-01-71 M 305.8. Crystd from hot water.

Cupric bromide [7789-45-91 M 223.4. Crystd twice by dissolving in water (140ml/g), filtering to remove any Cu2B1-2, and concentrating under vac at 30° until crystals appeared. The cupric bromide was then allowed to crystallise by leaving the soln in a vac desiccator containing P2O5 [Hope, Otter and Prue JCS 5226 19601.

Cupric chloride [7447-39-41 M 134.4. Crystd from hot dilute aqueous HCl (0.6mVg) by cooling in a CaC12-ice bath. Dehydrated by heating on a steam-bath under vacuum.

Cupric lactate (HzO) [814-81-31 M 295.7. Crystd as the monohydrate from boiling water (3ml/g) by cooling.

Cupric nitrate (3H20) [19004-19-41 M 241.6. Crystd from weak aqueous HNO3 (0.5mUg) by cooling from room temperature. The anhydrous salt can be prepared by dissolving copper metal in a 1: 1 mixture of liquid NO2 and ethyl acetate and purified by sublimation [Evans et al. JCSFT 175 1023 19791.

Cupric oleate [1120-44-11 M 626.5. Crystd from ethyl ether.

Cupric perchlorate (6H2O) [13770-18-81 M 370.5. Crystd from distilled water.

Cupric phthalocyanine [147-14-81 M 576.1. Precipitated twice from conc H2SO4 by slow dilution with water. Also purified by two or three sublimations in an argon flow at 300-400Pa.

Cupric sulphate [7758-98-71 M 159.6. After adding 0.02g of KOH to a litre of nearly saturated aq soln, it was left for two weeks, then the ppte was filtered on to a fibreglass filter with pore diameter of 5-15 microns. The filtrate was heated to 90° and allowed to evaporate until some CuS04.5H20 had crystd. The soln was then filtered hot and cooled rapidly to give crystals which were freed from mother liquor by filtering under suction [Geballe and Giauque JACS 74 3513 19521. Alternatively crystd from water (0.6ml/g) between 100O and Oo.

Cupric trifluoromethylsulphonate (copper I1 triflate) [34946-82-21 M 361.7. Dissolve in MeCN, add dry Et20 until cloudy and cool at -2OO in a freezer. The light blue ppte is collected and dried in a vacuum oven at 130°/20mm for 8h. It has hmax 737nm (E 22.4M-'cm-') in AcOH. [JACS 95 330 19731. It has also been dried in a vessel at O.1Torr by heating with a Fischer burner [JUC 43 3422 19781. It has been dried at 1 10-120°/5mm for lh before use and forms a benzene complex which should be handled in a dry box because it is air sensitive [Chem Pharm Bull Japan 28 262 1980; JACS 95 330 19731.

Cuprous bromide [7787-70-41 M 286.9. Purified as for cuprous iodide but using aqueous NaBr.

Cuprous bromide dimethylsulphide complex [54678-23-81 M 205.6, m ca 13S0(dec). Purified by recrystn in the presence of Me2S. A soln of the complex (1.02g) in M2S (5ml) is slowly diluted with hexane (20ml) and the pure colourless prisms of the complex (0.96g) separate and are collected and dried, m 124-129Odec. The complex is insoluble in hexane, Et20, Me2C0, CHC13 and CC14. It dissolves in DMF and DMSO but the soln becomes hot and green indicating dec. It dissolves in C6H6, Et20, MeOH and CHC13 if excess of Me2S is added a colourless soh is obtained. [ J O C 40 1460 19751. Prior to use, the complex was dissolved in Me2S and evaporated to dryness in the weighed reaction flask [J Organornet Chem 228 321 19821.

Purification of Inorganic and Metal-Organic Chemicals 381

Cuprous chloride [7758-89-61 M 99.0. Dissolved in strong HCl, ppted by dilution with water and filtered off. Washed with ethanol and ethyl ether, then dried and stored in a vacuum desiccator [Osterlof Acta Chem Scand 4 375 19501. Alternatively, to an aq. soh of CuC12.2H2O was added, with stirring, an aqueous soln of anhydrous sodium sulphite. The colourless product was dried at 80° for 30min and stored under Nz. CuC12 can be purified by zone-refining [Hall et a]. JCSFT I79 243 19831.

Cuprous cyanide [544-92-31 M 89.6. Wash thoroughly with boiling H20, then with EtOH. Dry at 100° to a fine soft powder. [JCS 79 19431.

Cuprous iodide M 190.5, m 605O, b 1336O, di5 5.63. It can be freshly prepared by dissolving an appropriate quantity of CuI in boiling saturated aqueous NaI over 30min. Pure CuI is obtained by cooling and diluting the s o h with water, followed by filtering and washing sequentially with H20, EtOH, EtOAc and Et20, pentane, then drying in vacuo for 24h [Dieter, JACS 107 4679 19851. Alternatively wash with H20 then EtOH and finally with Et20 containing a little iodine. Traces of H20 are best removed first by heating at 1 loo and then at 4OOO. Exess of I2 is removed completely at 400O. It dissolves in Et20 if an amine is present to form the amine complex. [Chemistry and Industry (London) 1180 19571.

[7681-65-41

Cuprous iodide trimethylphosphite [34836-53-81 M 314.5, m 175-177O, 192-193O. Cuprous iodide dissolves in a C6H6 s o h containing trimethylphosphite to form the complex. The complex crystallises from C6H6 or pet ether. [ B 38 1171 1905; Bull Chem Soc Japan 34 1177 19611.

Cuprous thiocyanate [18223-42-21 M 121.6. Purified as for cuprous iodide but using aq NaSCN.

Cyanamide [420-04-21 M 42.0, m 43O, 4S0, 46O, b 85-87°/0.5mm. Purified by placing c a 15g in a Soxhlet thimble and extracting exhaustively (2-3h) with two successive portions of EtzO (400m1, saturated with H20 by shaking before use) containing two drops of N-acetic acid. Two successive portions of Et2O are used so that the NH2CN is not heated for too long. Each extract is dried over Na2S04(30g), then combined and evaporated under reduced pressure. The NH2CN may be kept unchanged at Oo in Et2O soh in the presence of a trace of AcOH. Extracts from several runs may be combined and evaporated together. The residue from evaporation of an Et20 s o h is a colourless viscous oil which sets to a solid, and can be recrystd from a mixture of 2 parts of C6H6 and 1 part of Et20. Concentrating an aqueous s o h of NH2CN at high temps causes EXPLOSIVE polymerisation. It has a pKa29 of 1.1 in H20. [Org Synth Col Vol IV 645 1963; Inorg Synth 3 39 1950; JOC 23 613 19581.

Cyanogen bromide [506-68-31 M 105.9, m 49-51°, b 60-62°/atm. All operations with this substance should be performed in a very efficient fume cupboard - it is very POISONOUS and should be handled in small amounts. Fresh commercial material is satisfactory for nearly all purposes and does not need to be purified. I t is a white ctystalline solid with a strong cyanide odour. If it is reddish in colour and partly liquid or paste-like then it is too far gone to be purified, and fresh material should be sought. It can be purified by distn using small amounts at a time, and using a short wide-bore condenser because it readily solidifies to a crystalline white solid and may clog the condenser. An appropriate gas mask should be used when transferring the molten solid from one container to another and the operation should be done in an efficient fume cupboard. The melting point (m 49-51O) should be measured in a sealed tube. [Org Synth Col Vol 11, 150 19481.

Cyanogen iodide [506-78-51 M 152.9, m 146-147O. This compound is POISONOUS and the precautions for cyanogen bromide (above) apply here. The reagent (ca 5.9g) is dissolved in boiling CHC13 (15ml), filtered through a plug of glass wool into a 25ml Erlenmeyer flask. Cool to room temperature for 1 Smin, then place in an ice-salt bath and cool to -loo . This cooling causes a small aqueous layer to separate as ice. The ice is filtered with the CNI, but melts on the filter and is also removed with the CHC13 used as washing liquid. The CNI which is collected on a sintered glass funnel is washed 3x with CHC13 (1 Sml at Oo) and freed from last traces of solvent by being placed on a watch glass and exposed to the atmosphere in a good fume cupboard at room temp for Ih to give colourless needles (ca 4.5g), m 146-147O (sealed capillary totally immersed in the oil bath). The yield depends slightly on the rapidity of the operation, in this way loss by sublimation can be minimised. If desired, it can be sublimed under reduced pressure at temps at which CNI is

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Front MatterTable of Contents4. Purification of Inorganic and Metal-Organic ChemicalsAcetarsol to Arsenic TrichlorideArsenic Triiodide to Cyanogen IodideDecaborane to Lithium NitriteLithium Picrate to Rhodium (II) ChlorideRubidium Bromide to Sulphur DichlorideSulphur Dioxide to Zirconyl Chloride

Index