nomenclature of aliphatic/acyclic...
TRANSCRIPT
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Nomenclature of Aliphatic/Acyclic compounds
Line-Angle Formula (Skeletal Structure or Stick Figure):Very handy for writing organic structures, mostly for cyclic compoounds. Carbon atoms are assumed to bepresent wherever two lines meet or a line begins or ends. N, O, X, S (heteroatoms) are shown while C, H arenot shown. H is shown onto a heteroatom.
NH
O
OH
= H3C
NH
CH
CH
CH3C
CH3
CH3
CH3
CH
C
CH3
O
OH
AlkanesRule: Longest continuous carbon chain bearing maximum number of branches, numbered in the direction
in which any alkyl branch is met first (Lowest Set of Locant Rules). Name of alkyl branches written first withalphabetic order followed by Word Root + ane(primary suffix). The first letter of the complex branch isconsidered for alphabetic ordering. For simple branch the multiplying prefixes di-, tri-, tetra- are not consideredfor alphabetic ordring. Complex branches are multiplied with the prefix bis, tris, tetrakis, pentakis etc. Locantsare separated by commas and no space in between branches and parent alkane. If the set of locants is samefrom both side, then the alphabetically senior branch gets the lower locant.
branches + alk + aneExamples:Lower Set of Locants Rule:
H3CCH
CHCH2
CH3
CH
CH3
CH2
CH2
CH3
CH2
CH3
1
2
3
4
5
6
7
8H3C
CH
CHCH2
CH3
CH
CH3
CH2
CH2
CH3
CH2
CH3
1
2
3
4
5
6
7
8
4-ethyl-6,7-dimethyloctane(wrong) 5-ethyl-2,3-dimethyloctane(correct)
H3CCH2
CHCH
CH2
CH2
CH2
CH2
CHCH3
CH3
CH3
CH3
1
2 4
3 5
6
7
8
9
10
1
2
3
4
5
6
7
8
9
10
3,4,9-trimethyldecane (wrong) (not lower set: begininng with 3)2,7,8-trimethyldecane (correct) (Lower set: beginning with 2)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Same Set of Locants: Alphabetic Serniority:
1
2
3
4
5
6
H3C
CH2
CHCH
CH2
CH3
CH3
CH2CH3
1'
2'
3'4'
5'
6'
3-methyl-4-ethylhexane (wrong)
3-ethyl-4-methylhexan (correct)
Branching Rule:
H3CCH
CHCH2
CH3
CH
CH3
CH2
CH
CH3
CH3
1
2
3
4
5
67
CH3
(wrong)
H3CCH
CHCH2
CH3
CH
CH3
CH2
CH
CH3
CH3
1
2
3
4
5
6
7
CH3
(correct)
2,3-dimethyl-5-propan-2-ylheptane(wrong) 5-ethyl-2,3,6-trimethylheptane(correct)
The first one violates the branching rule. In 2nd one, the longest chain has largest number branches attached to it.
C HC H
C HCH
C H
C H 3
CH 3 CH 2
C H 3
C H 3
C H 3CH
H 3 C
H 3 C
CH3 C C H 3
CH 3
1
2
3
4
5
67
8
1 '
2 '
7 '
8 '
6-ethyl-2,2,4,5-tetramethyl-3,7-bis(propan-2-yl)octane
N.B: propan-2-yl is a complex branch to be discussed below.
Line Structure of Alkanes:
=
1
2
34
56
7
8CH3
CH2
CHCH
CH
CHCH2
CH3
CHCH3
H3C
CH2CH3
CH3
CH3
3,4-diethyl-2,5,6-trimethyloctane
SAQ I. 1: Give the IUPAC names of the following:
(i) H3C
CH
CH
CH2
CH3
CH3
CH3
(ii)
H3C CH
CH2
CH3
CH2 CH3
(iii) H3C C
CH CH3
CH3
CH2 CH3
CH3
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(iv)CH2
CH
CH2
CH
CH
H3CCH3
H3CCH3
CH2
CH3
(v) H3C C
CH3
CH3
CH3
(vi)H3C C C CH3
CH3
CH3
CH3
CH3
(vii) (viii)
SAQ I.2: Give the structural formula of the following compounds.
(i)2,3-dimethylpentane (ii)3-methylhexane (iii)2,2,4-trimethylhexane(iv)2-methylpropane
SAQ I.3: Some incorrect names are given. Write the structure of alkanes from them. Also give the correctnames.
(i)3-methylbutane (ii)2-ethylpropane (iii)4,5-dimethylhexane
Naming a complex branch:Latest Rule: Numbering made from one terminal to the other giving lower locant to -yl. When locant of -yl is 1,then the suffix ‘ane’ is replaced by ‘yl’ and the loacnt 1 is dropped. For example, propyl, butyl, etc instead ofprop-1-yl, but-1-yl.Simple alkyl groups like methyl, ethyl, propyl, butyl in which the locant of -yl is 1 are called simple branches.All other alkyl branches containing subbranches of simple alkyl groups like 2-methylpropyl or having locant of-yl other than 1 like propan-2-yl etc. are considered as complex branches. The first letter of the complexbranches is considered for alphabetic numbering which includes di-, tri-etc. Such branches are multiplied bythe prefixes bis, tris, tetrakis etc.When locant of ‘yl’ is not 1, then letter ‘e’ of ‘ane’ is replaced by ‘yl’,with the locant of ‘yl’ prefixing it. Forexample propan-2-yl etc.
3
CH3 CH
CH3
propan-2-yl
CH3 CH2 CH2
propyl
2
1
3 2 1
CH3 CH2 CH
CH3
4 3 2
1
butan-2-yl
CH3 CH2 CH2 CH2
butyl
34 2 1
CH3 C
CH3
CH3
32
1
2-methylpropan-2-yl
CH3 CH
CH3
CH2
3 2 1
2-methylpropyl
CH3 C
CH3
CH3
CH2
32 1
2,2-dimethylpropyl
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Old Rule:The carbon atom of the alkyl branch directly bonded to the principal carbon chain is numbered 1’ to find thelongest chain. Ultimately prime over the locant is dropped once it is put insidie parenthesis.
CH3 CH
CH3
1'2'CH2 CH
CH3
CH31'2'3'
2' 1'CH3 C
CH3
CH3
1-methylethyl 1-methylpropyl 1,1-dimethylethylisopropyl(propan-2-yl) sec-butyl(butan-2-yl) tert-butyl(2-methylpropan-2-yl)
3'CH3 CH
CH3
CH21'2'
3' 2' 1'CH3 C
CH3
CH2
CH3
2- methylpropyl 2,2-dimethylpropylisobutyl neopentyl
2-methylpropyl and 2,2-dimethylpropyl remain the same for both old and new conventions.
N.B: Many text books still use the old convention of naming a complex alkyl branch(1,1-dimethylethyl). Thenames like isobutyl, isopropyl, sec-butyl, tert-butyl, neopentyl are also used in some texts in IUPAC naming.So the student should not take much critically on this aspect. Remember that a structure can have more thanone IUPAC names out of which one is PIN(Preferred IUPAC Name) as per the latest conventions but onename can have a unique structure.Two branches having same initial words:When two groups have same initial words(or letters), the longer branch gets the higher locant. Beween
methyl and methylpropyl the former gets a lower locant.
3
42
1 5 6 7 8
9
10
11
12
3'2'
1'
1'2'
3'
6-methyl-8-(2-methylpropan-2-yl)-5-(2-methylpropyl)dodecane (latest)8-(1,1-dimethylethyl)-6-methyl-5-(2-methylpropyl)dodecane (old)8-(tert-butyl)-5-isobutyl-6-methyldodecane (old)
If you write according to old system, then for complex branch the prefixes di-, tri- are considered for alphabeticordering as in the new convention. Using the common names of the alkyl groups, the prefix tert- and sec- are notconsidered while the prefixes iso and neo are considered for alphabetic ordering.
3
42
1 5 6 7 8
9
10
11
12
3'
2'
1'
1'
2'
3'
6,6-bis(2,2-dimethylpropyl)dodecane
A complex branch has to be multiplied with the prefixes bis, tris etc. (not di, tri etc.)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
SHORT REPRESENTATIONS OF SOME COMMON ALKYL GROUPS:The following abbreviations are used for the alkyl groups written against their names.
methyl Me isobutyl i-Buethyl Et sec-butyl s-Bun-propyl n-Pr tert-butyl t-Buisopropyl i-Pr n-butyl n-Bu
SAQ I.4: Give the IUPAC names of the following compounds shown in line drawings.
(i) (ii)
(iii) (iv)
(v) (vi)
(vii) (viii)
(Rule for naming compound (viii): When two or more longest chains containing same number of branchesand same set of locants for the branches compete with each other, IUPAC recommends that thelongest chain which contains greatest number of carbon atoms in the branches is correct.
(ix) (ix) (x)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(xi) (xii)
(xiii)
SAQ I.5: Draw the line structures for the following molecules.
(i) 5-(2-methylpropy)dodecane (ii) 4-(propan-2-yl)-4-propylnonane(iii) 5-(butan-2-yl)-5-(propan-2-yl)decane (iv) 4,4-bis-(2-methylpropan-2-yl)heptane(v) 3-ethyl-6-(5-methylhexan-3-yl)-8-(propan-2-yl)undecane
Answers to SAQs
SAQ I.1 (i) 2,3-dimethylpentane(ii)3-methylpentane
(iii) 3
2
H3C C
CH CH3
CH3
CH2 CH3
CH31
4
5
3,3,4-trimethylpentane(wrong); the set of locants =3,3,4 which is higher
2,3,3-tripmethylpentane(correct) , The set of locants 2,3,3 is lower and is correct..
(iv) 3 5
6
71
2
4CH2
CH
CH2
CH
CH
H3CCH3
H3CCH3
CH2
CH3
(correct); 3 5
67
12
4CH2
CH
CH2
CH
CH
H3CCH3
H3CCH3
CH2
CH3
(wrong)
The second one is violating the branching rule. In the first, there are more number of branches attachedto the main chain. Count for yourself to verify.
Name: 3-ethyl-2,5-dimethylheptane.
The reverse direction of numbering would have given a higher set of locants: 5-ethyl-3,6-dimethylheptanewhich is wrong.
(v)
1 2 3
H3C C
CH3
CH3
CH3
; 2,2-dimethylpropane (same name if we reverse the numbering)
(vi)
1 2 3 4
H3C C C CH3
CH3
CH3
CH3
CH3
; 2,2,3,3-tetramethylbutane(same name on reverse numbering)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(vii) CH39
8
7
6
5
4
3
2
CH31
CH3
CH3
; 5-methyl-4-propylnonane (reverse numbering would have given the
set of locants 5,6 which is higher)
(viii) 5-ethyl-6,7-dimethyl-4-propyldecane
(The set of locants are same on either side. Hence lowest locant is given to alphabetically seniormost branchethyl by numbering from left to right).
SAQ.I. 2: While writing the structure of a compound from its name, first look to the word root of the parentalkane. In this case it is alk(e.g pent-, hex-, but- etc.). First draw a carbon chain containing the requirednumber of carbon atoms in straight chain. Let us take the first bit.
(i) The parent alkane is pentane. So let us first draw: C-C-C-C-C. Then number them from one end to theother end. Attach the substituents(branches) at the appropriate carbon atoms.
C C C C C
CH3 CH3
1 2 3 4 5
Then attach the required number of hydrogen atoms to each carbon atom of the main chain bearing inmind that the valency of carbon is 4.
CH3 CH CH CH2 CH3
CH3 CH3
1 2 3 4 5
(ii)CH3 CH2 CH CH2 CH2
CH3
CH3
2 3 4 5 6
(iii) CH3 C CH2 CH CH2 CH3
CH3
CH3
CH3
1 2 3 4 5 6
(iv) CH3 CH CH3
CH3
1 2 3
SAQ I. 3:
(i)CH3 CH2 CH CH3
CH3
1234
(2-methylbutane) (ii)
CH3 CH CH3
CH2
CH3
1 2
3
4(2-methylbutane)
(iii) CH3 CH2 CH CH CH CH3
CH3 CH3
123456
(2,3-dimethylhexane)
SAQ I.4:
(i) 4-ethyl-2-methyl-5,6-dipropylnonane
(ii) 3,6,8-triethyl-2,4-dimethyl-6-propylundecane
(iii) 5-(pentan-3-yl)decane (PIN); 5-(1-ethylpropyl)decane
(iv) 6-(3-methylbutyl)-5-(2-methylpropyl)undecane
(v) 2,3,5-trimethyl-4-propylheptane
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(vi) 2,5-dimethyl-4-(2-methylpropyl)heptane
(vii) 7-(2-methylhexan-2-yl)-7- (2-methylpentan-2-yl)tridecane (PIN)
OR 7-(1,1-dimethylbutyl)-7-(1,1-dimethylpentyl)tridecane
(viii) 7,7-bis(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyltridecane
(ix) 6-ethyl-2,4-dimethyl-5-(2-methylpropyl)-3-(propan-2-yl)octane (PIN)
OR 6-ethyl-2,4-dimethyl-3-(1-methylethyl)-5-(2-methylpropyl)octane
(x) 2,3-dimethyl-5-(propan-2-yl)octane(PIN) OR 2,3-dimethyl-5-(1-methlethyl)octane
(xi) 3,6-dimethyl-5-(3-methylbutan-2-yl)-7-(propan-2-yl)decane (PIN)
5-(1,2-dimethylpropyl)-3,6-dimethyl-7-(1-methlethyl)decane
(xii) 4-(2,2-dimethylpropyl)-9-ethyl-2,2-dimethyl-6,6-bis(2-methylpropan-2-yl)undecane(PIN)
6,6-bis(1,1-dimethylethyl)-4-(2,2-dimethylpropyl)-9-ethyl-2,2-dimethylundecane
(xiii) 6-methyl-5-(3-methylbutan-2-yl)decane(PIN) OR 5-(1,2-dimethylpropyl)-6-methyldecane
SAQ I.5:
(i)
CH3
CH3
CH3
CH3
(ii)
CH3
CH3
CH3CH3
CH3
(iii) CH3
CH3
CH3 CH3
CH3CH3
(iv) CH3 CH3
CH3CH3
CH3
CH3
CH3
CH3
(v)CH 3
C H 3
CH 3 C H 3
CH 3
C H 3
C H 3
C H 3
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
ALKENES & ALKYNESRulesOld:
C C / C C should be a part of principal carbon chain even if it may not be the longest chain.
Locant of ‘ene’/ ‘yne’ should be least. In case of tally, the LSL(lower set of locants) rule for branches come intoforce.
Branches + Word Root + primary suffix(ene/yne)
CH2
CCH
CH2
H3C CH2
CH3
CH3
1
2
3
4
5
1
2
3
4
5
(2-ethyl-3-methylpent-1-ene)
(not 4-ethyl-3-methylpent-4-ene)
H3CCH
CH
CH
CH2
CH3
CH31
2
3
4
5
6
1
2
3
4
5
6
(2-methylhex-3-ene)
(not 5-methylhex-3-ene
HC C C CH3
CH3
CH3
1 2 3 4
3,3-dimethylbut-1-yne (not 2,2-dimethylbut-3-yne)
12345
6
C CCH
CH3
C
CH3
CH3
CH3
CH3
2,2,5-trimethylhex-3-yneNOT 2,5,5-trimethylhex-3-yne
SAQ Write the IUPAC names from the following line structures.
(i) (ii)
Answer:
(i) 6-(butan-2-yl)-3-(propan-2-yl)-2,2,7-trimethylnon-4-yne
(ii) 3-ethyl-8-methyldec-5-yne(ethyl gets precedence over methyl due to alphabetical seniority ofthe former)
NEW:
Longest continuous carbon chain to be taken as parent hydrocarbon. This may or may not include C C /
C C . If C C / C C is not included, the parent becomes alkane. In such case, the branch containing
C C / C C are written along with other alkyl branch in alphabetic order.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Naming branch containing C C / C C :Monvalent alkenyl and alkynyl group:The letter ‘e’ of ene/yne is replaced by ‘yl’. It becomes alkenyl or alkynyl. Note that ‘en/yn’ has its locant and‘yl’ also has its locant. If the locant of ‘yl’ is 1, then it is dropped. According to new convention, the branch isnumbered from one terminal to another like a complex alkyl group. However, the old rule is still followed by sometext books in that the carbon atom bonded to the longest chain is numbered 1. See the following examples.
1
prop-1-en-1-yl
3 2 1
CH3 CH CHprop-2-en-1-yl or allyl
3 12CH2 CH CH2
ethenyl or vinylCH2 CH
or prop-2-enyl or prop-1-enyl
CH3 C
CH2
3 2
1
prop-1-en-2-yl
CH3 CH CH CH
CH3
5 4 3 2
1
but-3-en-2-yl
(1-methylethenyl) (1-methylbut-2-enyl)
HC C HC C CH2 H3C C C
ethynyl prop-2-yn-1-ylor prop-2-ynyl
prop-1-yn-1-ylor prop-1-ynyl
Bivalent alkylidene group:If =C- is directly bonded to the longest chain, then the group is bivalent. In that case, a suffix ‘idene’ is to beused with the respective ‘alkyl’ group.
alkyl + idene = alkylidenealkyl - alkylidene
CH3- (methyl group) CH
2= (methylidene group)
CH3-CH
2-(ethyl) CH
3CH= (ethylidene)
CH3-CH
2-CH
2-(propyl) CH
3-CH
2-CH= (propylidene)
H3C
CH
H3C(propan-2-yl/isopropyl
H3C
C
H3C(propan-2-ylidene/isopropylidene)
Naming bivalent group contianing one more C C / C C :
alkenyl + idene = alkenylidene alkynyl + idene = Alkynylidene
CH CH CHH3C (but-2-enyl) CH CH CHH3C (but-2-enylidene)
CH C CH (prop-2-ynylidene)
SAQ : Write the names of the following groups.
(i)
H3C
CH
H3C
CH2 CH (ii)CH2 CH C
CH3
CHCH3
(iii) H3C C C CH
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(iv)H3C C
CH3
CH(v)
H3CCH
H3C
C C CH2 (vi) H2C C
CH3
CH CH2
CH3
(vii)CH2=C=
(viii) CH3CH(CH
3)CH(CH
3)CH= (ix) CH
3CH
2C(CH
3)=
Answer:
(i) 3-methylbutylidene (ii)2-methylpent-2-enylidene
(iii)but-2-ynylidene (iv)2-methylprop-1-enyl
(v)4-methylpent-2-ynyl (vi)2,3-dimethylbut-3-enyl
(vii)ethenylidene(vinylidene) (viii) 2,3-dimethylbutylidene
(ix) butan-2-ylidene
Naming Alkenes and Alkynes according new rule:
CH31
2
3
4
5
6
7
8
CH39
CH2
CH3CH39
8
7
6
5
4
3
2
1
2
CH3
CH31
2-methyl-7-methylidenenonane(new name) 5-(prop-2-ynyl)nonane( new name)2-ethyl-7-methyloct-1-ene(old name) 4-butyloct-1-yne(old name)
SAQ : Write the names of names of the following alkenes and alkynes on the basis of the new rules.Compare the names with those obtained by using old rules.
(i) CH3
CH3
CH3
CH3
CH3
(ii)CH3
CH3
CH3
CH3
CH3
CH3
(iii)
CH3
CH3
CH3CH
Answer:(i) 3,4-diethyl-5-methylhept-2-ene(same according both the rules as the C=C bond is included in
the longest chain)
(ii) 4-ethyl-2,7-dimethyl-5-propylidenenonane(new);
5-ethyl-7-methyl-4-(2-methylbutyl)oct-3-ene(old)
(iii) 3-ethyl-5-ethynyloctane(new); 5-ethyl-3-propylhept-1-yne(old)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Haloalkanes(Alkyl Halides)Rule:The halo group(-X) may or may not be directly bonded to the longest carbon chain. If it is not directly bonded,then it is part of a complex alkyl group with a halo subbranch. The naming is done just like any alkane. Halobearing group competes with other alkyl groups for alphabetical seniority.
H3C CH CH CH2 CH3
CH3 Br
1 2 3 4 5
: 3-bromo-2-methylpentane(not 3-bromo-4-methylpentane)
CH37
6
CH3
5
4
3 CH3
2
CH3 CH31
Br
CH3
4-(2-bromoethyl)-3-ethyl-2,5,6-trimethylheptane
In the above example, Br- is a part of a complex group bromoethyl.SAQ : Give the IUPAC names from the following line structures
(i) Cl
(ii)
I
(iii)CH3 CH3
Cl BrCH3
Asnwer:(i) 4-(butan-2-yl)-3-chloro-5-methylheptane (ii)4-ethyl-5-iodomethyl-2-methylheptane(iii) 2-bromo-6-chloro-4-methylheptane
Functional Groups having Secondary Suffixes:(Naming multifunctional compounds)
The following table gives the functional groups and their suffixes which are used after primary suffix.
Branches(Prefixes)+Word Root + primary suffix + secondary suffix
Word Root: meth(1), eth(2), prop(3), but(4), pent(5), hex(6), hept(7), oct(8), non(9), dec(10),undec(11), dodec(12), tridec(13), tetradec(14), pentadec(15), hexadec(16), heptadec(17),..icos(20), henicos(21), docos(22), tricos(23), tetracos(24), pentacos(25).... triacont(30),hentriacont(31), dotriacont(32), tritriacont(33), tetratriacont(34)...... tetracont(40),hentetracont(41),dotetracont(42), tritetracont(43)..........pentacont(50),henpentacont(51),dopentacont(52)......., hexacont(60), henhexacont(61), dohexacont(62).....,heptacont(70), henheptacont(71), doheptacont(72)...... octacont(80), henoctacont(81),dooctacont(82)....... nonacont(90), hennonacont(91), dononacont(92)...... hect(100), henihect(101),dohect(102), trihect(103), tetrahect(104).....decahect(110), undecahect(111),dodecahect(112)........icosahect(120).....
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Primary suffix : ane/ene/yne
1. If there will be at least one C=C or C C , then primary suffix ‘ane’ is not used. In stead ‘ene’ or
‘yne’ is used. If there are more than one C=C or C C , then di-, tri- etc. are used as prefix to ‘ene’, ‘yne’.
In such case, the letter ‘a’ is suffixed to the Word Root (alk) to maka it alka (eg buta, penta, hexa etc.). Forexample buta-1,3-diene(not but-1,3-diene).
2. C=C or C C can be used as primary suffix as ‘ene’ or ‘yne’ along with the secondary suffix of the
seniormost functional groups. They can also be used in a branch with the name alkenyl, alkynyl, alkylidene,alkenylidene or alkynylidene etc.3. The following table gives the functional groups with decreasing priority order for which secondary suffixis used. These are called Type C groups which can both be used as suffix or as prefix(branches).
Type C functional Groups:Name of group structure prefix suffix
carboxylic acid C
O
OH carboxy -oic acid(carboxylic acid)
sulfonic acid -SO3H sulfo sulfonic acid
acid anhydride C
O
O C
O- -oic anhydride
ester C
O
OR' alkoxycarbonyl -oate(carboxylate)
acid halide C
O
X halocarbonyl-oyl halide(carbonyl halide)
acid amide C
O
NH2aminocarbonyl
-amide(carboxamide)
nitrile C N cyano -nitrile(carbonitrile)
aldehyde C
O
Hoxo
(formyl)-al
(carbaldehyde)
ketone C
Ooxo -one
alcohol -OH hydroxy -olthiol -SH sulfanyl/mercapto -thiolamines -NH
2/-NHR/-NR
2amino -amine
________________________________________________________________________________
Deletion of ‘e’: If the secondary suffix begins with any vowel such as ‘a, y, i, o, u’ then the letter ‘e’ tobe deleted from prmary suffix ane/ene/yne. For example butanol, pentanone, but pentanenitrile.
(NB: For acquainting with the IUPAC naming compounds containing single functional group,please refer e-Concepts in Chemistry for Junior Level: Nomenclature Chapter-II)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Rules:
* The LONGEST carbon chain bearing the highest priority functional (type C) group should also bearmaximum number of other type C groups. Such group(s) cannot be ignored or be excluded from the longest
chain. Such a chain may exclude C=C or C C if required, if they are not part of the LONGEST chain
containing maximum number of type C groups.
Conclusion: The longest chain bearing the highest priority group may or may not include other functional
groups or C=C/ C C . Betwen any typc C group and C=C/ C C , the former is preferred.
* The one having highest priority among such groups will make the secondary suffix. In other wordsthe parent compound will be named after this. Other such groups will be used as branches(prefixes). For-OH it is hydroxy, for (-C=O) it is oxo and so one. Look to the prefix column for this. The suffix nameswhich are written inside parenthesis below their respective first names are used only when such functionalgroup is outside the principal carbon chain. For example, if -COOH remains within the principal chain, i.ethe carboxyl carbon is counted as no. 1, then the secondary suffix ‘oic acid’ is used. If -COOH remainsoutside the carbon chain, then ‘carboxylic acid’ is used. As a prefix also if -CHO(aldehyde) group remainsoutside the carbon chain, then ‘formyl’ is used otherwise ‘oxo’ is used.
Groups which are used only as substitutents(Prefix): Type A groups
Such groups do not have any priority order. All such groups obey LSL rule.
Name of the group General formulaalkyl R-alkoxy RO-alkylsulfanyl(alkylthio) RS-halo X-nitro NO
2-
alkenyl R CH CH
alkynyl R C C
phenyl C6H
5-
cycloalkyl cyclopropyl, cyclobutyl etc.
(Note that C=C and C C are called Type B functional groups which are used as primary suffix(ene/yne)
* Since -COOH and derivatives of -COOH and -CHO are terminal functional groups, the one whichhas the highest priority among them always gets no. 1 locant.* When –CN is a lower priority group in a molecule, it is never taken inside the principal carbon chain.It is always used as prifix(cyano). Cyanide carbon is never counted in such case.
* In polyene/enynes C=C and C C enjoy the same priority. However in case of tally, ‘ene’ gets
the precedence.
CH38
7
6
5
Cl
4
3
2
1
O
OH
OHO
O
CH3
N
5-chloro-2-cyano-4-hydroxy-7-methoxy-6-oxooct-3-en-1-oic acid OR
5-chloro-2-cyano-4-hydroxy-7-methoxy-6-oxooct-3-enoic acid
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(locant 1- for terminal functional groups appearing in secondary suffix is deleted).
H
5
O
4
3
2
1
O
O
OH
OH
Cl
CH3
ethyl 4-chloro-3-hydroxy-2-(hydroxymethyl)-5-oxopentanoate
(note that for aldehyde group, we used the prefix ‘oxo’ as it is a part of the carbon chain. For ketones toowe shall use ‘oxo’.
4
3
2
1
O
OH
O H
5
OH 6
NH2
6-amino-5-hydroxy-4-(2-oxoethyl)hexanoic acid
The longest chain containing more number of functional groups is chosen irrespective their priorities.
NH2
OOH
NH2
65 4 3 2
1
2-amino-5-methyl-6-oxohex-3-ynamide
6
5 4 3 2
NH2
1
O
OHO
NH2
O
H
2,6-diamino-5-formyl-6-oxohex-3-ynoic acid
In the 2nd case above, amide is senior to aldehyde, hence amide carbon was included in the principal chain.Since -CHO is now excluded from main chain, the prefix ‘formyl’ has been used. Note that for amide group,we used two suffixes, one for -C=O(oxo) and other other for -NH
2(amino).
functional group two prefixes usedamide both amino and oxo (not aminocarbonyl)acid chloride both chloro and oxo (not chlorocarbonyl)ester both alkoxy and oxo (not alkoxycarbonyl)
OH
O
Cl6
5 43
2
1
2-ethyl-4-formylhexanoyl chloride
OH
O
O
CH3O
4
32
1
4-methoxy-2-methyl-4-oxobutanoic acid
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
OCH3
OSO3H
4-methoxy-3-methyl-4-oxobutane-2-sulfonic acid
43
2
1 CH31 2
3
O
4
5
6
CH37
OHBrCl
4-bromo-2-chloro-6-hydroxyhept-5-en-3-one
H2N OH
3-aminopropan-1-ol(not 3-hydroxypropan-1-amine
12
3
I
CN OH1
23
4
1'
2'
3'4'5
6
2-(3-hydroxybutan-2-yl)-3-iodo-4-methylhexanenitrile
2-chloro-5-bromohexane(wrong)2-bromo-5-chlorohexane
Br
Cl CH38
7
6
5
4
3
2
1
OH
OCH2CH3
7-methyl-5-methylideneoctanoic acidold: 5-(2-methylpropyl)hex-5-enoic acid)
CH36
5
4
3
2
1
O CH3
CH3O
CH2
OH
7
6
5
4
3
2
1
O
OH
CH2
propan-2-yl 2-(prop-2-enylidene)hex-4-enoate 7-hydroxy-4-methylideneheptanoic acid old: 1-methylethyl 2-(but-2-enyl)penta-2,4-dienoate old: 4-(3-hydroxypropyl)pent-4-enoic acid
CH36
5
4
3
2
1
O
OH
COOEt
4-(ethoxycarbonyl)hexanoic acid
CH3 C
O
CH
CHO
C C CH CH2 CH3
CN23456
7
2-ethyl-5-formyl-6-oxohept-3-ynenitrile
1
C
O
OHN
2 13
4
4-cyano-2-methylbutanoic acidCN O
O12
3
45
6
sec-butyl 5-cyano-2-methylpentanoate
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
2
3
4
1
NCO
OH 2
34
5
1CN COOEt
4-cyano-2-methylbutanoic acid Ethyl 4-cyano-2-ethyl-3-methylpentanoate
O
CHCH3
CH3
COOEt
CHOC
O
EtO OH
O
123
45
6
7
ethyl 6-methyl-7-oxo-4-(propan-2-yloxy)hept-4-enoate 7-ethoxy-7-oxoheptanoic acid
C
O
EtO OH
O
123
45
6
7 8
C
O
O
CO NH2
CH
CH3
CH3
1
2
3
4
56
78
6-(ethoxycarbonyl)oct-7-enoic acid propan-2-yl 6-(aminocarbonyl)octanoate
Polyenes/Polyyenes/enyes:
In this case, longest chain is the key. That chain can bear C=C, C C , then its preferred. Such longest
chain should bear maximum number of multple bonds, but not at the cost of chain length.
6
5
43
21
3-methylhex a-1,4-diene
110
98
76 5
4
32
5-ethyl-7,9-dimethylundeca-4,6-diene
11
76
54
3
2
1
4-isopropyl-6-methyl-3-propylhept-5-en-1-yne
1
23
4
but-1-en-3-yne
1
2
3
4
56
hexa-1,3-dien-5-yne
(I) (II)
(III)(IV) (V)
[Please read 4-(propan-2yl) for 4-isopropyl in (III) of the above structures and put it after 6-methyl. Isopropylcan be used but it is now not PIN].
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
234
567 1
8
9
23
45
6
7
1
6-ethyl-3,7-dimethyl-4-methylidenenon-2-ene 4-(ethenyl)hep-5-en-1-yneold: 2-(2-ethyl-3-methylpentyl)-3-methylpenta-1,3-diene
(In the last structure ‘e’ has been deleted from ‘ene’ as ‘y’ is facing it. ‘en’ is always written first even thoughits locant is higher)
12
34
56
7
1'2'
3'
CH21
2 3
4 5
6 7
8 9 CH10
CH3
CH2
4-(prop-1-enyl)hepta-1,4-diene 7-ethenyl-5-ethylidenedec-1-en-9-yne
CH37
6
5 4
CH
CH2
3
2 CH31
CH3
CH2
4
5
6
7
8
CH39
3
2
CH31
CH
3-ethenyl-3-ethynyl-2-methylheptane 5-(prop-2-ynylidene)-4-vinylnona-2,7-dieneOld: 4-(2-methylpropyl)-4-propylpent-1-en-4-yne 4-(but-2-enyl)-5-ethenylocta-3,6-dien-1-yne
Compounds containg idential functional groups:In such case, the secondary suffix is prefixed with di-, tri- etc. For example, diol, trione, dial etc. In such casethe ‘e’ of primary suffix is not dropped.Rule: The principal chain should bear maximum number functional groups.
(glycerol)(ethylene glycol)
propane-1,2,3-trio
CH2 CH CH2
OH OHOH
5-bromohexane-2,4-diol
65
43
21
ethane-1,2-diol
CH2 CH2
OH OH
OH OH
Br
OH
OH1
23
4
2-butylbutane-1,4-dio
CH36
5
4
3 CH3
2
1
OH
OHOH
3-(1-hydroxyethyl)hexane-1,4-diol
CH31
2
3
4
5
6
7
CH38
NH2 CH3NH2
7-methyloctane-3,5-diamine
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
CH3
5
CH36
4
3
2CH31
OO
CH3
CH31 2
34
5 CH3
OO
67
89
CH310
O
3-ethyl-5-methylhexane-2,4-dione 5-(1-oxoethyl)decane-2,7-dione
H C
O
C
O
Hethanedial
(oxalaldehyde)
H C
O
CH2 C
O
Hpropanedial
(malonaldehyde)
H C
O
CH2 CH2 C
O
Hbutanedial
(succinaldehyde)
C C
O O
HO OHethanedioic acid
(oxalic acid)
HOOCCH2
COOH
propanedioic acid(malonic acid)
HOOC
CH2 CH2
COOH
butanedioic acid(succinic acid)
HOOC(CH2)3COOH
HOOC(CH2)4COOH
(pentanedioic acid/glutaric acid)
(hexanedioic acid/adipic acid)
5
43
2
1COOH COOH
2-ethyl-4-isopropylpentanedioic acid
5 213
4
OO
OO
diisopropyl 2-methylpentanedioate
OH2N
NH2O
1
23
4
5
6
2-ethyl-5-methylhexanediamide
(Please read di(propan-2-yl) for diisoprpyl)
O
O
O
CH3 CH3
O
CH3
CH3
1-ethyl 5-isopropyl 2-methylpentanedioate
21 3
45Cl
O
Cl
O
3-ethyl-2-methylpentanedioyl dichloride
NC
CN12
34
5
6
2,4-dimethylhexanedinitrile
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Compound containing 3 or more identical carbon-bearing terminal functional groups :Case-I If the 3rd group is directly bonded to the principal chain containing two groups, then all the three arenot included for the parent carbon chain. In such case, the following suffixes are used after alkane.
alkane tricarboxylic acid(acid); trialkyl alkanetricarboxylate(ester);alkane tricarbaldehyde(aldehyde); alkanetricarbonitrile(nitrile);alkane tricarboxamide(amide); tricarbonyl trichloride(acid chloride)
5
213
4
OHO
O
OH
OOH
butane-1,1,2-tricarboxylic acid
O
OCH2CH3
O
CH3CH2O
OOCH2CH3
12
3
4
triethyl pentane-1,2,3-tricarboxylate
O 3
2
1
O
H
H
O H
propane-1,2,3-tricarbaldehyde
CH32
3
4
5
CH36
CN1
CN
CN
2-methylhexane-1,3,4-tricarbonitrile
1
O
Cl
O
Cl
O Cl
methanetricarbonyl trichloride
Case-II: If the 3rd group is not directly bonded to the carbon chain, then two groups in the chain are includedin the principal chain, the third becomes subbranch of an alkyl branch eg. carboxymethyl, amioncarcarbonylmethyletc.
HOOCCOOH
COOH
1
2
3
4
5
6
7
4-carboxymethylheptanedioic acid
CN CN
CN
12
34
5
3-cyanomethyl-2-methylpentanedinitrile
CH3CH2O OC
diethyl 3-methyl-5-(3-ethoxy-3-oxopropyl)octanedioate
3'
2'1'
1
23
45
6
78
COOCH2CH3
COOCH2CH32'
1'
2-methyl-3-(2-oxoethyl)hexanedial
1
23
4
56OHCCHO
CHO
SAQ: Give the IUPAC names of the following compounds from their line structures.
(i)OH
(ii) COOH
(iii) OOH
(iv)
NH2
OH
Cl
Br
(v) CN
O
H (vi)
O
OH
SO 3 H
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(vii) CH3
COOHO
O
CH3
CH3
CH3
CHO
CH3
(viii) Cl
O
SO3H
(ix)
OH
(x) H
S NH2
(xi)
SH
CH3
OH
(xii)
CH3
S CH3
CH3
OH
CH3
(xiii)
CH3
O
CH3
O
OH
(xiv) CH3
CH3
OCH3 CH3
CH3
(xv)
O
OH
CHO
Asnwer:(i) pent-4-en-2-ol (ii) 2-methylhex-3-ynoic acid
(iii) 5-hydroxyhexan-3-one (iv)3-amino-2-bromo-5-chloroheptan-4-ol
(v) 2-methyl-5-oxopentanenitrile (vi)2-methyl-3-sulfobutanoic acid
(vii) 7-tert-butoxy-6-formyl-3,5-dimethyl- 7-oxohept-4-enoic acid
(viii) 6-chloro-4-methyl-6-oxohex-1-yne-3-sulfonic acid
(ix) 2-(prop-1-enyl)hexan-1-ol(new); 2-butylpent-3-en-1-ol(old)
(x) 3-aminopropane-1-thiol
(xi) 4-sulfanylbutan-2-ol (4-mercaptobutan-2-ol) (xii)7-(propan-2-ylthio)octan-4-ol
(xiii) 7-oxo-4-(prop-1-enyl)octanoic acid(new);4-(3-oxobutyl)hept-5-enoic acid(old);
(xiv)3-(but-1-enyl)-6-ethyl-7-methyloctan-2-one(new); 3-(3-ethyl-4-methylpentyl) hept-4-en-2-one(old) ;
(xv) 4-formyl-5-phenylhept-2-enoic acid
SAQ: Write the IUPAC names of the following compounds.
(i)
CH3
CH3
CH3
CH
CH3
CH3
(ii) CH2
CH2
CH2
CH3
CH
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(iii) CH2
CH
CH3
CH2CH3
CH3
(iv)
CH3 CH3
CH3
CH3
CH2
CH3
(v)CH3
CH3
CH3
CH3
CH2
Answer:
(i) 4-ethynyl-2-methyl-5-(pent-2-en-2-yl)undec-2-en-8-yne(ii) 3-ethynyl-4-methyl-5-methyidenehepta-1,6-diene(iii) 3-ethynyl-4-(prop-1-en-2-yl)-6-methyldeca-1,3,6-trien-8-yne(iv) 4-ethenyl-6-methyl-7-(propan-2-ylidene)undeca-2,5,9-triene(v) 6-ethyl-4-methylidene-5-(prop-1-enyl)dodeca-7,9-dien-2-yne
SAQ: Write the IUPAC names of the following.
(i)
H2N NH2
OO
O
NH2 (ii)
O
NH2
O
H
O
HO
(iii) O O
OOCH3
NH2NH2
(iv) O O
ONH2
NH2NH2
(v) O O
O
NH 2
OH
(vi) OO
O
OO CH3
OHCl
(vii)
O H
O H
O H
(viii)
O O O
CH3
CH3
CH3
(ix) NH
NH
CH3
CH3
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(x)CH3
CHO
CHO
CHO
(xi)
O
C l
O
C l
O
C l
(xii) O
O O
O
CH3
CH3CH3
CH3
Answer:(i) 3-(2-amino-2-oxoethyl)-2,3-dimethylpentanediamide(ii) 3-(2-amino-2-oxoethyl)-6-oxohexanoic acid)(iii) methyl 7-amino-2-(3-amino-3-oxopropyl)-7-oxoheptanoate(iv) heptane-1,3,7-tricarboxamide(v) 4-(aminocarbonyl)-7-oxoheptanoic acid(vi) 9-chloro-5-formyl-6-(methoxycarbonyl)-9-oxononanoic acid(vii) propane-1,2,3-triol(glycerol)(viii) 2-methylnonane-3,5,7-trione(ix) N,N’-dimethylbutane-1,4-diamine(x) pentane-1,1,3-tricarbaldehyde(xi) 3-(2-chloro-2-oxoethyl)hexanedioyl dichloride(xii) 5-ethyl 1-(propan-2-yl) 2-methylpentanedioate
(When two alkoxy(OR’) parts of diester are different, each alkyl group is prefixed with the locant of carboxylcarbon to which the alkoxy group is attached)
SAQ: Draw the structures of the following.
(i) ethyl 6-cyano-4-methyl-3-methylidenehepta-4,6-dienoate(ii) methanetricarbaldehyde(iii) 2,3,4,5,6-pentahydroxyhexanal(iv) 3-ethenyl-2,3,6-trimethylocta-1,6-dien-4-yne(v) 3-(2-amino-2-oxoethyl)pentanediamide
Answer:
(i) CH27
6
5
4
3
2
1
O
O CH3
CN CH3
CH2
(ii)CHO
OHC
OHC
(iii)
O
H
O H
OH
O H
O H
OH(iv)
CH38
7
6 5 4 3 2
CH21
CH2
CH3CH3CH3
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Naming Bivalent and Multivalent Radicals:
Divalent radicals using the suffix ‘idene’ has been already discussed. That is case when one H atom is removedfrom a monovalent alkyl group. Similarly when two H atoms are removed from a monovalent alkyl group, itbecomes a trivalent radical.Trivalent radical: yl of alkyl is suffixed with ‘idyne’.
CH : methyl+idyne = methylidyne CH3 C : ethyl + idyne = ethylidyne
Note that these radicals cannot attach with any carbon chain. However such groups are used in complexcompounds of metals ions as ligands.Bivalent radicals obtained by removing H atom from the two terminal carbon atoms(two monovalent radicalsin one species) of a normal alkane(unbranched)
The suffix ‘ene’ is used after polymethyl : polymethyl+ene = polymethylene
CH2
CH2 tetramethyl+ene = tetramethylene (butylene)
–CH2–CH
2– : ethyl + ene = ethylene
Similarly hexamethylene, pentamethylene etc. These namings are used in trivial systems, eg.(1) hexamethylene diamine(for hexane-1,6-diamine) (2) ethylene dichloride(1,2-dichloroethane)Multivalent radicals on two terminals :
alkane + diyl + idene (if both the terminals are C=)
alkane + diyl + idyne (if both terminasl are C )
alkan+yl+ylidene (if one is C– and other is C=)
CHCH
butane+diyl+idene = butanediylidene
CHCH
butane + diyl + idyne = butanediylidyne
CHCH
butan-1-yl-4-ylidene
Such groups(restricted to divalent on either side) can be used in naming compounds in trivial system egbutanediylidene diimine. However trivalent radicals on either side cannot be used often usually in organicstructures.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Naming of Alicyclic compounds:
cyclopropane cycloprpyl cyclobutane cyclobutyl cyclopentane cyclopentyl
cyclohexane cyclohexyl
Naming aliphatic compounds with cyclic branches:
O
O
Cl
O OH
5-cyclopropyl-4-oxoheptanoyl chloride 1-cyclobutyl-3-hydroxybutan-1-one
* If the cyclic ring is attached to one carbon atom or one functional group, then the naming should bedone as a cyclic compound. In other words, if the higher priority functional group is directly attached to thering, then it is named as a cyclic compound.* If the cyclic ring is attached to more than one carbon, then it can have two alternative names : (i) as analiphatic compound with cycloalkyl prefix or (ii) a cyclic compound with aliphatic prefix. The aliphatic name ispreferred(PIN)j in such case. See the following examples.
COOH CH2COOH
cyclobutane carboxylic acid 2-cyclopentylethanoic acid(aliphatic name)(not cyclobutylmethanoic acid) carboxymethylcyclopentane (cyclic name)
CH2CH2CH2HO
OH
OHCH2CH
1-[4-(3-hydroxypropyl)cyclohexyl]ethane-1,2-diol
3' 2'
1'4'3'' 2'' 1'' 12
3-cyclohexylbutanoic acid
12
34
CO O H
Only in case of the 1st compound, the cyclic name is preferred. In all the other three examples, the aliphaticnames are preferred as the functional group is not directly bonded to the ring.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Other logic for naming as valid for aliphatic compounds are also valid for ring compounds. After the highestpriority group, C=C is considered(not other functional group) for LSL rule.
2
3
1
4
6
5
OH
cyclohex-2-en-1-ol
2
3
1
4
6
5
OOH
CH3
6-methylcyclohex-2-ene-1-carboxylic acid
2
3
1
4
6
5
O
CH3
OH
4-hydroxy-2-methylcyclohexanone
6
5
1
4
2
3
OCH3
H
2-ethylcyclohexanecarbaldehyde
2
3
1
4
6
5
O
ONH2
5-oxocyclohex-2-ene-1-carboxamide
2
3
1
4
6
5
OCl
OH
6-hydroxycyclohex-3-ene-1-carbonyl chloride
6
5
1
4
2
3
OO
OH
CH3
O
methyl 2-hydroxy-5-oxocyclohexanecarboxylate
3
4
2
5
1
6
OH NH2
3-aminocyclohexanol
OH
2
1
2-ethylcyclohexanol(2-ethylcyclohexan-1-ol)
NH2
O
O NH2
2-(8-amino-8-oxooctyl)cyclohexanecarboxamide
COOHOH
cycloprop-2-ene-1-carboxylic acid 3-cyclobutylpropan-2-ol
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
CH3
OH
NH2
NH2
1-(2,4-diaminocyclohexyl)propan-1-ol
CH3
CHO 3-methylcyclohexane-1-carbaldehyde
NH2
CONH2
OH
2-aminocyclopentane-1-carboxamide cyclobut-2-en-1-ol
SAQ : Write the IUPAC names of the following.
(i)
CH3
OH (ii)
ONH2
O
O H (iii)
CH3
O
O
OH
(iv)
CH3
OH
(v)
OHC H 3
C H 3
CH 3
(vi)
CH3
COOH
OH
(vii)
CH3
CH3
CH3
NH2
(viii)
CH3
CH3
Answer:(i) 3-(6-methylcyclohex-1-enyl)propan-1-ol(ii) 3-[2-(aminocarbonyl)cyclohexyl]propanoic acid(iii) 4-(3-formylcyclopentyl)-2-methylbutanoic acid(iv) 1-cyclopentylethanol(v) 2-(2,3-dimethylbutyl)cyclobutanol(vi) 3-(5-hydroxycyclohex-2-enyl)-2-methylpropanoic acid(vii) 2-(2,2-dimethylbutyl)cyclopropanamine(viii) 1-ethyl-2-propylcyclohexane
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
AROMATIC COMPOUNDS:
Benzene(C6H
6): It is primarily the hybrid of the two resonating structures.(Refer Chemical Bond for details).
Benzene and its derivatives are aromatic compounds. Such compounds are unique in their behaviour. Theyare more stable and hence less reactive than their acyclic analogue hexa-1,3,5-triene apart from havingacceptable fragrance(aroma). The details of aromaticity will be discussed later in the chapter aromatichydrocarbons.
Resonating Structures
(Resonance Hybrid)
All the six positions of benzene are equivalent.
(C6H
5–) phenyl CH2 (benzyl)
Monosubstituted Benzene:
CH3Cl OH NO2
toluene(methylbenzene)
chlorobenzene phenol nitrobenzene
NH2
aniline(hydroxybenzene) (aminobenzene)
1 2
CHO COOH COCH3
benzaldehyde benzoic acid acetophenone(1-phenylethanon
CN COCl CONH2 COONa
benzonitrile benzoyl chloride benzamide sodium benzoate methylbenzonate
COOCH3
OCH3 O
methoxybenzene(anisole)
benzophenone(diphenylmethanone)
biphenyl
NO
(nitrosobenzene)CH2 Cl
chloromethylbenzen(benyl chloride)
e
CH Cl
Cl
dichloromethylbenzen(benzal chloride)
e
C Cl
Cl
Cltrichloromethylbenzen(benzotrichloride)
If the functional group is not directly bonded to the benzene ring, then the compound is named as aliphatic.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
OH
phenylmethanol
COOH
phenylacetic acid
OH
triphenylmethanol
CH2 OH
(benzyl alcoholphenylmethano
SAQ III.8: Write the IUPAC names of the following compounds.
CH2CH3 CHH3C CH3
COCH2CH3
I
OCHCH3 COOCH(CH3)2
(i) (ii) (iii) (iv) (v) (vi)
(vii)
Answer:(i) ethylbenzene (ii) isopropylbenzene(cumene)(iii) propiophenone(1-phenylpropan-1-one) (iv) ethoxybenzene(v) isopropylbenzoate (vi) iodobenzene(vii) 1,2,3-trimethylbutylbenzene
SAQ: Write the IUPAC names of the following.
(i)Cl
(ii)NH2
(iii) O
O
CH3
(iv)CN
(v)
CH3
CH3
CH3
CHO
Answer: (i) (chloromethyl)benzene(Cl is not a functional group) (ii) 1-phenylmethanamine(iii) methyl 2-phenylacetate(ethanoate) (iv) phenylacetonitrile(phenylethanenitrile)(v) 2,3-dimethyl-3-phenylbutanal
Disubstituted Benzene :
X
Y
X
Y
X
Y
12
11
2 2
3 3
43
4
5 55
6 6 6
4
1,2- or ortho 1,3- or meta 1,4- or para
There are three isomers for two substituents namely (i) ortho(1,2) (ii) meta(1,3) (iii) para(1,4). There twoequivalent ortho positions with resepct to a particular substitutent on either side of it. Similarly there are twoequivalent meta positions for group. But there is only one para position.
Naming:
Rules: Priority order among Type C groups are the same as for aliphatic compounds.
-COOH >-SO3H > -COOR’ > COCl > CONH
2 > -CN > -CHO > -COR > -OH > -NH
2
(I) If the comounds has both or at least one Typce C group, then the parent compound is given after thehigher priority group, the other one appears as branches(prefixes) see these examples.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
COOH
HO
salicylic acid(2-hydroxybenzoicacid/ o-hydroxybenzoicacid)
CN
OHC
12
3
4
3
21
4-formylbenzonitrile(p-formylbenzonitrile)(not 4-cyanobenzaldehyde)
NH2
HO1
2
3-aminophenol(m-aminophenol)(not 3-hydroxyanilin
NCH3H3C
NO2
COCH3
SO3H
COCH3
OH
N,N-dimethyl-4-nitroaniline 3-acetylbenzenesulfonic acid 2-hydroxyacetophenone(II) If both groups belong to type A (not type C), then the alphabetic senior group will get the lower locant.
CH3
1-ethenyl-3-methylbenzene(PIN(3-ethenyltoluene)
CH3
NO2
1
4
1-methyl-4-nitrobenzenOr, 4-nitrotoluene
CH3
Cl1
2
1-chloro-2-methylbenzene(PIN(2-chlorotoluene)
OCH3
CH2CH3
1
4
1-ethyl-4-methoxybenzene(PIN(4-ethylanisole)
1
2
HO
H2N 2-(4-aminophenyl)phenol
* If aromatic and aliphatic parts contain type C group, then the part bearing higher priority functionalgroup gives the parent name. If idential functional group present in both the parts, then it will be named asaromatic.
OH
CHO
(4-hydroxyphenyl)acetaldehyde
OH
CH3
CH3
CH3
4-(2,2-dimethylbutyl)phenol
HOOC
COOH
4-(carboxymethyl)benzoic acid
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
1
2
3
NH2
OH
(3-aminophenyl)methanol
O H
phenylm ethanol
Identical groups:
OH
OH
OH
OH
OH
OH
COOH
COOH
pyrocatechol(1,2-dihydroxybenzene/o-dihydroxybenzene)
resorcinol(1,3-dihy droxybenzene/o-dihydroxybenzene)
hydroquinone(quinol/1,4-dihy droxybenzene/p-dihydroxybenzene
phthalic acid(benzene-1,2-dicarboxy licacid)
COOH
COOH
COOH
COOH
CH3
CH3
CH3
CH3
isophthalic acid(benzene-1,3-dicarboxylic acid)
terephthalic acid(benzene-1,4-dicarboxylic acid)
o-xylene(1,2-dimethylbenzene/o-dimethylbenzene)
m-xylene(1,3-dimethylbenzene/m-dimethylbenzene)
CH3
CH3
NH2
NH2
NH2
NH2
NH2
NH2
p-xylene(1,4-dimethylbenzene/p-dimethylbenzene)
benzene-1,2-diamine(1,2-diaminobenzene/o-pheny lenediamine)
benzene-1,3-diamine(1,3-diaminobenzene/m-pheny lenediamine)
benzene-1,4-diamine(1,4-diaminobenzene/p-pheny lenediamine)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
SAQ III.10: Write any one IUPAC name of the following aromatic compounds.
OC H2CO OH
Cl
Cl
COCl
CONH2
NO2O2N
CH3
NH2
Cl
O2N
COOH
SO3H
CH2CH3
Cl
NO2
NO2
Cl Cl CH(CH3)2
NO2
CN
COCH3
Br
I
CHO
CHO
CONH2
H2NOC
COOC2H5
CN
C2H5
CH3
Answer:3-methylaniline(m-toluidine), 1-chloro-2-nitrobenzene(o-nitrochlorobenzene), 3-sulfobenzoic acid, 1-chloro-4-ethylbenzene, 1,2-dinitrobenzene, 1,3-dichlorobenzene, 1-isopropyl -2-nitrobenzene, 4-acetylbenzonitrile, 3-(aminocarbonyl)benzoyl chloride, 1,3-dinitrobenzene, 1-bromo-3-iodobenzene, benzene-1,3-dicarbaldehyde,benzene-1,2-dicarboxamide, ethyl 4-cyanobenzoate, 1-ethyl-4-methylbenzene, 2,4-dichlorophenoxyacetic acid
SAQ III.11: Write the preferred IUPAC names of the following compounds.
(i) CH3
CHO
N
CH3 CH3
(ii)
NH2
CH3
CH3
(iii)
CN
C H 3
CHO
(iv)
CHO
COOH
CH3
(v)NO 2
CH3
COOH
Answer:
(i) 3-[2-(dimethylamino)phenyl]butanal (ii)2-(2-methylprop-1-enyl)aniline(iii) 3-(1-oxopropan-2-yl)benzonitrile (iv)2-(2-formylphenyl)propanoic acid(v) 3-methyl-4-(2-nitrophenyl)but-2-enoic acid
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Tri or polysubstituted benzene:1. If one of the groups belongs to type C, then the name is given after that groups getting locant 1. If morethan one of such groups are there, then the highest priority groups determines the name of the compound.
2. If all the groups belong to type A, then LSL rule determines the name. See these examples.
OH
COOH
CH3
Br
BrBr
NO2
NO2O2N
NH2
BrBr
Br CHO
COCH3
NCCONH2
OHHO
5-hydroxy-2-methylbenzoic acid
1,2,3-tribromobenzene 1,3,5-trinitrobenzene
4-acetyl-2-formylbenzonitrile 2,6-dihydroxybenzamide
65
4
32
1
6
5
4
32
1
3
21
2,4,6-tribromoaniline
65
4
3
2
1
6
5
4
32
16
4
3
21
5
O2N
CH3 Cl
4-chloro-2-methyl-1-nitrobenzene(correct)5-chloro-2-nitrotoluene(wrong)
O2N
H2N Cl
5-chloro-2-nitroaniline(correct)2-amino-4-chloro-1-nitrobenzene(wrong)
3
2
4
1
5
4
32 1
CH2CH3
OC H3
Cl
2-chloro-4-ethy l-1-methoxy benzene
1
2
34
(not 3-chloro-1-ethy l-4-methoxy benzen
1
23
4
CH3
NO2O2N
NO2
2-methyl-1,3,5-trinitrobenzene(PIN(2,4,6-trinitrotoluene)
5
6
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
SAQ:
COOCH3
CH3
NO 2 CHOO2N
COCH3
O2N
CH3 C2H5 COOCH3
COOCH3
Br I
Cl
OC2H5
Cl
CH3
H3C
H3C
NO 2
NH2O2N NO 2
NO 2
COCl
Cl
COOH
Answer:methyl 2-methyl-5-nitrobenzoate, 3-acetyl-5-nitrobenzaldehyde, 4-ethyl-2-methyl-1-nitrobenzene, dimethylphthalate, 1-bromo-3-chloro-5-iodobenzene, 2-chloro-4-ethoxy-1-methylbenzene, 3,4-dimethyl-2-nitroaniline, 1,2,4-trinitrobenzene, 2-chloro-5-chlorocarbonylbenzoic acid
DIAZINES/AZO and AZOXY Compounds:
HN=NH : diazene CH3 N N CH3 (dimethyldiazene)
N N1
N N12
2
diphenyldiazene (1-naphthyl)(2-naphthyl)diazene
(azobenzene) (1,2’-azonaphthalene)
12
N N41
2
N N Cl
Cl 3
1
2 3
(2-naphthyl)phenyldiazene (3-chlorophenyl)(4-chlorophenyl)diazene
(naphthalene-2-azobenzene) (3,4'-dichloroazobenzene)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
1
4
1
22
3N N
NH2 CH3
Cl1N N SO3H4
1-[(4-chloro-2-methylphenyl)diazenyl]naphthalen-2-amine 4-(phenyldiazenyl)benzenesulfonic acid
N N
O1
3
SO3H
N3
diphenyldiazene oxide 3-azidonaphthalene-2-sulfonic acid
(azoxybenzene) (N3– = azido group)
Diazoninum compounds: Compound containing R-N2+ X– are called alkanediazonium halide (not alkyldiazoniumhalide)
H3CCH2
N N Cl H3CCH2
N N Cl (covalent structure)
ethyanediazonium chloride
N N Cl-
N N Cl (covalent structure)
benzenediazonium chloride
1
4
N2+BF4
-HO 7
N N OH
7-hydroxynaphthalene-2-diazonium tetrafluoroborate phenydiazenol (benzenediazonium hydroxide)
CH2NH
2: (diazomethane)
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
POLYNUCLEAR AROMATIC COMPOUNDS
Compounds containing more than one benzene ring fused at the ortho or 1,2 positons are called polynuclearor condensed aromatic compounds. A few examples are given below.
or
1
2
3
45
6
7
8
1
2
3
45
6
7
8
10
(napthalene)
or
1
23
45
6
7
8 9
98
7
6
5 4
32
110
(anthracene)
Then tetracenene(four benzene rings fused linearly), pentacene and so on.Monosubstituted naphthalene:For monosubstituted naphthalene, there are two non-equivalent positions namely 1-(α) or 2-(β).
1
22
22
1
11
Di- or polysubstituted naphthalene:For such compounds the numbering of carbon atoms is shown before. The highest priority functional groupto get the lower locant.
OH
COOH
CHO
H3C
naphthalen-2-ol naphthalene-1-carboxylic acid 6-methylnaphthalene-1-carbaldehyde(β-naphthol)
1
2
CH3
CN
4 5
6
1
OH
COOH
1
NH2
H5C245
6
1-methylnaphthalene-2-carbonnitrile 6-hydroxynaphthalene-1-carboxylic acid 6-ethylnaphthalen-1-amine
Anthracene:For monosubstitued anthracene has 3 non-equivalent position, 1, 2 and 9. But for di- and polysubstitutedanthracene, the numbering has been given before.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
11
11
2
2
2
2
9
9
COOHOH
anthrancene-2-carboxylic acid anthracen-9-ol
12 CHO
CH3
45
OH
CH3
NO2
12
45
7
6
9
5-methylanthracene-2-carbaldehyde 4-methyl-2-nitroanthracen-9-olHeteroaromatics and Heterocyclics:
4 3
52
O1
4 3
52
NH1
4 3
52
S1
2
N1
3
6
5
4
furan pyrrole thiophene pyridine
NH
O
5
4
6
O1
2
3
O1
2
3
4
5
6
3
1 2
4
5NH
3
1 2
4
5O
3
1 2
4
5S
3
1 2
4
5
6N
pyrrole funran thiophene pyridine
N
N
NH CHO O
COOH
pyrazine pyrrole-2-carbaldehyde furan-3-carboxylic acid
N
OH
CH3
3-methylpyridin-4-ol
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Other Heterocyclic Compounds:
NH O O O
O
piperidine tetrahydrofuran(THF) oxane 1,3-dioxane
NH
NH
NH
NH
NH
NH HN
NH
NH
O
piperazine 1,4-dihydropyrazine 1,3-diazinane 1,3,5-triazinane 4-H-pyran(1,4-diazinane)
Bicyclic Compounds:A bicyclic compound is one which can be converted to an open chain acyclic compound by making
cleavage(scission or breakage) of covalent bonds two times.
1st cleavage 2nd cleavage
open chain
bridgehead carbon
bridgehead carbon
bridges
There are two bridge head carbon atoms and three bridges. The bridge may contain only a single covalentbond(no carbon atom).
bicylo[x.y.z]alkanex, y and z are ring size i.e number of carbon atoms in three bridges from highest to lowest bridges. Thisexcludes the two bridgehead carbon atoms. If a bridge has no carbon atom(only a covalent bond) then it willget the numeral ‘0’.alkane will be from (x+y+z) +2 i.e all the carbon atoms. The numbering will start from one bridgeheadthrough the longest bridge to the other bridgehead, then to bridge of intermediate length and shortest bridge.For naming a branched bicyclic compound, the priority order of functional group and LSL to be taken intoaccount.
1
2
3
4
5
67
8
9
10
bicyclo[4.3.1]decane
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
bicyclo[2.2.0]hexane bicyclo[5.3.1]undecane
532 12
0
bicyclo[1.1.0]butane
1 10
5 4
6 1
3
2
CH3
5-methylbicyclo[2.2.0]hex-2-ene
2 1
3
4
5 6
7
11
10
8
9
CH3
3-methylbicyclo[5.3.1]undec-8-ene
CH 3
23
4
5
6
78
9
1
10
6-methylb icyclo[5 .2.1]dec-3-ene
OC H3
O 2N
HO
2
1
4 5
6
7
8
3
9
4- methoxy-2-nitrobicyclo[3.2.2]nonan-6-ol
SAQ:SAQ III.14:Write the names of the following bicyclics.
(i) (ii) (iii) CH3 (iv)
CH3
(v) (vi)
CH3
(vii)
NH 2
(viii) NH2
COOH (ix)
NH2
(x)
OHC
Answer:(i) bicyclo[1.1.1]pentane (ii)bicyclo[2.2.2]oct-2-ene (iii)7-methylbicyclo[4.2.1]non-3-ene (iv)9-ethylbicyclo[3.3.2]decane (v)bicyclo[4.4.2]dodec-11-ene (vi) 8-methylbicyclo[5.2.0]non-2-ene(vii)bicyclo[5.3.1]undec-4-en-2-amine (viii)5-aminobicyclo[4.2.1]non-2-ene-7-carboxylic acid (ix)bicyclo[3.2.2]non-2-en-6-amine (x)bicyclo[3.1.1]hept-2-ene-6-carbaldehyde
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
SPIRO COMPOUNDS:
The compounds in which two rings share one common carbon atom are called spirocompounds.
spiro[x.y]alkane
x and y are chain lengths in the two rings or the number of carbon atoms in the two rings which link to thecommon atom(called spiro atom), which are separted by full stop. Note that the spiro atom is excluded inthese numbers. The numbers are written in increasing order eg. [4.5] unlike that followed in bicycliccompounds(decreasing order). While naming the parent alkane the total number of carbon atoms in thecompound is counted.
4
3
2
1
5
6 7
8
10 9
spiro[4.5]decane
The numbering starts in the smaller size ring from the carbon atom adjacent to the spiro atom andproceeds around the smaller ring back to spiro atom and then proceeds around the second ring(largersize ring). While going from the smaller ring towards the larger ring the lowest set of locants rule iskept in mind. If there is a C=C, then ene should get the lower locant compared to alkyl or other typeA groups.
2
1
3
4 5
8 7
6
CH3
8-methylspiro[2.5]oct-4-ene
9
8
7
65
4
1 0
3
1
2
CH 3
1 -e thy lsp iro [3 .6 ]dec-6-ene
8
7
9
6
5
4
1
3
2
spiro[4.4]nona-2,7-diene
SAQ III.15: Name the following spiro compounds.
(i)
CH3
CH3
(ii)- CH3
CH3
(iii)
C H 3
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(iv) Cl (v)
CH 3
Answer:(i) 1,4-dimethylspiro[2.7]deca-5,8-diene (ii) 6-isopropylspiro[3.5]non-1-ene(iii) 4-methylspiro[2.2]pent-1-ene (iv)1-chloro-5-ethylspiro[3.3]heptane(v) 4-methylspiro[4.8]trideca-1,7,9-triene
SUBSTITUTED OXIRANES(EPOXYALKANES), IMINES, LACTONES, LACTAMS, IMIDES,KETENES
1. Substituted oxirane: The O atom of oxirane is always numbered 1. Alphabetical seniority of alkyl groupsdecides the correct direction of numbering. These are also named as epoxyalkanes, the locants of the epoxyare to be prefixed to it.
H 3C CH CH CH 2 CH 3
O
(2 ,3 -ep ox yp en tan e)
1
23
2 -e th yl-3 -m eth ylox iran e
2. Imines: =NH is called imine group. It is a bivalent group. The name of imine is alkan-x-imine where x is thelocant of imine.
H 3C CH 2 CH 2 CH NH
bu tan -1 -im ine
H 3C CH 3
NHprop an-2 -im in e
3. Lactones: Cyclic esters are called lactones. Butyrolactone, valerolactone, caprolactone are a few examplesof lactones.
H 2C
H 2C
H 2C C
O
OH 2C
CH 2
H 2C C
O
CH 2
O
H 2C
CH 2
H 2CC
O
CH 2
CH 2
O
-bu tyrolactone -valerolactone -caprolacton e
4. Lactams: Cyclic amides are called lactams. Butyrolactam, valerolactam, caprolactam are few examples oflactams.
H 2C
H 2C
H 2C C
O
NHH 2C
CH 2
H 2C C
O
CH 2
NH
H 2C
CH 2
H 2CC
O
CH 2
CH 2
NH
-butyrolactam -valero lactam -caprolactam
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
5. Ketenes: R-CH=C=O are called ketenes. Such compounds are named according to IUPAC rule.Example: CH
3-CH=C=O prop-1-en-1-one
6. Imides: Imides contain -CO-NH-CO- group. It is analogous to acid anhydride except -O-in anhydrideis replaced by -NH- in imide. They are named according to IUPAC rules.
CH3-CO-NH-CO-CH
3N-acetylacetamide.
ALTERNATIVE NAMING PROCEDURE FOR ETHERS AND 20 AMINES
Ethers:(OXA System)
1. Oxygen atom in ether is treated like a carbon atom in finding out the longest continuous chainincluding the oxygen atom. In otherwords, the oxygen atom is counted like a carbon atom in determiningthe the name of parent alkane. The ether group(oxygen atom) is indicated by the prefix oxa withits locant placed before it. Lowest set of locants rule is followed while choosing the direction ofnumbering. Note that ether group (O atom) does not enjoy any priority as functional group.
CH36
5
O4
3
2
CH31
CH3
(2-methyl-4-oxahexane)
Note that IUPAC does not have a fixed procedure for naming ethers, although the one discussedbefore(alkoxyalkane) is the preferred name. The oxaalkane procedure of naming ether is simpler,although used to a lesser degree of preference.
Cyclic ethers:When oxygen atom remains as a part of a ring, it is a cyclic ether. The systematic names of these ethers
and their alternative names according to oxa system are given below.
O
oxirane
O
oxetane
O
oxacyclopentane(tetrahydrofuran or THF)
O
O
1,4-dioxacyclohexane(1,4-dioxane)(oxacyclopropane) (oxacyclobutane)
Note that oxirane is also commonly called ethylene oxide or epoxyethane.
Sec-amines (AZA System)
Like oxygen atom in ether, the nitrogen atom in a sec-amino group( NH) is counted like a carbon atomin finding out the longest continuous chain. The prefix aza is used for the amino function with its locant beforeit.
CH35
4
NH3
2
1
O
OH
3-azapentanoic acid [ 2-(ethylamino)acetic acid/N-ethylglycine]
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
Trivial System(Common Names):
Type of Carbon atoms:
(a) Primary (10) (b) secondary (20) (c) tertiary(30) (d) quaternary(40)
CH3 CH
CH3
CH2 C
CH3
CH3
CH3
10 2030 40
Types of Alkyl Groups:
(a) n-alkyl : straight chain : example n-propyl, n-butyl, n-pentyl etc. ( n = normal)
CH3 CH2 CH2 CH3 CH2 CH2 CH2
n-propyl n-butyl
(b) sec-alkyl: derived from a 20 carbon atom. The carbon bearing the unsatistfied valency has one H atom.
CH3 CH2 CH CH3 CH3 CH2 CH CH2 CH3
sec-butyl sec-pentyl
CH3 CH2 CH2 CH CH3
sec-pentyl
There is only one sec-butyl and hence can be used in naming. But there are two sec-pentyl groups, hence cannotbe used for naming. Can you say how many sec-hexyl group you can have from hexane ? Again two. You willget clear picture about this in the chapter ‘Isomerism’.
(c) tert-alkyl: derived from a 30 carbon atom. The carbon bearing the unsatisfied valency has NO H atom in it.
CH3 C
CH3
CH3
CH3 C
CH3
CH2CH3
tert-butyl tert-pentyl
Since there is one from each of the above, they can be used in naming.
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
(d) isoalkyl group: contain -CH3 branch at the 2nd position.
CH3 CH
CH3
CH3 CH
CH3
CH2 CH3 CH
CH3
CH2 CH2
isopropyl(sec-propyl) isobutyl isopentyl
Note that isopropy is also sec-propyl as it satisfies both the definitions. But isopropyl is preferred.
(d) neopentyl group:
CH3 C
CH3
CH3
CH2 (neopentyl)
Naming by Common System(traditional or trivial system):
CH3 CH2 CH2 CH3 CH3 CH2 CH2 CH2 CH3
n-butane n-pentane
CH3 CH
CH3
CH3 CH3 CH
CH3
CH2 CH3
CH3 C
CH3
CH3
CH3
isobutane isopentane neopentane
CH3 CH2 CH
CH3
ClCH3 C
CH3
CH3
CH2 OH C
O
CH
CH3
CH3
CH3
sec-butyl chloride neopentyl alcohol isopropyl methyl ketone
O C
CH3
CH3
CH3
CH2CH3 tert-butyl ethyl ether
Nomenclature of Organic Compounds
Dr. S.S.Tripathy
BRACKET SYSTEM OF STRUCTURE WRITING:
(CH3)2CHCH(OH)C(CH3)2COOH =CH
CH3
CH3
CH
OH
C
CH3
CH3
COOH
(CH3)3CCOCH(CH3)(CH2)3CH3 = C
CH3
CH3
CH3
C
O
CH
CH3
CH2 CH2 CH2 CH3
Short Notations:
n-Bu (n-butyl); i-Pr (isopropyl); t-Bu (tert-butyl); n-Pr ( n-propyl); Me(methl): Et(ethyl)