Nomenclature of Aliphatic/Acyclic compoundstheuranium.org/content-images/10-organic-nomenclature.pdfNomenclature of Organic Compounds Dr. S.S.Tripathy Nomenclature of Aliphatic/Acyclic

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)


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


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


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.)


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)


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)


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


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


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.


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


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)


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).....


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)


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


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


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


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].


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


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


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


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


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


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


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.


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.


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


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


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.


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.


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


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)


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


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


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)


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)


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.


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


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


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


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


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


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]


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.


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


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)

Documents

Nomenclature of Aliphatic/Acyclic compoundstheuranium.org/content-images/10-organic-nomenclature.pdfNomenclature of Organic Compounds Dr. S.S.Tripathy Nomenclature of Aliphatic/Acyclic