nomenclature of organic compounds.pdf

8/20/2019 Nomenclature of Organic Compounds.pdf

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1

Learning Frameworkof the Chapter . . .

1-1 Introducon1-2 Naming Hydrocarbons According to IUPAC

Convenons

1-3 Naming Compounds Containing One or MoreSimilar Type of Principal Funconal Groups

1-4 Naming Compounds Containing More ThanOne Type of Principal Funconal Groups

1-5 Nomenclature of Bicyclic Compounds

1-6 Nomenclature of Spiro Compounds

Nomenclatureof OrganicCompounds

The purpose of the IUPAC system of nomenclaturis to establish an international standard of namincompounds to facilitate communication. The goaof the system is to give each structure a uniquand unambiguous name, and to correlate eacname with a unique and unambiguous structureIn this Chapter, we will develop the knowledge ousing IUPAC conventions for naming an organicompound and to write the appropriate structure oa compound from its given IUPAC name.

1-1 IntroductionBecause of infinitely large number of organic compounds

existing already and several new compounds being either

synthesized or discovered everyday, each specific compound

requires a unique name so that it can be recognized all over the

world by that name. Just as each distinct compound has a unique

molecular structure which can be designated by a structural

formula, so each compound must be given a characteristic and

unique name.


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2 Essenal Organic Chemistry

As organic chemistry grew and developed, many compounds were given trivial names, which are now commonly use

and recognized. Some examples are

Name Methane Butane Acetone Toluene Acetylene Ethyl alcoho

Formula CH4 C4H10 CH3COCH3 CH3C6H5 C2H2 C2H5OH

Such common names often have their origin in the history of the science and the natural sources of specific compounds, bu

the relationship of these names to each other is arbitrary, and no rational or systematic principles underly their assignmentsEarlier, organic compounds were named on the basis of their source or after the name of discoverer. Due to their larg

number, it has becoming difficult for the scientific world to keep record of all organic compounds having typical name

originating from source, discoverer or place of discovery etc.

In order to keep track of such a large number of organic compounds with a wide range in complexity of their skeleton

the “International Union of Pure and Applied Chemistry” (IUPAC) has set-up some standard conventions for systemati

naming of organic compounds so that they can be easily recognized from their names and their structure can be drawn usin

IUPAC conventions.

1-1A The IUPAC Systematic Approach to NomenclatureA rational nomenclature system should do at least two things. First, it should indicate how the carbon atoms of a given

compound are bonded together in a characteristic lattice of chains and rings. Second, it should identify and locate an

functional groups present in the compound. Since, hydrogen is such a common component of organic compounds, itamount and locations can be assumed from the tetravalency of carbon, and need not be specified in most cases. The IUPA

nomenclature system is a set of logical rules devised and used by organic chemists to circumvent problems caused by arbitrar

nomenclature. Knowing these rules and given a structural formula, one should be able to write a unique name for ever

distinct compound. Likewise, given a IUPAC name, one should be able to write a structural formula. In general, an IUPA

name will have three essential features

A root or base indicating a major chain or ring of carbon atoms found in the molecular structure.•

A sufx or other element(s) designating functional groups that may be present in the compound.•

Names of substituent groups, other than hydrogen, that complete the molecular structure.•

As an introduction to the IUPAC nomenclature system, we shall first consider compounds that have no specific functiona

groups. Such compounds are composed only of carbon and hydrogen atoms bonded together by sigma bonds (all carbons ar

sp3 hybridized).

According to IUPAC conventions, organic compounds are classified into two broad categories for the purpose of namingOne being “hydrocarbons” – which contain only carbon and hydrogen and other being “derivatives of hydrocarbon” which

besides containing carbon and hydrogen, also contain some other atoms viz . oxygen, nitrogen, halogen, sulphur etc.

1-2 Naming Hydrocarbons According to IUPAC Conventions

1-2A Saturated Unbranched-Chain HydrocarbonsThe first four saturated unbranched acyclic (non-cyclic) hydrocarbons are called methane, ethane, propane and butane

Names of higher members of this series consist of a numerical term followed by “ane”. Examples of few unbranched

saturated, acyclic hydrocarbons are shown in the Table 1.1.

Table 1.1 (n = Total number of carbon atoms)

n Name n Name n Name n Name

5 Pentane 14 Tetradecane 23 Tricosane 50 Pentacontane

6 Hexane 15 Pentadecane 24 Tetracosane 60 Hexacontane

7 Heptane 16 Hexadecane 25 Pentacosane 70 Heptacontane

8 Octane 17 Heptadecane 26 Hexacosane 80 Octacontane

9 Nonane 18 Octadecane 27 Heptacosane 90 Nonacontane

10 Decane 19 Nonadecane 28 Octacosane 100 Hectane

11 Undecane 20 Icosane 29 Nonacosane

12 Dodecane 21 Henicosane 30 Triacontane

13 Tridecane 22 Docosane 40 Tetracontane


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Nomenclature of Organic Compounds Chapter 1

1-2B Structural Formula and Bond-Line StructureStructural formula of a compound demonstrate the connectivity of atoms in the molecule ie, it represents a specifi

bonding pattern, a characteristic of the given molecule. Some of the structural formula and its descriptions are mentione

below :

CH CH CH CH CH CH33 2 2 2 2

n-hexane

H—C—C—C—C—C—C—H

H H H H H H

H H H H H H

H

H

H

H

CC

C

C

C

C

H

H

H

H

H

H H

H H

H

H CH—CH CH —C—CH CH3 2 2 2 3C—

CH3

CH3CH3

2, 5, 5-trimethyl heptane

H—C—C—C—C—C—C—C—H

H H H H C H

H C H H C H

H

H

HH H

HHHHHH

H

H

CC

H H

H H

H

H

H H

H

HH

HHH

HHH

HHH

C

C

C

C

C

C

C

C

As shown in the above structures, carbon is tetravalent and associated with four covalent bonds (C—H or C—C bonds

1-2Aa Bond-Line Structures (Topological Structures)In frequent writing, organic molecules are usually represented by a line structure in which letters ‘C’ for carbon and ‘H

for hydrogen are not shown. In topological structure, each point of inflexion and the terminal points represent carbon atom

and the visible line between two points represents carbon-carbon bonds. At each carbon, the number of hydrogen equals to

(4–the no. of visible bonds at that carbon) eg ,

H—C—C—C—C—C—C—H =

H H H H H H

H H H H H H

n-hexane

H—C—C—C—C—C—C—C—H=

H H H H C H

H C H H C H

H

H

HH H

HHHHHH

4C—C bondsno Hie,

3C—C bondsoneHie,

2, 5, 5-trimethyl heptane

C

C C

C C

C

H

HH

HH

Cyclohexane

H

HH

H

HHH

=

H—C—C—C C—H=

H H H

H C

HHH

3-methyl-1-butene

H

==


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1-2Ab Univalent RadicalsUnivalent radicals derived from saturated unbranched hydrocarbons by removal of one hydrogen atom from a terminal carbo

atom are named by replacing –“ane” of the parent name by “yl”. The carbon atom with the free valence is numbered as 1.

CH3CH2CH2CH2 —Butyl4 3 2 1

H3C—(CH2)8 —CH2 —Decyl etc.10 1

1-2C Saturated Branched-Chain Acyclic HydrocarbonIn case of a saturated, branched chain hydrocarbon, following rules are applicable in the same sequence

Rule 1 Selection of the longest carbon chain : The longest carbon chain gives parent name to the compound.

Rule 2 Numbering the longest chain : Longest chain is numbered starting from a terminal carbon. Numbering is donin such a way that lowest possible number is given to the side chain as

CH3

H3C CH3(1)

Longest chain has seven carbon atoms. If we start numbering from the left terminal, side chain methyl group comes at 5

carbon while if numbering starts from right terminal, side chain methyl group comes at 3rd carbon which is a lower numbe

Hence, the correct way of numbering will be to start from the right terminal.

When more than one locants (side groups) are present, than that number series is “Correct” which contain the lowe

number on the occasion of first difference as

H3C

CH3

CH3CH3CH3

(2)

The two number series existing in compound (2) are 2,3,5 and 2,4,5. The first one is correct and second is incorrect.

Rule 3 When writing names of branched, saturated hydrocarbon, locants are written rst in alphabetical order (irrespective of their numbers) followed by name of parent chain. Locants in the name must be followed by its number separated b

hyphen (-). If more than one locants of similar types are present at the same or different positions, di, tri etc. are prexed

before the locants. Adjacent numbers must be separated by comma (,).

Applying the above mentioned rules, compounds (1) and (2) described just before can be named as

CH3

CH3H3C7

65

43

21

3-methylheptane

CH3

CH3

CH3CH3

H3C6

54

32

1

2, 3, 5-trimethyl hexane(not 2, 4, 5-trimethyl hexane)

Some other examples applying the above rules are

6-ethyl-2, 4-dimethyl nonane

(not 2,4-dimethyl-6-ethylnonane)

9 5 3 21

8

76 4

H3C

H3C

CH3 CH3

CH34-ethyl-2, 3, 6, 6, 8-pentamethyl-5-propylnonane

(not 6-ethyl-2, 4, 4, 7, 8-pentamethyl-5-propylnonane)

H3C

H3C

H3C

CH3 CH3

CH3

CH3CH3

CH3

9 5 32

1

8

76

4

(In alphabetical order, initials of originalname of the locant is considered ie, ‘m’of methyl is considered here not ‘d’ of di)


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Rule 4 When two different alkyl locants are equidistant from the two ends of main chain, they are numbered ialphabetical order as

CH3

H C3

9

5 32

18

7 6 4

CH3

CH3

10

4-ethyl-7-propyldecane(not 7-ethyl-4-propyldecane)

3-ethyl-7-methylnonane(not 3-methyl-7-ethylnonane)

CH3H C39

5

3

2

1

8

7

6 4

CH3

CH3

Rule 5 Following common names are retained in IUPAC system for unsubstituted hydrocarbons only

CH3H C3

CH3

Isohexane

CH3H C3

CH3

Neopentane

CH3

CH3H C3

CH3

Isopentane

CH3H C3

CH3

Isobutane

Rule 6 Branching in the branch: If there is a complex branch which is branched further, branch is numbered separatelstarting from the carbon directly bonded to parent chain and name of branch is written in small parenthesis ( ) before the nam

of parent hydrocarbon as

Here the branch is dimethylpentyl ascomplete single substituent

CH3

CH3

21

CH3

3

45

687

1011

12

H C313

H C35

43

21

CH37-(1, 2-dimethylpentyl)-5-ethyltridecane [not 5-ethyl-7-(1,2-dimethylpentyl) tridecane]

9

In case where name of complex branch are composed of identical words, priority is given to that branch which has locan

at the lowest number as

CH3

2

3

4

5

68

7911

12

H C3

1310

H C3

4

H C3

3

21

H C3CH

31

2

3

4

6-(1-methylbutyl)-8-(2-methylbutyl) tridecane

CH32

34

58

6H C3

7

H C3 CH3

CH31

4-isopropyl-5-propyloctane

Both branch have the common word ‘‘butyl’’ therefore, branch at position 6

will have priority since, it has locant at C-1 while other has locant at C-2

Rule 7 The presence of identical complex branch, each substituted in the same way, may be indicated by the appropriatmultiplying prex bis, tris, tetrakis, pentakis etc. The complete expression denoting such side chain may be enclosed i

parenthesis as

H C3 CH3

1

CH32

6 5 4 3

2

CH3

CH3

78

910H C3

H C3 CH3

1

2

H C3

1

3

3

5,5-bis(1, 1-dimethylpropyl)-2-methyldecane

CH3

6

87911

12

H C313

10

H C3 CH3

1

5,5-dimethyl-6-(1,1-dimethylbutyl)-6-pentyltridecane

23

4

CH3

H C31

23 4

5CH3H C3


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Rule 8 If chains of equal length are competing for selection as main chain in a saturated, branched acyclic hydrocarbonthe choice goes in series to

(a) The chain, which has the greatest number of side chains

CH3H C37 4

CH3

6 5 3 2

1

CH3H C3

CH3

CH3H C34

CH3

3 2

1

CH3H C3

CH3

6

5

7

CH3H C31 4

CH3

2 3

CH3H C3

CH3

7 6

5

Correctly numbered (four locants)

2, 3, 5-trimethyl-4 propylheptane

(Three locants) (Two locants)

(Wrongly numbered)

(b) The chain whose side chain has lowest numbered locants

CH3

H C3 1

4

CH3

CH3

23

CH3H C3

7 65

Wrongly numbered : locantsare at 2,4,6 positions

CH3

H C3

4

CH3

3 2

1

CH3H C3

CH3

56

7

Correctly numbered (locants are at

2,4,5 positions) 4-isopropyl-2,5-

dimethylheptane

(c) The chain having the greatest number of carbon atoms in the smaller side chain

CH3

213

45

68 7

1011

12

H C3

13

H C3

CH3

9

CH3

CH3 CH3

CH3CH3

H C3

H C3

H C3

7,7-Bis(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyltridecane

(d) The chain having the least branched side chain

CH3

23

45

68 79

11

H C310

1

CH3

CH3H C3

CH3

12

CH368

7911H C310

6-(1-isopropylpentyl)-5-propyldodecane Wrongly numbered

CH3

CH3H C3

CH3

12

1 2 34

5


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Problem 1-1 Write IUPAC names of the following hydrocarbons

I II III

VIV

76

5 34 2

1

I3-ethyl-5-methylheptane

When same number series (here 3,5) are

obtained from both terminals, preference

goes to alphabetical order.

12

35

4 6

7

II5-ethyl-3,3-dimethyl heptane

Lower number coming at first occasion of

difference determine the numbering

pattern-here 3,3,5 not 3,5,5.

1

2

34

56

7

8

III6-ethyl-3,4-dimethyl octane

1

2

34

579

8 610

IV5-butyl-5-methyl-4-propyl decane

Longest chain with maximum number of locants

becomes the parent chain.

3,5-diethyl-2,3,5,6-tetramethyl heptaneV

12

3

4

5

6 7

Longest chain with maximum number of locants becomes the parent chain.

Problem 1-2 Write. structural formula of the following hydrocarbons ( I ) 4-ethyl-2,2,6,6-tetramethyl heptane.

( II ) 4-ethyl-2,3-dimethyl hexane.

( III ) 6-ethyl-3-methyl-5-propyl nonane.

( IV ) 5-(1,2-dimethylpropyl)-5-(2,2-dimethylpropyl) nonane.

(V ) 5-(1,2-dimethylpropyl)-6-(1-ethylpropyl) decane.

I II III

IV V


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I II

III IV

I

2

8

7

1

4 2

1

12

5

3

3

69

3

II

8

1

42 5

36

9

107

5-(1-ethyl-2, 2-dimethylpropyl)-5 5-(1, 1-dimethylpropyl)-6-

-(1, 2, 2-trimethylpropyl) nonane (2, 2-dimethylpropyl) decane

III

13

2

6

10

47

9

85

IV1

2

34

56

78

910

11

8-ethyl-2, 3, 8-trimethyl-4, 7-dipropyl decane 6, 7, 8-triethyl-3-methyl undecane

Problem 1-4 Draw structures of all alkanes and write their IUPAC name having molecular formula C7H16.

Heptane 2-methylhexane

2,4- dimethylpentane 3-ethylpentane 2,2,3,-trimethyl butane

3-methylhexane 2,2-dimethylpentane

2,3-dimethylpentane

1-2D Unsaturated Hydrocarbons

Rule 1 Unsaturated, unbranched acyclic hydrocarbons having one double bond are named by replacing “–ane” of thname of corresponding saturated hydrocarbon with the ending “-ene”. If there are two or more double bonds, the ending wi

be “-adiene”, “-atrine” etc. The chain is so numbered as to give lowest possible number to the double bond.

1

2

3 5

4 6

7CH3H3C

1

2

3 5

4 6

7CH3H3C

7

6 2

15 3 CH2H3C

3-heptene 2,4-heptadiene 1,3,5-octatriene

4

8


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Following unsystematic names are retained in IUPAC

CH2==CH2 (Ethene) CH2==C==CH2 (Allene)

Rule 2 Unsaturated, unbranched, acyclic hydrocarbons having one triple bond are named by replacing the ending “-aneof corresponding saturated hydrocarbon with the ending “-yne”. If there are two or more triple bonds, the ending will b

“-adiyne”, “-atriyne” etc. The chain is so numbered as to give lowest possible number to the triple bond.

2

3

4

5CH3HC

1

2

3 5

46CH3

H3C

7

6 2

5 3 CH3H3C 4

8

1

1

Pentyne 2-hexyne 2,4,6-octatriyne

(Its triple bond is at terminal positions,

therefore, it need not numbered)

Rule 3 Unsaturated unbranched acyclic hydrocarbons, having both double and triple bonds are named by replacinending “-ane” from the name of the corresponding saturated hydrocarbons by “-enyne”, “-adienyne”, “-atrienyne” “-enediyne

etc. Numbers as low as possible are given to double and triple bonds even though this at times gives “-yne” a lower numbe

than “-ene”.

1

2

3 5

4 6

CHH2C

2

3

4

5CH3HC

1,3-hexadien-5-yne 3-penten-1-yne

1

Preference has been given to numbering 1,3 rather than to 2,4 and not to triple bond over double bond.

Rule 4 When there is a choice in numbering between double and triple bond (this occur when double and triple bondare equidistant from the two terminal), the double bonds are given lowest numbers(ene comes before yne in alphabetica

order).

45

2

CH2HC 3

17

6 2

15 3 CH3

CH3

H3C48

1-penten-4-yne 4-methyl-6-octen-2-yne

Here both double bond and triple bonds are

equidistant from terminals hence, numbering is

done in alphabetical order.

Here both double bond and triple bonds are

equidistant from terminals hence, preference

goes to lower number to other locant.

Rule 5 Unsaturated branched acyclic hydrocarbons are named as derivatives of unbranched hydrocarbons which contaimaximum number of double and triple bonds.

HC

CH3

CH2

CH3

65

4

3

21 not 5

4

8

12

3

6

7

or 5

4

8

12

36

7HC

CH3

CH2

CH3

HC

CH3

CH2

CH3

3,4-dipropyl-1,3-hexadien-5-yneCarbon chain with maximum number of double/triple bonds is

selected as parent chain though it contains less no. of

carbon than other longer chain but with lower no. of

double/triple bonds, existing in the molecule.

Rule 6 If there are two or more chain competing for selection as the chain with maximum number of unsaturated bondthen the choice goes to


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(i) That one with greatest number of carbon atoms

The above numbering system also hasa main chain with three double bonds but one

carbon less than other chain (mentionedon left)

5-vinyl-1,3,5-octatriene

54H C3

CH2

CH2

1

2

3

6

78

34

2

H C3CH2

CH2

7

6

5

1

(ii) If the number of carbon atoms being equal, the one containing maximum number of double bonds is selected as th

parent chain.

5-ethynyl-1,3,6-heptatriene

not5

4

H C2 CH2

CH

1

2

3

6

7

54

H C2 CH2

CH

1

2

3

6

7

4-vinyl-1-hexen-5-yne4-ethynyl-1,5-hexadiene

notCH21

3

5

6

4 2

CH2

CH21

6

35

4 2

CH2

Following name is retained for unsubstituted compound only

but

CH2

CH3Isoprene

H C2

2,3-dimethyl-1,3-butadienenot 3-methylisoprene

CH2

CH3

H C2

CH3


I II III

IV V

1

2

34

5 6

II2,5-dimethyl-3-heptene

(or 2,5-dimethylhept-3-ene)

III3-propyl-1,4-pentadiene

2

4-ethyl-5-methyl-2-hexene(or 4-ethyl-5-methylhex-2-ene)

I

1

4

45

67 5

23

13


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Nomenclature of Organic Compounds Chapter 1 1

3-ethyl-2-methyl-4-propyl-1,5-hexadieneIV

3-ethyl-6-methyl-2,6-octadieneV

1

3

2

4

56

8

76

5

43

2

1


I II III

IV V

I4.4-dimethyl-1-pentyne

II5-ethyl-5,6-dimethyl-2-heptyne

III3-(1,2-dimethylpropyl)-1,5-hexadiy

5

4

3

2

1

24

5

7 6

3 1

3

21

4

5

6

2

1

34

5

12

5

4

3

IV

3-(1-ethylpropyl)-1,4-pentadiyne

V3-butyl-3-propyl-1,4-pentadiyne


I II III

IV V

6

5 1

4 2

37

I5-hepten-1-yne

(or Hept-5-en-1-yne)

• Preference has gone to lower locant

number, not to triple bond.

• When ‘ene’ follow ‘yne’, ‘e’ of ene is

elided and written as enyne.

2

3

4 6

51

II1-hexen-5-yne

(or Hex-1-en-5-yne)

• Here both double bond and triple bonds are

equidistant from terminals, hence alphabetical

order is followed in numbering the parent chain.


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2

3 7

4 6

51

III1,3-heptadien-6-yne

8

7 3

6 4

59 1

2

IV3,8-nonadien-1-yne

V8-nonene-1,3-diyne

(Here 'ene' is used because nowit follows consonent 'd')

8

7 3

6 4

59 1

2

Problem 1-8 Write structural formulas of the following hydrocarbons ( I ) 3-ethyl-5-methyl-1 ,6-heptadiene. ( II ) 3 ,4-diethyl-1 ,4-hexadiene.

( III ) 5-hepten-1-yne ( IV ) 4-ethenyl-3-ethyl-1 ,6-octadiene.

(V ) 3 ,3-diethynyl-1 ,4-pentadiyne.

I II III

IV V

Problem 1-9 Draw structures and write IUPAC name of all the alkenes with their molecular formula C5H10.

1-pentene 2-pentene 2-methyl-1-butene 3-methyl-1-butene 2-methyl-2-butene

Problem 1-10 Draw structures and write IUPAC name of all the alkynes with their molecular formula C5H8.

1-pentyne 2-pentyne 3-methyl-1-butyne

1-2E Naming Monocyclic Hydrocarbons

Rule 1 Name of monocyclic, saturated hydrocarbons are formed by attaching the prex “cyclo” to the names of acyclisaturated hydrocarbon with same number of carbons

Cyclopropane Cyclopentane Cyclohexane Cyclo-octane

Rule 2 Name of unsaturated monocyclic hydrocarbons (with no side groups) is formed by substituting “-ene”, “-yne“-adiene”, “-atriene”, “-adiyne” etc for “ane” in the name of corresponding cycloalkane eg,

1,3-cyclohexadieneCyclohexene 1,4-cyclohexadiene 1-cyclodecen-4-yne 3-methylcyclohexene

1

2

3

4

5

CH3

1

23


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H C3 H C3CH3

CH3

4

41 2

2

3

1,2,4-trimethylcyclohexene 4-ethyl-5-methylcyclohexene

H C3

H C34

1

3

5-ethyl-4-methylcyclohexene

H C3

2

CH3

CH3

H C34

1

24

21

H C3 35

1,3,5-trimethylcyclohexenenot 2,4,6-trimethylcyclohexene

1not

3

5-methyl-1,3-cyclohexadiene

If alkyl groups are equidistant from double bond alphabetical order is

followed in numbering

Rule 3 If a straight chain substituent attached to monocyclic hydrocarbon has greater number of carbon in the maichain than the cyclic ring becomes substituent as

CH3

1

1-cyclopropyl-3-ethyl-2,4-dimethylhexane

23

4

5

1-cyclopentyl-3-ethyl-1,4-pentadiene

CH2

CH3

CH31

H C3

2 3 4

5

6CH3

Problem 1-11 Write IUPAC names of the following substituted cyclic hydrocarbons

I II III IV V

1

5

3

3

5 1

I

1-ethyl-3-isopropyl-5-methyl cyclohexane

II

1-cyclopropyl-3-methyl-5-propyl cyclohexane

Here numbering is done in alphabetical order because

all locants are equidistant from one another

1

3

1

6

III

3-methylcycloheptene

IV

1-ethyl-6-isopropyl-3-methyl cyclodecane

V

Cyclopropylcyclopropane

3


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Problem 1-12 Write IUPAC names of the following substituted cyclic hydrocarbons

I II III

IV V

I

5-ethyl-1,2-dimethyl-1,3-cyclohexadiene

II

3,7-diethyl-1,4-cycloctadiene

4

1

5

23

4

5

67

32

1

III

1,4-dicyclohexylcyclohexene

IV

1,2,3-tricyclopropylcyclopropane

V4-cyclohexylcyclopentene

1

2

4 1

23

42

1


I II III IV

II

Cyclohexylethyne

I

2,3-dicyclopropyl-1,3-butadiene

1

2 3

4

III

4-(3-cyclopropylcyclopentyl)cyclohexene

1

2 3

4 1'

2'3'

IV

4-(2-cyclobutenyl)cyclohexene

1

2

3

4 1' 2'


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Problem 1-14 Draw structures of the following hydrocarbons( I ) 3,3-dimethylcyclohexene ( II ) 4-ethyl -6-methylcycloheptene

( III ) 4,5-diethyl -7-methyl cycloctene ( IV ) 1,4-dicyclopentylcyclopentene

I II III IV

1-2F Substituted Aromatic HydrocarbonsFollowing names for the substituted monocyclic aromatic hydrocarbons are retained

Benzene Cumene Toluene Styrene

CH2H C3 CH3CH3

CH3

o-xylene

CH3

m-xyleneCH3

CH3 CH3

H C3 CH3Cymene

p-xylene

CH3

CH3Mesitylene

CH3

CH3

H3C

Rule 1 Other monocyclic substituted hydrocarbons are named as derivatives of benzene or one of the compounds listeabove. However, if the substituent introduced into such a compound is identical with already present in that compound, the

the substituted compound is named as derivatives of benzene as

CH2

H C2

1,4-divinylbenzene

CH2

1-methyl-3-vinylbenzene 1,2,3-trimethylbenzene

CH3

CH3

CH3

Rule 2 The positions of substituents is indicated by numbers except o-(ortho), m-(meta), p-(para) may be used in placof 1,2- , 1,3- , and 1,4-, respectively, when only two substituents are present. The lowest possible number given to the substitu

ent coming 1st in alphabetical order except that when names are based on those of the compounds mentioned in the beginnin

of section-E.

H C3 H C3CH3

CH31-ethyl-4-pentylbenzene 1,4-dipropylbenzene 3,5-diethyltoluene

CH3

CH3H3C

H C2

4-ethylstyrene p-ethylstyrene

CH3

1,2-dimethyl-3-propylbenzene 1-butyl-3-ethyl-2-propylbenzene

CH3CH3

CH3CH3

CH3

CH3


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I II III IV

1

2

4

I1,2,.4-trimethyl benzene

2

1

4

II1,4-diisopropyl-2-propyl benzene

1

2 3

5

III1,3-diethyl-2,5-dimethyl benzene

1 3

IV1-cyclohexyl-3-cyclopentyl benzene

1-2G Naming Halogen Substituted CompoundsSubstitutive naming of halogen compounds are formed by adding the prefixes “fluoro-“, “chloro-”, “bromo”- or “iodo”- to th

name of parent compound.

CH3

Cl

H3C1234

6 5789

ClCl

CH3

Cl

H3C 3

2

561

4 CH3

Cl

H3C 12346 57

8

Br

3-chlorohexane 3,4,7-trichlorononane 5-bromo-2-chloroctane

If there is a choice between the two halides for numbering, alphabetical order is followed eg ,

CH3

Br

2 31

4

H3C

Cl

6 1 2

35

4 F

Br I

4 5 6

13

2 ClF

2-bromo-3-chlorobutane 1-bromo-3fluorocyclohexane 1-chloro-3-fluoro-5-iodocyclohexane

1-3 Naming Compounds Containing One or MoreSimilar Type of Principal Functional Groups

Name of such compound which contain principal functional group ends with suffix of that group provided by IUPAC

Suffixes and prefixes for some of the common functional group is given in Table-1.2.


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Table 1.2 Sufxes and Prexes for common functional groups

Class Formula Prex Sufx

(1) Acid halide — CO — X Halocarbonyl Carbonyl halide

(2) Alcohols — OH Hydroxy -ol

(3) Aldehydes — CHO

— (C)HO

Formyl

Oxo-

Carbaldehyde

-al

(4) Amides — CONH2 — (C)ONH2

Carbamoyl Carboxamide

-amide

(5) Amines — NH2 Amine -amine

(6) Carboxylic acid — COOH — (C)OOH

Carboxy -carboxylic acid

-oic acid

(7) Ethers — O R Alkoxy

(8) Esters — COO R — (C)OO R

R-oxycarbonyl R-carboxylate

R-oate

(9) Ketones (C)==O Oxo -one

(10) Nitrile — CN — (C)N

Cyano -carbonitrile

nitrile(11) Sulphonic acid — SO3H Sulpho -Sulphonic acid

(Formulae containing carbon in parenthesis indicates that the carbon is part of main chain)

1-3A AldehydesAcyclic mono- and dialdehydes are named by adding suffix “-al” or “-dial” to the name of acyclic hydrocarbon with th

same number of carbon atoms, eliding the final “e” of the hydrocarbon name before “a”. Numbering starts from the carbo

of the aldehyde group — CHO.

CHO1

Pentanal

CH CHO3

Ethanal

CHOH3C

H3C7

6

5

43

1

2

CHOOHC

43

1

2

H3C

56

4-ethyl-2,5-heptadienal 2-ethylhexandial

If the parent chain contain more than two — CHO groups, they are named as carbaldehyde and carbon of — CHO is no

counted in main chain as

CHOOHC

32

1

4

Butane-1,2,4-tricarbaldehyde

CHO

CHO

Cyclohexanecarbaldehyde

4

3

2

CHO1

4-cyclopentylbutanal

CHOOHC

43

2

5

3-(formylmethyl) hexanedialor 3-(2-oxoethyl) hexanedial

CHO

16

1-3B KetonesKetones are named substitutively by adding a suffix such as “-one”, “-dione” etc to the name of parent hydrocarbon

CH33 2

14

O

5H3C

CH3

O

C6H5

O

2-pentanone 1-phenylpentane-2,3-dione 4,6-dimethylhept-3-ene-2,5-dione

O

H3C

O

CH3CH3

CH31

23

4567

nomenclature of organic compounds.pdf

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