IUPAC NOMENCLATURE (Organic Chemistry)
CLASSIFICATION OF ORGANIC COMPOUNDS (iv) Heterocyclic: The ring system is made up of two or
The ability of carbon to combine with large number of more than two types of atoms. They may be
elements especially O, N, S, X etc, to undergo catenation to (a) Alicyclic: e.g.
form chains of varying lengths and shapes and existence of
isomers has led to the formation of more than five million
organic compounds. These have been classified into the
following main groups
(b) Aromatic: e.g.
(i) Acyclic or open chain compounds:
For example:
CLASSIFICATION BASED ON FUNCTIONAL GROUPS
On the basis of functional groups which confer characteristi c
properties on them, the organic compounds have been
classified as follows
Class Functional group
Halides X (Cl, Br, I) Halo
(ii) Cyclic or closed chain compounds.: For example
Esters
Olefins Alkenes >C=C<
Acid halides
(iii) Homocyclic: The ring system is made up of one type of Acetylenes / Alkynes — C ≡ C—
atoms generally carbon Anhydrides
(a) Alicyclic: The cyclic compounds resembling open chain
aliphatic compounds. Alcohols — OH (Hydroxy )
For example: Cycloalkanes Amines −NH2
(b) Aromatic: The benzene, napthalene and their
derivatives etc are homocyclic aromatic compounds Aldehydes
Ketones
Sulphonic acid −SO3 H
Acids
Amides
HOMOLOGOUS SERIES A group of a particular class of
compounds where a preceeding or succeeding member
differ by one – CH2 . The members of the series are known as
homologues. The homologues
1
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, IUPAC NOMENCLATURE (Organic Chemistry)
(i) have the same general formula Cn H2n+2 or Cn H2n +1 X Primary Word Prim. Sec. IUPAC
(ii) molecular weight differing by 14 of two successive prefix root suffix suffix name
members Cyclo hex ane - Cyclohexane
(iii) can be prepared by general methods of preparation immediately before the word root. eg.
(iv) have almost similar chemical properties
(v) show regular gradation in physical properties such as
M.Pt, B.Pt, density etc
NOMENCLATURE Primary Word Prim. Sec. IUPAC
The most widely accepted and the latest system of naming prefix root suffix suffix name
organic compounds is IUPAC (International Union of Pure
Cyclo hex ane - Cyclohexane
and Applied Chemists) system, according to which the name
essentially consists of three parts. (b) Secondary prefix: The certain atoms and groups which
(i) Word root : It indicates the nature of the basic carbon are not considered as functional groups but are treated as
skeleton. From C1 to C4 common names have been retained substituents are called secondary prefixes. They are added
and from C5 upwards Greek number roots have been used before the word root in case of acyclic compounds and before
Chain length Word root Chain length Word root the primary prefix in case of cyclic compounds in
C1 Meth- C7 Hept- alphabetical order. The important secondary prefixes are
C2 Eth- C8 Oct- Substituent Sec. prefix
C3 Prop- C9 Non- – X (F, Cl, Br, I) Halo
C4 But- C10 Dec- −NO2 – NO Nitroso Nitro
C5 Pent- C11 Undec + ¨
Diazo
−N ≡ N
C6 Hex- C12 Dodec
– OR (R = CH3 , C2 H5 , C3 H7 , etc. ) Alkoxy
The generic word root for any carbon chain is "alk". −R(CH3 , C2 H5 , C3 H7 ,etc) Alkyl
(ii) Suffix: These are of two types
Thus the complete IUPAC name of an organic compound
(a) Primary suffix : It is added to the word root to designate consists of the following parts
saturation or unsaturation in a carbon chain Sec. prefix Prim. Prefix
Type of Carbon chain Primary Suffix Generic name word root Prim. Suffix
Saturated - ane Alkane
Unsaturated with one C = C - ene Alkene
Unsaturated with one C ≡ C - yne Alkyne
(b) Secondary suffix : It is added to indicate the functional
group present in the compound. The terminal ‘e’ is dropped, IUPAC name is 4-Bromocyclohex-2-ene-1-ol or 4
if secondary suffix begins with a vowel (a, e, i, o, u, y) but it is Bromo-2-Cyclohexenol
retained if the secondary suffix begins with a consonant. word root = hex
Functional Secondary Generic name Prime suffix = ene
group suffix Sec. suffix = ol
−OH - ol Alkanol Prime prefix = Cyclo
−CHO −al Alkanal Sec. prefix = 4 bromo
>C=O - one Alkanone ALKYL GROUPS: Univalent groups formed by the removal of
−COOH - oic acid Alkanoic acid one hydrogen atom from an alkane are known as alkyl
−COX - oyl halide Alkanoyl halide groups or alphyl groups. Their names are obtained by
−CONH2 - amide Alkanamide changing the suffix –ane of parent hydrocarbon by –yl
−COOR - alkyl ---oate Alkyl alkanoate Short-hand
Alkane Group IUPAC name
Alkanoic notation
−(CO)2 O - oic anhydride Methane Methyl CH3 − Me Methyl
anhydride Ethane ethyl C2H5 − Et Ethyl
−CN - nitrile Alkanenitrile Propane n-propyl CH3 CH2 CH2 − n − Pr , Prα or Pr 1-propyl
|
−SH - thiol Alkanethiol Iso propyl
CH3 − CH − CH3 Iso- Pr, Prβ , Pri 2-propyl
−NH2 - amine Alkanamine Butane n-butyl CH3CH2 − CH2 − CH2 − −n − Bu, Buα or Bu 1-butyl
β S 1-methyl
s-butyl CH3 CH2 − CH − CH3 s − Bu, Bu or Bu
propyl
(iii) Prefix: They are of two types
2-methyl
Iso-butyl ( CH3 ) 2CH − CH2 − Iso-Bu, or Bui
propyl
(a) Primary prefix: It is for cyclic nature of the compound 1,1-dimethyl
and primary prefix cyclo is used t-butyl (CH3)3C − t − Bu, But
ethyl
2
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, IUPAC NOMENCLATURE (Organic Chemistry)
NOMENCLATURE OF SIMPLE ALIPHATIC COMPOUNDS
Class Formula General Common IUPAC group IUPAC
formula Name Name
Alkanes or Methane
1. CH4C2H6 Cn H2n+2 Alkane Methane Ethane
paraffins Ethane
Alkenes Ethylene
2. C2 H4 C3 H6 Cn H2n Alkene Ethene propene
or Olefins Propyline
Acetylene
Alkynes C2 H2
3. Cn H2n−2 Methyl Alkyne Ethene propene
or Acetylenes C2 H4
acetylene
CH3 Cl Methyl
Alkyl Chloromethane
4. R–X chloride Haloalkanes
halides C2 H5 Cl Chloroethane
Ethyl chloride
Ethylene
Dihalogen CnH2n X 2 Chloride 1,2-dichloroethane
5. ( Alkylenehalide)
derivatives Ethylidine 1,1-dichloroethane
Chloride
Trihalogen 1,1,1-
6. CHCl 3 CnH2n−1 X3 Chloroform
derivatives trichloromethane
Tetra halogen Carbon tetra 1,1,1,1-tetra-
7. CCl 4 CnH2n−2 X4
derivatives chloride chloromethane
8. Alcohols CH3 OH CnH2n −2 OH Methyl Alkanol Methanol
(Monohydric) Alcohol
Ethylene glycol
Dihydric CnH2n(OH)2 Glycerol Ethane-1, 2-diol
Trihydric CnH2n–1(OH)3 Propane-1,2,3-
triol
9. Monocarboxylic HCOOH R–COOH Formic Acid Alkanoic acid Methanoic acid
Acids or Fatty CH3 COOH Acetic acid Ethanoic acid
acids C3 H7 ⋅ COOH Butyric acid Ethanoic acid
Dicarboxylic C4 H10 ⋅ COOH Valeric acid Pentanoic acid
acids
CnH2n(COOH)2 Malonic acid Propane-1, 3 Dioic
Succinic acid acid
acid Butane-1, 4-
dioic acid
Glutaric acid
Pentane-1,5-dioic
Adipic acid acid
oxalic acid Hexane-1,6-dioic
acid
Ethane-1,2-dioic
acid
3
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CLASSIFICATION OF ORGANIC COMPOUNDS (iv) Heterocyclic: The ring system is made up of two or
The ability of carbon to combine with large number of more than two types of atoms. They may be
elements especially O, N, S, X etc, to undergo catenation to (a) Alicyclic: e.g.
form chains of varying lengths and shapes and existence of
isomers has led to the formation of more than five million
organic compounds. These have been classified into the
following main groups
(b) Aromatic: e.g.
(i) Acyclic or open chain compounds:
For example:
CLASSIFICATION BASED ON FUNCTIONAL GROUPS
On the basis of functional groups which confer characteristi c
properties on them, the organic compounds have been
classified as follows
Class Functional group
Halides X (Cl, Br, I) Halo
(ii) Cyclic or closed chain compounds.: For example
Esters
Olefins Alkenes >C=C<
Acid halides
(iii) Homocyclic: The ring system is made up of one type of Acetylenes / Alkynes — C ≡ C—
atoms generally carbon Anhydrides
(a) Alicyclic: The cyclic compounds resembling open chain
aliphatic compounds. Alcohols — OH (Hydroxy )
For example: Cycloalkanes Amines −NH2
(b) Aromatic: The benzene, napthalene and their
derivatives etc are homocyclic aromatic compounds Aldehydes
Ketones
Sulphonic acid −SO3 H
Acids
Amides
HOMOLOGOUS SERIES A group of a particular class of
compounds where a preceeding or succeeding member
differ by one – CH2 . The members of the series are known as
homologues. The homologues
1
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, IUPAC NOMENCLATURE (Organic Chemistry)
(i) have the same general formula Cn H2n+2 or Cn H2n +1 X Primary Word Prim. Sec. IUPAC
(ii) molecular weight differing by 14 of two successive prefix root suffix suffix name
members Cyclo hex ane - Cyclohexane
(iii) can be prepared by general methods of preparation immediately before the word root. eg.
(iv) have almost similar chemical properties
(v) show regular gradation in physical properties such as
M.Pt, B.Pt, density etc
NOMENCLATURE Primary Word Prim. Sec. IUPAC
The most widely accepted and the latest system of naming prefix root suffix suffix name
organic compounds is IUPAC (International Union of Pure
Cyclo hex ane - Cyclohexane
and Applied Chemists) system, according to which the name
essentially consists of three parts. (b) Secondary prefix: The certain atoms and groups which
(i) Word root : It indicates the nature of the basic carbon are not considered as functional groups but are treated as
skeleton. From C1 to C4 common names have been retained substituents are called secondary prefixes. They are added
and from C5 upwards Greek number roots have been used before the word root in case of acyclic compounds and before
Chain length Word root Chain length Word root the primary prefix in case of cyclic compounds in
C1 Meth- C7 Hept- alphabetical order. The important secondary prefixes are
C2 Eth- C8 Oct- Substituent Sec. prefix
C3 Prop- C9 Non- – X (F, Cl, Br, I) Halo
C4 But- C10 Dec- −NO2 – NO Nitroso Nitro
C5 Pent- C11 Undec + ¨
Diazo
−N ≡ N
C6 Hex- C12 Dodec
– OR (R = CH3 , C2 H5 , C3 H7 , etc. ) Alkoxy
The generic word root for any carbon chain is "alk". −R(CH3 , C2 H5 , C3 H7 ,etc) Alkyl
(ii) Suffix: These are of two types
Thus the complete IUPAC name of an organic compound
(a) Primary suffix : It is added to the word root to designate consists of the following parts
saturation or unsaturation in a carbon chain Sec. prefix Prim. Prefix
Type of Carbon chain Primary Suffix Generic name word root Prim. Suffix
Saturated - ane Alkane
Unsaturated with one C = C - ene Alkene
Unsaturated with one C ≡ C - yne Alkyne
(b) Secondary suffix : It is added to indicate the functional
group present in the compound. The terminal ‘e’ is dropped, IUPAC name is 4-Bromocyclohex-2-ene-1-ol or 4
if secondary suffix begins with a vowel (a, e, i, o, u, y) but it is Bromo-2-Cyclohexenol
retained if the secondary suffix begins with a consonant. word root = hex
Functional Secondary Generic name Prime suffix = ene
group suffix Sec. suffix = ol
−OH - ol Alkanol Prime prefix = Cyclo
−CHO −al Alkanal Sec. prefix = 4 bromo
>C=O - one Alkanone ALKYL GROUPS: Univalent groups formed by the removal of
−COOH - oic acid Alkanoic acid one hydrogen atom from an alkane are known as alkyl
−COX - oyl halide Alkanoyl halide groups or alphyl groups. Their names are obtained by
−CONH2 - amide Alkanamide changing the suffix –ane of parent hydrocarbon by –yl
−COOR - alkyl ---oate Alkyl alkanoate Short-hand
Alkane Group IUPAC name
Alkanoic notation
−(CO)2 O - oic anhydride Methane Methyl CH3 − Me Methyl
anhydride Ethane ethyl C2H5 − Et Ethyl
−CN - nitrile Alkanenitrile Propane n-propyl CH3 CH2 CH2 − n − Pr , Prα or Pr 1-propyl
|
−SH - thiol Alkanethiol Iso propyl
CH3 − CH − CH3 Iso- Pr, Prβ , Pri 2-propyl
−NH2 - amine Alkanamine Butane n-butyl CH3CH2 − CH2 − CH2 − −n − Bu, Buα or Bu 1-butyl
β S 1-methyl
s-butyl CH3 CH2 − CH − CH3 s − Bu, Bu or Bu
propyl
(iii) Prefix: They are of two types
2-methyl
Iso-butyl ( CH3 ) 2CH − CH2 − Iso-Bu, or Bui
propyl
(a) Primary prefix: It is for cyclic nature of the compound 1,1-dimethyl
and primary prefix cyclo is used t-butyl (CH3)3C − t − Bu, But
ethyl
2
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, IUPAC NOMENCLATURE (Organic Chemistry)
NOMENCLATURE OF SIMPLE ALIPHATIC COMPOUNDS
Class Formula General Common IUPAC group IUPAC
formula Name Name
Alkanes or Methane
1. CH4C2H6 Cn H2n+2 Alkane Methane Ethane
paraffins Ethane
Alkenes Ethylene
2. C2 H4 C3 H6 Cn H2n Alkene Ethene propene
or Olefins Propyline
Acetylene
Alkynes C2 H2
3. Cn H2n−2 Methyl Alkyne Ethene propene
or Acetylenes C2 H4
acetylene
CH3 Cl Methyl
Alkyl Chloromethane
4. R–X chloride Haloalkanes
halides C2 H5 Cl Chloroethane
Ethyl chloride
Ethylene
Dihalogen CnH2n X 2 Chloride 1,2-dichloroethane
5. ( Alkylenehalide)
derivatives Ethylidine 1,1-dichloroethane
Chloride
Trihalogen 1,1,1-
6. CHCl 3 CnH2n−1 X3 Chloroform
derivatives trichloromethane
Tetra halogen Carbon tetra 1,1,1,1-tetra-
7. CCl 4 CnH2n−2 X4
derivatives chloride chloromethane
8. Alcohols CH3 OH CnH2n −2 OH Methyl Alkanol Methanol
(Monohydric) Alcohol
Ethylene glycol
Dihydric CnH2n(OH)2 Glycerol Ethane-1, 2-diol
Trihydric CnH2n–1(OH)3 Propane-1,2,3-
triol
9. Monocarboxylic HCOOH R–COOH Formic Acid Alkanoic acid Methanoic acid
Acids or Fatty CH3 COOH Acetic acid Ethanoic acid
acids C3 H7 ⋅ COOH Butyric acid Ethanoic acid
Dicarboxylic C4 H10 ⋅ COOH Valeric acid Pentanoic acid
acids
CnH2n(COOH)2 Malonic acid Propane-1, 3 Dioic
Succinic acid acid
acid Butane-1, 4-
dioic acid
Glutaric acid
Pentane-1,5-dioic
Adipic acid acid
oxalic acid Hexane-1,6-dioic
acid
Ethane-1,2-dioic
acid
3
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