A. Halogen and Nitro- Substituted Aromatics 24
NOMENCLATURE IN ORGANIC CHEMISTRY B. Carboxylic Acids and Derivatives 24
C. Phenols and Thiophenols 25
Contents D. Aldehydes and Ketones 26
1. INTRODUCTION 3 E. Sulfonic acids and Sulfonic Acid Derivatives 27
2. HYDROCARBONS 3 F. Aromatic Amines 28
(i) Alkanes 3 G. Diazonium Salts 29
A. Unbranched Chains 3 6. RADICOFUNCTIONAL NAMING 29
B. Unbranched chains 4 A. Alkyl Halides 29
(ii) Alkenes 5 B. Alcohols 29
A. One double bond 5 C. Ketones 30
B. More than one double bond 5 D. Nitriles (or Cyanides) 30
C. E/Z Isomers in Alkenes 6 E. Grignard Reagents 30
(iii) Alkynes 8
(iv) Combined Alkenes and Alkynes 8
(v) Cyclic Hydrocarbons 9
3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS 10
4. COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES 12
(i) General Naming Scheme 12
A. Choosing the Principal Chain 13
B. Naming the Principal Chain 13
C. Numbering the Principal Chain 13
(ii) Naming Various Classes of Organic Compounds 14
A. Ethers and Thioethers 14
B. Alcohols and Thiols 14
C. Acids, Salts of Acids and Acid Anhydrides 15
D. Esters 17
E. Acid Halides 18
F. Amides 18
G. Nitriles 19
H. Aldehydes 19
I. Ketones 21
J. Amines and Ammonium Salts 22 Revised and updated
5. AROMATIC COMPOUNDS 23 Professor L D Field
(i) General Notes 23 May 2004
(ii) Aromatic Hydrocarbons 23
(iii) Substituted Aromatic Hydrocarbons 24
1 2
, B. Branched Chains
NOMENCLATURE IN ORGANIC CHEMISTRY The following steps are taken in naming an alkane with a branched chain:
(a) Find the longest continuous carbon chain and select the appropriate alkane name
1. INTRODUCTION from Table 1. (Side chains are not included in the carbon count.)
It is important that organic compounds are corrrectly and unambiguously named so that there (b) Name all of the side chains (carbon chains attached to the longest chain) and list
can be absolutely no confusion about what compounds are actually being reported or them in alphabetical order. Ignore multiplicative prefixes such as “di-“ (2), “tri-“
described. There have been many conventions for naming organic compounds - some have (3), "tetra-" (4) etc. Also ignore "sec-" and "tert-" but not "iso".
had limit scope or become embedded in common usage and some have persisted over time
(c) Number the longest chain so that substituents have the lowest possible numbers
The International Union of Pure and Applied Chemistry (I.U.P.A.C.) periodically reviews and insert location numbers before each of the side chain names.
naming practice, attempting to standardise nomenclature. The following guidelines for
organic nomenclature are based on the definitive rules published by I.U.P.A.C.1 (the Special Note: The following groups have the special names indicated:
International Union of Pure and Applied Chemistry).
CH 3 CH3
2. HYDROCARBONS isopropyl isobutyl
CH CH CH2
(i) The Alkanes (CnH2n+2)
CH3 CH3
A. Unbranched Chains
The first four (n=1-4) unbranched chain saturated hydrocarbons are called methane, ethane, CH 3 secondary-butyl CH3 tertiary-butyl
propane and butane. After this, there is a numerical term (of Greek origin) followed by the sec-butyl tert-butyl
ending "-ane". The first twelve members are given in Table 1. CH CH3 C
s-butyl t-butyl
Table 1. The names of the first 12 linear alkanes CH 3 CH3
n Name Molecular formula Constitutional formula
CH3
1 methane CH4 CH4
2 ethane C2H6 CH3CH3
3 propane C3H8 CH3CH2CH3 Examples
4 butane C4H10 CH3CH2CH2CH3 CH3 CH2 CH CH2 CH3 3-methylpentane
5 pentane C5H12 CH3CH2CH2CH2CH3 CH3
6 hexane C6H14 CH3CH2CH2CH2CH2CH3
CH3 CH CH2 CH CH CH2 CH3 2,4,5-trimethylheptane
7 heptane C7H16 CH3CH2CH2CH2CH2CH2CH3
(not 3,4,6-)
8 octane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 CH3 CH3 CH3
9 nonane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3 CH3
10 decane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 4-isopropyl-2,2-dimethylheptane
CH3 CH2 CH2 CH CH2 CH CH3
11 undecane C11H24 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3
CH CH3
12 dodecane C12H26 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 CH3 CH3
CH3 CH2 4-ethyl-5-methyloctane
The group derived from one of these alkanes by removal of a terminal (end) hydrogen is
(not 5-ethyl-4-methyloctane)
called an alkyl group. The group name is found by removing "ane" from the alkane name CH3 CH2 CH2 CH CH CH2 CH2 CH3
and adding "yl".
CH3
Example: CH3-CH2-CH2-CH3 butane
becomes CH3-CH2-CH2-CH2- butyl
Note: The free valence must be on the terminal carbon.
1
I.U.P.A.C. Nomenclature for Organic Chemistry, Sections A, B and C (combined edition),
Butterworths Scientific Publications, London, 1971.
3 4
NOMENCLATURE IN ORGANIC CHEMISTRY B. Carboxylic Acids and Derivatives 24
C. Phenols and Thiophenols 25
Contents D. Aldehydes and Ketones 26
1. INTRODUCTION 3 E. Sulfonic acids and Sulfonic Acid Derivatives 27
2. HYDROCARBONS 3 F. Aromatic Amines 28
(i) Alkanes 3 G. Diazonium Salts 29
A. Unbranched Chains 3 6. RADICOFUNCTIONAL NAMING 29
B. Unbranched chains 4 A. Alkyl Halides 29
(ii) Alkenes 5 B. Alcohols 29
A. One double bond 5 C. Ketones 30
B. More than one double bond 5 D. Nitriles (or Cyanides) 30
C. E/Z Isomers in Alkenes 6 E. Grignard Reagents 30
(iii) Alkynes 8
(iv) Combined Alkenes and Alkynes 8
(v) Cyclic Hydrocarbons 9
3. COMPOUNDS CONTAINING HALOGENS AND NITRO GROUPS 10
4. COMPOUNDS WITH FUNCTIONAL GROUPS NAMED AS SUFFIXES 12
(i) General Naming Scheme 12
A. Choosing the Principal Chain 13
B. Naming the Principal Chain 13
C. Numbering the Principal Chain 13
(ii) Naming Various Classes of Organic Compounds 14
A. Ethers and Thioethers 14
B. Alcohols and Thiols 14
C. Acids, Salts of Acids and Acid Anhydrides 15
D. Esters 17
E. Acid Halides 18
F. Amides 18
G. Nitriles 19
H. Aldehydes 19
I. Ketones 21
J. Amines and Ammonium Salts 22 Revised and updated
5. AROMATIC COMPOUNDS 23 Professor L D Field
(i) General Notes 23 May 2004
(ii) Aromatic Hydrocarbons 23
(iii) Substituted Aromatic Hydrocarbons 24
1 2
, B. Branched Chains
NOMENCLATURE IN ORGANIC CHEMISTRY The following steps are taken in naming an alkane with a branched chain:
(a) Find the longest continuous carbon chain and select the appropriate alkane name
1. INTRODUCTION from Table 1. (Side chains are not included in the carbon count.)
It is important that organic compounds are corrrectly and unambiguously named so that there (b) Name all of the side chains (carbon chains attached to the longest chain) and list
can be absolutely no confusion about what compounds are actually being reported or them in alphabetical order. Ignore multiplicative prefixes such as “di-“ (2), “tri-“
described. There have been many conventions for naming organic compounds - some have (3), "tetra-" (4) etc. Also ignore "sec-" and "tert-" but not "iso".
had limit scope or become embedded in common usage and some have persisted over time
(c) Number the longest chain so that substituents have the lowest possible numbers
The International Union of Pure and Applied Chemistry (I.U.P.A.C.) periodically reviews and insert location numbers before each of the side chain names.
naming practice, attempting to standardise nomenclature. The following guidelines for
organic nomenclature are based on the definitive rules published by I.U.P.A.C.1 (the Special Note: The following groups have the special names indicated:
International Union of Pure and Applied Chemistry).
CH 3 CH3
2. HYDROCARBONS isopropyl isobutyl
CH CH CH2
(i) The Alkanes (CnH2n+2)
CH3 CH3
A. Unbranched Chains
The first four (n=1-4) unbranched chain saturated hydrocarbons are called methane, ethane, CH 3 secondary-butyl CH3 tertiary-butyl
propane and butane. After this, there is a numerical term (of Greek origin) followed by the sec-butyl tert-butyl
ending "-ane". The first twelve members are given in Table 1. CH CH3 C
s-butyl t-butyl
Table 1. The names of the first 12 linear alkanes CH 3 CH3
n Name Molecular formula Constitutional formula
CH3
1 methane CH4 CH4
2 ethane C2H6 CH3CH3
3 propane C3H8 CH3CH2CH3 Examples
4 butane C4H10 CH3CH2CH2CH3 CH3 CH2 CH CH2 CH3 3-methylpentane
5 pentane C5H12 CH3CH2CH2CH2CH3 CH3
6 hexane C6H14 CH3CH2CH2CH2CH2CH3
CH3 CH CH2 CH CH CH2 CH3 2,4,5-trimethylheptane
7 heptane C7H16 CH3CH2CH2CH2CH2CH2CH3
(not 3,4,6-)
8 octane C8H18 CH3CH2CH2CH2CH2CH2CH2CH3 CH3 CH3 CH3
9 nonane C9H20 CH3CH2CH2CH2CH2CH2CH2CH2CH3 CH3
10 decane C10H22 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH3 4-isopropyl-2,2-dimethylheptane
CH3 CH2 CH2 CH CH2 CH CH3
11 undecane C11H24 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3
CH CH3
12 dodecane C12H26 CH3CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH3 CH3 CH3
CH3 CH2 4-ethyl-5-methyloctane
The group derived from one of these alkanes by removal of a terminal (end) hydrogen is
(not 5-ethyl-4-methyloctane)
called an alkyl group. The group name is found by removing "ane" from the alkane name CH3 CH2 CH2 CH CH CH2 CH2 CH3
and adding "yl".
CH3
Example: CH3-CH2-CH2-CH3 butane
becomes CH3-CH2-CH2-CH2- butyl
Note: The free valence must be on the terminal carbon.
1
I.U.P.A.C. Nomenclature for Organic Chemistry, Sections A, B and C (combined edition),
Butterworths Scientific Publications, London, 1971.
3 4
