Alcohol Nomenclature
In the IUPAC system of nomenclature, functional groups are normally
designated in one of two ways. The presence of the function may be indicated by
a characteristic suffix and a location number. This is common for the
carbon-carbon double and triple bonds which have the respective suffixes ene
and yne. Halogens, on the other hand, do not have a suffix and are named
as substituents, for example: (CH3)2C=CHCHClCH3
is 4-chloro-2-methyl-2-pentene. If you are uncertain about the IUPAC rules for
nomenclature you should review them now.
Alcohols are usually named by the first procedure and are designated by an ol suffix, as in ethanol, CH3CH2OH (note that a locator number is not needed on a two-carbon chain). On longer chains the location of the hydroxyl group determines chain numbering. For example: (CH3)2C=CHCH(OH)CH3 is 4-methyl-3-penten-2-ol. Other examples of IUPAC nomenclature are shown below, together with the common names often used for some of the simpler compounds. For the mono-functional alcohols, this common system consists of naming the alkyl group followed by the word alcohol. Alcohols may also be classified as primary, 1º, secondary, 2º & tertiary, 3º, in the same manner as alkyl halides. This terminology refers to alkyl substitution of the carbon atom bearing the hydroxyl group (colored blue in the illustration).
Alcohols are usually named by the first procedure and are designated by an ol suffix, as in ethanol, CH3CH2OH (note that a locator number is not needed on a two-carbon chain). On longer chains the location of the hydroxyl group determines chain numbering. For example: (CH3)2C=CHCH(OH)CH3 is 4-methyl-3-penten-2-ol. Other examples of IUPAC nomenclature are shown below, together with the common names often used for some of the simpler compounds. For the mono-functional alcohols, this common system consists of naming the alkyl group followed by the word alcohol. Alcohols may also be classified as primary, 1º, secondary, 2º & tertiary, 3º, in the same manner as alkyl halides. This terminology refers to alkyl substitution of the carbon atom bearing the hydroxyl group (colored blue in the illustration).
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