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Synthesis and Structure of Alcohols
Alcohols can be considered organic analogues of water.
H O H

R O H

Alcohols are usually classified as primary, secondary and tertiary.
H
R

H
OH

H primary R

R
OH

R

R

OH

OH

R

secondary

tertiary

phenol

Alcohols with the hydroxyl bound directly to an aromatic (benzene) ring are called phenols.
Nomenclature of Alcohols
(Normally any compound’s name which ends in –ol is an alcohol of some sort) IUPAC rules that:
(1) Name the longest carbon chain bearing the –OH group. Drop the last –e from the alkane name and add –ol to obtain the root name.
(2) Number the longest chain starting at the end nearest the –OH group, and designate a number for the –OH group. (Hydroxyl has greater priority than carbon-carbon multiple bonds).
(3) Name the remaining substituents and their numbers as for alkanes and alkenes. CH3 OH
H3C

CH2-Cl
CH3 H

1-chloro-3,3-dimethyl-2-butanol

Ch10 Alcohols (Str and Syn).doc

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(4) Cyclic alcohols have the prefix cyclo-, and the hydroxyl group is deemed to be on C-1.
HO CH2CH3

1-ethylcyclopropanol

(5) Alcohols with double or triple bonds are named using the –ol suffix on the alkene or alkyne name. Numbering gives the hydroxyl group the lowest possible number. When numbers are also given for the multiple bond position, the position of the hydroxyl can be written immediately before the –ol prefix.
OH
H3C

Cl
H

H

(Z)-4-chloro-3-buten-2-ol

(6) If the hydroxyl group is only a minor part of the structure, it may be named as a hydroxy- substituent.
OH
CO2H
3-hydroxybutanoic acid

Nomenclature of Diols (Gycols)
Diols are compounds with two hydroxyl groups.
They are named as for alcohols except the suffix –diol is used and two numbers are required to locate the –OH’s.
OH

OH

1-cyclohexyl-1,3-butanediol

Ch10 Alcohols (Str and Syn).doc

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Nomenclature of Phenols
A phenol always involves a benzene