CH 2 Br
C N
CH 2 OH
CH 2 CN
CH 2 NH 3 Br
CH 2 NH 2
Bromomethylbenzene
HO −
Benzylalcohol
Phenylacetonitrile
+
_
−
:NH 3
Benzylamine
HO −
4.6.10 Phenols
Phenols are compounds of the general formula ArOH, where Ar is a phenyl,
a substituted phenyl, or one of the other aryl groups, e.g. naphthyl. Phenols
differ from alcohols in having the À ÀOH group attached directly to an
aromatic ring. Hydroxybenzene, the simplest member of the phenols, is
generally referred to as phenol.
OH
CH 2 OH
Phenol
−OH is directly linked
to the aromatic ring carbon
Benzylalcohol
−OH is not directly linked
to the aromatic ring carbon
Many pharmaceutically and pharmacologically important compounds,
either of natural or synthetic origin, belong to this class of compounds,
e.g. salicylic acid and quercetin.
OH
CO 2 H
O
O
OH
O
H
OH
OH
OH
Salicylic acid
An analgesic, and a precusor
for aspirin
Quercetin
A natural antioxidant
Nomenclature of phenols
Phenols are generally named as derivatives of the simplest member of the
family, phenol, e.g. o-chlorophenol. Sometimes trivial or special names are
also used, e.g. m-cresol. Occasionally, phenols are named as hydroxycompounds, e.g. para-hydroxybenzoic acid. Numbering is often used to
denote the position(s) of the substituent(s) on a phenol skeleton, e.g. 2,4dinitrophenol.
4.6 AROMATIC COMPOUNDS AND THEIR DERIVATIVES
129