Chemistry Reference
In-Depth Information
AROMATIC ORGANIC CHEMISTRY
S
B
UBSTITUTED
ENZENES
When one hydrogen is replaced in an aromatic compound such as ben-
zene, it is called mono-substitution.
Cl
NO
2
Cl
2
HNO
3
HCl
+
+
H
2
O
chlorobenzene
nitrobenzene
H
2
SO
4
SO
3
H
+
H
2
O
benzene sulfonic acid
In most cases, the mono-substituted compounds are named as derivatives of
benzene.
Replacement of a hydrogen of benzene by chlorine is termed
chlorination
.
When one or more hydrogens are replaced by an “
−
NO
” (nitro group), it
2
is called
nitration
. Reaction of benzene with sulfuric acid, a reaction known
as
, leads to a sulfonic acid. Note that in each substitution reaction,
a small hydrogen-containing compound is formed.
An organic compound can be both aromatic and aliphatic; that is, one or
more of the hydrogens of a benzene ring can be replaced by an aliphatic
group. Such compounds are always classified as being aromatic.
sulfonation
