( viii ) Electrophihc substitution reactions Aniline is ortho and para directing towards electrophilic substitution reaction due to high electron density at ortho and para-positions .
To prepare monosubstituted derivative , activating effect of -NH2 group must be controlled . It can be done by protecting the -NH2 group by acetylation with acetic anhydride .
( b ) Nitration Direct nitration of aniline is not possible as it is susceptible to oxidation , thus amino group is first protected by acetylation .