DIRECTIVE INFLUENCE OF AMINO GROUP IN ELECTROPHILIC AROMATIC SUBSTITUTION

Abstract

This chapter explains why an amino group, be it primary, secondary, or tertiary, attached to an aromatic nucleus, directs the electrophilic attack of various reagents to the ortho- and para-positions. The amino group is one of the strong ortho-para directing substituents on a benzene nucleus, but the quaternary ammonium ions attached to a benzene nucleus are meta-directing. The substituted amino group and the primary amino group head the list of ortho-para directing groups when arranged in order of their potency in this direction, and the acetylation of a primary amino group to form an amide function does not lower this efficacy markedly. One can get an idea of the relative potency of the amino group toward other groups in their ortho-para-directing influence by studying the behavior of a disubstituted benzene that has both groups present. The position ortho- to one is meta- to the other and thus, one can see as to which product preponderates and this affords a measure of the relative potency of the groups.