Chapter 23, Problem 23.42P

Interpretation Introduction

(a)

Interpretation:

The reason for –NHCOR group of amide being activating group is to be explained.

Concept introduction:

An activating group is the group, which activates the benzene ring toward electrophilic

aromatic substitution. In general, ortho/para directors increase the rate of electrophilic aromatic substitution and are called activating groups. A substituent attached to a phenyl ring by an atom possessing a lone pair of electrons tends to be an ortho/para director. Activating groups stabilize the arenium ion intermediate by participation of lone pair on the atom of substituent in resonance.

Interpretation Introduction

(b)

Interpretation:

It is to be explained why the –NHCOR group of an amide is an activating group, but it is not as strongly activating as ${\text{NH}}_{\text{2}}$.

Concept introduction:

An activating group is the group, which activates the benzene ring toward electrophilic

aromatic substitution. In general, ortho/para directors increase the rate of electrophilic aromatic substitution and are called activating groups. A substituent attached to a phenyl ring by an atom possessing a lone pair of electrons tends to be an ortho/para director. Activating groups stabilize the arenium ion intermediate by participation of lone pair on the atom of substituent in resonance.