Chapter 16.SE, Problem 66AP

Interpretation Introduction

Interpretation:

Given that phenylboronic acid upon nitration gives 15% orthosubstitution product and 85% meta product. The meta directing effect of the –B(OH)₂ group is to be explained.

Concept introduction:

The substituents attached to the ring have a strong influence on the incoming electrophile. Electron releasing substituent groups, except halogens, activate the ring and direct the incoming electrophile to the o- and p- positions. Halogens are o- and p- directors but they deactivate the ring. Electron withdrawing substituent groups deactivate the ring and direct the incoming electrophile to the m- position. Boron compounds are usually electron acceptors as in these compounds boron is electron deficient.

To explain:

The meta directing effect of the –B(OH)₂ group as upon nitrating phenylboronic acid 15% orthosubstitution product and 85% meta product are obtained.