Chapter 23, Problem 23.4YT

Interpretation Introduction

Interpretation:

All of the atoms in Equations 23-4 and 23-5 that do not have an octet are to be identified.

Concept introduction:

The substituent on the benzene ring prior to substitution dictates the regiochemistry of the reaction. Some substituents are designated as ortho/para directors because they lead to product mixtures consisting primarily of the ortho- and para-disubstituted products. Other substituents are designated as meta directors because they favor the formation of the meta-disubstituted product. There are two kinds of ortho/para directors: (1) groups attached by an atom having at least one lone pair of electrons and (2) alkyl groups. When either of these groups is attached to benzene, the ortho and para arenium ion intermediates are lower in energy than the meta intermediate.