Chapter 16.SE, Problem 52AP

Interpretation Introduction

Interpretation:

The aromatic compounds bromobenzene, toluene, phenol, aniline, nitrobenzene and p-bromotoluene are to be ranked in the expected order of their reactivity towards Friedal-Crafts alkylation. Which of them are unreactive is also to be stated.

Concept introduction:

Aromatic compounds that contain an ortho and para directing substituent groups (except halogens) are more reactive than benzene and that contain a meta directing substituent group are less reactive than benzene. Halogens are ortho & para directing yet deactivating groups. Hence the halogen substituted benzenes are less reactive than benzene.

As an exception, the aromatic rings that are either substituted by a strongly electron-withdrawing groups such as carbonyl or basic amino group that can be protonated do not react in Friedal crafts reaction, as they deactivate the ring.

To rank:

The aromatic compounds bromobenzene, toluene, phenol, aniline, nitrobenzene and p-bromotoluene in the expected order of their reactivity towards Friedal-Crafts alkylation. Further to state which of them are unreactive.