8.6 Aromatic Rearrangements

A number of rearrangements occur in aromatic compounds of the type:

X is usually nitrogen or oxygen. Both intermolecular and intramolecular migrations are known.

8.6.1 Intermolecular Migration from Nitrogen to Carbon

Aniline derivatives readily proceed rearrangement on treatment with acid. First, the formation of conjugate acid of the amine takes place which then eliminates the electrophilic species that reacts at the activated ortho or para position of the aromatic ring.

8.6.1.1 N-Haloanilides (Orton Rearrangement)

Treatment of N -chloroacetanilide with hydrochloric acid affords a mixture of ortho and para -chloracetanilides in the same proportions as in the direct chlorination of acetanilide.

Mechanisms