Process for producing 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide.

摘要

A process for producing 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide (crystal violet lactone) comprises oxidizing 2-{4,4'-bis-(dimethylamino)-benzhydryl]-5-dimethylaminobenzoic acid in an aqueous solution of a mineral acid having a pH of from 2.0 to 4.0 with air, oxygen or a gas containing oxygen in the presence of at least one catalyst selected from compounds of iron, copper, cobalt, nickel, chromium, vanadium and manganese.