Benzoic Acid → Phthalide

Participants

Reaction Steps

A benzoic acid derivative of formula 1 is reacted with formaldehyde under acidic conditions to yield a phthalide derivative of formula 2. ##STR4## The phthalide derivative is then brominated with any suitable brominating agent, e.g. N-bromosuccinimide to yield an unstable bromophthalide derivative, 3, which is readily reacted with water to a phthalaldehydic acid derivative, 4. ##STR5## The phthalaldehydic acid derivative may then be oxidized to the desired phthalic anhydride derivative, 5, in good yield using a suitable oxidizing agent such as manganese dioxide. ##STR6##

Provenance & Evidence