Structures of two alkaline autoxidation products of BHA, a widely used antioxidant

In order to confirm the structures of the autoxidation products of 2-tert-b utyl-4-methoxyphenol (BHA), X-ray crystallographic analyses have been under taken. One of the products was converted to a dibenzoate, which was subject ed to the analysis to establish the structure as the O-6,O-7-dibenzoyl deri vative of (1R*,2R*,6S*,7S*,9R*)-4,9-di-tert-butyl-6,7-dihydroxytricyclo[5.2 .2.0(2, 6)] undec-4-ene-3,8,10-trione. Crystallographic analysis of the maj or isomer of the two isomeric products gave its structure as (E)-4-tert-but yl-2-(3-tert-butyl-4-oxocyclopent-2-en-1-ylidene)cyclopent-4-ene-1,3-dione which also established the structure of the minor isomer as the correspondi ng (Z)-isomer.