Oxidation of alkoxyphenols. Part 26. The trimer of a 2,2′-diphenoquinone (1,1′-bicyclohexa-3,5-dienylidene-2,2′-dione)

Abstract

The blue material produced in the oxidation of 4-methoxy-3-t-butylphenol, formerly described as an intermediate in the formation of the dibenzo[d,f][1,3]dioxepin oxidation product, is shown to be 5,5′-dimethoxy-4,4′-di-t-butyl-2,2′-diphenoquinone. This quinone spontaneously condenses to a colourless trimer which, in solution in polar solvents, is shown to be in equilibrium with free radicals derived from the monomer and a dimes; that from the former regenerates the quinone. The crystal structure of the dimes has been determined as 1′-(2-hydroxy-5-methoxy-4-t-butylphenyl)-4a′,5,7′-trimethoxy-4,4′-6′-tri-t-butylspiro(cyclohexa-3,5-diene-1,9′-xanthen)-2,2′(4′aH)-dione.