Formation of 3-Guaiacylbenzanthrone by the Reaction of Reduced Forms of Anthraquinone with Quinone Methides

Anthrahydroquinone and anthrone readily react with stabilised quinone methides in alkaline solution to give 10-substituted oxan thrones and an thrones respectively. Similarly, reaction of a vinyl-substituted quinone methide gives the corresponding anthrone, both as the keto and enol adducts, and the substituted oxanthrone. Whilst both forms of the substituted anthrone can be partially converted to 3-arylbenzanthronea analogous to 3-guaiacylbenzanthrone formed during pulping, the oxanthrone adduct affords practically none of thi3 product. This indicates that it is reduction of anthraquinone to its anthrone oxidation state which results in benzanthrone formation during pulping.