Photochemical production of quinoid structures in wood

Abstract

DEGRADATION of wood by a number of agencies (for example, white rot fungi1, hot alkaline sulphite2 or light3) results in a decrease in the methoxyl content of the lignin. Thus after irradiation for 1,000 h using an enclosed 1 kW carbon arc, glass-covered newspaper manufactured predominantly from Pinus radiata seemed to have lost about one-third of its methoxyl groups. Such a high loss suggests that, despite the very complex and variable type of structure proposed for lignin4, a fairly simple molecular unit, which can be formed from at least 30 per cent of the lignin building stones, is involved. Evidence is presented here which indicates that this intermediate is of quinoid structure; either an o-quinone, a p-quinone, or a p-quinone methide. © 1968 Nature Publishing Group.