Comparative Studies of Brown Coal and Lignin. II. The Action of Concentrated Alkali at Elevated Temperatures

Abstract

A study was made of the products formed by treating brown coal or lignin with concentrated aqueous or ethanolic alkali at 200 °C. With brown coals a major redistribution of the oxygen-containing functional groups appeared to occur, because the products contained aliphatically linked carboxyl groups and aliphatic hydroxyl, as well as phenolic hydroxyl groups. The behaviour of lignin under the same conditions was less clear but sufficiently similar to that of brown coal to suggest that reactions of the same type were occurring in both cases. Reactions involving decarboxylation, ring scission of dihydric phenol structures, and subsequent hydrogenation are suggested tentatively as the main steps in the formation of the products. The results provide some additional evidence for the view that there is a simple chemical relation between Victorian brown coal and lignin.