THE CARBONYL GROUP IN BIRCH LIGNIN

Abstract

When lignin is extracted from birch wood with acetic acid its behavior differs from that of lignin extracted with acetic acid and then boiled with formic acid. There is less hydroxyl lost per methoxyl gained when the lignin treated with formic acid is methylated with diazomethane. An increase in addition of Grignard reagent also corresponds to this increase in methoxyl. This indicates that a lactone linkage is present in extracted lignin but probably not in lignin in the wood, because the effect is less noticeable in lignin more mildly extracted by acetic acid. In dimethyl sulphate – alkali-methylated lignins, where the lactone would no longer be present there is evidence of a carboxyl group which can be diazomethane-methylated and the resulting ester saponified at will.