STUDIES ON LIGNIN AND RELATED COMPOUNDS: XIX. ALKALI LIGNIN

Abstract

Alkali lignin was prepared by the method of Mehta (6). It was separated into two fractions, termed Alkali Lignin A, insoluble in dioxane-ether, and Alkali Lignin B, soluble in dioxane-ether. Both compounds were acetylated, partially methylated with diazomethane and fully methylated using dimethyl sulphate and sodium hydroxide. Treatment of both alkali lignins with phenol, using hydrogen chloride as catalyst, yielded phenol condensation products. Phenol Alkali Lignin A was acetylated, partially methylated with diazomethane and completely methylated with dimethyl sulphate and sodium hydroxide. It was found that one mole of Alkali Lignin A reacted with two moles of phenol. Alkali Lignin B yielded two phenol derivatives, an ether-insoluble and an ether-soluble product, which differ in the number of attached phenol groups. p-Bromphenol and o-bromphenol were also shown to react with Alkali Lignin A giving lignin derivatives having identical methoxyl and bromine content. On treatment of Alkali Lignin A with anhydrous methyl alcohol and hydrogen chloride a product with a higher methoxyl content was obtained, indicating the presence of hydroxyl groups capable of methylation with this reagent. From the analytical data of the different compounds some theoretical conclusions are drawn, and empirical formulas derived.