LIGNIN ANALYSIS BY PERMANGANATE OXIDATION - 1 - NATIVE SPRUCE LIGNIN

Permanganate oxidation has long been used to estimate the concentratio ns of uncondensed and condensed structures in phenolic lignin fraction s. Four monomers and two dimers are normally quantified for softwood l ignins and the actual yield of each is corrected for incomplete oxidat ion. Based on the analysis of several model compounds and lignin sampl es the correction factors were refined to give a better correlation be tween the original phenolic hydroxyl (PhOH) content and the total yiel d of selected products. An alkaline CuO pretreatment was used to hydro lyze most of the interunitary ether bonds in the lignin of spruce wood meal. The PhOH content increased from 12/100 C-9 units to 69/100 C-9 u nits. A composition of approximately 55 % uncondensed guaiacyls, 18% b iphenyls and 14% beta-5 was estimated from KMnO4 oxidation of this sam ple.