In order to investigate the properties of lignin in soda pulp waste liquor, Larix wood previously digested by 6% NaOH solution was isolated into PAL (pure alkali lignin). LAL (Larix alkali lignin=PAL) fractionated with organic solvents was investigated by gel filtration with CPG-10, dioxane-H2O (1 : 1) being used as eluent. Also, these lignin fractions were analzsed mainly by IR, UV, NMR, elemental analysis, - OMe and air oxidation.
In the case of the LAL fractionated by organic solvents, results obtained were as follow : (1) Remarkable change in gel filtration, IR spectrum, and NMR spectrum patterns were shown in ether-soluble fraction. (2) The value for the weight average molecular weight calculated from gel filtration data for water-insoluble and ether-insoluble fraction, comprising more than 82% of the substance, seems to be for water-insoluble fraction about 73, 000 and ether-soluble fraction about 22, 000. (3) The change in the amount of air oxidation products of each fraction except ether-soluble fraction was scarcely observed.