Lignin sulfonates obtained through sulfonation of Western Hemlock wood chips (W), and also lignin sulfonates prepared from milled wood lignin (MWL), were fractionated by Sephadex gel chromatography in aqueous solution and then acetylated and methylated. The resulting acetyl lignin sulfonate methyl ester (ALSME) fractions were characterized by nuclear magnetic resonance spectroscopy carried out in deuteriochloroform solutions, and the usefulness of this procedure was established. The ALSME-MWL fractions were also characterized by chemical analyses. Mass spectroscopy did not yield useful results. The findings are interpreted in relation to the structure of lignin sulfonates. Gel permeation chromatography of ALSME fractions was carried out in methanol on Sephadex LH-20 and yielded further evidence indicating the separation in part of low molecular weight ALSME species including one which was obtained in crystalline form.

Eight monomeric and seven dimeric lignin-like sulfonates were synthesized. The methods of Gellerstedt and Gierer were used to acetylate hydroxyl and to esterify sulfonic acid groupings in order to cover these polar configurations. The resultant derivatives normally were purified by recrystallization from organic solvents and were studied with respect to the chemical shift of their respective protons in nmr spectroscopy, and with respect to fragmentation patterns in mass spectroscopy. The ranges of values of protons in lignin-like sulfonate preparations were compared to those for unsulfonated preparations. In mass spectroscopy, all compounds exhibited peaks for the parent ions in the range of 1-64% abundance relative to the base which was taken to be the most abundant peak. Acetyl, sulfonate, and ether groups proved to be main targets of fragmentation and tended to be eliminated upon electron impact. Cleavage of carbon-carbon bonds was mainly observed for three-carbonside-chain ß-aryl ethers. The general fragmentation pathways have been discussed. In general, the feasibility of application of nmr and mass spectroscopy in structural studies of sulfonated lignin-like model compounds after covering the polar sulfonic acid and hydroxyl groups is demonstrated.