DETERMINATION OF SUBSTITUENT DISTRIBUTION OF DMSO-SOLUBLE PORTION OF ACETYLATED WOOD MEAL BY C-13-NMR SPECTROSCOPY

Makamba (Betula maximowiczii Regel) wood meal was acetylated with a mi xture of benzenetrifluoroacetic anhydride-acetic acid or with acetic a nhydride alone. The acetylated wood meal was ground and dissolved in D MSO (dimethyl sulfoxide). The soluble portions were analyzed by C-12-N MR spectroscopy using DMSO-d6 as a solvent at 80-degrees-C. Signals we re assigned based on the spectra of acetylated xylan and cellulose ace tate. The hydroxyl group at the C2 carbon of the xylan was substituted easily by an acetyl group with a small weight gain; whereas, the subs titution of the hydroxyl groups at the C3 carbon of the xylan and the C2, C3, and C6 carbons of the cellulose increased with increasing weig ht gains. At the small weight gain, the mono- and di-substitutions mai nly occurred. The proportion of tri-substitution increased with increa ses of weight gains. The substituent distributions were similar for th e two acetylation methods.