INFRARED SPECTROSCOPIC ANALYSIS OF THE STRUCTURE OF XYLANS

Structural features of a number of xylan types (Sigma, Fluka) and that extracted by us from birch wood (BW) have been determined using IR transmission spectroscopy and elemental analysis. The calculated molecular formulas of Sigma and Fluka xylans are close to the theoretical molecular formula of a xylopyranose residue whereas the molecular formula of BW xylan differs from it. The investigated xylan samples contain both acetyl and methoxyl groups in small amounts. A somewhat higher content of acetyl groups is found in BW xylan compared to that in Sigma and Fluka xylans and it practically does not contain traces of lignin and phenolic alcohols whereas Sigma xylan includes large traces of lignin and glucuronic acids. IR spectra of the investigated samples suggest that the studied types of xylan have an identical system of hydrogen bonds.