Glycosidic Methoxyl Groups in Methanolyzed Cellulose

Oxidation by a glycol-cleavage reagent has proved that the acid-labile methoxyl groups in methanolyzed cellulose are linked in glycosidic combination (1 per molecule), and not in an acetal structure, which would require 2 such groups per molecule. Evidence confirming the glycosidic structure was obtained by fractionating methanolyzed cellulose to the point where number- average molecular weights must be calculated on the basis of 1 methoxyl group per molecule. The rate of removal of methoxyl groups from methanolyzed cellulose upon acid hydrolysis was reinvestigated. The rate is roughly comparable to the rate of hydrolysis of methyl gluco pyranosides. These findings contradict the basis for a claim, based on copper-number deter minations, that the methoxyl groups of methanolyzed cellulose are very rapidly hydrolyzed and are of the acetal type.