VAPOR-PHASE HF SOLVOLYSIS OF CELLULOSE - MODIFICATION OF THE REVERSION OLIGOSACCHARIDE DISTRIBUTION BY IN-SITU METHANOLYSIS

The solvolysis of cellulose by anhydrous hydrogen fluoride (HF) vapor produces water-soluble oligosaccharides generated by repolymerization of the primary solvolysis product, glucosyl fluoride. In-situ methanol ysis of glucosyl fluoride in the HF-reacting cellulose substrate reduc ed the extent of this reversion reaction and increased the recovery of monomers (as glucose and 1-0-methyl glucose) in the water-soluble rea ction products. Single cellulose filter paper wafers both with and wit hout absorbed methanol were reacted with an HF vapor stream at 30-degr ees-C and 1.0 atm for reaction times varying from 2 to 12 min. The oli gosaccharide product distribution in the water-soluble reaction produc ts was then profiled by HPLC. The cellulose substrate was completely c onverted to water-soluble products within 4 min exposure to HF vapor, but the oligosaccharide product distribution did not reach equilibrium until 10 min exposure to HF vapor. Absorbed methanol (5 mole methanol to 1 mole glucan) in the cellulose substrate increased the monomer re covery of the water-soluble reaction products from 30 mole % to 60 mol e %.