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Hydrogen fluoride saccharification of wood: Lignin fluoride content, isolation of α‐ D ‐glucopyranosyl fluoride and posthydrolysis of reversion products
Author(s) -
Hardt Haim,
Lamport Derek T. A.
Publication year - 1982
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260240412
Subject(s) - chemistry , fluoride , anhydrous , lignin , hydrogen fluoride , solvolysis , hydrolysis , cellulose , organic chemistry , nuclear chemistry , inorganic chemistry
Wood chips from bigtooth aspen ( Populus grandidentata Michx.) were saccharified by reaction with liquid hydrogen fluoride either anhydrous or containing up to 10% v/v water. The reaction products were separated into a solid lignin fraction and a water‐soluble saccharide fraction. The fluoride content of the lignin (determined after alkaline fusion) was initially about 1 mg/g wood, but was lowered to 0.1 mg/g wood by grinding and washing. Thus little or no chemical binding of fluoride to lignin occurred during hydrogen fluoride (HF) solvolysis. Analysis of the water‐soluble fraction by gel filtration on Biogel P2 columns showed a range of low‐molecular‐weight oligosaccharides and only 10–20% sugar monomers. Thus considerable reversion occurred during HF evacuation. Posthydrolysis conditions were optimized for these reversion products by varying temperature and acid concentration. Optimal conditions at 1 h were 140°C with 100m N sulfuric acid or 225m N Hydrofluoric acid resulting in monomer yields of > 90% for 0.5% sugar solutions and > 80% for 10% sugar solutions. After reaction of pure cellulose (Filter paper) with hydrogen fluoride in the absence of water, and terminating the reaction with calcium carbonate, the reaction intermediate α‐ D ‐glucopyranosylfluoride was isolated with a maximal yield of 0.2 g/g paper. Upon purification via paper chromatography glucosylfluoride was identified by its specific rotation and also by gas chromatography‐mass spectrometry of its tetra‐ O ‐trimethylsilyl derivative.