1,5-Anhydro-beta-L-arabinofuranose from pyrolysis of plant cell wall materials (biomass)

Three types of agricultural waste material having a significant content of L-arabinose have been subjected to mild, vacuum pyrolysis, and yields of 1,5-anhydro-L-arabinofuranose (1) determined. In corn bran, approximately 40% of the L-arabinose is converted into 1, and this conversion is increased to 78% when the bran is subjected to prior acid washing. The inner and outer barks of ponderosa pine give approximately 30% conversion of their L-arabinose content into 1, but orange peel gives only 9% conversion. A mechanism is postulated involving pyrolytic scission of pendant L-arabinofuranose units from polysaccharides, with cyclization to produce 1.