Separation of cellulose/hemicellulose from lignin in white pine sawdust using boron trihalide reagents

A mild method for the separation of cellulose/hemicellulose from extractives free sawdust is described. Sequential treatments with an equimolar mixture of BCl₃ and BBr₃ remove polysaccharide components from a white pine sawdust sample. Spectroscopic analyses, including solution and solid-state NMR spectroscopy, confirm a reduction in the amount of aliphatic sugars in solid samples and show that extracted components consist only of polymeric sugars and are free of aromatics. Staining with fluorescent and colorimetric dyes confirm that the sawdust sample after boron trihalide treatment is primarily lignin, with no detectable polysaccharides.