Sugar polyether polyols for rigid polyurethanes—propoxylation of disaccharides under alkaline condition

The propoxylation of lactose (a dairy waste by-product), under basic conditions, yields polyether polyols that have been found to be a good substitute for sucrose polyether polyols currently used in the rigid polyurethane foam industry. ¹³C-NMR analysis of polyethers of sugars indicate that while the disaccharide α (1 → 2′) linkage of sucrose remains intact during propoxylation, that of lactose breaks, giving polyethers of monosaccharides. In addition, IR spectra reveal the absence of unsaturation in the product. The presence of multiplicities of the different carbon peaks of propylene oxide in the NMR spectrum of the product implies a regioselective attack on the C-1 or C-2 of propylene oxide by the incoming nucleophile.