Efficient resolution of 3-phenoxy-1,2-propanediol by immobilized lipase on amphiphilic comb polymer modified TiO₂

An amphiphilic microenvironment is a key element to the lipase which catalyzes substrates at the aqueous and hydrophobic interface. An amphiphilic comb copolymer, poly(sodium acrylate)-g-methoxy poly(ethylene oxide), was introduced for the post-functionalization of mesoporous TiO₂. The lipase from Burkholderia ambifaria YCJ01 was immobilized on the comb copolymer modified TiO₂. The activity of immobilized lipase YCJ01 showed that comb polymer which side chain with a molecular weight of 1000 was the best material for the functionalization of TiO₂. The amount of adsorbed lipase was 55.6 mg/g support and the immobilized lipase activity was 6076.1 U/g support. It was worth to note that the immobilized lipase achieved more than 200% of its origin activity in hydrophobic solvents and very stable in hydrophilic solvents. The immobilized lipase was used as a catalyst for resolution of 3-phenoxy-1,2-propanediol, and showed high enantioselectivity (ee_p ≥ 99%) in all tested organic solvents. This might be explained that comb polymer with amphiphilic, multiple side chains features could well stabilize the favorite active conformation of lipase to the resolution substrate in all tested organic solvents. In diisopropyl ether reaction solvent, the yield of 49.8% and an enantiomeric excess of 99.2% for S-diacetate were achieved after one operation, and maintained relative yield of 72% for S-diacetate even after six reaction cycles with no significant decrease in the enantiomeric excess of product.