REGIOSELECTIVE SYNTHESIS AND CHARACTERIZATION OF 6-O-ALKANOYLGLUCONOLACTONES

6-O-Alkanoylgluconolactones, a novel class of carbohydrate ester-linke d surfactants containing a lactone head group, have been synthesized e nzymatically from the unprotected aldonolactone. The synthesis was acc omplished by regioselective esterification of glucono-1,5-lactones at C-6 by porcine pancreatic lipase in the solvent pyridine. These compou nds were found to exhibit a sharp increase in solubility at 90-96 degr ees C but remained soluble well below their initial dissolution temper ature, precipitating at 30-37 degrees C. To determine the cause of thi s unusual solubility behavior, the composition of the precipitate was characterized by H-1 and C-13 NMR, and GC-MS. Analysis of the precipit ates identified the material as a hydrolysate containing alkanoylgluco no-1,5-lactone, alkanoylglucono-1,4-lactone and alkanoylgluconic acid. The hydrolysis and isomerization of the lactone gave a mixture of com pounds that are more soluble than the corresponding pure alkanoylgluco n-delta-lactone.