Chemical and sensory properties of thiolactones

Model experiments were performed to determine the recoveries of γ-/δ-thiolactones by isolation from aqueous solutions and the stabilities of these volatiles upon heat treatment at different pH-values. Using simultaneous distillation-extraction, thiolactones exhibited higher recoveries than the corresponding lactones. Upon refluxing at neutral or alkaline conditions and subsequent liquid-liquid extraction, thiolactones turned out to be unstable. Using octakis-(2,3-di-O-acetyl-6-O-tert-butyldimethylsilyl)-γ-cyclodextrin as stationary phase for capillary gas chromatography, a baseline separation for γ-as well as δ-thiolactones could be achieved. Enantioselective enzyme-catalyzed hydrolysis of δ-thiooctalactone using Porcine Pancreas lipase proceeded enantioselectively, resulting in (R)-δ-thiooctalactone and (S)-5-mercaptooctanoic acid of high optical purity. GC-olfactomerry was applied to describe odor properties of thiolactone enantiomers and derivatives thereof.