ANALYTICAL AND SENSORY CHARACTERIZATION OF GAMMA-THIOLACTONES AND DELTA-THIOLACTONES

gamma-Thiolactones [5-alkyldihydro-2(3H)-thiaphenones] and delta-thiol actones (6-alkyltetrahydro-2H-thiopyran-2-ones) were synthesized via i sothiouronium salts by reaction of the corresponding oxygen-containing lactones with thiourea and hydrobromic acid. The identity of the comp ounds was confirmed by means of IR, MS, and H-1 and C-13 NMR. Separati on of the enantiomers of the thiolactones was achieved by capillary GC using akis(2,3-di-O-methyl-6-O-TBDMS)-beta-cyclo-dextrin as stationar y phase. The substitution of oxygen by sulfur induces tropical fruit n otes, which are more pronounced for the beta-thiolactones. Odor thresh olds are dependent on ring size and chain length.