Grapefruit mercaptan

Grapefruit mercaptan is the common name for a natural organic compound found in grapefruit. It is a monoterpenoid that contains a thiol (or mercaptan) functional group. Volatile thiols typically have very strong, often unpleasant odors which can be detected by humans in very low concentrations. Grapefruit mercaptan has a very potent, but not unpleasant, odor and it is the chemical constituent primarily responsible for the aroma of grapefruit. This characteristic aroma is a property of only the R-stereoisomer.

Pure grapefruit mercaptan, or citrus-derived oils rich in grapefruit mercaptan, are sometimes used in perfumery and the flavor industry to impart citrus aromas and flavors. However, both industries actively seek substitutes for grapefruit mercaptans for use as a grapefruit flavorant, since its decomposition products are often highly disagreeable to the human sense of smell.