In
organic chemistry, a
thiol is a compound that contains the functional group composed of a
sulfur atom and a
hydrogen atom (-SH). Being the sulfur analogue of an
alcohol group (-OH), this functional group is referred to either as a
thiol group or a
sulfhydryl group. More traditionally, thiols are often referred to as
mercaptans.
When a thiol group is a substituent on an alkane, there are several ways of naming the resulting thiol
The term mercaptan comes from the Latin mercurium captans, meaning 'laying hold of mercury,' because the –SH group binds tightly to the element mercury.
Many thiols are colorless liquids having an odor resembling that of garlic. The odor of thiols is often strong and repulsive, particularly for those of low molecular weight. (A close selenium analog, butyl seleno-mercaptan, is responsible for the intolerable, persistent odor produced by the spraying of skunks.) Thiols bind strongly to skin proteins. Natural gas distributors began adding various forms of pungent thiols, usually ethanethiol, to natural gas, which is naturally odorless, after the deadly 1937 New London School explosion in New London, Texas. Thiols are also responsible for a class of wine faults caused by an unintended reaction between sulfur and yeast and the "skunky" odor of beer which has been exposed to ultraviolet light. However, not all thiols have unpleasant odors. For example, grapefruit mercaptan, a monoterpenoid thiol, is responsible for the characteristic scent of grapefruit.
