methanethiol

Methanethiol, also known as methyl mercaptan, is the simplest thiol (mercaptan) with the chemical formula CH3SH. It is a colorless gas or volatile liquid at room temperature and has a very strong, unpleasant odor often likened to rotten cabbage or garlic. Because thiols have extremely low odor thresholds, trace amounts are often detectable by smell long before any other signs of exposure.

Occurrence and production are diverse. Methanethiol is produced naturally during the anaerobic decomposition of organic matter and by certain microbes in the gut, landfills, sewers, and compost facilities. It is also released during the processing of sulfur-containing compounds. Industrially, it is produced on a larger scale by thioalkylation of methanol with hydrogen sulfide over catalysts. In some gas odorization practices, methanethiol or related mercaptans have historically been used to impart a detectable odor, though tert-butyl mercaptan is more commonly employed today.

Chemical properties and behavior are typical of thiols: methanethiol is a reactive, flammable compound that can be oxidized to disulfides and can form a thiolate anion under basic conditions. It participates in a range of chemical syntheses as a sulfur-containing intermediate and can react to give various thiol derivatives.

Safety and handling are important due to its toxicity and irritant properties. Methanethiol can cause respiratory irritation and is a lachrymator at sufficient concentrations. It should be handled in well-ventilated facilities with appropriate engineering controls and protective equipment, in accordance with applicable regulations governing hazardous substances.