Tert-Butyl mercaptan (2-methyl-2-propanethiol, CAS # 75-66-1) is a highly odorous material, with an odor threshold of < 1ppb. It is a component in several Scentinel® Gas Odorants for use in odorizing natural gas so that leaks can be detected by smell before explosive levels are reached. It is also used as a chemical intermediate for synthesis of agrichemicals and other chemical substances.