Tabun

Tabun, given the NATO designation GA, is an extremely toxic nerve agent of the organophosphate family and does not occur in nature. At room temperature the pure compound is a clear, viscous liquid, though manufacturing impurities usually leave it yellow or brown, and it slowly evaporates into the air with a faint fruity or almond-like odor. It was discovered by the German researcher Gerhard Schrader in late December 1936 while he was developing organophosphate insecticides for IG Farben, and it works by potently inhibiting acetylcholinesterase, an enzyme essential to the nervous system.