QL (chemical)

Isopropyl aminoethylmethyl phosphonite (NATO designation QL), also known as O-(2-diisopropylaminoethyl) O'-ethyl methylphosphonite, is a precursor chemical to the nerve agent VX.

Uses in chemical warfare
QL is a component in binary chemical weapons, mainly VX nerve agent. It, along with Methylphosphonyl difluoride (DF), was developed during the 1980s in order to replace an aging stockpile of unitary chemical weapons. QL is listed as a "Schedule One" chemical by the Chemical Weapons Convention.

Toxicity
QL itself is relatively non-toxic chemical. However, when reacted with sulfur, the corresponding sulphide of QL isomerizes into the highly toxic VX molecule.