Methylphosphonyl difluoride (DF), also called methyl difluorophosphite, methylphosphonic difluoride, and difluoromethylphosphine oxide, is a chemical weapon precursor. It is a Schedule 1 substance in the sense of the Chemical Weapons Convention

Chemical Weapons Convention

The Chemical Weapons Convention is an arms control agreement which outlaws the production, stockpiling and use of chemical weapons. Its full name is the Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on their Destruction...

. It is used for production of sarin

Sarin

Sarin, or GB, is an organophosphorus compound with the formula [2CHO]CH3PF. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687...

 and soman

Soman

Soman, or GD , is an extremely toxic chemical substance. It is a nerve agent, interfering with normal functioning of the mammalian nervous system by inhibiting the cholinesterase enzyme. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations according to UN...

.
Its chemical formula is CH₃POF₂.

Methylphosphonyl difluoride can be used as a component of binary chemical weapon

Binary chemical weapon

Binary chemical weapons or munitions are chemical weapons wherein the toxic agent is not contained within the weapon in its active state, but in the form of two chemical precursors, physically separated within the weapon...

s; an example is the M687

M687

The M687 is an American 155 mm binary sarin chemical weapon artillery shell. The design was standardized in 1976 and production began on December 16, 1987 at Pine Bluff Arsenal, Pine Bluff, Arkansas...

 artillery

Artillery

Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 shell, where it is used together with a mixture of isopropyl alcohol

Isopropyl alcohol

Isopropyl alcohol is a common name for a chemical compound with the molecular formula C3H8O. It is a colorless, flammable chemical compound with a strong odor...

 and isopropyl amine, producing sarin

Sarin

Sarin, or GB, is an organophosphorus compound with the formula [2CHO]CH3PF. It is a colorless, odorless liquid, which is used as a chemical weapon. It has been classified as a weapon of mass destruction in UN Resolution 687...

.