Methylphosphonyl difluoride

Methylphosphonyl difluoride (DF), also known as EA-1251^[2] or difluoro,^[3] is a chemical weapon precursor. Its chemical formula is CH₃POF₂. It is a Schedule 1 substance under the Chemical Weapons Convention. It is used for production of sarin and soman as a component of binary chemical weapons; an example is the M687 artillery shell, where it is used together with a mixture of isopropyl alcohol and isopropyl amine, producing sarin.

Methylphosphonyl difluoride

Names
Preferred IUPAC name Methylphosphonic difluoride
Other names Methylphosphonyl difluoride Methylphosphonoyl difluoride, EA-1251
Identifiers
CAS Number	676-99-3 Y
3D model (JSmol)	Interactive image
Beilstein Reference	4-04-00-03508
ChemSpider	62813
MeSH	difluoride Methylphosphonic difluoride
PubChem CID	69610
UNII	Z7V517240K Y
CompTox Dashboard (EPA)	DTXSID5060980
InChI InChI=1S/CH3F2OP/c1-5(2,3)4/h1H3 Key: PQIOSYKVBBWRRI-UHFFFAOYSA-N
SMILES CP(F)(F)=O
Properties
Chemical formula	CH3POF2
Molar mass	100.00
Appearance	Colorless liquid
Odor	Pungent, acid-like[1]
Density	1.359 g/mL (77°F)[1]
Melting point	−37 °C; −35 °F; 236 K
Boiling point	100 °C; 212 °F; 373 K
Solubility in water	Decomposes[1]
Vapor pressure	36 mmHg (77°F)[1]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive, toxic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Methylphosphonyl difluoride can be prepared by reacting methylphosphonyl dichloride with hydrogen fluoride (HF) or sodium fluoride (NaF).

Safety

Methylphosphonyl difluoride is both reactive and corrosive. It is absorbed through skin and causes burns and mild nerve agent symptoms. It reacts with water, producing HF fumes and methylphosphonic acid as a result. It is also capable of corroding glass.

Significance in international relations

In 2013–2014, the stockpile of chemicals covered by the CWC was removed from Syria and destroyed. Of the stockpile, 581 tons (over 96%) of the stockpile was DF. It was destroyed by the U.S. Army on the MV Cape Ray by hydrolysis.^[4][5]