Methylphosphonic difluoride

The components of GB2 are methylphosphonic difluoride (DF) and a mixture of isopropyl alcohol and isopropyl amine (OPA). 

Binary component Does not apply Methylphosphonic difluoride [676-99-3]... 

This material is a general precursor for nerve agents. It may appear as a mixture with Methylphosphonic difluoride (C01-C047), known as Didi, that is used as a constituent for binary G-series nerve agents. 

GB manufactured in the USA was at least 93% pure. Impurities may include diisopropyl methylphosphonate (DIMP), a stable byproduct of manufacture, and methylphosphonic difluoride. DIMP is usually present at 2-3% in isopropyl methylphosphonate waste and is present in sampling wells, both on and off the RMA (Rosenblatt et al., 1995 Aulerich et al, 1979). In 1974, DIMP concentrations of 0.5 pg/1 (the limit of detection) to 44000 pg/1 were found in the groundwater near the Arsenal (Robson, 1981). 

Reactions of Phosphonlc and Phosphinic Acids and their Derivatives.-The reactions which take place between methylphosphonic difluoride and tetraalkoxysilanes lead to partial or complete... 

So-called "binary" weapons have been developed. The idea behind these is that two relatively non-toxic chemicals are placed in separate compartments in a shell. On firing these mix — perhaps by rupture of a bursting disk — and then are further mixed by the rotation of the shell in flight, so that the actual nerve agent is formed after the shell has been fired. For example, with Sarin (see above) methylphosphonic difluoride (CHgPOF ) and a mixture of isopropyl alcohol and isopropylamine (this catalyses the reaction) could be the two components. However, methylphosphonic difluoride is far from being non-toxic and the main advantage, in fact, seems to be that the separate components are easier to store and transport than Sarin itself. 

With the correspondingly more reactive methylphosphonic dichloride a mixture was obtained which contained traces of phosphinic acids. More important was the observation that methylphosphonic difluoride condensed smoothly with alkyl Grignard reagents to provide unsynametrical phosphinyl halides which precipitated as insoluble complexes of magnesium salts. Decomposition of the complexes with base gave the corresponding phosphinic acids, the yields of which increased as R increased... 

Methylphosphonic dichloride (10) and methylphosphonic difluoride (11) are the most important precursors of methylphosphonofluoridates 11 is invariably synthesized from 10. 

The chemistry illustrated in equation 17 was developed to meet the requirements of the binary weapons system. In the absence of base, the reaction of an alcohol with methylphosphonic difluoride (11) is slow and requires heating to drive to completion. In the presence of an amine, the reaction is extremely rapid and exothermic and proceeds in good yield. For the (US) binary munitions system for sarin, a mixture of propan-2-ol and isopropylamine are brought together with methylphosphonic difluoride when the separate canisters containing the reactants are ruptured as a result of the shock caused by firing the munition. The chemical reaction occurs within the time of flight of the munition ". ... 

The reaction of methylphosphonic difluoride (11) with a tetraalkoxysilane (alkyl= Me, Et, Pr ) at room temperature (equation 19) gave the corresponding G-agent in good yield (>80%) and high purity (>97%) by simple vacuum distillation of the crude reaction mixture ... 

Recommendation 3-2. Ideally, the binary precursors methylphosphonic difluoride (DF) and ethyl-2-diisopropyl-aminoethyl methylphosphonite (QL) stored at Pine Bluff Arsenal should be destroyed directly, either by burning in the Pine Bluff Chemical Destruction Facility incinerator or by plasma treatment. If these facilities cannot handle the fluorine-rich DF destruction products, the committee recommends that on-site neutralization followed by oxidative posttreatment of the neutralents be developed. The easiest posttreatment may be shipment to a commercial incinerator capable of dealing with high levels of fluorine. 

Binary GB2—methylphosphonic difluoride CH3F2PO (DF) plus isopropyl alcohol with an amine added (OPA)... 

A 1 4 mixture of tetraethoxysilane and methylphosphonic difluoride stirred at room temp, (the temp, rising to 33° over the first 50 min and to 70° over the following 5-6 min) - ethyl methylphosphonofluoridate. Y 81%. CAUTION the products are highly toxic acetylcholineesterase inhibitors. F.e.s. A.J. Muller, J. Org. Chem. 53, 3364-5 (1988). 

Thiodiglycol Phosphorus trichloride Sodium cyanide Methylphosphonic dIfluoride Phosphorus pentasulfide... 

However, binary production was not stopped entirely. On December 16, 1987, a 155-mm binary nerve artillery shell went into production. This munition held the precursors DF (difluor, short for methylphosphonic difluoride) and isopropyl alcohol, which by US law were required not only to be stored in different depots, but in different states. After firing, discs separating the precursors would rupture from the force of sudden acceleration (about 8 Gs), while the fast spin of the projectile (15,000 rpm) would yield a 70-percent mixture of sarin. 

Difluor is the abbreviation for methylphosphonic difluoride. Didi is a combination of methylphosphonic difluoride and methylphosphonic chloride used by Iraq for their quick mix process. 

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