Pinacolyl methylphosphonate Soman

In addition, due to the reversibility of the binding reaction of sarin and soman to CarbE, it appears that CarbEs are involved in metabolic detoxification of these agents to their corresponding nontoxic metabolites isopropyl methylphosphonic acid (IMPA) and pinacolyl methylphosphonic acid (PMPA) (Jokanovic et al, 1996). 

FIGURE 19.2 Hydrolysis pathway of sarin (GB), soman (GD), and cyclosarin (GIO hydrolysis pathway of nerve agents proceeds through the alkyl methylphosphonic acids, isopropyl methylphosphonic acid (IMPA), pinacolyl methylphosphonic acid (PMPA), and cyclohexyl methylphosphonic acid (CMPA) to methylphos-ponic acid (MPA). Analysis of the alkyl methylphosphonic acids allows identification of the parent agent, while assay of MPA is nonspecific. 

Sarin is metabolized to isopropyl methylphosphonic acid (IMPA) and excreted by the kidneys (Little et al., 1986). Approximately 50% of soman is converted to free pinacolyl-methylphosphonic acid within 1 min in mice. The half-life of this metabolite is less than 1 h (Reynolds et al., 1985). 

FIGURE 52.1. Metabolic detoxification of warfare nerve agents tabun, sarin, soman, and VX in mammals in vivo. Chemical names of metabolites are EDMPA - ethyl dimethylaminophosphoric acid, IMPA - isopropyl methylphosphonic acid, PMPA - pinacolyl methyl-phosphonic acid, EMPA - ethyl methylphosphonic acid, and MPA - methylphosphonic acid. 

Nerve agent residues remaining in the natural environment are likely to undergo substantial hydrolysis in the period immediately following dissemination. In investigation of allegations of use it is therefore important to analyse for trace levels of hydrolysis products. The important hydrolysis products of sarin, soman and GF are the isopropyl, pinacolyl and cyclohexyl methylphosphonic acids, which are slowly hydrolysed further to methylphosphonic acid. VX is predominantly hydrolysed to ethyl methylphosphonic acid... 

The reaction of Sarin and Soman with sodium phenolate by runs the same way. The reaction of Soman with sodium phenolate is own in Figure 1. The peak with dution temperature 135 C is non-reacted Soman, the peak no.2 with dution temperature 182 °C is the product of solvolysis of Soman by ethanol, e.g. pinacolyl ethyl methylphosphonate. The peak no. 3 is non-reacted phaiol and the peak no.4 with elution temperature 240 C is appropriate phenyl pinacoljd methylphosphonate. 

FIGURE 59.1 Metabolic detoxification of tabun, soman, sarin, cyclosarin, and VX. Abbreviations EDMPA, ethyl dimethylaminophosphoric acid EPA, ethyl phosphoric acid EPCA, 0-ethyl-cyanophosphoric acid IMPA, isopropyl methylphosphonic acid PMPA, pinacolyl meth-ylphosphonic acid CHMPA, cyclohexyl methylphosphonic acid EMPA, ethyl methylphosphonic acid MPA, methylphosphonic acid DAET, 2-(diisopropylamino) ethanethiol DAEMS, 2-(diisopropylaminoethyl) methylsulphide TMT, thiol S-methyltransferase (EC 2.1.1.9) (Nakajima et al., 1998 Katagi et al., 1999 Jokanovic, 2001, 2009 Evans et al., 2008 Black, 2010 Tenberken et al., 2010 Reiter et al., 2011 Black and Read, 2013 Kranawetvogl et al., 2013). 

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