Pinacolyl methylphosphonic acid PMPA

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. 

GD (shaip doublets centered near 29 ppm. Figure 3) readily hydrolyzes (see Scheme 1) to pinacolyl methylphosphonic acid (PMPA, broad peak at 24 ppm) which binds to the oxide surface as shown in Scheme 1. Additionally, on -MgO and AP CaO a second, minor product peak appears near 20 ppm. Based on the results for high-loading GD on AP-AI2O3 (see below) diis second product is assigned to die corresponding metal pinacolyl mediy hosphonates rather than MPA since PMPA is extremely resistant to hydrolysis. 

FIGURE 22.4 Mass spectra of pinacolyl methylphosphonic acid (PMPA) on soil particles, at a concentration of 0.02 molecular layer. Top MS-1 bottom MS-2, following isolation and fragmentation of the conjugate base at m/z 179. 

The primary hydrolysis product of GD is pinacolyl methylphosphonic acid (PMPA). Other hydrolysis products include the breakdown of PMPA to MPA and pinacolyl alcohol. Major impurities found in GD consist of dipinacolyl methylphosphonate, methyl pinacolyl methylphosphonate, methyl methylphosphonofluoridate and methyl methacrylate. Toxicological data for MPA was discussed earlier in Section 2.2 and can be found in Table 2.4. There are no current toxicity data available on the major degradation product PMPA, although it is structurally similar to IMPA, which exhibits low toxicity (Tables 2.4 and 2.5). Toxicity reports have found that methyl methacrylate is considered to possess moderately acute effects and is irritating to the eyes... 

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. 

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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