Cyclohexyl methylphosphonic acid

Hydrolysis products GF s hydrolysis products, hydrofluoric and cyclohexyl-methylphosphonic acids, are less toxic than their parent compound. 

Evans, R.A., Jakubowski, E.M., Muse, W.T., Matson, K., Hulet, S.W., Mioduszewski, R.J., Thomson, S.A., Totura, A.L., Retmer, J.A., Crouse, C.L. (2008). Quantification of sarin and cyclosarin metabolites isopropyl methylphosphonic acid and cyclohexyl methylphosphonic acid in minipig plasma using isotope-dilution and liquid chromatography-time-of-flight mass spectrometry. J. Anal. Toxicol. 32(1) 78-85. 

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. 

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... 

Fig. 1 HPLC-ESP MS reconstructed (total) ion chromatogram from a standard mixture of alkyl phosphonic acids at a concentration of 1 p-g/ml each 1) methylphosphonic acid (MPA) 2) ethylphosphonic acid (EPA) 3) methyl ethylphosphonic acid (MEPA) 4) ethyl methylphosphonic acid (EMPA) 5) ra-propylphosphonic acid (nPrPA) 6) ethyl ethylphosphonic acid (EEAP) 7) isopropyl methylphosphonic acid (iPrMPA) 8) n-propyl methylphosphonic acid (nPrMPA) 9) isopropyl ethylphosphonic acid (iPrEPA) 10) n-propyl ethylphosphonic acid (nPrEPA) 11) isohutyl methylphosphonic acid (iBuMPA) 12) cyclohexyl methylphosphonic acid (CHMPA) 13) pinacolyl methylphosphonic acid (PinMPA).

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). 

Clark II diphenylcyanoarsine, DC CMPA cyclohexyl methylphosphonic acid CTAB cetyltrimethylammoniumbromide CVAA chlorovinyl arsonous acid CVAO chlorovinyl arsonous oxide CWA Chemical Warfare Agent CWC Chemical Weapons Convention CWS Chemical Warfare Service CX phosgene oxime DA Diphenylcyanoarsine (Clark I)... 

Figure 1 shows the structures of the Schedule 1 alkylphosphonofluoridates and the Schedule 2 alkyl methylphosphonic acids and the hydrolysis reaction. The most common alkylphosphonic acids and the hydrolysis reaction. The most common alkyl groups and the ones examined in this study (ethyl, isopropyl, isobutyl, cyclohexyl) and pinacolyl) are shown at the bottom of Figure 1. 

The El mass spectra obtained for the TMS derivatives of five alkyl methylphosphonic acids, where alkyl = ethyl, isopropyl, isobutyl, cyclohexyl and pinacolyl, are shown in Figure 7. Note the ion at m/z 153 is the dominant ion (base peak) in all spectra. The ion at m/z 169 (10-50% of base peak) is also common to all 5 spectra. Both ions can be used for MS screening of this class of compounds. 

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