Characterisation of a munition grade lewisite mixture

The three compounds trans-lewisite I, all-trans-lewisite II and all-trans-lewisite III have been identified in a munition grade lewisite mixture probably originating from World War II. all-trans-Lewisite II and all-trans-lewisite III were the main constituents in the mixture. NMR was used to confirm the identifications made by GC-MS and to identify the correct stereoisomers (all-trans). The ESI-MS spectra turned out to be difficult to interpret. The two major compounds were tentatively identified as lewisite III oxide and lewisite II dioxidised dimer. The 3,4-dimercaptotoluene (DMT) derivative of lewisite I or of 2-chlorovinylarsonous acid/lewisite oxide was identified by GC-MS. 2-chlorovinylarsonous acid (in equilibrium with lewisite oxide) and lewisite I give identical DMT-derivatives. The NMR result shows that this derivative originated from lewisite I and not from the acid/oxide.