Hydrolysis of Sesquimustards

The hydrolysis of the sesquimustards 1,2-bis(2-chloroethylthio)ethane (QN2) and 1,3-bis(2-chloroethylthio) propane (QN3) has been studied by 1H and 13C nuclear magnetic resonance spectroscopy. For both sesquimustards, stable cyclic sulfonium ions were observed in hydrolysis experiments in a 1 : 1 mixture of [D6]acetone and D2O. The cyclic sulfonium ions, which persist in the aqueous solution for up to a week, are likely to retain some toxicity and could possibly be used as markers for sesquimustards in the analysis of mustard-contaminated soil for chemical weapons treaty verification. The formation of a macrocyclic oxadithiaether was also demonstrated for QN2 but not QN3.