Evaluation of the degradation efficiency and possible mechanism of various chemical decontaminants on series of vesicant sulfur mustards

Decontamination is one of the most effective ways to reduce the hazards of different sulfur mustards. Herein, reactions of various sulfur mustards with four classic decontaminant agents were investigated and their products identified by UPLC-MS/HRMS and GC-MS. Quantitative determinations of individual products in the reaction mixture allows to evaluate the kinetic parameters of the mustard reactions. The degradation rate of 1,2-bis(2-chloroethylthio) ethane and bis(2-chloroethylthioethyl) ether is obviously faster than that of sulfur mustard (SM), but the degradation rate of bis(2-chloroethylthio) methane and bis(2-chloroethylthiomethyl) ether is slower than that of SM. Degradation occurred in a nucleophilic substitution reaction between 2,3-butanedione monoximate, sodium phenolate, and with susceptible sites in the mustards. DS2 mainly exerts its degradation function by elimination reactions. However, 2,3-monoximate degrades sulfur mustards through nucleophilic substitution and elimination reaction. Based on the results of quantumchemical calculations, we assume that the difference of the decontamination rate may be related to the electrostatic potential energy of mustards itself.