A continuous flow generator of organic hypochlorites for the neutralization of chemical warfare agent simulants

Abstract

Herein, we report the development of a continuous flow generator that produces highly reactive organic hypochlorites for the chemical neutralization of sulfur-based chemical warfare agent (CWA) simulants. The generator relies on resource and equipment with low environmental footprint and uses chemicals that are widely available and cheap. The standard decontamination protocol for sulfur-based CWA “mustard gas” (a.k.a. Yperite or HD) relies on bleach (aqueous sodium hypochlorite) as a convenient oxidative neutralization measure; however, the high lipophilicity of HD causes the formation of micelles and hence superficial and/or unselective detoxification. Aqueous bleach can be rapidly upgraded to more lipophilic organic hypochlorites (MeOCl, EtOCl, iPrOCl and tBuOCl). We demonstrate that the latter readily oxidize simulants of HD (such as chloroethyl ethyl sulfide (CEES)) to the corresponding sulfoxide (CEESO). With a fine tuning of the reaction conditions, the oxidation is nearly instantaneous and prevents the formation of toxic overoxidized sulfones, though organic hypochlorites also contribute to the innocuous chlorination of the neutralized sulfoxide. The assets of continuous flow technology enable the merging of both the upstream hypochlorite generator and the downstream neutralization setup to provide a safe, compact and mobile framework. Some aspects of the reactivity of organic hypochlorites with model sulfur compounds are also discussed by means of computational chemistry (DFT). The flexibility (simple chemicals, liquid feeds and wastes) and efficiency (space time yield = 3.74 kg L⁻¹ h⁻¹) of this protocol outclass other recently reported neutralization procedures in flow.