Locus-specific microemulsion catalysts for sulfur mustard (HD) chemical warfare agent decontamination

Fallis, Ian Andrew ORCID: https://orcid.org/0000-0001-7361-0182, Griffiths, Peter Charles, Cosgrove, Terence, Dreiss, Cecile A., Govan, Norman, Heenan, Richard K., Holden, Ian, Jenkins, Robert Leyshon, Mitchell, Stephen J., Notman, Stuart, Platts, James Alexis ORCID: https://orcid.org/0000-0002-1008-6595, Riches, James and Tatchell, Thomas 2009. Locus-specific microemulsion catalysts for sulfur mustard (HD) chemical warfare agent decontamination. Journal of the American Chemical Society 131 (28) , pp. 9746-9755. 10.1021/ja901872y

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Abstract

The rates of catalytic oxidative decontamination of the chemical warfare agent (CWA) sulfur mustard (HD, bis(2-chlororethyl) sulfide) and a range (chloroethyl) sulfide simulants of variable lipophilicity have been examined using a hydrogen peroxide-based microemulsion system. SANS (small-angle neutron scattering), SAXS (small-angle X-ray scattering), PGSE-NMR (pulsed-gradient spin−echo NMR), fluorescence quenching, and electrospray mass spectroscopy (ESI-MS) were implemented to examine the distribution of HD, its simulants, and their oxidation/hydrolysis products in a model oil-in-water microemulsion. These measurements not only present a means of interpreting decontamination rates but also a rationale for the design of oxidation catalysts for these toxic materials. Here we show that by localizing manganese−Schiff base catalysts at the oil droplet−water interface or within the droplet core, a range of (chloroethyl) sulfides, including HD, spanning some 7 orders of octanol−water partition coefficient (Kow), may be oxidized with equal efficacy using dilute (5 wt. % of aqueous phase) hydrogen peroxide as a noncorrosive, environmentally benign oxidant (e.g., t1/2 (HD) 18 s, (2-chloroethyl phenyl sulfide, C6H5SCH2CH2Cl) 15 s, (thiodiglycol, S(CH2CH2OH)2) 19 s {20 °C}). Our observations demonstrate that by programming catalyst lipophilicity to colocalize catalyst and substrate, the inherent compartmentalization of the microemulsion can be exploited to achieve enhanced rates of reaction or to exert control over product selectivity. A combination of SANS, ESI-MS and fluorescence quenching measurements indicate that the enhanced catalytic activity is due to the locus of the catalyst and not a result of partial hydrolysis of the substrate.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Subjects:	Q Science > QD Chemistry
Publisher:	American Chemical Society
ISSN:	0002-7863
Last Modified:	17 Oct 2022 09:51
URI:	https://orca.cardiff.ac.uk/id/eprint/5935

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