Locus-Specific Microemulsion Catalysts for Sulfur Mustard (HD) Chemical Warfare Agent Decontamination

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• 作者：Ian A. Fallis ; Peter C. Griffiths ; Terence Cosgrove ; Cecile A. Dreiss ; Norman Govan ; Richard K. Heenan ; Ian Holden ; Robert L. Jenkins ; Stephen J. Mitchell ; Stuart Notman ; Jamie A. Platts ; James Riches
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：July 22, 2009
• 年：2009
• 卷：131
• 期：28
• 页码：9746-9755
• 全文大小：295K
• 年卷期：v.131,no.28(July 22, 2009)
• ISSN：1520-5126

文摘

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 (K_ow), may be oxidized with equal efficacy using dilute (5 wt. % of aqueous phase) hydrogen peroxide as a noncorrosive, environmentally benign oxidant (e.g., t_1/2 (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.