Facile Hydrolysis-Based Chemical Destruction of the Warfare Agents VX, GB, and HD by Alumina-Supported Fluoride Reagents

Abstract

A facile solvent-free hydrolysis (chemical destruction) of the warfare agents VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate), GB (O-isopropyl methylphosphonofluoridate or sarin), and HD (2,2'-dichloroethyl sulfide or sulfur mustard) upon reaction with various solid-supported fluoride reagents is described. These solid reagents include different alumina-based powders such as KF/Al(2)O(3), AgF/KF/Al(2)O(3), and KF/Al(2)O(3) enriched by so-called coordinatively unsaturated fluoride ions (termed by us as ECUF-KF/Al(2)O(3)). When adsorbed on these sorbents, the nerve agent VX quickly hydrolyzed (t(1/2) range between 0.1-6.3 h) to the corresponding nontoxic phosphonic acid EMPA as a major product (>90%) and to the relatively toxic desethyl-VX (<10%). The latter byproduct was further hydrolyzed to the nontoxic MPA product (t(1/2) range between 2.2-161 h). The reaction rates and the product distribution were found to be strongly dependent on the nature of the fluoride ions in the KF/Al(2)O(3) matrix and on its water content. All variations of the alumina-supported fluoride reagents studied caused an immediate hydrolysis of the highly toxic GB (t(1/2) < 10 min) to form the corresponding nontoxic phosphonic acid IMPA. A preliminary study of the detoxification of HD on these catalyst supports showed the formation of the nontoxic 1,4-thioxane as a major product together with minor amounts of TDG and vinylic compounds within a few days. The mechanisms and the efficiency of these processes were successfully studied by solid-state (31)P, (13)C, and (19)F MAS NMR.

Component Mobility by a Minute Quantity of the Appropriate Solvent as a Principal Motif in the Acceleration of Solid-Supported Reactions

“…According to this suggestion, a fluoride ion reacts as a base to deprotonate water to afford a hydroxide ion that can attack the central phosphorus atom. 35 However, we did not exclude the possibility of an alternative mechanism by which the fluoride ion itself attacks the phosphorus atom to form a fluoridate intermediate, which immediately reacts with the basic surface of the alumina and water to furnish the final product EMP. According to both mechanisms, at the last stage of the hydrolysis, fluoride strongly binds to the alumina surface to form a strong Al−F bond.…”

“…34−38 Among other reactions examined, hydrolysis reactions of organophosphorus (OP) warfare agents, which hold relatively good leaving groups, with alumina-supported fluoride reagents were specifically investigated. 35,37 Typically, impregnation of potassium fluoride on the surface of neutral alumina leads to the formation of a heterogeneous support, which is effective in a variety of substitution, elimination, addition, and condensation reactions. 44−52 However, from our studies, we concluded that standard KF/Al 2 O 3 supports do not contain "available" (not connected to the surface) fluoride ions that are required for effective hydrolysis but rather hold hydroxide ions.…”

Infrared signature of micro-hydration in the organophosphate Sarin: an ab initio study

“…Examples of the influence of OP hydration include the observation of Henry's law deviations for the vapor pressure of Sarin (GB) over water [1], the acceleration of Sarin hydrolysis in humid environments, the pH and water quality dependence of Sarin hydrolysis [2], the moderate enhancement of Sarin photo-degradation with increasing relative humidity (RH) levels [3], and the reduction of volatility for the CWA simulant dimethyl methylphosphonate (DMMP) with increasing relative humidity (RH) [4]. Water is also known to directly impact the breakthrough, degradation and adsorption energies of OPs on a variety of different surfaces [5][6][7][8][9][10][11][12][13].…”

A HTS Assay for the Detection of Organophosphorus Nerve Agent Scavengers

“…[4b] As far as inorganic salts are concerned, solvent-free hydrolysis-based chemical destruction of various warfare agents has been described using alumina-supported fluoride reagents [14] or nanosize inorganic oxide particles. [15] Among the enzyme-mediated bioremediation methods recently reported, most promising are the exogenous administration of acetyl cholinesterase or human butyryl cholinesterase used as a stoichiometric trap.…”