The room-temperature reactions of the chemical warfare agents VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate), GD (3,3-dimethyl-2-butyl methylphosphonofluoridate, or Soman), and HD (2,2′-dichloroethyl sulfide, or mustard) with nanosize MgO have been studied using solid-state MAS NMR. All three agents hydrolyze on the surface of the very reactive MgO nanoparticles. VX yields ethyl methylphosphonic acid (EMPA) and methylphosphonic acid (MPA), but no toxic S-(2-diisopropylamino)ethyl methylphosphonothioate (EA-2192). GD forms both GD-acid and MPA. For HD, in addition to hydrolysis to thiodiglycol, about 50% elimination to divinyl sulfide occurs. The reaction kinetics for all three agents are characterized by a fast initial reaction followed by gradual slowing to a steady-state reaction with first-order behavior. The fast reaction is consistent with liquid spreading through the porous nanoparticle aggregates. The steady-state reaction is identified as a gas-phase reaction, mediated by evaporation, once the liquid achieves its volume in the smallest available pores.
The room-temperature reactions of the chemical warfare agents VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate), HD (2,2‘-dichloroethyl sulfide, or mustard), and their common simulants,
O,S-diethyl phenylphosphonothioate (DEPPT) and 2-chloroethyl phenyl sulfide (CEPS), with NaY and
silver-exchanged (AgY) zeolites have been studied using solid-state magic angle spinning NMR. VX
hydrolyzes via exclusive cleavage of the P−S bond on both NaY and AgY to yield ethyl methylphosphonate
(EMPA). The reaction is significantly faster on AgY than on NaY, suggesting catalysis by silver. On AgY,
an intermediate silver salt of EMPA is apparently formed which is slowly converted to ethyl 2-(diisopropylamino)ethyl methylphosphonate (QB, the desulfurized analogue of VX) in about a 78% yield. DEPPT
similarly hydrolyzes via P−S cleavage on AgY to yield an apparent silver salt of ethyl phenylphosphonate,
which does not undergo further reaction to the desulfurized analogue. No reaction is observed for DEPPT
on NaY. HD on AgY forms both vinyl sulfide and the cyclic ether 1,4-thioxane. HD reacts faster on NaY
to exclusively form the CH-TG sulfonium ion (HOCH2CH2SCH2CH2S+[CH2CH2OH]2). CEPS also reacts
faster on NaY, forming 2-hydroxyethyl phenyl sulfide. On AgY, CEPS does not give the vinyl product, but
does yield the ether product PhSCH2CH2OCH2CH2SPh. A mechanism is proposed for the silver-catalyzed
hydrolysis of VX, the desulfurization of the cleaved thiol, and the formation of QB.
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