73207-98-4Relevant articles and documents
Influence of cyclic and acyclic cucurbiturils on the degradation pathways of the chemical warfare agent VX
Andrae, Beatrice,Bauer, Daniel,Ga?, Patrick,Koller, Marianne,Kubik, Stefan,Worek, Franz
supporting information, p. 5218 - 5227 (2020/07/23)
The highly toxic nerve agent VX is a methylphosphonothioate that degrades via three pathways in aqueous solution, namely through the hydrolysis of the P-O or P-S bonds, or the cleavage of the C-S bond at the 2-aminoethyl residue. In the latter case, an aziridinium ion and a phosphonothioate is formed. Here it is shown that acyclic or cyclic cucurbiturils inhibit these reactions in phosphate buffer at physiological pH and thus stabilise the nerve agent. When using unbuffered basic solutions as the reaction medium, however, in which the P-S or P-O bonds are normally hydrolysed preferentially, cucurbiturils turned out to strongly shift VX degradation towards the cleavage of the C-S bond. Cucurbit[7]uril, in particular, has a so pronounced effect under suitable conditions that it almost completely suppresses the formation of products resulting from the other degradation pathways. Investigations involving VX analogues in combination with computational methods suggest that one reason for the reaction control exerted by the cucurbiturils is the preorganisation of VX for aziridinium ion formation. In addition, cucurbit[7]uril also lowers the transition state of the reaction by stabilising the positive charge developing on the way to the product. Cucurbiturils thus have a marked effect on the reactivity of a highly toxic nerve agent, which potentially allows using them for decontamination purposes. This journal is
Investigating the breakdown of the nerve agent simulant methyl paraoxon and chemical warfare agents GB and VX using nitrogen containing bases
Wilson, Craig,Cooper, Nicholas J.,Briggs, Michael E.,Cooper, Andrew I.,Adams, Dave J.
supporting information, p. 9285 - 9291 (2019/01/03)
A range of nitrogen containing bases was tested for the hydrolysis of a nerve agent simulant, methyl paraoxon (MP), and the chemical warfare agents, GB and VX. The product distribution was found to be highly dependant on the basicity of the base and the quantity of water used for the hydrolysis. This study is important in the design of decontamination technology, which often involve mimics of CWAs.
Pathways for the Reactions Between Neurotoxic Organophosphorus Compounds and Oximes or Hydroxamic Acids
Bierwisch, Anne,Koller, Marianne,Worek, Franz,Kubik, Stefan
supporting information, p. 5831 - 5838 (2016/12/18)
To obtain mechanistic insight into the recently demonstrated detoxification ability of β-cyclodextrin derivatives containing substituents with oxime or hydroxamic acid residues, analogous glucose derivatives with the same substituents were treated with cyclosarin (GF), tabun (GA), and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) in (Tris)-HCl buffer (0.1 m, pH 7.40), and the different reaction pathways were studied by31P NMR spectroscopy and mass spectrometry. Consistent with previous reports, the oxime is phosphonylated by GF, which is followed by elimination of O-cyclohexyl methylphosphonate to afford a nitrile. Reaction of the hydroxamic acid with GA depends on whether the nitrogen atom of the hydroxamic acid bears a substituent or not. The unsubstituted hydroxamic acid affords a stable phosphate ester lacking the cyanide and the dimethylamino group of GA. If the hydroxamic acid is methylated, the initially formed phosphorylated product undergoes a number of transformations, including cleavage of the C–N bond of the hydroxamic acid. Reaction of the hydroxamic acid with VX involves a Lossen rearrangement. These investigations thus show that all investigated nucleophiles are irreversibly modified upon reaction with nerve agents under the chosen conditions, which indicates that cyclodextrins with oximes or hydroxamic acid as substituents are unlikely to afford catalytic nerve-agent scavengers.
Effective, Facile, and Selective Hydrolysis of the Chemical Warfare Agent VX Using Zr6-Based Metal-Organic Frameworks
Moon, Su-Young,Wagner, George W.,Mondloch, Joseph E.,Peterson, Gregory W.,DeCoste, Jared B.,Hupp, Joseph T.,Farha, Omar K.
supporting information, p. 10829 - 10833 (2015/11/27)
The nerve agent VX is among the most toxic chemicals known to mankind, and robust solutions are needed to rapidly and selectively deactivate it. Herein, we demonstrate that three Zr6-based metal-organic frameworks (MOFs), namely, UiO-67, UiO-67-NH2, and UiO-67-N(Me)2, are selective and highly active catalysts for the hydrolysis of VX. Utilizing UiO-67, UiO-67-NH2, and UiO-67-N(Me)2 in a pH 10 buffered solution of N-ethylmorpholine, selective hydrolysis of the P-S bond in VX was observed. In addition, UiO-67-N(Me)2 was found to catalyze VX hydrolysis with an initial half-life of 1.8 min. This half-life is nearly 3 orders of magnitude shorter than that of the only other MOF tested to date for hydrolysis of VX and rivals the activity of the best nonenzymatic materials. Hydrolysis utilizing Zr-based MOFs is also selective and facile in the absence of pH 10 buffer (just water) and for the destruction of the toxic byproduct EA-2192.
Role of the P-F bond in fluoride-promoted aqueous VX hydrolysis: An experimental and theoretical study
Marciano, Daniele,Columbus, Ishay,Elias, Shlomi,Goldvaser, Michael,Shoshanim, Ofir,Ashkenazi, Nissan,Zafrani, Yossi
supporting information, p. 10042 - 10049 (2013/01/15)
Following our ongoing studies on the reactivity of the fluoride ion toward organophosphorus compounds, we established that the extremely toxic and environmentally persistent chemical warfare agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is exclusively and rapidly degraded to the nontoxic product EMPA (ethyl methylphosphonic acid) even in dilute aqueous solutions of fluoride. The unique role of the P-F bond formation in the reaction mechanism was explored using both experimental and computational mechanistic studies. In most cases, the "G-analogue" (O-ethyl methylphosphonofluoridate, Et-G) was observed as an intermediate. Noteworthy and of practical importance is the fact that the toxic side product desethyl-VX, which is formed in substantial quantities during the slow degradation of VX in unbuffered water, is completely avoided in the presence of fluoride. A computational study on a VX-model, O,S-diethyl methylphosphonothioate (1), clarifies the distinctive tendency of aqueous fluoride ions to react with such organophosphorus compounds. The facility of the degradation process even in dilute fluoride solutions is due to the increased reactivity of fluoride, which is caused by the significant low activation barrier for the P-F bond formation. In addition, the unique nucleophilicity of fluoride versus hydroxide toward VX, in contrast to their relative basicity, is discussed. Although the reaction outcomes were similar, much slower reaction rates were observed experimentally for the VX-model (1) in comparison to VX.
A study of the kinetics of La3+-promoted methanolysis of S-aryl methylphosphonothioates: Possible methodology for decontamination of EA 2192, the toxic byproduct of VX hydrolysis
Dhar, Basab B.,Edwards, David R.,Brown, R. Stan
scheme or table, p. 3071 - 3077 (2011/05/09)
The kinetics of the La3+-catalyzed methanolysis of a series of S-aryl methylphosphonothioates (4a-e, phenyl substituents = 3,5-dichloro, 4-chloro, 4-fluoro, 4-H, 4-methoxy) were studied at 25 °C with ss pH control. The reaction involves saturation binding of the anionic substrates to dimeric La3+/methoxide catalysts formulated as La2 3+(-OCH3)x, where x = 2-5 depending on the solution ss pH. Cleavage of the La3+-bound methylphosphonothioates is fast, ranging from 5 × 10-3 s -1 to 5.5 × 10-5 s-1 for substrates 4a-e at a ss pH of 8.4 and 1.6 × 10-1 s-1 to 4 × 10-3s-1 at a ss pH of 11.7. The rate accelerations for the methanolysis of substrates 4a-e, relative to their background methoxide-promoted reactions, average 7 × 1010 and 1.5 × 109, respectively, at sspH's of 8.4 and 11.7. The catalytic system is predicted to cleave EA 2192 (S-2(N,N-di-iso-propylaminoethyl) methylphosphonothioate), a toxic byproduct of the hydrolysis of VX, with a t1/2 between 4 and 8 min at a ss pH of 8.4, and 27 min at a ss pH of 11.7.
Catalytic degradation of the nerve agent vx by water-swelled polystyrene-supported ammonium fluorides
Marciano, Daniele,Goldvaser, Michael,Columbus, Ishay,Zafrani, Yossi
scheme or table, p. 8549 - 8553 (2011/12/04)
The catalytic degradation of the nerve agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) by water-swelled polymer-supported ammonium fluorides is described. VX (0.06-0.53 mol/mol F -) is rapidly degraded (t1/2 ～ 10-30 min) to form the G-analogue (O-ethyl methylphosphonofluoridate), which hydrolyzes (t 1/2 ～ 1-1.5 h) to the nontoxic EMPA (ethyl methylphosphonic acid). The toxic desethyl-VX is not formed. The catalytic effect of fluoride is maintained even when 6 equiv of VX are loaded. GB (O-isopropyl methylphosphonofluoridate) and desethyl-VX agents are also degraded under these conditions.
Facile hydrolysis-based chemical destruction of the warfare agents VX, GB, and HD by alumina-supported fluoride reagents
Gershonov,Columbus,Zafrani
supporting information; experimental part, p. 329 - 338 (2009/04/10)
(Chemical Equation Presented) 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/Al2O3, AgF/KF/Al2O3, and KF/Al2O3 enriched by so-called coordinatively unsaturated fluoride ions (termed by us as ECUF-KF/Al2O3). When adsorbed on these sorbents, the nerve agent VX quickly hydrolyzed (t1/2 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 (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/Al2O 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 (t1/2 31P, 13C, and 19F MAS NMR.
