1832-53-7Relevant academic research and scientific papers
Autocatalytic hydrolysis of V-type nerve agents
Yang, Yu-Chu,Szafraniec, Linda L.,Beaudry, William T.,Rohrbaugh, Dennis K.,Procell, Lawrence R.,Samuel, John B.
, p. 8407 - 8413 (1996)
Both V-type nerve agents MeP(O)(OR)(SCH2CH2NR′2), VX (R = C2H5; R′ = i-C3H7) and its isomeric analog RVX (the "Russian V-agent", R = i-C4H9; R′ = C2H5), react slowly but completely with an equimolar amount of H2O via exclusive P-S cleavage to produce the corresponding phosphonic acid (MeP(O)(OR)OH) and 2-aminoethanethiol (HSCH2CH2NR′2). The reaction is believed to be initiated by nucleophilic attack of the deprotonated phosphonic acid on the protonated V-agent to produce a diphosphonate intermediate ((MeP(O)(OR))2O) that rapidly hydrolyzes to regenerate the phosphonic acid. The autocatalytic ionic chain reaction is thus continued in the nearly nonaqueous reaction medium. The viscous final product mixture remains reactive toward freshly added trace amounts of the V-agent, giving the same final reaction half-life of 13-15 h at 23 °C. When water is insufficient and depleted, the diphosphonate intermediate accumulates and reacts with the aminoethanethiol to regenerate the V-agent. This autocatalytic hydrolysis process is not observed with a simpler phosphonothioate analog (MeP(O)(OC2H5)(SC2H5)), which suggests that the attack of the phosphonic acid on the V-agent is intramolecularly assisted by the protonated amino group.
Atmospheric chemistry of diethyl methylphosphonate, diethyl ethylphosphonate, and triethyl phosphate
Aschmann, Sara M.,Tuazon, Ernesto C.,Atkinson, Roger
, p. 2282 - 2291 (2005)
Rate constants for the reactions of OH radicals and NO3 radicals with diethyl methylphosphonate [DEMP, (C2H5O) 2P(O)CH3], diethyl ethylphosphonate [DEEP, (C 2H5O)2P(O)C2H5], and triethyl phosphate [TEP, (C2H5O)3PO] have been measured at 296 ± 2 K and atmospheric pressure of air using relative rate methods. The rate constants obtained for the OH radical reactions (in units of 10-11 cm3 molecule-1 s-1 were as follows: DEMP, 5.78 ± 0.24; DEEP, 6.45 ± 0.27; and TEP, 5.44 ± 0.20. The rate constants obtained for the NO3 radical reactions (in units of 10-16 cm3 molecule-1 s-1) were the following: DEMP, 3.7 ± 1.1; DEEP, 3.4 ± 1.4; and TEP, 2.4 ± 1.4. For the reactions of O3 with DEMP, DEEP, and TEP, an upper limit to the rate constant of -20 cm3 molecule-1 s-1 was determined for each compound. Products of the reactions of OH radicals with DEMP, DEEP, and TEP were investigated using in situ atmospheric pressure ionization mass spectrometry (API-MS) and, for the TEP reaction, gas chromatography with flame ionization detection (GC-FID) and in situ Fourier transform infrared (FT-IR) spectroscopy. The API-MS analyses show that the reactions are analogous, with formation of one major product from each reaction: C2H5OP(O)(OH)CH3 from DEMP, C 2H5OP(O)(OH)C2H2 from DEEP, and (C2H5O)2P(O)OH from TEP. The FT-IR and GC-FID analyses showed that the major products (and their molar yields) from the TEP reaction are (C2H5O)2P(O)OH (65-82%, initial), CO2 (80 ± 10%), and HCHO (55 ± 5%), together with lesser yields of CH3CHO (11 ± 2%), CO (11 ± 3%), CH3C(O)OONO2 (8%), organic nitrates (7%), and acetates (4%). The probable reaction mechanisms are discussed.
Catalytic degradation of the nerve agent vx by water-swelled polystyrene-supported ammonium fluorides
Marciano, Daniele,Goldvaser, Michael,Columbus, Ishay,Zafrani, Yossi
, p. 8549 - 8553 (2011)
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.
A Versatile Self-Detoxifying Material Based on Immobilized Polyoxoniobate for Decontamination of Chemical Warfare Agent Simulants
Dong, Jing,Lv, Hongjin,Sun, Xiangrong,Wang, Yin,Ni, Yuanman,Zou, Bo,Zhang, Nan,Yin, Anxiang,Chi, Yingnan,Hu, Changwen
, p. 19208 - 19215 (2018)
A decontaminating composite, Mg3Al-LDH-Nb6, has been successfully prepared by immobilizing Lindqvist [H3Nb6O19]5? (Nb6) into a Mg3Al-based layered double hydroxide (Mg3Al-LDH). To our knowledge, this represents the first successful approach to the immobilization of polyoxoniobate. As a versatile catalyst, Mg3Al-LDH-Nb6 can effectively catalyze the degradation of both vesicant and nerve agent simulants by multiple pathways under mild conditions. Specifically, the sulfur mustard simulant, 2-chloroethyl ethyl sulfide (CEES), is converted into the corresponding nontoxic 2-chloroethyl ethyl sulfoxide (CEESO) by selective oxidation, whereas the Tabun (G-type nerve agent) simulant, diethyl cyanophosphonate (DECP), and the VX (V-type nerve agent) simulant, O,S-diethyl methylphosphonothioate (OSDEMP), are detoxified through hydrolysis and perhydrolysis, respectively. A possible mechanism is proposed on the basis of control experiments and spectroscopic studies. The Mg3Al-LDH-Nb6 composite exhibits remarkable robustness and can be readily reused for up to ten cycles with negligible loss of its catalytic activity. More importantly, a protective “self-detoxifying” material has easily been constructed by integrating Mg3Al-LDH-Nb6 into textiles. In this way, the flexible and permeable properties of textiles have been combined with the catalytic activity of polyoxoniobate to remove 94 % of CEES in 1 h by using nearly stoichiometric dilute H2O2 (3 %) as oxidant with 96 % selectivity.
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.
, p. 10829 - 10833 (2015)
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.
Enzymatic neutralization of the chemical warfare agent VX: Evolution of phosphotriesterase for phosphorothiolate hydrolysis
Bigley, Andrew N.,Xu, Chengfu,Henderson, Terry J.,Harvey, Steven P.,Raushel, Frank M.
, p. 10426 - 10432 (2013)
The V-type nerve agents (VX and VR) are among the most toxic substances known. The high toxicity and environmental persistence of VX make the development of novel decontamination methods particularly important. The enzyme phosphotriesterase (PTE) is capable of hydrolyzing VX but with an enzymatic efficiency more than 5 orders of magnitude lower than with its best substrate, paraoxon. PTE has previously proven amenable to directed evolution for the improvement of catalytic activity against selected compounds through the manipulation of active-site residues. Here, a series of sequential two-site mutational libraries encompassing 12 active-site residues of PTE was created. The libraries were screened for catalytic activity against a new VX analogue, DEVX, which contains the same thiolate leaving group of VX coupled to a diethoxyphosphate core rather than the ethoxymethylphosphonate core of VX. The evolved catalytic activity with DEVX was enhanced 26-fold relative to wild-type PTE. Further improvements were facilitated by targeted error-prone PCR mutagenesis of loop-7, and additional PTE variants were identified with up to a 78-fold increase in the rate of DEVX hydrolysis. The best mutant hydrolyzed the racemic nerve agent VX with a value of kcat/Km = 7 × 104 M-1 s-1, a 230-fold improvement relative to wild-type PTE. The highest turnover number achieved by the mutants created for this investigation was 137 s-1, an enhancement of 152-fold relative to wild-type PTE. The stereoselectivity for the hydrolysis of the two enantiomers of VX was relatively low. These engineered mutants of PTE are the best catalysts ever reported for the hydrolysis of nerve agent VX.
Magnesium Exchanged Zirconium Metal-Organic Frameworks with Improved Detoxification Properties of Nerve Agents
Gil-San-Millan, Rodrigo,López-Maya, Elena,Platero-Prats, Ana E.,Torres-Pérez, Virginia,Delgado, Pedro,Augustyniak, Adam W.,Kim, Min Kun,Lee, Hae Wan,Ryu, Sam Gon,Navarro, Jorge A. R.
, p. 11801 - 11805 (2019)
UiO-66, MOF-808 and NU-1000 metal-organic frameworks exhibit a differentiated reactivity toward [Mg(OMe)2(MeOH)2]4 related to their pore accessibility. Microporous UiO-66 remains unchanged while mesoporous MOF-808 and hierarchical micro/mesoporous NU-1000 materials yield doped systems containing exposed MgZr5O2(OH)6 clusters in the mesoporous cavities. This modification is responsible for a remarkable enhancement of the catalytic activity toward the hydrolytic degradation of P-F and P-S bonds of toxic nerve agents, at room temperature, in unbuffered aqueous solutions.
Alkyl methylphosphonic acids, the degradation products of organophosphorous CWA - preparation and direct quantitative GC-FID analysis
Polec, Iwona,Kielczewska, Anna,Konopski, Leszek,Oleksa, Grazyna,Krukowska, Hanna Nowacka,Legocki, Jan
, p. 1251 - 1265 (2010)
Seven alkyl methylphosphonic acids, products of hydrolytic degradation of organophosphorus chemical warfare agents, were obtained with a high purity (mostly above 98%), with the aim of being applyed as future certified reference materials. Ethyl (EMPA), i
Degradation of Paraoxon and the Chemical Warfare Agents VX, Tabun, and Soman by the Metal-Organic Frameworks UiO-66-NH2, MOF-808, NU-1000, and PCN-777
De Koning, Martijn C.,Van Grol, Marco,Breijaert, Troy
, p. 11804 - 11809 (2017)
In recent years, Zr-based metal-organic frameworks (MOFs) have been developed that facilitate catalytic degradation of toxic organophosphate agents, such as chemical warfare agents (CWAs). Because of strict regulations, experiments using live agents are not possible for most laboratories and, as a result, simulants are used in the majority of cases. Reports that employ real CWAs are scarce and do not cover the whole spectrum of agents. We here present a comparative study in which UiO-66-NH2, NU-1000, MOF-808, and PCN-777 are evaluated for their effectiveness in the degradation of paraoxon and the chemical warfare agents tabun, VX, and soman, in N-ethylmorpholine buffer (pH 10) as well as in pure water. All MOFs showed excellent ability to degrade the agents under basic conditions. It was further disclosed that tabun is degraded by different mechanisms depending on the conditions. The presence of an amine, either as part of the MOF structure (UiO-66-NH2) or in the agent itself (VX, tabun), is the most important factor governing degradation rates in water. The results show that MOFs have great potential in future protective applications. Although the use of simulants provides valuable information for initial screening and selection of new MOFs, the use of live agents revealed additional mechanisms that should aid the future development of even better catalysts.
Analysis of chemical neutralization products of phosphonothiolates by gas chromatography mass spectrometry
Gupta,Palit,Dubey,Raza
, p. 1631 - 1637 (2003)
A series of phosphonothiolates, including the highly toxic O-Ethyl-S-(2-diisopropylamino) ethyl methylphosphonothioate (VX), have been subjected to chemical neutralization reaction with metallic sodium. The phosphonothiolates decompose to their respective phosphonic and phosphonothioic acids and this results in the detoxification of VX. GC/MS technique in both EI and CI mode has been applied for reaction monitoring and final identification of the neutralization products formed in this reaction.
