Cleavage of Phenylphosphonothioates by Hydroxide Ion and by Micellar Iodosobenzoate

Abstract

0,s-Dialkyl phenylphosphonothioates (5a-d) are good simulants for the nerve agent VX in nucleophilic substitution reactions. Hydrolyses of 5a-d in 0.1 M aqueous NaOH occur with half-lives of 4-18 min and with the formation ofboth P-S and P-0 cleavage products, 6a-d and 7a-d, respectively. Reactions of these substrates with o-iodosobenzoate (IBA), however, are chemospecific at P-S. For example, in 0.05 M micellar cetyltrimethylammonium chloride (CTAC1) at pH 9.5 (pD 9.9) in DzO, 0.063 M IBA cleaved 0.02 M 5a (to 6a) with K = 0.115 min-l, t112 -6 min. The second-order rate constant for this reaction in 0.1 M CTACl solution was -1.9 M-l min-l.The destruction of phosphorus-based nerve agents under battlefield ("decontamination") or treaty-mandated stockpile ("demilitarization") conditions continues to be a matter of urgent ~o n c e r n .~-~~ For fluorophosphonate toxins such as soman (GD), 1, and sarin (GB), 2, mildly basic aqueous micellar solutions ofo-iodosobenzoate (315 or its derivatives effectively catalyze rapid and efficient hydrolysis.6 In contrast, the phosphonothioate agent, VX(4), was reported

Kinetics and mechanisms of the reactions of benzoyl derivatives of nucleophiles: dependence of the solvation requirement of the reaction on the structures of the nucleophile and the acyl group

“…8 The three buffers employed were Imz, the oiodosobenzoate anion, Iba, and monohydrogenphosphate dianion, Phos. Our interest in these buffers is due to the following reasons: (i) although their pK a values are similar, namely 7.53, 7.05 and 7.20 for Iba, Imz and Phos, respectively, their catalytic efficiencies (in ester hydrolysis) are very different, IBA > Imz ) Phos; 8d (ii) Iba is a powerful nucleophile, with potential use in largescale decontamination of toxic chemical substances and wastes, including phosphorelated pesticides and chemical warfare agents; [11][12][13] (iii) to our knowledge, there is no information on the kinetics and mechanism of the hydrolysis of ArCO-Iba.…”

Treatability Study Report for Remediation of Chemical Warfare Agent Contaminated Soils Using Peroxysulfate Ex-Situ Treatment.

“…7 However, peroxymonosulfate does not oxidize GB unless catalyzed. 9 Peroxydisulfate completely mineralizes HD`° and VX," as well as GB simulants such as DIMP and DMMP. 5…”

Decomposition of O,S-dimethyl methylphosphonothiolate by ammonia on magnesium oxide: a theoretical study of catalytic detoxification of a chemical warfare agent

“…In our earlier study, 49 we have explored the aminolysis of DMPT without any metal-oxide support. [7][8][9] The objective of the present work is to explore the complete reaction mechanism of DMPT degradation in all possible pathways which will facilitate further experimental and theoretical studies on large or bulk metal oxide systems. Here, we have used cluster models like Mg 16 In this work, we have considered different modes of DMPT adsorption on the MgO surface via different adsorption centers prior to detoxification.…”

“…[4][5][6] In this regard, the compound O,S-dimethyl methylphosphonothiolate (DMPT) is an analogue of the chemical warfare agent, VX, due to its P-O and P-S linkages that have similar hydrolytic labilities. [7][8][9] Much effort has been devoted towards the degradation of organophosphorus compounds (OPC) through different processes such as hydrolysis, [10][11][12] oxidation, 13 photolysis, 14 biodegradation 15 as well as treatment with a-nucleophiles 16,17 to produce non-toxic products. A number of theoretical investigations were performed for the thermal unimolecular decomposition, 18 hydrolysis, 19 and a-nucleophilic destruction 20 of such deadly agents.…”

“…Throughout DMPT degradation, P-S scission is an important aspect as it yields a less toxic product. [7][8][9] The objective of the present work is to explore the complete reaction mechanism of DMPT degradation in all possible pathways which will facilitate further experimental and theoretical studies on large or bulk metal oxide systems.…”