Novel application of simple molybdates: Catalytic hydrolysis of an organophosphate neurotoxin under mild aqueous conditions

作者：Kuo Louis Y^*; Dill Kristina M; Shari'ati Yusef A; Bright Emily K; McCormick Theresa

来源：Inorganica Chimica Acta, 2017, 466: 1-7.

DOI：10.1016/j.ica.2017.05.007

A novel protocol for hydrolyzing phosphonothioate neurotoxins has been developed that uses a readily available, inexpensive and non-toxic molybdate (MoO42). The target organophosphate is O,S-diethylphenyl phosphonothioate (1), a model compound that has served as an analog of the chemical warfare agent VX. Molybdate-mediated hydrolysis of 1 proceeds at room temperature (pH similar to 7.5) and yields a relatively safe phosphonate product through P-S specific scission. This is the first report of utilizing the molybdate, MoO42 , to degrade an organophosphate neurotoxin with turnover. A Delta S-double dagger of 81.5 J/mol.K (-19.5 cal/mol.K) indicates a bimolecular process, and O-18-labeling studies show no oxygen exchange of 1 throughout the hydrolysis by MoO42 (aq). We hypothesize primarily the monomeric molybdate is the active species at pH 7.5 where a S(N)2(P) mechanism takes place. Density functional theory methods suggest the molybdate oxoanion serves as the nucleophile to attack phosphonothioate 1 to form a molybdate-phosphonate anhydride that subsequently hydrolyzes to the starting molybdate and phenylethyl phosphonate.

• 出版日期2017-9