Cleavage of VX simulants by micellar iodoso- and iodoxybenzoate

O,S-Diethyl phenylphosphonothioate (5) and S-phenyl (9) and S-ethyl dipheny lthiophosphinate (10) were efficiently cleaved by 3-fold excess o-iodosoben zoate (IBA) in aqueous micellar cetyltrimethylammonium chloride solutions a t pH 9.5. The maximum observed rate constants (monitored by HPLC aliquot pr ocedures) were 1.09 x 10(-3) s(-1) for 5 and 6.0 x 10(-3) s(-1) for 10 with 0.06 M IBA at 25 degrees C. 9 cleaved too rapidly to follow by the aliquot method. With equimolar quantities of 5 and IBA, cleavage was slower and in complete because of the reduction of the IBA to iodobenzoate by the EtSH li berated-in the cleavage step. Mixtures of IBA and o-iodoxybenzoate (IBX) ef ficiently cleaved 5, even though IBX was not reactive toward 5, because the IBX competitively oxidized the EtSH, mitigating its reaction with IBA, whi le simultaneously affording additional IBA as the IBX was reduced. Studies of IBA and IBX redox reactions with EtSH are also included.