Kinetics and mechanism of hydrolysis of insecticidal O-(methylcarbamoyl)oximes

Inhibition of acetylcholinesterase by O-(methylcarbamoyl) oximes. Structure-activity relationships

“…Since the bimolecular rate constant k08 is susceptible to electronic substituent effects (Mrlina and Calmon, 1980) n = 6, s = 0.315, r = 0.888 It can be pointed out that the correlation coefficients are not as high as those obtained for of log k oH against <1 (Mrlina and Calmon, 1980). However, their order of magnitude is significant enough and does not preclude the possible use of k oH instead of <1. relatively high value of the correlation coefficient may suggest that the behavior of the serine hydroxyl of acetylcholinesterase toward O-(methylcarbamoyl)oximes is, in a first step, analogous to that of the hydroxide ion in the alkaline hydrolysis.…”

“…An alternative explanation for the düference between O-(methy lcarbamoyl) benzaldoximes and O-(methyl carbamoyl)acetophenoximes might be the tendency for the former to be converted to the corresponding benzonitriles. The investigation of the alkaline hydrolysis of O-(me thylcarbamoyl)-syn-benzaldoximes gave no evidence for the involvement of such a reaction (Mrlina and Calmon, 1980). However, such a conversion was reported by Payne et al (1966) as a side reaction in the alkaline hydrolysis of aldicarb and might therefore occur at the level of the catalytic site of acetylcholinesterase.…”

“…The results from the limited amount of data used in this investigation indicate that the anticholinesterase activity of substituted O-(methylcarbamoyl)oximes depends largely on the reactivity of the molecule as estimated by the bi molecular rate constant k o H and the free-energy parameter rr. The occurrence of the imine bond between the ester oxygen atom and the phenyl ring does not result in a change-over in the mechanism of alkaline hydrolysis al though the Hammett p value is different from those usually observed for phenyl carbamates (Mrlina and Calmon, 1980). The kinetic investigation of the alkaline hydrolysis of O-(methylcarbamoyl)oximes therefore allowed the p values found in structure-activity relationships (log 1/1 50 vs. u) to be better understood.…”

“…The bimolecular rate constants k o H = k 0bod /[OH-J were determined graphically from the plots of the observed pseudo-first-order rate constant k 0oe<1 against hydroxide ion concentration for the alkaline hydrolyses of O-(methyl carbamoyl)benzaldoximes and -acetophenoximes (Mrlina and Calmon, 1980).…”

Synthesis, Spectroscopic, Structural and Quantum Chemical Studies of a New Imine Oxime and Its Palladium(II) Complex: Hydrolysis Mechanism

“…Depuy and Ponder reported that the hydrolysis of various oximes in the presence of levulinic acid produced the corresponding carbonyl compounds [16]. The hydrolysis of O -(methylcarbamoyl)oximes in basic solutions was studied by Mrlina and Calmon [17]. In addition, the conversion of oximes into their parent carbonyl compounds was achieved by metal ion-assisted hydrolysis [18,19,20].…”