Kinetic study by UV Spectrophotometry of Carzol degradation in aqueous medium

Abstract

This paper deals with the kinetic hydrolysis in aqueous media of Carzol or (E) 3-dimethylamino- methyleneaminophenyl-N-methylcarbamate hydrochloride. The Carzol is a bifunctional compound which belongs to the chemical families formamidine and carbamate. This work is carried out by UV Spectrophotometry. The successive determination of 3-aminophenyl-N-methylcarbamate and 3-aminophenol, as the mainproducts of the formamidine and the carbamate groups of Carzol hydrolysis gives evidence for the significant reactivity of this insecticide-acaricide in aqueous media. The obtained negative activation entropy ΔS≠= - 32.39 J mol-1K-1 indicates a BAC2 mechanism involving bimolecular collapse of the formamidine group of Carzol. While, the obtained positive activation entropy ΔS≠= +100.24J mol-1 K-1and the absence of basic general catalysis indicate an E1cB mechanism involving unimolecular collapse of the carbamate group of Carzol via a methylisocyanate intermediate.

Kinetic Study and Mechanism Hydrolysis of 4‐Bromo‐3,5 dimethylphenyl N‐methylcarbamate in Aqueous Media

“…The positive value of the activation entropy is in agreement with the mechanism E1cB. Comparable values were obtained for the hydrolysis reaction of a series of N ‐methylcarbamates studied in our laboratory: carbaryl , carbofuran , methiocarb , bendiorab , zectran , aminocarb , landrin , ethiofencarb , carzol , and isoprocarb .…”

“…The corresponding mechanism involves either an addition of OH − into the carbonyl with a further elimination of the RO − leaving group or an abstraction of the hydrogen of the methylcarbamate moiety again evolving with the elimination of the RO − group. Consequently, we have undertaken in our laboratory a study of the determination of both the kinetic and mechanistic aspects of the hydrolysis reaction of carbaryl , carbofuran , methiocarb , bendiocarb , zectran , aminocarb , landrin , ethiofencarb , carzol , isoprocarb , and pirimicarb . We showed that hydrolysis of PNMCs exhibited pseudo–first‐order kinetics with respect to substrate in aqueous media.…”