Kinetic Studies of Alkaline Hydrolysis of Methyl-2-[2'-oxo-3'-(2'-chloro-6'fluorophenyl)propyl]benzoate and Methyl-2-benzoylmethylbenzoate in Aqueous and EtOH-H_2O Media

摘要

The hydrolysis of the compound,methyl-2-[2'-oxo-3'-(2"-chloro-6"-fluoro-phenyI)propyl]benzoate has been studied spectrophotometrically in the presence of hydroxide ions in aqueous,25 % and 50 %(V/V)EtOH-H_2O mixtures.The dependence of pseudo-first order rate constant k_(obs)on hydroxide ion concentration is fitted by the expression k_(obs),=k_o + k_i[OH] +k_2[OH]~2,showing the formation of monoanionic and dianionic tetrahedral intermediates during the course of reaction.The magnitude of k_o shows significant participation of solvent in the reaction mechanism which goes on decreasing with increasing concentration of ethanol in the solvent mixture.The hydrolysis of methyl-2-benzoylmethyl-benzoate has also been studied in aqueous medium in the presence of different hydroxide ion concentrations and results were compared with the former ester.