SUMMARY
The studies in a series of 2-(benzoylamino)(1-R-2-oxoindoline-3-ylidene) acetic acids and their derivatives have shown that compounds of the isostructural series exhibit the nootropic, antihypoxic, anabolic activity.Aim. To study the reactivity of esters of 2-(benzoylamino)(1-R-2-oxoindoline-3-ylidene) acetic acids.Materials and methods. The concentration of NaOH in the solution was determined by potentiometric titration on an EV-74 ionomer using the standard aqueous HCl solution. The reaction kinetics was performed in triplicates, the experiments contained 6-8 measurements (the depth of the change was not less than 80 %). The accuracy of the results obtained was assessed by the methods of mathematical statistics of small samples with statistical significance of 0.95.Results and discussion. The reaction rate constants of alkaline hydrolysis of esters of 2-(benzoylamino)(1-R-2-oxoindoline-3-ylidene) acetic acids depend on the structure and the length of the hydrocarbon chain at the heterocyclic nitrogen atom. Introduction of hydrocarbon radicals to the structure of the heterocycle slows down the reaction, while the chain extension accelerates it. The effect of the electronic nature of the substituents on the reactivity of ethyl esters was quantitatively assessed by Hammett equation. The data obtained suggest that the values of the reaction parameter ? are positive in the temperature range studied; it is additionally confirmed by the BAC2 mechanism of this reaction.Conclusions. The reaction kinetics of alkaline hydrolysis of biologically active ethyl esters of 2-(benzoylamino) (1-R-2-oxoindoline-3-ylidene) acetic acids has been studied in a wide temperature range; its BAC2 mechanism has been proven with formation of highly symmetrical intermediate. The effect of the substituents at the heterocyclic nitrogen atom on the numerous kinetic and activation parameters of the reaction has been analyzed; isokineticity and synchronicity of the reaction have been proven using independent tests.