ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Study of acid hydrolysis of some substituted derivatives of 3-phenyliminoxindole

D. Kalavská, S. Kalavský, A. Košturiak, and A. Szaló

Department of Analytical Chemistry, Faculty of Natural Sciences, Komenský University, 816 50 Bratislava

Abstract:  The hydrolysis of ten substituted derivatives of 3-phenyliminoxindole in the pH region 2.5—5.0 and in the temperature range 10—80°C is described. The reaction kinetics was investigated spectrophotometrically in the region 300—800 nm within the concentration range 1 x 10^-4—6 x 10^-4 M in the presence of 15 volume % of 1-propanol. The overall rate constants as well as the rate constants of noncatalyzed and by the H⁺ ion catalyzed process were determined. The critical concentrations of catalyst were calculated. The activation parameters of the overall reaction and catalyzed hydrolysis were determined. The effect of substituent on the rate and course of hydrolysis was investigated. It has been proved that the acid hydrolysis of the derivatives of 3-phenyliminoxindole is a first-order reaction in the whole investigated range of temperature, concentration, and pH. The results of acid-catalyzed hydrolysis are confronted with the results obtained in the study of base-catalyzed hydrolysis and a view on the mechanism of hydrolytic reactions in the whole pH range is put forward.

Full paper in Portable Document Format: 325a650.pdf

Chemical Papers 32 (5) 650–657 (1978)