Solvent Effect on the Kinetics of Ring Opening of Isatin in Water–Ethanol Mixtures

Abstract

The kinetics of amide bond cleavage of isatin and N-methylisatin in the presence of ethanol was followed spectrophotometrically in the ranges of solvent composition (0-70%v/v) and temperature (40-60°C) using piperidine as a nucleophile. The reaction proceeds according to pseudo first-order kinetics. The rate of reaction strongly decreased with increasing organic solvent content. The thermodynamic activation parameters were calculated and discussed in terms of solvation. No linearity was observed between log (rate constant) and reciprocal dielectric constant for the solvent used, suggesting that there is selective solvation by the more polar water. The reactivity was analysed in the light of various simple and multiple regression equations using Kamlet–Taft solvatochromic parameters which were applied successfully to the mixed aqueous - ethanol mixtures. Finally, a mechanism for the ring opening is proposed

Kinetic studies on N‐Mannich bases of 3‐hydrazonoindolin‐2‐one in water–ethanol and water–acetonitrile mixtures

“…1, in the case of aqueous ethanol, were the result of the changeover from enhancement of water structure that was caused by the addition of a small amount of ethanol to water to the disruption of the solvent structure at the higher ethanol concentration. At this mole fraction, many physical properties were changed as previously reported [14].…”

“…Schiff and Mannich bases of isatin have gained major interest as potential anti‐TB derivatives. Furthermore, because of the importance of the subject and my continuous studies of the solvent effect on the reaction rate 8–14, kinetic studies of this reaction were carried out.…”

“…Furthermore, because of the importance of the subject and my continuous studies of the solvent effect on the reaction rate [8][9][10][11][12][13][14], kinetic studies of this reaction were carried out.…”

Electrochemical and computational analysis of solvent effects on the kinetics of reaction of nitrite ion with o-quinone

“…Previous works have shown solvent effects on the stability of reactants and product as well as the transition states of reactions [1,2]. It has also been shown that among solvent properties, solvation, hydrogen bond donating/accepting ability and dielectric constant, as well as polarity, can have a large impact on the rate of reaction [3].…”

Solvent Effects on the Kinetic and Mechanism of N-Mannich Bases of 3-Hydrazonoindole-2-one

“…Schiff and Mannish bases of isatin derivatives were reported to show variety of biological activities like antibacterial 4 , antifungal 5 , anticonvulsant 6 , anti HIV 7 , antidepressant 8 and antiinflammatory 9 activities. Because of the importance of the subject and as our continuation studies in the field of solvent effect on reaction rate [10][11][12][13][14][15][16][17][18] , it was, therefore, as a matter of interest to submit this reaction to kinetic studies. The kinetics were measured in mixed solvent media of water with ethanol and water with acetonitrile (up to 70 %), where, pH of the medium was ca.…”