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Aminolysis of 3,4-dinitrophenyl cinnamate and benzoate 2: Activation parameters and transition-state structures

Title
Aminolysis of 3,4-dinitrophenyl cinnamate and benzoate 2: Activation parameters and transition-state structures
Authors
Um I.-H.Park Y.-M.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2008
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
vol. 29, no. 3, pp. 575 - 579
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
The apparent second-order rate constants (kN) have been dissected into the microscopic rate constants (i.e., k1 and k 2/k-1) associated with the reactions of Y-substituted phenyl cinnamates (5a-g) with piperidine and morpholine on the assumption that the reactions proceed through a stepwise mechanism with a change in the rate-determining step (RDS). The k1 value is larger for the reactions with the more basic piperidine, and increases with decreasing the basicity of the leaving aryloxides. However, the k2/k-1 ratio is almost the same for the reaction of 3,4-dinitrophenyl cinnamate (5a) with piperidine and for that with morpholine, which is not possible if the reactions proceed through a stepwise mechanism. Thus, the aminolysis of 5a-g has been proposed to proceed through a concerted mechanism. The activation parameters (ΔH‡ and ΔS‡) have been measured for the reactions of 3,4-dinitrophenyl benzoate (1a) and cinnamate (5a) with morpholine from the kinetic study performed at 5 different temperatures in 80 mol % H2O/20 mol % DMSO. The reaction of 5a results in a lager enthalpy of activation (ΔH‡) but a less negative entropy of activation (ΔS‡) than that of 1a.
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자연과학대학 > 화학·나노과학전공 > Journal papers
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