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Effect of Amine Nature on Rates and Mechanism: Pyridinolyses of 4-Nitrophenyl Benzoate

Title
Effect of Amine Nature on Rates and Mechanism: Pyridinolyses of 4-Nitrophenyl Benzoate
Authors
Um I.-H.Baek M.-H.Han H.-J.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2003
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
vol. 24, no. 9, pp. 1245 - 1250
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
Pseudo-first-order rate constants (kobs) have been measured spectrophotometrically for the reactions of 4-nitrophenyl benzoate with a series of pyridines in H2O containing 20 mol % DMSO. The plots of kobs vs pyridine concentration are linear up to ca. 0.1 M pyridines, indicating that the effect of self-association of pyridines with their conjugate acids are insignificant in this concentration range. The Brønsted-type plot has been obtained to be linear with a β nuc value 1.11, suggesting that the pyridinolyses proceed through a rate-determining breakdown of the zwiterionic addition intermediate. The pyridines studied have shown higher reactivity than isobasic primary and secondary amines toward the substrate. 1-Benzoyl-4-dimethylamino-pyridinium ion, a possible intermediate, has not been detected since the rate of its hydrolysis in the reaction condition is comparable with or even faster than its formation.
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자연과학대학 > 화학·나노과학전공 > Journal papers
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