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A kinetic study on ethylaminolysis of phenyl y-substituted-phenyl carbonates: Effect of leaving-group substituents on reactivity and reaction mechanism

Title
A kinetic study on ethylaminolysis of phenyl y-substituted-phenyl carbonates: Effect of leaving-group substituents on reactivity and reaction mechanism
Authors
Song Y.-J.Kim M.-Y.Um I.-H.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2013
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
vol. 34, no. 6, pp. 1722 - 1726
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
A kinetic study on nucleophilic substitution reactions of phenyl Y-substituted-phenyl carbonates (5a-5j) with ethylamine in 80 mol % H2O/20 mol % DMSO at 25.0 ± 0.1 oC is reported. The plots of kobsd vs. [amine] are linear for the reactions of substrates possessing a strong electron-withdrawing group (EWG) but curve upward for those of substrates bearing a weak EWG, indicating that the electronic nature of the substituent Y in the leaving group governs the reaction mechanism. The reactions have been concluded to proceed through a stepwise mechanism with one or two intermediates (a zwitterionic tetrahedral intermediate T± and its deprotonated form T-) depending on the nature of the substituent Y. Analysis of Brønsted-type plots and dissection of kobsd into microscopic rate constants have revealed that the reactions of substrates possessing a strong EWG (e.g., 5a-5f) proceed through T± with its formation being the rate-determining step, while those of substrates bearing a weak EWG (e.g., 5g-5j) proceed through T± and T-.
DOI
10.5012/bkcs.2013.34.6.1722
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자연과학대학 > 화학·나노과학전공 > Journal papers
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