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A mechanistic study on alkaline hydrolysis of Y-substituted phenyl benzenesulfonates

Title
A mechanistic study on alkaline hydrolysis of Y-substituted phenyl benzenesulfonates
Authors
Im L.-R.Park Y.-M.Um I.-H.
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. 12, pp. 2477 - 2481
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
Second-order rate constants (kOH -) have been measured spectrophotometrically for reactions of Y-substituted phenyl benzenesulfonates (1a-h) with OH- in H2O containing 20 mol % DMSO at 25.0 ± 0.1 °C. The Brønsted-type plot is linear with βlg = -0.55 including the points for the reactions of 2,4-dinitrophenyl benzenesulfonate (1a) and 4-chloro-2-nitrophenyl benzenesulfonate (1c), indicating that the ortho-nitro group on the leaving aryloxide does not exert steric hindrance in the current reactions. The Hammett plot correlated with σ° constants exhibits highly scattered points, while the Hammett correlation with σ- constants results in a slightly better correlation but still many points deviate from the linearity. In contrast, the Yukawa-Tsuno plot shows an excellent linear correlation with r = 0.52, implying that leaving-group departure occurs at the RDS either in a stepwise mechanism or in a concerted pathway. However, the stepwise mechanism in which the leaving group departs in the RDS is excluded since the incoming OH- is much more basic and a poorer nucleofuge than the leaving aryloxide. Thus, the alkaline hydrolysis of 1a-h has been concluded to proceed through a concerted mechanism.
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자연과학대학 > 화학·나노과학전공 > Journal papers
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