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Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism

Title
Nucleophilic Substitution Reactions of 2,4-Dinitrophenyl X-Substituted-Benzenesulfonates and Y-Substituted-Phenyl 4-Nitrobenzenesulfonates with Azide Ion: Regioselectivity and Reaction Mechanism
Authors
Moon J.-H.Kim M.-Y.Han S.-Y.Um I.-H.
Ewha Authors
엄익환한소엽
SCOPUS Author ID
엄익환scopusscopus; 한소엽scopus
Issue Date
2015
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
vol. 36, no. 5, pp. 1360 - 1365
Keywords
Aryl benzenesulfonatesAzidolysisRegioselectivityS<inf>N</inf>Ar reactionYukawa-Tsuno plot
Publisher
Korean Chemical Society
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
The second-order rate constants for reactions of 2,4-dinitrophenyl X-substituted-benzenesulfonates (4a-4f) and Y-substituted-phenyl-4-nitrobenzenesulfonates (5a-5f) with N<inf>3</inf>- ion have been measured spectrophotometrically. The reactions of 4a-4f proceed through S-O and C-O bond fission pathways competitively. Fraction of the S-O bond fission decreases rapidly as the substituent X in the benzenesulfonyl moiety changes from an electron-withdrawing group to an electron-donating group. The Hammett plots for reactions of 4a-4f are linear with ρ<inf>X</inf>=1.87 and 0.56 for the S-O and C-O bond fission, respectively. The fact that the substituent X is further away from the reaction site of the C-O bond fission than that of the S-O bond fission is one reason for the smaller ρ<inf>X</inf> value. The nature of the reaction mechanism (i.e., a stepwise mechanism in which expulsion of the leaving group occurs after the rate-determining step) is also responsible for the smaller ρ<inf>X</inf> value obtained from the C-O bond fission. The Brønsted-type plot for the reactions of 5a-5f is linear with β<inf>lg</inf>=-0.63, which is typical for reactions reported previously to proceed through a concerted mechanism. Effects of substituents X and Y on regioselectivity and reaction mechanism are discussed in detail. © 2015 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA.
DOI
10.1002/bkcs.10259
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자연과학대학 > 화학·나노과학전공 > Journal papers
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