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Um IH, Hong JY, Kim JJ, et al. Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines. J Org Chem. 2003;68(13):5180-5doi: 10.1021/jo034190i.
Um, I. H., Hong, J. Y., Kim, J. J., Chae, O. M., & Bae, S. K. (2003). Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines. The Journal of organic chemistry, 68(13), 5180-5. https://doi.org/10.1021/jo034190i
Um, Ik-Hwan, et al. "Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines." The Journal of organic chemistry vol. 68,13 (2003): 5180-5. doi: https://doi.org/10.1021/jo034190i
Um IH, Hong JY, Kim JJ, Chae OM, Bae SK. Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines. J Org Chem. 2003 Jun 27;68(13):5180-5. doi: 10.1021/jo034190i. PMID: 12816474.
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J Org Chem. 2003 Jun 27;68(13):5180-5. doi: 10.1021/jo034190i.

Regioselectivity and the nature of the reaction mechanism in nucleophilic substitution reactions of 2,4-dinitrophenyl X-substituted benzenesulfonates with primary amines.

The Journal of organic chemistry

Ik-Hwan Um, Jin-Young Hong, Jung-Joo Kim, Ok-Mi Chae, Sun-Kun Bae

Affiliations

  1. Department of Chemistry, Ewha Womans University, Seoul 120-750, Korea. [email protected]

PMID: 12816474 DOI: 10.1021/jo034190i

Abstract

Second-order rate constants have been measured for the reaction of 2,4-dinitrophenyl X-substituted benzenesulfonates with a series of primary amines. The nucleophilic substitution reaction proceeds through competitive S-O and C-O bond fission pathways. The S-O bond fission occurs dominantly for reactions with highly basic amines or with substrates having a strong electron-withdrawing group in the sulfonyl moiety. On the other hand, the C-O bond fission occurs considerably for the reactions with low basic amines or with substrates having a strong electron-donating group in the sulfonyl moiety, emphasizing that the regioselectivity is governed by both the amine basicity and the electronic effect of the sulfonyl substituent X. The apparent second-order rate constants for the S-O bond fission have resulted in a nonlinear Brønsted-type plot for the reaction of 2,4-dinitrophenyl benzenesulfonate with 10 different primary amines, suggesting that a change in the rate-determining step occurs upon changing the amine basicity. The microscopic rate constants (k(1) and k(2)/k(-)(1) ratio) associated with the S-O bond fission pathway support the proposed mechanism. The second-order rate constants for the S-O bond fission result in good linear Yukawa-Tsuno plots for the aminolyses of 2,4-dinitrophenyl X-substituted benzenesulfonates. However, the second-order rate constants for the C-O bond fission show no correlation with the electronic nature of the sulfonyl substituent X, indicating that the C-O bond fission proceeds through an S(N)Ar mechanism in which the leaving group departure occurs rapidly after the rate-determining step.

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