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Mechanistic assessment of S NAr displacement of halides from 1-Halo-2,4-dinitrobenzenes by selected primary and secondary amines: Brønsted and Mayr analyses

Title
Mechanistic assessment of S NAr displacement of halides from 1-Halo-2,4-dinitrobenzenes by selected primary and secondary amines: Brønsted and Mayr analyses
Authors
Um I.-H.Im L.-R.Kang J.-S.Bursey S.S.Dust J.M.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2012
Journal Title
Journal of Organic Chemistry
ISSN
0022-3263JCR Link
Citation
vol. 77, no. 21, pp. 9738 - 9746
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
Pseudo-first-order rate constants (k obsd) have been measured spectrophotometrically for nucleophilic substitution reactions of 1-X-2,4-dinitrobenzenes (1a-d, X = F, Cl, Br, I) with various primary and secondary amines in MeCN and H 2O at 25.0 ± 0.1 °C. The plots of k obsd vs [amine] curve upward for reactions of 1a (X = F) with secondary amines in MeCN. In contrast, the corresponding plots for the other reactions of 1b-d with primary and secondary amines in MeCN and H 2O are linear. The Brønsted-type plots for reactions of 1a-d with a series of secondary amines are linear with β nuc = 1.00 for the reaction of 1a and 0.52 ± 0.01 for those of 1b-d. Factors governing reaction mechanisms (e.g., solvent, halogen atoms, H-bonding interactions, amine types) have been discussed. Kinetic data were also analyzed in terms of the Mayr nucleophilicity parameter for the amines with each aromatic substrate. Provisional Mayr electrophilicity parameter (E) values for 1-X-2,4-dinitrobenzenes have been determined: E = ?14.1 for X = F, E = ?17.6 for X = Cl and Br, and E = ?18.3 for X = I. These values are consistent with the range and order of E values for heteroaromatic superelectrophiles and normal 6-? aromatic electrophiles. © 2012 American Chemical Society.
DOI
10.1021/jo301862b
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자연과학대학 > 화학·나노과학전공 > Journal papers
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