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Aminolyses of 2,4-dinitrophenyl 2-furoate and benzoate: Effect of nonleaving group on reactivity and mechanism

Title
Aminolyses of 2,4-dinitrophenyl 2-furoate and benzoate: Effect of nonleaving group on reactivity and mechanism
Authors
Um I.-H.Chun S.-M.Akhtar K.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2007
Journal Title
Bulletin of the Korean Chemical Society
ISSN
0253-2964JCR Link
Citation
vol. 28, no. 2, pp. 220 - 224
Indexed
SCI; SCIE; SCOPUS; KCI WOS scopus
Abstract
Second-order rate constants (kN) have been determined spectrophotometrically for reactions of 2,4-dintrophenyl 2-furoate (2) with a series of alicyclic secondary amines in 80 mol % H2O/20 mol % dimethyl sulfoxide (DMSO) at 25.0°C. The furoate 2 is more reactive than 2,4-dintrophenyl benzoate (1) toward all the amines studied. The higher acidity of 2-furoic acid (pKa = 3.16) compared with benzoic acid (pK a = 4.20) has been suggested to be responsible for the reactivity order, at least in part. The Brønsted-type plots for the reactions of 1 and 2 are curved downwardly, indicating that the aminolyses of both 1 and 2 proceed through a zwitterionic tetrahedral intermediate (T±) with a change in the rate-determining step on changing the amine basicity. Dissection of the kN values into their microscopic rate constants has revealed that the pKa° and k2/k-1 ratios for the reactions of 1 and 2 are identical, indicating that the nature of the nonleaving group (i.e., benzoyl and 2-furoyl) does not affect the reaction mechanism. The k1 values have been found to be larger for the reactions of 2 than for those of 1, which is fully responsible for the fact that the former is more reactive than the latter.
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자연과학대학 > 화학·나노과학전공 > Journal papers
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