Reactions of 2,4-Dinitrophenyl 5-substituted-2-thiophenecarboxylates with R2NH/R2NH2 + in 20 Mol % DMSO(aq). Effects of 5-Thienyl Substituent and Leaving Group on the Reaction Mechanism

Sang Yong Pyun, Kyu Cheol Paik, Man So Han, Bong Rae Cho

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Reactions of 2,4-dinitrophenyl 2-thiophenecarboxylate (2a–d) with R2NH/R2NH2 + in 20 mol % DMSO(aq) have been studied. The reactions are overall second order, first order to the substrates, and first order to the nucleophiles. The Brönsted plots showed downward curves with pKa 0 = 9.5, β1 = 0.22–0.34, and β2 = 0.85–0.92. The k1 values increased with a stronger electron-withdrawing 5-thienyl substituent and a stronger nucleophile, whereas the k2/k−1 values remained nearly the same for all 5-thienyl substituents. The influence of 5-thienyl substituent on the reaction rates showed excellent correlations on the Yukawa-Tsuno plots with ρ = 1.28–2.16 and r = 0.20–0.60. The ρ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the carbonyl carbon and a decrease in the resonance demand. From these results, a stepwise mechanism with a change in the rate-determining step has been proposed.

Original languageEnglish
Pages (from-to)983-990
Number of pages8
JournalBulletin of the Korean Chemical Society
Issue number10
Publication statusPublished - 2019 Oct 1


  • Aminolysis
  • Bronsted-plot
  • Hammett plot
  • Yukawa-Tsuno plot

ASJC Scopus subject areas

  • Chemistry(all)


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