Reactions of 4-nitrophenyl 2-thiophenecarboxylates with R 2NH/R2NH2+ in 20 mol % DMSO (aq). Effects of 5-thienyl substituent and base strength

Sang Yong Pyun, Bong Rae Cho

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3 Citations (Scopus)

Abstract

Reactions of 4-nitrophenyl 2-thiophenecarboxylate (1a-e) with R 2NH/R2NH2+ in 20 mol % DMSO (aq) have been studied kinetically. The 2nd order kinetics, βnuc = 0.88-0.98, and linear Hammett and Yukawa-Tsuno plots observed for these reactions indicate an addition-elimination mechanism in which the 2nd step is rate limiting. The βnuc value increased with a stronger electron-withdrawing 5-thienyl substituent, the Hammett plots are linear except for X = MeO, and Yukawa-Tsuno plots are linear with ρ = 0.79-1.32 and r = 0.28-0.93, respectively. The ? value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the C=O bond and a decrease in the resonance demand. These results have been interpreted with enhanced N-C bond formation in the transition state with the reactivity increase.

Original languageEnglish
Pages (from-to)2036-2040
Number of pages5
JournalBulletin of the Korean Chemical Society
Volume34
Issue number7
DOIs
Publication statusPublished - 2013 Jul 20

Keywords

  • Aminolysis
  • Brönsted-type plot
  • Hammett plot
  • Yukawa-Tsuno plot

ASJC Scopus subject areas

  • Chemistry(all)

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