Linear free energy relationships in the thiophen series. Part 2. The kinetics of the reactions of some 2-bromo-3-nitro-5-X-thiophens with substituted anilines in methanol

Abstract

The rate constants for the reactions of 2-bromo-3-nitro-5-X-thiophens (X = H, Br, CONH₂, CO₂Me, Ac, SO₂Me, CN, or NO₂) with some substituted anilines YC₆H₄NH₂(Y =p-OMe, p-Me, H, m-Cl, or p-CO₂Me) have been measured in methanol at various temperatures. The sensitivity parameters, ρ(Y) and β(X), obtained from Hammett and Brönsted correlations are practically independent of the reactivity of the starting system. The relevance of these results to the reactivity–selectivity principle is discussed.