Hydrogen bonding. Part 26. The calorimetric acidity scale of Laynez

Abstract

A new acidity scale based on calorimetric measurements of N-methylimidazole and N-methylpyrrole in bulk solvents has been reported by Laynez et al. Although this is claimed to be a solvent acidity scale, it has been incorrectly matched with the solute α₂^H hydrogen-bond acidity parameter of Abraham. When correctly matched to the Kamlet–Taft solvatochromic hydrogen-bond parameter for bulk solvents, α₁, a useful equation can be constructed for the determination of α₁ values by the calorimetric method.