Ion pairing in alkali-metal salts of 1,3-diphenylalkenes. Part II. The determination of equilibrium constants from absorption spectra

Abstract

The existence of contact ion pairs (C) and solvent-separated ion pairs (SS) is well established in solutions of alkalimetal salts of carbanions. We present results for the alkali-metal salts of 1,3-diphenylpropene and 1,3-diphenylbut-1-ene which indicate that two kinds of contact ion pair exist in these systems: a poorly solvated contact ion pair (C₁) and a more highly solvated contact ion pair (C₂). The thermodynamic parameters ΔH° and ΔS° have been determined, in appropriate cases, for the processes C₁→ C₂ and C₂→ SS.