Thermodynamic parameters for the basic ionization of some cyclic amines in water

Abstract

The thermodynamic parameters defining the basic dissociation in water of diethylamine, cyclohexylamine, piperidine, and quinuclidine have been determined by a dilution method based on conductance measurements. The values of ΔSa0 and ΔCpa0 for the acid ionization of the corresponding ammonium ions at 25 °C are ΔSa0 −8.08, −1.24, −8.51, −13.65 cal deg−1 mol−1 and ΔCpa0 13.9, −2.7, 18.0, 4.2 cal deg−1 mol−1. The relation between these derived values and solvation changes are discussed, the apparent anomalous values of ΔCpa0 for cyclohexylamine and quinuclidine being noted, but not rationalized.