The reactivity of aliphatic amines and morpholines in dioxane–water solvent systems

Abstract

Using the titration of tertiary aliphatic amines as a model a linear relationship for the log equilibrium constant versus the log dielectric constant over a broad range of dioxane–water mixtures is established. Primary and secondary amines are less responsive to changes in dielectric constant, producing linear data of shallower slope. A study of morpholine and N-alkyl-morpholines produces curves that plateau in high dielectric constant regions and display decreasing slope as water concentrations approach zero. Similar behavior for morpholines is observed in low water mixtures where they form proton transfer complexes with p-nitrophenol. Possible reasons for the behavior are discussed.