SOLVENT INFLUENCE UPON COMPLEX-FORMATION BETWEEN CROWN-ETHERS AND UNPROTONATED AMINES

The complexation reactions of some primary and secondary amines with c rown ethers have been studied by means of calorimetric titrations. Thu s, the stability constants and values of the reaction enthalpies and e ntropies were obtained. The values of the stability constants are near ly identical in all solvents examined. However, the values of the reac tion enthalpies and entropies are influenced by solvation effects. In non-polar solvents such as toluene, cyclohexane, and carbon tetrachlor ide, complex formation with the amines is only favoured by entropic co ntributions. The values of the reaction enthalpies are rather small an d nearly identical in these solvents.