GRAPHIC METHOD FOR THE DETERMINATION OF THE COMPLEX NMR SHIFT AND EQUILIBRIUM-CONSTANT FOR A HETERO-ASSOCIATION ACCOMPANYING A SELF-ASSOCIATION

Abstract

A novel graphic method to determine the complex shift and equilibrium constant for a hetero-association, A + B reversible arrow AB, accompanying a self-association A + A reversible arrow A(2), has been described. The method is to be used in conjunction with a graphic determination of the monomer shift, dimer shift and dimerization constant proposed previously. Our new method is advantageous over the conventional Benesi-Hildebrand (BH) plot in that the limitations, (1) that the concentration of one component must be much less than that of the other and (2) that self-association of species is not allowed, are completely removed. The related parameters of the self-association of 2-isopropylphenol (A) and the hetero-association of 2-isopropylphenol with acetone (B) in the inert solvent [H-2(12)]cyclohexane has been used to demonstrated the use of this new graphic method. Comparison with the results from a BH plot has also been made.