NMR study of ε-caprolactam in various solvents. Graphical determination of monomer shift, dimer shift and dimerization constant from the dilution shift data

Abstract

A graphical method for the simultaneous determination of the monomer shift, dimer shift and dimerization constant of a self-association system from the dilution NMR shift data is proposed. This method avoids the conventional extrapolation to infinite dilution to obtain the monomer shift. Three self-association systems: ε-caprolactam in [²H₁]chloroform, [²H₆]acetone and [²H₃]acetonitrile were studied at various temperatures. The enthalpy and entropy of dimerization were also determined from van't Hoff plots.