GRAPHICAL DETERMINATION OF MONOMER SHIFT, DIMER SHIFT AND DIMERIZATION CONSTANT FOR SELF-ASSOCIATION - 2-ISOPROPYL PHENOL IN C6D12 AS AN EXAMPLE

Abstract

We propose a graphical method to treat dilution shift in NMR spectra to determine the monomer shift, dimer shift and dimerization constant simultaneously and consistently for the system of monomer/dimer equilibrium. The salient features include avoiding error-prone manual extrapolation to zero concentration to obtain a monomer shift, and providing consistent assessment and error estimation for the determination. The dilution shifts of 2-isopropyl phenol in C6D12 serve to demonstrate this graphical method. The enthalpy and entropy of dimerization are determined via a van't Hoff plot from the temperature variation of the dimerization constant.