Graphical Determination of Monomer Shift,Dimer Shift and Dimerization Constant for Self-Association: 2-Isopropyl Phenol in C6D12 as an Example

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.