New method to analyse IR-studies of monomer-dimer self-association: 2,2-dimethyl-3-ethyl-3-pentanol in carbon disulfide as an example

Abstract

Two new equations have been derived to treat the IR data from the monomer-dimer self-association. Equation (9), in the text, is to regress the integrated absorbances of the monomer bands to determine the molar absorptivity of the monomer band, epsilon(m), and the dimerization constant, K. Equation (13), in the text, is to regress those of dimer band to obtain the molar absorptivity of the dimer band, epsilon(d), and dimerization constant K. The self-association in the dilute solution of 2,2-dimethyl-3-ethyl-3-pentanol in carbon disulfide at different temperatures has been used as an example to demonstrate the usage of these two equations. The discrepancy between the values of K at the same temperature determined either from the monomer band or from the dimer band can be used as a criterion for the goodness of determination. The standard enthalpy and entropy of dimerization have also been obtained via a van't Hoff plot from the data of K at different temperatures. The advantages of this new approach have also been discussed.