Steric and electronic effects to interpret non-covalent interactions in binary mixtures of dimethyl carbonate and isomeric cresols through thermophysical, acoustic and spectroscopic studies

Abstract

The densities (ρ), viscosities (η) and ultrasonic velocities (u) were measured for the binary mixtures of dimethyl carbonate (DMC) and isomeric cresols viz., o-cresol, m-cresol, p-cresol over the entire range of composition at atmospheric pressure and at different temperatures (303.15, 308.15,313.15, 318.15) K. From these experimental results, excess molar volume $$(V_{\text{m}}^{\text{E}} )$$ , deviation in adiabatic compressibility (Δβ ad), excess intermolecular free length ( $$L_{\text{f}}^{\text{E}}$$ ), excess acoustic Impedance (Z E), deviation in viscosity (Δη), excess Gibbs free energy of activation of viscous flow $$\left( {\Delta G^{{*{\text{E}}}} } \right)$$ and excess enthalpy ( $$H^{\text{E}}$$ ) have been calculated. The excess or deviation properties were fitted to Redlich–Kister polynomial equation to obtain their coefficients and standard deviations. The excess or deviation properties were found to be either negative or positive depending on the molecular interactions between the components of hetero molecules, and the nature of liquid mixtures has been discussed in terms of molecular interactions through steric and electronic effects. To know more about solute–solvent interactions, partial molar volumes ( $$\bar{V}_{{{\text{m}},1}} ,\bar{V}_{{{\text{m}},2}}$$ ) and excess partial molar volumes ( $$\bar{V}_{{{\text{m}},1}}^{\text{E}} , \bar{V}_{{{\text{m}},2}}^{\text{E}}$$ ) have been computed. Further, variation of excess molar enthalpy with pressure is also evaluated to elucidate the molecular interactions in the liquid mixture. The present investigation also comprises of evaluation of the acoustic nonlinearity parameter (B/A) in the mixtures and calculation of cohesive energy (ΔA), Van der Wall’s constants (a, b), distance of closest approach (d). The FTIR provides support to the thermodynamic findings to explain specific interaction between unlike molecules.