A molecular equation of state for alcohols which includes steric hindrance in hydrogen bonding

In this paper we develop the first equation of state for alcohol containing mixtures which includes the effect of steric hindrance between the two electron lone pair hydrogen bond acceptor sites on the alcohol's hydroxyl oxygen. The theory is derived for multi-component mixtures within Wertheim's multi-density statistical mechanics in a second order perturbation theory. The accuracy of the new approach is demonstrated by application to pure methanol and ethanol and binary ethanol / water mixtures. It is demonstrated that the new approach gives a substantial improvement in the prediction of hydrogen bond structure of both pure alcohol and alcohol / water mixtures as compared to standard first order approaches.