NEW GROUP-CONTRIBUTION METHOD FOR ESTIMATING PROPERTIES OF PURE COMPOUNDS

A new group contribution method for the estimation of properties of pu re organic compounds is presented. Estimation is performed at two leve ls: the basic level uses contributions from first-order groups, while the next higher level uses a small set of second-order groups having t he first-order groups as building blocks. Thus, the method provides bo th a first-order approximation (first-order group contributions) and a more accurate second-order prediction (first- and second-order group contributions). This article discusses methods for prediction of norma l boiling point, normal melting point, critical pressure, critical tem perature, critical volume, standard enthalpy of vaporization at 298 K, standard Gibbs energy, and standard enthalpy of formation at 298 K. T he predictions are based exclusively on the molecular structure of the compound, and the method is able to distinguish among isomers. Compar ed to the currently-used methods, this technique demonstrates signific ant improvements in accuracy and applicability.