Abstract: Considering the close relationship between the evaporation loss and boiling point of base oil at lower pressure and the shortcomings of existing analysis methods, the structures of 106 kinds of alkylaromatics and their boiling points at 1 333.22 Pa were collected. Based on the data, the Eigenvalues of microstructures such as energies of frontier obitals and charge distributions and topological indexes were calculated by molecular simulation method. GFA method was selected to elucidate the relationship between the structures of alkyl aromatics and their boiling points at 1333.22Pa pressure, resulting in a quantitative equation with the square of correlation coefficient of 0.978 and the square of cross-validated coefficient of 0.962, which means that the equation has a strong predictability for boiling points of alkylaromatics at 1333.22Pa pressure, so as for its evaporation loss. The equation has clear physical meanings, which showed that LUMO-HOMO gap，molecular polarizability, and radius of gyration of alkyl aromatics were the three main structural parameters for prediction of boiling point at 1333.22Pa pressure. The narrower the LUMO-HOMO gap, the higher the molecular polarizability and the larger the radius of gyration, then the higher the boiling point at 1333.22Pa pressure, the greater the evaporation difficulty and the lower the evaporation loss. The established equation with these three structural parameters could be used to predict the boiling points of alkyl aromatics at 1333.22Pa pressure accurately.

Key words: alkylaromatics, structural parameter, evaporation loss, boiling point, quantitative relationship