CORRELATIONS OF CRITICAL PROPERTIES WITH COMPUTED MOLECULAR-SURFACE AREAS FOR 11 HOMOLOGOUS SERIES OF 118 ORGANIC-COMPOUNDS

A simple and convenient method for predicting critical constants (T-c, P-c, and V-c) for members of a homologous series was developed from c omputed molecular surface areas obtained from a molecular modeling pro gram (CAChe version 3.5). The best linear correlations are obtained wh en V-c and T-c/P-c(0.5) plotted against computed molecular surface are a (SA) and when T-c and P-c are plotted against the natural logarithm of surface area. In SA, for 11 homologous series with a total of 118 o rganic compounds. The series included n-alkanes, n-alkyl primary amine s, n-alkyl primary alcohols, acetate esters, n-alkyl primary thiols, s econdary alcohols, n-alkylbenzenes, 2-methylalkanes, perfluoroalkanes, methyl esters, and ethyl esters. For C-2-C-19 n-alkanes, the calculat ed T-c (K) values agreed well with the literature critical temperature s (R = 1.000) and with other previously described correlations. Simila r T-c correlations were found with the other 10 homologous series. The correlation between T-c/P-c(0.5) and SA for the 11 homologous series is particularly striking and suggests a strong relationship between mo lecular surface area and intermolecular attractions.