| The applications of computer-assisted methodology to investigate structure-property relationships for polyhalogenated biphenyls are described. Multiple linear regression methods were used to correlate the properties of these compounds with descriptors encoding structural characteristics of the molecules. In the first study, gas chromatographic retention times of polychlorinated biphenyls (PCBs) were predicted by using simple molecular structure descriptors. Two excellent equations with ;The methodology was also applied to the prediction of Henry's law constants (HLC) of PCBs. HLCs were predicted using two methods. The first method involved development of a single equation which directly related HLCs with molecular structures, while the second method involved a two-step procedure in which the solubility and the vapor pressure were first predicted and HLCs were obtained from the ratio of two quantities. Using the first method, a five-variable equation containing descriptors which encode the size, shape and polarizability of the molecules were developed. It was observed that HLCs calculated from the single equation were closer to experimental values than those calculated from the ratio of vapor pressure and solubility.;The third study involved prediction of gas and liquid chromatographic retention indices of polyhalogenated biphenyls. Excellent equations with high degree of statistical significance were developed for both data sets. For gas chromatography, descriptors encoding the size and general shape of the molecules were found important in predicting their retention indices, while for liquid chromatography, charge-weighted surface areas were among the important descriptors in the models. Probably because more interactions were involved, the models for LC were not as good as those for GC. |
