Semi-empirical topological index to predict properties of halogenated aliphatic compounds

This study was carried out to show the predictive capacity of the semi-empirical topological index (I-ET) in estimating some important physical properties; melting point, Mp(degrees C), boiling point, Bp (degrees C), and experimental log p of halogenated aliphatic hydrocarbons. The retention index (RI) values of 141 compounds were used in the building of this specific model of the I-ET. The simple linear regression between RIExp and the I-ET exhibits high quality with a coefficient of determination of r(2) = 0.9995, standard deviation of SD = 8 and leave-one-out cross-validation correlation coefficient of r(cv)(2) = 0.999. The best correlations between experimental melting, Mp (degrees C), and boiling Bp (degrees C) points, and I-ET were achieved through quadratic polynomial equations. The correlation of Bp (degrees C) with I-ET for 86 compounds showed excellent results: r(2) = 0.9971, SD = 4.2, r(cv)(2) = 0.997. From this equation the values of 24 compounds not included in the model were calculated (r(2) = 0.9931; SD = 7.6). The correlation between Mp (degrees C) and I-ET for 43 compounds was very good (r(2) = 0.9865; SD = 6.1; r(cv)(2) = 0.985), and experimental values of eight compounds not included in the initial model also showed good correlation with calculated values (r(2) = 0.9903; SD = 4.1). Finally, for 19 compounds the correlation between the experimental log p-value and that calculated using the I-ET method gave a value of r(2) = 0.9871, while the correlation with the value obtained using the most used Fragment Addition Method was r(2) = 0.9750. These results show the predictive capacity of the IET for these physical properties. Copyright (c) 2008 John Wiley & Sons, Ltd.