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

Abstract

AbstractThis study was carried out to show the predictive capacity of the semi‐empirical topological index (IET) in estimating some important physical properties; melting point, Mp (°C), boiling point, Bp (°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 IET. The simple linear regression between RIExp and the IET exhibits high quality with a coefficient of determination of r2 = 0.9995, standard deviation of SD = 8 and leave‐one‐out cross‐validation correlation coefficient of $r_{{\bf cv}}^2 $ = 0.999. The best correlations between experimental melting, Mp (°C), and boiling Bp (°C) points, and I ET were achieved through quadratic polynomial equations. The correlation of Bp (°C) with IET for 86 compounds showed excellent results: r2 = 0.9971, SD = 4.2, $r_{{\bf cv}}^2 $ = 0.997. From this equation the values of 24 compounds not included in the model were calculated (r2 = 0.9931; SD = 7.6). The correlation between Mp (°C) and IET for 43 compounds was very good (r2 = 0.9865; SD = 6.1; $r_{{\bf cv}}^2 $ = 0.985), and experimental values of eight compounds not included in the initial model also showed good correlation with calculated values (r2 = 0.9903; SD = 4.1). Finally, for 19 compounds the correlation between the experimental log p‐value and that calculated using the IET method gave a value of r2 = 0.9871, while the correlation with the value obtained using the most used Fragment Addition Method was r2 = 0.9750. These results show the predictive capacity of the IET for these physical properties. Copyright © 2008 John Wiley & Sons, Ltd.