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

Abstract

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 (-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 I ET . The simple linear regression between RI Exp and the I ET exhibits high quality with a coefficient of determination of r 2 ¼ 0.9995, standard deviation of SD ¼ 8 and leave-one-out cross-validation correlation coefficient of r 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 ¼ 0.9871, while the correlation with the value obtained using the most used Fragment Addition Method was r 2 ¼ 0.9750. These results show the predictive capacity of the I ET for these physical properties.

Modeling the semi‐empirical electrotopological index in QSPR studies for aldehydes and ketones

“…This index has been extended to other classes of compounds, such as linear and branched ketones and aldehydes [26][27][28][29][30][31][32][33][34][35]. The values attributed to each type of carbon atom (primary, secondary, tertiary and quaternary) as vertices of the chemical graph were based on the results of the experimental gas chromatography behavior.…”

Molecular Interactions in Chromatographic Retention: A Tool for QSRR/QSPR/QSAR Studies

“…The values to be attributed to the carbon atoms, and to the functional group (Ci) for halogenated hydrocarbons, are calculated by numerical approximation based on the experimental retention index (RIExp) values and supported by theoretical considerations. The values of Ci for the carbon atoms of linear and branched halogenated aliphatic compounds can be obtained in Arruda et al (Arruda et al, 2008).…”

“…This index was initially developed to predict the chromatographic retention of linear and branched alkanes and linear alkenes, with the objective of differentiating their cis-and trans-isomers and obtaining QSRR models (Heinzen et al, 1999b). The excellent results achieved stimulated our group to extend the new topological descriptor to other classes of compounds Arruda et al, 2008;Junkes et al, 2002aJunkes et al, , 2002bJunkes et al, , 2003aJunkes et al, , 2003bJunkes et al, , 2004Junkes et al, 2005;Porto et al, 2008). The equation obtained to calculate the I ET was generated from the molecular graph and the values of the carbon atoms, and the functional groups were attributed observing the experimental chromatographic behavior and supported by theoretical considerations.…”

Development of semi‐empirical electrotopological index using the atomic charge in QSPR/QSRR models for alcohols

“…In recent years, our research group developed a topological index called the semi-empirical topological index (I ET ), to obtain QSPR/ QSAR/QSRR for different classes of organic compounds [18][19][20][21][22][23][24][25][26][27][28]. In order to obtain a molecular descriptor not directly related to the chromatographic retention indices (RI) but based on values calculated by quantum mechanics, a new semi-empirical electrotopological index (I SET ) was developed [29][30][31].…”

“…The SET i values for each atom are obtained from Equation (2) using the AM1 net atomic charges (Q i or d i ). Since Equation (2) was obtained from AM1 calculations for alkanes and alkenes [28], for consistency the net atomic charge for alcohols must be calculated using the same AM1 method (as was carried out for ketones, aldehydes and esters). We have employed the AM1 method in previous [29][30][31] and in the present calculations since it gives reliable semi-empirical bond lengths, net atomic charges and dipole moments.…”