Application of the semi-empirical topological index in quantitative structure-chromatographic retention relationship (QSRR) studies of aliphatic ketones and aldehydes on stationary phases of different polarity

Abstract

O índice semi-empírico topológico, desenvolvido previamente por Heinzen e Yunes, foi aplicado para predizer a retenção cromatográfica de cetonas e aldeídos alifáticos, em fases estacionárias de diferentes polaridades (HP-1, HP-50, DB-210 e Innowax). Foram estabelecidas regressões lineares simples entre os índices de retenção experimentais e os índices semi-empíricos topológicos (RI Exp = a + bI ET ) para cada fase estacionária separadamente, sendo que os parâmetros estatísticos obtidos foram de qualidade satisfatória. A polaridade das fases estacionárias indicada pela polaridade de McReynolds (P R ), encontra-se refletida nos coeficientes das equações (a e b) obtidos para HP-1, HP-50, DB-210 e Innowax, os quais aumentam linearmente a medida que a polaridade também aumenta (intercepto). As análises estatísticas indicaram que os modelos de correlação quantitativa estrutura-retenção cromatográfica (QSRR) obtidos em fases estacionárias de baixa a média polaridade (HP-1 e HP-50) têm maior estabilidade e habilidade de predição do que os obtidos em fases estacionárias polares (DB-210 e Innowax). Sendo assim, pode-se concluir que, em fases estacionárias consideradas de baixa a média polaridade, o método semi-empírico topológico empregando somente um descritor obteve melhores resultados do que métodos que utilizaram descritores múltiplos.The semi-empirical topological index, previously developed by Heinzen and Yunes, has been applied to predict the chromatographic retention of aliphatic ketones and aldehydes on stationary phases of different polarities (HP-1, HP-50, DB-210 and Innowax). Simple linear regressions between the retention indices and the semi-empirical topological indices (RI = a + bI ET ) were established for each stationary phase separately, showing satisfactory statistical parameters. The polarity of the stationary phases, indicated by McReynolds polarity (P R ), is reflected in the coefficients of the equations (a and b) obtained for HP-1, HP-50 and DB-210, which linearly vary as the polarity of the stationary phase increases (intercept). Statistical analyses showed that the quantitative structurechromatographic retention relationship (QSRR) models obtained on stationary phases of low-tomedium polarity (HP-1 and HP-50) have higher stability and predictive ability than those on polar stationary phases (DB-210 and Innowax). Thus, it can be concluded that the semi-empirical topological method, using only one descriptor, yielded better results on low-to-medium polarity stationary phases than methods that used multiple descriptors.

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

“…These results are similar to those obtained for alkenes, methyl-branched alkanes, esters, aldehydes, ketones, and alcohols in previous studies [14][15][16]20] and can be attributed to the steric hindrance of the aliphatic side-chain on the functional group, significantly reducing the contribution of the heteroatom to chromatographic retention. A similar behavior was observed for dihalogenated compounds with two chloride atoms directly attached to a secondary carbon atom.…”

“…The calculation of the I ET values for alkanes, alkenes, esters, aldehydes, ketones, and alcohols, linear and branched, has been described in our earlier papers [13][14][15][16]19,20].…”

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

“…(vi) One of the fundamental factors taken into consideration for the development of this topological index was the importance of the steric and other mutual intramolecular interactions between the functional group and nearby atoms. Therefore, for branched molecules, different values were attributed to carbon atoms in the , , and  position with respect to the functional groups compared to those previously attributed to alkanes (Heinzen et al, 1999b) as described in the literature Junkes et al, 2003bJunkes et al, , 2004.…”

“…The values of C i for the carbon atoms and the values attributed to the functional groups of esters, aldehydes, ketones and alcohols are listed in Table 1 of Junkes et al (Junkes et al, 2004,).…”

“…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.…”