Semi-empirical topological method for the prediction of the chromatographic retention of cis- and trans-alkene isomers and alkanes

A new index is proposed for the prediction of the chromatographic retention of the cis- and trans-n-alkene isomers and alkanes. This index is based on the hypothesis that the chromatographic retention of the molecule is due t o the interaction of each carbon atom with the stationary phase, and conseq uently the index is reduced by its neighbours' steric effects. The topologi cal values are obtained by a numerical approximation considering the genera l behaviour of the chromatographic retention of the compounds. The simple l inear regressions between the chromatographic retention and the index propo sed for all branched alkanes and also isomers of the studied straight-chain C-5 and C-14 alkenes (1-ene, cis- and trans-2-, 3-, 4-, 5-, 6- and 7-enes) is very good (the correlation coefficient is r=0.9999), and the elution se quence is correct for most of them. The models have a high predictive abili ty, as established by cross-validation values (r(cv)(2)). Thus, this new me thod, different from those already existent, can be used as complementary t ool for the elucidation of the molecular structure, or prediction of the ch romatographic retention of the cis- and trans-alkene isomers and branched a lkanes. It could be extended with success, in the future, to the other type s of compounds. (C) 1999 Elsevier Science B.V. All rights reserved.