Molecular Modeling in Chromatoscopy as a New Tool in the Structure Elucidation of Novel Isomers by GC/MS

Abstract

The importance of gas–solid chromatography on graphitized thermal carbon black (GTCB) as a source of additional data for the positive structural elucidation of novel isomers by gas chromatography–mass spectrometry is discussed. The retention parameters of isomers being investigated were calculated by Kiselev's method (chromatoscopy) to predict the order of their separation on a column packed with GTCB. To extend the possibilities of this method and to improve the accuracy of a prediction of retention parameters, the molecular mechanics was used for the optimization of hypothetical molecular models of isomers required for these calculations. As a test mixture 11 isomers of perhydroanthracene and perhydrophenanthrene were consedered. The predicted elution order from the column packed with GTCB of these isomers, calculated on the basis of molecular models optimized by molecular mechanics appeared to be close to the experiment, whereas the result obtained by a conventional approach appeared to fail. Molecular modeling in chromatoscopy was used for the structural elucidation of novel isomers of perhydroxanthene (PHX) and perhydro-4-thia-s-indacene (PHTI), which were found by GC–MS in reaction mixtures. The evidence for this assignment-based on the obtained GC and MS data, is discussed.