Quantitative structure-gas chromatographic retention index relationship of long-chain esters: The case of Scandix pecten-veneris L. essential-oil constituents

Abstract

Motivated by a recent identification of two homologous series of branched butanoates and pentanoates in S. pecten-veneris essential oil, with an apparently regular change of their retention index (RI) values, we decided to examine the generality of such structure-chromatographic property relationship. Based on the experimentally obtained retention data (RI values of in total 20 compounds) of hexyl, decyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, heneicosyl and tricosyl isobutanoates and 3-methylbutanoates and selected 2-methylbutanoates, a model was built up that correlates the total number of carbon atoms, Wiener (WI), Balaban (BI) and molecular topological (MTI) indices of the mentioned esters and their RI data (RI = 240.5 + 91.2 x C + 2.94 x WI + 4.6 x 10-5 x BI - 0.381 x MTI). The obtained equation represents a new and simple tool for the prediction of gas chromatographic (retention indices) data for esters of straight long-chain fatty alcohols and branched short aliphatic acids.