Gas chromatographic retention and molecular structure, further imbrication of isomer lines in plots of alkenes, and assignment of cis and trans configuration

A detailed relationship between the structure of the alkenes, C4-C7 inclusive, and gas chromatographic data is described. For this purpose, relative retentions have been brought into logarithmic form and diagrams have been constructed in which a point represents the retention indices of one compound on two stationary phases. It is shown that, in these diagrams, alkenes having certain structural elements in common can be joined by straight lines, that these lines are parallel, and that the order of the lines is also related to the number of structural elements. The structural elements chosen are primary, secondary, tertiary, and quaternary carbon atoms, the cis and trans configuration, and, to some extent, the position of the double bond. An application to the assignment of cis and trans configuration in the case of certain heptenes is discussed. This description of retention data should be useful for purposes of identification.