The relation between molecular connectivity and gas chromatographic retention data.

The recently developed topological index, molecular connectivity (chi), has been correlated using multiple regression analysis with gas chromatographic retention time (Rt) for various series of compounds. For saturated and unsaturated aliphatic hydrocarbons, and aliphatic aldehydes, good correlation with log Rt was achieved by one-parameter linear equations in terms of the first-order conncectivity index. (1chi). The equation for aliphatic alcohols required an additional parameter, the valence connectivity (vchi) for satisfactory correlation. One-parameter equations using 1chi also good correlation with log Rt for three series of drug molecules, amphetamines, barbiturates and phenothiazines. In all cases the equations generated gave good agreement between calculated and observed log Rt values.