Topological indices based on vertex, distance, and ring: on the boiling points of paraffins and cycloalkanes.

Vertex, distance, and ring (in cyclic compounds) are three essential structure elements of a molecular graph, based on which three new topological indices VDI, OEI, and RDI are proposed. Multiple regression analysis was carried out against the boiling points of 343 hydrocarbons(160 paraffins and 183 cycloalkanes) with VDI, OEI, RDI, and N(2/3)(N is the number of carbon atoms) together, and a good QSPR model was obtained: ln(577 - Bp) = 6.729609 - 0.154107N(2/3) + 2.285632 x 10(-2)VDI - 7.921410 x 10(-3)OEI - 1.821962 x 10(-2)RDI (F = 6455.09, r = 0.9935, rms = 6.44 degrees C, n = 343).