The octane number (ON, MON and PON) for the molecular structures of 18 octane isomers have been correlated using the quantitative structure-property relationship (QSPR) method, with topological index SD. For single parameter correlation the index SD shows poor results (RON, r = 0.406; MON, r =0.490; PON, r =0.448), whereas for two-parameter correlation almost any combination among the above D_C was found to give relatively high r value. The best correlation coefficients are as follows: for RON, r = 0.993; MON, r =0.968; PON, r =0.985.
For RON, the best model obtained by our regression analysis is

    \[RON = -227.218 + 7.63 * SD - 37.111 * D_C {\rm with } r = 0.993,\, s = 4.8,\, F = 534.\]


Additional Information


 Berinde, Zoiţa-Mărioara, Butean, Claudia, Dippong, Thomas