Chemical Meaning of Octane Number Analyzed by Topological Indices

Abstract

Correlation of the octane number (ON) of heptane and octane isomers with various topological indices, Z, w, p, and B, was studied. One of the best results of regression analysis is: ON=76.389+8.179(0.3B+1.1p-0.6Z) with r=0.982 for octane isomers. From these analyses one can concluded that in order for a gasoline isomer is to have high ON, or to be burnt without knocking, it should be highly branched (small Z or low boiling point), its statistically averaged shape should be spherical (large B), and it should have a compact structure (large p or high liquid density). From these results several candidates of nonane isomers whose ON is expected to be higher than 100 are suggested.