Intercorrelation between the Wiener index, hyper-Wiener index, Harary index, hyper-Harary index, detour index and hyper-detour index is studied on three sets of branched and unbranched alkanes and cycloalkanes with up to eight carbon atoms. First set (S-39) contains all alkanes from ethane to octane (39 molecules), the second set (S-139) 139 cyclic hydrocarbons from cyclopropane to branched and unbranched polycyclic octanes and the third set (S-178) is a combination of the first two sets (178 molecules). It is found that the pairs of distance indices and the corresponding hyper-counterparts are highly intercorrelated for all three sets. The use of the distance indices of both kinds in structure-boiling point modeling was analyzed. Distance indices and hyper-distance indices do not lead to particularly good models for any of the three sets. When used as composite indices they give much-improved models. However, they are most useful when combined with such indices as the number of carbon atoms in a hydrocarbon, Hosoya Z index and/or total walk count index. The following standard errors of estimate are obtained for the best models based on the combination of descriptors: 2.1 degrees C (S-39), 4.4 degrees C (S-139) and 4.1 degrees C (S-178). They compare favorably with the related models in the literature.
Bibliographical noteFunding Information:
This paper is supported in part by the Ministry of Science and Technology of the Republic of Croatia through Grant No. 00980606 (SN and NT) and by the joint research program between the Croatian Academy of Sciences and Arts and Hungarian Academy of Sciences. Part of this work was completed during the stay of SN and NT at the Natural Resources Research Institute (NRRI), The University of Minnesota, Duluth, MN. SCB, and SN and NT (during their stay at NRRI) were supported in part by Grant Nos. F49620-94-1-0401 and F49620-96-1-0330 from the United States Air Force. We thank the reviewers for very helpful comments.