Mala vas 12, SI-1000 Ljubljana, Slovenia
The susceptibility for branching, Si,j, the difference-normalised difference of data for octanes, DELTA*normi, as well as a number of additional criteria are used to judge the suitability of 13 topological indices as branching indices. The indices EAmax and J are not conform with the criterion Si,j. The other indices comply also to the criterion DELTAnormi. Due to the non-linear increase of data for n-alkanes are the most inappropriate the indices Z, W, MTI in delta1. The most susceptible for branching are Z, D, W, MTI, Sch-S, and delta1, whereas the least susceptible are deltadelta1 and ID. The same sequences of increasing branching as Tc/Pc have the indices MTI, Sch-TF, W, Xu, D, and deltadelta1, with rTc/Pc around 0.98. No one tested index has the same sequences of increasing branching as ?Hf?g and BP/Tc. The most evenly distributed ?normi data have the indices Sch-TF and D. Index D behaves similarly to W, but is not degenerated. Of BIM and BIA types of indices seem the most appropriate BIA(?) regarding RV?Hf?g, BIA(Xu) regarding RVTc/Pc and BIA(deltadelta1) regarding RVBP/Tc. BIA indices should be included into equations of the Kamlet-Taft type.
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