Molecular connectivity VII: specific treatment of heteroatoms.

The molecular connective index, chi, initially designed for hydrocarbons, has been formally extended to molecules containing heteroatoms. The sigma value of the heteroatom is modified to take account of its number of attached hydrogen atoma, sigmaiv = Zv - hi. These values were successfully tested on boiling points and molar refractions. A table of sigmav values is presented for nitrogen, oxygen, fluorine, chlorine, bromine, and iodine in various bonding situations.