| Abstract: | The numbering of carbon atoms in organic molecules is called chain numbering. It is suggested that bonds be classified as chain bonds (between atoms with consecutive indices) and nonchain bonds. Among atoms we distinguish the first atom (No. 1) and the last atom (having the largest index) as well as initial and final atoms (starting and finishing unbranched sections of atomic chains). Also, internal numbering of elements within these classes is proposed. For condensed cyclic hydrocarbons, formulas for deriving the number of cycles are given, and a linear-chain encoding system is worked out; in this system, nonchain bonds are assigned the indices of their atoms. Rules for unique numbering (canonical chain numbering) are developed; they involve maximization of the indices of the initial atoms and nonchain bonds. The linear-chain encoding of cyclic hydrocarbon structures ensures unification and systematization of their names. Tambov State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 4, pp. 731–736, July–August, 1995. Translated by L. Smolina |
