All acyclic hydrocarbons: formula periodic table and property overlap plots via chemical combinatorics

It is sought to extend the characterization of isomer classes by using comb inatoric techniques long used for isomer enumerations. To this end a genera l family of isomers (which is challenging to deal with even at the level of conventional enumeration) is considered, namely that of all acyclic hydroc arbons CnH2m with classical valence structures. This set of hydrocarbons is partitioned into structural-isomer classes, and these in turn are presente d in the form of a "formula periodic table" with n and m identifying rows a nd columns, respectively. Then various isomer-class-averaged characteristic s (beyond isomer enumerations) are sought to be entered into the associated positions in this periodic table. Such characteristics include heat of for mation, magnetic susceptibility and index of refraction, each of which may be estimated ain substructural "cluster expansion". These cluster-expansion -estimated property averages as well as associated standard deviations are developed by way of a generating-function chemical combinatorics for isomer s of up to n = 25 carbons and 2m = 52 hydrogens. These results then are inc orporated in property "overlap plots" to reveal overall isomer-class proper ty trends in the periodic table for this set of approximate to 10(13) struc tural isomers distributed over approximate to 360 isomer classes.