Fast Generation of an Alkane-Series Dictionary Ordered by Side-Chain Complexity

Selecting the main chain of an alkane as the path that yields the least complex side chains without the maximum-length constraint leads to an efficient generating algorithm representable as nested binary trees. The largest side chain required to specify an N-carbon alkane becomes (N-1)/3. This allows 3.8 million C1-C22 alkanes to be coded for name translation in dictionary order, using an alphabet of 33 C1-C6 alkyl groups also ranked by complexity. The generating process produces reversible isomer codes already in canonical order, making the computation rate in isomers per second inverse linear with N and much faster than reported rates for other structure generators.