ABSTRACT
While trial-and-error manual methods can be employed for numbers of isomers approaching 100, such methods usually fail for higher numbers of isomers (see footnote a of Table 10).
Investigators from several countries, including the Soviet Union [56, 84,136a,b], Bulgaria [136c], other countries [136d,e], FVance [137] and Yugoslavia [7,138] have developed programs for generating isomers. A few comments are necessary for the last two types of programs. The DARC-PELCO program developed by Dubois [5d] and his coworkers lies at the basis of a documentation service (QUESTEL). This program is able to generate and display isomer structures, and is based on the concept of focal coding. An interesting idea is to display the derivation of alkane isomers as a tree and increase gradually the number of carbon atoms so that on adding a new carbon atom, many new branches are added to the derivation tree.
