chapter  21
24 Pages

Stereochemical Terminology

WithMichael Edenborough

In order to distinguish between the two possibilities, further information must be included in the name of the compound, that is stereochemical terminology is needed. They are: S8 and Sn. Structural isomers may be divided into five sub-types: skeletal, positional, functional, and tautomeric and meta. On a long straight-chained molecule that has a functional group; it is possible for this group to be placed at a number of different positions on the carbon chain. This is referred to as positional isomerism. The two most frequent examples of this type are the enol/keto and the aci/nitro tautomeric systems. The idea of enantiometric molecules may be extended from an atomic centre to a face of a trigonal molecule, by an extension of the Cahn-Ingold-Prelog system. Compounds in which rotation is restricted can exhibit geometric isomerism. A reaction in which only one set of stereoisomers is formed exclusively or predominantly is termed a stereoselective synthesis.