Nomenclature of cycloHexane Bonds

Abstract

IT was shown originally by X-ray and electron diffraction, and has been confirmed by other physical and by chemical means, that the most stable and permanent form of the cyclohexane ring is that particular strainless form which is sometimes likened to a chair or a staircase. Geometrically, its chief feature is a six-fold alternating axis of symmetry. Its twelve extracyclic bonds fall into two classes¹: six lie parallel to the axis, while six extend radially outward at angles of ± 109.5° to the axis. The stereochemical properties of substituents bound by these two classes of bond are so different that a need has been felt for verbal and symbolic means of distinguishing the classes.