In stereochemistry, the Klyne–Prelog system (named for William Klyne and Vladimir Prelog) for describing conformations about a single bond offers a more systematic means to unambiguously name complex structures, where the torsional or dihedral angles are not found to occur in 60° increments.
[1] Klyne notation views the placement of the substituent on the front atom as being in regions of space called anti/syn and clinal/periplanar relative to a reference group on the rear atom.
Clinal substituents are found within 30° of either side of a dihedral angle of 60° (from 30° to 90°), 120° (90°–150°), 240° (210°–270°), or 300° (270°–330°).
Juxtaposing the designations produces the following terms for the conformers of butane (see Alkane stereochemistry for an explanation of conformation nomenclature): gauche butane is syn-clinal (+sc or −sc, depending on the enantiomer), anti butane is anti-periplanar, and eclipsed butane is syn-periplanar.
[2] This stereochemistry article is a stub.