Cahn–Ingold–Prelog priority rules

Naming convention for stereoisomers of molecules

In organic chemistry, the Cahn–Ingold–Prelog (CIP) sequence rules (also the CIP priority convention; named after Robert Sidney Cahn, Christopher Kelk Ingold, and Vladimir Prelog) are a standard process to completely and unequivocally name a stereoisomer of a molecule. The purpose of the CIP system is to assign descriptors, R or S to each stereocenter and E or Z to each double bond, so that the configuration of the entire molecule can be specified uniquely by including the descriptors in its systematic name. A molecule may contain any number of stereocenters and any number of double bonds, and each usually gives rise to two possible isomers.

From Wikipedia, under CC BY-SA. More on occurri.