## ABSTRACT

An alternative use of the cis and trans notation to indicate relative stereochemistry is the E-Z notation. A set of rules known as the Cahn-Ingold-Prelog rules gives each substituent on a double bond an assigned priority. In the example shown in Figure 4.3, as an extension of the use of the cis and trans notation to indicate relative stereochemistry, the E-Z notation is generally accepted to describe the absolute con-guration of the double bonds. The higher priority is given to the methyl group. Thus, when the two groups of higher priority are on opposite sides of the double bond, the bond is assigned the conguration E. Conversely, if the two groups are on the same side of the double bond, the bond is assigned the conguration Z (Figure 4.3).