Determination of E and Z isomers
- The priority of a groups depends upopn the atomic number of
the atom attached to the double bond. The higher the atomic
number, the higher the priority of the group is.
- If two atoms with the same priority are bound to the carbon
atom of the double bond, a search is made along each group, moving
away from the double bond until a difference is found, and
priority is assinged on the basis of that difference.
- The double bond is assigned a Z (for zusammen,
German for together) configuration when the two groups
with the higher priority at each end of the doube bond are on the
same side of the molecule. If the two groups of higher priority
are on opposite sides of the double bond, the molecule is given an
E (for entgegen, German for opposite)