In structural representation of molecule the prefixes Z and E stands for ---------
Answers
E comes from the German entgegen which means opposite. (E)- : the higher priority groups are on opposite sides of the double bond. (Z)- : the higher priority groups are on the same side of the double bond.
In structural representation of molecule E stands for the compound in which the same functional group is present on the opposite side, Z stands for the compound in which the same functional group is present on the same side.
E and Z respectively are used extensively in organic chemistry to represent the position of the function groups in organic compounds. E and Z both are derived from the Greek words E comes from Entagen meaning enemy. Which means in an organic compound the same compound are present on the opposite sides.
Z comes from the German word Zusammen which means together(friend). The same functional groups are present on the same side of the organic compound.
The organic compounds need not contain two same functional groups. For example, if in a compound all the four functional groups are different then it won't that they won't exhibit isomerism that is whether it is E or Z. If all the functional groups are different then isomerism can be obtained on the basis of priority. Priority may be based on the atomic number Or molecular weight of the functional group. The group having highest atomic number Or more molecular weight is given more priority than the other with less atomic number Or molecular weight .
This E or Z isomerism is observed only in the symmetrical organic compounds. When competing the stability of E and Z states theE state is more stable than the Z state. The reason is the steric effect. The reason is that when two large groups are present on the same side which probably means Z configuration the repulsive force on each of then by the other group is much larger. That is the reason why E configuration is always stable than the Z configuration.
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