plz,explain in simple way E and Z notation for geometrical isomers

Asked by Babita Devi | 8th Oct, 2010, 07:29: PM

Expert Answer:

How the E-Z system works

We'll use the last two compounds as an example to explain how the system works.

You look at what is attached to each end of the double bond in turn, and give the two groups a "priority" according to a set of rules which we'll explore in a minute.

In the example above, at the left-hand end of the bond, it turns out that bromine has a higher priority than fluorine. And on the right-hand end, it turns out that chlorine has a higher priority than hydrogen.

If the two groups with the higher priorities are on the same side of the double bond, that is described as the (Z)- isomer. So you would write it as (Z)-name of compound. The symbol Z comes from a German word (zusammen) which means together.

f the two groups with the higher priorities are on opposite sides of the double bond, then this is the (E)- isomer. E comes from the German entgegen which means opposite.

So the two isomers are:

Summary

  • (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.

Answered by  | 8th Oct, 2010, 07:55: PM

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