Question

assign e-z configuration​

Answer 1

Answer:

It's not necessary to include the E/Z descriptors for these compounds, because the alternative geometries would be far too strained to be stable molecules. However, there is no reason that we can't apply the rules to these compounds and assign the E/Z descriptor.

In each case, compare at the substituents on each side of the pi-bond. For the top compound, one side of the alkene has Br compared to a carbon group, and Br is higher priority. On the other side, hydrogen is lower priority than a carbon group. The higher priority groups are trans, which makes the geometrical stereochemistry E.

For the bottom compound, we must compare two carbon groups, and the alkene containing one is higher priority. On the other side, nitro is higher priority than the carbon group. Again, the higher priority groups are trans, which means that the stereochemistry is E.

compounds of interest

In general, it is unnecessary to define the E/Z stereochemistry until the ring size is 8.

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