Question

Question : Which of the following E, Z designations are correct, and which are incorrect ?

Short answer

Answer

1. Correct
2. Correct
3. Incorrect
4. Correct
5. The molecule cannot be assigned E or Z configuration.
6. Correct

Step-by-step solution

Definition of E and Z configuration

When the substituents with highest priority on both carbon atom of alkene are present adjacent to each other, then the alkene has as Z configuration.

Similarly, when the highest priority groups are trans (opposite) to each other. Then the alkene has E configuration.

Numbers 1 and 2 define the priority in the image given below :

Configuration of (a)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene.

As similar priority groups present on the same side. So, the configuration is Z configuration. Hence, the assigned configuration is correct.

Configuraion of (b)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene

As similar priority groups present on the same side. So, the configuration is E configuration. Hence, the assigned correction is correct.

Configuration of (c)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene.

As similar priority groups present on the same side. So, the configuration is E configuration. Hence, the given configuration is incorrect.

Configuration of (d)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene

As similar priority groups present on the same side. So, the configuration is E configuration. Hence the configuration is correct.

Configuration of (e)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene

In this compound, on one side of carbon similar groups are present. So priority cannot be assigned for this molecule. Hence, the given configuration is incorrect.

Configuration of (f)

Assign the priority on the basis of the atomic numbers of the different atoms which are attached to alkene.

As similar priority groups present on the same side. So, the configuration is E configuration. Hence, the given configuration is correct.