Question

For each of the following compounds, draw the possible geometric isomers and name each isomer:

a. 2-methyl-2,4-hexadiene b. 1,5-heptadiene c. 1,4-pentadiene d. 3-methyl-2,4-hexadiene

Short answer

Here we have to draw possible geometric isomer for each of the following compound:

(a)

(b)

(c)

(d)

3-methyl-2,4-hexadiene

Step-by-step solution

What is the geometrical isomer

The compounds which have the same molecular formula but different structure. The functional groups are rotated in different orientation in three dimensional space. These are also called cis- trans isomers. Cis-trans name is used for when hydrogen atom is bonded with sp² carbon atom.

But in alkene the hydrogen atom is not bonded with the sp²hybridized carbon then in this it is renamed as E and Z configuration.

Steps to draw E and Z isomers

1. Assign the priority order to the groups on the basis of atomic number. Higher atomic numbers get the highest priority.

2. If higher priority groups are on the same side then it will be Z isomer.

3. If higher priority groups are on the different sides then it will be E isomer.

How to give priority 

1. Assign the priority order to the groups on the basis of atomic number. Higher atomic numbers get the highest priority.

2. Double bond is considered as carbon is attached to 2 carbons.

3. Triple bond is considered as carbon is attached to 3 carbons.