Q.24 - Organic Chemistry

Question

Rank the alkenes shown in the ball-and-stick models (A–C) in order of increasing stability.

Step-by-Step Solution

Answer

The alkenes are ranked based on stability are shown below:

Stability based on substitution

With more number of substitutions, there will be more stability. This is because, with the increase of substitution of the alkyl groups, more will be the +I effect shown by the alkyl groups to the double-bonded carbon. 

 

Due to this, the stability increases. This is why structures A and C are more stable than B.

Representation of the number of substituents present across the alkene

Stability based on steric repulsion

Cis alkenes suffer from steric interactions since both the higher priority groups lie in the same orientation. But in trans alkenes, steric repulsion is not there due to the higher priority groups lying in the opposite direction. 

This is why structure A is more stable than C.

Representation of steric interactions

Based on the explanations, the alkenes are ranked based on stability are shown below:

Order of increasing stability