Q.42 - Organic Chemistry

Question

In the dehydrohalogenation of bromocyclodecane, the major product is cis-cyclodecene rather than trans-cyclodecene. Offer an explanation.

Step-by-Step Solution

Answer

The major product is cis-cyclodecene because it suffers from less angular strain as compared to its trans counterpart.

Identification of β hydrogens

Bromocyclodecane has two different types of $\mathbf{\text{β}}$ hydrogens, and as a result, two different forms of products are obtained, which are considered stereoisomers.

Stability based on orientations

In the case of the ring system, cis-alkene is considered to be more stable than its trans counterpart since it suffers from less angular strain. Since they suffer from less angular strain, they have lower energy and hence more stabler than trans.

 

So the major product formed is cis-cyclodecene.

Representation of stereoisomers