Q11-75E - Organic Chemistry (Mcmurry)

Question

In light of your answer to Problem 11-74, explain why one of the following isomers undergoes E2 reaction approximately 100 times as fast as the other. Which isomer is more reactive, and why?

Step-by-Step Solution

Answer

H and Cl atoms are in anti-peri planar manner

Step 1: Elimination reaction

Elimination is a chemical reaction in which several atoms whether in pairs or groups are removed from a molecule. Elimination reactions are more complex than substitution reactions for several reasons. One is the problem of regioselectivity.

Step 2: Explanation

In these two given isomers, b isomer undergoes ${\mathrm{E}}_2$ -elimination faster than an isomer because in the b isomer the two leaving groups are in Exo position in 1 and 2 carbon atoms respectively. These both are in the anti-peri planar geometry. So, their removal is easy when compared to compound a in which leaving groups are in syn position.

 

H and Cl atoms are in anti-peri planar manner