Question

Which of the following is(are) true statement regarding free redical bromination of an alkane?

• A. It occur repidly but very less selectively
• B. It occur with difficulty as compared to chlorination but a highly selective reaction
• C. Transition state fot H abstraction in propagation step is closer to reactant than product in terms of potential energy
• D. Transition state fot H abstraction in propagation step is closer to product than reactant in terms of potential energy

Answer 1

Answer: (B), (D)

It occur with difficulty as compared to chlorination but a highly selective reaction
Transition state fot H abstraction in propagation step is closer to product than reactant in terms of potential energy

b) Bromination is less reactive but highly selective
d) Bromination product is less stable, comes closer to transition state in terms of potential energy.

The bromination process requires $AlB{r}_3$ as a catalyst. Whereas in chlorination there is no need of such catalyst, Also the bromination forms only one product unlike chlorination where the mixture of a number of product is obtained, So, bromination is very selective.

The bromination product are not as stable as chorination product as their energies are very high.