Question

The decreasing order of reactivity towards dehydrohalogenation (${\mathrm{E}}_1$) reaction of the following compounds is:

• A. B > A > D > C
• B. B > D > C > A
• C. B > D > A > C
• D. D > B > C > A

Answer 1

The correct option is D

D > B > C > A

Explanation of the correct option:

The correct answer is option D:

1. The production of the carbocation is the rate-determining stage in the ${\mathrm{E}}_1$ process.
2. So the rate is determined by the stability of the generated carbocation.
3. Option D involves resonance stabilizing the newly formed cation.
4. D > B > C > A is the correct order of reactivity towards dehydrohalogenation.
5. Carbocation serves as the intermediary in the E1 reaction.
6. Rate and carbocation stability are directly proportional to each other.

Hence, option D is correct.
The decreasing order of reactivity towards dehydrohalogenation (${\mathrm{E}}_1$) reaction of the following compounds is D > B > C > A.