Question

The decreasing order of reactivity towards dehydrohalogenation $E_1$ reaction of the following compounds is

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

Answer 1

The correct option is D D> C > A > B

In elimination reaction of first order, reaction proceeds via carbocation formation, therefore the stability of carbocation decides the speed of $E_1$ reaction. Greater the stability of carbocation faster the reaction will be.
Stability of carbocation formed by the corresponding compound is in the order D> C > A > B and so is the dehydrohalogenation order. thus option (b) is correct.