Question

Which of the following is not an examples of $E1CB$ reaction?

• A.
• B.
• C.
• D. All of the above

Answer 1

The correct option is B

Compound (b) does not give $E1cB$ reaction because there is no EWG in the substrate to stabilise the conjugate base.

It goes by E2 mechanism because $t-Bu{O}^{-}$ is a strong base and $-Cl$ is a better leaving group so proton abstraction and removal of leaving group occurs simultaneously.

All other compounds show $E1$cB reaction because they have EWG and poor leaving group like $-OH$.