Question

Which of the following statements regarding mechanisms of elimination reaction is wrong?

• A. The E1 mechanism does not require a base.
• B. The E2 mechanism generally occurs under highly basic conditions.
• C. The E1cB mechanism is usually unimolecular via conjugate base in the rate-determining step.
• D. None of the above

Answer 1

The correct option is A The E1 mechanism does not require a base.

$E1$ reaction is a two step process.
In step 1, leaving group leaves and form a carbocation.
In step 2, the base will attack the proton and proton abstraction takes place. Thus, base is required in $E1$ reaction and hence option (a) is wrong.

In $E2$ reaction, two groups/atoms depart simultaneously from adjacent carbons with a proton being abstracted by a base thus it occur in highly basic condition.

In $E1cB$, the reaction proceeds through the conjugate base of the starting material, thus, they called as unimolecular elimination via conjugate base.