Question

Which one of the following(s) is/are correct statement regarding $E2$ reaction?

• A. Polar aprotic solvent favour $E2$ reaction
• B. Strong bases are preferred
• C. Rate depends on R-X and base used
• D. Reaction goes by carbanion intermediate

Answer 1

Answer: (A), (B), (C)

Rate depends on R-X and base used

A strong Base favours E2 reaction as it readily attacks the proton.

In E2, rate of the reaction depends on the concentration of both the substrate and the base involved.

$\text{Rate of the reaction}\propto [R-X{]}^1[Base{]}^1$

Thus, a strong base favours E2 reaction as it readily attacks the proton.

Polar aprotic solvent have partial positve charge and are well-shielded by steric effects from any interaction with anions, thus, it does not solvate anions to any appreciable extent.
Since, the base remains unsolvated, it readily attacks the proton.
Thus, for E2 reaction polar aprotic solvent is favourable.