Question

Which of the following has the fastest rate for $E_{1}cB$ reaction?

• A.
• B.
• C.
• D. None of the above

Answer 1

The correct option is C

For an E1cB reaction, a electron withdrawing group must be present at the $\beta$ - position. Also, Poor leaving group $(E.g.F^{-},O{H}^{-})$, etc. prefers $E_{1}cB$ reaction.
Among the given options, $F^{-}$ has the poor leaving capability
Hence it shows better $E_{1}cB$ reaction.