Question

Arrange the following in the order of their ability as leaving group.

${{CH}_{3}COO}^{-},{CH}_3{{SO}_3}^{-},{CF}_3{{SO}_3}^{-}$

• A. ${{CH}_{3}COO}^{-}<{CH}_3{{SO}_3}^{-}<{CF}_3{{SO}_3}^{-}$
• B. ${{CH}_{3}COO}^{-}>{CH}_3{{SO}_3}^{-}>{CF}_3{{SO}_3}^{-}$
• C. ${{CH}_{3}COO}^{-}>{CH}_3{{SO}_3}^{-}<{CF}_3{{SO}_3}^{-}$
• D. ${{CH}_{3}COO}^{-}<{CH}_3{{SO}_3}^{-}>{CF}_3{{SO}_3}^{-}$

Answer 1

The correct option is A ${{CH}_{3}COO}^{-}<{CH}_3{{SO}_3}^{-}<{CF}_3{{SO}_3}^{-}$

The increasing order of their ability as leaving group is ${{CH}_{3}COO}^{-}<{CH}_3{{SO}_3}^{-}<{CF}_3{{SO}_3}^{-}$.
The ability of acetate ion as leaving group is minimum as the extent of resonance stabilization of the negative charge is minimum.
When trifluoromethyl group is present, the leaving group ability is maximum due to electron withdrawing nature.