Question

The order of decreasing nucleophilicity is

• A. $H_{2}O>O{H}^{-}>C{H}_{3}CO{O}^{-}>C{H}_3{O}^{-}$
• B. $C{H}_{3}CO{O}^{-}>C{H}_3{O}^{-}>H{O}^{-}>H_{2}O$
• C. $H{O}^{-}>C{H}_3{O}^{-}>C{H}_{3}CO{O}^{-}>H_{2}O$
• D. $C{H}_3{O}^{-}>O{H}^{-}>C{H}_{3}CO{O}^{-}>H_{2}O$

Answer 1

The correct option is D $C{H}_3{O}^{-}>O{H}^{-}>C{H}_{3}CO{O}^{-}>H_{2}O$

1. Due to the presence of -ve charge $C{H}_3{O}^{-}$, $O{H}^{-},C{H}_{3}CO{O}^{-}$ , are more nucleophilic than $H_{2}O$. Further due to + I effect of the $C{H}_3$ group, $C{H}_3{O}^{-}$ is more nucleophilic than $O{H}^{-}$.

2. $C{H}_{3}CO{O}^{-}$ has the -ve charge on oxygen stabilized by resonance and therefore its nucloephilicity is less than those of $C{H}_3{O}^{-}$ and $O{H}^{-}$.