Question

The order of decreasing nucleophilicity of the following is:

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

Answer 1

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

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

Water is least nucleophilic as oxygen atom does not has any negative charge.

In acetate ion, the negative charge is delocalized in the carboxylate group. Hence, acetate ion is less nucleophilic than hydroxide ion and methoxide ion.

Methoxide ion has maximum nucleophilicity due to +I (electron donating) effect of methyl group which increases electron density on oxygen.