Question

Which one is the correct order of nucleophilic strength (pK_a) of following nucleophiles?

Options

• CH₃^– > NH₂^– > OH^– > F^–

• NH₂^– > OH^– > CH₃^– > F^–

• OH^– > NH₂^– > CH₃^– > F^–

• CH₂^– > OH^– > F^– > NH₂^–

Answer 1

CH₃^– > NH₂^– > OH^– > F^– 

Explanation:

After proton donation, any species that acts as an acid forms conjugated base. Strong acids produce weak conjugated bases, whereas weak acids produce strong conjugated bases.

If we consider the acidic strength of the given species hydrides, the order will be

\[\ce{CH4 < NH3 < H2O < HF (Acidic strength)}\]

\[\ce{CH^{-}3 > NH^{-}2 > OH- > F- (Nucleophilic strength)}\]