Q9-7P b - Organic Chemistry (Mcmurry)

Question

The pk_a of acetone, CH₃COCH₃, is 19.3. Which of the following bases is strong enough to deprotonate acetone?

(b) $\mathit{N}{\mathit{a}}^{\mathbf{+}}{\mathbf{ }}^{\mathbf{-}}\mathit{C}\mathbf{\equiv }\mathit{C}\mathit{H}$$\left({\mathrm{pk}}_a{H}_2{O}_{2 }\mathrm{of} 25\right)$

Step-by-Step Solution

Answer

Answer:

Yes, strong enough to deprotonate acetone due to more pk_a then acetone.

Step 1: pk a of acetone

pk_a is a number that describes the acidity of the molecule lower the value of pk_a stronger will be acidic and easily donate a proton and the higher the value of pk_a weaker will be the acid and stronger will be the conjugate base.

Acetone has a low value of  pk_a then $N{a}^{+}{ }^{-}C\equiv CH$

Step2: pk a of N a +   - C ≡ C H

pk_a of $N{a}^{+}{ }^{-}C\equiv CH$ is more than acetone so that $N{a}^{+}{ }^{-}C\equiv CH$ is the weak acid and the strong conjugate base than acetone due to the strong conjugate base $N{a}^{+}{ }^{-}C\equiv CH$ able to deprotonate the acetone.