Q34. - Organic Chemistry

Question

Question: What hydrogen atoms in each compound have a pk_a ≤ 25?

Step-by-Step Solution

Answer

Answer

 

The hydrogen atoms in each compound have a pK_a ≤ 25, as shown below:

Step 1: Criteria for acidity

A compound is considered to be highly acidic when the intermediate structure formed after the proton abstraction is stabilized by resonance or -I effect of the adjacent group (generally an electronegative element).

Step 2: Stability of the negative charge

The negative charge formed after the proton abstraction undergoes extensive resonance along with the exertion of -I effect of the adjacent group. More the stability of the conjugate base formed, more will be its acidity.

                    Representation of the resonating structures

 

 The -I effect is shown by the carbonyl group.

                        Representation of the resonating structures

 

The -I effect is shown by the carbonyl group.

Representation of the resonating structures

 

The -I effect is shown by the phenyl group.

 

Based on the explanations, the hydrogen atoms in each compound have a pK_a ≤ 25, as shown below:

      The acidic hydrogen a.

     The acidic hydrogen b.

    The acidic hydrogen c.