Question

The least acidic compound, among the following is 

• A. D
• B. A
• C. B
• D. C

Hint:

Acidity depends on the stability of the conjugate base. Consider the hybridization of the carbon atom from which the proton is removed and the possibility of resonance stabilization.

Answer 1

The Correct Option is A

To determine the least acidic compound among the options, we need to analyze the structures provided.

1. Acidity in organic compounds is often due to the presence of groups that can donate a hydrogen ion or stabilize the negative charge that forms after donation. Common acidic functional groups include carboxylic acids, phenols, and sulfonic acids.
2. Let's analyze each compound:
   • Compound A: Contains a phenolic -OH group. Phenols are weak acids.
   • Compound B: Contains a sulfonic acid group (-SO₃H), which is a strong acid.
   • Compound C: Contains a carboxylic acid group (-COOH), which is more acidic than phenols but less acidic than sulfonic acids.
   • Compound D: This compound is an ester and does not possess acidic hydrogen atoms like the others. Esters are generally considered neutral in terms of acidity in aqueous solutions.
3. Since esters like the one in Compound D do not release hydrogen ions readily in water, they are not considered acidic under typical conditions.
4. Therefore, the least acidic compound among the options is Compound D.

Conclusion: Compound D is the least acidic compound because it is an ester, which lacks readily ionizable hydrogen that characterizes acidic compounds.