See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analyzing Acidic Strength of Carboxylic Acids **Key Principle:** Acidic strength of $-COOH$ depends on electron-withdrawing groups (EWG) attached to the benzene ring. EWGs stabilize the conjugate base ($-COO^-$), making the acid stronger. ## Analysis of Each Compound: **(1) 2,6-Dinitrobenzoic acid:** Two $-NO_2$ groups (strong EWGs) in ortho positions flanking the carboxylic acid. Extremely electron-withdrawing → **highest acidity** **(2) 4-Nitrobenzoic acid:** One $-NO_2$ group (strong EWG) in para position. Moderately electron-withdrawing → **strong acidity** **(3) 2,6-Dihydroxybenzoic acid:** Two $-OH$ groups (weak EWGs, actually electron-donating through resonance) in ortho positions. These destabilize the conjugate base → **weakest acidity** (weaker than even compound 4) **(4) 4-Nitrobenzoic acid with $-OH$:** Mixed effects—one strong EWG ($-NO_2$) and one weak/donating group ($-OH$) in ortho positions. Net electron-withdrawing effect is moderate → **intermediate acidity** ## Order of Increasing Acidity: $$3 < 2 < 4 < 1$$ Rearranged: $3 > 2 > 1 > 4$ ✓ **Answer: (a) $3 > 2 > 1 > 4$**