Question

The correct order for the acidic character of the following carboxylic acids is

• A. IV $>$ I $>$ II $>$ III $>$ V
• B. V $>$ II $>$ IIII $>$ I $>$ IV
• C. V $>$ II $>$ IV $>$ III $>$ I
• D. V $>$ II $>$ IV $>$ I $>$ III

Answer 1

Answer: (D)

$V$ is most stable because its anion is stabilized to a greater extent through $H$ - bonding with $H$ atom of $OH$ present on both ortho-positions ; followed by II in which one $OH$ group is present. Compound IV comes next to II because here $-OC{H}_3$ group is present in ortho position which although is not capable of forming $H$-bonding yet more acidic than $p-HO{C}_6{H}_{4}COOH$ (III) due to ortho effect. Compound III is less acidic than benzoic acid because of electron-releasing group in the para position. Thus