Question

Which of the following represents the correct order of acidity in the given compounds?

• A. \( \text{FCH}_2\text{COOH}>\text{CH}_3\text{COOH}>\text{BrCH}_2\text{COOH}>\text{ClCH}_2\text{COOH} \)
• B. \( \text{BrCH}_2\text{COOH}>\text{ClCH}_2\text{COOH}>\text{FCH}_2\text{COOH}>\text{CH}_3\text{COOH} \)
• C. \( \text{FCH}_2\text{COOH}>\text{ClCH}_2\text{COOH}>\text{BrCH}_2\text{COOH}>\text{CH}_3\text{COOH} \)
• D. \( \text{CH}_3\text{COOH}>\text{BrCH}_2\text{COOH}>\text{ClCH}_2\text{COOH}>\text{FCH}_2\text{COOH} \)

Hint:

Substituents with strong electron-withdrawing effects increase the acidity of carboxylic acids by stabilizing the carboxylate ion. The more electronegative the substituent, the stronger the effect.

Answer 1

The Correct Option is C

The acidity of carboxylic acids is influenced by the electron-withdrawing (-I) effect of substituents attached to the carbon adjacent to the carboxyl group (\( \text{COOH} \)). These substituents pull electron density away from the carboxylate ion, stabilizing it and thus enhancing the acidity. Electronegativity order: \[ F>Cl>Br>H. \] Fluorine, being the most electronegative, exerts the strongest -I effect, leading to the greatest stabilization of the carboxylate ion and the highest acidity. Chlorine and bromine follow in decreasing order of electronegativity, with hydrogen exerting no such withdrawing effect. Final Answer: \[ \boxed{\text{FCH}_2\text{COOH}>\text{ClCH}_2\text{COOH}>\text{BrCH}_2\text{COOH}>\text{CH}_3\text{COOH}} \]