Verified Solution • 2025–26 Session moderate

QJEEM23Ch9912: JEE Main 2023 Chemistry - Class 11 JEEM23Ch9912 Solution: The descending order of acidity for the following carboxylic…

The descending order of acidity for the following carboxylic acid is-

A. CH3COOH\mathrm{CH}_{3} \mathrm{COOH}

B. F3C−COOH\mathrm{F}_{3} \mathrm{C}-\mathrm{COOH}

C. ClCH2−COOH\mathrm{ClCH}_{2}-\mathrm{COOH}

D. FCH2−COOH\mathrm{FCH}_{2}-\mathrm{COOH}

E. BrCH2−COOH\mathrm{BrCH}_{2}-\mathrm{COOH}

Choose the correct answer from the options given below:

Multiple Choice Options

  • A B > C > D > E > A
  • B D > B > A > E > C
  • C B > D > C > E > A
  • D E > D > B > A > C

Step-by-Step Verified Solution

The acidity of carboxylic acids is influenced by the electron-withdrawing ability of the groups attached to the carboxylic acid. The stronger the electron-withdrawing ability of the group, the more it stabilizes the carboxylate anion (formed after losing the acidic proton), and hence the stronger the acid.

Let's look at the groups attached to the carboxylic acid in each option:

A. CH3−\mathrm{CH}_{3}\mathrm{-} : Methyl group. It's electron-donating due to the hyperconjugation effect.

B. F3C−\mathrm{F}_{3}\mathrm{C}- : Trifluoromethyl group. Strong electron-withdrawing group due to the electronegativity of fluorine atoms and inductive effect.

C. ClCH2−\mathrm{ClCH}_{2}- : Chloromethyl group. It has some electron-withdrawing ability due to the electronegativity of the chlorine atom, but it's less than that of fluorine.

D. FCH2−\mathrm{FCH}_{2}- : Fluoromethyl group. It has electron-withdrawing ability due to the electronegativity of the fluorine atom, but less than that of the trifluoromethyl group.

E. BrCH2−\mathrm{BrCH}_{2}- : Bromomethyl group. It has some electron-withdrawing ability due to the electronegativity of the bromine atom, but it's less than that of chlorine and fluorine.

So the order of acidity will be: B > D > C > E > A

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