Chemistry · JEE Advanced only

Carboxylic Acids: Preparations and Reactions (JEE Advanced)

Not in the JEE Main syllabus, but it is in JEE Advanced. Study time: about 4-5 hours (1.5 hours for preparation methods, 1.5 hours for reactions, 1-2 hours for practice problems and mechanism understanding).

Last updated: 26 October 2026

Direct answer

Carboxylic acids are organic compounds with the -COOH functional group.

Carboxylic acids are organic compounds with the -COOH functional group. This topic covers how to make them (from nitriles, Grignard reagents, ester/amide hydrolysis, and oxidation of alkylbenzenes) and what reactions they undergo (reduction, halogenation, ester formation, acid chloride formation, and amide formation).

Official syllabus

What the JEE Advanced syllabus says

“Preparation: from nitriles, Grignard reagents, hydrolysis of esters and amides; Preparation of benzoic acid from alkylbenzenes; Reactions: reduction, halogenation, formation of esters, acid chlorides and amides”

Source: JEE Advanced 2026 Information Bulletin, Annexure-I. Closest JEE Main topic: Acidic strength and factors affecting it.

JEE Main focuses mainly on acidic strength and factors affecting it, but Advanced expects you to know the actual synthesis routes and reaction mechanisms. You need to add preparation methods and named reactions that Main does not test.

Key ideas

What you must understand

Nitrile hydrolysis: R-CN + 2H₂O → R-COOH + NH₃ (acid or base catalyzed, goes through amide intermediate)
Grignard route: R-MgX + CO₂ → R-COO⁻MgX⁺, then H₃O⁺ gives R-COOH (adds one carbon)
Ester hydrolysis: acidic gives RCOOH + R'OH; basic (saponification) gives RCOO⁻ + R'OH
Benzoic acid prep: toluene or any alkylbenzene with KMnO₄/H⁺ or K₂Cr₂O₇/H⁺ oxidizes the side chain to -COOH regardless of chain length
Reduction: LiAlH₄ reduces -COOH to -CH₂OH (primary alcohol); NaBH₄ does not reduce carboxylic acids
Hell-Volhard-Zelinsky (HVZ) reaction: RCOOH + Br₂/P → α-bromo acid (works only with α-H present)

Formulas

Formulas and key facts

R-CN + H₂O (H⁺ or OH⁻) → R-CONH₂ → R-COOH
R-MgX + CO₂ → R-COOMgX → (H₃O⁺) → R-COOH
RCOOR' + H₂O (H⁺) ⇌ RCOOH + R'OH
RCOOR' + NaOH → RCOONa + R'OH (saponification, irreversible)
C₆H₅-CH₃ + KMnO₄/H⁺ → C₆H₅-COOH
RCOOH + LiAlH₃ → RCH₂OH
RCOOH + SOCl₂ → RCOCl + SO₂ + HCl
RCOOH + Br₂/P → RCHBrCOOH (HVZ reaction)

Avoid

Common mistakes

Forgetting that Grignard + CO₂ adds one carbon to the chain, so product has one more carbon than the Grignard reagent
Confusing acidic vs basic hydrolysis of esters: acidic is reversible and gives free acid, basic is irreversible and gives carboxylate salt
Thinking NaBH₄ can reduce carboxylic acids (it cannot; you need LiAlH₄)
In HVZ reaction, forgetting that it only works when α-hydrogen is present and only α-position gets halogenated

Worked example

A JEE Advanced-level example

Question. An organic compound A (C₂H₃N) on treatment with dilute H₂SO₄ gives compound B. Compound B on reaction with SOCl₂ gives compound C. Compound C on treatment with NH₃ gives compound D. Identify A, B, C, and D.

Show solution

A is C₂H₃N which is CH₃CN (acetonitrile/methyl cyanide)
A + dilute H₂SO₄ (hydrolysis): CH₃CN → CH₃COOH (acetic acid). So B = CH₃COOH
B + SOCl₂: CH₃COOH + SOCl₂ → CH₃COCl + SO₂ + HCl. So C = CH₃COCl (acetyl chloride)
C + NH₃: CH₃COCl + 2NH₃ → CH₃CONH₂ + NH₄Cl. So D = CH₃CONH₂ (acetamide)

Answer: A = CH₃CN (acetonitrile), B = CH₃COOH (acetic acid), C = CH₃COCl (acetyl chloride), D = CH₃CONH₂ (acetamide)

Solved twice independently; both solutions agree.

FAQs

Frequently asked questions

Is Carboxylic Acids: Preparations and Reactions in the JEE Main syllabus?

No. It is in the JEE Advanced 2026 syllabus only. The closest JEE Main topic is Acidic strength and factors affecting it.

How long does Carboxylic Acids: Preparations and Reactions take to prepare for JEE Advanced?

About 4-5 hours (1.5 hours for preparation methods, 1.5 hours for reactions, 1-2 hours for practice problems and mechanism understanding), if you already know the related JEE Main topic.