Introduction 

Organic Chemistry often feels like a maze for JEE aspirants — countless reactions, confusing mechanisms, and exceptions. But the truth is, most JEE Organic Chemistry questions revolve around a set of core reactions. In this blog, we’ll cover the Top 10 Organic Chemistry Reactions you must know to ace JEE Main and Advanced. Learn their concept, mechanism, and typical question patterns.

1. Aldol Condensation

Concept: Reaction between two aldehydes or ketones having α-hydrogen in the presence of dilute alkali. Product: β-Hydroxy aldehyde or β-Hydroxy ketone → (on heating) α,β-unsaturated compound. 

Example: 2 CH₃CHO → CH₃CH(OH)CH=CHCHO 

JEE Tip: Common in mechanism-based MCQs and product prediction questions.

2. Cannizzaro Reaction

Concept: Aldehydes without α-hydrogen undergo disproportionation in presence of a strong base. Product: One molecule oxidized to acid; another reduced to alcohol. Example: 2 HCHO + NaOH → HCOONa + CH₃OH 

JEE Tip: Watch out for compounds like benzaldehyde, formaldehyde, etc.

3. Kolbe’s Electrolysis

Concept: Electrolysis of sodium salt of carboxylic acid. Product: Alkane (at anode) + CO₂ (at anode) + H₂ (at cathode)

. Example: 2 CH₃COONa → C₂H₆ + 2 CO₂ + 2 Na 

JEE Tip: Useful in hydrocarbon formation questions.

4. Wurtz Reaction

Concept: Coupling of two alkyl halides in presence of sodium metal in dry ether. Product: Higher alkane. 

Example: 2 CH₃Br + 2 Na → C₂H₆ + 2 NaBr

 JEE Tip: Limited to symmetrical alkanes; unsymmetrical give mixtures.


5. Friedel–Crafts Alkylation & Acylation

Concept: Substitution reaction in aromatic compounds using AlCl₃ catalyst. Product: Alkyl or acyl substituted benzene. 

Example: C₆H₆ + CH₃Cl → C₆H₅CH₃ (Toluene) 

JEE Tip: Remember deactivation by acylation vs activation by alkylation.

6. Ozonolysis

Concept: Oxidative cleavage of alkenes/alkynes using ozone. Product: Carbonyl compounds (aldehydes or ketones).

 Example: CH₂=CH₂ + O₃ → 2 HCHO

 JEE Tip: Key reaction for structure elucidation.



7. Sandmeyer Reaction

Concept: Substitution of diazonium salt group (–N₂⁺) with Cl, Br, CN using Cu salts. Example: C₆H₅N₂⁺Cl⁻ + CuCl → C₆H₅Cl + N₂ 

JEE Tip: Focus on diazonium ion formation from aromatic amines.



8. Reimer–Tiemann Reaction

Concept: Phenol + chloroform + NaOH → o-Hydroxybenzaldehyde (salicylaldehyde).

JEE Tip: Frequently asked in name-reaction identification questions.



9. Hoffmann Bromamide Degradation

Concept: Amide + Br₂ + NaOH → Amine with one less carbon atom.

 Example: CH₃CONH₂ → CH₃NH₂ + CO₂ 

JEE Tip: Remember “loss of one carbon atom”.



10. Rosenmund Reduction

Concept: Reduction of acid chloride to aldehyde using H₂/Pd–BaSO₄.

 Example: CH₃COCl → CH₃CHO

 JEE Tip: Catalyst choice is key — prevents over-reduction.

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