JEE Chemistry: Complete Named Reactions Cheat Sheet for Mains and Advanced

Why Named Reactions Are High-Yield JEE Marks

In JEE Mains, Organic Chemistry accounts for roughly 30–35% of the Chemistry section. Named reactions — Aldol condensation, Cannizzaro, Sandmeyer, Wolff-Kishner, and the rest — appear in virtually every paper. They're predictable, finite in number, and reward students who know them cold.

This cheat sheet covers the 35 most frequently tested named reactions. For each one, I've noted the key detail that NTA loves to test — because most wrong answers on named reaction questions come from one specific confusion per reaction, not from not knowing the reaction at all.

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Nucleophilic Addition & Related

1. Aldol Condensation

Reagent: Dilute NaOH or KOH Substrate: Aldehydes/ketones with α-hydrogen Product: β-hydroxy carbonyl compound → dehydration gives α,β-unsaturated carbonyl NTA trick: Asks whether the product undergoes dehydration (only if heated/in concentrated base). Also tests cross-aldol vs self-aldol.

2. Cannizzaro Reaction

Reagent: Concentrated NaOH Substrate: Aldehydes WITHOUT α-hydrogen (HCHO, benzaldehyde, etc.) Product: One molecule oxidised to carboxylate + one reduced to alcohol (disproportionation) NTA trick: Asks about substrates — HCHO and benzaldehyde YES; acetaldehyde NO (has α-H).

3. Clemmensen Reduction

Reagent: Zn-Hg amalgam + conc. HCl Converts: C=O (ketone/aldehyde) → CH₂ Conditions: Acidic NTA trick: Compared to Wolff-Kishner (below). Clemmensen = acidic; Wolff-Kishner = basic.

4. Wolff-Kishner Reduction

Reagent: NH₂-NH₂ (hydrazine) + KOH in ethylene glycol Converts: C=O → CH₂ Conditions: Basic NTA trick: Same transformation as Clemmensen but opposite conditions. NTA often asks "which reaction is suitable for an acid-sensitive compound?" → Wolff-Kishner.

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Substitution Reactions (Aromatic)

5. Sandmeyer Reaction

Reagent: CuCl/HCl or CuBr/HBr Converts: Diazonium salt → aryl halide (Cl or Br) NTA trick: Iodo and fluoro substitution do NOT use Sandmeyer (use KI for iodo; Balz-Schiemann for fluoro).

6. Balz-Schiemann Reaction

Reagent: HBF₄ (fluoroboric acid) Converts: Diazonium salt → aryl fluoride NTA trick: The only named route from diazonium to fluorobenzene.

7. Gattermann Reaction

Reagent: Cu powder + HCl or HBr (no CuCl/CuBr) Converts: Diazonium → aryl halide Note: Similar to Sandmeyer but uses Cu powder instead of CuX salt. Often appears as a "which is different" question.

8. Gattermann-Koch Reaction

Reagent: CO + HCl + anhydrous AlCl₃ + CuCl Converts: Benzene → benzaldehyde (formylation) NTA trick: Different from Gattermann reaction — don't confuse the two.

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Oxidation Reactions

9. Baeyer-Villiger Oxidation

Reagent: Peroxy acid (mCPBA, peracetic acid) Converts: Ketone → ester (oxygen insertion) NTA trick: Migratory aptitude order: tertiary > secondary > aryl > primary > methyl. Tested frequently.

10. Etard Reaction

Reagent: CrO₂Cl₂ (chromyl chloride) Converts: Toluene (methyl group on benzene) → benzaldehyde NTA trick: Selective oxidation — stops at aldehyde, not carboxylic acid.

11. Stephen Reduction

Reagent: SnCl₂ + HCl Converts: Nitrile (RCN) → aldehyde (RCHO) NTA trick: Gives aldehyde, NOT primary amine (that's catalytic hydrogenation of nitrile).

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Reduction Reactions

12. Birch Reduction

Reagent: Na/Li in liquid NH₃ + alcohol Converts: Aromatic ring → 1,4-cyclohexadiene NTA trick: Electron-donating groups on ring → double bonds avoid substituted positions. EDG: unsubstituted positions get reduced. EWG: substituted positions get reduced.

13. Rosenmund Reduction

Reagent: H₂ + Pd/BaSO₄ (poisoned catalyst) Converts: Acid chloride (RCOCl) → aldehyde (RCHO) NTA trick: Poisoned catalyst prevents over-reduction to alcohol.

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Coupling and Condensation

14. Claisen Condensation

Reagent: Sodium ethoxide (strong base) Substrate: Esters with α-hydrogen Product: β-ketoester NTA trick: Cross-Claisen — only possible when one ester has no α-H (e.g., ethyl benzoate).

15. Perkin Reaction

Reagent: Acid anhydride + sodium salt of the same acid Converts: Aromatic aldehyde + anhydride → α,β-unsaturated acid NTA trick: Tested with benzaldehyde + acetic anhydride → cinnamic acid.

16. Knoevenagel Condensation

Reagent: Amine base (piperidine/pyridine) Substrate: Aldehyde + active methylene compound (malonic acid, etc.) NTA trick: Distinguish from Aldol — Knoevenagel uses amine catalyst, not hydroxide.

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Rearrangements

17. Beckmann Rearrangement

Reagent: H₂SO₄ or PCl₅ Converts: Oxime → amide (ring expansion for cyclic ketones) NTA trick: Anti group migrates (the group anti to the OH migrates to nitrogen).

18. Fries Rearrangement

Reagent: AlCl₃ Converts: Aryl ester → hydroxy ketone (ortho or para) NTA trick: Low temperature favours para product; high temperature favours ortho product.

19. Pinacol-Pinacolone Rearrangement

Reagent: Dilute H₂SO₄ (acid) Converts: Pinacol (vic-diol) → pinacolone (ketone) Mechanism: 1,2-methyl shift after protonation and loss of OH.

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Miscellaneous High-Frequency Reactions

20. Reimer-Tiemann Reaction

Reagent: CHCl₃ + NaOH Converts: Phenol → salicylaldehyde (ortho-hydroxybenzaldehyde) NTA trick: Formylation of phenol; dichlorocarbene intermediate.

21. Kolbe's Reaction

Reagent: CO₂ + NaOH (pressure) Converts: Sodium phenoxide → sodium salicylate NTA trick: Carboxylation of phenol at ortho position.

22. Hoffmann Bromamide Reaction

Reagent: Br₂ + NaOH Converts: Primary amide (RCONH₂) → primary amine (RNH₂) — one carbon less NTA trick: This is one of the very few reactions that decreases carbon count. Frequently tested.

23. Hell-Volhard-Zelinsky (HVZ) Reaction

Reagent: Br₂ + red phosphorus Converts: Carboxylic acid → α-bromo carboxylic acid NTA trick: Requires P catalyst; does NOT work on acids without α-H.

24. Schmidt Reaction

Reagent: HN₃ (hydrazoic acid) + H₂SO₄ Converts: Carboxylic acid → amine (one carbon less); ketone → amide NTA trick: Like Hoffmann, loses a carbon when starting from acid.

25. Diels-Alder Reaction

Reagent: Diene + dienophile (heat) Product: Cyclohexene derivative NTA trick: Diene must be in s-cis conformation. Electron-rich diene + electron-poor dienophile gives fastest reaction. Stereochemistry: syn addition (endo/exo products).

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How to Memorise These for JEE

Do NOT try to memorise all 35 at once. Here's the efficient method:

Week 1: Learn reactions 1–10. For each, write a single sentence: reagent → substrate → product → the one trick.

Week 2: Learn reactions 11–25. Same format.

Week 3: Do 15–20 named reaction questions per day on ExamBattle or PYQ banks. Every wrong answer → revisit that reaction in your notes.

Revision trick: Write just the reaction names on a blank sheet. Try to recall reagent, substrate, product, and NTA trick for each one from memory. Check against your notes. Repeat weekly.

By JEE day, you should be able to recall any of these in under 10 seconds. That's the target.