Named reactions in organic chemistry

All 41 NCERT named reactions, rules and tests, chapter by chapter, with reagents and products. Search for any of them.

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Haloalkanes and haloarenes

Wurtz reaction: 2R–X + 2Na → R–R + 2NaX (dry ether). Joins two alkyl groups.
Wurtz–Fittig reaction: Ar–X + R–X + 2Na → Ar–R + 2NaX (dry ether).
Fittig reaction: 2Ar–X + 2Na → Ar–Ar + 2NaX (dry ether).
Finkelstein reaction: R–Cl / R–Br + NaI → R–I + NaCl / NaBr, in dry acetone.
Swarts reaction: R–Cl / R–Br + AgF, Hg₂F₂ or CoF₂ → R–F.
Sandmeyer reaction: ArN₂⁺Cl⁻ + CuCl / HCl → Ar–Cl. With CuBr / HBr → Ar–Br; with CuCN / KCN → Ar–CN.
Gattermann reaction: ArN₂⁺Cl⁻ + Cu powder / HCl → Ar–Cl (Cu / HBr → Ar–Br).
Balz–Schiemann reaction: ArN₂⁺BF₄⁻ → (heat) Ar–F + BF₃ + N₂.
Friedel–Crafts alkylation: ArH + R–Cl → Ar–R + HCl, anhydrous AlCl₃.
Friedel–Crafts acylation: ArH + RCOCl → Ar–COR + HCl, anhydrous AlCl₃.
Kharasch (peroxide) effect: Alkene + HBr with peroxide → anti-Markovnikov bromide. Works only with HBr.

Alcohols, phenols and ethers

Kolbe's reaction (Kolbe–Schmitt): Sodium phenoxide + CO₂ (about 400 K, 4–7 atm), then H⁺ → salicylic acid.
Reimer–Tiemann reaction: Phenol + CHCl₃ + aqueous NaOH, then H⁺ → salicylaldehyde (ortho-hydroxybenzaldehyde).
Williamson ether synthesis: R–O⁻Na⁺ + R′–X → R–O–R′ + NaX. Best with a primary alkyl halide.
Hydroboration–oxidation: Alkene + B₂H₆, then H₂O₂ / OH⁻ → alcohol with anti-Markovnikov orientation.
Lucas test: Conc. HCl + ZnCl₂: 3° alcohols turn cloudy at once, 2° in about 5 minutes, 1° not at room temperature.
Esterification (Fischer): RCOOH + R′OH ⇌ RCOOR′ + H₂O, with conc. H₂SO₄ as catalyst.

Aldehydes and ketones

Aldol condensation: 2CH₃CHO, dil. NaOH → CH₃CH(OH)CH₂CHO (aldol); on heating → CH₃CH=CHCHO. Needs an α-hydrogen.
Cross aldol condensation: Two different carbonyls with α-hydrogens give a mixture of four products.
Claisen–Schmidt condensation: C₆H₅CHO + CH₃COC₆H₅, dil. NaOH → C₆H₅CH=CHCOC₆H₅ (benzalacetophenone).
Cannizzaro reaction: 2HCHO + conc. NaOH → CH₃OH + HCOONa. Aldehydes with no α-hydrogen disproportionate.
Clemmensen reduction: C=O → CH₂ with zinc amalgam (Zn–Hg) and conc. HCl.
Wolff–Kishner reduction: C=O → CH₂ with NH₂NH₂, then KOH in ethylene glycol on heating.
Rosenmund reduction: RCOCl + H₂ → RCHO + HCl, over Pd on BaSO₄ (poisoned so it stops at the aldehyde).
Stephen reaction: RCN + SnCl₂ / HCl → imine; hydrolysis (H₃O⁺) → RCHO.
Etard reaction: Toluene + CrO₂Cl₂ (in CS₂) → chromium complex; H₃O⁺ → benzaldehyde.
Gattermann–Koch reaction: Benzene + CO + HCl, anhydrous AlCl₃ / CuCl → benzaldehyde.
Haloform (iodoform) reaction: CH₃CO– or CH₃CH(OH)– compounds + I₂ / NaOH → CHI₃ (yellow precipitate) + RCOO⁻Na⁺.
Tollens' test: RCHO + [Ag(NH₃)₂]⁺ → RCOO⁻ + silver mirror. Aldehydes give it; ketones don't.
Fehling's test: Aliphatic RCHO + Fehling's solution → red-brown Cu₂O. Aromatic aldehydes don't respond.

Carboxylic acids

Hell–Volhard–Zelinsky (HVZ): RCH₂COOH + X₂ / red phosphorus, then H₂O → RCH(X)COOH. Halogenates the α-carbon.
Kolbe electrolysis: Electrolysis of aqueous RCOONa → R–R + 2CO₂ (at the anode).
Decarboxylation: RCOONa + NaOH / CaO (soda lime), heat → R–H + Na₂CO₃. One carbon fewer.

Amines and diazonium salts

Hofmann bromamide degradation: RCONH₂ + Br₂ + 4NaOH → RNH₂ + Na₂CO₃ + 2NaBr + 2H₂O. The amine has one carbon fewer.
Gabriel phthalimide synthesis: Phthalimide + KOH → potassium salt; + R–X → N-alkylphthalimide; hydrolysis → R–NH₂. Gives only 1° aliphatic amines.
Carbylamine reaction: R–NH₂ + CHCl₃ + 3KOH → R–NC (foul-smelling isocyanide). Test for 1° amines only.
Hinsberg test: Benzenesulphonyl chloride: 1° amine → product soluble in alkali; 2° → insoluble; 3° → no reaction.
Diazotisation: Ar–NH₂ + NaNO₂ + HCl at 0–5 °C → ArN₂⁺Cl⁻ (benzenediazonium chloride).
Coupling reaction: ArN₂⁺Cl⁻ + phenol (mildly alkaline) → p-hydroxyazobenzene (orange dye); with aniline (mildly acidic) → p-aminoazobenzene (yellow).

Hydrocarbons

Ozonolysis: Alkene + O₃ → ozonide; Zn / H₂O → aldehydes or ketones. Locates the double bond.
Markovnikov addition: HX adds to an unsymmetrical alkene with H going to the carbon that already has more hydrogens.

How to learn named reactions

Every year, JEE Main and NEET ask several questions that are really just "which named reaction is this?". Learn each one as three things: what goes in, the reagent, and what comes out. The reagent is usually the clue in the question.

Reductions of C=O to CH₂: Clemmensen (acidic, Zn–Hg / HCl) and Wolff–Kishner (basic, NH₂NH₂ / KOH). Choose by what else is in the molecule.
No α-hydrogen? The aldehyde can't do aldol; it does Cannizzaro instead.
One carbon fewer: Hofmann bromamide, decarboxylation with soda lime.

Check your reactions with the equation balancer, and see the chemistry formula sheet for physical chemistry.

Questions students ask

How many named reactions are there in Class 12 chemistry?

NCERT Class 12 covers about 41 named reactions and tests across haloalkanes, alcohols, aldehydes and ketones, carboxylic acids and amines. This page lists all of them.

What is the difference between Cannizzaro and aldol condensation?

Aldol needs an α-hydrogen and dilute base, and joins two molecules into a β-hydroxy carbonyl. Cannizzaro happens with aldehydes that have no α-hydrogen, in concentrated base: one molecule is oxidised to the acid salt and another reduced to the alcohol.

Which test distinguishes 1°, 2° and 3° amines?

The Hinsberg test, with benzenesulphonyl chloride. The carbylamine test is positive only for primary amines.