JEE Mains Chemistry · Organic Reaction Mechanisms

Named Reactions

Each named reaction is a fixed triple of name, reagent and change, and the questions test it by giving one of the three and asking for another, usually four at a time in a match list.

All Organic Reaction Mechanisms notes JEE Mains Chemistry strategy

Why this matters

Twelve PYQs, nine of them match lists and one asking for a number. Four pair halide and diazonium reactions with their names and reagents: Wurtz, Fittig, Wurtz-Fittig, Finkelstein, Sandmeyer, Gattermann, Lucas, and the two routes to an isocyanide. Four pair carbonyl, acid and amide reactions: Rosenmund, Clemmensen, HVZ, Hofmann bromamide, Etard, Gattermann-Koch, Cannizzaro, Reimer-Tiemann. Four ask for a mechanism class or a reagent's job.

Concept 1 of 3: Named reactions of alkyl halides, aryl halides and diazonium salts

The halide reactions pair up in ways that are easy to mix. Sodium joins two halides: two alkyl halides (Wurtz), two aryl halides (Fittig) or one of each (Wurtz-Fittig). A halogen is swapped for another by a salt whose by-product drops out: NaI in dry acetone makes iodides, metal fluorides make fluorides. A diazonium group is replaced by halogen with a copper(I) salt (Sandmeyer) or with copper powder and the acid (Gattermann).

Definition

Coupling with Na in dry ether: RX + RX → R–R (Wurtz); ArX + ArX → Ar–Ar (Fittig); ArX + RX → Ar–R (Wurtz-Fittig).
Finkelstein: NaI in dry acetone turns R–Cl or R–Br into R–I; NaCl or NaBr is insoluble in acetone and precipitates, which drives the reaction.
Swarts: AgF, $\mathrm{Hg_2F_2}$ , $\mathrm{CoF_2}$ or $\mathrm{SbF_3}$ turns R–Cl or R–Br into R–F.
Sandmeyer: $\mathrm{ArN_2^+}$ with CuCl/HCl (cuprous chloride, often written $\mathrm{Cu_2Cl_2}$ ), CuBr/HBr or CuCN gives ArCl, ArBr or ArCN. Gattermann: copper powder with HCl or HBr gives ArCl or ArBr.
Lucas reagent (conc. HCl with anhydrous $\mathrm{ZnCl_2}$ ) turns an alcohol into the chloride: at once for a tertiary alcohol, in about five minutes for a secondary, not at room temperature for a primary.
Cyanide or isocyanide: KCN is ionic and attacks through C, giving the nitrile R–CN. AgCN is covalent and attacks through N, giving the isocyanide R–NC. A primary amine with $\mathrm{CHCl_3}$ and alcoholic KOH (carbylamine reaction) also gives R–NC.

Name	Reagent	Change	Example
Wurtz	Na, dry ether	2 RX → R–R	$\mathrm{2\,CH_3CH_2Br \to CH_3CH_2CH_2CH_3}$
Fittig	Na, dry ether	2 ArX → Ar–Ar	$\mathrm{2\,C_6H_5Br \to C_6H_5{-}C_6H_5}$ (biphenyl)
Wurtz-Fittig	Na, dry ether	ArX + RX → Ar–R	$\mathrm{C_6H_5Br + CH_3CH_2Br \to C_6H_5CH_2CH_3}$
Finkelstein	NaI, dry acetone	R–Cl or R–Br → R–I	$\mathrm{CH_3CH_2Br \to CH_3CH_2I}$
Swarts	AgF, $\mathrm{Hg_2F_2}$ , $\mathrm{CoF_2}$ or $\mathrm{SbF_3}$	R–Cl or R–Br → R–F	$\mathrm{CH_3Br \to CH_3F}$
Sandmeyer	CuCl/HCl, CuBr/HBr or CuCN	$\mathrm{ArN_2^+}$ → ArCl, ArBr or ArCN	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5CN}$ with CuCN
Gattermann	Cu powder with HCl or HBr	$\mathrm{ArN_2^+}$ → ArCl or ArBr	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5Cl}$ with Cu/HCl
Balz-Schiemann	$\mathrm{HBF_4}$ , then heat	$\mathrm{ArN_2^+}$ → ArF	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5F}$
Lucas	Conc. HCl, anhydrous $\mathrm{ZnCl_2}$	ROH → RCl; rate 3° > 2° > 1°	$\mathrm{(CH_3)_2CHOH \to (CH_3)_2CHCl}$ , cloudy in about 5 min
Nitrile from KCN	KCN (ionic)	RX → R–CN	$\mathrm{CH_3CH_2Br \to CH_3CH_2CN}$
Isocyanide from AgCN	AgCN (covalent)	RX → R–NC	$\mathrm{CH_3CH_2Br \to CH_3CH_2NC}$
Carbylamine	$\mathrm{CHCl_3}$ , alcoholic KOH	Primary amine $\mathrm{RNH_2}$ → R–NC	$\mathrm{C_6H_5NH_2 \to C_6H_5NC}$ , a foul smell

Sodium couples, halide salts swap, copper replaces a diazonium group, silver cyanide attacks through nitrogen.

Practice this conceptself-check · 4 quick reps

The same idea in a real exam question:

JEE Mains · 2023 · 30 January 2023 · Q49Moderate

Example 1 · Organic Reaction Mechanisms · Named Reactions

Match List I with List II Choose the correct answer from the options given below:

Sandmeyer uses a copper(I) salt, Gattermann uses copper powder

Both replace

\mathrm{N_2^+}

by Cl or Br. CuCl with HCl (or CuBr with HBr) is Sandmeyer; Cu powder with HCl or HBr is Gattermann. A match list that pairs 'Cu, HCl' with Sandmeyer is wrong.

AgCN gives the isocyanide, KCN the nitrile

KCN is ionic, and the free cyanide ion attacks through its carbon. AgCN is largely covalent, so the nitrogen lone pair attacks. The same alkyl halide gives R–CN with KCN and R–NC with AgCN.

Wurtz-Fittig needs one aryl and one alkyl halide

Two aryl halides with sodium is the Fittig reaction and gives a biaryl; two alkyl halides is the Wurtz reaction. Only the mixed pair, ArX with RX, is Wurtz-Fittig and gives an alkylbenzene.

Drill 3 more on named reactions of alkyl halides, aryl halides and diazonium salts

Concept 2 of 3: Named reactions of carbonyls, acids, amides and phenols

These named reactions each make or remove one specific group, so they are best learned as 'from what to what'. Three make an aldehyde (Rosenmund from an acid chloride, Etard from a methylarene, Gattermann-Koch from benzene itself), two take C=O to

\mathrm{CH_2}

(Clemmensen in acid, Wolff-Kishner in base), and the rest each own one change: HVZ puts a halogen next to COOH, Hofmann bromamide removes the amide carbon, Reimer-Tiemann puts CHO on a phenol.

Definition

Aldehyde-making: Rosenmund $\mathrm{RCOCl \to RCHO}$ ( $\mathrm{H_2}$ , Pd on $\mathrm{BaSO_4}$ , poisoned so it stops at CHO); Stephen RCN → RCHO ( $\mathrm{SnCl_2/HCl}$ , then $\mathrm{H_3O^+}$ ); Etard $\mathrm{ArCH_3 \to ArCHO}$ ; Gattermann-Koch ArH → ArCHO (CO, HCl, anhydrous $\mathrm{AlCl_3}$ ).
C=O to $\mathrm{CH_2}$ : Clemmensen (Zn–Hg, conc. HCl) or Wolff-Kishner (hydrazine, then KOH in ethylene glycol).
HVZ: $\mathrm{Cl_2}$ or $\mathrm{Br_2}$ with red phosphorus, then water, halogenates the α-carbon of a carboxylic acid.
Hofmann bromamide: $\mathrm{Br_2}$ and NaOH turn $\mathrm{RCONH_2}$ into $\mathrm{RNH_2}$ , one carbon shorter, through an isocyanate.
Reimer-Tiemann: $\mathrm{CHCl_3}$ and aqueous NaOH, then acid, put CHO ortho to the OH of phenol. Kolbe: sodium phenoxide with $\mathrm{CO_2}$ (4–7 atm, 400 K), then acid, gives salicylic acid.
Friedel-Crafts acylation with $\mathrm{C_6H_5COCl}$ gives benzophenone, a ketone, not diphenylmethane.

Name	Reagent	Change	Example
Rosenmund	$\mathrm{H_2}$ , Pd on $\mathrm{BaSO_4}$	RCOCl → RCHO	$\mathrm{CH_3COCl \to CH_3CHO}$
Stephen	$\mathrm{SnCl_2/HCl}$ , then $\mathrm{H_3O^+}$	RCN → RCHO	$\mathrm{CH_3CN \to CH_3CHO}$
Etard	$\mathrm{CrO_2Cl_2}$ in $\mathrm{CS_2}$ , then $\mathrm{H_3O^+}$	$\mathrm{ArCH_3}$ → ArCHO	Toluene → benzaldehyde
Gattermann-Koch	CO, HCl, anhydrous $\mathrm{AlCl_3}$ (CuCl)	ArH → ArCHO	Benzene → benzaldehyde
Clemmensen	Zn–Hg, conc. HCl	C=O → $\mathrm{CH_2}$ , in acid	$\mathrm{CH_3COCH_3 \to CH_3CH_2CH_3}$
Wolff-Kishner	$\mathrm{NH_2NH_2}$ , then KOH in ethylene glycol, heat	C=O → $\mathrm{CH_2}$ , in base	$\mathrm{C_6H_5COCH_2CH_3 \to C_6H_5CH_2CH_2CH_3}$
Cannizzaro	Concentrated NaOH or KOH	2 RCHO (no α-H) → $\mathrm{RCH_2OH + RCOO^-}$	$\mathrm{2\,HCHO \to CH_3OH + HCOO^-}$
Aldol	Dilute NaOH	Two carbonyls with α-H → β-hydroxy carbonyl	$\mathrm{2\,CH_3CHO \to CH_3CH(OH)CH_2CHO}$
Hell-Volhard-Zelinsky (HVZ)	$\mathrm{Cl_2}$ or $\mathrm{Br_2}$ , red P, then $\mathrm{H_2O}$	$\mathrm{RCH_2COOH \to RCHXCOOH}$	$\mathrm{CH_3COOH \to ClCH_2COOH}$
Hofmann bromamide	$\mathrm{Br_2}$ , NaOH	$\mathrm{RCONH_2 \to RNH_2}$ , one carbon fewer	$\mathrm{C_6H_5CONH_2 \to C_6H_5NH_2}$
Reimer-Tiemann	$\mathrm{CHCl_3}$ , aqueous NaOH, then $\mathrm{H_3O^+}$	Phenol → 2-hydroxybenzaldehyde	$\mathrm{C_6H_5OH \to HOC_6H_4CHO}$ (salicylaldehyde)
Kolbe	NaOH, $\mathrm{CO_2}$ at 4–7 atm and 400 K, then $\mathrm{H^+}$	Phenol → 2-hydroxybenzoic acid	$\mathrm{C_6H_5OH \to HOC_6H_4COOH}$ (salicylic acid)
Haloform	$\mathrm{X_2}$ , NaOH	$\mathrm{CH_3COR \to CHX_3 + RCOO^-}$	$\mathrm{CH_3COCH_3 \to CHI_3 + CH_3COO^-}$
Decarboxylation	Soda lime (NaOH and CaO), heat	RCOONa → RH	$\mathrm{CH_3COONa \to CH_4}$

Learn each row as reagent plus change; a match list gives you one and asks for the other.

Practice this conceptself-check · 4 quick reps

The same idea in a real exam question:

JEE Mains · 2021 · Paper 2 · Q48Moderate

Example 2 · Organic Reaction Mechanisms · Named Reactions

Match List-I with List-II (shown in the figure) and choose the correct answer:

Rosenmund stops at the aldehyde

The palladium is poisoned with

\mathrm{BaSO_4}

so that

\mathrm{H_2}

reduces the acid chloride only as far as the aldehyde. The product is never the carboxylic acid, and with an unpoisoned catalyst it would go on to the alcohol.

Hofmann bromamide loses a carbon

The carbonyl carbon of the amide leaves as carbonate, so benzamide gives aniline and propanamide gives ethanamine. Acid hydrolysis of an amide, by contrast, keeps every carbon and gives the carboxylic acid.

Reimer-Tiemann gives an aldehyde, Kolbe gives an acid

Both work ortho to the OH of phenol. Chloroform and alkali (Reimer-Tiemann) add CHO; carbon dioxide under pressure with sodium phenoxide (Kolbe) adds COOH.

Drill 3 more on named reactions of carbonyls, acids, amides and phenols

Concept 3 of 3: Mechanism class and reagent roles

Every reaction has a class, set by what attacks what. A nucleophile replacing a leaving group is a nucleophilic substitution; an electrophile replacing an H on a ring is an electrophilic substitution; an electrophile adding across a C=C is an electrophilic addition; a halogen atom made by light is a free-radical reaction. Name the attacking species and the class follows.

Definition

Nucleophilic substitution: $\mathrm{S_N2}$ for a primary halide with a strong nucleophile (Williamson ether synthesis); $\mathrm{S_N1}$ through a carbocation for a tertiary halide in water.
Electrophilic substitution: an arene with $\mathrm{NO_2^+}$ , $\mathrm{R^+}$ , $\mathrm{RCO^+}$ or $\mathrm{Cl^+}$ (from $\mathrm{Cl_2/FeCl_3}$ ).
Electrophilic addition: $\mathrm{Br_2}$ or HX across a C=C, including the side chain of styrene.
Nucleophilic addition: HCN, Grignard reagents or $\mathrm{NaHSO_3}$ on a C=O.
Free radical: $\mathrm{Cl_2}$ with light on an alkane or on the side chain of toluene (substitution); $\mathrm{Cl_2}$ on benzene in UV light with no catalyst (addition, giving benzene hexachloride, $\mathrm{C_6H_6Cl_6}$ ).
Elimination: alcoholic KOH on an alkyl halide (β-elimination, Saytzeff alkene); Hofmann elimination of a quaternary ammonium hydroxide gives the less substituted (anti-Saytzeff) alkene.
Reducing systems: $\mathrm{H_2}$ with Pt, Pd or Ni; Lindlar's catalyst (Pd on $\mathrm{BaSO_4}$ or $\mathrm{CaCO_3}$ , poisoned) stops an alkyne at the cis-alkene; Na in liquid $\mathrm{NH_3}$ gives the trans-alkene; Zn with water or acid. Sodium with $\mathrm{H_2}$ only forms NaH and reduces nothing.

Reaction or reagent	Class or role	Key species	Result
Williamson synthesis: RONa + primary RX	Nucleophilic substitution ( $\mathrm{S_N2}$ )	Alkoxide ion	Ether
tert-Butyl bromide in water	Nucleophilic substitution ( $\mathrm{S_N1}$ )	Tertiary carbocation	2-Methylpropan-2-ol
Nitration, sulphonation, Friedel-Crafts	Electrophilic substitution	$\mathrm{NO_2^+}$ , $\mathrm{SO_3}$ , $\mathrm{R^+}$ or $\mathrm{RCO^+}$	Substituted arene
$\mathrm{Br_2}$ on an alkene	Electrophilic addition	Cyclic bromonium ion	Vicinal dibromide
HCN on a ketone	Nucleophilic addition	Cyanide ion	Cyanohydrin
$\mathrm{Cl_2}$ on methane or on toluene's side chain, in light	Free-radical substitution	Cl atom; methyl or benzyl radical	Chloromethane or benzyl chloride
$\mathrm{Cl_2}$ on benzene in UV light, no catalyst	Free-radical addition	Cl atom	Benzene hexachloride, $\mathrm{C_6H_6Cl_6}$
Alcoholic KOH on an alkyl halide	β-Elimination	Strong base in ethanol	Alkene, the more substituted one
Heating a quaternary ammonium hydroxide	Hofmann elimination	Bulky trialkylamine leaving group	The less substituted (anti-Saytzeff) alkene
Lindlar's catalyst with $\mathrm{H_2}$	Partial hydrogenation	Poisoned palladium	Alkyne to cis-alkene
Na in liquid $\mathrm{NH_3}$	Dissolving-metal reduction	Solvated electrons	Alkyne to trans-alkene
Hinsberg reagent, $\mathrm{C_6H_5SO_2Cl}$	Test that sorts amines	Sulphonamide	1° dissolves in alkali, 2° does not, 3° does not react
Na with $\mathrm{H_2}$	Not a reducing system for organic groups	Sodium hydride forms	No organic group is reduced

Name the species that attacks and whether it adds or replaces; the class follows from those two facts.

Practice this conceptself-check · 4 quick reps

The same idea in a real exam question:

JEE Mains · 2026 · 4 Apr 2026 Shift 2 · Q31Moderate

Example 3 · Organic Reaction Mechanisms · Named Reactions

Match the LIST-I with LIST-II

	List-I Reaction		List-II Mechanism
(A)	Williamson Synthesis	(I)	Electrophilic addition
(B)	Friedel-Crafts reaction	(II)	Free radical substitution
(C)	Bromination of vinyl benzene	(III)	Nucleophilic substitution
(D)	Chlorination of toluene in light	(IV)	Electrophilic substitution

Choose the correct answer from the options given below:

Toluene and chlorine: light or catalyst decides where

In light or on heating, chlorine atoms take a benzylic H and give benzyl chloride: free-radical substitution on the side chain. With

\mathrm{FeCl_3}

in the dark,

\mathrm{Cl^+}

attacks the ring: electrophilic substitution at ortho and para.

Benzene hexachloride is an addition product

Benzene with chlorine in UV light and no catalyst adds three

\mathrm{Cl_2}

molecules to give

\mathrm{C_6H_6Cl_6}

. It is not chlorobenzene and not a substitution.

Alcoholic KOH eliminates, aqueous KOH substitutes

In ethanol, KOH acts as a strong base and removes a β-hydrogen to give an alkene. In water, hydroxide acts as a nucleophile and replaces the halogen to give an alcohol.

Drill 3 more on mechanism class and reagent roles

Summary — formulas & gotchas at a glance

A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.

Reference tables (3)

Named reactions of alkyl halides, aryl halides and diazonium salts12 rows

Name	Reagent	Change	Example
Wurtz	Na, dry ether	2 RX → R–R	$\mathrm{2\,CH_3CH_2Br \to CH_3CH_2CH_2CH_3}$
Fittig	Na, dry ether	2 ArX → Ar–Ar	$\mathrm{2\,C_6H_5Br \to C_6H_5{-}C_6H_5}$ (biphenyl)
Wurtz-Fittig	Na, dry ether	ArX + RX → Ar–R	$\mathrm{C_6H_5Br + CH_3CH_2Br \to C_6H_5CH_2CH_3}$
Finkelstein	NaI, dry acetone	R–Cl or R–Br → R–I	$\mathrm{CH_3CH_2Br \to CH_3CH_2I}$
Swarts	AgF, $\mathrm{Hg_2F_2}$ , $\mathrm{CoF_2}$ or $\mathrm{SbF_3}$	R–Cl or R–Br → R–F	$\mathrm{CH_3Br \to CH_3F}$
Sandmeyer	CuCl/HCl, CuBr/HBr or CuCN	$\mathrm{ArN_2^+}$ → ArCl, ArBr or ArCN	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5CN}$ with CuCN
Gattermann	Cu powder with HCl or HBr	$\mathrm{ArN_2^+}$ → ArCl or ArBr	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5Cl}$ with Cu/HCl
Balz-Schiemann	$\mathrm{HBF_4}$ , then heat	$\mathrm{ArN_2^+}$ → ArF	$\mathrm{C_6H_5N_2^+Cl^- \to C_6H_5F}$
Lucas	Conc. HCl, anhydrous $\mathrm{ZnCl_2}$	ROH → RCl; rate 3° > 2° > 1°	$\mathrm{(CH_3)_2CHOH \to (CH_3)_2CHCl}$ , cloudy in about 5 min
Nitrile from KCN	KCN (ionic)	RX → R–CN	$\mathrm{CH_3CH_2Br \to CH_3CH_2CN}$
Isocyanide from AgCN	AgCN (covalent)	RX → R–NC	$\mathrm{CH_3CH_2Br \to CH_3CH_2NC}$
Carbylamine	$\mathrm{CHCl_3}$ , alcoholic KOH	Primary amine $\mathrm{RNH_2}$ → R–NC	$\mathrm{C_6H_5NH_2 \to C_6H_5NC}$ , a foul smell

Sodium couples, halide salts swap, copper replaces a diazonium group, silver cyanide attacks through nitrogen.

Named reactions of carbonyls, acids, amides and phenols14 rows

Name	Reagent	Change	Example
Rosenmund	$\mathrm{H_2}$ , Pd on $\mathrm{BaSO_4}$	RCOCl → RCHO	$\mathrm{CH_3COCl \to CH_3CHO}$
Stephen	$\mathrm{SnCl_2/HCl}$ , then $\mathrm{H_3O^+}$	RCN → RCHO	$\mathrm{CH_3CN \to CH_3CHO}$
Etard	$\mathrm{CrO_2Cl_2}$ in $\mathrm{CS_2}$ , then $\mathrm{H_3O^+}$	$\mathrm{ArCH_3}$ → ArCHO	Toluene → benzaldehyde
Gattermann-Koch	CO, HCl, anhydrous $\mathrm{AlCl_3}$ (CuCl)	ArH → ArCHO	Benzene → benzaldehyde
Clemmensen	Zn–Hg, conc. HCl	C=O → $\mathrm{CH_2}$ , in acid	$\mathrm{CH_3COCH_3 \to CH_3CH_2CH_3}$
Wolff-Kishner	$\mathrm{NH_2NH_2}$ , then KOH in ethylene glycol, heat	C=O → $\mathrm{CH_2}$ , in base	$\mathrm{C_6H_5COCH_2CH_3 \to C_6H_5CH_2CH_2CH_3}$
Cannizzaro	Concentrated NaOH or KOH	2 RCHO (no α-H) → $\mathrm{RCH_2OH + RCOO^-}$	$\mathrm{2\,HCHO \to CH_3OH + HCOO^-}$
Aldol	Dilute NaOH	Two carbonyls with α-H → β-hydroxy carbonyl	$\mathrm{2\,CH_3CHO \to CH_3CH(OH)CH_2CHO}$
Hell-Volhard-Zelinsky (HVZ)	$\mathrm{Cl_2}$ or $\mathrm{Br_2}$ , red P, then $\mathrm{H_2O}$	$\mathrm{RCH_2COOH \to RCHXCOOH}$	$\mathrm{CH_3COOH \to ClCH_2COOH}$
Hofmann bromamide	$\mathrm{Br_2}$ , NaOH	$\mathrm{RCONH_2 \to RNH_2}$ , one carbon fewer	$\mathrm{C_6H_5CONH_2 \to C_6H_5NH_2}$
Reimer-Tiemann	$\mathrm{CHCl_3}$ , aqueous NaOH, then $\mathrm{H_3O^+}$	Phenol → 2-hydroxybenzaldehyde	$\mathrm{C_6H_5OH \to HOC_6H_4CHO}$ (salicylaldehyde)
Kolbe	NaOH, $\mathrm{CO_2}$ at 4–7 atm and 400 K, then $\mathrm{H^+}$	Phenol → 2-hydroxybenzoic acid	$\mathrm{C_6H_5OH \to HOC_6H_4COOH}$ (salicylic acid)
Haloform	$\mathrm{X_2}$ , NaOH	$\mathrm{CH_3COR \to CHX_3 + RCOO^-}$	$\mathrm{CH_3COCH_3 \to CHI_3 + CH_3COO^-}$
Decarboxylation	Soda lime (NaOH and CaO), heat	RCOONa → RH	$\mathrm{CH_3COONa \to CH_4}$

Learn each row as reagent plus change; a match list gives you one and asks for the other.

Mechanism class and reagent roles13 rows

Reaction or reagent	Class or role	Key species	Result
Williamson synthesis: RONa + primary RX	Nucleophilic substitution ( $\mathrm{S_N2}$ )	Alkoxide ion	Ether
tert-Butyl bromide in water	Nucleophilic substitution ( $\mathrm{S_N1}$ )	Tertiary carbocation	2-Methylpropan-2-ol
Nitration, sulphonation, Friedel-Crafts	Electrophilic substitution	$\mathrm{NO_2^+}$ , $\mathrm{SO_3}$ , $\mathrm{R^+}$ or $\mathrm{RCO^+}$	Substituted arene
$\mathrm{Br_2}$ on an alkene	Electrophilic addition	Cyclic bromonium ion	Vicinal dibromide
HCN on a ketone	Nucleophilic addition	Cyanide ion	Cyanohydrin
$\mathrm{Cl_2}$ on methane or on toluene's side chain, in light	Free-radical substitution	Cl atom; methyl or benzyl radical	Chloromethane or benzyl chloride
$\mathrm{Cl_2}$ on benzene in UV light, no catalyst	Free-radical addition	Cl atom	Benzene hexachloride, $\mathrm{C_6H_6Cl_6}$
Alcoholic KOH on an alkyl halide	β-Elimination	Strong base in ethanol	Alkene, the more substituted one
Heating a quaternary ammonium hydroxide	Hofmann elimination	Bulky trialkylamine leaving group	The less substituted (anti-Saytzeff) alkene
Lindlar's catalyst with $\mathrm{H_2}$	Partial hydrogenation	Poisoned palladium	Alkyne to cis-alkene
Na in liquid $\mathrm{NH_3}$	Dissolving-metal reduction	Solvated electrons	Alkyne to trans-alkene
Hinsberg reagent, $\mathrm{C_6H_5SO_2Cl}$	Test that sorts amines	Sulphonamide	1° dissolves in alkali, 2° does not, 3° does not react
Na with $\mathrm{H_2}$	Not a reducing system for organic groups	Sodium hydride forms	No organic group is reduced

Name the species that attacks and whether it adds or replaces; the class follows from those two facts.

Watch out for (9)

Sandmeyer uses a copper(I) salt, Gattermann uses copper powder
→ Named reactions of alkyl halides, aryl halides and diazonium salts
AgCN gives the isocyanide, KCN the nitrile
→ Named reactions of alkyl halides, aryl halides and diazonium salts
Wurtz-Fittig needs one aryl and one alkyl halide
→ Named reactions of alkyl halides, aryl halides and diazonium salts
Rosenmund stops at the aldehyde
→ Named reactions of carbonyls, acids, amides and phenols
Hofmann bromamide loses a carbon
→ Named reactions of carbonyls, acids, amides and phenols
Reimer-Tiemann gives an aldehyde, Kolbe gives an acid
→ Named reactions of carbonyls, acids, amides and phenols
Toluene and chlorine: light or catalyst decides where
→ Mechanism class and reagent roles
Benzene hexachloride is an addition product
→ Mechanism class and reagent roles
Alcoholic KOH eliminates, aqueous KOH substitutes
→ Mechanism class and reagent roles

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