Reagents & conditions

A-level

AQA 3.3

The 30 functional-group conversions the synthesis questions are built from — reagents, conditions and reaction type, on one page. Flip on Test yourself and it's a recall drill.

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From alkenes

AlkeneHalogenoalkane

hydrogen halide (e.g. HBr) · room temperature

electrophilic addition

unsymmetrical alkenes follow Markovnikov — more stable carbocation wins

AlkeneDihalogenoalkane

halogen (e.g. Br₂) · room temperature

electrophilic addition

orange bromine water decolourises — the test for C=C

AlkeneAlcohol

steam, H₃PO₄ catalyst · high temperature & pressure

electrophilic (hydration)

AlkeneAlkane

hydrogen, Ni catalyst · ~150 °C

addition (hydrogenation)

AlkenePoly(alkene)

high pressure, catalyst · addition polymerisation

addition polymerisation

From halogenoalkanes

HalogenoalkaneAlcohol

NaOH (aqueous) · warm, reflux

nucleophilic substitution

HalogenoalkaneNitrile

KCN in ethanol · reflux

nucleophilic substitution

adds one carbon to the chain

HalogenoalkaneAmine

excess ammonia in ethanol · heat under pressure (sealed tube)

nucleophilic substitution

excess NH₃ limits further substitution to secondary/tertiary amines

HalogenoalkaneAlkene

NaOH in ethanol · reflux

elimination

ethanolic + reflux = elimination; aqueous + warm = substitution

From alcohols

Primary alcoholAldehyde

acidified K₂Cr₂O₇ · warm, distil off the aldehyde

oxidation

distil so it can't be oxidised further; orange → green

Primary alcoholCarboxylic acid

acidified K₂Cr₂O₇ (excess) · reflux

oxidation

Secondary alcoholKetone

acidified K₂Cr₂O₇ · reflux

oxidation

AlcoholAlkene

conc. H₃PO₄ or H₂SO₄ · heat

elimination (dehydration)

AlcoholHalogenoalkane

PCl₅ or SOCl₂ (→ chloro); NaBr + H₂SO₄ (→ bromo) · warm

substitution

red phosphorus + I₂ makes the iodoalkane

AlcoholEster

carboxylic acid + conc. H₂SO₄ · warm

esterification

From carbonyls (aldehydes & ketones)

AldehydePrimary alcohol

NaBH₄ · in water/methanol

nucleophilic addition (reduction)

KetoneSecondary alcohol

NaBH₄ · in water/methanol

nucleophilic addition (reduction)

Aldehyde / ketoneHydroxynitrile

KCN then dilute acid (H+) · room temperature

nucleophilic addition

adds one carbon; makes a chiral centre → racemic mixture

AldehydeCarboxylic acid

acidified K₂Cr₂O₇ · reflux

oxidation

Tollens' (silver mirror) / Fehling's distinguish aldehyde from ketone

From nitriles

NitrileAmine

H₂, Ni catalyst (or LiAlH₄) · reduction

reduction

NitrileCarboxylic acid

dilute HCl · reflux

hydrolysis

Carboxylic acids & derivatives

Carboxylic acidAcyl chloride

SOCl₂ (thionyl chloride) · room temperature

substitution

Acyl chlorideEster

alcohol · room temperature

nucleophilic addition–elimination

Acyl chloridePrimary amide

ammonia · room temperature

nucleophilic addition–elimination

Acyl chlorideN-substituted amide

primary amine · room temperature

nucleophilic addition–elimination

EsterCarboxylate salt + alcohol

NaOH (aqueous) · reflux

alkaline hydrolysis

Aromatics

BenzeneNitrobenzene

conc. HNO₃ + conc. H₂SO₄ · below 55 °C

electrophilic substitution (nitration)

NitrobenzenePhenylamine

Sn + conc. HCl, then NaOH · reflux

reduction

BenzeneAromatic ketone

acyl chloride + AlCl₃ catalyst · reflux, dry

electrophilic substitution (Friedel–Crafts acylation)

BenzeneHalogenobenzene

halogen (e.g. Cl₂) + AlCl₃ or FeCl₃ catalyst · room temperature

electrophilic substitution (halogenation)

the halogen carrier generates the electrophile

Now put them in order

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