Chemistry - 3.3.14: Organic Synthesis

Ester hydrolysis by acids?

Reagents: Water, acid

Conditions: Heated under reflux, dilute acid

Alcohol to ketone?

Name of reaction: Oxidation

Reagents: Acidified potassium dichromate (acidified with H₂SO₄)

Conditions: Excess potassium dichromate, concentrated acid, heat under reflux

Ketone to secondary alcohol?

Name of mechanism: Nucleophilic addition

Reagents: NaBH₄

Conditions: Aqueous solution

Halogenoalkane to alcohol?

Name of mechanism: Nucleophilic substitution

Reagents: NaOH / KOH

Conditions: Heat under reflux, aqueous

Halogenoalkane to alkene?

Name of mechanism: Elimination

Reagents: NaOH / KOH

Conditions: Heat under reflux, ethanolic

Alcohol to alkene?

Name of mechanism: Elimination / Dehydration

Reagents: -

Conditions: Concentrated H₂SO₄ / H₃PO₄, high temperature

Alcohol to aldehyde?

Name of reaction: Oxidation

Reagents: Acidified potassium dichromate (acidified with H₂SO₄)

Conditions: Dilute potassium dichromate, dilute acid, distillation

Halogenoalkane to amine?

Name of mechanism: Nucleophilic substitution

Reagents: Ammonia

Conditions: Heated under pressure, excess ammonia, ethanolic

Alkane to halogenoalkane?

Name of mechanism: Free radical substitution

Reagents: X₂

Conditions: UV light

Alkene to halogenoalkane?

Name of mechanism: Electrophilic addition

Reagents: HX, X₂ (if di-halo)

Conditions: Room temperature

Alkene to alcohol?

Name of reaction: Hydration

Reagents: H₂O, phosphoric acid catalyst

Conditions: Concentrated acid, heat, high pressure then distillation

Nitrile to amine?

Name of mechanism: Reduction

Reagents: H₂ gas and nickel catalyst

Conditions: High temperature and pressure

Halogenoalkane to nitrile?

Name of mechanism: Nucleophilic substitution

Reagents: KCN

Conditions: Heat under reflux, ethanolic and aqueous

Acyl chloride to amide?

Name of mechanism: Nucleophilic addition-elimination

Reagents: Ammonia OR an amine for an N-substituted amide

Conditions: Cold, concentrated ammonia

Acyl chloride / acid anhydride to carboxylic acid?

Name of mechanism: Nucleophilic addition-elimination

Reagents: Water

Conditions: Cold…water….?

Aldehyde to carboxylic acid?

Name of reaction: Oxidation

Reagents: Acidified potassium dichromate (acidified with H₂SO₄)

Conditions: Excess potassium dichromate, concentrated acid, heat under reflux

Ester hydrolysis by bases?

Reagents: NaOH, then strong acid to separate carboxylic acid from carboxylate salt

Conditions: Heated under reflux, dilute alkali, excess acid

Formation of an ester?

Name of reaction: Esterification

Reagents: Carboxylic acid, alcohol, H₂SO₄ catalyst

Conditions: Heat, concentrated acid

Acyl chloride / acid anhydride to ester?

Name of mechanism: Nucleophilic addition-elimination

Reagents: Alcohol

Conditions: Room temperature

Alcohol to carboxylic acid?

Name of reaction: Oxidation

Reagents: Acidified potassium dichromate (acidified with H₂SO₄)

Conditions: Excess potassium dichromate, concentrated acid, heat under reflux

Aldehyde to primary alcohol?

Name of mechanism: Nucleophilic addition

Reagents: NaBH₄

Conditions: Aqueous solution

What will NaBH₄ reduce? What will it not reduce?

It will reduce C=O
It will NOT reduce C=C

What will H₂ with a Ni catalyst reduce? What will it not reduce?

It will reduce C=C
It will NOT reduce C=O

What will Sn and HCl reduce?

R-NO₂

Benzene to nitrobenzene?

Name of mechanism: Electrophilic substitution

Reagents: HNO₃ and H₂SO₄

Conditions: Concentrated acid

Nitrobenzene to phenylamine?

Name of mechanism: Reduction

Reagents: Sn and HCl, then NaOH

Conditions: Concentrated acid, heat

Test for alkenes?

Add bromine water - changes from orange to colourless (decolourises)

Test for halogenoalkanes?

Warm with NaOH, then add acidified silver nitrate (with HNO₃) - coloured silver halide precipitate forms

Test for alcohols?

Add acidified potassium dichromate - primary and secondary alcohols change colour from orange to green, tertiary alcohols will not

Test for aldehydes?

Add Tollens’ reagent - silver mirror forms

OR Add Fehling’s solution - brick red precipitate forms

Test for carboxylic acids?

Add sodium hydrogencarbonate - effervescence

Adding an acyl group to benzene?

Name of mechanism: Electrophilic substitution (Friedel-Crafts acylation)

Reagents: Acyl chloride

Conditions: AlCl₃ catalyst, (heat under reflux) in a non-aqueous solvent / dry ether

In the nucleophilic substitution of a halogenoalkane with ammonia, why is heating under reflux not used?

Ammonia would not be condensed by the condenser

Aldehyde / Ketone to hydroxynitrile

Name of mechanism: Nucleophilic addition

Reagents: KCN

Conditions: (Dilute) H₂SO₄

Alkene to alkane

Name of mechanism: Reduction

Reagents: H₂ gas, nickel catalyst

Conditions: 150°C

Polyamide hydrolysis

Reagent: HCl / NaOH

Conditions: Heat under reflux

How can silver nitrate solution be used to distinguish between an acyl chloride and a chloroalkane?

Acyl chloride: White precipitate forms (immediately)

Chloroalkane: No visible change (/ white precipitate forms very slowly)