Amides and Nitriles

How are amides formed?

1. React the acid with basic ammonia to give the ammonium carboxylate salt. Heat the salt; this results in water being lost and the amide is produced.

2. Heat the acid or its ammonium salt with urea at 120°C.

What reaction do amides undergo to form nitriles?

Amides undergo dehydration reactions to form nitriles.

P₄O₁₀ is used.

How else are nitriles formed?

From halogenoalkanes.

Reagents: Potassium cyanide (KCN) using an alcohol-water mixture as a solvent.

Conditions: Heated under reflux.

What type of reaction occurs when forming nitriles from halogenoalkanes?

Nucleophilic substitution.

Do aromatic halogenolkanes react with cyanide ions?

No- the ring carbon atoms are not suspectible to nucleophilic attack.

How are hydroxynitriles formed?

By reacting aldehydes / ketones with hydrogen cyanide (HCN) in the presence of sodium or potassium cyanide.

Nitriles are hydrolysed to form what?

Carboxylic acids.

State what reagents / conditions are needed to hydrolyse nitriles to carboxylic acids.

The reaction is heated under reflux with a dilute acid (H₂SO₄).

Describe what happens during hydrolysis of amides.

• This reaction is carried out by heating the amide, under r-eflux, with aqueous sodium hydroxide.

• The carbon-nitrogen bond is broken, giving the sodium carboxylate ion and a nitrogen containing compound. The nitrogen containing compound differs depending on whether the nitrogen was substituted or not.

Again, the carboxylic acid can be obtained by acidification (reprotonation) using a dilute acid.

Nitriles are converted to primary amines in what type of reaction?

Reduction reaction.

LiAlH₄ dissolved in ethoxyethane is used.