• Amides?are organic compounds with an -CONR2?functional group
• They can be prepared from the?condensation reaction?between an?acyl chloride?and?ammonia?or?amine
• In a?condensation?reaction, two organic molecules?join together?and in the process?eliminate?a small molecule
• In this case, the acyl chlorides and ammonia or amine?join together?to form an?amide?and?eliminate?an HCl molecule

Condensation reaction

• The chlorine atom in acyl chlorides is?electronegative?and draws electron density from the carbonyl carbon
• The carbonyl carbon is therefore?electron-deficient?and can be attacked by?nucleophiles
• The nitrogen atom in ammonia and amines has a lone pair of electrons which can act as a?nucleophile?and attack the carbonyl carbon
• As a result, the C-Cl bond is?broken?and an?amide?is formed
• Whether the product is a?substituted?amide or not, depends on the nature of the?nucleophile
  • Primary and secondary amines will give a?substituted amide
  • The reaction of acyl chlorides with ammonia will produce a?non-substituted amide

   

Acyl chlorides undergo condensation reactions with ammonia and amines to form amides

• Note that ammonia is basic and the inorganic product is acidic, so there will be a reaction between the two molecules

NH3?+ HCl → NH4Cl

• We can therefore write the overall equation for the reaction of propanoyl chloride and ammonia as

CH3CH2COCl + 2NH3?→ CH3CH2CONH2?+ NH4Cl

Amide link

• Polyamides are also formed using condensation polymerisation

An amide link - also known as a peptide link - is the key functional group in a polyamide

Monomers

• A diamine and a dicarboxylic acid are required to form a polyamide
  • A diamine contains 2 -NH2?groups
  • A dicarboxylic acid contains 2 -COOH groups

The monomers for making polyamides

Formation of polyamides

This shows the expulsion of a small molecule as the amide link forms

• Nylon 6,6 is a synthetic polyamide
• Its monomers are 1,6-diaminohexane and hexane-1,6-dioic acid
  • The ‘6,6’ part of its name arises from the 6 carbon atoms in each of Nylon 6,6 monomers

Nylon 6,6 is a synthetic polyamide made using diamine and dicarboxylic acid monomers

Kevlar

• Kevlar is another example of a polymer formed through condensation polymerisation
• The polymer chains are neatly arranged with many hydrogen bonds between them
• This results in a strong and flexible polymer material with fire resistance properties
• These properties also lend Kevlar to a vital application in bullet-proof vests
• The monomers used to make Kevlar
  • 1,4-diaminobenzene
  • Benzene-1,4-dicarboxylic acid

Kevlar is made using a diamine and dicarboxylic acid monomers