Amines
Unit IX. Covers Structure, classification and nomenclature; Preparation and properties; Diazonium salts.
About this unit
Amines are organic derivatives of ammonia in which one or more hydrogen atoms are replaced by alkyl or aryl groups. They occur in proteins, vitamins, alkaloids and hormones, and are used to make dyes, drugs and polymers. Diazonium salts, made from aromatic primary amines, are among the most useful intermediates in aromatic synthesis.
Key ideas
- Classification into primary (RNH₂), secondary (R₂NH) and tertiary (R₃N) amines, and their IUPAC names.
- Pyramidal structure of the nitrogen atom with a lone pair.
- Preparation: reduction of nitro compounds, nitriles and amides; ammonolysis; Gabriel phthalimide synthesis; Hoffmann bromamide degradation.
- Basic character and the factors that decide the order of basicity in water.
- Distinguishing tests: carbylamine reaction and Hinsberg's test.
- Diazonium salts and their replacement and coupling reactions.
How to prepare
- Learn the basicity order of methyl- and ethyl-substituted amines in water and the reasons for it.
- Make a table in your notebook of diazonium replacement reactions with the reagent and product.
- Practise conversion questions such as benzene → fluorobenzene, and questions that ask how to tell 1°, 2° and 3° amines apart.
Topics in this chapter
Structure, classification and nomenclature
Primary, secondary and tertiary amines.
5 questionsPreparation and properties
Methods of preparation, physical properties and basic character.
5 questionsDiazonium salts
Preparation, properties and importance in synthesising aromatic compounds.
5 questionsPractice questions
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