INTRODUCTION
Amines form an important class of organic compounds which are derived by replacing one or more hydrogen atoms of ammonia molecules by alkyl/aryl group(s). In nature, they are found among proteins, vitamins, alkaloids and hormones. Synthetic examples include polymers, dyestuffs and drugs. Adrenaline and Ephedrine, are two biologically active compounds, both of which contain a secondary amino group and are used to increase blood pressure. Novocain is a synthetic amino compound, which is used as an anaesthetic in dentistry. Benadryl, a well-known antihistaminic drug also contains a tertiary amino group. Many Quaternary ammonium salts are used as surfactants. Diazonium salts are found as intermediates in the preparation of a variety of aromatic compounds including dyes. In this Unit, let us discuss amines and diazonium salts.
Similar to ammonia, the nitrogen atom of amines is trivalent and it has an unshared pair of electrons. Nitrogen orbitals in amines are therefore, sp3 hybridised and the geometry of amines is pyramidal. Each of the three sp3 hybridised orbitals of nitrogen overlap with orbitals of hydrogen or carbon depending upon the composition of the amines. The fourth orbital of nitrogen in all amines contains an unshared pair of electrons. Because of the presence of unshared pair of electrons, the angle C–N–E, (where E is C or H) is less than 109.5°.
CONTENT
Structure of Amines
Classification
Nomenclature
Preparation of Amines
Physical Properties
Chemical Reactions
Method of Preparation of Diazonium Salts
Physical Properties
Chemical Reactions
Importance of Diazonium Salts in Synthesis of Aromatic Compounds
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