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Learn about the structure and classification of amines, including aliphatic, aromatic, heterocyclic, and heterocyclic aliphatic and aromatic amines. Discover the IUPAC nomenclature for aliphatic amines and explore the physical properties, boiling points, and odor of different amines. Understand the basicity of amines and their role in the formation of ammonium salts, alkaloids, and nitrosation.
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Chemistry 2100 Chapter 16
Amines • Amines are nitrogen-containing compounds
Structure and Classification Amines are classified as 1°, 2°, or 3° depending on the number of carbon groups bonded to nitrogen. Aliphatic amine: All carbons bonded to nitrogen are derived from alkyl groups. See the three above. Aromatic amine: One or more of the groups bonded to nitrogen are aryl groups.
Structure and Classification • Heterocyclic amine: An amine in which the nitrogen atom is part of a ring. • Heterocyclic aliphatic amine: A heterocyclic amine in which the ring is saturated (has no C=C bonds). • Heterocyclic aromatic amine: The amine nitrogen is part of an aromatic ring.
Nomenclature IUPAC names • We derive IUPAC names for aliphatic amines just as we did for alcohols. • Drop the final -e of the parent alkane and replace it by -amine. • Use a number to locate the amino group on the parent chain.
Physical Properties Amines are polar compounds: • Both 1° and 2° amines have N-H bonds, and can form hydrogen bonds with one another. • 3° Amines have no N-H bond and cannot form hydrogen bonds with one another.
Boiling Points NH3 (bp -33°C)H2O (bp +100°C) CH3CH3 (bp -88°C) CH3NH2 (bp -7°C) CH3OH (bp +65°C) CH3CH2CH2NH2 (bp 48°C) CH3CH2NHCH3 (bp 35°C) (CH3)3N (bp 3°C)
Odor Like ammonia, low-molecular-weight amines have very sharp, penetrating odors. • Trimethylamine, for example, is the pungent principle in the smell of rotting fish. • Two other particularly pungent amines are 1,4-butanediamine (putrescine) and 1,5-pentanediamine (cadaverine).
Ammonium Salts free base ammonium salt (hydrochloride)
Alkaloids (S)-(–)-nicotine (S)-(+)-coniine (–)-cocaine hydrochloride (–)-strychnine
Orange II American Flag Red
Morphine Codeine Heroin