Amines

Reduction of nitro compounds, Ammonolysis of alkyl halides, Reduction of nitriles, Gabriel synthesis, Hoffmann bromamide reaction

All these methods are valid for preparing amines: (1) Nitro compounds can be reduced using H₂/Ni or Fe/HCl, (2) Alkyl halides react with NH₃ in ammonolysis, (3) Nitriles are reduced with LiAlH₄, (4) Gabriel synthesis uses phthalimide for primary amines, (5) Hoffmann reaction converts amides to amines.

Hydrogen bonds with water

Lower aliphatic amines are soluble in water because the nitrogen atom can form hydrogen bonds with water molecules. The lone pair on nitrogen and the N-H bonds participate in hydrogen bonding with water.

Primary > Secondary > Tertiary

Primary amines have the highest boiling points due to stronger intermolecular hydrogen bonding (two N-H bonds available). Secondary amines have one N-H bond, while tertiary amines cannot form hydrogen bonds, resulting in the order: Primary > Secondary > Tertiary.

Have lone pair of electrons on nitrogen

Amines are basic because they have an unshared pair of electrons on the nitrogen atom. This lone pair can accept protons (H⁺) from acids, making them Lewis bases and Brønsted-Lowry bases.