Amines are organic compounds derived from ammonia (NH3NH_3NH3) by replacing one or more hydrogen atoms with alkyl or aryl groups. Depending on the number and nature of the groups attached to the nitrogen atom, amines are classified into different types.
Based on the Number of Alkyl or Aryl Groups Attached to Nitrogen
Amines are classified as primary, secondary, or tertiary depending on the number of alkyl or aryl groups directly attached to the nitrogen atom.
1. Primary (1°) Amines
Primary amines are formed when one hydrogen atom of ammonia is replaced by an alkyl or aryl group. The nitrogen atom remains attached to one carbon group and two hydrogen atoms.
General Formula: RNH2
Examples: CH3NH2 (Methylamine) , C6H5NH2 (Aniline)
2. Secondary (2°) Amines
Secondary amines are formed when two hydrogen atoms of ammonia are replaced by alkyl or aryl groups. The nitrogen atom is attached to two carbon groups and one hydrogen atom.
General Formula: R2NH
Examples: (CH3)2NH (Dimethylamine), C6H5NHCH3 (N-Methylaniline)
3. Tertiary (3°) Amines
Tertiary amines are formed when all three hydrogen atoms of ammonia are replaced by alkyl or aryl groups. The nitrogen atom is attached to three carbon groups and does not contain any hydrogen atom.
General Formula: R3N
Examples: (CH3)3N (Trimethylamine) , (C2H5)3N (Triethylamine)
Based on the Nature of the Hydrocarbon Group
Amines are also classified according to the nature of the hydrocarbon group attached to the nitrogen atom. Depending on whether the nitrogen is bonded to an alkyl group or an aromatic ring, amines are classified as aliphatic or aromatic amines.
1. Aliphatic Amines
Amines in which the nitrogen atom is attached to one or more alkyl groups are called aliphatic amines. These amines may be primary, secondary, or tertiary depending on the number of alkyl groups attached to nitrogen.
Examples: CH3NH2 (Methylamine) , (CH3)2NH (Dimethylamine)
2. Aromatic Amines
Amines in which the nitrogen atom is directly attached to an aromatic ring are called aromatic amines. The aromatic ring influences the properties of the amino group through resonance.
Examples: C6H5NH2 (Aniline) , C6H5NHCH3 (N-Methylaniline)