Classification of Amines
NCERT Reference: Chapter 9 – Amines – Page 241
Quick Notes
- Amines are classified as primary (1°), secondary (2°), or tertiary (3°).
- This depends on how many hydrogen atoms of NH3 are replaced by carbon groups.
- Simple amines have identical groups and mixed amines have different substituents.
- Amines may also be classified as aliphatic, aromatic, or aralkyl depending on the nature of the groups attached.
Full Notes:
Amines are classified based on the number of hydrogen atoms in ammonia (NH3) that are replaced by alkyl or aryl groups.
| Type | General Formula | Description |
|---|---|---|
| Primary (1°) | R–NH2 | One alkyl/aryl group attached to nitrogen and two H atoms remain. |
| Secondary (2°) | R2NH or R–NHR′ | Two alkyl/aryl groups and one hydrogen attached to nitrogen. |
| Tertiary (3°) | R3N or R2NR′ | Three alkyl/aryl groups attached to nitrogen and no hydrogen on nitrogen. |
If all the groups are the same = a simple amine
If the groups are different = a mixed amine
Examples:
- Primary: CH3NH2 (methylamine), C6H5NH2 (aniline)
- Secondary: (CH3)2NH (dimethylamine)
- Tertiary: (CH3)3N (trimethylamine)
Based on Nature of Carbon Groups
| Type | Definition | Example |
|---|---|---|
| Aliphatic amines | Nitrogen bonded only to alkyl groups. | CH3NH2 (methylamine) |
| Aromatic amines | Nitrogen bonded directly to aryl group. | C6H5NH2 (aniline) |
| Aralkyl amines | Alkyl group with aryl attached, but nitrogen not directly on ring. | C6H5CH2NH2 (benzylamine) |
Summary
- Amines are grouped by how many hydrogens of ammonia are replaced.
- Primary, secondary and tertiary amines differ in the number of carbon groups on nitrogen.
- Simple amines have identical groups and mixed have different groups.
- Aliphatic, aromatic and aralkyl classes depend on the attached carbon framework.