- Department of Chemistry and Biochemistry
- Research
- Analytical Lab
- FT-IR Spectroscopy
- IR Absorption Frequencies
Typical IR Absorption Frequencies For Common Functional Groups
| Bond | Functional Group | Frequency in cm−1 (Intensity*) |
|---|---|---|
| C–H | Alkane | 3000–2850 (s) |
| –CH3 | 1450 and 1375 (m) | |
| –CH2− | 1465 (m) | |
| Alkene | 3100–3000 (m), 1000–650 (s) | |
| Aromatic | 3100–3050 (s), 900–690 (s) | |
| Alkyne (terminal) | 3300 (s) | |
| Aldehyde | 2850 and 2750 (w) | |
| C=C | Alkene | 1630 (w‐m) |
| Aromatic | 1600–1475 (w‐m) | |
| C–C | Alkyne | 2150–2100 (w‐m) |
| C=O | Aldehyde | 1740–1720 (s) |
| Ketone | 1725–1705 (s) | |
| Carboxylic Acid | 1730–1700 (s) | |
| Ester | 1750–1730 (s) | |
| Amide | 1670–1640 (s) | |
| Anhydride | 1810 and 1760 (s) | |
| Acid Chloride | 1800 (s) | |
| C–O | Alcohol, Ether, Ester, Carboxylic Acid, Anhydride | 1300–1000 (s) |
| O–H | Alcohol, Phenol | |
| Free | 3650–3600 (m) | |
| Hydrogen‐bonded | 3500–3200 (m) | |
| Carboxylic Acids | 3300–2400 (m) | |
| N–H | Primary and Secondary Amine and Amide | 3550–3060 (m‐s); 1640–1550 (m‐s) |
| C–N | Amine | 1250–1000 (m‐s) |
| C=N | Imine and Oxime | 1690–1640 (w‐s) |
| C=N | Nitrile | 2260–2240 (m) |
| N=O | Nitro (R–NO2) | 1550 and 1350 (s) |
| C–Cl | Chloride | 800–600 (s) |
s = strong; m = medium; w = weak
Contact us
Taesam Kim
Department of Chemistry and Biochemistry
Faraday Hall, Room 319
DeKalb, IL 60115
