Table of Characteristic IR Absorptions
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| wavenumber, cm–1 | bond | functional group |
| 3640–3610 (s, sh) | O–H stretch, free hydroxyl | alcohols, phenols |
| 3500–3200 (s,b) | O–H stretch, H–bonded | alcohols, phenols |
| 3400–3250 (m) | N–H stretch | primary, secondary amines, amides |
| 3300–2500 (m) | O–H stretch | carboxylic acids |
| 3330–3270 (n, s) | –C(triple bond)C–H: C–H stretch | alkynes (terminal) |
| 3100–3000 (s) | C–H stretch | aromatics |
| 3100–3000 (m) | =C–H stretch | alkenes |
| 3000–2850 (m) | C–H stretch | alkanes |
| 2830–2695 (m) | H–C=O: C–H stretch | aldehydes |
| 2260–2210 (v) | C(triple bond)N stretch | nitriles |
| 2260–2100 (w) | –C(triple bond)C– stretch | alkynes |
| 1760–1665 (s | C=O stretch | carbonyls (general) |
| 1760–1690 (s) | C=O stretch | carboxylic acids |
| 1750–1735 (s) | C=O stretch | esters, saturated aliphatic |
| 1740–1720 (s) | C=O stretch | aldehydes, saturated aliphatic |
| 1730–1715 (s) | C=O stretch | alpha,beta–unsaturated esters |
| 1715 (s) | C=O stretch | ketones, saturated aliphatic |
| 1710–1665 (s) | C=O stretch | alpha,beta–unsaturated aldehydes, ketones |
| 1680–1640 (m) | –C=C– stretch | alkenes |
| 1650–1580 (m) | N–H bend | primary amines |
| 1600–1585 (m) | C–C stretch (in–ring) | aromatics |
| 1550–1475 (s) | N–O asymmetric stretch | nitro compounds |
| 1500–1400 (m) | C–C stretch (in–ring) | aromatics |
| 1470–1450 (m) | C–H bend | alkanes |
| 1370–1350 (m) | C–H rock | alkanes |
| 1360–1290 (m) | N–O symmetric stretch | nitro compounds |
| 1335–1250 (s) | C–N stretch | aromatic amines |
| 1320–1000 (s) | C–O stretch | alcohols, carboxylic acids, esters, ethers |
| 1300–1150 (m) | C–H wag (–CH2X) | alkyl halides |
| 1300–1150 (m) | C–H wag (–CH2X) | alkyl halides |
| 1250–1020 (m) | C–N stretch | aliphatic amines |
| 1000–650 (s) | =C–H bend | alkenes |
| 950–910 (m) | O–H bend | carboxylic acids |
| 910–665 (s, b) | N–H wag | primary, secondary amines |
| 900–675 (s) | C–H "oop" | aromatics |
| 850–550 (m) | C–Cl stretch | alkyl halides |
| 725–720 (m) | C–H rock | alkanes |
| 700–610 (b, s) | –C(triple bond)C–H: C–H bend | alkynes |
| 690–515 (m) | C–Br stretch | alkyl halides |
m=medium, w=weak, s=strong, n=narrow, b=broad, sh=sharp