Infrared Absorption Frequencies

Characteristic Infrared Absorption Frequencies

Bond/Compound Type	Frequency Range in cm-1
C-H Alkanes	2850-2960, 1350-1470
C-H Alkenes	3020-3080 (m), 675-1000
C-H Aromatic rings	3000-3100 (m), 675-870
C-H Alkynes	3300
C=C Alkenes	1640-1680 (v)
C≡C Alkynes	2100-2260 (v)
C≈C Aromatic rings	1500, 1600 (v)
	memorize

 

Bond/Compound Type	Frequency Range in cm-1
C-O Alcohols, ethers, carboxylic acids, esters	1080-1300
C=O Aldehydes, ketones, carboxylic acids, esters	1690-1760
O-H Monomeric alcohols, phenols	3610-3640 (v)
O-H Hydrogen-bonded alcohols, phenols	3200-3600 (broad)
O-H Carboxylic acids	2500-3000 (broad)
N-H Amines	3300-3500 (m)
C-N Amines	1180-1360
C≡N Nitriles	2210-2260 (v)
-NO2 Nitro compounds	1515-1560, 1345-1385
	memorize

 

All bands above are strong unless marked otherwise: m=moderate, v=variable.

≈ means mix of single and double bonds.