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Infrared Absorption Frequencies

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Updated 2009-02-15 23:13

Characteristic Infrared Absorption Frequencies

Bond/Compound TypeFrequency Range in cm-1
C-H Alkanes2850-2960, 1350-1470
C-H Alkenes3020-3080 (m), 675-1000
C-H Aromatic rings3000-3100 (m), 675-870
C-H Alkynes3300
C=C Alkenes1640-1680 (v)
C≡C Alkynes2100-2260 (v)
C≈C Aromatic rings1500, 1600 (v)
memorize

 

Bond/Compound TypeFrequency Range in cm-1
C-O Alcohols, ethers, carboxylic acids, esters 1080-1300
C=O Aldehydes, ketones, carboxylic acids, esters1690-1760
O-H Monomeric alcohols, phenols3610-3640 (v)
O-H Hydrogen-bonded alcohols, phenols3200-3600 (broad)
O-H Carboxylic acids2500-3000 (broad)
N-H Amines3300-3500 (m)
C-N Amines1180-1360
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.

 

Reference: R. T. Morrison and R. N. Boyd "Organic Chemistry" 6th Edition, Prentice-Hall, Englewood Cliffs, New Jersey, 1992 (ISBN=0-13-643669-2).