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Characteristic IR Absorption Frequencies

Functional Group    Type of Vibration       Characteristic Absorptions (cm-1)       Intensity

 Alcohol  

O-H                         (stretch, H-bonded)         3200-3600                                          strong, broad

O-H                         (stretch, free)                   3500-3700                                          strong, sharp   

C-O                         (stretch)                          1050-1150                                           strong

 Alkane  

C-H                         (stretch)                           2850-3000                                          strong

-C-H                        (bending)                         1350-1480                                          variable

Alkene 

=C-H                      (stretch)                          3010-3100                                           medium

=C-H                      (bending)                        675-1000                                             strong

C=C                       (stretch)                          1620-1680                                          variable

Alkyl Halide 

C-F                        (stretch)                          1000-1400                                           strong

C-Cl                       (stretch)                          600-800                                              strong

C-Br                       (stretch)                          500-600                                              strong

C-I                         (stretch)                          500                                                    strong

Alkyne 

C-H                       (stretch)                          3300                                                     strong,sharp

                (stretch)                          2100-2260                                           variable, not

                                                                                                                               present in
                                                                                                                               symmetrical alkynes

Amine 

N-H                       (stretch)                          3300-3500                                           medium(primary
                                                                                                                               amines have two
                                                                                                                               bands; secondary
                                                                                                                               amines have one
                                                                                                                               band, often very
                                                                                                                               weak)

C-N                       (stretch)                           1080-1360                                          medium-weak

N-H                       (bending)                         1600                                                   medium

Aromatic 

C-H                       (stretch)                           3000-3100                                           medium

C=C                      (stretch)                           1400-1600                                          medium-weak,
                                                                                                                              multiple bands

Source:- Silverstein, R.M.; Bassler, G.C.; and Morrill, T.C. Spectrometric Identification of Organic
              Compounds. 4th ed. New York: John Wiley and Sons, 1981. QD272.S6 S55