Important IR Stretches
sp³ C-H (alkanes)
<3000
sp² C-H
>3000
C (triple bond) C
2100-2260
C (triple bond) N
2220-2260
N-H
3300
sp C-H
3300
O-H (alcohol)
3300 (st, broad)
O-H (carboxylic acid)
3300 - 2700 (covers up about 1/3 of the graph)
Aldehyde C-H
*2700-2850* (doesn't need to be double peaked like in the picture)
C-O (generic)
1050
C-O-C (ester)
1250 & 1050 (st, broad)
CH₃ umbrella
1385
Geminal dimethyl (a carbon attached to two methyl groups)
1385 (doublet)
C=C (conjugated)
1620-1640
C=C (isolated)
1640-1680
C=O (amide)
1640-1700
C=O (ketone/acid)
1700-1725
Benzene
1700-2000 (wiggle waggle)
C=O (aldehyde)
1720-1740
C=O (ester)
1730-1750
C=O (acid halide/anhydride)
1760-1860
C=C (aromatic)
around 1600