�Structural
unit
Frequency, cm-1
�Stretching vibrations (carbonyl groups)
�Aldehydes and ketones
1710-1750
�Carboxylic acids
1700-1725
�Acid anhydrides
1800-1850
and 1740-1790
�Esters
1730-1750
�Amides
1680-1700
Table 13.4 (p 519)
Infrared Absorption Frequencies