Functional groups are structural units within organic compounds defined by specific atom and bond arrangements. Infrared is a powerful identification tool for functional groups because of the similar absorption frequencies for those groups in different molecules. The actual frequency is affected by the environment, so the reference chart shows wide bands rather than specific frequencies. The identification of functional groups is a cornerstone of IR spectroscopy and organic chemistry.
To help make your job easier, we outlined the basic organic functional groups, their positions of infrared bans, their relative peak intensities, and their functional group representation. Download this easy-to-read chart.