Question 10.6: The IR spectrum of an unknown compound is shown in FIGURE 10...
The IR spectrum of an unknown compound is shown in FIGURE 10.17. What functional groups does the compound contain?
Strategy
All IR spectra have many absorptions, but those useful for identifying specific functional groups are usually found in the region from 1500 cm^{-1} to 3300 cm^{-1} Pay particular attention to the carbonyl region (1670 to 1780 cm^{-1})the aromatic region (1660 to 2000 cm^{-1}), the triple bond region (2000 to 2500cm^{-1})and the C–H region (2500 to 3500 cm^{-1})
The spectrum shows an intense absorption at 1725 cm^{-1} due to a carbonyl group (perhaps an aldehyde, –CHO), a series of weak absorptions from 1800 to 2000 cm^{-1}characteristic of aromatic compounds, and a C–H absorption near 3030 cm^{-1} also characteristic of aromatic compounds. In fact, the compound is phenylacetaldehyde.
