Final answer:
The IR absorption ranges are around 1620-1680 cm¹ for C=C, 1650-1750 cm¹ for C=O with key peaks at 1716 cm¹ for ketones, and 1600-1690 cm¹ for C=N, which allows for the identification of these groups using infrared spectroscopy.
Step-by-step explanation:
The IR absorption range for various double bonds is specific to the type of double bond present in the molecule. For example, the carbon-carbon double bond (C=C) typically absorbs in the range of around 1620-1680 cm¹, which is characteristic for alkenes. The carbon-oxygen double bond (C=O), known as a carbonyl group, is highly polar and has a strong absorption, usually in the range of 1650-1750 cm¹, with key peaks around 1716 cm¹ for ketones. This strong peak indicates a powerful dipole change when the bond stretches, making it very noticeable in an infrared spectrum.
The carbon-nitrogen double bond (C=N) is less common and has a variable absorption range, but often appears in the region of 1600-1690 cm¹ depending on the surrounding chemical environment. Infrared spectroscopy is a valuable technique for identifying functional groups within organic compounds based on their characteristic absorption frequencies, and the Spectral Database for Organic Compounds can provide more examples of IR spectra.