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13.26 Morphine has a broad, intense band in the 3550-3200 cm⁻¹ region, resulting from the presence of its OH groups. Heroin has bands near 1740 cm⁻¹ due to its ester groups. 13.27 a) The compound is p-methylbenzoic acid. It has a very broad, intense absorption for the OH group centered near 3000 cm⁻¹. Superimposed on this are bands in the 3100-3000 cm⁻¹ region due to H's on sp²-hybridized C's and bands in the 3000-2850 cm⁻¹ region due to H's on sp³-hybridized C's. There is also a intense C=O band in the 1690-1670 cm⁻¹ region. Bands for the aromatic ring appear in the 1600-1450 and 900-675 cm⁻¹ regions. b) The compound is 4-pentyn-2-ol. It has a broad, intense peak in the 3550-3200 cm⁻¹ region due to the OH group. It also has a sharp peak near 3300 cm⁻¹ due to the =C-H group. It also has bands in the 3000-2850 cm⁻¹ region due to H's on sp³-hybridized C's. The band for the C group appears in the 2150-2100 cm⁻¹ region. 13.28 The compound at the left is an ester and is expected to have a carbonyl peak near 1740 cm⁻¹. The compound at the right is a ketone and is expected to have a carbonyl peak near 1715 cm⁻¹. 13.29 The intense peaks near 1520 and 1350 cm⁻¹ result from the presence of a nitro group (NO₂). Nitrobenzene, the compound at the right, is expected to exhibit these peaks. Review of Mastery Goals After completing this chapter you should be able to: Predict the important absorption bands in the IR spectrum of a compound. (Problems 13.5, 13.8, 13.9, 13.10, 13.11, 13.13, 13.15, 13.26, 13.28, and 13.29) Determine the functional group that is present in a compound by examination of its infrared spectrum. (Problems 13.12, 13.14, 13.16, 13.17, 13.18, 13.19, 13.20, 13.21, 13.22, 13.23, 13.24, and 13.25) 211