A compound C₁₀H₁₂O₂ has a strong IR band near 1720 cm⁻¹, a mass-spectrum peak at m/z 122, and ¹H NMR signals δ 8.1–8.0 (2H,m), 7.6–7.5 (1H,m), 7.5–7.3 (2H,m), 4.3 (2H,t), 1.8 (2H,sextet), 1.0 (3H,t). Identify it.
Five aromatic protons indicate a monosubstituted phenyl ring. A 2H triplet at 4.3 ppm identifies O–CH₂ in an ester, coupled to a middle CH₂ that appears as an approximate sextet; the terminal methyl is a triplet. This is an n-propyl ester. The downfield aromatic pair and conjugated carbonyl identify benzoate, so B, propyl benzoate. The m/z 122 fragment is consistent with loss of propene from its 164 mass parent.
More Experimental Techniques in Organic Chemistry: Optical rotation (polarimetry). Application of various chromatographic techniques such as thin-layer, column, HPLC and GC. Applications of UV-visible, IR, NMR spectroscopy and Mass spectrometry in the structural determination of organic molecules. questions
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