Ibuprofen, (+-)- → Ethyl 2-[4-(2-methylpropyl)phenyl]propanoate

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Reaction Steps

A solution of 2-(4-isobutylphenyl)-propionic acid (Ibuprofen, 9.6 g, 46.5 mmol) and p-toluenesulfonic acid monohydrate (1.52 g, 7.9 mmol) in benzene (100 mL) and ethanol (75 mL) was heated to reflux using a Dean-Stark apparatus for 4 h. The solvent was removed under reduced pressure and the residue was taken up in Et2O (100 mL). The solution was extracted with saturated aqueous NaHCO3 solution (2×100 mL) and water (2×100 mL). The organic layer was dried over anhydrous Na2SO4, filtered and concentrated, affording 204 (10.44 g, 96%) as a clear oil. 1H NMR (CDCl3): δ 7.19 (d, 2 H, J=8.0), 7.08 (d, 2 H, J=8.0), 4.10 (m, 2 H), 3.66 (q, 1 H, J=7.0), 2.44 (d, 2 H, J=7.0), 1.84 (m, 1 H), 1.47 (d, 3 H, J=7.0), 1.19 (t, 3 H, J=7.3), 0.89 (d, 6 H, J=7.0). 13C NMR (CDCl3): δ 174.92, 140.59, 138.07, 129.45, 127.29, 60.79, 45.32, 45.21, 30.35, 22.55, 18.78, 14.29. HRMS (LSIMS, nba): Calcd for C15H23O2 (MH+): 235.1698, found: 235.1688.

Provenance & Evidence