[CH2:1]([O:3][C:4]1[CH:14]=[CH:13][C:7]([C:8]([O:10]CC)=[O:9])=[CH:6][C:5]=1[CH3:15])[CH3:2].[OH-].[Na+].Cl>O.CO>[CH2:1]([O:3][C:4]1[CH:14]=[CH:13][C:7]([C:8]([OH:10])=[O:9])=[CH:6][C:5]=1[CH3:15])[CH3:2]The crude ethyl 4-ethoxy-3-methyl-benzoate was suspended in a solution of NaOH (10.5 g, 263 mmol) in water (50 mL) and methanol (25 mL). The reaction mixture was refluxed for 1 h. The reaction mixture was cooled to 0° C., acidified with 12 M HCl (24.7 mL, 296 mmol) and the resulting solid filtered. The solid was slurried with acetonitrile and filtered to provide 4-ethoxy-3-methyl-benzoic acid (760 mg, 4.22 mmol, 64%) as a light pink solid. ESI-MS m/z calc. 180.07864. found 181.3 (M+1)+; Retention time: 1.31 minutes (3 min run). 1H NMR (400 MHz, DMSO-d6) δ 12.50 (s, 1H), 7.77 (dd, J=8.5, 2.2 Hz, 1H), 7.73 (d, J=1.5 Hz, 1H), 7.00 (d, J=8.6 Hz, 1H), 4.11 (q, J=7.0 Hz, 2H), 2.17 (s, 3H), 1.36 (t, J=7.0 Hz, 3H).
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