Potassium Carbonate → 3-(4-Bromothiophenoxy)propionic acid

To a solution of 1.44 g (35.7 mmol) of NaOH in 20.0 ml degassed H2O (sparged with argon) was added 6.79 g (35.7 mmol) of 4-bromothiophenol. The resulting mixture was stirred at room temperature for 30 minutes. A second flask was charged with 2.26 g (16.3 mmol) of K2CO3 and 15 ml of degassed H2O. To this solution was added (in portions) 5.00 g (32.7 mmol) of 3-bromopropionic acid. The resulting potassium carboxylate solution was added to the sodium thiolate solution, and the resulting mixture stirred at room temperature for 48 hours. The mixture was filtered and the filtrate extracted with benzene, and the combined organic layers were dicarded. The aqueous layer was acidified with 10% HCl and extracted with EtOAc. The combined organic layers were washed with saturated aqueous NaCl, dried over MgSO4, and concentrated under reduced pressure. The resulting solid was recrystallized from Et2O -hexanes to give the title compound as off-white crystals. 1H NMR (CDCl3): δ 7.43 (2H, d, J=8.4 Hz), 7.25 (2H, d, J=8.4 Hz), 3.15 (2H, t, J=7.3 Hz), 2.68 (2H, t, J=7.3 Hz).