Synthesis of 3-isopropylbenzoic acid (Method A):
1. In a dry reaction flask, 1-bromo-3-isopropylbenzene (1.24 g, 6.23 mmol) and anhydrous THF (18 mL) were added.
2. add magnesium filament (0.151 g, 6.23 mmol, 1 eq.) and heat the mixture to 50-60°C until the magnesium is completely dissolved to form Grignard reagent.
3. An excess of solid carbon dioxide (CO2) was added to the reaction system and the reaction was continued for 40 minutes.
4. Upon completion of the reaction, the reaction mixture was acidified with 1 M aqueous hydrochloric acid to pH<3.
5. The products were extracted with dichloromethane (DCM) and the organic phases were combined.
6. The organic phase was dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure to afford the target product 3-isopropylbenzoic acid as a white solid (1.07 g, quantitative yield).
7. The product was characterized by 1H-NMR (CDCl3) δ (ppm) 8.00 (s, 1H), 7.95 (d, 1H), 7.49 (d, 1H), 7.41 (t, 1H), 3.00 (m, 1H), 1.30 (d, 6H).
