The general procedure for the synthesis of 2-(4-formylphenyl)acetic acid from 4-(bromomethyl)phenylacetic acid was as follows:
1. Preparation of Intermediate 4: To a mixed solution of 2-[4-(bromomethyl)phenyl]acetic acid (770 mg, 3.36 mmol) in ethanol (6 mL) and water (6 mL) was added hexamethylenetetramine (1.26 g, 9.0 mmol).
2. The reaction mixture was heated to reflux for 4 hours.
3. Concentrated hydrochloric acid (1.5 mL) was slowly added to the mixture under reflux.
4. Continue heating and refluxing for 30 minutes, then cool to room temperature.
5. Water (20 mL) and dichloromethane (20 mL) were added, and the organic phase was separated and filtered through hydrophobic filter paper.
6. The solvent was removed by vacuum to afford the title compound 2-(4-formylphenyl)acetic acid as an off-white solid (479 mg, 87% yield). 7. The product was analyzed by 1H NMR.
7. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 10.01 (s, 1H), 7.86 (d, J = 7.9 Hz, 2H), 7.47 (d, J = 7.9 Hz, 2H), 3.75 (s, 2H).
