Preparation method of 4-benzyloxybenzoic acid_Kain Industrial Additive

Background and overview^[1]

4-Benzyloxybenzoic acid is an acid derivative and can be used as a pharmaceutical synthesis intermediate. If 4-benzyloxybenzoic acid is inhaled, move the patient to fresh air; if there is skin contact, take off contaminated clothing, rinse the skin thoroughly with soap and water, and seek medical attention if you feel unwell; if there is eye contact , you should separate your eyelids, rinse with running water or saline, and seek medical attention immediately; if ingested, rinse your mouth immediately, do not induce vomiting, and seek medical attention immediately.

Preparation method^[1]

The preparation of 4-benzyloxybenzoic acid is as follows:

The specific steps are: use a flame-dried screw-capped test tube equipped with a magnetic stirring rod, add phosphine (0.197g, 0.75mmol), KF (0.058g, 1.0mmol) and 18-crown-6 (0.264g, 1.0 Millimoles). The screw cap tube was then evacuated and backfilled with argon. The mixture was dissolved in THF (4.0 mL) under an argon atmosphere at room temperature, and the reaction mixture was cooled to 0 °C and kept stirring for 5 min. Add aromatic hydrocarbon to the stirred solution. Add precursor 2a (1.0 mmol), continue stirring for another 5 min, then add water (0.010 g, 10.0 μL, 0.55 mmol).

The reaction mixture was then stirred at 0°C for 30 minutes. Then 4-bromobenzaldehyde (0.25 mmol) was added, followed by Cs2CO3 (0.326 g, 1.0 mmol) at 0 °C. The reaction mixture was then slowly warmed to room temperature and stirred at 65°C for 24 hours. After 24 h, the reaction was quenched with 3NHCl (0.25 mL) and worked up in CH2Cl2 (3×30 mL). The organic layer was dried over Na₂SO₄ and the solvent was evaporated (230-400°C). The crude residue was purified by silica gel column chromatography (petroleum ether/EtOAc=85/15) to give the corresponding 4-benzyloxybenzoic acid in moderate to good yields.