反应详情

2-carboxybenzenepropanoic acid (9.7 g., 0.05 mole), acetic anhydride (15.5 g., 0.15 mole) and acetyl chloride (0.5 g) in dichloromethane (200 ml) was boiled at reflux under nitrogen for 16 hr. The solvents were removed at high vacuum and the residual cyclic anhydride was heated at reflux with methanol (250 ml) for 2 hrs. Evaporation of solvent gave the sub-title compound as an oil which crystallised with petroleum ether (b.p. 60°-80°) to a solid (6.3 g) mp 76°-79°. This was further purified by continuous extraction of the crude product with boiling petroleum (b.p. 40°-60°) in a Soxhlet apparatus. The pure compound, mp 79°-81° separated from the extracts on cooling.

1. temperatureat reflux under nitrogen for 16 hr
2. customThe solvents were removed at high vacuum
3. temperaturethe residual cyclic anhydride was heated
4. temperatureat reflux with methanol (250 ml) for 2 hrs
5. customEvaporation of solvent