反应详情

3,4-dimethoxybenzoic-acid (5.0 g, 27 mmol) was added to Formalin (36 ml) saturated with hydrogen chloride gas, and stirred with bubbling hydrogen chloride gas at 65° C. for 2 hrs. The reaction solution was concentrated under reduced pressure, and to the residue was added water (16 ml), followed by neutralizing with dilute aqueous ammonia (concentrated aqueous ammonia:water=2:3). The precipitated crystals were collected by filtration, washed with water, followed by drying to give 4.0 g of 4,5-dimethoxyphthalide.

1. concentrationThe reaction solution was concentrated under reduced pressure
2. additionto the residue was added water (16 ml)
3. filtrationThe precipitated crystals were collected by filtration
4. washwashed with water
5. customby drying