反应详情

A suspension of 3,4-dimethoxy-benzoic acid (353.5 g, 1.94 moles) in HCHO (1.7 l, 24.5 moles) was prepared under mechanic stirring, cooled in ice, saturated with gaseous HCl (340 g, 9.32 moles), then gradually brought to 60° C. After one night the temperature was brought to the room values and further HCl (300 mg) was bubbled, then the temperature was brought again to 60° C. for one night. The mixture was brought to small volume, taken up with water (1 l ), neutralised with 28% NH4OH (1.5 l) and kept at cool for 2 hours, then filtered. The filtrate was washed with water up to neutrality, then crystallised from CH3OH (2 l ) and dried under vacuum at 60° C. to give 220 g of the title compound (yield: 58.65%).

1. customwas prepared under mechanic stirring
2. customgradually brought to 60° C
3. customwas bubbled
4. waitthe temperature was brought again to 60° C. for one night
5. temperatureat cool for 2 hours
6. filtrationfiltered
7. washThe filtrate was washed with water up to neutrality
8. customcrystallised from CH3OH (2 l )
9. customdried under vacuum at 60° C.