反应详情

温度

40 °C

In 10 g of ethyl acetate were suspended 2.0 g of 2,4,5-trimethoxybenzoic acid (1a) and 1.45 g of NaBr in a stream of argon, to which 4.0 g of BF3.Et2O was then added dropwise at 25° C., followed by heat stirring at 40° C. for 3 hours. The reaction mixture was cooled with ice, to which 10 mL of water was then added dropwise at 10° C., followed by dropwise adding 7.5 g of a 25% (w/w) sodium hydroxide aqueous solution. Thereto was further added 10 mL of water before stirring, followed by filtering off insoluble inorganic matter. To the separated aqueous layer was dropwise added 3.94 g of 35% hydrochloric acid, followed by stirring for 10 minutes. The precipitated crystal was collected by filtration and washed with water. The resultant crystal was then dried under reduced pressure at 60° C. to provide 1.7 g of 2-hydroxy-4,5-dimethoxybenzoic acid (2a) at a yield of 91%.

1. temperatureby heat
2. additionwas then added dropwise at 10° C.
3. stirringbefore stirring
4. filtrationby filtering off insoluble inorganic matter
5. stirringby stirring for 10 minutes
6. filtrationThe precipitated crystal was collected by filtration
7. washwashed with water
8. customThe resultant crystal was then dried under reduced pressure at 60° C.