反应详情

To a solution of 2-chloro-5-fluorotoluene (5.0 g) in acetic anhydride (40 ml) was added dropwise under ice-cooling concentrated sulfuric acid (40 ml), and then added dropwise a solution of anhydrous chromic acid (9.3 g) in acetic anhydride (40 ml) for 2 hours. The mixture was stirred at the same temperature for 1 hour, poured into ice-water and extracted with diethylether. The organic layer was washed with sodium carbonate solution, water and saturated brine and dried with magnesium sulfate. Under reduced pressure, the solvent was evaporated, and the residue was dissolved in tetrahydrofuran (10 ml). To the mixture were added water (4 ml) and concentrated sulfuric acid (4 ml), and the mixture was stirred at 100° C. for 30 minutes and cooled. The reaction solution was extracted with ethyl acetate. The organic layer was washed with sodium carbonate solution, water and saturated brine and dried with magnesium sulfate. Under reduced pressure, the solvent was evaporated to give the residue, which was subjected to silica gel column chromatography to give 2-chloro-5-fluorobenzaldehyde (1.6 g).

1. extractionextracted with diethylether
2. washThe organic layer was washed with sodium carbonate solution, water and saturated brine
3. dry with materialdried with magnesium sulfate
4. customUnder reduced pressure, the solvent was evaporated
5. dissolutionthe residue was dissolved in tetrahydrofuran (10 ml)
6. additionTo the mixture were added water (4 ml) and concentrated sulfuric acid (4 ml)
7. stirringthe mixture was stirred at 100° C. for 30 minutes
8. temperaturecooled
9. extractionThe reaction solution was extracted with ethyl acetate
10. washThe organic layer was washed with sodium carbonate solution, water and saturated brine
11. dry with materialdried with magnesium sulfate
12. customUnder reduced pressure, the solvent was evaporated
13. customto give the residue, which