反应详情

A mixture of 85 g of Raney nickel, which had been washed thoroughly with water, 500 ml of formic acid and 100 g (0.5 mole) of 3-bromo-4-fluoro-benzonitrile was stirred for 24 hours at 90°-100° C. under an atmosphere of a blanketing gas (nitrogen or argon). After cooling to room temperature, 1 liter of water was added and the mixture was extracted twice with 300 ml of toluene. The combined toluene solutions were washed with 200 ml of water, with 200 ml of saturated sodium bicarbonate solution and again with 200 ml of water and then dried by incipient distillation. 1.5 g of air-dried ion exchanger SPC 118, 16 g (0.5 mole) of methanol and 58.5 g (0.55 mole) of orthoformic acid trimethyl ester were then added to the solution, the mixture was stirred for a further 1 hour without a bath and was then warmed at 50° C. for 2 hours. The reaction mixture was cooled, filtered to remove the ion exchanger and washed with 200 ml of 5% strength potassium carbonate solution. The solvent was then stripped off and the residue was distilled in vacuo. 93 g (75% of theory) of 3-bromo-4-fluoro-benzaldehyde dimethyl acetal were obtained in this way, in the form of a colorless liquid with a boiling point of 67°-68° C./0.1 mm Hg.

1. extractionthe mixture was extracted twice with 300 ml of toluene
2. washThe combined toluene solutions were washed with 200 ml of water, with 200 ml of saturated sodium bicarbonate solution and again with 200 ml of water
3. customdried by incipient distillation
4. stirringthe mixture was stirred for a further 1 hour without a bath
5. temperaturewas then warmed at 50° C. for 2 hours
6. temperatureThe reaction mixture was cooled
7. filtrationfiltered
8. customto remove the ion exchanger
9. washwashed with 200 ml of 5% strength potassium carbonate solution
10. distillationthe residue was distilled in vacuo