反应详情

A mixture of 2-methoxy-4-cyanopyridine (57.2 g), semicarbazide hydrochloride (71.24 g), sodium acetate (69.86 g), ethanol (1,200 ml) and water (370 ml) was hydrogenated at 344 kPa using Raney nickel catalyst (1.0 g). The mixture was evaporated to a volume of 450 ml, water (900 ml) was added and the mixture was allowed to stand at 0° overnight. The mixture was filtered and the solid was washed with water and was dissolved in 10% hydrochloric acid (950 ml). Formaldehyde solution (36% w/v, 420 ml) was added and the mixture was warmed for 30 minutes, allowed to cool and was added to a solution of sodium acetate (280 g) in water (840 ml). The mixture was extracted with ether (3×500 ml) and the combined extracts were successively washed with aqueous potassium carbonate and water and were dried out evaporated to give 2-methoxypyridine-4-carboxaldehyde (20.53 g, 35%) m.p. 33-5° . A sample recrystallised from petroleum ether had m.p. 33-36°.

1. customThe mixture was evaporated to a volume of 450 ml, water (900 ml)
2. additionwas added
3. filtrationThe mixture was filtered
4. washthe solid was washed with water
5. dissolutionwas dissolved in 10% hydrochloric acid (950 ml)
6. additionFormaldehyde solution (36% w/v, 420 ml) was added
7. temperaturethe mixture was warmed for 30 minutes
8. temperatureto cool
9. additionwas added to a solution of sodium acetate (280 g) in water (840 ml)
10. extractionThe mixture was extracted with ether (3×500 ml)
11. washthe combined extracts were successively washed with aqueous potassium carbonate and water
12. customwere dried out
13. customevaporated