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温度

0 °C

3-Bromothiophene-2-carbaldehyde (28.7 g, 0.15 mol) in ethanol (50 mL) was added in one portion to a solution of hydroxylamine hydrochloride (13.8 g, 0.2 mol), sodium hydroxide (8 g, 0.2 mol) in water (30 mL) and ethanol (100 mL). The mixture was stirred at 0° C. for 2 hours and was kept at 0° C. overnight when a precipitate formed. The mixture was diluted with cold water (600 ml) and the solid was collected by filtration yielding 20.5 g, (67%). The aqueous solution was further extracted with ethyl acetate. The organic solution was washed with brine, dried with magnesium sulfate, filtered and evaporated yielding 6.9 g of additional product as a light yellow solid. The total yield was 27.4 g (89%).

1. waitwas kept at 0° C. overnight
2. customwhen a precipitate formed
3. filtrationthe solid was collected by filtration
4. customyielding 20.5 g, (67%)
5. extractionThe aqueous solution was further extracted with ethyl acetate
6. washThe organic solution was washed with brine
7. dry with materialdried with magnesium sulfate
8. filtrationfiltered
9. customevaporated