反应详情

A mixture of 40 g (0.164 mol) of 1,4-dibromo 2,3-butanedione, 60 ml (0.36 M) of triethylorthoformate, and 2 ml of concentrated sulfuric acid was stirred at room temperature for 14 hours, then diluted with 600 ml of chloroform, and washed successively with 100 ml portions of water, 0.5 N hydrochloric acid and saturated sodium chloride solution. The organic solution was dried over anhydrous sodium sulfate filtered, and evaporated leaving an oil. The oil was taken up into 300 ml of hexane and filtered to remove some insoluble material. The hexane filtrate was cooled in a dry-ice/acetone bath, and the resulting precipitate was collected by filtration and dried to give 44 g (84%) of 1,4-dibromo-2,2-diethoxy-3-butanone as a white crystalline solid, mp 40°-41.5°; nmr (CDCl3) (δ): 4.50 (s, 2H); 3.6-3.2 (m, 6H); 1.22 (t, 6H).

1. washwashed successively with 100 ml portions of water, 0.5 N hydrochloric acid and saturated sodium chloride solution
2. dry with materialThe organic solution was dried over anhydrous sodium sulfate
3. filtrationfiltered
4. customevaporated
5. customleaving an oil
6. filtrationfiltered
7. customto remove some insoluble material
8. temperatureThe hexane filtrate was cooled in a dry-ice/acetone bath
9. filtrationthe resulting precipitate was collected by filtration
10. customdried