反应详情

温度

55 °C

Under a dry nitrogen atmosphere, approximately 3 g of aluminum shot was added to 225 ml of dibromomethane. The temperature was raised to 35°-40° C., and hydrogen bromide gas was bubbled into the mixture. After 1 hour a reaction began to occur, and, with the temperature being maintained at 35°-40° C., a second and third portion of aluminum shot (total of 9.67 g, 0.358 mole) was added to the mixture. After complete addition, the reaction mixture was heated at 55° C. for 1 hour. The hydrogen bromide gas flow was stopped, and the reaction mixture was cooled to approximately 6° C. Cis-3-(2,2-dichloroethenyl)-2,2-dimethylcyclopropanecarboxylic acid (50.0 g, 0.239 mole) in 150 ml of dibromomethane was added to the cooled reaction mixture during 1 hour. After complete addition, the reaction mixture was stirred for 30 minutes. A nitrogen inlet was placed in the reaction mixture, and nitrogen was pulled through the mixture for 90 minutes by applying a slight vacuum to the reaction pot. Distilled water was added dropwise, and the resulting mixture was allowed to stand at room temperature for approximately 18 hours. The organic phase was separated, and the aqueous phase was extracted with 600 ml and 200 ml portions of diethyl ether. The ether washes were combined with the organic phase, and the whole was washed once with a 1 N hydrochloric acid solution and one with a saturated aqueous solution of sodium chloride. The organic phase was dried with magnesium sulfate, filtered, and the filtrate was concentrated under reduced pressure to give a solid. The solid was dried under a vacuum for 18 hours, then was crystallized twice from n-heptane and sublimed to give (+)-cis-3-(2,2-dibromoethenyl)-2,2-dimethylcyclopropanecarboxylic acid, m.p. 109°-111° C.

1. temperatureThe temperature was raised to 35°-40° C.
2. customhydrogen bromide gas was bubbled into the mixture
3. temperaturewith the temperature being maintained at 35°-40° C.
4. additionwas added to the mixture
5. additionAfter complete addition
6. temperaturethe reaction mixture was cooled to approximately 6° C
7. additionAfter complete addition
8. customA nitrogen inlet was placed in the reaction mixture, and nitrogen
9. waitwas pulled through the mixture for 90 minutes
10. waitto stand at room temperature for approximately 18 hours
11. customThe organic phase was separated
12. extractionthe aqueous phase was extracted with 600 ml and 200 ml portions of diethyl ether
13. washthe whole was washed once with a 1 N hydrochloric acid solution and one with a saturated aqueous solution of sodium chloride
14. dry with materialThe organic phase was dried with magnesium sulfate
15. filtrationfiltered
16. concentrationthe filtrate was concentrated under reduced pressure
17. customto give a solid
18. customThe solid was dried under a vacuum for 18 hours
19. customwas crystallized twice from n-heptane