反应详情

A solution of 84 g of bromine in 75 ml of CCl4 was added dropwise to a mixture of 42 g of NaHCO3 and 56 g of 5-methyl-3-hexen-2-one in 175 ml of CCl4 at 0° C. while stirring in the course of 2 hours. The reaction mixture was stirred for a further hour at 0° C. and then filtered off and evaporated down. The residue was taken up in 150 ml of a 1:1 mixture of ethanol and water, to which 63 g of NaHCO3 had been added. The mixture was heated to reflux while stirring for 2 hours. After cooling, it was poured out into ice-water. This mixture was extracted three times with pentane. This extract was washed twice with water, dried over MgSO4, filtered off and evaporated down. The residue was distilled, 41 g of 3-bromo-5-methyl-3-hexen-2-one (E) being obtained, b.p. 62°-82° C./2 kPa.

1. stirringThe reaction mixture was stirred for a further hour at 0° C.
2. filtrationfiltered off
3. customevaporated down
4. additionThe residue was taken up in 150 ml of a 1:1 mixture of ethanol and water, to which 63 g of NaHCO3
5. additionhad been added
6. temperatureThe mixture was heated
7. temperatureto reflux
8. stirringwhile stirring for 2 hours
9. temperatureAfter cooling
10. additionit was poured out into ice-water
11. extractionThis mixture was extracted three times with pentane
12. washThis extract was washed twice with water
13. dry with materialdried over MgSO4
14. filtrationfiltered off
15. customevaporated down
16. distillationThe residue was distilled