反应详情

温度

-5 °C

A solution, cooled to -20° C., of 331.6 g of tetrabromomethane in 1 l of dry methylene chloride was treated dropwise under nitrogen gasification within 30 minutes with a solution of 524.6 g of triphenylphosphine in 1 l of methylene chloride. The mixture was subsequently stirred at -5° C. for a further 30 minutes, then treated dropwise at this temperature within 30 minutes with a solution of 91.2 g of trans-4-pentylcyclohexanecarboxaldehyde in 500 ml of methylene chloride and stirred at -5° C. for a further 2 hours. The mixture was poured into 6 l of hexane, the mixture was stirred at -20° C. for 1 hour and then the precipitate was filtered off under suction and washed well with about 1 l of cold (-20° C.) hexane. The filtrate was concentrated to a volume of about 1 l on a rotary evaporator, dilued with 2 l of hexane, again concentrated to a volume of about 1 l and stirred at -20° C. for a further 1 hour. The precipitate was filtered off under suction and rinsed well with about 500 ml of cold (-20° C.) hexane. The filtrate was freed from solvent on a rotary evaporator and the yellow oil obtained was filtered chromatographically on silica gel with about 3 l of hexane. The eluate was evaporated up to constant weight on a rotary evaporator, there being obtained 122.8 g (72.6%) of trans-1-(2,2-dibromovinyl)-4-pentylcyclohexane as a colourless oil; Rf-value (hexane) 0.55.

1. stirringstirred at -5° C. for a further 2 hours
2. stirringthe mixture was stirred at -20° C. for 1 hour
3. filtrationthe precipitate was filtered off under suction
4. washwashed well with about 1 l of cold (-20° C.) hexane
5. concentrationThe filtrate was concentrated to a volume of about 1 l on a rotary evaporator
6. concentrationagain concentrated to a volume of about 1 l
7. stirringstirred at -20° C. for a further 1 hour
8. filtrationThe precipitate was filtered off under suction
9. washrinsed well with about 500 ml of cold (-20° C.) hexane
10. customThe filtrate was freed from solvent on a rotary evaporator
11. customthe yellow oil obtained
12. filtrationwas filtered chromatographically on silica gel with about 3 l of hexane
13. customThe eluate was evaporated up to constant weight on a rotary evaporator, there