反应详情

温度

-10 °C

A solution of 24.0 g of tetrabromomethane in 100 ml of methylene chloride was placed at -15° C. in a sulphonation flask under argon gasification and treated within 10 minutes with a solution of 38.0 of triphenylphosphine in 50 ml of methylene chloride. The clear orange solution was stirred at -10° C. for a further 10 minutes and subsequently a solution of 5.0 g of trans-4-cyanocyclohexanecarboxaldehyde in 20 ml of methylene chloride was added dropwise thereto at -5° C. within 10 minutes. The mixture was stirred at 0° C. for a further 30 minutes, then poured into 1 l of 10% ethyl acetate/petroleum ether and freed from precipitated triphenylphosphine oxide by filtration. The concentrated filtrate was again digested with 500 ml of 10% ethyl acetate/petroleum ether, filtered and concentrated. Low-pressure chromatography (0.5 bar) of the residue (14 g) on silica gel with 10% ethyl acetate/petroleum ether gave 11.0 g of trans-4-(2,2-dibromovinyl)cyclohexanecarbonitrile which was still contaminated with triphenylphosphine. A second low-pressure chromatography of this material on silica gel with 3% ethyl acetate/petroleum ether gave 9.04 g (85%) of pure trans-4-(2,2-dibromovinyl)cyclohexanecarbonitrile, m.p. 77.5°-78.5° C.

1. waitat -5° C. within 10 minutes
2. stirringThe mixture was stirred at 0° C. for a further 30 minutes
3. customfrom precipitated triphenylphosphine oxide
4. filtrationby filtration
5. filtrationfiltered
6. concentrationconcentrated