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温度

0 °C

A solution of 16.6 g of tetrabromomethane in 230 ml of methylene chloride was placed at 0° C. in a sulphonation flask under an argon atmosphere and treated portionwise within 10 minutes with 26.2 g of solid triphenylphosphine; there thereby resulted a clear, deep orange solution. After completion of the addition, the mixture was stirred at 0° C. for a further 5 minutes and then a solution of 6.46 g of p-(trans-4-pentylcyclohexyl)benzaldehyde in 20 ml of methylene chloride was added dropwise within 10 minutes. After stirring at 0° C. for a further 1 hour, the orange mixture was poured into 750 ml of hexane and the precipitate which thereby separated was filtered off (rinsing with hexane). The concentrated filtrate (20.4 g) was digested with 250 ml of warm hexane, filtered (rinsing with warm hexane) and the filtrate was concentrated. Low-pressure chromatography (0.5 bar) of the residual oil (9.70 g) on silica gel with 3% ethyl acetate/petroleum ether gave 8.08 g (78%) of β,β-dibromo-p-(trans-4-pentylcyclohexyl)styrene as colourless crystals (purity 97.5%); m.p. 48° C.

1. customthere thereby resulted a clear, deep orange solution
2. additionAfter completion of the addition
3. stirringAfter stirring at 0° C. for a further 1 hour
4. customthe precipitate which thereby separated
5. filtrationwas filtered off
6. wash(rinsing with hexane)
7. filtrationfiltered
8. wash(rinsing with warm hexane)
9. concentrationthe filtrate was concentrated