反应详情

956 mg of the 4-[2-(p-pentylphenyl)ethenyl]cyclohexanecarbonitrile obtained were dissolved in 50 ml of toluene in a sulphonation flask, treated with 150 mg of palladium/carbon (10%) and hydrogenated at normal pressure and room temperature until the hydrogen uptake came to a standstill (about 30 minutes). Filtration of the mixture (rinsing with toluene), concentration of the filtrate and low-pressure chromatography (0.4 bar) of the residue (890 mg) on silica gel with 5% ethyl acetate/petroleum ether gave 788 mg (82%) of 4-[2-(p-pentylphenyl)ethyl]cyclohexanecarbonitrile as a viscous colourless oil. Although in the thin-layer chromatogram using different solvent systems as the eluant only a single spot appeared, according to gas chromatographic and NMR spectroscopic analysis this material was a cis/trans isomer mixture (about 1:3). Two-fold crystallization of this material from pentane at -20° C. finally yielded trans-4-[2-(p-pentylphenyl)ethyl]cyclohexanecarbonitrile of sufficient purity (according to gas chromatographic analysis 98.8% of trans compound and 1.2% of cis compound); m.p. 22.4° C., cl.p. (N-I) -14.1° C.

1. customcame to a standstill (about 30 minutes)
2. filtrationFiltration of the mixture (rinsing with toluene), concentration of the filtrate and low-pressure chromatography (0.4 bar) of the residue (890 mg) on silica gel with 5% ethyl acetate/petroleum ether