反应详情

温度

-78 °C

122 mg of magnesium shavings were covered with 3 ml of absolute tetrahydrofuran in a sulphonation flask while gassing with argon and, after the addition of a crystal of iodine, treated with a solution of 1.24 g of trans-1-(bromomethyl)-4-pentylcyclohexane in 7 ml of absolute tetrahydrofuran. After completion of the addition the mixture was heated to reflux for a further 30 minutes and then the mixture, cooled to -78° C., was treated in sequence with 0.7 ml of a 0.1N solution of dilithium tetrachlorocuprate in tetrahydrofuran and with a solution of 670 mg of 4,4'-bis(bromomethyl)biphenyl in 10 ml of absolute tetrahydrofuran. The yellow colouration which initially appeared disappeared again after a few minutes. The mixture, warmed to -15° C., was subsequently stirred for a further 17 hours, then treated with 25 ml of 2N hydrochloric acid and extracted three times with 50 ml of diethyl ether each time. The organic phases were washed with 50 ml of saturated sodium chloride solution, dried over magnesium sulphate and concenrated. Low-pressure chromatography (0.5 bar) of the residue (1.06 g) on silica gel with hexane and subsequently hexane/diethyl ether (19:1) as the eluant gave in succession 1,1'-ethylene-bis(trans-4-pentylcyclohexane), 228 mg (22%) of 4,4'-bis[2-(trans-4-pentylcyclohexyl)ethyl]biphenyl, 78 mg (9%) of 4-(bromomethyl)-4'-[2-(trans-4-pentylcyclohexyl)ethyl]biphenyl and 4,4'-bis(bromomethyl)biphenyl. A single crystallization of the 228 mg of 4,4'-bis[2-(trans-4-pentylcyclohexyl)ethyl]biphenyl from hexane yielded 194 mg of colourless needles of clearing point >300° C. (further phase transitions at 68° C., 84° C., 161° C., 203° C., 221° C. and 224° C.). Rf values (hexane): 4,4,-bis(bromomethyl)biphenyl 0.14; 4-(bromomethyl)-4'-[2-(trans-4-pentylcyclohexyl)ethyl]biphenyl 0.24; 4,4'-bis[2-(trans-4-pentylcyclohexyl)ethyl]biphenyl 0.40.

1. additionAfter completion of the addition the mixture
2. temperaturewas heated
3. temperatureto reflux for a further 30 minutes
4. waitThe yellow colouration which initially appeared disappeared again after a few minutes
5. temperatureThe mixture, warmed to -15° C.
6. extractionextracted three times with 50 ml of diethyl ether each time
7. washThe organic phases were washed with 50 ml of saturated sodium chloride solution
8. dry with materialdried over magnesium sulphate