反应详情

7.3 g (0.018 mol) of 2-(4'-bromo-3',5'-difluorophenyl)-5-(4'-propylcyclohexyl)-1,3-dioxane, 2.5 g (0.027 mol) of CuCN2 and 54 cm3 of NMP were refluxed for 2 hours with a mantle heater. After cooling the reactant to room temperature, 40 cm3 of EDA was added, it was poured into 50 cm3 of ice water, extracted with chloroform and washed with an aqueous EDA solution and water. The chloroform was removed, and the residue was dissolved in hexane and washed with water to remove the NMP. The hexane was removed, and the residue was treated in a silica gel column with chloroform as the solvent. The chloroform was removed, and the residue was repeatedly recrystallized in a solvent mixture of acetone and methanol until there were no cis forms to obtain 1.4 g (0.004 mol) of trans-2-(4'-cyano-3',5'-difluorophenyl)-5-(trans-4'-propylcyclohexyl)-1,3-dioxane. The phase transition temperature of this compound was measured with DSC as follows. ##STR17## (here, C shows crystals, N shows the nematic phase and I shows isotropic liquid.)

1. addition40 cm3 of EDA was added
2. extractionextracted with chloroform
3. washwashed with an aqueous EDA solution and water
4. customThe chloroform was removed
5. dissolutionthe residue was dissolved in hexane
6. washwashed with water
7. customto remove the NMP
8. customThe hexane was removed
9. additionthe residue was treated in a silica gel column with chloroform as the solvent
10. customThe chloroform was removed
11. customthe residue was repeatedly recrystallized in a solvent mixture of acetone and methanol until there