反应详情

In 40 cm3 of dichloromethane, 1.5 g (0.008 mol) of 2-(4'-propylcyclohexyl)propane-1,3-diol, 1.5 g (0.01 mol) of 3,4-difluorobenzaldehyde (manufactured by Aldrich), and 0.1 g of TsOH were refluxed for 3 hours over a hot water bath fitted with a Dean-Stark trap and the water formed was removed continuously from the reaction system. The reaction solution was washed with water and the dichloromethane was distilled off. The distillation residue was recrystallized from a solvent mixture of acetone and methanol to yield 1.6 g (0.005 mol) of trans-2-(3',4'-difluorophenyl)-5-(trans-4'-propylcyclohexyl)-1,3-dioxane. The phase transition points, measured by DSC, were: ##STR31## wherein C is the crystal phase, N is the nematic phase and I is the isotropic liquid phase.

1. customfitted with a Dean-Stark trap
2. customwas removed continuously from the reaction system
3. washThe reaction solution was washed with water
4. distillationthe dichloromethane was distilled off
5. customThe distillation residue was recrystallized from a solvent mixture of acetone and methanol