摘要:
Disclosed herein is a novel process for preparing 3-hydroxyesters, comprising: (a) reacting an epoxide derivative with carbon monoxide and alcohol in a solvent at a temperature of 30˜150° C. under a pressure of 50˜3000 psig by using a catalyst system consisting of a catalytic amount of a cobalt compound and optionally an effective amount of a promoter to produce a 3-hydroxyester or a derivative thereof; (b) separating the resulting product and the solvent from the cobalt compound and the promoter in a stripping column at a temperature of −30˜200° C. in an atmosphere of a stabilizing gas; and (c) recycling a part or all of the separated cobalt compound and promoter to the step (a) and repeating the steps (a) through (c).
摘要:
A vertical alignment liquid crystalline compound containing a laterally substituted aromatic cyclic moiety. The liquid crystalline compound has a wide temperature range of the nematic phase, a high optical anisotropy and a high negative dielectric anisotropy. In addition, since the rotation viscosity and the K33/K11 ratio of the liquid crystalline compound are maintained at a low level, the liquid crystalline compound can be effectively used as a liquid crystalline medium having good image quality and a high response speed even when applied to thin liquid crystalline cells.