| 摘要 |
<p>PURPOSE:To prepare the titled liquid crystal, in high yield, with simplified process, preventing the formation of impurities by side reactions, by protecting the phenolic hydroxyl group of 4-hydroxybenzoic acid with silyl group, removing the protecting group after esterification, and again esterifying the product. CONSTITUTION:4-Hydroxybenzoic acid is reacted with the compound of formula I(R1 and R3 are CH3 or C2H5 and R2 is 4-alkyl-phenyl; or R1 and R2 are 4-alkyl- phenyl and R3 is CH3 or C2H5; or R1-R3 are 4-alkyl-phenyl) to protect the phenolic hydroxyl group, and then subjected to the first-stage esterification reaction. Then the protecting group is removed, and the product is subjected to the second-stage esterification reaction to obtain the objective compound of formula II[R4 and R5 are group of formula III-VI (l, m, n, and p are integers 1-10)].</p> |
