Method for preparing biphenyl-like monomer liquid crystal using cross-coupling reaction

Abstract

The invention relates to a way to prepare biphenyl metamer mesophase through crossed coupling reaction. The representative structure formula is (I) of which n stands for 1 or 2, R1 stands for C1-C10 linear chain alkane, R2 stands for F or C1-C10 linear chain alkane or OCF3, A stands for cyclohexyl or phenyl, X,Y,Z,W stands for F or H atom, at least one of X and Y is F atom. The method in the invention adopts (II) as the material and palladium as the catalyst, (II) and (III) react to produce different kinds of biphenyl metamer mesophase; the reaction is crossed coupling reaction. The inventionhas simple procedures, mild reacting conditions, low cost and environment-friendly, it's especially applicable to the production of 4-(4'-aldl cyclohexyl) biphenyl metamer mesophase whose benzene ring contains fluoric.

Description

technical field The invention relates to a method for preparing biphenyl monomer liquid crystals, in particular to a method for preparing biphenyl monomer liquid crystals by cross-coupling reaction, and belongs to the technical field of preparation methods of monomer liquid crystals. Background technique 4-(4'-alkylcyclohexyl) biphenyl monomer liquid crystals generally have a low melting point, high clearing point and low viscosity, and at the same time, have good compatibility with other monomer liquid crystals. Therefore, there are a large number of applications in STN liquid crystal display. In 1983, Merck's patent US4545922 disclosed a method for preparing liquid crystals containing fluorine-containing biphenyl monomers: There are many shortcomings in this synthetic route: 1. The nitration and diazotization reactions on the benzene ring will have a large number of side reactions, which directly lead to low product yields; 2. The nitrification and diazotization re...

AI Technical Summary

Problems solved by technology

1. The nitration and diazotization reactions on the benzene ring will have a large number of side reactions, which directly lead to low product yields;

2. The nitrification and diazotization reactions will discharge a large amount of waste acid and waste gas, which will pollute the environment;

3. The synthesis route is unreasonable. The synthesis route of producing products by nitration and diazotization of raw materials will lead to extremely high production costs

Although this synthetic route avoids many by-products such as direct nitration and diazotization, and highly polluting reactions, the strong base BuLi used in the ionization of benzene ring metals is extremely flammable and explosive, and the reaction temperature of -70 ° C is not suitable for industrial production. hard to reach

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