Method for synthesizing diaryl acetylene monomer liquid crystal

Abstract

The invention discloses a method for synthesizing a diaryl acetylene monomer liquid crystal, which comprises a method for performing coupling reaction between halogenated aryl hydrocarbon and aryl alkyne, wherein the reaction conditions comprise that the halogenated aryl hydrocarbon and the aryl alkyne perform the coupling reaction in an acetone / water (5:2) solvent at a temperature of between 50 and 110 DEG C, under the normal pressure and under the protection of inert gas, and a catalyst used in the reaction is Pd / C-CuI-PPh3. The halogenated aryl hydrocarbon and the aryl alkyne are added according to an equivalent weight of 1 / 1.1, three substances in the catalyst Pd / C-CuI-PPh3 are added according to the equivalent weight of (0.0003-0.007) / (0.006-0.05) / (0.005-0.007), and preferentially, the molar percentage of the three substances relative to the halogenated aryl hydrocarbon or the aryl alkyne is 0.03 / 0.6 / 0.6. The method can also perform catalytic reaction by using a mother liquor of the filtered product and other solid matters of the coupling reaction to prepare the diaryl acetylene monomer liquid crystal continuously. The method provides a novel catalytic reaction system for synthesizing a diaryl phenylacetylene monomer liquid crystal, the catalyst is cheap and easy to obtain and can be used repeatedly, the separation and purification processes of the liquid crystal product are simple, the products after the reaction are directly filtered out, and the obtained monomer liquid crystal has stable quality and high yield and can greatly reduce the production cost and reduce the waste emission.

Description

technical field [0001] The invention relates to a production method of liquid crystal materials, in particular to a catalytic method for synthesizing liquid crystals of diaryl acetylene monomers. The invention belongs to the technical field of catalytic synthesis chemical industry. Background technique [0002] In order to meet the corresponding characteristics required by various liquid crystal display devices, it is usually necessary to mix and use about 20 kinds of liquid crystal compounds with different properties. According to the use requirements of the display device, the liquid crystal composition should have a suitable optical anisotropy (Δn). In order to shorten the response time of the liquid crystal composition and reduce energy consumption, it is necessary to reduce the driving voltage of the liquid crystal display. In order to achieve a lower driving voltage, the need to increase the dielectric anisotropy Δε. At the same time, in order to meet the fast photoe...

AI Technical Summary

Problems solved by technology

This traditional homogeneous catalytic reaction system has the following significant disadvantages: since the palladium homogeneous catalyst containing phosphine ligands is mainly used in the current production process, it is difficult to recycle the precious metal catalyst with the product separation in actual production, which not only increases It increases the production cost, causes a lot of waste, and pollutes the environment; in this type of reaction process, different impurity by-products are often produced, and the product purification process is complicated, which brings difficulties to the purification of monomer liquid crystals

There is no report using Pd / C as catalyst in the synthesis of diaryleacetylene monomer liquid crystal

[0004] In addition, Pd(O) and Pd(II) homogeneous catalysts are used in the known related monomer liquid crystal synthesis technology, and the yield of monomer liquid crystal is between 60% and 80%, and due to the presence of the catalyst, the The purification of the product becomes complicated, such as: Chinese patent ZL 200510088782.X, patent application ZL 200610140460.X, ZL 200510090280.0, ZL 200510090279.8 all use Pd(O) and Pd(II) homogeneous catalysts

[0005] As a liquid crystal material for display, the purity of monomer liquid crystals is high, but most of the reported synthesis processes of diarylphenylacetylene monomer liquid crystals use homogeneous catalysts, which brings difficulties for subsequent purification work. very difficult

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