Method for synthesizing fluorine-containing antiform alkyl cyclohexyl biphenyl single liquid crystal

Abstract

The invention discloses a method for synthesizing fluorine-containing antiform alkyl cyclohexyl biphenyl single liquid crystal; in the method, bromobenzene and magnesium are selected to carry out Grignard reaction; then the reactants are coupled and hydrolyzed with alkyl cyclohexanone; dehydration, hydrogenation, transformation and iodization are carried out to synthesize alkyl cyclohexyl iodide;the Grignard reaction is carried out on fluorobromobenzene and magnesium, then low temperature coupling is carried out to synthesize p-fluoropheyl boric acid; finally, coupling reaction is carried outto synthesize the target compound; the method of the invention has the characteristics of use of highly active load catalyst, high yield, low production cost, little discharge of three wastes, reduction of generation of isomers and improvement of selectivity and yield of the target compound.

Description

Technical field [0001] The invention belongs to the technical field of fine chemicals, and particularly relates to a method for synthesizing fluorine-containing trans-alkylcyclohexyl biphenyl liquid crystal monomers. Background technique [0002] With the rapid development of super-twisted nematic liquid crystal (STN-LCD) and thin-film transistor array-driven liquid crystal display (TFT-LCD) technologies, in recent years, the two have greatly occupied the high-end display market such as desktop displays and portable notebook computers. Among them, TFT -LCD uses thin-film transistor arrays to directly drive liquid crystal molecules, eliminating the cross-distortion effect, so the display information capacity is large. At this time, it is necessary to use a low-viscosity liquid crystal material to greatly increase the response speed, thereby meeting the needs of video image display. Fluorine-containing trans-cyclohexyl biphenyl 4-(4-alkylcyclohexyl)-4'-fluoro-1,1'-biphenyl liquid ...

AI Technical Summary

Problems solved by technology

However, in the process of product dehydration and transformation, the reaction time is long and the reaction nodes are not easy to control, the post-treatment is troublesome and the three wastes are discharged more; in the synthesis, due to the large number of active sites of the reactant molecules, it is very easy to produce isomers, these Isomers cannot produce liquid crystal phases. Their appearance not only affects the product yield and increases the cost, but also is a harmful substance in the target compound, which greatly affects the performance of LCD and must be removed. However, their physical and chemical properties are different from those of the target compound. Very close, not easy to separate by conventional methods

[0018] In route B, although alkylcyclohexylphenylboronic acid is relatively easy to obtain, this method uses expensive Pd(0) as a catalyst, and the catalyst is difficult to preserve in daily experiments and production environments. Not conducive to the requirements of industrialized production; and the coupling method yield is not very ideal, about 67%

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