阅读说明：本技术 一种液晶中间体及其制备方法 (Liquid crystal intermediate and preparation method thereof ) 是由 葛会军 李俊 王震 申强 于 2019-03-05 设计创作，主要内容包括：本发明属于液晶化合物的技术领域,具体地说,涉及一种液晶中间体及其制备方法。一种液晶中间体,具有如下式(I)所示的结构：<Image he="176" wi="635" file="DDA0001985830400000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>其中：R选自氢原子,碳数1-7的烷基、烷氧基或氟代直链烷基,或者碳数2-7的直链烯基、烯氧基或氟代直链烯烃基、烃氧基,或者含烷基取代基或氟取代的芳烃基,或者有取代基的含氧或氮的五元或六元杂环基；环E为碳环或含杂原子的杂环；n为自然数。本发明所述的化合物可用于制备多种结构稳定的、高负性液晶单体,为进一步获得性能优异的液晶材料奠定基础。(The invention belongs to the technical field of liquid crystal compounds, and particularly relates to a liquid crystal intermediate and a preparation method thereof. A liquid crystal intermediate having a structure represented by the following formula (I): wherein: r is selected from hydrogen atom, alkyl, alkoxy or fluorinated straight-chain alkyl with 1-7 carbon atoms, or straight-chain alkenyl, alkenyloxy or fluorinated straight-chain alkylene, oxyl with 2-7 carbon atoms, or aryl with alkyl substituent or fluorine substituent, or five-membered or six-membered heterocyclic group containing oxygen or nitrogen and having substituent; ring E is a carbocyclic ring or a heteroatom-containing heterocyclic ring; n is a natural number. The compounds of the inventionThe product can be used for preparing various liquid crystal monomers with stable structures and high negativity, and lays a foundation for further obtaining liquid crystal materials with excellent performance.)

1. A liquid crystal intermediate having a structure represented by the following formula (I):

wherein:

r is selected from hydrogen atom, alkyl, alkoxy or fluorinated straight-chain alkyl with 1-7 carbon atoms, or straight-chain alkenyl, alkenyloxy or fluorinated straight-chain alkylene, oxyl with 2-7 carbon atoms, or aryl with alkyl substituent or fluorine substituent, or five-membered or six-membered heterocyclic group containing oxygen or nitrogen and having substituent; ring E is a carbocyclic ring or a heteroatom-containing heterocyclic ring; n is a natural number.

2. The liquid crystal intermediate of claim 1, wherein R is a c 2-c 7 linear alkyl or alkoxy group.

3. The liquid crystal intermediate according to claim 1 or 2, wherein ring E is selected from phenyl or substituted phenyl, or cycloalkyl or substituted cycloalkyl of 3 to 6 carbon atoms, or cycloalkyl or substituted cycloalkyl of 2 to 5 carbon atoms substituted with an oxygen atom.

4. The liquid crystal intermediate according to any one of claims 1 to 3, wherein ring E is selected from the group consisting of 1, 4-phenylene, 1, 4-cyclohexylene, 1, 4-phenylene substituted with 1 to 4 fluorine atoms,

5. A liquid crystal intermediate according to any one of claims 1 to 4 wherein n is 0 or 1 or 2.

6. A method for preparing a liquid crystal intermediate, which is characterized by using a compound of the following formula (II):

carrying out lithiation reaction and hydrolysis reaction to obtain corresponding aldehyde, and carrying out reduction reaction to obtain the liquid crystal intermediate shown in the formula (I).

7. The process for the preparation of a liquid crystal intermediate according to claim 6, characterized in that the following route is adopted:

Technical Field

The invention belongs to the technical field of liquid crystal compounds, and particularly relates to a liquid crystal intermediate and a preparation method thereof.

Background

In recent ten years, liquid crystal display technology has rapidly developed, and liquid crystal display products have rapidly become popular in people's ordinary lives. The novel liquid crystal display modes mainly include an optically compensated bend mode (OCB), an in-plane switching liquid crystal display (IPS), a vertical alignment mode (VA), an axially symmetric microstructure liquid crystal display (ASM), a multi-domain twisted liquid crystal display, and the like. The liquid crystal cells of various display modes have different designs and different driving modes, and liquid crystal molecular director and glass substrate directions are different, wherein the liquid crystal molecular director and the glass substrate directions of an optical compensated bend mode (OCB) and an in-plane switching liquid crystal display (IPS) are parallel, and the liquid crystal molecular director and the glass substrate directions of a vertical alignment mode (VA) and an axially symmetric microstructure liquid crystal display (ASM) are vertical in a non-electric field state. In the parallel alignment IPS, the dielectric anisotropy (Δ) of the liquid crystal may be positive or negative.

All liquid crystal molecules in a vertical alignment mode (VA) are perpendicular to the direction of the glass substrate in zero field and are parallel to a vertical incident light ray. When the polarizers are crossed, a good dark state is exhibited, so that the device has a good contrast ratio and the dielectric anisotropy (. DELTA.) of the liquid crystal must be negative. The optical anisotropy (Δ η) of the liquid crystal, the thickness (d) of the liquid crystal cell, and the wavelength (λ) of the incident light hardly affect the contrast. The response time of the vertical alignment mode (VA) is much shorter than that of the twisted device, about half or so. Under the influence of an external voltage, the VA device mainly generates bending deformation of liquid crystal molecules, the ECB generates splaying deformation of the liquid crystal molecules, the twist display generates twisting deformation of the liquid crystal molecules, the response time of the twisting deformation is inversely proportional to bending, splaying and twisting elastic constants respectively, and the reason that the response time of the VA device is faster is also because the bending elastic constant of most liquid crystals is larger than the splaying elastic constant and the splaying elastic constant is larger than the twisting elastic constant under the common condition.

In order to make the performance of the display device closer to the ideal, research on new liquid crystal compounds has been conducted, and the performance of the liquid crystal compounds and the display device is continuously advancing. In recent years, many negative materials containing fluorine, cyanogen and the like are widely applied to liquid crystal mixtures, but the performance of the liquid crystal materials is still to be improved, the research and development in the field of liquid crystal materials are still not completed, and in order to improve the performance of liquid crystal display elements, the research and development of novel liquid crystal compounds or early intermediates capable of optimizing the performance of the displays are required to be continuously tried.

The present invention has been made in view of this situation.

Disclosure of Invention

The technical problem to be solved by the invention is to overcome the defects of the prior art and provide a liquid crystal intermediate and a preparation method thereof.

In order to solve the technical problems, the invention adopts the technical scheme that:

a liquid crystal intermediate having a structure represented by the following formula (I):

wherein:

r is selected from hydrogen atom, alkyl, alkoxy or fluorinated straight-chain alkyl with 1-7 carbon atoms, or straight-chain alkenyl, alkenyloxy or fluorinated straight-chain alkylene, oxyl with 2-7 carbon atoms, or aryl with alkyl substituent or fluorine substituent, or five-membered or six-membered heterocyclic group containing oxygen or nitrogen and having substituent; ring E is a carbocyclic ring or a heteroatom-containing heterocyclic ring; n is a natural number.

The liquid crystal intermediate can be used for preparing various liquid crystal monomers with stable structures and high negative, and lays a foundation for further obtaining liquid crystal materials with excellent performance.

In one embodiment, R is a C2-7 linear alkyl or alkoxy group.

In one embodiment, ring E is selected from phenyl or substituted phenyl, or cycloalkyl or substituted cycloalkyl of 3 to 6 carbon atoms, or cycloalkyl or substituted cycloalkyl of 2 to 5 carbon atoms substituted with an oxygen atom.

In one embodiment, ring E is selected from 1, 4-phenylene, 1, 4-cyclohexylene, 1, 4-phenylene substituted with 1 to 4 fluorine atoms,

In one embodiment, n in the above formula is 0 or 1 or 2.

As an embodiment, the liquid crystal intermediate is one of the following substances:

the liquid crystal material correspondingly obtained by the liquid crystal intermediates listed above can obtain higher negativity and show more excellent liquid crystal performance.

Another object of the present invention is to provide a method for preparing a liquid crystal intermediate, which employs a compound of the following formula (II):

carrying out lithiation reaction and hydrolysis reaction to obtain corresponding aldehyde, and carrying out reduction reaction to obtain the liquid crystal intermediate shown in the formula (I).

As an embodiment, the method for preparing the liquid crystal intermediate adopts the following route:

in the formula, the cyclic nitrile (A-1) is a common intermediate in the liquid crystal industry, is easy to obtain and low in price, is added with an aldehyde-based reagent through low-temperature lithiation, is hydrolyzed to obtain an aldehyde product (A-2), is reduced to obtain an alcohol product (A-3), and adopts potassium borohydride as a reducing agent in a reduction reaction, so that the reaction is mild, and the orientation is easy to control to obtain a preset target product. In one embodiment, the lithiation reagent is selected from alkyl lithium or amido lithium, or alkyl lithium/amido lithium + organic solvent. Preferably, the lithiation reagent is butyl lithium, lithium diisopropylamide, 2,6, 6-tetramethylpiperidine + butyl lithium, tetramethylethylenediamine + butyl lithium

In one embodiment, the aldehyde reagent is DMF (N, N-dimethylformamide) or trimethyl orthoformate.

In one embodiment, the lithiation or hydroformylation reaction step employs the following charge ratios, reaction substrates: and (3) lithiation reagent: aldehydizing reagent 1: 1.0-2.0: 1.0-3.0, preferably 1.0: 1.0-1.5: 1.0-1.5.

In one embodiment, the temperature of the lithiation or hydroformylation reaction step is controlled to be-30 to-110 ℃, preferably-60 to-90 ℃.

In one embodiment, the reducing agent is potassium borohydride, sodium borohydride, a solution of red aluminum, lithium aluminum hydride or metal-catalyzed hydrogenation, preferably potassium borohydride or sodium borohydride.

In one embodiment, the reduction step uses the following charge ratio, reaction substrate: the reducing agent is 1:0.3 to 5.0, preferably 1: 0.5 to 1.1; the reaction temperature is-20 to 100 ℃, and preferably 0 to 40 ℃.

In one embodiment, the solvent used in the reduction step is water, tetrahydrofuran, ethanol or methanol.

As an example of the manner in which the device may be used,

the liquid crystal compound of the above formula is prepared into an intermediate derivative having a structure represented by the following formula (III) by further chemical reaction such as halogenation, reduction, oxidation or esterification:

wherein X is selected from the group consisting of-Cl, -Br, -I, -OTs, -OMs, -OSO₂CF₃，-COOH，-CHO。

As an embodiment, the substance of the formula (III) is subjected to etherification reaction, esterification reaction, wittig reaction or hydrogenation reaction to prepare negative ether monomers, esters, alkenes or alkanes, such as the substances shown in the following formula:

wherein the content of the first and second substances,

represents an aromatic hydrocarbon group selected from the following structures:

as an embodiment, specifically, the liquid crystal compound is one of the following structures, such as:

and the like.

Of course, the above structure may be linked to other functional groups to obtain a novel liquid crystal monomer compound.

The liquid crystal compound prepared by the liquid crystal intermediate of the invention shows excellent negative performance and high stability, for example, related experimental data of the liquid crystal compound with the following structure are disclosed in patent application CN201610231181,

showing its excellent performance as a liquid crystal material. The liquid crystal intermediate provides a way for obtaining the liquid crystal compound more cheaply, reduces the preparation difficulty and lays a foundation for obtaining abundant liquid crystal compound materials.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:

FIG. 1 is a mass spectrum of a liquid crystal intermediate (1-3) prepared in example 1 of the present invention;

FIG. 2 is a mass spectrum of the liquid crystal intermediate (2-3) prepared in example 2 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are described in detail and completely with reference to some examples, which are only used for illustrating the present invention and are not used for limiting the scope of the present invention.