Liquid crystal compound containing diacetylene structure, liquid crystal composition and application thereof

文档序号：609283 发布日期：2021-05-07 浏览：30次中文

阅读说明：本技术 一种含丁二炔结构的液晶化合物及其液晶组合物和应用 (Liquid crystal compound containing diacetylene structure, liquid crystal composition and application thereof ) 是由谭小英王艳伟房凤梅王谦姜伟尹环史子谦丰佩川于 2021-01-22 设计创作，主要内容包括：本发明涉及一种如通式I所代表的含丁二炔结构的液晶化合物。本发明还涉及一种液晶组合物,至少包含一种通式I所代表的化合物,具有低熔点、高清亮点、极高的光学各向异性(Δn)和有利的旋转粘度等的特点,本发明所提供的液晶组合物在合适的向列相温度范围内具有稳定性好、响应速度快、介电各向异性高、介电损耗低的优点。(The invention relates to a liquid crystal compound containing a diacetylene structure, which is represented by a general formula I. The invention also relates to a liquid crystal composition, which at least comprises a compound represented by the general formula I, has the characteristics of low melting point, high bright point definition, extremely high optical anisotropy (delta n), favorable rotational viscosity and the like, and has the advantages of good stability, high response speed, high dielectric anisotropy, high dielectric loss and the like in a proper nematic phase temperature rangeLow cost.)

1. A liquid crystal compound containing a diacetylene structure, wherein the liquid crystal compound has a structure shown in a general formula I:

wherein

A₁-A₄Each independently represents:

a)1, 4-phenylene, 1, 4-naphthylene, 2, 6-naphthylene, 1, 4-anthracenylene, 2, 6-anthracenylene, 9, 10-anthracenylene, wherein one or more CH may be replaced by N;

b) trans-1, 4-cyclohexylene or cyclohexenylene, in which one or two non-adjacent CH' s₂The radicals may also be replaced by-O-and/or-S-, and where H may be replaced by F;

c) thiophene-2, 5-diyl, thiophene-2, 4-diyl, furan-2, 5-diyl, furan-2, 4-diyl;

and in a), b) and c) one or more H atoms may also be replaced by-Br, -Cl, -F, -CN, -NCS, -SCN, -SF₅Halogenated or non-halogenated alkyl of 1 to 10 carbon atoms, alkoxy, halogenated or non-halogenated alkenyl of 2 to 10 carbon atoms, alkenyloxy, cycloalkyl of less than 6 carbons, cycloalkenyl;

and wherein A₂、A₃At least one group represents the group in a);

R₁、R₂each independently represents: F. cl, Br, CN, CF₃、OCF₃SCN, NCS or SF₅(ii) a Halogenated or unhalogenated with 1 to 10 carbon atomsAlkyl radicals in which one or more CH groups are present₂The radicals may also be replaced, independently of one another, by-C.ident.C-, -CH-, -CF-, -CF-CH-, -CH-CF-, - (CO) O-, -O (CO) -, -O-or-S-in such a way that the O or S atoms are not directly linked to one another.

Z₁、Z₂Each independently represents: single bond, -CH-, -CF-CH-, -C.ident.C-, -CF₂O-、-CH₂O-、-CH₂-CH₂-、-CF₂CF₂-、-CH₂CF₂-、-(CO)O-；

n and m each independently represent 0,1 or 2.

2. The liquid crystal compound of claim 1, wherein the general formula I is selected from one or more of the following compounds:

3. the liquid crystal compound of claim 2, wherein the group R₁Or R₂Represents an alkyl group having 1 to 10C atoms, wherein in these groups one or more CH groups₂The radicals may also be replaced, independently of one another, by-C.ident.C-, -CH-, -CF-, -CF-CH-, -CH-CF-, - (CO) O-, -O (CO) -, -O-or-S-in such a way that the O or S atoms are not directly linked to one another. Particularly preferably, R₁And R₂One represents alkyl and the other represents alkyl or alkoxy, and very particularly preferably R₁And R₂Have different meanings from each other.

4. The liquid crystal compound of claim 2, wherein the general formula I is selected from one or more of the following compounds:

5. a liquid crystal composition, wherein the liquid crystal composition at least comprises the compound represented by the general formula I according to any one of claims 1 to 4, and the proportion of the general formula I is 3 to 60 weight percent relative to the total mass of the liquid crystal composition.

6. The liquid crystal composition of claim 5, further comprising a compound of formula II to formula III;

the compound represented by the general formula II is:

the compound represented by the general formula III is:

wherein A is₅、A₆、A₇–A₉Each independently represents:

R₃、R₄、R₅、R₆each independently represents: F. cl, Br, CN, CF₃、OCF₃SCN, NCS or SF₅(ii) a Halogenated or non-halogenated, alkyl or alkoxy of 1 to 10 carbon atoms, alkenyl or alkenyloxy of 2 to 10 carbon atoms;

Z₃、Z₄、Z₅each independently represents: a single bond, -CH-, -CF-, -CH-, -C ≡ C-.

7. The liquid crystal composition of claim 6, wherein the compound represented by the general formula II is selected from one or more of the following compounds:

wherein the radical R₃Or R₄At least one of which represents an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl or alkenyloxy group having 2 to 10 carbon atoms, and very particularly preferably R₃And R₄Have different meanings from each other.

8. The liquid crystal composition of claim 6, wherein the compound represented by the general formula III is selected from one or more of the following compounds:

wherein the radical R₅Or R₆At least one of which represents an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl or alkenyloxy group having 2 to 10 carbon atoms, and very particularly preferably R₅And R₆Have different meanings from each other.

9. The liquid crystal composition of claim 6, wherein the proportion of the compound represented by the general formula II is 10 to 50 wt% based on the total mass of the liquid crystal composition; the proportion of the general formula III is 10-50 wt%.

10. Use of a liquid crystal composition for components in the microwave and millimeter wave region of the high frequency technology or electromagnetic spectrum, in particular phase shifters and microwave array antennas.

Technical Field

The invention relates to a liquid crystal compound containing a diacetylene structure, a liquid crystal composition and application thereof.

Background

The liquid crystal material has been applied to the display field with great success, and as a special photoelectric material, the research on the application of the liquid crystal material to tunable microwave components has attracted much attention in recent years. The research on liquid crystal materials suitable for the microwave field in China is in the initial stage, and the overall level has a relatively large gap compared with the similar research in foreign countries. The most representative of these is the Merck company in Germany, which has searched for the relationship between the molecular structure of liquid crystals and the microwave properties and has conducted intensive research.

Unlike conventional display devices, microwave devices require liquid crystal materials to have large dielectric tuning rates, low dielectric loss values, high quality factors, and wide nematic phase temperature ranges. Merck corporation issued several patents and articles relating to liquid crystal phase shifters and microwave antennas, for example merck issued patent No. CN102575165B discloses liquid crystal compounds containing bis-diphenylacetylenes of the formula:

the results of the studies show that liquid crystal compounds based on a bis-tolane skeleton have both high tuning rate and low loss values, which techniques are now known to those skilled in the art. However, the liquid crystal compound containing the bis-tolane skeleton has the disadvantages of high melting point, poor compatibility and the like, and the application of the liquid crystal compound in a mixed liquid crystal formula is limited. The compounds or compositions known to date also generally suffer from serious disadvantages: disadvantageously high losses, insufficient phase shift, minimal material quality and poor low temperature performance, etc., limit the practical application of liquid crystals in high frequency technology, and new liquid crystal media with improved properties are required.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention provides a liquid crystal compound containing a diacetylene structure. The compounds of the invention have a low melting point, a high clearing point, a very high optical anisotropy (. DELTA.n) and a favourable rotational viscosity.

The invention provides a liquid crystal compound, which has a structure shown in a general formula I:

wherein

A₁-A₄Each independently represents:

d)1, 4-phenylene, 1, 4-naphthylene, 2, 6-naphthylene, 1, 4-anthracenylene, 2, 6-anthracenylene, 9, 10-anthracenylene, wherein one or more CH may be replaced by N;

e) trans-1, 4-cyclohexylene or cyclohexenylene, in which one or two non-adjacent CH' s₂The radicals may also be replaced by-O-and/or-S-, and where H may be replaced by F;

f) thiophene-2, 5-diyl, thiophene-2, 4-diyl, furan-2, 5-diyl, furan-2, 4-diyl;

and wherein A₂、A₃At least one group represents the group in a);

R₁、R₂each independently represents: F. cl, Br, CN, CF₃、OCF₃SCN, NCS or SF₅(ii) a Halogenated or unhalogenated alkyl groups having 1 to 10 carbon atoms, in which one or more CH groups are present in these radicals₂The radicals may also be replaced, independently of one another, by-C.ident.C-, -CH-, -CF-, -CF-CH-, -CH-CF-, - (CO) O-, -O (CO) -, -O-or-S-in such a way that the O or S atoms are not directly linked to one another.

Z₁、Z₂Each independently represents: single bond, -CH-, -CF-CH-, -C.ident.C-, -CF₂O-、-CH₂O-、-CH₂-CH₂-、-CF₂CF₂-、-CH₂CF₂-、-(CO)O-；

n and m each independently represent 0,1 or 2.

Preferably, structural formula I is selected from one or more of the following compounds:

preferably, the group R₁Or R₂Represents an alkyl group having 1 to 10C atoms, wherein in these groups one or more CH groups₂The radicals may also be replaced, independently of one another, by-C.ident.C-, -CH-, -CF-, -CF-CH-, -CH-CF-, - (CO) O-, -O (CO) -, -O-or-S-in such a way that the O or S atoms are not directly linked to one another. Particularly preferably, R₁And R₂One represents alkyl and the other represents alkyl or alkoxy, and very particularly preferably R₁And R₂Have different meanings from each other.

More preferably, the compounds I according to the invention have a clearly positive dielectric anisotropy, the corresponding compounds particularly preferably having the following structure:

the compounds of the invention have a low melting point, a high clearing point, a very high optical anisotropy (. DELTA.n) and a favourable rotational viscosity. Alone or mixed with further liquid-crystalline components, which have a nematic phase over a wide temperature range, these properties make them particularly suitable for components for high-frequency technology, in particular in liquid-crystal phase shifters.

The invention also provides a liquid crystal composition, which at least comprises a compound represented by the general formula I, wherein the proportion of the general formula I is 3-60 weight percent, preferably 15-50 weight percent, and more preferably 20-45 weight percent relative to the total weight of the liquid crystal composition.

Preferably, the liquid crystal composition also comprises compounds shown in general formulas II to III;

the compound represented by the general formula II is:

the compound represented by the general formula III is:

wherein A is₅、A₆、A₇–A₉Each independently represents:

R₃、R₄、R₅、R₆each independently represents: F. cl, Br, CN, CF₃、OCF₃SCN, NCS or SF₅(ii) a Halogenated or non-halogenated, alkyl of 1 to 10 carbon atoms orAlkoxy, alkenyl or alkenyloxy of 2 to 10 carbon atoms;

Z₃、Z₄、Z₅each independently represents: a single bond, -CH-, -CF-, -CH-, -C ≡ C-.

Preferably, the compound represented by formula II is selected from one or more of the following compounds:

preferably, the group R₃Or R₄At least one of which represents an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl or alkenyloxy group having 2 to 10 carbon atoms, and very particularly preferably R₃And R₄Have different meanings from each other.

Preferably, the proportion of the general formula II is 10 to 50 weight percent, preferably 20 to 50 weight percent, and more preferably 25 to 45 weight percent, relative to the total weight of the liquid crystal composition.

Preferably, the compound represented by formula III is selected from one or more of the following compounds:

preferably, the group R₅Or R₆At least one of which represents an alkyl or alkoxy group having 1 to 10 carbon atoms, an alkenyl or alkenyloxy group having 2 to 10 carbon atoms, and very particularly preferably R₅And R₆Have different meanings from each other.

The liquid crystal composition is characterized in that the proportion of the general formula III is 10-50 weight percent, preferably 10-40 weight percent, and more preferably 15-35 weight percent relative to the total weight of the liquid crystal composition.

The invention also provides the use of a liquid crystal composition which is suitable for components in the microwave region as well as in the millimeter wave region of the high-frequency technology or electromagnetic spectrum, in particular phase shifters and microwave array antennas.

Has the advantages that: the liquid crystal compound has a diacetylene-containing structure with at least two ring systems, and the central connecting group of the ring systems is diacetylene. The compounds are used in high-frequency technology or in components in the microwave region and in the millimeter-wave region of the electromagnetic spectrum, in particular phase shifters and microwave array antennas. .

Detailed Description

The liquid crystal compositions in embodiments of the invention comprise one or more compounds of formula I, which can be advantageously prepared according to the following exemplary synthesis:

example 1:

example 2:

example 3:

example 4:

example 5:

the percentages in the following examples represent percentages by weight, unless otherwise specified.

Cp (. degree. C.) represents the clearing point.

DELTA.n represents the optical anisotropy at 20 ℃ of 589 nm.

DELTA ε represents the dielectric anisotropy at 20 ℃.

ε | represents the liquid crystal dielectric constant in the parallel state.

ε ^ represents the liquid crystal dielectric constant in the vertical state.

γ 1 (mPas) represents the rotational viscosity at 20 ℃.

Vo (V) represents the threshold voltage at 20 ℃.

τ represents the material tunability.

ε r, | represents the liquid crystal dielectric constant at a certain frequency band in the parallel state.

ε r,. quadrature.represents the liquid crystal dielectric constant at a certain frequency band in the vertical state.

tan δ ε r, | represents the loss tangent value in the parallel state.

tan δ ∈ r,. DELTA.represents a loss tangent value in the vertical state.

η represents a material quality factor.

For convenience of expression, in the following examples, the structures of liquid crystal compounds are represented by abbreviations. Table a lists the codes for the ring structures, table B lists the codes for the linker groups, and table C lists the codes for the terminal groups.

Structure of the watch ring

TABLE B linking groups

TABLE C end groups

Structural formula I and code referred to in the examples:

structural formula II and code referred to in the examples:

structural formula III and code referred to in the examples:

example 1:

liquid crystal compound monomer IThe preparation method comprises the following steps:

step 1 preparation of I-1

Under the protection of nitrogen, 144g of 4-propylphenylacetylene and 1200ml of anhydrous tetrahydrofuran are added into a three-necked flask, stirred for 10 minutes and then cooled to-80 ℃. 500ml of 2.5M butyl lithium is dripped, and the temperature is controlled to be-75 ℃ to-85 ℃ in the whole process. After the addition, the mixture was kept warm for 1 hour, followed by addition of 180g of NBS (N-bromosuccinimide) in portions. After the addition was completed, the temperature was gradually raised to room temperature, and then the reaction solution was slowly poured into a saturated ammonium chloride solution, and the aqueous layer was extracted with ethyl acetate, and the organic layers were combined and washed with saturated brine. The organic layer was dried, filtered and desolventized in vacuo. The crude product was passed through a silica gel column to obtain 200g of I-1 intermediate.

Step 2 preparation of I-2

Under the protection of nitrogen, 112g of raw material R-1, 150ml of triethylamine, 300ml of toluene, 10.4g of triphenylphosphine and 1.9g of cuprous iodide are added into a three-neck flask, the temperature is raised to 60 ℃, 1.5g of palladium tetrakis (triphenylphosphine) is added, 60g of trimethylacetylene silicon is added dropwise, the dropwise addition is finished within about 2 hours, the temperature is raised and the reflux is carried out after the dropwise addition is finished, and the reaction is carried out for 5 hours. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, saturated ammonium chloride, dried over anhydrous sodium sulfate, passed through a silica gel column and finally crystallized to obtain 90g of intermediate I-2.

Step 3 preparation of I-3

2.4g of cuprous chloride and 1500ml of DMF were added to a three-necked flask, followed by 82.5g of intermediate I-1. After stirring for 15 minutes, the temperature was raised to 80 ℃ and a solution prepared by dissolving 62.5g of intermediate I-2 in 120ml of DMF was added dropwise to a three-necked flask. After the dropwise addition, the temperature is kept for 10 hours, and the reaction is finished. Cooling to room temperature, adding hydrochloric acid into the three-neck bottleAcidification, aqueous layer with methyl tert butyl ether extraction, combined organic layer, sodium bicarbonate aqueous solution washing, brine washing, drying, filtering, vacuum desolventizing, 77g crude product. SiO 2₂After the column, desolventization in vacuo and recrystallization, 50g of I-3 were obtained.

Preparation of monomer I in step 4

42g N, N' -thiocarbonyldiimidazole and 260ml anhydrous DMF were added to a three-necked flask under nitrogen protection, and stirred to dissolve completely. The temperature is reduced to-10 ℃, and the solution of the intermediate 60g I-3 and 250ml DMF is added dropwise. After the dropwise addition, the temperature is kept between minus 10 ℃ and 0 ℃ for 1 hour, then the temperature is naturally raised to the room temperature, and the mixture is stirred overnight. The temperature is reduced to 0 ℃ the next day, and sodium bicarbonate solution is slowly added into the reaction bottle. After the addition, stirring for 30 minutes, adding ethyl acetate for extraction, drying with anhydrous sodium sulfate, filtering, and vacuum desolventizing to obtain 60g of crude product. The crude product was crystallized from toluene to give 36g of pure product.

Example 2:

liquid crystal compound monomer IIThe preparation method comprises the following steps:

wherein the preparation process of II-4 is as follows:

step 1 preparation of II-1

Adding deionized water into a three-mouth bottle under the protection of nitrogen: 600g, turn on stirring, add potassium carbonate: 300g, stirred for about 10 minutes to dissolve completely, and added THF: 1000ml of 4-propylphenylboronic acid 172. After the addition, nitrogen is introduced to replace the air in the kettle for 30 minutes, the temperature is raised to 55 ℃, 5g of catalyst tetrakis (triphenylphosphine) palladium is added under the protection of nitrogen, after the heating is carried out until the reflux, the THF solution of R-2 (300g of R-2 is dissolved in 640ml of THF) is added dropwise, and the dropwise addition process is carried out for 6 hours. And after the dropwise addition is finished, continuously preserving the heat until the R-2 reaction is finished, cooling to 30-40 ℃, and standing for layering. The aqueous phase was separated and extracted with toluene. The organic phases are combined and washed by water, and the organic phases are vacuum desolventized. Cooling to 30-40 deg.C, passing through SiO₂And (5) performing column crystallization to obtain 225g of a target product.

Step 2 preparation of II-2

Under nitrogen protection, 150g of the prepared intermediate II-1 was added to a three-necked flask, and 250ml of triethylamine, toluene: 300ml of cuprous iodide and 1.9g of cuprous iodide, heating to 60 ℃, and adding PdCl₂(PPh₃)₂1.5g of a triethylamine solution of trimethylethynyl silicon (prepared by dissolving 100g of trimethylethynyl silicon in 150ml of triethylamine) was added dropwise over about 2 hours, and after the addition was completed, the mixture was refluxed at elevated temperature and reacted for 5 hours. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, saturated ammonium chloride, dried over anhydrous sodium sulfate, passed through a silica gel column and crystallized to obtain 142g of intermediate II-2.

Step 3 preparation of II-3

Under the protection of nitrogen, 130g of intermediate II-2, 138g of anhydrous potassium carbonate and 500ml of methanol are added into a three-necked bottle, the mixture is heated to 40 ℃, the temperature is kept for 8 hours, and no raw material is remained after detection. Suction filtration is carried out, and the filter cake is rinsed by toluene. Vacuum desolventizing and passing through SiO₂Column, 100g of product was obtained and used directly in the next reaction.

Step 4 preparation of II-4

Under the protection of nitrogen, 72g of intermediate II-3 and 900ml of anhydrous tetrahydrofuran are added into a three-necked flask, stirred for 10 minutes and then cooled to-80 ℃. 500ml of 2.5M butyl lithium is dripped, and the temperature is controlled to be-75 ℃ to-85 ℃ in the whole process. After the completion of the dropwise addition, the mixture was kept warm for 1 hour, and then 45g of NCS (N-chlorosuccinimide) was added in portions. After the addition was completed, the temperature was gradually raised to room temperature, and then the reaction solution was slowly poured into a saturated ammonium chloride solution, and the aqueous layer was extracted with ethyl acetate, and the organic layers were combined and washed with saturated brine. The organic layer was dried, filtered and desolventized in vacuo. The crude product was passed through a silica gel column to give 75g of intermediate I-1.

Step 5 preparation of II-5

Under the protection of nitrogen, 220g of raw material R-3, 150ml of triethylamine, 500ml of toluene, 20g of triphenylphosphine and 2.2g of cuprous iodide are added into a three-neck flask, the temperature is raised to 60 ℃, 5g of palladium tetrakis (triphenylphosphine) is added, 130g of trimethylacetylene silicon is added dropwise, the dropwise addition is completed within about 3 hours, the temperature is raised continuously and the reflux is carried out after the dropwise addition is completed, and the reaction is carried out for 6 hours. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, saturated ammonium chloride, dried over anhydrous sodium sulfate, passed through a silica gel column and crystallized to obtain 165g of intermediate II-5.

Step 6 preparation of II-6

2.4g of cuprous chloride and 1500ml of DMF were added to a three-necked flask, followed by 56g of intermediate II-3. After stirring for 15 minutes, the temperature was raised to 80 ℃ and a solution prepared by dissolving 75g of intermediate II-5 in 120ml of DMF was added dropwise to a three-necked flask. After the dropwise addition, the temperature is kept for 10 hours, and the reaction is finished. Cooling to room temperature, adding hydrochloric acid into a three-necked flask, acidifying, extracting the aqueous layer with methyl tert-butyl ether, combining the organic layers, washing with aqueous sodium bicarbonate solution, washing with brine, drying, filtering, and vacuum desolventizing to obtain 77g of crude product. SiO 2₂After the column, desolventization in vacuo and recrystallization, 150g of II-6 were obtained.

Preparation of monomer II in step 7

42g N, N' -thiocarbonyldiimidazole and 260ml anhydrous DMF were added to a three-necked flask under nitrogen protection, and stirred to dissolve completely. The temperature is reduced to-10 ℃, and the solution of the intermediate 70g of II-6 and 450ml of DMF is added dropwise. After the dropwise addition, the temperature is kept between 0 and 10 ℃ for 5 hours, then the temperature is naturally raised to the room temperature, and the mixture is stirred overnight. The temperature is reduced to 0 ℃ the next day, and sodium bicarbonate solution is slowly added into the reaction bottle. After the addition, stirring for 30 minutes, adding ethyl acetate for extraction, drying with anhydrous sodium sulfate, filtering, and vacuum desolventizing to obtain 60g of crude product. The crude product was crystallized from ethyl acetate to obtain 55g of a single crystal II pure product.

Example 3:

liquid crystal compound monomer IIIThe preparation method comprises the following steps:

step 1 preparation of III-1

Under the protection of nitrogen, 282g of dry 4-bromoiodobenzene and 750ml of anhydrous triethylamine cuprous iodide 3g are added into a three-necked bottle, the temperature is raised to 60 ℃, and 1.5g of newly prepared catalyst PdCl is added₂(PPh₃)₂Subsequently, a solution of 145g of 4-ethylphenylacetylene in 290ml of THF was added dropwise thereto over a period of about 5 hours, and after completion of the addition, the mixture was refluxed at elevated temperature and reacted for 2 hours. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, 10% hydrochloric acid, saturated brine, dried over anhydrous sodium sulfate, passed through a silica gel column and crystallized to obtain 254g of intermediate III-1.

Step 2 preparation of III-2

200g of III-1, 1050ml of anhydrous triethylamine, 4g of cuprous iodide and 90g of trimethylacetylene silicon are added into a three-necked flask, nitrogen is used for purging for 30 minutes, the mixture is stirred and heated to 60 ℃, and 2.5g of newly prepared catalyst PdCl is added₂(PPh₃)₂The reaction was incubated at 70 ℃ for 12 hours. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, saturated ammonium chloride, saturated brine, dried over anhydrous sodium sulfate, filtered, and vacuum-desolventized to give 190g of intermediate III-2.

Step 3 preparation of III-3

189g of raw material R-4, 350ml of triethylamine, 500ml of toluene, 130g of trimethylacetylene silicon, 10.2g of triphenylphosphine and 2.4g of cuprous iodide are added into a three-mouth bottle under the protection of nitrogen, the temperature is raised to 60 ℃, 3.5g of tetrakis (triphenylphosphine) palladium is added, and the mixture is heated and refluxed for 12 hours after the addition is finished. Filtering, and leaching a filter cake with toluene. The filtrate was washed with water, 15% hydrochloric acid, saturated brine, dried over anhydrous sodium sulfate, and filtered. The filtrate was subjected to the subsequent operation.

Adding the filtrate prepared above, 650ml of methanol and 230g of potassium carbonate into a three-neck flask, and reacting overnight at the temperature of 20-25 ℃. Filtering, leaching the filtrate with toluene, combining organic layers, and vacuum desolventizing. The residue obtained, SiO₂Column, 100g of intermediate III-3 were obtained.

Step 4 preparation of III-4

Under the protection of nitrogen, 93.8g of intermediate III-3 and 500ml of anhydrous tetrahydrofuran are added into a three-necked flask, stirred for 10 minutes and then cooled to-80 ℃. 350ml of 2.5M butyl lithium is dripped, and the temperature is controlled to be-75 ℃ to-85 ℃ in the whole process. After the addition, the mixture was allowed to stand for 1 hour, followed by addition of 112g of NBS (N-bromosuccinimide) in portions. After the addition was completed, the temperature was gradually raised to room temperature, and then the reaction solution was slowly poured into a saturated ammonium chloride solution, and the aqueous layer was extracted with ethyl acetate, and the organic layers were combined and washed with saturated brine. The organic layer was dried, filtered and desolventized in vacuo. The crude product was passed through a silica gel column to give 125g of intermediate III-4.

Step 5 preparation of III

3.5g of cuprous chloride and 1500ml of DMF were added to a three-necked flask followed by 105g of intermediate III-4. After stirring for 15 minutes, the temperature was raised to 80 ℃ and a solution prepared by dissolving 155g of intermediate III-2 with 210ml of DMF was added dropwise to a three-necked flask. After the dropwise addition, the temperature is kept for 4 hours, and the reaction is finished. Cooling to room temperature, adding hydrochloric acid into a three-necked flask, acidifying, extracting the aqueous layer with methyl tert-butyl ether, combining the organic layers, washing with aqueous sodium bicarbonate solution, washing with brine, drying, filtering, and vacuum desolventizing to obtain 170g of crude product. SiO 2₂After the column, vacuum desolventization and recrystallization, 115 g of single-crystal monomer III was obtained.

Example 4:

liquid crystal compound monomer IvThe preparation method comprises the following steps:

step 1 preparation of Iv-1

With reference to the production method of III-1, Iv-1 can be produced by substituting 4- (4-propylcyclohexylphenyl) phenylacetylene for the starting 4-ethylphenylacetylene.

Step 2 preparation of Iv-2

Referring to the preparation methods of II-2 and II-3, the raw material II-1 is replaced by IV-1, and the IV-2 is prepared through a two-step reaction.

Step 3 preparation of Iv-3

Referring to the preparation method of II-4, IV-3 is prepared by replacing the raw material II-3 with IV-2 through reaction.

Step 4 preparation of Iv-4

Referring to the preparation method of II-5, the raw material R-3 is replaced by R-5, and Iv-4 is prepared through reaction.

Step 5 preparation of Iv-5

Referring to the preparation method of II-6, IV-5 is used for replacing raw material II-5, and IV-3 is used for replacing raw material II-3, and IV-5 is prepared through reaction.

Preparation of Iv in step 6

Referring to the preparation method of II, the raw material II-6 is replaced by IV-5 to prepare the monomer IV through reaction.

Example 5:

liquid crystal compound monomerThe preparation method comprises the following steps:

step 1 preparation of V-1

Referring to step 3 of compound II, i.e., the preparation method of II-3, raw material II-2 is replaced by III-2 (prepared according to the preparation method of step 2 of compound III), and V-1 can be obtained by potassium carbonate cracking.

Step 2 preparation of V-2

Referring to the step 4 of the compound III, the preparation method of III-4, the raw material III-3 is replaced by V-1, and the compound is prepared by butyl lithium metal replacement and bromination.

Step 3 preparation of V-3

Referring to the step 1 of the compound III, the preparation method of the compound III-1 is to replace 4-ethyl phenylacetylene as a raw material with 3,4, 5-trifluoro-phenylacetylene, and prepare the compound by Sonogashira coupling.

Step 4 preparation of V-4

Referring to the step 2 of the compound III, the preparation method of III-2, the raw material III-1 is replaced by V-3, and the compound is prepared by coupling.

Step 5 preparation of V-5

Referring to the 5 th step of the compound III, the preparation method of the compound III is to replace the raw material III-2 with III-2 and replace the raw material III-4 with III-2, and the compound is prepared by cuprous chloride catalytic coupling.

Example 6: