Preparation method of 4-(allyl)-4-methyl-1, 1 '-biphenyl liquid crystal monomer

Abstract

The invention discloses a preparation method of a 4-(allyl)-4-methyl-1, 1 '-biphenyl liquid crystal monomer, which comprises the following steps: S1, by taking p-phenylboronic acid, dechlorobenzyl alcohol, Pd / Cl and sodium carbonate as raw materials, reacting for 1-12 hours in a toluene and water system under the protection of nitrogen to obtain 4'-methyl-[1, 1 '-biphenyl]-4-benzyl alcohol (intermediate 1); s2, taking the intermediate 1 and hydrochloric acid as raw materials, and petroleum ether, toluene or ethanol as a solvent to obtain 3-(chloromethyl)-4 '-methyl-1, 1'-biphenyl (intermediate 2); s3, finally, chloropropene, the intermediate 2, magnesium particles and dibromoethane are used as raw materials, and tetrahydrofuran, petroleum ether or methylbenzene is used as a solvent; according to the present invention, the target compound is synthesized by using the existing raw materials and the technical equipment, such that the use amount of the catalyst is small, the catalytic efficiency is high, and compared with the hydrogen bromide, the corrosion on the equipment is weak, the conversion rate is high, the yield is high, the post-treatment process is simple, and the cost is reduced and the effect is improved.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display materials technology, and in particular to a method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer. Background Technology

[0002] With continuous economic development, people's demands for a high-quality life are constantly increasing, especially the demand for high-quality display devices. Liquid crystal display (LCD) materials are one of the important materials for manufacturing high-quality display devices, hence the large market demand for LCD materials. Liquid crystal monomers are an important component of liquid crystal materials, and the quality of liquid crystal materials directly affects the quality of the LCD panel and the overall performance of the LCD display. Liquid crystal materials are the core component of LCD panels, determining the brightness, contrast, color, and viewing angle of the LCD display. With the profit margin of liquid crystal materials continuously declining, developing high-performance, low-cost LCD materials has become an important topic for further research. Summary of the Invention

[0003] To address the problems mentioned in the background section, this invention provides a method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer, using p-phenylmethylboric acid and hypochlorous acid as raw materials, and obtaining 4'-methyl-[1,1'-biphenyl]-4-benzyl alcohol (intermediate 1) via a Pd / Cl catalytic reaction, with the following structural formula: .

[0006] The specific plan includes the following steps:

[0007] S1. Using p-phenylmethylboronic acid, hypochlorous acid, Pd / Cl, and sodium carbonate as raw materials, under nitrogen protection, in a toluene and water system, at a reaction temperature of 50-90℃, for 1-12 hours, 4'-methyl-[1,1'-biphenyl]-4-benzyl alcohol (intermediate 1) was obtained, with a raw material conversion rate of 99%.

[0008] The molar concentration of toluene solvent is 0.5~2 mol / L, the volume ratio of water to solvent is 1:(2-10), and the mass ratio of p-phenylmethylboric acid, hypochlorous acid, Pd / Cl, and sodium carbonate is 1:(1-2):(0.0002-0.01):(0.5-1.5).

[0009] S2. Using intermediate 1 and hydrochloric acid (concentration 20-40%) as raw materials, and petroleum ether, toluene, or ethanol as solvents, with a molar concentration of 0.5-2 mol / L, and a mass ratio of intermediate 1 to hydrochloric acid (concentration 20-40%) of 1:(2-5), under nitrogen protection, at a reaction temperature of 50-80℃, for 1-20 h, 3-(chloromethyl)-4'-methyl-1,1'-biphenyl (intermediate 2) is obtained, with the following structural formula: ;

[0010] S3. Finally, using allyl chloride, intermediate 2, magnesium granules, and dibromoethane as raw materials, and tetrahydrofuran, petroleum ether, or toluene as solvents, the mass ratio of intermediate 2, allyl chloride, and magnesium granules is 1:(1.1-3):(1.2-5), and the mass ratio of dibromoethane to intermediate 2 is (0.005-0.1):1.

[0011] First, a Grignard reagent was prepared. Using magnesium granules, dibromoethane, and a solvent as substrates, a mixture of allyl chloride and solvent was added dropwise under nitrogen protection to initiate the reaction at 10-50℃. After initiation, the temperature was lowered to -20~0℃, and the remaining solution was added dropwise under controlled temperature. The reaction was allowed to proceed for 1-6 hours. Excess magnesium granules were filtered off, and then a mixture of intermediate 2 and solvent was added dropwise at -20~10℃. The reaction was allowed to proceed for 1-15 hours to obtain the final product, 4-(allyl)-4-methyl-1,1'-biphenyl, with the following structural formula: .

[0012] Compared with the prior art, the beneficial effects of the present invention are:

[0013] This invention utilizes existing raw materials and technical equipment to synthesize the target compound. The coupling raw materials are simpler and cheaper than those of brominated derivatives, with shorter reaction times, fewer byproducts, smaller catalyst dosage, and higher catalytic efficiency. The use of hydrochloric acid in halogenation is less corrosive to equipment than hydrogen bromide, resulting in higher conversion and yield. The post-processing steps are simple, reducing costs and increasing efficiency. Grignard preparation lowers the reaction temperature, making the reaction more mild and controllable, and reducing production risks. Detailed Implementation

[0014] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0016] Structure of 4-(allyl)-4-methyl-1,1'-biphenyl compound:

[0017]

[0018] Compound molecular formula: C17H18, MS: 222.14 g / mol.

[0019] Preparation Example

[0020] S1. Using 100g of p-phenylmethylboric acid, 100g of hypochlorous acid, 1g of Pd / Cl, and 50g of sodium carbonate as raw materials, under nitrogen protection, in a system of 100mL of 0.5mol / L toluene and 200mL of water, the temperature was raised to 80℃ and the reaction was carried out for 10h to obtain 4'-methyl-[1,1'-biphenyl]-4-benzyl alcohol (intermediate 1), with a raw material conversion rate of 99%.

[0021] S2. Using 100g of intermediate 1 and 200g of 30% hydrochloric acid as raw materials, and petroleum ether with a molar concentration of 1mol / L as solvent, the reaction temperature is 75℃ and the reaction is carried out for 8h to obtain 3-(chloromethyl)-4'-methyl-1,1'-biphenyl (intermediate 2), with a raw material conversion rate of 98%.

[0022] Example 1

[0023] Add 22.15g of magnesium granules, 100ml of tetrahydrofuran, and 0.5g of dibromoethane to a 1L reactor. Add 5ml of diluted allyl chloride and initiate the reaction at 25℃. After initiation, add the remaining 45.94g of allyl chloride and 200ml of tetrahydrofuran mixed solution. Control the temperature at -5℃ and react for 3h. Filter out excess magnesium shavings. Then add 100g of intermediate 2 prepared in the preparation example + 300ml of tetrahydrofuran mixed solution. The mass ratio of intermediate 2, allyl chloride, and magnesium granules is 1:1.3:2.0. React at -5℃ and stir for 4h. The final product has a controlled purity of 91%.

[0024] Example 2

[0025] 22.15 g of magnesium granules, 100 ml of tetrahydrofuran, and 0.5 g of dibromoethane were added to a 1 L reactor. 5 ml of diluted allyl chloride was added dropwise to initiate the reaction at 25 °C. After initiation, the remaining 49.47 g of allyl chloride and 200 ml of the tetrahydrofuran mixture were added dropwise. The reaction was carried out at -8 °C for 3 hours. Excess magnesium shavings were filtered off. Then, 100 g of intermediate 2 prepared in the preparation example and 300 ml of the tetrahydrofuran mixture were added dropwise. The mass ratio of intermediate 2, allyl chloride, and magnesium granules was 1:1.4:2.0. The reaction was carried out at -10 °C with stirring for 4 hours. The final product had a controlled purity of 93%.

[0026] Example 3

[0027] Add 22.15g of magnesium granules, 100ml of tetrahydrofuran, and 0.5g of dibromoethane to a 1L reactor. Initiate the reaction at 25°C by adding 5ml of diluted allyl chloride dropwise. After initiation, add the remaining 53g of allyl chloride and 200ml of the tetrahydrofuran mixture dropwise. Maintain the temperature at -10°C and react for 3 hours. Filter out excess magnesium shavings. Then add 100g of intermediate 2 prepared in the preparation example + 300ml of the tetrahydrofuran mixture. The mass ratio of intermediate 2, allyl chloride, and magnesium granules is 1:1.5:2.0. React at -5°C with stirring for 4 hours. The final product has a controlled purity of 98%.

[0028] Comparative Example 1

[0029] Add 22.15g of magnesium granules, 100ml of tetrahydrofuran, and 0.5g of dibromoethane to a 1L reactor. Initiate the reaction at 25℃ by adding 5ml of diluted allyl chloride dropwise. After initiation, add the remaining 45.94g of allyl chloride and 200ml of tetrahydrofuran solution dropwise. Maintain the temperature at -10℃ and react for 3 hours. Filter out excess magnesium shavings. Then add 83g of intermediate 2 + 300ml of tetrahydrofuran solution. The mass ratio of intermediate 2, allyl chloride, and magnesium granules is 1:1.3:2.0. React at -5℃ with stirring for 4 hours. The final product has a controlled purity of 78%, with intermediate 2 being... .

[0030] Comparative Example 2

[0031] Add 22.15g of magnesium granules, 100ml of tetrahydrofuran, and 0.5g of dibromoethane to a 1L reactor. Initiate the reaction at 25℃ by adding 5ml of diluted allyl chloride dropwise. After initiation, add the remaining 49.47g of allyl chloride and 200ml of tetrahydrofuran solution dropwise. Maintain the temperature at -5℃ and react for 3 hours. Filter out excess magnesium shavings. Then add 83g of intermediate 2 + 300ml of tetrahydrofuran solution. The mass ratio of intermediate 2, allyl chloride, and magnesium granules is 1:1.3:2.0. React at -10℃ with stirring for 4 hours. The final product has a controlled purity of 83%, of which intermediate 2 is... .

[0032] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer, characterized in that, Includes the following steps: S1. Using p-phenylmethylboronic acid, hypochlorous acid, Pd / Cl, and sodium carbonate as raw materials, under nitrogen protection, in a toluene and water system, at a temperature of 50-90℃ for 1-12 h, 4'-methyl-[1,1'-biphenyl]-4-benzyl alcohol (intermediate 1) is obtained, with the following structural formula: ； S2. Using intermediate 1 and hydrochloric acid as raw materials, and petroleum ether, toluene, or ethanol as solvents, under nitrogen protection, react at 50-80℃ for 1-20 hours to obtain 3-(chloromethyl)-4'-methyl-1,1'-biphenyl (intermediate 2), with the following structural formula: ； S3. Finally, allyl chloride, intermediate 2, magnesium granules, and dibromoethane are used as raw materials, and tetrahydrofuran, petroleum ether, or toluene are used as solvents. First, a Grignard reagent was prepared. Then, a mixed solution of intermediate 2 and solvent was added dropwise at a controlled temperature of -20 to 10°C. The reaction was allowed to proceed for 1-15 hours to obtain the final product, 4-(allyl)-4-methyl-1,1'-biphenyl, with the following structural formula: 。 2. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The concentration of toluene in step S1 is 0.5~2 mol / L, and the volume ratio of water to toluene is 1:(2-10).

3. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The mass ratio of p-phenylmethylboric acid, hypochlorous acid, Pd / Cl, and sodium carbonate in step S1 is 1:(1-2):(0.0002-0.01):(0.5-1.5).

4. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The raw material conversion rate in step S1 is 99%.

5. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The concentration of the solvent in S2 is 0.5~2 mol / L; The hydrochloric acid concentration is 20-40%.

6. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The mass ratio of intermediate 1 and hydrochloric acid in S2 is 1:(2-5).

7. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The mass ratio of intermediate 2, allyl chloride, and magnesium granules in S3 is 1:(1.1-3):(1.2-5).

8. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The mass ratio of dibromoethane to intermediate 2 in S3 is (0.005-0.1):

1.

9. The method for preparing a 4-(allyl)-4-methyl-1,1'-biphenyl liquid crystal monomer according to claim 1, characterized in that, The preparation method of the Grignard reagent described in S3 includes: using magnesium particles, dibromoethane, and solvent as substrates, under nitrogen protection, adding a mixture of allyl chloride and solvent to initiate the reaction at a temperature of 10-50℃, then cooling to -20~0℃ after initiation, adding the remaining solution dropwise under controlled temperature, reacting for 1-6 hours, and filtering out excess magnesium particles.

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