A highly efficient green synthesis method and product of liquid crystal monomer

Abstract

The invention discloses a liquid crystal monomer efficient green synthesis method and product, the synthesis method comprises the following steps: S1. in the preparation of biphenyl monomers by Suzuki coupling reaction, or the preparation of ether monomers by Williamson reaction, firstly, the raw materials used for Suzuki coupling reaction or Williamson reaction are added into water, water is used as reaction medium, and stainless steel autoclave is used as reaction equipment; S2. then, the autoclave is sealed, stirring is started, nitrogen is replaced in the stainless steel autoclave, the temperature is increased, after sufficient reaction, the temperature is decreased and the material is discharged, the solid is obtained by suction filtration, and the solid is returned to the stainless steel autoclave; S3. water is added again, stirring is started, the temperature is increased, water is washed, the temperature is decreased, and the liquid crystal monomer product is obtained. The invention is green and environmentally friendly, safe and energy-saving, low in cost, and conducive to industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid crystal monomer synthesis, and in particular to a liquid crystal monomer efficient and green synthesis method and product. Background Art

[0002] In recent years, with the advancement of localization of liquid crystal display materials, liquid crystal displays have been applied to a wider range of fields, and the requirements for the output and quality of mixed liquid crystals are increasing day by day. At the same time, the demand for monomers has increased significantly. Since liquid crystal monomers are organic electronic products, they require a large amount of organic solvents as reaction media. The use of a large amount of organic solvents not only destroys our living environment, but also poses a great safety hazard, which does not meet the requirements of green environmental protection, safety and energy saving.

[0003] Therefore, the applicant selected two types of monomer liquid crystals that account for a relatively large proportion in mixed liquid crystals for research and development: one is to prepare biphenyl monomers using the Suzuki coupling reaction, in which aromatic boric acid or boric acid esters are cross-coupled with chlorine, bromine, or iodine aromatic hydrocarbons under the catalysis of zero-valent palladium; the other is to prepare ether monomers using the Williamson reaction, which are obtained by the reaction of halogenated hydrocarbons or sulfonic acid esters with sodium alcohol or sodium phenol.

[0004] In the synthesis process of monomer liquid crystals, a large amount of organic solvents are used as reaction media, such as toluene, dichloromethane, tetrahydrofuran, etc. The toxicity and difficulty of recycling of organic solvents make them harmful to the environment. Most organic solvents are flammable and explosive, and there are great dangers when using them.

[0005] Therefore, for two types of monomer liquid crystals that account for a relatively large proportion in mixed liquid crystals: one is biphenyl monomers prepared by Suzuki coupling reaction, and the other is ether monomers prepared by Williamson reaction, the applicant has developed and used water as the reaction medium to truly achieve green environmental protection, safety and energy saving. At the same time, a stainless steel autoclave is used for the reaction, which is not limited by the boiling point of the solvent, greatly increases the reaction temperature, increases the reaction speed, and improves the atomic utilization rate, thus the present invention is created.

[0006] The applicant has searched and found no document that discloses the invention of this application. Among them, patent CN114671744A discloses a green method for synthesizing compounds containing biaryl structures by Suzuki coupling reaction. Although green synthesis is also mentioned, a large amount of organic solvents are still used in the reaction system and post-processing process. For example, the organic solvent recorded in its specification is C8-C16 straight-chain or branched alkane. In some embodiments, the organic solvent is C8, C10, C12, C14, C16 normal alkane or isoalkane. In some embodiments, the organic solvent is one or more of isooctadecane, isodecane, isododecane, normal dodecane or isopentadecane, and a large amount of organic solvent is still used as a reaction medium in its synthesis.

[0007] It should be noted that, except for clear patent publications, other information disclosed in the background technology is only intended to increase the understanding of the overall background of the present invention and to understand the background in which the inventor came up with the inventive concept, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0008] In view of this, the purpose of the present invention is to provide a highly efficient and green synthesis method and product of liquid crystal monomers. The synthesis method is green, environmentally friendly, safe and energy-saving, has low cost, and is conducive to industrial production.

[0009] The technical solutions adopted are:

[0010] The present invention provides a highly efficient and green method for synthesizing a liquid crystal monomer, comprising the following steps:

[0011] S1. In the preparation of biphenyl monomers by Suzuki coupling reaction or ether monomers by Williamson reaction, the raw materials for Suzuki coupling reaction or Williamson reaction are first added to water, water is used as the reaction medium, and a stainless steel autoclave is used as the reaction equipment;

[0012] S2. The autoclave is then sealed, stirring is started, the stainless steel autoclave is replaced with nitrogen, the temperature is raised, and after sufficient reaction, the temperature is lowered and the material is discharged, the solid is filtered out, and the solid is returned to the stainless steel autoclave;

[0013] S3. Add water again, start stirring, increase the temperature, wash with water, cool down, and filter again to obtain a liquid crystal monomer product.

[0014] Further, in S1, the raw materials for the Suzuki coupling reaction are propylcyclohexylphenylboric acid, 2,3-difluoro-4-ethoxybromobenzene, potassium carbonate, TBAB and a Pd-based catalyst, or the raw materials are (3-fluoro-4'-propyl-[1,1'-biphenyl]-4-yl)boric acid, 5-bromo-2-(difluoro(3,4,5-trifluorophenoxy)methyl)-1,3-difluorobenzene 3, potassium carbonate and TBAB, or the raw materials are 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl, 3,4,5-trifluorophenylboric acid, potassium carbonate, TBAB and a Pd-based catalyst.

[0015] Further, the amount of raw materials is: 230-260 parts by weight of propylcyclohexylbenzeneboric acid, 230-250 parts by weight of 2,3-difluoro-4-ethoxybromobenzene, 260-290 parts by weight of potassium carbonate, 80-120 parts by weight of TBAB, and 0.05-0.1 parts by weight of Pd catalyst; or the amount of raw materials is: 258g (3-fluoro-4'-propyl-[1,1'-biphenyl]-4-yl)boric acid 240-270 parts by weight, 5-bromo-2-(difluoro(3,4,5-trifluorophenoxy)methyl)-1,3-difluorobenzene 380-400 parts by weight, 260-290 parts by weight of potassium carbonate, TBAB 80-120 parts by weight, and 0.05-0.1 parts by weight of a Pd catalyst; or the raw materials are: 230-260 parts by weight of 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl, 150-190 parts by weight of 3,4,5-trifluorophenylboric acid, 260-290 parts by weight of potassium carbonate, 80-120 parts by weight of TBAB, and 0.05-0.1 parts by weight of a Pd catalyst.

[0016] Furthermore, the Pd-based catalyst is Pd-132.

[0017] Further, in S1, the raw materials for the Williamson reaction are (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 4-ethoxy-2,3-difluorophenol, potassium carbonate and TBAB; or the raw materials are 4-(bromodifluoromethyl)-2',3,5-trifluoro-4"-propyl-1,1':4',1"-triphenyl, 3,4,5-trifluorophenol, potassium carbonate and TBAB.

[0018] Further, the amount of raw materials is: 300-320 parts by weight of (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 150-190 parts by weight of 4-ethoxy-2,3-difluorophenol, 260-290 parts by weight of potassium carbonate, and 80-120 parts by weight of TBAB, or the raw material is 227g of 4-(bromodifluoromethyl)-2',3,5-trifluoro-4"-propyl-1,1':4',1"-triphenyl, 210-230 parts by weight, 3,4,5-trifluorophenol, 60-80 parts by weight, 120-140 parts by weight of potassium carbonate, and 70-100 parts by weight of TBAB.

[0019] Furthermore, in S2, the temperature is raised to 100-160°C, and after sufficient reaction, the temperature is lowered to 35-55°C for discharge.

[0020] More preferably, in S2, the temperature is raised to 110-150°C, and after sufficient reaction, the temperature is lowered to 35-55°C for discharging. The temperature is raised to 110-150°C, for example, 110°C, 120°C, 130, 140°C or 150°C, and further preferably raised to 120-130°C; the temperature is lowered to 35-55°C, for example, 35°C, 45°C or 55°C.

[0021] Further, in S3, the temperature is raised to 75-95°C, washed with water, and cooled to 35-65°C. The temperature is raised to 75-95°C, for example, raised to 75°C, 85°C or 95°C, and cooled to 35-65°C, for example, 35°C, 45°C, 55°C or 65°C.

[0022] Furthermore, the efficient and green synthesis method of liquid crystal monomers also includes S4. The filtrate obtained by filtration is retained for the next batch reaction.

[0023] A liquid crystal monomer product of the present invention is prepared by any of the above-mentioned synthesis methods.

[0024] The beneficial effects of the present invention are:

[0025] In the first aspect, the present invention uses water as a reaction medium, which is green, environmentally friendly, safe, energy-saving and has low cost.

[0026] In the second aspect, the present invention uses a stainless steel autoclave as a reaction device, which can greatly increase the reaction temperature, increase the reaction speed, improve the atomic utilization rate, and improve the yield. The sealed autoclave reduces heat loss and is more energy-efficient. The reaction is stable and is conducive to industrial production.

[0027] Thirdly, the post-treatment water phase of the present invention is directly applied in the reaction to reduce wastewater discharge. The post-treatment is achieved by heating and cooling the water system, avoiding the use of a large amount of organic solvents, being green, environmentally friendly, safe, energy-saving, and having a low economic cost. DETAILED DESCRIPTION

[0028] The present invention is described in detail below through specific examples and comparative examples, but the use and purpose of these exemplary implementation modes are only used to illustrate the present invention, and do not constitute any form of limitation on the actual protection scope of the present invention, nor limit the protection scope of the present invention to these.

[0029] In the embodiments and comparative examples of the present invention, Pd-132 is bis(di-tert-butyl-4-dimethylaminophosphine)palladium chloride, the molecular formula of which is C 32 H 56 Cl2N2P2Pd. TBAB is tetrabutylammonium bromide, with a molecular formula of C 16 H 36 BrN.

[0030] The raw materials used in the following examples and comparative examples can all be purchased from the market. The purity test adopts a GC test instrument. The GC test instrument is a gas chromatograph. According to the product manual of the gas chromatograph, the purity of the product is tested by a conventional method in the art and expressed as GC purity.

[0031] Example 1 Suzuki coupling reaction

[0032] The present embodiment provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0033] 246g of propylcyclohexylbenzene boronic acid, 237g of 2,3-difluoro-4-ethoxybromobenzene, 276g of potassium carbonate, 1230g of water, 100g of TBAB, 0.07g of catalyst Pd-132 were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 110°C. After the reaction was timed for 2 hours, the temperature was lowered to 35°C, the material was discharged, and 370g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g of water was added, stirring was started, the temperature was raised to 70°C, washed with water for 30 minutes, cooled to 35°C, filtered again, and the filtrate was reserved for the next batch reaction. Reduce wastewater discharge, weigh the filter cake to obtain 362g of white solid, dry to obtain 341g, the yield is 95%, and the GC purity is 99.910%.

[0034] The reaction formula is as follows:

[0035]

[0036] Example 2 Suzuki coupling reaction

[0037] The present embodiment provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0038] In a 2000 ml stainless steel autoclave, 258 g (3-fluoro-4'-propyl-[1,1'-biphenyl]-4-yl)boric acid, 389 g 5-bromo-2-(difluoro(3,4,5-trifluorophenoxy)methyl)-1,3-difluorobenzene, 276 g potassium carbonate, 1290 g water, 100 g TBAB, and 0.07 g of catalyst Pd-132 were added. The autoclave was sealed and stirred. After nitrogen replacement in the autoclave, the temperature was raised to 110°C, and the reaction was timed for 2 hours. Then, the temperature was lowered to 45°C, the material was discharged, and 550 g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000 g of water was added, stirring was started, the temperature was raised to 90°C, washed with water for 30 minutes, cooled to 45°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 520 g of a white solid, which was dried to obtain 482 g, with a yield of 96% and a GC purity of 99.901%.

[0039] The reaction formula is as follows:

[0040]

[0041] Example 3 Suzuki coupling reaction

[0042] The present embodiment provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0043] 248.5g 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl, 176g 3,4,5-trifluorophenylboric acid, 276g potassium carbonate, 1240g water, 100g TBAB, 0.07g catalyst Pd-132 were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 120°C. After the reaction was timed for 2 hours, the temperature was lowered to 45°C, the material was discharged, and 371g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g water was added, stirring was started, the temperature was raised to 75°C, washed with water for 30 minutes, cooled to 45°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 362g of white solid, and 330g was obtained by drying, with a yield of 96% and a GC purity of 99.905%.

[0044] The reaction formula is as follows:

[0045]

[0046] Comparative Example 1

[0047] The present comparative example provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0048] 248.5g 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl, 176g 3,4,5-trifluorophenylboric acid, 276g potassium carbonate, 1240g water, 100g TBAB, 0.07g catalyst Pd-132 were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 70°C. After the reaction was timed for 2 hours, the temperature was lowered to 55°C, the material was discharged, and 251g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g water was added, stirring was started, the temperature was raised to 75°C, washed with water for 30 minutes, cooled to 55°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 207g of white solid, and 192g was obtained by drying, with a yield of 56% and a GC purity of 98.105%.

[0049] Compared with Example 3, the first heating in Comparative Example 1 was 70° C., while the first heating in Example 3 was 120° C. It can be seen that the first heating to 120° C. can improve the yield.

[0050] Example 4 Williamson etherification reaction

[0051] The present embodiment provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0052] 316g (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 174g 4-ethoxy-2,3-difluorophenol, 276g potassium carbonate, 1440g water, 100g TBAB were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 130°C. After timing the reaction for 2 hours, the temperature was lowered to 55°C, the material was discharged, and 457g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g water was added, stirring was started, the temperature was raised to 85°C, washed with water for 30 minutes, cooled to 55°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 400g of white solid, and 376g was obtained by drying, with a yield of 96.5% and a GC purity of 99.873%.

[0053] The reaction formula is as follows:

[0054]

[0055] Comparative Example 2

[0056] The present comparative example provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0057] 316g (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 174g 4-ethoxy-2,3-difluorophenol, 276g potassium carbonate, 1440g water, 100g TBAB were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 80°C. After the reaction was timed for 2 hours, the temperature was lowered to 55°C, the material was discharged, and 402g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g water was added, stirring was started, the temperature was raised to 85°C, washed with water for 30 minutes, cooled to 55°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 310g of white solid, and 283g was obtained by drying, with a yield of 72% and a GC purity of 98.771%.

[0058] Compared with Example 4, the first heating in Comparative Example 2 was 130° C., while the first heating in Example 4 was 80° C. It can be seen that the first heating to 130° C. can improve the yield.

[0059] Example 5 Williamson etherification reaction

[0060] The present embodiment provides a highly efficient and green synthesis method of a liquid crystal monomer, comprising the following steps:

[0061] 227g 4-(bromodifluoromethyl)-2',3,5-trifluoro-4"-propyl-1,1':4',1"-triphenyl, 74g 3,4,5-trifluorophenol, 138g potassium carbonate, 1200g water, 80g TBAB were added to a 2000ml stainless steel autoclave, the autoclave was sealed, stirring was started, the autoclave was replaced with nitrogen, and the temperature was raised to 140°C. After the reaction was timed for 2 hours, the temperature was lowered to 65°C, the material was discharged, and 313g of white solid was obtained by suction filtration. The white solid was returned to the autoclave, 1000g water was added, stirring was started, the temperature was raised to 95°C, washed with water for 30 minutes, cooled to 65°C, filtered again, and the filtrate was reserved for the next batch reaction to reduce wastewater discharge. The filter cake was weighed to obtain 285g of white solid, which was dried to obtain 251g, with a yield of 96.2% and a GC purity of 99.913%.

[0062] The reaction formula is as follows:

[0063]

[0064] The series of detailed descriptions listed above are only specific descriptions of feasible embodiments of the present invention. They are not intended to limit the scope of protection of the present invention. All equivalent embodiments or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing a liquid crystal monomer, characterized in that: The steps include: S1. In the preparation of biphenyl monomers by Suzuki coupling reaction or ether monomers by Williamson reaction, the raw materials for Suzuki coupling reaction or Williamson reaction are first added to water, water is used as the reaction medium, and a stainless steel autoclave is used as the reaction equipment; The raw materials for the Suzuki coupling reaction are propylcyclohexylphenylboric acid, 2,3-difluoro-4-ethoxybromobenzene, potassium carbonate, TBAB and a Pd-based catalyst, or the raw materials are (3-fluoro-4'-propyl-[1,1'-biphenyl]-4-yl)boric acid, 5-bromo-2-(difluoro(3,4,5-trifluorophenoxy)methyl)-1,3-difluorobenzene, potassium carbonate, TBAB and a Pd-based catalyst, or the raw materials are 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl, 3,4,5-trifluorophenylboric acid, potassium carbonate, TBAB and a Pd-based catalyst; The amount of raw materials used is: 230-260 parts by weight of propylcyclohexylbenzeneboric acid, 230-250 parts by weight of 2,3-difluoro-4-ethoxybromobenzene, 260-290 parts by weight of potassium carbonate, 80-120 parts by weight of TBAB, and 0.05-0.1 parts by weight of Pd catalyst; or the amount of raw materials used is: 240-270 parts by weight of (3-fluoro-4'-propyl-[1,1'-biphenyl]-4-yl)boric acid, 380-400 parts by weight of 5-bromo-2-(difluoro(3,4,5-trifluorophenoxy)methyl)-1,3-difluorobenzene, 260-290 parts by weight of potassium carbonate, TBAB 80-120 parts by weight, Pd catalyst is 0.05-0.1 parts by weight; or the raw materials are: 4-chloro-3-fluoro-4'-propyl-1,1'-biphenyl 230-260 parts by weight, 3,4,5-trifluorophenylboric acid 150-190 parts by weight, potassium carbonate 260-290 parts by weight, TBAB 80-120 parts by weight, Pd catalyst is 0.05-0.1 parts by weight; The raw materials for the Williamson reaction are (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 4-ethoxy-2,3-difluorophenol, potassium carbonate and TBAB; or the raw materials are 4-(bromodifluoromethyl)-2',3,5-trifluoro-4''-propyl-1,1':4',1''-triphenyl, 3,4,5-trifluorophenol, potassium carbonate and TBAB; The raw material dosage is: 300-320 parts by weight of (4'-propyl-[1,1'-bis(cyclohexane)]-4-yl)methyl methanesulfonate, 150-190 parts by weight of 4-ethoxy-2,3-difluorophenol, 260-290 parts by weight of potassium carbonate, and 80-120 parts by weight of TBAB, or the raw material is 210-230 parts by weight of 4-(bromodifluoromethyl)-2',3,5-trifluoro-4''-propyl-1,1':4',1''-triphenyl, 60-80 parts by weight of 3,4,5-trifluorophenol, 120-140 parts by weight of potassium carbonate, and 70-100 parts by weight of TBAB; S2. The autoclave is then sealed, stirring is started, the stainless steel autoclave is replaced with nitrogen, the temperature is raised to 100-160 ° C, and after sufficient reaction, the temperature is lowered to 35-55 ° C. The solid is filtered and returned to the stainless steel autoclave; S3. Add water again, start stirring, raise the temperature to 75-95°C, wash with water, cool down to 35-65°C, filter again, and obtain the liquid crystal monomer product.

2. The method for synthesizing a liquid crystal monomer according to claim 1, characterized in that: The Pd-based catalyst is Pd-132.

3. The method for synthesizing a liquid crystal monomer according to claim 1, characterized in that: It also includes S4. The filtrate obtained by filtration is reserved for the next batch reaction.

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