A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate

Abstract

The present application relates to the technical field of organic chemistry, and specifically discloses a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, comprising the following steps: adding 2,4-dimethyl-3-pentanol to a solvent, stirring evenly, cooling to (-30°C)-(-10°C), adding a modified catalyst while stirring, keeping warm and stirring, then heating to (-10)-(10)°C, adding methacryloyl chloride, returning to room temperature after the end of the insulation reaction, adding a functionalized polymerization inhibitor, continuing to stir, quenching, separating the liquids, and distilling to obtain high-purity 2,4-dimethylpentyl-3-yl-methacrylate. The present application adds a modified catalyst and a functionalized polymerization inhibitor. The modified catalyst can not only exert the catalytic effect of the "active lithium" thereon, but also has the stability of the benzene ring. The functionalized polymerization inhibitor contains a phenolic structure and multiple benzene ring structures, thereby improving the purity and yield of the product.

Description

Technical Field

[0001] The present invention relates to the field of organic chemistry, and more particularly to a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate. Background Art

[0002] 2,4-dimethylpentan-3-ylmethacrylate (CAS No. 4.104050-87-5) is a methacrylate compound that has a wide range of industrial applications.

[0003] As a methacrylate monomer, it can be used to synthesize various polymers, including plastics, rubbers, and synthetic fibers; in the coatings industry, this compound may be used to make high-performance coatings that provide specific physical and chemical properties, such as durability, weather resistance, and gloss; in adhesive manufacturing, it can be used as a tackifier or cross-linking agent to improve the bonding strength and temperature resistance of adhesives; in composite materials, it can be used as a matrix resin for reinforcing materials to improve the overall performance of composite materials; as an intermediate for the synthesis of other complex organic compounds, it is used in the pharmaceutical, fragrance, dye, and other industries. Its purity has a significant impact on the synthesis of back-end materials and directly affects product performance.

[0004] The prior art (US2129663A) uses a high temperature state for the synthesis of such compounds, and the yield of the obtained product is not high. At the same time, no relevant description is made on the purity of the product. At the same time, the catalyst n-butyl lithium commonly used in the prior art has many side reactions during the reaction process, which not only leads to a decrease in the yield of the target product, but also is difficult to remove in the subsequent process.

[0005] Therefore, it is particularly important to develop a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate. Summary of the invention

[0006] The main technical problem solved by the present invention is a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, which uses low temperature to prepare high-purity target products and is suitable for process scale-up production.

[0007] The present invention specifically relates to a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, comprising the following steps: Add 2,4-dimethyl-3-pentanol to the solvent, stir evenly, cool to (-30°C) - (-10°C), add the modified catalyst while stirring, keep warm and stir for 0.5-1h, then heat to (-10) - (10)°C, add methacryloyl chloride, keep warm and react for 0.3-1h. After the reaction is completed, return to room temperature, add the functionalized inhibitor, continue stirring for 16-22min, quench the reaction solution, separate the liquid, and then distill to obtain high-purity 2,4-dimethylpentanyl-3-yl-methacrylate, wherein the molar ratio of 2,4-dimethyl-3-pentanol, modified catalyst, methacryloyl chloride and functionalized inhibitor is 1: (1.0-1.35): (1.0-1.5): (0.001-0.003).

[0008] Preferably, the solvent can be selected from at least one of tetrahydrofuran, dichloromethane and toluene.

[0009] Preferably, the modified catalyst is prepared by the following steps: Add n-butyl lithium to cyclohexane, stir evenly, and under anhydrous and oxygen-free conditions, dropwise add a mixture of 1,1-diphenylethylene and cyclohexane, and control the dripping to be completed within 10 minutes. After the dripping is completed, heat to 34-42°C, continue to stir and react for 52-64 hours to obtain a modified catalyst, wherein the mass ratio of n-butyl lithium, cyclohexane and the mixture a is 2-3:40-50:16-20, and the mass ratio of 1-diphenylethylene and cyclohexane in the mixture a is 6.2-9.4:20-30. In the above reaction process, cyclohexane is used as a solvent, and n-butyl lithium and 1-diphenylethylene undergo an addition reaction to obtain a modified catalyst.

[0010] Preferably, the functionalized polymerization inhibitor is prepared by the following steps: Step A1, add p-hydroxybenzoic acid and diethylenetriamine to anhydrous DMF, stir evenly, and drop a mixture b of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After the dropping, heat to 62-66°C, stir and react for 3-5h. After the reaction is completed, filter, wash and dry to obtain a diamino monomer, wherein the mass ratio of p-hydroxybenzoic acid, diethylenetriamine, anhydrous DMF and mixture b is 4.2-5.6:3. 2-4.0:60-80:32-44, in the mixed solution b, the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is 5.8-7.4:4.0-4.4:26-30, in the above reaction process, anhydrous DMF is used as solvent, N,N-dicyclohexylcarbodiimide is used as dehydrating agent, 4-dimethylaminopyridine is used as acylating agent, p-hydroxybenzoic acid and diethylenetriamine undergo amidation reaction to obtain a diamino monomer; Step A2, adding the diamino monomer and potassium carbonate to anhydrous DMF, stirring evenly, then adding 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, heating to 52-56° C., continuing stirring to react for 8-12 hours, and concentrating under reduced pressure to obtain a functionalized polymerization inhibitor, wherein the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 3.6-4.2: 0.06-0.08: 65-75: 4.0-4.4. In the above reaction process, potassium carbonate is used as a base catalyst, and the amino group on the diamino monomer undergoes a nucleophilic substitution reaction with the active acyl chloride group of 3,5-di-tert-butyl-4-hydroxybenzoyl chloride to obtain a functionalized polymerization inhibitor.

[0011] Preferably, the distillation reaction is performed by vacuum distillation with a pressure range of 150Pa-200Pa.

[0012] In summary, this application has the following beneficial effects: 1. The present invention uses 2,4-dimethyl-3-pentanol as a raw material, interacts with a modified catalyst and methacryloyl chloride at low temperature, and adds a functionalized polymerization inhibitor after the reaction to prevent the molecules from polymerizing each other, thereby preparing a high-purity target product. The reaction operation steps are simple and suitable for process scale-up production.

[0013] 2. In order to improve the purity and yield of 2,4-dimethylpentanyl-3-yl-methacrylate, the present invention adds a modified catalyst and a functionalized inhibitor. The modified catalyst is prepared by addition reaction of n-butyl lithium and 1,1-diphenylethylene. The prepared modified catalyst can not only exert the catalytic effect of the "active lithium" thereon, but also has the stability of the benzene ring, thereby avoiding the traditional n-butyl lithium having many side reactions during the catalytic reaction, resulting in a reduced yield of the target product. The functionalized inhibitor contains a phenolic structure, which can not only play an inhibitory role, but also contains multiple benzene ring structures, which can produce π-π interactions with the rigid rings on the modified catalyst, making the modified catalyst and the functionalized inhibitor easier to be removed during post-treatment, thereby further improving the purity and yield of 2,4-dimethylpentanyl-3-yl-methacrylate. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0015] Figure 11H NMR spectrum of the target product in Example 1 of the present application; Figure 2 This is the GC spectrum of the target product in Example 1 of the present application (the upper figure is the GC spectrum of the target product within 0-35 min, and the lower figure is a partially enlarged GC spectrum of the target product within 8-30 min). DETAILED DESCRIPTION

[0016] In order to make the implementation methods of the present application easier to understand, the present application will be described in detail below in conjunction with specific examples. These examples are only for illustration and are not limited to the scope of application of the present application.

[0017] In the examples and comparative examples, the purity and yield of FDCA were detected by high performance liquid chromatography.

[0018] Preparation Example 1-3 provides a method for preparing a modified catalyst.

[0019] Preparation Example 1 This preparation example provides a modified catalyst, which is prepared by the following steps: Add n-butyl lithium to cyclohexane, stir at a speed of 550 rpm for 24 minutes until uniform, and add a mixed solution a of 1,1-diphenylethylene and cyclohexane dropwise under anhydrous and oxygen-free conditions. The dripping is controlled to be completed within 10 minutes. After the dripping is completed, the temperature is raised to 34°C, the speed is maintained unchanged, and the stirring reaction is continued for 52 hours to obtain a modified catalyst, wherein the mass ratio of n-butyl lithium, cyclohexane and mixed solution a is 2:40:16, and the mass ratio of 1-diphenylethylene and cyclohexane in the mixed solution a is 6.2:20.

[0020] Preparation Example 2 This preparation example provides a modified catalyst, which is prepared by the following steps: Add n-butyl lithium to cyclohexane, stir at a speed of 600 rpm for 28 minutes until uniform, and under water and oxygen-free conditions, add a mixed solution a of 1,1-diphenylethylene and cyclohexane dropwise, and control the dripping to be completed within 10 minutes. After the dripping is completed, the temperature is raised to 38°C, the speed is maintained unchanged, and the stirring reaction is continued for 58 hours to obtain a modified catalyst, wherein the mass ratio of n-butyl lithium, cyclohexane and mixed solution a is 2.5:45:18, and the mass ratio of 1-diphenylethylene and cyclohexane in the mixed solution a is 7.8:25.

[0021] Preparation Example 3 This preparation example provides a modified catalyst, which is prepared by the following steps: Add n-butyl lithium to cyclohexane, stir at a speed of 650 rpm for 32 minutes until uniform, and under water and oxygen-free conditions, add dropwise a mixed solution a of 1,1-diphenylethylene and cyclohexane, and control the dripping to be completed within 10 minutes. After the dripping is completed, raise the temperature to 42°C, maintain the speed unchanged, and continue stirring to react for 64 hours to obtain a modified catalyst, wherein the mass ratio of n-butyl lithium, cyclohexane and mixed solution a is 3:50:20, and the mass ratio of 1-diphenylethylene and cyclohexane in the mixed solution a is 9.4:30.

[0022] Preparation Examples 4-6 and Comparative Preparation Example 1 provide a method for preparing a functionalized polymerization inhibitor.

[0023] Preparation Example 4 This preparation example provides a functionalized polymerization inhibitor, which is prepared by the following steps: Step A1, adding p-hydroxybenzoic acid and diethylenetriamine to anhydrous DMF, stirring at a speed of 620 rpm for 18 minutes until uniform, and dropping a mixed solution b of N, N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring, raising the temperature to 62°C, stirring and reacting for 3 hours, and after the reaction is completed, filtering with suction, washing the filter cake with anhydrous ethanol and deionized water for 3 times, and drying at 64°C to constant weight to obtain a diamino monomer, wherein the mass ratio of p-hydroxybenzoic acid, diethylenetriamine, anhydrous DMF and mixed solution b is 4.2:3.0:60:32, and the mass ratio of N, N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF in the mixed solution b is 5.8:4.0:26; Step A2, adding the diamino monomer and potassium carbonate to anhydrous DMF, stirring at a speed of 700 rpm for 24 minutes until uniform, then adding 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, heating to 52° C., continuing to stir and react for 8 hours, concentrating under reduced pressure, removing anhydrous DMF, and obtaining a functionalized polymerization inhibitor, wherein the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 3.6:0.06:65:4.0.

[0024] Preparation Example 5 This preparation example provides a functionalized polymerization inhibitor, which is prepared by the following steps: Step A1, adding p-hydroxybenzoic acid and diethylenetriamine to anhydrous DMF, stirring at a rotation speed of 660rpm for 22min until uniform, and dropping a mixed solution b of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring, raising the temperature to 64°C, stirring and reacting for 4h, after the reaction is completed, suction filtering, washing the filter cake with anhydrous ethanol and deionized water for 4 times, and drying at 68°C to constant weight to obtain a diamino monomer, wherein the mass ratio of p-hydroxybenzoic acid, diethylenetriamine, anhydrous DMF and mixed solution b is 4.9:3.6:70:38, and the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF in the mixed solution b is 6.6:4.2:28; Step A2, adding the diamino monomer and potassium carbonate to anhydrous DMF, stirring at a rotation speed of 740 rpm for 24 minutes until uniform, then adding 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, heating to 54° C., continuing to stir and react for 10 hours, concentrating under reduced pressure, removing anhydrous DMF, and obtaining a functionalized polymerization inhibitor, wherein the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 3.9:0.07:70:4.2.

[0025] Preparation Example 6 This preparation example provides a functionalized polymerization inhibitor, which is prepared by the following steps: Step A1, adding p-hydroxybenzoic acid and diethylenetriamine to anhydrous DMF, stirring at a speed of 700 rpm for 26 minutes until uniform, and dropping a mixed solution b of N, N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring, raising the temperature to 66°C, stirring and reacting for 5 hours, and after the reaction is completed, filtering with suction, washing the filter cake with anhydrous ethanol and deionized water for 5 times, and drying at 72°C to constant weight to obtain a diamino monomer, wherein the mass ratio of p-hydroxybenzoic acid, diethylenetriamine, anhydrous DMF and mixed solution b is 5.6:4.2:80:44, and the mass ratio of N, N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF in the mixed solution b is 7.4:4.4:30; Step A2, adding the diamino monomer and potassium carbonate to anhydrous DMF, stirring at a rotation speed of 740 rpm for 24 minutes until uniform, then adding 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, raising the temperature to 56°C, continuing to stir and react for 12 hours, and concentrating under reduced pressure to remove anhydrous DMF to obtain a functionalized inhibitor, wherein the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 4.2:0.08:75:4.4.

[0026] Comparative Preparation Example 1 This comparative preparation example provides a functionalized polymerization inhibitor, which is prepared by the following steps: Step A1, add glycolic acid and diethylenetriamine to anhydrous DMF, stir at a speed of 620rpm for 18min until uniform, and add a mixed solution b of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After the addition is completed, the temperature is raised to 62°C, and the reaction is stirred for 3h. After the reaction is completed, the filter is filtered, and the filter cake is washed with anhydrous ethanol and deionized water for 3 times, and dried at 64°C to constant weight to obtain a diamino monomer, wherein the mass ratio of glycolic acid, diethylenetriamine, anhydrous DMF and mixed solution b is 4.2:3.0:60:32, and the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF in the mixed solution b is 5.8:4.0:26; Step A2, adding the diamino monomer and potassium carbonate to anhydrous DMF, stirring at a speed of 700 rpm for 24 minutes until uniform, then adding 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, heating to 52° C., continuing to stir and react for 8 hours, concentrating under reduced pressure, removing anhydrous DMF, and obtaining a functionalized polymerization inhibitor, wherein the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 3.6:0.06:65:4.0.

[0027] Examples 1-3 and Comparative Examples 1-4 provide a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate.

[0028] Example 1 This embodiment provides a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, comprising the following steps: Synthesis: 4-dimethyl-3-pentanol (300 g, 2.1 mol, 1.0 eq) was added to tetrahydrofuran (1800 mL, 6 v), stirred and cooled to -20 ° C, and the modified catalyst prepared in Preparation Example 1 (2.205 mol, 1.05 eq) was added. The dropwise addition time was about 2 h. After the dropwise addition was completed, the mixture was kept at -20 ° C and stirred for 0.5 h. The reaction solution was then heated to -5 ° C, and methacryloyl chloride (319 g, 2.205 mol, 1.05 eq) was added. At this time, the temperature of the reaction solution was observed to fluctuate, and the solution began to turn light green. The dropwise addition speed was controlled to keep the temperature of the reaction solution no more than 10 ° C. The total dropwise addition time was about 0.5 h. After the mixture was kept at -5 ° C and stirred for 0.5 h, the reaction was terminated. The functionalized inhibitor (10.16 g, 1%) prepared in Preparation Example 4 was added. Post-treatment: at 5±10°C, water (1000 mL) was added dropwise to quench, and then the mixture was allowed to stand for separation to separate the lower aqueous layer. The upper organic layer I was extracted three times with 1.2L water (1200 mL, 4V), and the four aqueous layers were combined. The combined aqueous layer was extracted with dichloromethane 1 (800 mL, 2.3V), and the mixture was allowed to stand for separation to separate the organic layer II. The organic layers I and II were combined, and the organic layer was dried and concentrated over anhydrous sodium sulfate, and distilled (vacuum 184 pa, low temperature 52°C, top temperature 40°C) to obtain the target product 2,4-dimethylpentyl-3-yl-methylacrylate.

[0029] Example 2 This embodiment provides a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, comprising the following steps: Synthesis: 4-dimethyl-3-pentanol (300 g, 2.1 mol, 1.0 eq) was added to tetrahydrofuran (1800 mL, 6 v), stirred and cooled to -20 ° C, and the modified catalyst prepared in Preparation Example 2 (2.73 mol, 1.3 eq) was added. The dropwise addition time was about 2.1 h. After the dropwise addition was completed, the mixture was kept at -20 ° C and stirred for 0.6 h. The reaction solution was then heated to -5 ° C, and methacryloyl chloride (394.95 g, 2.73 mol, 1.3 eq) was added. At this time, the temperature of the reaction solution was observed to fluctuate, and the solution began to turn light green. The dropwise addition speed was controlled to keep the temperature of the reaction solution no more than 10 ° C. The total dropwise addition time was about 0.5 h. After the mixture was kept at -5 ° C and stirred for 0.5 h, the reaction was completed. The functionalized inhibitor (10.16 g, 1%) prepared in Preparation Example 5 was added. Post-treatment: at 5±10°C, water (1000 mL) was added dropwise to quench, and then the mixture was allowed to stand for separation to separate the lower aqueous layer. The upper organic layer I was extracted three times with 1.2L water (1200 mL, 4V), and the four aqueous layers were combined. The combined aqueous layer was extracted with dichloromethane 1 (800 mL, 2.3V), and the mixture was allowed to stand for separation to separate the organic layer II. The organic layers I and II were combined, and the organic layer was dried and concentrated over anhydrous sodium sulfate, and distilled (vacuum 184 pa, low temperature 52°C, top temperature 40°C) to obtain the target product 2,4-dimethylpentyl-3-yl-methylacrylate.

[0030] Example 3 This embodiment provides a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, comprising the following steps: Synthesis: 4-dimethyl-3-pentanol (300 g, 2.1 mol, 1.0 eq) was added to toluene (1800 mL, 6 v), stirred and cooled to -20 ° C, and the modified catalyst prepared in Preparation Example 3 (2.205 mol, 1.05 eq) was added, and the mixture was kept at -10 ° C and stirred for 0.5 h. The reaction solution was then heated to -5 ° C, and methacryloyl chloride (319 g, 2.205 mol, 1.05 eq) was added. At this time, the temperature of the reaction solution was observed to fluctuate, and the solution began to turn light green. The dripping speed was controlled to keep the temperature of the reaction solution no more than 10 ° C. The total dripping time was about 0.5 h, and the mixture was kept at -5 ° C and stirred for 0.5 h. After the reaction was completed, the functionalized inhibitor (10.16 g, 1%) prepared in Preparation Example 6 was added; Post-treatment: at 5±10°C, water (1000 mL) was added dropwise to quench, and then the mixture was allowed to stand for separation to separate the lower aqueous layer. The upper organic layer I was extracted three times with 1.2L water (1200 mL, 4V), and the four aqueous layers were combined. The combined aqueous layer was extracted with dichloromethane 1 (800 mL, 2.3V), and the mixture was allowed to stand for separation to separate the organic layer II. The organic layers I and II were combined, and the organic layer was dried and concentrated over anhydrous sodium sulfate, and distilled (vacuum 184 pa, low temperature 52°C, top temperature 40°C) to obtain the target product 2,4-dimethylpentyl-3-yl-methylacrylate.

[0031] Comparative Example 1 This comparative example provides a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate. Compared with Example 1, the order of adding materials is changed from "adding modified catalyst (2.205 mol, 1.05 eq), the dropwise addition time is about 2 h, after the dropwise addition is completed, keeping -10 ° C and stirring for 0.5 h, then heating the reaction solution to -5 ° C, and then adding methacryloyl chloride (319 g, 2.205 mol, 1.05 eq)" to "modified catalyst (2.205 mol, 1.05 eq) and methacryloyl chloride (319 g, 2.205 mol, 1.05 eq) are mixed and then added dropwise. Specifically: Synthesis: 4-dimethyl-3-pentanol (300 g, 2.1 mol, 1.0 eq) was added to tetrahydrofuran (1800 mL, 6 v), stirred and cooled to -20 ° C, and a mixed solution of modified catalyst (2.205 mol, 1.05 eq) and methacryloyl chloride (319 g, 2.205 mol, 1.05 eq) was added. The addition time was about 2 h. After the addition was completed, the mixture was kept at -20 ° C and stirred for 0.5 h. The reaction solution was then heated to -5 ° C. At this time, the color of the reaction solution was observed to change slightly. After keeping at -5 ° C and stirring for 0.5 h, the reaction was completed, and the functionalized inhibitor (10.16 g, 1%) prepared in Preparation Example 4 was added.

[0032] Post-treatment: at 5±10°C, water (1000 mL) was added dropwise to quench, and the mixture was allowed to stand for separation to separate the lower aqueous layer. The upper organic layer I was extracted three times with 1.2 L of water (1200 mL, 4 V), and the four aqueous layers were combined. The combined aqueous layer was extracted with dichloromethane 1 (800 mL, 2.3 V), and the mixture was allowed to stand for separation to separate the organic layer II. The organic layers I and II were combined, and the organic layer was dried and concentrated over anhydrous sodium sulfate, and distilled (vacuum 184 pa, low temperature 52°C, top temperature 40°C) to obtain the target product 2,4-dimethylpentyl-3-yl-methylacrylate.

[0033] Comparative Example 2 This comparative example provides a method for preparing high-purity 2,4-dimethylpentanyl-3-yl-methacrylate. Compared with Example 1, the step of "adding a functional inhibitor (3 g, 1%)" is eliminated, and the other steps remain unchanged. After post-treatment, the target product 2,4-dimethylpentanyl-3-yl-methacrylate is obtained.

[0034] Comparative Example 3 This comparative example provides a method for preparing high-purity 2,4-dimethylpentanyl-3-yl-methacrylate. Compared with Example 1, the modified catalyst in Example 1 is replaced with n-butyl lithium, and the other steps remain unchanged. After post-treatment, the target product 2,4-dimethylpentanyl-3-yl-methacrylate is obtained.

[0035] Comparative Example 4 This comparative example provides a method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate. Compared with Example 1, the modified catalyst in Example 1 is replaced by the modified catalyst in Comparative Preparation Example 1. The remaining steps remain unchanged, and the target product 2,4-dimethylpentyl-3-yl-methacrylate is obtained through post-treatment. Specifically: Synthesis: 4-dimethyl-3-pentanol (300 g, 2.1 mol, 1.0 eq) was added to tetrahydrofuran (1800 mL, 6 v), stirred and cooled to -20 ° C, and the modified catalyst prepared in Preparation Example 1 (2.205 mol, 1.05 eq) was added. The dropwise addition time was about 2 h. After the dropwise addition was completed, the mixture was kept at -20 ° C and stirred for 0.5 h. The reaction solution was then heated to -5 ° C, and methacryloyl chloride (319 g, 2.205 mol, 1.05 eq) was added. At this time, the temperature of the reaction solution was observed to fluctuate, and the solution began to turn light green. The dropwise addition speed was controlled to keep the temperature of the reaction solution no more than 10 ° C. The total dropwise addition time was about 0.5 h. After the mixture was kept at -5 ° C and stirred for 0.5 h, the reaction was terminated. The functionalized inhibitor (3 g, 1%) prepared in Comparative Preparation Example 1 was added. Post-treatment: at 5±10°C, water (1000 mL) was added dropwise to quench, and then the mixture was allowed to stand for separation to separate the lower aqueous layer. The upper organic layer I was extracted three times with 1.2L water (1200 mL, 4V), and the four aqueous layers were combined. The combined aqueous layer was extracted with dichloromethane 1 (800 mL, 2.3V), and the mixture was allowed to stand for separation to separate the organic layer II. The organic layers I and II were combined, and the organic layer was dried and concentrated over anhydrous sodium sulfate, and distilled (vacuum 184 pa, low temperature 52°C, top temperature 40°C) to obtain the target product 2,4-dimethylpentyl-3-yl-methylacrylate.

[0036] Performance Testing The yield calculation formula is: Yield (%) = (Mole of product (mmol)) / (Mole of fructose (mmol)) × 100%. The purity is determined by the liquid phase area normalization method, and the yield is determined by the standard curve method after characterizing the standard product.

[0037] The high performance liquid chromatography detector used was Hitachi L2000 HPLC System, Alltech C18 column; the mobile phase was 0.5 wt% methanol and trifluoroacetic acid aqueous solution, with a mass ratio of 20:80; flow rate: 1.0 mL / min, column temperature: 30°C, detector: DAD, detection wavelength: 284 nm.

[0038] The above-mentioned test method was used to detect the purity and yield of 2,4-dimethylpentyl-3-yl-methacrylate in Examples 1-3 and Comparative Examples 1-4 in turn by high performance liquid chromatography. The specific test data are shown in Table 1 below: Table 1 Yield and purity test of 2,4-dimethylpentyl-3-yl-methacrylate

[0039] Combining Table 1 and Figure 1-2 It can be seen that compared with Example 1-4, the 2,4-dimethylpentyl-3-yl-methacrylate prepared in Example 1-3 has higher purity and yield.

[0040] This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. After reading this specification, those skilled in the art can make non-creative modifications to this embodiment as needed, but as long as it is within the scope of the claims of the present invention, it is protected by the patent law.

Claims

1. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate, characterized in that: The steps include: Add 2,4-dimethyl-3-pentanol to the solvent, stir evenly, cool to (-30℃) - (-10℃), add the modified catalyst while stirring, keep warm and stir for 0.5-1h, then heat to (-10) - (10)℃, add methacryloyl chloride, keep warm and react for 0.3-1h, after the reaction is completed, return to room temperature, add the functionalized inhibitor, continue stirring for 16-22min, quench the reaction solution, separate the liquid, and then distill to obtain high-purity 2,4-dimethylpentyl-3-yl-methacrylate; The modified catalyst is prepared by an addition reaction between n-butyl lithium and 1,1-diphenylethylene; The functionalized polymerization inhibitor is firstly prepared by amidation reaction of p-hydroxybenzoic acid and diethylenetriamine, and then reacting the diamino monomer with 3,5-di-tert-butyl-4-hydroxybenzoyl chloride through nucleophilic substitution reaction.

2. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 1, characterized in that: The molar ratio of the 2,4-dimethyl-3-pentanol, the modified catalyst, methacryloyl chloride and the functionalized inhibitor is 1: (1.0-1.35): (1.0-1.5): (0.001-0.003).

3. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 1, characterized in that: The modified catalyst is prepared by the following steps: Add n-butyl lithium to cyclohexane and stir evenly. Under anhydrous and oxygen-free conditions, add a mixed solution a of 1,1-diphenylethylene and cyclohexane dropwise. The dripping is controlled to be completed within 10 minutes. After the dripping is completed, the temperature is raised to 34-42°C and the reaction is continued with stirring for 52-64 hours to obtain a modified catalyst.

4. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 3, characterized in that: The mass ratio of n-butyl lithium, cyclohexane and mixed solution a is 2-3:40-50:16-20. In the mixed solution a, the mass ratio of 1-diphenylethylene and cyclohexane is 6.2-9.4:20-30.

5. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 1, characterized in that: The functionalized polymerization inhibitor is prepared by the following steps: Step A1, add p-hydroxybenzoic acid and diethylenetriamine to anhydrous DMF, stir evenly, and drop a mixed solution b of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF while stirring. After the dropwise addition, heat to 62-66° C., stir to react for 3-5 hours, and after the reaction is completed, filter, wash and dry to obtain a diamino monomer; Step A2, add the diamino monomer and potassium carbonate into anhydrous DMF, stir evenly, then add 3,5-di-tert-butyl-4-hydroxybenzoyl chloride, raise the temperature to 52-56° C., continue stirring to react for 8-12 hours, and concentrate under reduced pressure to obtain a functionalized polymerization inhibitor.

6. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 5, characterized in that: In the step A1, the mass ratio of p-hydroxybenzoic acid, diethylenetriamine, anhydrous DMF and mixed solution b is 4.2-5.6:3.2-4.0:60-80:32-44, and in the mixed solution b, the mass ratio of N,N-dicyclohexylcarbodiimide, 4-dimethylaminopyridine and anhydrous DMF is 5.8-7.4:4.0-4.4:26-30.

7. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 5, characterized in that: In the step A2, the mass ratio of the diamino monomer, potassium carbonate, anhydrous DMF and 3,5-di-tert-butyl-4-hydroxybenzoyl chloride is 3.6-4.2: 0.06-0.08: 65-75: 4.0-4.

4.

8. A method for preparing high-purity 2,4-dimethylpentyl-3-yl-methacrylate according to claim 1, characterized in that: The distillation reaction is carried out under reduced pressure, and the pressure range is 150Pa-200Pa.

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