Catalytic synthesis method of glycerol monolaurate diacrylate

Abstract

The invention discloses a catalytic synthesis method of glycerol monolaurate diacrylate, which adopts an enzyme catalysis-chemical catalysis step-by-step method and comprises the following steps of: firstly, synthesizing glycerol monolaurate by reacting glycerol and lauric acid under the catalysis of immobilized lipase, and then synthesizing glycerol monolaurate under the protection of nitrogen in the presence of a polymerization inhibitor. And lauric acid monoglyceride and acrylic acid are catalyzed by the solid acid to generate esterification reaction to generate lauric acid monoglyceride diacrylate. According to the method, glycerol and lauric acid are catalyzed by immobilized lipase to synthesize glycerol monolaurate in a green and efficient manner, primary hydroxyl esterification of glycerol is specifically catalyzed to generate 1 (3)-glycerol monolaurate, secondary hydroxyl almost does not react, and generation of diester byproducts is avoided as much as possible; the solid acid realizes GML dihydroxyl high-selectivity esterification under mild conditions, meanwhile, the double-bond activity of acrylic acid is protected, the double-bond retention rate is greater than 93%, and a high-purity monomer is provided for a UV curing material.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of organic synthesis, and relates to a catalytic synthesis method of glycerol monolaurate diacrylate (GMDA, CAS number: 51826-94-1), in particular to a process for efficiently synthesizing glycerol monolaurate diacrylate by a two-step method, which is suitable for the fields of UV curing materials, bio-based polymer monomers and the like. BACKGROUND

[0002] Lauryl Glyceride Diacrylate is a multifunctional acrylate monomer, mainly used as a key component in light-cured materials (such as UV coatings, inks, adhesives, 3D printing resins), utilizing its molecular structure characteristics to improve the performance of the final materials. The main roles of Lauryl Glyceride Diacrylate are as follows: 1. Provide light-curing reactivity: Lauryl Glyceride Diacrylate molecule contains two acrylate groups, under ultraviolet light (UV) or electron beam (EB) irradiation, these groups can quickly undergo free radical polymerization under the action of photoinitiator, forming a cross-linked network structure, making the liquid resin instantly solidified into a solid film or three-dimensional structure. 2. Improve flexibility and impact resistance: The long-chain lauryl acid group in the Lauryl Glyceride Diacrylate molecule is its key feature, which plays a role similar to an "internal plasticizer" in the polymer network, effectively reducing the glass transition temperature of the cured material, increasing the movement ability of the molecular chain segment, thereby significantly improving the flexibility, ductility and impact resistance of the cured film, which is crucial for applications that require bending, impact resistance or application on flexible substrates (such as flexible coatings, plastic coatings, certain adhesives). 3. Reduce viscosity and improve leveling: Compared to some high-functionality or high-viscosity acrylate monomers, Lauryl Glyceride Diacrylate usually has lower viscosity. It can be used as an active diluent, effectively reducing the overall viscosity of the system, improving processing performance (such as spraying, pouring, printing suitability). Low viscosity also helps the coating to flow better on the substrate, forming a smoother, more uniform surface. 4. Enhance hydrophobicity and water resistance: The long-chain lauryl acid group is hydrophobic, when it is introduced into the polymer network, it can improve the hydrophobicity of the cured material. This helps to improve the water resistance, moisture resistance of the material, reduces water penetration, which is beneficial for outdoor applications, packaging materials or situations that require moisture protection. 5. Influence surface properties and adhesion: The presence of long-chain alkyl groups may have some impact on the surface energy of the cured film, helping to improve the adhesion to low-surface-energy substrates (such as certain plastics PP / PE); it may also affect the surface slip or scratch resistance. 6. Reduce shrinkage stress: During the light-curing process, the monomer polymerizes into a network polymer, usually accompanied by volume shrinkage, generating internal stress. The presence of long-chain flexible groups helps to absorb and distribute part of the shrinkage stress, reducing the problem of coating cracking, warping or adhesion loss caused by excessive stress, which is particularly important in 3D printing. In summary, the core role of Lauryl Glyceride Diacrylate is: as a bifunctional acrylate monomer, it participates in the light-curing cross-linking reaction. Utilizing its long-chain lauryl acid group, it provides excellent flexibility, impact resistance and certain hydrophobicity to the final cured material. As an active diluent, it reduces the viscosity of the system, improves processing and leveling performance. Therefore, it is widely used in UV / EB curing coatings, inks, adhesives, photoresists, 3D printing (light-cured) resins and other fields that require a balance of curing speed, flexibility, low shrinkage and good processing performance.The specific performance and strength of action will be affected by other resins, monomers, photoinitiators in the formula and curing conditions.

[0003] The traditional synthesis process of lauric acid monoglyceride diacrylate is as follows:

[0004] Glycerol and lauric acid are used as raw materials, and acid (such as concentrated sulfuric acid) is often used as catalyst to prepare lauric acid monoglyceride (GML) at 100-110℃ by direct esterification method. However, acid catalysis has the following defects: protonic acid (H + ) has no selective activation of all hydroxyl groups, and will simultaneously generate by-products such as lauric acid diglyceride (Di-GML), lauric acid triglyceride (Tri-GML) and glycerol dimer ether, resulting in low selectivity of monoester and yield of only 60-70%; at the same time, the long-chain alkyl of lauric acid has large steric hindrance, and the reaction activity is low, so the conventional catalyst (such as concentrated sulfuric acid) is easy to initiate olefin side reaction. High temperature will also promote glycerol dehydration to generate glycidol (epoxy by-product).

[0005] The traditional synthesis of glyceride acrylate often uses acid (such as concentrated sulfuric acid, p-toluenesulfonic acid) as catalyst, and lauric acid monoglyceride and acrylic acid are esterified by direct esterification method to generate lauric acid monoglyceride diacrylate, but there are problems such as many by-products (such as excessive generation of diacrylate), polymerization of acrylic acid at high temperature, and the catalyst cannot be recycled (see Table 1).

[0006] In the traditional process, the addition of copper oxide and other auxiliary materials will cause metal ion pollution of the product.

[0007] Therefore, it is necessary to develop a synthesis route with high selectivity, low energy consumption and no metal residue to meet the demand of biocompatible materials. SUMMARY

[0008] The purpose of the present application is to provide a catalytic synthesis method of lauric acid monoglyceride diacrylate, which solves the selectivity problem by step-by-step catalysis + green catalyst, reduces energy consumption and pollution, and meets the trend of green chemistry.

[0009] The purpose of the present application is achieved by the following technical scheme:

[0010] A catalytic synthesis method of lauric acid monoglyceride diacrylate, which adopts enzyme catalysis-chemical catalysis step-by-step method, first synthesizes lauric acid monoglyceride (GML) by immobilized lipase catalysis of glycerol and lauric acid, and then generates lauric acid monoglyceride diacrylate by esterification reaction of lauric acid monoglyceride and acrylic acid under the protection of nitrogen and in the presence of polymerization inhibitor.

[0011] Specifically, the catalytic synthesis method of lauric acid monoglyceride diacrylate comprises the following steps:

[0012] Step (1), synthesis of lauric acid monoglyceride: taking glycerol and lauric acid as raw materials, immobilized lipase as catalyst, and cyclohexane as reaction solvent, the reaction was carried out at a temperature of 60-70℃ and a pressure of ≤10 kPa for 4-6 h; after the reaction was completed, water washing, alkali washing and water washing were carried out in sequence, and the obtained organic phase was subjected to vacuum distillation to remove the reaction solvent, thereby obtaining lauric acid monoglyceride;

[0013] Step (2), under the conditions of nitrogen protection and the presence of a polymerization inhibitor, esterification reaction of lauric acid monoglyceride and acrylic acid was carried out in the presence of solid acid as catalyst and cyclohexane as reaction solvent, thereby generating lauric acid monoglyceride diacrylate; after the reaction was completed, the reaction mixture was subjected to purification treatment, thereby obtaining lauric acid monoglyceride diacrylate product.

[0014] In step (1), the molar ratio of glycerol to lauric acid is 1:0.8-1:1.2, preferably 1:1.05-1:1.1.

[0015] The immobilized lipase is Novozym 435.

[0016] The amount of immobilized lipase used is 3-7%wt of the total mass of glycerol and lauric acid.

[0017] Specifically, the amount of immobilized lipase used can be 5%wt of the total mass of glycerol and lauric acid.

[0018] The mass ratio of glycerol to cyclohexane is 1:6-1:8.

[0019] Specifically, the reaction temperature can be 65±2℃, and the reaction pressure can be 8.0±0.5 kPa.

[0020] Specifically: after the reaction was completed, the material was cooled to below 60℃, and water washing, alkali washing and water washing were carried out in sequence; water was added according to the mass ratio of lauric acid to water of 1:0.8-1:0.95, stirred and then allowed to stand, and the lower aqueous phase was separated; 15-18% NaOH solution was added to the water-washed organic phase according to the mass ratio of lauric acid to 15-18% NaOH solution of 1:0.8-1:0.95, stirred and then allowed to stand, and the lower aqueous phase was separated; finally, water was added to the alkali-washed organic phase according to the mass ratio of lauric acid to water of 1:0.8-1:0.95, stirred and then allowed to stand, and the lower aqueous phase was separated, and the organic phase was retained.

[0021] The temperature of vacuum distillation is 85-100℃, and the pressure of vacuum distillation is 0.03-0.10 kPa.

[0022] In step (2), the polymerization inhibitor is 4-methoxyphenol (MEHQ). The amount of the polymerization inhibitor is 200-500 ppm of the total mass of glyceryl monolaurate and acrylic acid.

[0023] The molar ratio of glyceryl monolaurate to acrylic acid is 1:2.2-1:2.5.

[0024] The mass of cyclohexane is 2 times the total mass of GML and acrylic acid.

[0025] The solid acid is a sulfonic group functionalized porous carbon material, specifically sulfonated carbon-based solid acid (denoted as SO3H@C). The BET specific surface area of the solid acid is ≥500 m² / g, and the loading of sulfonic groups is >1.5 mmol / g. The solid acid catalyst achieves high conversion and monoester selectivity at a lower temperature. When the BET specific surface area of the solid acid is less than 500 m² / g, the yield of glyceryl monolaurate diacrylate decreases significantly. The inventors tried to use a solid acid with a BET specific surface area of 480 m² / g, and the yield of glyceryl monolaurate diacrylate decreased to 85%.

[0026] The amount of the sulfonic group functionalized porous carbon material used as the solid acid is 5-7 wt% of the total mass of glyceryl monolaurate and acrylic acid.

[0027] The sulfonated carbon-based solid acid is prepared by the following method: sucrose and deionized water are mixed in a ratio of 1:1 g / mL, sucrose is dissolved in deionized water, and carbon microspheres are obtained by hydrothermal carbonization at 180°C; the carbon microspheres are mixed with concentrated sulfuric acid in a ratio of 1:10 g / mL, and the carbon microspheres are sulfonated and modified under nitrogen protection at 150°C; the sulfonated and modified product is washed with deionized water, the pH is adjusted to neutral with lye, and finally washed with deionized water, and vacuum dried to obtain the sulfonated carbon-based solid acid.

[0028] The mass fraction of the concentrated sulfuric acid is 98%.

[0029] The lye is a 20% mass fraction sodium hydroxide aqueous solution or a 15% mass fraction sodium carbonate aqueous solution.

[0030] Specifically, the sulfonated and modified product is washed with deionized water twice, the amount of deionized water used each time is 10% wt of the total mass of carbon microspheres and concentrated sulfuric acid, the pH is adjusted to neutral with lye, and the product is washed with deionized water twice, the amount of deionized water used each time is 5% wt of the total mass of carbon microspheres and concentrated sulfuric acid.

[0031] The temperature of the vacuum drying is 120°C.

[0032] The esterification reaction temperature is 90-110℃, the esterification reaction time is 3-5 h, and the esterification rate is ≥92%.

[0033] The purification treatment includes: the reaction mixture is sequentially subjected to water washing, alkali washing and water washing, the organic phase obtained after washing is subjected to vacuum distillation to remove unreacted acrylic acid, and then subjected to normal phase silica gel column chromatography to obtain lauric acid monoglyceride diacrylate product (purity > 98%).

[0034] The alkali washing adopts 15-18% NaOH solution.

[0035] Specifically: the reaction mixture is sequentially subjected to water washing, alkali washing and water washing: water is added according to the use amount ratio of lauric acid monoglyceride and water of 0.1 mol:200 g, stirred and then allowed to stand, the lower water phase is separated, 15-18% NaOH solution is added to the organic phase subjected to water washing according to the use amount ratio of lauric acid monoglyceride and 15-18% NaOH solution of 0.1 mol:200 g, stirred and then allowed to stand, the lower water phase is separated, and finally water is added to the organic phase subjected to alkali washing according to the use amount ratio of lauric acid monoglyceride and water of 0.1 mol:200 g, stirred and then allowed to stand, the lower water phase is separated, and the organic phase is retained.

[0036] The temperature of the vacuum distillation is 85-100℃ (to prevent GMDA thermal polymerization), and the pressure of the vacuum distillation is 0.10-0.03 kPa.

[0037] The eluent of the normal phase silica gel column chromatography is petroleum ether / ethyl acetate=3:1 v / v.

[0038] Stepwise reaction mechanism:

[0039] 1: Esterification of GML secondary hydroxyl group (preferential reaction). The secondary hydroxyl group (-CH(OH)-) on the glycerol skeleton has small steric hindrance, and reacts with acrylic acid first:

[0040] Activation of the secondary hydroxyl group of GML:

[0041] R-COOH (acrylic acid) + SO3H (solid acid) → R-C + (OH)OSO3 - ;

[0042] Electrophilic attack:

[0043] R-C + (OH)OSO3 - + HO-CH(CH2OR') → R-COO-CH(CH2OR') + H2O + SO3H

[0044] Wherein, R= -CH=CH2, R'= lauroyl group.

[0045] 2: GML primary hydroxyl esterification. The remaining primary hydroxyl (-CH2OH) continues to react:

[0046] R-COOH + SO3H → R-C + (OH)OSO3 -

[0047] R-C + (OH)OSO3 - + HO-CH2- → R-COO-CH2- + H2O + SO3H

[0048] The lauric acid monoglyceride diacrylate obtained by the method described in the application has the application of preparing UV curing paint, medical polymer material, biological plastic plasticizer, food emulsifier.

[0049] Photocurable material: lauric acid monoglyceride diacrylate as a flexible monomer enhances coating adhesion; Medical polymer material: functional nanomicelles are constructed by using the antibacterial property of lauric acid chain as a drug carrier; Biological plasticizer: improve the brittleness of polylactic acid (PLA) material.

[0050] The beneficial effects of the application are:

[0051] I. Enzymatic catalysis advantage: the application adopts immobilized lipase to catalyze glycerol and lauric acid to green and efficiently synthesize lauric acid monoglyceride. Enzymatic catalysis has specificity and high selectivity. The hydrophobic tunnel of the activity pocket of the lipase selectively combines the long chain of lauric acid, and directionally attacks the primary hydroxyl group of glycerol (small steric hindrance) to specifically catalyze the esterification of the primary hydroxyl group (-CH2OH) of glycerol to generate 1(3)-lauric acid monoglyceride (sn-1 or sn-3 isomer mixture). The secondary hydroxyl group (-CH(OH)-) hardly reacts, and the generation of diester by-products is avoided as much as possible. At the same time, glycerol and lauric acid are synthesized into lauric acid monoglyceride under vacuum conditions. Vacuum dehydration drives the balance to move to the right. The conversion rate of glycerol is ≥95%, and the selectivity of lauric acid monoglyceride is >98%.

[0052] II. The solid acid catalyst (such as SO3H@C) realizes the high-selectivity esterification of GML double hydroxyl groups under mild conditions, and protects the activity of the acrylic double bond at the same time, thereby providing high-purity monomers for UV curing materials.

[0053] Key to inhibit side reactions:

[0054] 1. Avoiding self-polymerization of acrylic acid:

[0055] Inhibitor MEHQ captures free radicals:

[0056] CH2=CH• (free radical) + MEHQ → inert product

[0057] Low temperature control (<110℃) reduces polymerization rate;

[0058] 2. Avoid excessive esterification:

[0059] Precise control of the molar ratio of acrylic acid and GML, excess acrylic acid drives the balance but can be recovered;

[0060] 3. Avoid lauric acid ester hydrolysis:

[0061] Solid acid has no strong Bronsted acidity, avoiding ester bond rupture.

[0062] Table 1. Comparison of solid acid catalytic method and traditional process of the present application

[0063]

[0064] III. Enzyme catalyst can be reused more than 5 times, activity remains >90%; solid acid replaces corrosive acid, solid acid catalyst activates carboxyl group through surface sulfonic acid group, avoiding metal ion pollution.

[0065] IV. High selectivity: avoid triglyceride byproduct, GMDA purity >98% (HPLC verification); product performance: double bond retention rate >93%, suitable for photocuring (DSC detects polymerization enthalpy ≥120 J / g). DETAILED DESCRIPTION

[0066] Example 1

[0067] Preparation of sulfonated carbon-based solid acid (SO3H@C), including the following steps:

[0068] Step (1), carbon source pretreatment: dissolve 100 g of sucrose in 100 mL of deionized water, carbonize at 180℃ for 12 h, and obtain carbon microspheres;

[0069] Step (2), sulfonation modification: mix carbon microspheres with concentrated sulfuric acid (98%) at 1:10 (w / v, g / mL), reflux at 150℃ for 6 h under nitrogen protection;

[0070] Step (3), post-treatment: first wash the sulfonation modification product with deionized water twice, the amount of deionized water used each time is 10%wt of the total mass of carbon microspheres and concentrated sulfuric acid, then adjust the pH to neutral with 20%wt sodium hydroxide aqueous solution or 15%wt sodium carbonate aqueous solution, wash with deionized water twice, the amount of deionized water used each time is 5%wt of the total mass of carbon microspheres and concentrated sulfuric acid, vacuum dry at 120℃, and obtain sulfonated carbon-based solid acid (SO3H@C).

[0071] BET specific surface area of SO3H@C: 523 m 2 / g (determined by Micromeritics ASAP 2020), sulfonic group density: 1.8 mmol / g (elemental analysis S content -> -SO3H calculation).

[0072] In the FT-IR spectrum of SO3H@C, 1040 cm -1 (S=O stretching vibration), 3420 cm -1 (-OH broad peak) can be observed, proving the presence of -SO3H in SO3H@C.

[0073] In the SEM image of SO3H@C, mesoporous structure of 3-5 nm level can be observed.

[0074] Example 2

[0075] Preparation of glyceryl laurate (GML): according to the molar ratio of glycerol and lauric acid about 1:1.05, the amount of immobilized lipase Novozym 435 about 5.0%wt of the total mass of glycerol and lauric acid, glycerol (92.1 g), lauric acid (211.7 g), Novozym 435 (15.2 g) and cyclohexane (600 g) were put into a 50 L vacuum stirring reaction kettle (Pfaudler GmbH), stirring reaction at temperature 65±2℃, vacuum 8.0±0.5 kPa, rotation speed 250 rpm, HPLC monitoring reaction progress, when the reaction time was 5.0 h, the conversion rate of glycerol was 96.5%, stop heating, start cooling system, cool the material in the reaction kettle to below 60℃; add 200 g water to the reaction kettle, stir for 15 min, stand for 30 min, separate the lower aqueous phase; then add 200 g of 15% NaOH solution to the reaction kettle, stir for 30 min, stand for 30 min, separate the lower aqueous phase; then add 200 g of water to the reaction kettle, stir for 15 min, stand for 30 min, separate the lower aqueous phase; the organic phase obtained after washing was distilled under reduced pressure at temperature 85-100℃, pressure 0.10-0.03 kPa for 40 min to remove cyclohexane, and glyceryl laurate (291.3 g, purity 98.7%, water content (determined by Karl Fischer method) 0.04%) was obtained.

[0076] There is ester group peak (δ=4.1 ppm, -CH2OCOR) in the 1H-NMR of glyceryl laurate, no secondary hydroxyl esterification (δ=3.6 ppm, -CH(OH)- not shifted).

[0077] Example 3

[0078] According to the molar ratio of acrylic acid and GML is 2.2:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol (MEHQ, polymerization inhibitor) is 250 ppm of the total amount of GML and acrylic acid, the amount of sulfonated carbon-based solid acid (SO3H@C, Example 2) is 7 wt% of the total mass of GML and acrylic acid, acrylic acid, GML (0.1 mol), cyclohexane, 4-methoxyphenol, sulfonated carbon-based solid acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid undergo esterification reaction at a temperature of 95℃, and the reaction is carried out for 4 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, the sulfonated carbon-based solid acid is separated by filtration, 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated, then 200g of 18% mass fraction NaOH solution is added to the reaction kettle, stirred for 30min, and static for 30min, the lower aqueous phase is separated, then 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, and the crude GMDA is obtained; the crude GMDA is subjected to normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3:1, v / v) purification, and the GMDA product (colorless oil, yield 93%, double bond retention rate 97%, acrylic acid dimer content 0.8%, no dehydrated glycerol ester detected) is obtained.

[0079] The following characteristic peaks can be observed in the 1H-NMR of GMDA (CDCl3, δ / ppm): acryloyl double bond: δ=5.8-6.4 (m, 3H, -CH=CH2), glycerol skeleton: δ=4.3 (t, 2H, -CH2-OCOR), lauric acid chain: δ=0.88 (t, 3H, -CH3), no hydroxyl peak (δ=2.5-3.5 disappeared); the following characteristic peaks can be observed in the 13C-NMR of GMDA: ester carbonyl: δ=166.5 ppm, acrylic acid double bond: δ=130.5 ppm. The following characteristic peaks can be observed in the FT-IR of GMDA: ester carbonyl (C=O): 1735 cm -1 , acrylic acid double bond (C=C): 1630 cm -1 , no free -OH wide peak (3300 cm -1 ).

[0080] Comparative Example 1

[0081] According to the molar ratio of acrylic acid and GML is 2.5:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, the amount of concentrated sulfuric acid (98%) is 5 wt% of the total mass of GML and acrylic acid, acrylic acid, GML (0.1 mol), cyclohexane, 4-methoxyphenol, concentrated sulfuric acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid undergo esterification reaction at a temperature of 110℃, the reaction is carried out for 4 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, 200g of water is added to the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated, then 200g of 18% NaOH solution is added to the reaction kettle, stirred for 30min, static for 30min, the lower aqueous phase is separated, then 200g of water is added to the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, to obtain GMDA crude product; the GMDA crude product is purified by normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate=3:1, v / v) to obtain GMDA product (colorless oil, yield 68%, double bond retention rate 72%, acrylic acid polymer content 12.5%, glycidyl laurate content 4.2%).

[0082] Comparative Example 2

[0083] According to the molar ratio of acrylic acid and GML is 2.3:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, the amount of p-toluenesulfonic acid is 5 wt% of the total mass of GML and acrylic acid, acrylic acid, GML (0.1 mol), cyclohexane, 4-methoxyphenol, p-toluenesulfonic acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid undergo esterification reaction at a temperature of 100℃, the reaction is carried out for 4 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, 200g of water is added to the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated, then 200g of 18% NaOH solution is added to the reaction kettle, stirred for 30min, static for 30min, the lower aqueous phase is separated, then 200g of water is added to the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, to obtain GMDA crude product; the GMDA crude product is purified by normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate=3:1, v / v) to obtain GMDA product (colorless oil, yield 75%, double bond retention rate 80%).

[0084] Comparative Example 3

[0085] According to the molar ratio of acrylic acid and GML is 3.0:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, acrylic acid, GML (0.1 mol), cyclohexane, 4-methoxyphenol are weighed and put into the reaction kettle, under the protection of nitrogen, lauric acid monoglyceride and acrylic acid undergo esterification reaction at a temperature of 120°C, the reaction is carried out for 6 hours, and the yield of GMDA is <30%. After the reaction is completed, the reaction liquid is cooled to 60°C, 200 g of water is added to the reaction kettle, stirred for 15 min, and static for 30 min, the lower aqueous phase is separated, 200 g of 18% NaOH solution is added to the reaction kettle, stirred for 30 min, and static for 30 min, the lower aqueous phase is separated, then 200 g of water is added to the reaction kettle, stirred for 15 min, and static for 30 min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100°C, pressure 0.10-0.03 kPa) to remove the solvent, and GMDA crude product is obtained; the GMDA crude product is subjected to normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3:1, v / v) purification, and GMDA product (colorless oil, yield <30%) is obtained.

[0086] Table 2. Preparation of GMDA by different catalytic processes (GML is fixed at 0.1 mol)

[0087]

[0088] Example 4

[0089] According to the molar ratio of acrylic acid and GML is 2.2:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, the amount of sulfonated carbon-based solid acid (SO3H@C, Example 2) is 7 wt% of the total mass of GML and acrylic acid, acrylic acid (0.22 mol), GML (0.1 mol), cyclohexane, 4-methoxyphenol, sulfonated carbon-based solid acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid occur esterification reaction at a temperature of 90℃, the reaction is carried out for 5 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, the sulfonated carbon-based solid acid is separated by filtration, 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated, 200g of 18% NaOH solution is added to the reaction kettle, stirred for 30min, and static for 30min, the lower aqueous phase is separated, then 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, and GMDA crude product is obtained; the GMDA crude product is subjected to normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 3:1, v / v) purification, and GMDA product (colorless oil, yield 89%, double bond retention rate 95%) is obtained.

[0090] Example 5

[0091] According to the molar ratio of acrylic acid and GML is 2.5:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, the amount of sulfonated carbon-based solid acid (SO3H@C, Example 2) is 7 wt% of the total mass of GML and acrylic acid, acrylic acid (0.25 mol), GML (0.1 mol), cyclohexane, 4-methoxyphenol, sulfonated carbon-based solid acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid occur esterification reaction at a temperature of 110℃, the reaction is carried out for 3.5 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, the sulfonated carbon-based solid acid is separated by filtration, 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated, 200g of 18% NaOH solution is added to the reaction kettle, stirred for 30min, and static for 30min, the lower aqueous phase is separated, then 200g of water is added to the reaction kettle, stirred for 15min, and static for 30min, the lower aqueous phase is separated; the organic phase obtained after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, and GMDA crude product is obtained; the GMDA crude product is subjected to normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate=3:1, v / v) purification, and GMDA product (colorless oil, yield 91%, double bond retention rate 93%) is obtained.

[0092] Example 6

[0093] According to the molar ratio of acrylic acid and GML is 2.4:1, the mass of cyclohexane is 2 times of the total mass of GML and acrylic acid, the amount of 4-methoxyphenol is 250 ppm of the total amount of GML and acrylic acid, the amount of sulfonated carbon-based solid acid (SO3H@C, Example 2) is 7wt% of the total mass of GML and acrylic acid, acrylic acid (0.24 mol), GML (0.1 mol), cyclohexane, 4-methoxyphenol, sulfonated carbon-based solid acid are weighed and put into the reaction kettle, under the protection of nitrogen, GML and acrylic acid occur esterification reaction at the temperature of 100℃, the reaction is carried out for 4 hours; after the reaction is completed, the reaction liquid is cooled to 60℃, the sulfonated carbon-based solid acid is separated by filtration, 200g water is added into the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated, then 200g 18% NaOH solution is added into the reaction kettle, stirred for 30min, static for 30min, the lower aqueous phase is separated, then 200g water is added into the reaction kettle, stirred for 15min, static for 30min, the lower aqueous phase is separated; the obtained organic phase after washing is subjected to vacuum distillation (temperature 85-100℃, pressure 0.10-0.03 kPa) to remove the solvent, to obtain GMDA crude product; the GMDA crude product is subjected to normal phase silica gel column chromatography (eluent: petroleum ether / ethyl acetate=3:1, v / v) purification, to obtain GMDA product (colorless oil, yield 92%, double bond retention rate 96%).

Claims

1. A process for the catalytic synthesis of lauric acid monoglyceride diacrylate, characterized by: The method comprises the following steps:

2. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1, characterized in that: The method comprises the following steps: Step (1), synthesis of monoglyceride laurate: glycerol and lauric acid are used as raw materials, immobilized lipase is used as catalyst, and cyclohexane is used as reaction solvent; the reaction is carried out at a temperature of 60-70 DEG C and a pressure of less than or equal to 10 kPa for 4-6 hours; after the reaction is completed, water washing, alkali washing and water washing are sequentially performed; the obtained organic phase is subjected to vacuum distillation to remove the reaction solvent, thereby obtaining monoglyceride laurate; Step (2), under the conditions of nitrogen protection and presence of a polymerization inhibitor, a solid acid is used as catalyst and cyclohexane is used as reaction solvent; the esterification reaction of monoglyceride laurate and acrylic acid is carried out at a temperature of 90-110 DEG C, thereby generating monoglyceride laurate diacrylate; after the reaction is completed, the reaction mixture is subjected to purification treatment, thereby obtaining monoglyceride laurate diacrylate product.

3. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1 or 2, characterized in that: The molar ratio of glycerol to lauric acid is 1:0.8-1:1.2, preferably 1:1.05-1:1.1; the molar ratio of monoglyceride laurate to acrylic acid is 1:2.2-1:2.

5.

4. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1 or 2, characterized in that: The immobilized lipase is Novozym 435; the amount of the immobilized lipase is 3-7%wt of the total mass of glycerol and lauric acid.

5. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1 or 2, characterized in that: The amount of the immobilized lipase is 3-7%wt of the total mass of glycerol and lauric acid.

6. The process for catalytic synthesis of monoglyceride dilaurate diacrylate as claimed in claim 2, wherein: In step (1), the temperature of the vacuum distillation is 80-86 DEG C, and the pressure of the vacuum distillation is 0.10 kPa.

7. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1 or 2, characterized in that: The polymerization inhibitor is 4-methoxyphenol; the amount of the polymerization inhibitor is 200-500 ppm of the total mass of monoglyceride laurate and acrylic acid.

8. A process for the catalytic synthesis of monoglyceride dilaurate according to claim 1 or 2, characterized in that: The solid acid is a sulfonic group functionalized porous carbon material; the BET surface area of the solid acid is greater than or equal to 500 m² / g, and the loading amount of the sulfonic group is greater than 1.5 mmol / g; the amount of the solid acid is 5-7%wt of the total mass of monoglyceride laurate and acrylic acid.

9. The process for catalytic synthesis of monoglyceride dilaurate diacrylate as claimed in claim 8, wherein: The solid acid is a sulfonated carbon-based solid acid; the sulfonated carbon-based solid acid is prepared by the following method: sucrose and deionized water are mixed according to a mass ratio of 1:1 g / mL, and the sucrose is dissolved in the deionized water; carbon microspheres are obtained by hydrothermal carbonization at 180 DEG C; the carbon microspheres are mixed with concentrated sulfuric acid according to a mass ratio of 1:10 g / mL, and the carbon microspheres are subjected to sulfonation modification under nitrogen protection at 150 DEG C; the sulfonation modification product is washed with deionized water, the pH is adjusted to neutral with lye, and then the sulfonation modification product is washed with deionized water again; the sulfonated carbon-based solid acid is obtained by vacuum drying.

10. The process for catalytic synthesis of monoglyceride dilaurate diacrylate as claimed in claim 2, wherein: The purification treatment comprises: sequentially performing water washing, alkali washing and water washing on the reaction mixture, removing unreacted acrylic acid from the organic phase obtained after washing through reduced pressure distillation, and then performing normal phase silica gel column chromatography to obtain the lauric acid monoglyceride diacrylate product; wherein the alkali washing uses 15-18% NaOH solution; the temperature of the reduced pressure distillation is 85-100 DEG C, and the pressure of the reduced pressure distillation is 0.10-0.03 kPa.

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