Process for the production of allyl diglycol dicarbonate

Abstract

This invention relates to the field of chemical synthesis, and more particularly to a process for producing allyl diethylene glycol dicarbonate, comprising the following steps: using allyl alcohol and dimethyl carbonate as raw materials, a transesterification reaction is carried out under the action of a core-shell catalyst to produce dipropylene carbonate; after solid-liquid separation and vacuum distillation to recover methanol and dimethyl carbonate, a second transesterification reaction is carried out with diethylene glycol under the same catalyst to produce allyl diethylene glycol dicarbonate; finally, high-purity product is obtained by multi-stage vacuum distillation purification. The core-shell catalyst uses MCM-41 molecular sieve as a support, with an amino-modified and zirconium-ion-coordinated core, encapsulated by an interface layer and a phenyl-modified silica shell, exhibiting high activity, high selectivity, and excellent structural stability. This process is mild, the catalyst is recyclable, and the product yield is high with excellent purity, making it suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of chemical synthesis, and more particularly to a process for producing allyl diethylene glycol dicarbonate. Background Technology

[0002] Allyl diethylene glycol dicarbonate is an important organic carbonate compound widely used in polymer materials, optical resins, pharmaceutical intermediates, and functional solvents. Its molecular structure contains both allyl and carbonate groups, giving it excellent reactivity and controllable physicochemical properties. It exhibits particularly outstanding performance in UV-curable resins and high-refractive-index optical materials, thus its synthesis process has attracted considerable attention.

[0003] Currently, the commonly used industrial methods for synthesizing allyl diethylene glycol dicarbonate are mostly based on transesterification reactions. This involves first synthesizing dipropylene carbonate from allyl alcohol and dimethyl carbonate, followed by a second-step transesterification reaction with diethylene glycol. The key challenge of this process lies in the selection of catalysts and the control of the reaction process. Traditional processes often use homogeneous basic catalysts, such as sodium methoxide and potassium hydroxide. While these catalysts possess certain catalytic activity, they easily trigger side reactions such as allyl alcohol dehydration, double bond addition, and ester hydrolysis, leading to low product purity and complex post-processing. Furthermore, homogeneous catalysts are difficult to recover and reuse, increasing production costs and causing environmental pollution.

[0004] Furthermore, existing processes also have certain limitations in separation and purification. Due to the presence of multiple components with similar boiling points in the reaction system, such as methanol, dimethyl carbonate, allyl alcohol, and dipropylene carbonate, traditional distillation methods are difficult to achieve efficient separation. They often require multiple vacuum distillations or the introduction of auxiliary methods such as extraction and crystallization, which is not only complex to operate but also prone to thermal decomposition or oxidation of the product, affecting the quality and yield of the final product. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a production process for allyl diethylene glycol dicarbonate. By improving the catalyst, the problems of excessive by-products and low product purity during the reaction process are solved, resulting in milder process conditions, higher product yield, and better purity. This is achieved through the following methods.

[0006] This invention discloses a process for producing allyl diethylene glycol dicarbonate, specifically comprising the following steps:

[0007] Step 1: Allyl alcohol and dimethyl carbonate undergo a first transesterification reaction in the presence of a core-shell catalyst to produce a dipropylene carbonate mixture.

[0008] Step 2: Perform solid-liquid separation on the mixture, recover the catalyst and collect the liquid;

[0009] Step 3: Perform two vacuum distillations on the liquid to separate methanol and dimethyl carbonate in sequence, thereby obtaining dipropylene carbonate;

[0010] Step 4: The dipropylene carbonate and diethylene glycol undergo a second transesterification reaction in the presence of the core-shell catalyst to generate a mixture containing allyl diethylene glycol dicarbonate.

[0011] Step 5: The mixture is subjected to vacuum distillation to separate allyl alcohol and dipropylene carbonate in sequence, yielding crude allyl diethylene glycol dicarbonate.

[0012] Step 6: The crude product is subjected to high-vacuum distillation to obtain purified allyl diethylene glycol dicarbonate;

[0013] The core-shell catalyst comprises a three-layer structure from the inside out:

[0014] The core is modified with aminopropyltriethoxysilane and loaded with Zr. 4+ MCM-41 molecular sieve;

[0015] An interface modification layer is connected to the core via an epoxy-containing silane coupling agent;

[0016] The outer shell is a mesoporous SiO2 structure containing phenyl groups.

[0017] Preferably, the preparation method of the core-shell catalyst includes the following steps:

[0018] S1: High-temperature calcination treatment of MCM-41 molecular sieve;

[0019] S2: Modification of calcined MCM-41 using aminopropyltriethoxysilane;

[0020] S3: Treat the modified MCM-41 with ZrCl4 ethanol solution to introduce Zr 4+ The kernel product is obtained;

[0021] S4: React the core product with an epoxy-containing silane coupling agent to form an interface modification layer;

[0022] S5: Under acidic conditions, tetraethyl orthosilicate and phenyltriethoxysilane are co-condensed on a core containing an interface-modified layer to form a shell, and the core-shell catalyst is obtained after calcination.

[0023] Preferably, the molar ratio of allyl alcohol to dimethyl carbonate in step 1 is 1:2.5 to 3.5;

[0024] The amount of the core-shell catalyst added is 3% to 5% of the mass of allyl alcohol;

[0025] In step 1, the reaction temperature is 80–90°C and the reaction time is 6–8 hours.

[0026] Preferably, the reaction in step 1 is carried out under stirring conditions, with a stirring rate of 80 r / min.

[0027] Preferably, in step 4, the molar ratio of diethylene glycol to dipropylene carbonate is 1:2.2 to 2.4, the amount of the core-shell catalyst added is 3% to 5% of the mass of diethylene glycol, the reaction temperature is 80 to 105°C, and the reaction time is 4 to 5 hours.

[0028] Preferably, in step 3, the pressure of the first distillation is 0.1 MPa and the temperature is 63-68°C, and the pressure of the second distillation is 0.05 MPa and the temperature is 88-92°C.

[0029] Preferably, the pressure of the first distillation in step 5 is 0.1 MPa and the temperature is 93-100℃;

[0030] The second distillation was carried out at a pressure of 0.015 MPa, a temperature of 130–135 °C, and a distillation time of 2–3 hours.

[0031] Preferably, in step 6, the pressure of the high-vacuum distillation is 20-80 Pa, the temperature is 130-140 °C, and the distillation time is 1 hour.

[0032] Preferably, the conditions for high-temperature calcination in step S1 are: heating to 500°C at a rate of 5°C / min and holding at that temperature for 4 hours;

[0033] In step S5, the pH value of the acidic conditions is 4-5, the calcination temperature is 150℃, and the calcination time is 2 hours.

[0034] Preferably, the mass ratio of MCM-41 molecular sieve, anhydrous toluene, and aminopropyltriethoxysilane in step S2 is 1:8-9:0.12-0.15;

[0035] The epoxy-containing silane coupling agent mentioned in step S4 is γ-glycidoxypropyltrimethoxysilane.

[0036] After adopting the above technical solution, the beneficial effects of the present invention are:

[0037] 1. This invention achieves highly efficient catalysis of transesterification reaction by employing a catalyst with a specific core-shell structure. The synergistic effect of amino groups and zirconium ions in the core significantly improves the reaction rate and conversion rate, resulting in a significant increase in product yield.

[0038] 2. The phenyl groups in the catalyst shell form a molecular barrier, effectively preventing large molecular by-reactants from entering the core, significantly reducing the occurrence of side reactions such as double bond addition and dehydration, thereby improving the purity and reaction selectivity of the product.

[0039] 3. The introduction of the interface modification layer enhances the bonding force between the core and the shell, reduces the risk of shell detachment during the reaction, and thus significantly improves the mechanical stability and recycling rate of the catalyst, reducing catalyst loss and operating costs in industrial production.

[0040] 4. By optimizing the distillation process parameters, efficient separation and recovery of each component in the reaction system were achieved, avoiding thermal damage to the product caused by high temperature, while improving the utilization rate of raw materials, which meets the requirements of green chemical industry.

[0041] 5. The overall process conditions of this invention are mild and easy to operate, making it suitable for large-scale production and possessing good industrial application prospects and economic benefits. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 Scanning electron microscope image of the core-shell catalyst initially prepared;

[0044] Figure 2 This is a scanning electron microscope image of the core-shell catalyst after it has been recycled three times and sieved. Detailed Implementation

[0045] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain the present invention and are not configured to limit the present invention. For those skilled in the art, the present invention can be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the invention.

[0046] An embodiment of the present invention provides a process for producing allyl diethylene glycol dicarbonate, specifically including the following steps:

[0047] Step 1

[0048] Allyl alcohol and dimethyl carbonate are fed into a reactor preheated to 50°C. A core-shell catalyst is added to the reactor. The reaction temperature in the reactor is controlled at 80–90°C. The stirring rate in the reactor is controlled at 80 r / min. The reactor is refluxed for 6–8 hours. After the reaction is completed, a dipropylene carbonate mixture is obtained.

[0049] The molar ratio of added allyl alcohol to dimethyl carbonate is 1:2.5 to 3.5, and the amount of core-shell catalyst added is 3% to 5% of the mass of allyl alcohol.

[0050] In the above reaction process, the dimethyl carbonate molecule in the reactants contains two methoxycarbonyl groups, while the hydroxyl group of allyl alcohol is a nucleophilic site. The two undergo a transesterification reaction to produce dipropylene carbonate and methanol. The reaction equation is as follows:

[0051]

[0052] The target intermediate, dipropylene carbonate, is generated through transesterification, laying the foundation for the subsequent preparation of allyl diethylene glycol dicarbonate. Furthermore, the molar ratio of reactants, reaction temperature, stirring rate, and reaction time are precisely controlled during the above reaction process to ensure that the reaction proceeds fully.

[0053] Adding an excess of dimethyl carbonate can improve the conversion rate of allyl alcohol, ensure that allyl alcohol reacts fully to form dipropylene carbonate, reduce unreacted allyl alcohol residue, and reduce the difficulty of subsequent separation and purification.

[0054] The above process employs a reaction temperature of 80–90°C, which effectively activates the core-shell catalyst, accelerates the transesterification reaction rate, and avoids excessive temperature leading to reactant volatilization, decomposition, or excessive side reactions. A stirring rate of 80 r / min is used during the reaction to ensure thorough mixing of allyl alcohol, dimethyl carbonate, and the catalyst in the reactor, increasing the contact probability between reactant molecules and the catalyst's active sites, promoting uniform reaction, and preventing excessively high or low local reactant concentrations from affecting reaction efficiency and product formation. The overall reaction time is controlled within 6–8 hours to ensure the transesterification reaction proceeds fully, maximizing the conversion of reactants into products.

[0055] The core-shell catalyst used in the above reaction process is a multi-active-site catalyst coated with a mesoporous SiO2 shell. The specific preparation steps of this catalyst are as follows:

[0056] S1: Place the MCM-41 molecular sieve in a muffle furnace, heat it to 500°C at a rate of 5°C / min, hold it at that temperature for 4 hours, and then cool it to room temperature with the furnace for later use.

[0057] Among them, MCM-41 molecular sieve is a silicon-based material with a hexagonal ordered mesoporous structure. Due to its structural designability and chemical modifiability, this invention selects MCM-41 molecular sieve as a catalyst support.

[0058] During storage, the mesoporous channels of MCM-41 molecular sieve adsorb water molecules from the air. When calcined at 500℃, the heat energy can break the van der Waals forces between the water molecules and the channel walls, allowing the water molecules to escape in gaseous form.

[0059] In addition, calcination at 500℃ can break some of the siloxane bonds on the surface of MCM-41 molecular sieve, generating more active silanol groups, which provide reaction sites for subsequent reactions.

[0060] S2: Disperse the calcined MCM-41 molecular sieve in anhydrous toluene, then add aminopropyltriethoxysilane, heat to 80℃ and react for 6 hours. After the reaction is completed, filter to collect the solid and wash it 3 times with anhydrous ethanol. Then dry it under vacuum at 120℃ for 4 hours to obtain APTES / MCM-41 for later use.

[0061] In the above process, the mass ratio of MCM-41 molecular sieve, anhydrous toluene, and aminopropyltriethoxysilane used is 1:8-9:0.12-0.15.

[0062] In the above-mentioned washing process using anhydrous ethanol, the volume of anhydrous ethanol used each time is 50% to 60% of the volume of anhydrous toluene.

[0063] In the above process, the ethoxy group in aminopropyltriethoxysilane undergoes a nucleophilic substitution reaction with the silanol group on the surface of MCM-41 to generate a stable silicon-oxygen covalent bond, which fixes the amino group on the support surface through the three methylene chains in the aminopropyltriethoxysilane molecule.

[0064] The amino group is introduced into the catalyst because its weak basicity can precisely activate the hydroxyl group of alcohol to generate allyl alcohol anions, and it will not cause the allyl alcohol dehydration side reaction as strong basic catalysts do.

[0065] S3: APTES / MCM-41 was dispersed in a ZrCl4 ethanol solution. The system was heated to 60°C and stirred for 4 hours. The solid was collected by filtration and washed three times with anhydrous ethanol. Then, it was dried under vacuum at 120°C for 6 hours to obtain the core product APTES-Zr. 4+ / MCM-41.

[0066] The concentration of the ZrCl4 ethanol solution is 0.1 mol / L, and the volume ratio of the ZrCl4 ethanol solution to the anhydrous toluene in step S2 is 5:4.

[0067] In the process of washing with anhydrous ethanol, the volume of anhydrous ethanol used each time is the same as the amount of anhydrous ethanol used in step S2.

[0068] In the above steps, Zr is further introduced into APTES / MCM-41. 4+ Zr 4+ It is a Lewis acid and can accept the lone pair electrons of the amino N atom in APTES to form a coordination structure.

[0069] Among them, the introduced Zr 4+ It can coordinate with the oxygen group of dipropylene carbonate, reduce the electron cloud density of the carbon atom of the ester group, enhance its electrophilicity, promote the nucleophilic attack of the diethylene glycol anion, and thus significantly shorten the reaction time.

[0070] S4: Transfer kernel artifacts APTES-Zr 4+ / MCM-41 was dispersed in anhydrous ethanol, an epoxy-containing silane coupling agent was added, and the mixture was stirred at 50°C for 2 hours. The solid was collected by filtration and dried at 100°C for 3 hours to obtain a core containing an interface modification layer.

[0071] Among them, the epoxy-containing silane coupling agent is γ-glycidoxypropyltrimethoxysilane (KH-560).

[0072] Among them, APTES-Zr 4+ The mass ratio of / MCM-41, anhydrous ethanol, and epoxy-containing silane coupling agent is 20:80:1.

[0073] The purpose of the above steps is to form an interface layer with adhesive and transition functions between the core and the shell. The epoxy group in the KH-560 molecule undergoes a nucleophilic ring-opening reaction with the amino group on the core surface to generate a linear structure containing hydroxyl groups. The hydroxyl groups further undergo a condensation reaction with the residual silanol groups on the core surface to form a bicovalent connection between the core and KH-560.

[0074] In addition, the siloxane chain in the KH-560 molecule, as a hydrophobic group, can bind tightly to the shell, thereby effectively reducing the interfacial tension between the core and the shell, increasing the binding force between the core and the shell, thus reducing the catalyst breakage rate during use and increasing the number of catalyst cycles.

[0075] S5: The core containing the interface-modified layer was dispersed in a mixture of ethanol and water. A mixture of tetraethyl orthosilicate and phenyltriethoxysilane was added dropwise to the mixture. The pH of the system was adjusted to 4-5 using 0.1 mol / L hydrochloric acid. The system was heated to 30°C and stirred for 3 hours, then the temperature was increased to 60°C and stirred for 6 hours. The solid was then collected by filtration and washed three times with anhydrous ethanol. Finally, it was calcined at 150°C for 2 hours to obtain the core-shell catalyst Ph-SiO2@KH-560@APTES-Zr. 4+ / MCM-41.

[0076] The volume ratio of ethanol to water is 3:1, and the volume ratio of the mixture of ethanol and water, tetraethyl orthosilicate, and phenyltriethoxysilane is 10:4:1.

[0077] The mass-to-volume ratio of the core containing the interface modification layer to phenyltriethoxysilane is 1 g: 5 ml.

[0078] In the process of washing with anhydrous ethanol, the volume of anhydrous ethanol used each time is the same as the amount of anhydrous ethanol used in step S2.

[0079] During the above steps, under acidic conditions of pH 4 to 5, the ethoxy groups in tetraethyl orthosilicate and phenyltriethoxysilane undergo hydrolysis to generate silanetetrol and phenylsilanetriol. The silanetetrol and phenylsilanetriol undergo a condensation reaction to form a phenyl-containing SiO2 network structure, and the phenyl groups are uniformly distributed in the network.

[0080] In addition, calcination at 150°C can remove residual ethanol, unhydrolyzed silanes and other organic matter from the shell, and make the SiO2 network structure denser, thereby improving the mechanical strength of the shell.

[0081] The phenyl groups uniformly distributed in the network act as pore regulators, forming mesopores of about 1 nm during the polymerization process. This creates a molecular barrier, allowing only small molecule reactants to enter the core while blocking large molecule reactants from entering the outer shell. This prevents the active sites of the core from being covered. For example, the outer molecular barrier can prevent allyl double bonds from entering the core and contacting Zr. 4+ This avoids the double bond addition side reaction of the allyl group.

[0082] The core-shell catalyst contains amino groups and Zr. 4+ The synergistic effect of the phenyl shell and the weakly basic site in the core significantly reduces side reactions such as allyl alcohol dehydration and double bond addition, thereby effectively improving product purity.

[0083] In addition, the good structural stability of core-shell catalysts can increase the number of cycles. See [link to relevant documentation]. Figure 1 , Figure 2 The core-shell catalyst initially prepared had a high degree of shell integrity. After three repeated uses and sieving, some catalyst particles developed cracks and showed signs of detachment, but most catalyst particles maintained a high degree of shell integrity, which did not affect continued use. This proves that the core-shell catalyst can meet the requirements for recycling, has a good reuse effect, and can effectively reduce production costs.

[0084] Step 2

[0085] The dipropylene carbonate mixture at the bottom of the tower is sent to a plate and frame filter press for solid-liquid separation. The solution is collected for later use. The solid catalyst is washed twice with ethanol and then transferred to a hot air dryer. It is dried at 100-120°C for 1 hour. After drying, the fine powder in the solid catalyst is removed by sieving with a sieve with a pore size of 4μm. The remaining catalyst is collected for later use.

[0086] In each cleaning of the catalyst, the mass ratio of ethanol to catalyst is 25-30:1.

[0087] In the above steps, ethanol is used to remove components such as methanol, dimethyl carbonate, and dipropylene carbonate from the solid catalyst. Then, a hot air dryer is used to dry the catalyst. Undamaged solid catalyst is selected by sieving and collected for later use.

[0088] In this process, the separated reaction liquid contains the intermediate product dipropylene carbonate, which is used for subsequent distillation and purification steps. At the same time, the solid catalyst is recovered, realizing the recycling of the catalyst. The drying process after ethanol washing uses a temperature range of 100-120℃. On the one hand, it can effectively remove the residual ethanol on the surface of the solid catalyst. On the other hand, this temperature range will not damage the structure of the catalyst, avoid the loss of active sites and the resulting decrease in catalyst activity, and realize the reactivation of the catalyst, which is beneficial to improving the subsequent catalytic efficiency of the catalyst.

[0089] Step 3

[0090] The solution obtained in step 2 is fed into a vacuum distillation column for the first distillation to remove methanol from the solution and condense it for later use. The remaining solution is heated for the second distillation to remove dimethyl carbonate from the solution and condense it for later use, resulting in the remaining solution of dipropylene carbonate for later use.

[0091] The parameters for the first distillation are: pressure 0.1 MPa and temperature 63–68 °C, and the parameters for the second distillation are: pressure 0.05 MPa and temperature 88–92 °C.

[0092] In this step, the components in the mixture are separated by utilizing the correspondence between vacuum distillation and the boiling point of the liquid. Methanol and dipropylene carbonate have different boiling points, and the difference in boiling points is significant under different pressures. By controlling different pressure and temperature conditions, methanol and dimethyl carbonate can be separated from the solution sequentially.

[0093] Specifically, at a pressure of 0.1 MPa, the boiling point of methanol is 63–68 °C. At this temperature, methanol vaporizes and is distilled off. This temperature range allows methanol to fully vaporize while avoiding the excessive vaporization of other components in the mixture, ensuring the purity of methanol and enabling effective separation and recovery. Subsequently, the pressure is reduced to 0.05 MPa, and the boiling point of dimethyl carbonate drops to 88–92 °C, thus allowing it to fully vaporize and be distilled off. In the above distillation process, by controlling the temperature and pressure, methanol and dimethyl carbonate are separated sequentially. Because dipropylene carbonate has a relatively high boiling point, it remains in the solution.

[0094] By separating and recovering methanol and dimethyl carbonate through distillation, the raw materials can be utilized as resources, reducing waste. At the same time, impurities in the reaction system are removed to prevent them from interfering with subsequent reactions and to ensure product quality.

[0095] Step 4

[0096] Diethylene glycol and dipropylene carbonate from step 3 are mixed at a molar ratio of 1:2.2-2.4 and fed into a batch reactor. A core-shell catalyst is added to the reactor, and the reaction temperature is controlled at 80-105℃. After reacting for 4-5 hours under normal pressure, a mixture containing allyl diethylene glycol dicarbonate is obtained.

[0097] The amount of core-shell catalyst added is 3% to 5% of the mass of diethylene glycol.

[0098] In the above steps, diethylene glycol and dipropylene carbonate undergo the following reaction under the action of a catalyst:

[0099]

[0100] Diethylene glycol and dipropylene carbonate undergo transesterification under the action of a core-shell catalyst to produce allyl diethylene glycol dicarbonate and propenol.

[0101] The core of a core-shell catalyst is in amino and Zr 4+ Under the synergistic effect, amino groups activate the hydroxyl groups of diethylene glycol, Zr 4+ The oxygen coordination with the ester group of dipropylene carbonate enhances the positive charge of the ester group carbon atom, promotes the nucleophilic attack of the diethylene glycol anion on the ester group carbon atom, and accelerates the reaction rate.

[0102] In addition, the steric hindrance of the phenyl shell can prevent large molecules from entering the core, such as reducing side reactions like allyl double bond addition reactions, thereby improving the selectivity of the reaction and increasing the purity of the product.

[0103] In the above reaction process, adding an excess of dipropylene carbonate can improve the conversion rate of diethylene glycol, ensure that diethylene glycol reacts fully to form allyl diethylene glycol dicarbonate, reduce unreacted diethylene glycol residue, and reduce the difficulty of subsequent separation and purification. The excess dipropylene carbonate can be recovered and reused in subsequent steps. The catalyst dosage of 3% to 5% can achieve the best catalytic effect, which can balance the reaction rate and ensure that by-products are not generated due to excessive reaction.

[0104] The reaction temperature is controlled at 80–105°C. This temperature range can effectively exert the activity of the core-shell catalyst and accelerate the transesterification reaction rate. The total reaction time is 4–5 hours. In order to ensure that the transesterification reaction is fully carried out, the diethylene glycol is converted into the target product as much as possible.

[0105] Step 5

[0106] The mixture obtained in step 4 is sent to a vacuum distillation column for the first distillation to remove allyl alcohol from the mixture and condense it for later use. Then, the mixture is heated and vacuumed for the second distillation to remove dipropylene carbonate from the mixture, yielding crude allyl diethylene glycol dicarbonate.

[0107] The parameters for the first distillation are: pressure 0.1 MPa, temperature 93–100 °C; and the parameters for the second distillation are: pressure 0.015 MPa, temperature 130–135 °C, and distillation time 2–3 hours.

[0108] In this step, the different boiling points of the components in the mixture and their variation with pressure are utilized to achieve separation of the components by controlling different pressure and temperature conditions. At a pressure of 0.1 MPa, the boiling point of allyl alcohol drops to 93-100°C. At this point, the temperature of the mixture is raised to this range, and allyl alcohol vaporizes and is distilled off. Subsequently, the pressure is reduced to 0.015 MPa and the temperature is increased to 130-135°C, and the boiling point of dipropylene carbonate drops to this range, thus distilling it off. Allyl diethylene glycol dicarbonate, due to its higher boiling point, remains at the bottom of the column as a crude product.

[0109] Step 6

[0110] The crude allyl diethylene glycol dicarbonate obtained in step 5 was subjected to vacuum distillation, with the pressure controlled at 20-80 Pa, the temperature at 130-140 °C, and the distillation time at 1 hour, to obtain the final product allyl diethylene glycol dicarbonate.

[0111] The crude allyl diethylene glycol dicarbonate still contains trace amounts of low-boiling-point impurities, such as incompletely separated allyl alcohol, dipropylene carbonate, and possible trace amounts of polymeric byproducts, such as double bond addition polymers. Therefore, further purification of the crude allyl diethylene glycol dicarbonate is required.

[0112] Because allyl diethylene glycol dicarbonate has a high boiling point, atmospheric distillation at high temperatures can cause it to decompose, leading to ester bond breakage or double bond oxidation, which damages the molecular structure and reduces product purity and performance. However, under high vacuum conditions of 20–80 Pa, the boiling point of allyl diethylene glycol dicarbonate can be reduced to 130–140 °C. This temperature allows it to fully vaporize while remaining far below its thermal decomposition threshold, thus avoiding thermal damage. At the same time, low-boiling-point impurities such as allyl alcohol remaining in the crude product will preferentially vaporize before reaching this temperature range, while trace amounts of high-molecular-weight byproducts generated by side reactions are difficult to vaporize due to their high boiling points and will remain in the distillation residue, thereby achieving efficient separation of the final product from impurities.

[0113] In addition, compared with other purification methods such as column chromatography and solvent extraction, high vacuum distillation does not require the introduction of additional solvents, avoiding solvent residues and reducing subsequent solvent recovery costs. At the same time, the target product vaporized during distillation can be directly collected by condensation without complicated separation steps, making the operation simple and the yield stable, thus balancing purity and economy.

[0114] To facilitate a further understanding of the present invention, several embodiments and comparative examples are provided below for reference.

[0115] Example 1

[0116] Catalyst preparation:

[0117] S1: Place 20g of MCM-41 molecular sieve in a muffle furnace, heat it to 500℃ at a rate of 5℃ / min, keep it at that temperature for 4 hours, and then cool it to room temperature with the furnace for later use.

[0118] S2: The calcined MCM-41 molecular sieve was dispersed in 160g of anhydrous toluene, and then 3g of aminopropyltriethoxysilane was added. The mixture was heated to 80℃ and reacted for 6 hours. After the reaction was completed, the solid was collected by filtration and washed three times with 240g of anhydrous ethanol. Then it was dried under vacuum at 120℃ for 4 hours to obtain APTES / MCM-41 for later use.

[0119] S3: The above APTES / MCM-41 was dispersed in 128 ml of 0.1 mol / L ZrCl4 ethanol solution. The system was heated to 60 °C and stirred for 4 hours. The solid was collected by filtration and washed three times with 240 g of anhydrous ethanol in equal portions. Then it was dried under vacuum at 120 °C for 6 hours to obtain the core product APTES-Zr. 4+ / MCM-41.

[0120] S4: The 20g kernel product APTES-Zr 4+ / MCM-41 was dispersed in 80g of anhydrous ethanol, and 1g of epoxy-containing silane coupling agent was added. The mixture was then stirred at 50°C for 2 hours. The solid was collected by filtration and dried at 100°C for 3 hours to obtain a core containing an interface modification layer.

[0121] S5: 10g of the core containing the interface modification layer was dispersed in 500ml of a mixture of ethanol and water with a volume ratio of 3:1. A mixture of 200ml tetraethyl orthosilicate and 50ml phenyltriethoxysilane was added dropwise to the mixture. The pH of the system was adjusted to 4.5 using 0.1mol / L hydrochloric acid. The system was heated to 30℃ and stirred for 3 hours, then the temperature was further increased to 60℃ and stirred for 6 hours. The solid was then collected by filtration and washed three times with 240g of anhydrous ethanol. The solid was then calcined at 150℃ for 2 hours to obtain the core-shell catalyst Ph-SiO2@KH-560@APTES-Zr. 4+ / MCM-41.

[0122] Synthesis of allyl diethylene glycol dicarbonate:

[0123] Step 1

[0124] 1 mol of allyl alcohol and 3 mol of dimethyl carbonate were fed into a reactor preheated to 50°C. 2 g of core-shell catalyst was added to the reactor. The reaction temperature of the reactor was controlled at 85°C. The stirring rate of the reactor was controlled at 80 r / min. The reactor was refluxed for 7 hours. After the reaction was completed, a dipropylene carbonate mixture was obtained.

[0125] Step 2

[0126] The dipropylene carbonate mixture at the bottom of the tower was transferred to a plate and frame filter press for solid-liquid separation. The solution was collected for later use. The solid catalyst was washed twice with 150g of ethanol and transferred to a hot air dryer. It was dried at 110℃ for 1 hour. After drying, the fine powder in the solid catalyst was removed by sieving with a sieve with a pore size of 4μm. The remaining catalyst was collected for later use.

[0127] Step 3

[0128] The solution obtained in step 2 is fed into a vacuum distillation column for the first distillation. Methanol in the solution is distilled off under a pressure of 0.1 MPa and a temperature of 65°C and then condensed and recovered for later use. The remaining solution is then subjected to a second distillation under a pressure of 0.05 MPa and a temperature of 90°C to distill off dimethyl carbonate in the solution and then condensed and recovered for later use, yielding dipropylene carbonate as the remaining solution for later use.

[0129] Step 4

[0130] 0.42 mol of diethylene glycol and dipropylene carbonate from step 3 were mixed and fed into a batch reactor. 6 g of core-shell catalyst was added to the reactor. The reaction temperature was controlled at 95 °C. After reacting for 4.5 hours under normal pressure, a mixture containing allyl diethylene glycol dicarbonate was obtained.

[0131] Step 5

[0132] The mixture obtained in step 4 is sent to a vacuum distillation column for the first distillation. Allyl alcohol in the mixture is distilled off under a pressure of 0.1 MPa and a temperature of 93°C and condensed for recovery. Then, the mixture is heated and vacuumed for the second distillation. Distillation is carried out for 2 hours under a pressure of 0.015 MPa and a temperature of 130°C to distill off dipropylene carbonate in the mixture, yielding crude allyl diethylene glycol dicarbonate.

[0133] Step 6

[0134] The crude allyl diethylene glycol dicarbonate obtained in step 5 was subjected to vacuum distillation at a pressure of 50 Pa, a temperature of 135 °C, and a distillation time of 1 hour to obtain the final product, allyl diethylene glycol dicarbonate.

[0135] Example 2

[0136] This embodiment adjusts the amount of core-shell catalyst in step 1 of the allyl diethylene glycol dicarbonate synthesis process based on Example 1. Specifically:

[0137] Step 1

[0138] 1 mol of allyl alcohol and 3 mol of dimethyl carbonate were fed into a reactor preheated to 50°C. 2.5 g of core-shell catalyst was added to the reactor. The reaction temperature of the reactor was controlled at 85°C. The stirring rate of the reactor was controlled at 80 r / min. The reactor was refluxed for 7 hours. After the reaction was completed, a dipropylene carbonate mixture was obtained.

[0139] The remaining steps and processes are exactly the same as in Example 1.

[0140] Example 3

[0141] This embodiment is based on Example 1, but adjusts the amount of core-shell catalyst in step 4 of the allyl diethylene glycol dicarbonate synthesis process, specifically as follows:

[0142] Step 4

[0143] 0.42 mol of diethylene glycol and dipropylene carbonate from step 3 were mixed and fed into a batch reactor. 8 g of core-shell catalyst was added to the reactor. The reaction temperature was controlled at 95 °C. After reacting for 4.5 hours under normal pressure, a mixture containing allyl diethylene glycol dicarbonate was obtained.

[0144] The remaining steps and processes are exactly the same as in Example 1.

[0145] Example 4

[0146] This embodiment adjusts the parameters of the two vacuum distillations in step 5 based on embodiment 1, specifically as follows:

[0147] Step 5

[0148] The mixture obtained in step 4 is sent to a vacuum distillation column for the first distillation. Allyl alcohol in the mixture is distilled off under a pressure of 0.1 MPa and a temperature of 100°C and condensed for recovery. Then, the mixture is heated and the pressure is reduced for the second distillation. Dipropylene carbonate in the mixture is distilled off under a pressure of 0.015 MPa and a temperature of 135°C for 3 hours to obtain crude allyl diethylene glycol dicarbonate.

[0149] The remaining steps and processes are exactly the same as in Example 1.

[0150] Comparative Example 1

[0151] This comparative example is based on Example 1, with adjustments made to the catalyst preparation process, specifically:

[0152] Catalyst preparation:

[0153] S1: Place 20g of MCM-41 molecular sieve in a muffle furnace, heat it to 500℃ at a rate of 5℃ / min, keep it at that temperature for 4 hours, and then cool it to room temperature with the furnace for later use.

[0154] S2: The calcined MCM-41 molecular sieve was dispersed in 160g of anhydrous toluene, and then 3g of aminopropyltriethoxysilane was added. The mixture was heated to 80℃ and reacted for 6 hours. After the reaction was completed, the solid was collected by filtration and washed three times with 240g of anhydrous ethanol. Then it was dried under vacuum at 120℃ for 4 hours to obtain APTES / MCM-41 for later use.

[0155] S3: The above APTES / MCM-41 was dispersed in 128 ml of 0.1 mol / L ZrCl4 ethanol solution. The system was heated to 60 °C and stirred for 4 hours. The solid was collected by filtration and washed three times with 240 g of anhydrous ethanol in equal portions. Then it was dried under vacuum at 120 °C for 6 hours to obtain the core product APTES-Zr. 4+ / MCM-41.

[0156] The core product obtained above was used to replace the core-shell catalyst in the synthesis of allyl diethylene glycol dicarbonate in an equal amount, and the remaining steps and processes were exactly the same as in Example 1.

[0157] Comparative Example 2

[0158] This comparative example is based on Example 1, with adjustments made to the catalyst preparation process, specifically:

[0159] Catalyst preparation:

[0160] S1: Place 20g of MCM-41 molecular sieve in a muffle furnace, heat it to 500℃ at a rate of 5℃ / min, keep it at that temperature for 4 hours, and then cool it to room temperature with the furnace for later use.

[0161] S2: The calcined MCM-41 molecular sieve was dispersed in 160g of anhydrous toluene, and then 3g of aminopropyltriethoxysilane was added. The mixture was heated to 80℃ and reacted for 6 hours. After the reaction was completed, the solid was collected by filtration and washed three times with 240g of anhydrous ethanol. Then it was dried under vacuum at 120℃ for 4 hours to obtain APTES / MCM-41 for later use.

[0162] S3: The above APTES / MCM-41 was dispersed in 128 ml of 0.1 mol / L ZrCl4 ethanol solution. The system was heated to 60 °C and stirred for 4 hours. The solid was collected by filtration and washed three times with 240 g of anhydrous ethanol in equal portions. Then it was dried under vacuum at 120 °C for 6 hours to obtain the core product APTES-Zr. 4+ / MCM-41.

[0163] S4: 10g of the core product was dispersed in 500ml of a mixture of ethanol and water with a volume ratio of 3:1. A mixture of 200ml tetraethyl orthosilicate and 50ml phenyltriethoxysilane was added dropwise to the mixture. The pH of the system was adjusted to 4.5 using 0.1mol / L hydrochloric acid. The system was heated to 30℃ and stirred for 3 hours, then the temperature was further increased to 60℃ and stirred for 6 hours. The solid was then collected by filtration and washed three times with 240g of anhydrous ethanol. The solid was then calcined at 150℃ for 2 hours to obtain the core-shell catalyst Ph-SiO2@APTES-Zr. 4+ / MCM-41.

[0164] The core-shell catalyst obtained above was used to replace the core-shell catalyst in the synthesis of allyl diethylene glycol dicarbonate in an equal amount, and the remaining steps and processes were exactly the same as in Example 1.

[0165] The methods and steps of the above examples and comparative examples were used to prepare allyl diethylene glycol dicarbonate, and the yield and purity of the final product allyl diethylene glycol dicarbonate were calculated respectively.

[0166] In addition, in the same embodiment or comparative example, the catalyst that was just prepared and the catalyst that was recycled for the 8th time were used to prepare allyl diethylene glycol dicarbonate, and the product yield and purity were calculated respectively.

[0167] The statistical data results are shown in the table below:

[0168]

[0169] Based on the above data, the following conclusions can be drawn:

[0170] Examples 1-4 all employ core-shell catalysts with intact structures, where the core amino group and Zr... 4+ The catalyst synergistically accelerates the transesterification reaction, the phenyl shell blocks the double bond addition side reaction, and the interfacial layer enhances the catalyst stability. Therefore, the yield of the catalyst used for the first time is higher than 85%. Comparative Example 1 has no shell. Without the protection of the shell, the active sites of the core are directly exposed, which easily triggers side reactions such as allyl alcohol dehydration and ester hydrolysis, resulting in a reduced amount of the target product. The yield of the catalyst used for the first time is only 85.7%. Comparative Example 2 has no interfacial layer. The binding force between the core and the shell is weak. During the reaction, part of the shell falls off, and the active sites are exposed, triggering side reactions. The yield is lower than that of Examples 1 to 4.

[0171] In Example 2, the amount of catalyst used in step 1 was slightly higher than that in Example 1. The increased amount of catalyst led to more active sites and a more complete transesterification reaction. In Example 3, the amount of catalyst used in step 4 was slightly higher than that in Example 1. Similarly, the increased number of active sites resulted in a more complete reaction. In Example 4, the first distillation temperature was increased to 100°C, which resulted in more thorough separation of allyl alcohol and reduced its interference with subsequent reactions. Therefore, the product yield was slightly higher than that in Example 1.

[0172] In Examples 1-4, the presence of the catalyst interface layer reduced the interfacial tension between the catalyst core and the outer shell, resulting in strong catalyst structural stability and a low breakage rate after 8 cycles. Therefore, the impact on yield and purity was minimal, with purity decreasing by only 0.1% to 0.5%. In Comparative Example 1, there was no outer shell, and the core directly contacted the reaction system. The active sites were easily covered by byproducts, leading to a significant decrease in yield and purity after 8 cycles. In Comparative Example 2, the absence of an interface layer caused the outer shell to easily detach during cycling, resulting in severe loss of active sites and incomplete reaction, thus significantly reducing the yield.

[0173] The embodiments described above are not exhaustive, nor do they limit the invention to any specific embodiments. Clearly, many modifications and variations can be made based on the above description. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to effectively utilize the invention and its modifications. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention.

Claims

1. A production process for allyl diethylene glycol dicarbonate, characterized in that, Specifically, the following steps are included: Step 1: Allyl alcohol and dimethyl carbonate undergo a first transesterification reaction in the presence of a core-shell catalyst to produce a dipropylene carbonate mixture. Step 2: Perform solid-liquid separation on the mixture, recover the catalyst and collect the liquid; Step 3: Perform two vacuum distillations on the liquid to separate methanol and dimethyl carbonate in sequence, thereby obtaining dipropylene carbonate; Step 4: The dipropylene carbonate and diethylene glycol undergo a second transesterification reaction in the presence of the core-shell catalyst to generate a mixture containing allyl diethylene glycol dicarbonate. Step 5: The mixture is subjected to vacuum distillation to separate allyl alcohol and dipropylene carbonate in sequence, yielding crude allyl diethylene glycol dicarbonate. Step 6: The crude product is subjected to high-vacuum distillation to obtain purified allyl diethylene glycol dicarbonate; The core-shell catalyst comprises a three-layer structure from the inside out: The core is modified with aminopropyltriethoxysilane and loaded with Zr. 4+ MCM-41 molecular sieve; An interface modification layer is connected to the core via an epoxy-containing silane coupling agent; The outer shell is a mesoporous SiO2 structure containing phenyl groups; The preparation method of the core-shell catalyst includes the following steps: S1: High-temperature calcination treatment of MCM-41 molecular sieve; S2: Modification of calcined MCM-41 using aminopropyltriethoxysilane; S3: Treat the modified MCM-41 with ZrCl4 ethanol solution to introduce Zr 4+ The kernel product is obtained; S4: React the core product with an epoxy-containing silane coupling agent to form an interface modification layer; S5: Under acidic conditions, tetraethyl orthosilicate and phenyltriethoxysilane are co-condensed on a core containing an interface-modified layer to form a shell, and the core-shell catalyst is obtained after calcination.

2. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, In step 1, the molar ratio of allyl alcohol to dimethyl carbonate is 1:2.5 to 3.5; The amount of the core-shell catalyst added is 3% to 5% of the mass of allyl alcohol; In step 1, the reaction temperature is 80–90°C and the reaction time is 6–8 hours.

3. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, The reaction in step 1 is carried out under stirring conditions at a stirring rate of 80 r / min.

4. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, In step 4, the molar ratio of diethylene glycol to dipropylene carbonate is 1:2.2 to 2.4, the amount of the core-shell catalyst added is 3% to 5% of the mass of diethylene glycol, the reaction temperature is 80 to 105°C, and the reaction time is 4 to 5 hours.

5. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, In step 6, the pressure of high-vacuum distillation is 20-80 Pa, the temperature is 130-140 °C, and the distillation time is 1 hour.

6. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, The conditions for high-temperature calcination in step S1 are: heating to 500℃ at a rate of 5℃ / min and holding at that temperature for 4 hours; In step S5, the pH value of the acidic conditions is 4-5, the calcination temperature is 150℃, and the calcination time is 2 hours.

7. The production process of allyl diethylene glycol dicarbonate as described in claim 1, characterized in that, In step S2, the mass ratio of MCM-41 molecular sieve, anhydrous toluene, and aminopropyltriethoxysilane is 1:8-9:0.12-0.

15. The epoxy-containing silane coupling agent mentioned in step S4 is γ-glycidoxypropyltrimethoxysilane.

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