A schiff base catalyst, a preparation method thereof and a preparation method of allyl glycidyl ether
By using a two-component catalytic system consisting of an asymmetric Schiff base catalyst and a phase transfer catalyst, the problems of long production cycle and high cost in the preparation of allyl glycidyl ether were solved, and a highly selective and efficient ring-opening reaction was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2023-12-11
- Publication Date
- 2026-07-10
AI Technical Summary
Existing methods for preparing allyl glycidyl ethers suffer from problems such as long production cycles, short catalyst lifetimes, difficulty in separation and regeneration, numerous byproducts, difficult purification, and high production costs.
A two-component catalytic system consisting of an asymmetric Schiff base catalyst and a phase transfer catalyst was used to catalyze the preparation of allyl glycidyl ether. The asymmetric structure of the Schiff base complex and the sterically hindered quaternary ammonium salt were utilized to improve the selectivity and efficiency of the ring-opening reaction.
It significantly improved the selectivity of the epichlorohydrin ring-opening reaction, shortened the reaction cycle, reduced the selectivity of by-products, and lowered production costs.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of catalysts, and more particularly to a catalytic system for allyl glycidyl ether, and a method for preparing allyl alcohol glycidyl ether. Background Technology
[0002] Allyl glycidyl ether (AGE) is an important organic chemical raw material containing both unsaturated double bonds and epoxy groups, making it suitable as an organic synthesis intermediate and polymerization monomer. It is widely used in epoxy resins and silane coupling agents. It is also commonly used as an organosilicon surfactant.
[0003] There are two industrially available methods for preparing allyl glycidyl ether (AGE): ring-opening and ring-closing processes, and phase transfer catalysis. The ring-opening and ring-closing process uses allyl alcohol and epichlorohydrin as raw materials. Under the catalysis of Lewis acids (sulfuric acid, tin tetrachloride, boron trifluoride diethyl ether, etc.), the intermediate 1-chloro-2-hydroxy-3-allyloxypropane is first synthesized, and then cyclized under alkaline conditions to obtain the product. For example, patent CN106749109A uses boron trifluoride diethyl ether as a catalyst for the ring-opening reaction; patent CN103145648A further uses boron trifluoride supported on activated carbon as a catalyst for the ring-opening reaction; and patent CN1927851A uses perchlorate as a catalyst for the ring-opening reaction. The process described in the aforementioned patent has high yield and selectivity, but it has technical disadvantages such as long production cycle, short catalyst life, and difficulty in separation and regeneration. The phase transfer catalytic process uses allyl alcohol and epichlorohydrin as raw materials to directly produce AGE under the action of alkali and phase transfer catalyst. This method has the advantages of mild reaction conditions and easy operation, and it is easy to realize industrial production. However, the excessive by-products make the purification of this process more difficult and the production cost higher.
[0004] To overcome the shortcomings of existing technologies, it is necessary to design a highly efficient catalytic system and preparation method for the production of allyl glycidyl ethers. Summary of the Invention
[0005] To address the aforementioned problems in the existing technology, the present invention first provides an asymmetric Schiff base catalyst, which, in combination with a phase transfer catalyst, forms a two-component catalytic system with advantages such as high selectivity and high activity.
[0006] Secondly, the present invention provides a method for preparing the above-mentioned asymmetric Schiff base catalyst.
[0007] Furthermore, the present invention also provides an application of the aforementioned two-component catalytic system, which can be used to catalyze the preparation of allyl glycidyl ethers, significantly improving the selectivity of the epichlorohydrin ring-opening reaction, reducing the by-product selectivity, and shortening the ring-opening reaction cycle.
[0008] To achieve the objectives of this invention, the following technical solution is adopted:
[0009] On one hand, the present invention provides a Schiff base catalyst comprising an ethylenediamine framework and an asymmetric salicylaldehyde structure, and one or more of Sn, Al, and Fe central atoms.
[0010] As a preferred embodiment, the structural formula of the Schiff base catalyst is shown below:
[0011]
[0012] On the other hand, the present invention also provides a method for preparing the above-mentioned Schiff base catalyst, comprising the following steps:
[0013] a) Ethylenediamine and 3,5-di-tert-butylsalicylaldehyde and 5-tert-butylsalicylaldehyde are dissolved in an organic solvent, stirred, and reacted. The reaction system is placed in an ice-water bath for cooling, and a large amount of solid will precipitate out. The mixture is filtered and the filter cake is washed with ice-cold ethanol and dried to obtain Schiff base ligands.
[0014] b): Dissolve the above ligand in dichloromethane, add the metal salt, stir, remove the dichloromethane, and the resulting solid is the Schiff base metal complex.
[0015] In a specific example of the present invention, the 3,5-di-tert-butylsalicylaldehyde or 5-tert-butylsalicylaldehyde is 1-1.1 times the molar amount of ethylenediamine, for example, 1.0 times, 1.05 times, or 1.1 times, preferably 1.0-1.05 times.
[0016] In a specific example of the present invention, the organic solvent in step a) is selected from one or more of anhydrous methanol, anhydrous ethanol, etc., preferably anhydrous ethanol.
[0017] Preferably, in step a), the amount of the organic solvent used, in terms of the concentration of 3,5-di-tert-butylsalicylaldehyde therein, is 0.05-0.1 g / ml, for example 0.05 g / ml, 0.08 g / ml, 0.1 g / ml, and more preferably 0.07-0.08 g / ml.
[0018] In a specific example of the present invention, in step a), the reaction temperature is 30-80°C, for example 30°C, 50°C, 70°C, 80°C, preferably 30-50°C; the time is 3-12h, for example 4h, 6h, 8h, 12h, preferably 5-8h.
[0019] In a specific example of the present invention, in step b), the metal salt is one or more of SnCl4, AlCl3, and FeCl3, preferably SnCl4, and the equivalent amount is equal to the ligand equivalent amount.
[0020] In a specific example of the present invention, in step b), the reaction temperature is 30-80°C, for example 30°C, 50°C, 70°C, or 80°C, preferably 30-50°C, and the reaction time is 3-12 hours, for example 3 hours, 6 hours, or 8 hours.
[0021] 12h, preferably 3-5h.
[0022] In another aspect, the present invention also provides a phase transfer catalyst in combination with the Schiff base metal complex, such as one or more of quaternary ammonium salts such as N,N-dimethyl-1-adamantaneamine chloride, triethylbenzylammonium chloride, tetrabutylammonium chloride, and tetramethylammonium chloride, preferably N,N-dimethyl-1-adamantaneamine.
[0023] The present invention also provides the application of the two-component catalytic system composed of the Schiff base metal complex and the phase transfer catalyst in the ring-opening reaction of epoxides and halogenated epoxides, preferably in the ring-opening reaction of epoxides such as ethylene oxide, propylene oxide, and epichlorohydrin, especially in the ring-opening reaction of epichlorohydrin to prepare allyl glycidyl ether.
[0024] In a preferred embodiment of the present invention, a method for preparing allyl glycidyl ether is provided, comprising the following steps:
[0025] (1) A catalytic system consisting of Schiff base catalyst and phase transfer catalyst is added to allyl alcohol to obtain raw material 1; raw material 1 and epichlorohydrin are continuously fed into a tubular reactor, and the molar ratio of the two is 3-5:1. The reactor is subjected to ring-opening reaction at 30-50℃, and the residence time is 0.5-3h. The reaction liquid is continuously collected to obtain allyl chlorohydrin ether intermediate.
[0026] (2) Add an alkaline aqueous solution to the allyl chlorohydrin ether intermediate collected in step (1), wherein the molar ratio of sodium hydroxide to epichlorohydrin is 0.9-1.1 / 1, the ring-closing reaction time is 3-5 h, and the reaction temperature is 30-50 °C, to obtain the crude product of allyl glycidyl ether.
[0027] (3) After desalting the crude product in step (2), it is distilled in a distillation column to obtain the finished product.
[0028] In a specific embodiment of the present invention, the structure of the allyl glycidyl ether is as shown in formula (1):
[0029]
[0030] In a specific embodiment of the present invention, the molar ratio of allyl alcohol to epichlorohydrin in step (1) is 3-5:1, for example 3:1, 4:1, 5:1, preferably 3:1.
[0031] In a specific embodiment of the present invention, the amount of Schiff base catalyst added in step (1) is 0.05-0.2% of the mass of allyl alcohol, for example, 0.05%, 0.08%, 0.1%, 0.2%, preferably 0.08-0.1%. The molar ratio of Schiff base catalyst to phase transfer catalyst is 1:1-5, for example, 1:1, 1:2, 1:3, 1:4, 1:5, preferably 1:1-1:2.
[0032] In a specific embodiment of the present invention, the allyl alcohol and epichlorohydrin in step (1) are continuously mixed in a certain proportion and then continuously fed into the tube reactor. The residence time of the material in the tube reactor is 0.5-2h, preferably 1-1.2h.
[0033] In a specific embodiment of the present invention, the ring-opening reaction in step (1) is carried out at a temperature of 30-50°C, such as 30°C, 40°C, or 50°C, preferably 30-40°C, and for a reaction time of 0.5-2h, such as 0.5h, 1h, 1.5h, or 2h, preferably 1-1.5h.
[0034] In a specific embodiment of the present invention, the alkaline aqueous solution in step (2) is an aqueous solution of a metal hydroxide, preferably one or more aqueous solutions of sodium hydroxide, potassium hydroxide, etc.; preferably, the mass concentration of the alkali in the alkaline aqueous solution is 30-35%, for example 30%, 33%, 35%.
[0035] In a specific embodiment of the present invention, the molar ratio of the alkali to the epichlorohydrin in the alkaline aqueous solution in step (2) is 0.9-1.1:1, for example 0.9:1, 1:1, or 1.5:1.
[0036] In a specific embodiment of the present invention, the reaction in step (2) is carried out at a temperature of 30-50°C, for example 30°C, 40°C, or 50°C, preferably 30-40°C, for a time of 3-5 hours, for example 3 hours, 4 hours, or 5 hours, preferably 3-4 hours.
[0037] In a specific embodiment of the present invention, the alkaline aqueous solution in step (2) can be added to the system all at once, or it can be added in batches or continuously. It is preferred to use a drip feeding method. The feeding time of the alkaline aqueous solution is 2-3 hours, for example, 2.0 hours, 2.5 hours, or 3.0 hours.
[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0039] (1) This invention provides a two-component catalytic system with advantages such as high activity and almost no corrosion. It can greatly reduce the requirements for equipment materials. At the same time, the use of a tubular reactor for the ring-opening process of allyl glycidyl ether requires a residence time of only 0.5h-3h, which greatly shortens the reaction cycle.
[0040] (2) This invention uses an asymmetric Schiff base complex and a sterically hindered quaternary ammonium salt as a ring-opening catalyst for epoxides. The asymmetric structure of the Schiff base complex greatly enhances the selectivity of the ring-opening reaction, making it easier for the hydroxyl group to attack the sterically less hindered methylene carbon atom to generate product (A), while making it less likely to attack the methine carbon atom to generate byproduct (B). At the same time, the sterically hindered quaternary ammonium salt, in combination with it, further improves the reaction selectivity and greatly enhances the reaction efficiency. Therefore, this catalytic system has the characteristics of high selectivity and high activity, low byproduct selectivity, and a ring-opening reaction cycle of only 0.5-3 hours, which can greatly reduce the production cost of allyl glycidyl ether.
[0041] Attached Figure Description
[0042] Figure 1 The NMR spectrum of the ligand in Example 1 is shown. Detailed Implementation
[0043] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.
[0044] The main testing methods used in the embodiments and comparative examples of this invention are as follows:
[0045] Ring-opening selectivity: The content was determined by 1H-NMR at room temperature using a Bruker-400MHz MHz instrument with TMS as an internal standard.
[0046] The main raw materials used in the embodiments and comparative examples of this invention are as follows:
[0047] Ethylenediamine: Inokai reagent;
[0048] Epichlorohydrin: Inokai reagent;
[0049] 3,5-Di-tert-butylsalicylaldehyde: Inokai reagent;
[0050] 5-tert-butylsalicylaldehyde: Inokai reagent;
[0051] N,N-Dimethyladamantane ammonium chloride: Tianmen Hengchang Chemical Co., Ltd.;
[0052] Epichlorohydrin: Inokai reagent;
[0053] Example 1
[0054] The steps for preparing Schiff base complex A are as follows:
[0055] Take 3 g (0.05 mol, 60 g / mol) of ethylenediamine, 11.7 g (0.05 mol, 234 g / mol) of 3,5-di-tert-butylsalicylaldehyde, and 8.9 g (0.05 mol, 178 g / mol) of 5-tert-butylsalicylaldehyde, add them to a 250 mL single-necked flask, add 120 mL of anhydrous ethanol and stir. The reaction temperature is raised to 50 °C and the reaction is carried out for 8 h. After the reaction is completed, the reaction system is cooled in an ice-water bath, and a solid precipitates out. Filter and wash the filter cake with ice-cold ethanol, and dry the filter cake to obtain the Schiff base ligand.
[0056] The above ligand (5 g, 0.011 mol, 436 g / mol) was dissolved in 20 mL of dichloromethane, and SnCl4 (2.98 g, 0.011 mol, 260 g / mol) was added. The mixture was stirred at 30 °C for 5 h. The dichloromethane was then dried under vacuum, and the resulting solid was the desired Schiff alkali metal complex.
[0057] Example 2
[0058] The steps for preparing Schiff base complex B are as follows:
[0059] Take 3 g (0.05 mol, 60 g / mol) of ethylenediamine, 11.7 g (0.05 mol, 234 g / mol) of 3,5-di-tert-butylsalicylaldehyde, and 8.9 g (0.05 mol, 178 g / mol) of 5-tert-butylsalicylaldehyde, add them to a 250 mL single-necked flask, add 120 mL of anhydrous ethanol and stir. Heat the mixture to 50 °C and react for 8 h. After the reaction is complete, cool the reaction system in an ice-water bath. A large amount of solid will precipitate. Filter the mixture and wash the filter cake with ice-cold ethanol. Dry the filter cake to obtain the Schiff base ligand.
[0060] The above ligand (5 g, 0.011 mol, 436 g / mol) was dissolved in 20 mL of dichloromethane, and AlCl3 (1.46 g, 0.011 mol, 133 g / mol) was added. The mixture was stirred at 30 °C for 5 h. The dichloromethane was then dried under vacuum, and the resulting solid was the desired Schiff alkali metal complex.
[0061] Example 3
[0062] The preparation of the allyl chlorohydrin ether intermediate involves the following steps:
[0063] In a 1L three-necked flask, 750g of allyl alcohol, 0.375g of Schiff base complex A (554g / mol), and 0.146g of N,N-dimethyladamantane ammonium chloride (216g / mol) were added and completely purged with nitrogen. The mixture was heated to a reaction temperature of 50℃ to obtain raw material 1. Raw material 1 and 399g of epichlorohydrin were pumped uniformly and continuously into a tubular reactor at a molar ratio of 3:1. The reactor was subjected to a ring-opening reaction at 50℃ for 1 hour. The reaction solution was continuously collected to obtain the allyl chlorohydrin ether intermediate.
[0064] NMR results showed that the epichlorohydrin conversion rate was 99.5%, the allyl chlorohydrin ether intermediate accounted for 99.1%, and the allyl chlorohydrin ether isomer accounted for 0.9%.
[0065] 539 g of sodium hydroxide solution (32%) was added to the allyl chlorohydrin ether intermediate and stirred at 50 °C for 5 h to obtain crude allyl glycidyl ether. After desalting, it was distilled in a distillation column to obtain the finished product.
[0066] Example 4
[0067] The preparation of the allyl chlorohydrin ether intermediate involves the following steps:
[0068] In a 1L three-necked flask, 750g of allyl alcohol, 1.5g of Schiff base complex B (463g / mol), and 0.146g of N,N-dimethyladamantane ammonium chloride (216g / mol) were added and completely purged with nitrogen. The mixture was heated to a reaction temperature of 50℃ to obtain raw material 1. Raw material 1 and 399g of epichlorohydrin were then pumped uniformly and continuously into a tubular reactor at a molar ratio of 3:1. The reactor was subjected to a ring-opening reaction at 50℃ for 3 hours. The reaction solution was continuously collected to obtain the allyl chlorohydrin ether intermediate.
[0069] NMR results showed that the epichlorohydrin conversion rate was approximately 98.9%, the allyl chlorohydrin ether intermediate accounted for 98.5%, and the allyl chlorohydrin ether isomer accounted for 1.5%.
[0070] Example 5
[0071] The preparation of the allyl chlorohydrin ether intermediate involves the following steps:
[0072] 750 g of allyl alcohol and 0.375 g of Schiff base complex A (554 g / mol) were added to a 1 L three-necked flask, along with 0.146 g of N,N-dimethyladamantane ammonium chloride (216 g / mol). The mixture was thoroughly purged with nitrogen and heated to a reaction temperature of 30 °C. The above solution and 399 g of epichlorohydrin were then pumped uniformly and continuously into a tubular reactor at a molar ratio of 3:1. The reactor was subjected to a ring-opening reaction at 30 °C for 3 h. The reaction solution was continuously collected to obtain the allyl chlorohydrin ether intermediate.
[0073] NMR results showed that the epichlorohydrin conversion rate was approximately 95.3%, the allyl chlorohydrin ether intermediate accounted for 99.8%, and the allyl chlorohydrin ether isomer accounted for 0.2%.
[0074] Example 6
[0075] The preparation of the allyl chlorohydrin ether intermediate involves the following steps:
[0076] 750 g of allyl alcohol and 0.375 g of Schiff base complex A (554 g / mol) were added to a 1 L three-necked flask, along with 0.941 g of tetrabutylammonium chloride (278 g / mol). The mixture was fully purged with nitrogen and heated to a reaction temperature of 40 °C. The above solution and 399 g of epichlorohydrin were then pumped uniformly and continuously into a tubular reactor at a molar ratio of 3:1. The reactor was subjected to a ring-opening reaction at 40 °C for a residence time of 0.5 h. The reaction solution was continuously collected to obtain the allyl chlorohydrin ether intermediate.
[0077] NMR results showed that the epichlorohydrin conversion rate was approximately 94.6%, the allyl chlorohydrin ether intermediate accounted for 99.2%, and the allyl chlorohydrin ether isomer accounted for 0.8%.
[0078] Comparative Example 1
[0079] The allyl chlorohydrin ether intermediate was prepared according to the method in Example 4, except that the catalytic system was replaced with tin tetrachloride, while other operations and conditions remained unchanged, and the allyl chlorohydrin ether product was obtained. Samples were taken for NMR testing.
[0080] NMR results showed that the epichlorohydrin conversion rate was approximately 33%, allyl chlorohydrin ether intermediate accounted for 93.7%, and allyl chlorohydrin ether isomer accounted for 6.3%.
[0081] Comparative Example 2
[0082] The allyl chlorohydrin ether intermediate was prepared according to the method in Example 4, except that N,N-dimethyladamantane ammonium chloride was not added, while other operations and conditions remained unchanged, and the allyl chlorohydrin ether product was obtained. Samples were taken for NMR testing.
[0083] NMR results showed that the epichlorohydrin conversion rate was approximately 73%, the allyl chlorohydrin ether intermediate accounted for 94.8%, and the allyl chlorohydrin ether isomer accounted for 5.2%.
[0084] Comparative Example 3
[0085] The allyl chlorohydrin ether intermediate was prepared according to the method in Example 4, except that no Schiff base complex catalyst was added, while other operations and conditions remained unchanged, and the allyl chlorohydrin ether product was obtained. Samples were taken for NMR testing.
[0086] NMR results showed that the epichlorohydrin conversion rate was approximately 13%, the allyl chlorohydrin ether intermediate accounted for 92.1%, and the allyl chlorohydrin ether isomer accounted for 7.9%.
[0087] Comparative Example 4
[0088] The allyl chlorohydrin ether intermediate was prepared according to the method in Example 4, except that the Schiff base complex catalyst was replaced with a metal complex with 3,5-di-tert-butylsalicylaldehyde on both sides of the skeleton. Other operations and conditions remained unchanged, and the allyl chlorohydrin ether intermediate was obtained. A sample was taken for NMR testing.
[0089] NMR results showed that the epichlorohydrin conversion rate was approximately 98.5%, the allyl chlorohydrin ether intermediate accounted for 96.5%, and the allyl chlorohydrin ether isomer accounted for 3.5%.
[0090] Comparative Example 5
[0091] The allyl chlorohydrin ether intermediate was prepared according to the method in Example 4, except that the Schiff base complex catalyst was replaced with a metal complex with 5-tert-butylsalicylaldehyde on both sides of the skeleton, while other operations and conditions remained unchanged, and the allyl chlorohydrin ether intermediate was obtained. A sample was then taken for NMR testing.
[0092] NMR results showed that the epichlorohydrin conversion rate was approximately 96.8%, the allyl chlorohydrin ether intermediate accounted for 95.2%, and the allyl chlorohydrin ether isomer accounted for 4.8%.
Claims
1. A method for preparing an allyl glycidyl ether, comprising the following steps: (1) A catalytic system consisting of Schiff base catalyst and phase transfer catalyst is added to allyl alcohol to obtain raw material 1; raw material 1 and epichlorohydrin are continuously fed into a tubular reactor, and the molar ratio of the two is 3-5:
1. The reactor is subjected to ring-opening reaction at 30-50℃, and the residence time is 0.5-3h. The reaction liquid is continuously collected to obtain allyl chlorohydrin ether intermediate. (2) Add an aqueous solution of sodium hydroxide to the allyl chlorohydrin intermediate collected in step (1), wherein the molar ratio of sodium hydroxide to epichlorohydrin is 0.9-1.1:1, the ring-closing reaction time is 3-5 h, and the reaction temperature is 30-50 °C, to obtain the crude product of allyl glycidyl ether. (3) After desalting the crude product in step (2), it is distilled in a distillation column to obtain the finished product; The Schiff base catalyst comprises an ethylenediamine framework and an asymmetric salicylaldehyde structure, and one or more of Sn, Al, and Fe central atoms.
2. The method according to claim 1, characterized in that, The structural formula of the Schiff base catalyst is shown below. Where M represents Sn, Al, or Fe.
3. The method according to claim 1 or 2, characterized in that, The preparation method of the Schiff base catalyst includes the following steps: 1) Dissolve ethylenediamine, 3,5-di-tert-butylsalicylaldehyde and 5-tert-butylsalicylaldehyde in an organic solvent, stir, and react. Cool the reaction system in an ice-water bath. A large amount of solid will precipitate out. Filter and wash the filter cake with ice-cold ethanol. Dry the filter cake to obtain Schiff base ligands. 2) Dissolve the above ligand in dichloromethane, add the metal salt, stir, remove the dichloromethane, and the resulting solid is the Schiff base metal complex.
4. The method according to claim 3, characterized in that, The 3,5-di-tert-butylsalicylaldehyde or 5-tert-butylsalicylaldehyde is 1-1.1 times the molar amount of ethylenediamine.
5. The method according to claim 3, characterized in that, In step 2), the metal salt is one or more of SnCl4, AlCl3, and FeCl3.
6. The method according to claim 1, characterized in that, The phase transfer catalyst is selected from one or more of N,N-dimethyl-1-adamantaneamine, triethylbenzylammonium chloride, tetrabutylammonium chloride, and tetramethylammonium chloride.
7. The method according to claim 1, characterized in that, In step (1), the amount of Schiff base catalyst added is 0.05-0.2% of the mass of allyl alcohol.
8. The method according to claim 1, characterized in that, In step (1), the amount of Schiff base catalyst added is 0.08-0.1% of the mass of allyl alcohol.
9. The method according to claim 1, characterized in that, In step (1), the molar ratio of Schiff base catalyst and phase transfer catalyst is 1:1-5.