A metal catalyst and a preparation method thereof, and a preparation method of 2,3,5-trimethylhydroquinone diester
By using a metal catalyst to react with air to generate 2,3,5-trimethylhydroquinone diester, the problems of high production cost and equipment corrosion in the prior art have been solved, and the preparation of 2,3,5-trimethylhydroquinone diester with high purity and high yield has been achieved.
Patent Information
- Application Number
- CN202410058266.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-15
- Publication Date
- 2026-08-25
- Estimated Expiration
- 2044-01-15
AI Technical Summary
Existing technologies for preparing 2,3,5-trimethylhydroquinone diester suffer from high production costs, significant equipment corrosion risks, and low product yields. In particular, the use of strong acid catalysts leads to high costs for industrial waste treatment and high investment in equipment corrosion prevention.
A metal catalyst was used instead of a conventional acid catalyst, and inexpensive air was used as the oxide source. The metal catalyst reacted with pseudotrimethylbenzene to produce 2,3,5-trimethylhydroquinone diester, and the crude product was purified by continuous distillation to obtain a high-purity, high-yield product.
It achieves mild reaction conditions, low production costs, and high product yield, avoids material corrosion problems caused by acidic catalysts, simplifies the separation process, and improves product purity and yield.
Smart Images
Figure QLYQS_1 
Figure QLYQS_2 
Figure BDA0004665492520000011
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a metal catalyst and its preparation method, and a method for preparing 2,3,5-trimethylhydroquinone diester. Background Technology
[0002] Vitamin E is widely used in food, medicine, and cosmetics due to its anti-aging and immune-boosting effects in the human body. 2,3,5-Trimethylhydroquinone diester is an important intermediate in the synthesis of vitamin E, and optimizing its preparation process is crucial for the development of the vitamin E industry. Traditional preparation processes mainly include the tricresyl process, the pseudotrimethylbenzene process, and the isophorone process.
[0003] The trimethylphenol process uses trimethylphenol as a raw material and a strong base as a catalyst, followed by a high-temperature and high-pressure reaction. However, this route uses expensive 2,4,6-trimethylphenol, resulting in high production costs and making industrial-scale production difficult.
[0004]
[0005] The pseudotrimethylbenzene process uses propylene as an alkylating agent, followed by sulfonation, alkali fusion, and dealkylation to synthesize TMHQ. This method is mild but has a long route, poor reaction selectivity, and is difficult to purify and separate.
[0006]
[0007] The isophorone process uses acetone as a starting material, and proceeds through polymerization, isomerization, oxidation, and rearrangement to obtain trimethylhydroquinone diester. This method has a complex synthetic route, uses strong acids as catalysts, poses a significant risk of equipment corrosion, and results in high costs for industrial production.
[0008]
[0009] Patent CN1241559A reports a process using oxoisophorone as a raw material and strong acids such as perchloric acid, sulfuric acid, or fluorosulfonic acid as catalysts. Although the process route is simple, the raw material cost is high, and the strong acids used in the catalysis will generate a large amount of wastewater. The industrial waste treatment cost and equipment corrosion prevention investment are also high.
[0010] Patent CN1273963A reports a process using oxoisophorone as a raw material, followed by separation and purification through crystallization and secondary reaction of the crystallization filtrate, but the yield of the obtained product is only 88%.
[0011] Developing a new method for preparing 2,3,5-trimethylhydroquinone diester with mild reaction conditions, low production cost, and high yield is of great significance. Summary of the Invention
[0012] The purpose of this invention is to provide a novel metal catalyst and its preparation method, as well as a method for preparing 2,3,5-trimethylhydroquinone diester. This method uses a metal catalyst instead of a conventional acidic catalyst in the preparation process, employs inexpensive air as the oxide source, has a simple reaction route, high product yield, and avoids the material corrosion problems caused by acidic catalysts.
[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0014] In a first aspect, the present invention provides a metal catalyst having the following structure:
[0015]
[0016] A second aspect of the present invention provides a method for preparing a metal catalyst, wherein the metal catalyst is prepared by reacting N1,N2-dimethyl-1,2-dinaphthylamine as a ligand with a copper salt under alkaline conditions.
[0017] Preferably, the metal catalyst is prepared by the following method:
[0018] (1) Dissolve the ligand N1,N2-dimethyl-1,2-dinaphthylamine and the base in an organic solvent;
[0019] (2) In an inert atmosphere, copper salt is added to the above ligand solution to react, filtered and washed with an organic solvent to obtain the metal catalyst.
[0020] Preferably, the structural formula of the ligand N1,N2-dimethyl-1,2-dinaphthylamine is as follows:
[0021]
[0022] Preferably, the alkali in step 1) is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate, with potassium carbonate being preferred; the mass ratio of the alkali to the ligand is 1:50-200, with 1:80-130 being preferred.
[0023] Preferably, the organic solvent in step 1) is one or more of methanol, ethanol, ethylene glycol, and benzyl alcohol, with ethylene glycol being preferred; the mass ratio of the organic solvent to the ligand is 1:0.02-0.1, preferably 1:0.05-0.08;
[0024] Preferably, the copper salt in step 2) is one or more of copper acetate, copper chloride, and copper sulfate, with copper chloride being the most preferred; the mass ratio of the copper salt to the ligand is 1:5-25, more preferably 1:10-15; and the reaction temperature is 80-250℃, more preferably 150-210℃.
[0025] A third aspect of the present invention provides a method for preparing 2,3,5-trimethylhydroquinone diester, using parabens as a raw material, air as an oxidizing agent, and acetic anhydride as an acetylation reagent, and reacting under the action of the metal catalyst described in the present invention to generate 2,3,5-trimethylhydroquinone diester.
[0026] Preferably, the mass ratio of the added acetic anhydride to the added p-trimethylbenzene is 1:1.5-5, more preferably 1:2-4;
[0027] Preferably, the mass ratio of the metal catalyst to pseudotrimethylbenzene is 1:50-200, more preferably 1:80-120;
[0028] Preferably, the pressure of the air after it is introduced is 0.1-0.5 mPa, and the flow rate is 2-10 L / min, more preferably 0.15-0.3 mPa and 5-8 L / min;
[0029] Preferably, the reaction temperature is 80-150℃, more preferably 100-120℃;
[0030] Preferably, the preparation method includes the following steps: mixing and dissolving pseudotrimethylbenzene and a solvent, and preheating by heating;
[0031] Then a metal catalyst is added, and air is introduced to carry out the reaction, yielding 2,3,5-trimethylhydroquinone diester;
[0032] Preferably, the preheating temperature is 30-60℃, more preferably 40-50℃.
[0033] After the reaction is complete, the catalyst is filtered out, and the solvent is removed by vacuum distillation to obtain crude trimethylhydroquinone diester.
[0034] The vacuum distillation temperature is 80-150℃, and the vacuum degree is 20-80kPa, preferably 100-120℃ and 30-60kPa.
[0035] Preferably, high-purity 2,3,5-trimethylhydroquinone diester can be obtained by continuous distillation of the crude 2,3,5-trimethylhydroquinone diester.
[0036] Preferably, the continuous distillation includes the following steps:
[0037] a) Add the bottom liquid to the distillation column to reduce the vacuum in the distillation column. After the temperature of the column bottom rises to 75-120℃, preferably 90-110℃, start continuously adding the crude 2,3,5-trimethylhydroquinone diester to the column bottom of the distillation column.
[0038] b) 2,3,5-trimethylhydroquinone diester is purified by distillation under a vacuum of 0.05-0.4 kPa, preferably 0.1-0.2 kPa, and a temperature of 100-300℃, preferably 150-250℃.
[0039] Preferably, the base coat liquid in step a) is one or more of p-trimethylbenzene and acetic anhydride, with acetic anhydride being preferred;
[0040] Preferably, in step a), the mass ratio of the base solution to the crude 2,3,5-trimethylhydroquinone diester is 1:1.5-5, more preferably 1:2-3;
[0041] Preferably, the feed temperature of 2,3,5-trimethylhydroquinone diester in step a) is 100-200°C, more preferably 150-180°C;
[0042] Preferably, in step a), the vacuum level is reduced to 50-90 kPa, more preferably 60-80 kPa;
[0043] Preferably, the feed rate of crude 2,3,5-trimethylhydroquinone diester in step a) is 5-100 g / min, more preferably 20-80 g / min;
[0044] The vapor at the top of the distillation column is condensed and refluxed, with part of the reflux liquid flowing back into the distillation column and the rest collected in the product vessel;
[0045] Preferably, the reflux ratio of the distillation column is controlled at 1:0.05-0.2, more preferably 1:0.1-0.15.
[0046] The beneficial effects of this invention are as follows:
[0047] Using parabens as a raw material, and with the action of a metal catalyst, air is continuously introduced into the reaction system as an oxidant to prepare a product with a selectivity >95% for 2,3,5-trimethylhydroquinone diester. The use of inexpensive air as the source of oxides results in a simple reaction route, high product yield, and avoids the material corrosion problem caused by acidic catalysts.
[0048] Purifying crude 2,3,5-trimethylhydroquinone diester via continuous distillation yields a high-purity, high-yield product. The separation process is simple and avoids the product waste in the filtrate that occurs in traditional crystallization processes. Detailed Implementation
[0049] The technical solution of the present invention will be further described below through specific embodiments, but it is not limited thereto.
[0050] N1,N2-Dimethyl-1,2-dinaphthylamine: CAS 1309366-57-1, Shanghai Bide Pharmaceutical Co., Ltd.
[0051] NMR testing conditions: Weigh 0.05g of metal catalyst and dissolve it in 5ml of deuterated chloroform. The sample was tested using a Jeol-ECZ400S NMR instrument.
[0052] Example 1
[0053] The metal catalyst is prepared as follows:
[0054] 50 g of N1,N2-dimethyl-1,2-dinaphthylamine and 0.50 g of sodium carbonate were weighed into 1000 g of ethylene glycol solvent. The solvent was purged with nitrogen, and then 4.2 g of copper chloride was added. The mixture was heated to 200 °C and refluxed for 3 h. The mixture was then filtered and washed with ethylene glycol to obtain 50 g of the resulting metal catalyst. NMR analysis showed the following results: 13 C NMR (101MHz, Chloroform-d) δ137.5,130.6,128.6,125.8,125.6,122.9,78,75.5,66,44.4,31ppm.
[0055] Preparation and separation process of 2,3,5-trimethylhydroquinone diester:
[0056] Weigh 300g of pseudotrimethylbenzene into a reaction vessel, then add 150g of acetic anhydride to mix and dissolve. Preheat the mixture to 45℃, then add 3g of metal catalyst into the reaction vessel. Then, introduce air at 0.3mPa at a flow rate of 5L / min to carry out the reaction. Continue to heat the mixture to 100℃ to carry out the reaction. The reaction ends when the conversion rate of pseudotrimethylbenzene is ≥99%. Filter out the catalyst, and remove the solvent by vacuum distillation at 100℃ and 50kPa to obtain crude 2,3,5-trimethylhydroquinone diester.
[0057] The crude 2,3,5-trimethylhydroquinone diester prepared above was heated to 150°C for feeding. 250 g of pseudotrimethylbenzene was added to the reboiler of a distillation column, and the temperature was raised to 90°C. The pressure was then reduced to 70 kPa, and the distillation column was preheated to 90°C. The crude trimethylhydroquinone diester, heated to 150°C, was then added to the reboiler of the distillation column at a rate of 20 g / min. The vacuum was further reduced to 0.2 kPa, and the reboiler temperature was raised to 180°C. After the reflux stabilized, the reflux ratio was adjusted to 1:0.1 for collection. The collected components were analyzed; the purity of 2,3,5-trimethylhydroquinone diester was 99.8%, and the product yield, calculated based on pseudotrimethylbenzene, was 95.6%.
[0058] Example 2
[0059] The metal catalyst is prepared as follows:
[0060] 50g of N1,N2-dimethyl-1,2-dinaphthylamine and 0.63g of potassium carbonate were weighed into 835g of methanol solvent and purged with nitrogen. Then, 3.3g of copper acetate was added to the solvent, and the mixture was heated to 150℃ and refluxed for 5h. The mixture was then filtered and washed with methanol to separate 46g of the obtained metal catalyst.
[0061] Preparation and separation process of 2,3,5-trimethylhydroquinone diester:
[0062] Weigh 250g of pseudotrimethylbenzene into a reaction vessel, then add 61g of acetic anhydride to mix and dissolve. Preheat the mixture to 55℃, then add 2.5g of metal catalyst into the reaction vessel. Then, introduce air at 0.2mPa at a flow rate of 7L / min to carry out the reaction. Continue to heat the mixture to 120℃ to carry out the reaction. The reaction ends when the conversion rate of pseudotrimethylbenzene is ≥99%. Filter out the catalyst, and remove the solvent by vacuum distillation at 120℃ and 60kPa to obtain crude 2,3,5-trimethylhydroquinone diester.
[0063] The crude 2,3,5-trimethylhydroquinone diester prepared above was heated to 190°C for feeding. 200g of acetic anhydride was added to the distillation column reboiler, and the temperature was raised to 100°C. The pressure was then reduced to 80kPa to preheat the distillation column. The heated crude 2,3,5-trimethylhydroquinone diester was then added to the distillation column reboiler at a rate of 30g / min. The vacuum was further reduced to 0.15kPa, and the reboiler temperature was raised to 200°C. After the reflux stabilized, the reflux ratio was adjusted to 1:0.2 for collection. The collected components were analyzed; the purity of 2,3,5-trimethylhydroquinone diester was 99.9%, and the product yield, calculated based on pseudotrimethylbenzene, was 96.0%.
[0064] Example 3
[0065] The metal catalyst is prepared as follows:
[0066] 50g of N1,N2-dimethyl-1,2-dinaphthylamine and 0.33g of potassium bicarbonate were weighed into 500g of ethanol solvent and purged with nitrogen. Then, 2.0g of copper sulfate was added to the solvent, and the mixture was heated to 180℃ and refluxed for 3.5h. The mixture was then filtered and washed with ethanol to separate 43g of the obtained metal catalyst.
[0067] Weigh 250g of pseudotrimethylbenzene into a reaction vessel, then add 165g of acetic anhydride to mix and dissolve. Preheat the mixture to 40℃, then add 1.6g of metal catalyst into the reaction vessel. Then, introduce air at 0.2mPa at a flow rate of 10L / min to carry out the reaction. Continue to heat the mixture to 90℃ and carry out the reaction until the conversion rate of pseudotrimethylbenzene is ≥99%. Filter out the catalyst, and remove the solvent by vacuum distillation at 90℃ and 30kPa to obtain crude 2,3,5-trimethylhydroquinone diester.
[0068] The crude 2,3,5-trimethylhydroquinone diester prepared above was heated to 120°C for feeding. 100g of acetic anhydride was added to the reboiler of a distillation column, and the temperature was raised to 110°C. The pressure was then reduced to 80kPa to preheat the distillation column. The heated crude 2,3,5-trimethylhydroquinone diester was then added to the reboiler of the distillation column at a rate of 50g / min. The vacuum was further reduced to 0.1kPa, and the reboiler temperature was raised to 220°C. After the reflux stabilized, the reflux ratio was adjusted to 1:0.05 for collection. The collected components were analyzed; the purity of the 2,3,5-trimethylhydroquinone diester was 99.8%, and the product yield, calculated based on pseudotrimethylbenzene, was 97.1%.
[0069] Example 4
[0070] The metal catalyst is prepared as follows:
[0071] 50g of N1,N2-dimethyl-1,2-dinaphthylamine and 1g of sodium carbonate were weighed into 625g of benzyl alcohol solvent and purged with nitrogen. Then, 6.3g of copper acetate was added to the solvent, and the mixture was heated to 220℃ and refluxed for 6h. The mixture was then filtered and washed with benzyl alcohol to separate 45g of the obtained metal catalyst.
[0072] Weigh 200g of pseudotrimethylbenzene into a reaction vessel, then add 40g of acetic anhydride to mix and dissolve. Preheat the mixture to 60℃, then add 4g of metal catalyst into the reaction vessel. Then, introduce air at 0.3mPa at a flow rate of 6L / min to carry out the reaction. Continue to heat the mixture to 100℃ to carry out the reaction. The reaction ends when the conversion rate of pseudotrimethylbenzene is ≥99%. Filter out the catalyst, and remove the solvent by vacuum distillation at 90℃ and 60kPa to obtain crude 2,3,5-trimethylhydroquinone diester.
[0073] The crude 2,3,5-trimethylhydroquinone diester prepared above was heated to 100°C for feeding. 120 g of acetic anhydride was added to the reboiler of a distillation column, and the temperature was raised to 120°C. The pressure was then reduced to 60 kPa to preheat the distillation column. The heated crude 2,3,5-trimethylhydroquinone diester was then added to the reboiler of the distillation column at a rate of 60 g / min. The vacuum was further reduced to 0.05 kPa, and the reboiler temperature was raised to 200°C. After the reflux stabilized, the reflux ratio was adjusted to 1:0.1 for collection. The collected components were analyzed. The purity of the 2,3,5-trimethylhydroquinone diester was 99.9%, and the product yield, calculated based on pseudotrimethylbenzene, was 97.3%.
[0074] Comparative Example 1
[0075] 200g of pseudotrimethylbenzene was weighed into a reaction vessel, and then 40g of acetic anhydride was added to dissolve it. The mixture was heated to 60℃ for preheating, and then 4g of copper acetate was added as a catalyst into the reaction vessel. Air was then introduced at a flow rate of 6L / min at 0.3mPa to carry out the reaction. The temperature was further increased to 100℃ to carry out the reaction. After 20 hours of reaction, the conversion rate of pseudotrimethylbenzene was 17%. Analysis of the reaction solution showed no formation of 2,3,5-trimethylhydroquinone diester.
Claims
1. A method for preparing 2,3,5-trimethylhydroquinone diester, characterized in that, Using parabens as a raw material, air as an oxidant, and acetic anhydride as an acetylation reagent, 2,3,5-trimethylhydroquinone diester is produced under the action of a metal catalyst. The mass ratio of the added acetic anhydride to the added p-trimethylbenzene is 1:1.5-5; The mass ratio of the metal catalyst to pseudotrimethylbenzene is 1:50-200; The pressure of the air after it is introduced is 0.1-0.5 MPa, and the flow rate is 2-10 L / min; In the preparation of 2,3,5-trimethylhydroquinone diester, the reaction temperature is 80-150℃; The structure of the metal catalyst is as follows: 。 2. The preparation method according to claim 1, characterized in that, Metal catalysts were prepared by reacting N1,N2-dimethyl-1,2-dinaphthylamine as a ligand with copper salts under alkaline conditions.
3. The preparation method according to claim 2, characterized in that, The preparation method of the metal catalyst is as follows: (1) Add the ligand N1,N2-dimethyl-1,2-dinaphthylamine and the basic compound to an organic solvent; (2) In an inert atmosphere, copper salt is added to the above ligand solution to react, and the metal catalyst is obtained by filtration and washing. The alkaline compound mentioned in step 1) is one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, and sodium bicarbonate. The structural formula of the ligand N1,N2-dimethyl-1,2-dinaphthylamine is as follows: 。 4. The preparation method according to claim 3, characterized in that, The alkaline compound mentioned in step 1) is potassium carbonate.
5. The preparation method according to claim 3, characterized in that, The mass ratio of the basic compound to the ligand is 1:50-200.
6. The preparation method according to claim 5, characterized in that, The mass ratio of the basic compound to the ligand is 1:80-130.
7. The preparation method according to claim 3, characterized in that, The organic solvent mentioned in step 1) is one or more of methanol, ethanol, ethylene glycol, and benzyl alcohol.
8. The preparation method according to claim 7, characterized in that, The organic solvent mentioned in step 1) is ethylene glycol.
9. The preparation method according to claim 3, characterized in that, The mass ratio of the organic solvent to the ligand is 1:0.02-0.
1.
10. The preparation method according to claim 9, characterized in that, The mass ratio of the organic solvent to the ligand is 1:0.05-0.
08.
11. The preparation method according to claim 3, characterized in that, The copper salt mentioned in step 2) is one or more of copper acetate, copper chloride, and copper sulfate.
12. The preparation method according to claim 11, characterized in that, The copper salt mentioned in step 2) is copper chloride.
13. The preparation method according to claim 2, characterized in that, The mass ratio of the copper salt to the ligand is 1:5-25.
14. The preparation method according to claim 13, characterized in that, The mass ratio of the copper salt to the ligand is 1:10-15.
15. The preparation method according to claim 3, characterized in that, In the preparation method of the metal catalyst, the reaction temperature is 80-250℃.
16. The preparation method according to claim 15, characterized in that, In the preparation method of the metal catalyst, the reaction temperature is 150-210℃.
17. The preparation method according to claim 1, characterized in that, The mass ratio of the added acetic anhydride to the added pseudotrimethylbenzene is 1:2-4.
18. The preparation method according to claim 1, characterized in that, The mass ratio of the metal catalyst to pseudotrimethylbenzene is 1:80-120.
19. The preparation method according to claim 1, characterized in that, The pressure of the air after it is introduced is 0.15-0.3 MPa, and the flow rate is 5-8 L / min.
20. The preparation method according to claim 1, characterized in that, In the preparation of 2,3,5-trimethylhydroquinone diester, the reaction temperature is 100-120℃.
Citation Information
Patent Citations
Process for preparing 2,3,5-trimethyl hydroquinone di-esters
CN1273963A