Method for synthesizing 2-methylsuccinic acid from itaconic acid
By using a modified Pd/C catalyst and ammonia-treated carbon support in the autoclave, catalytic hydrogenation reaction was solved in the prior art, and the low selectivity and conversion rate, large catalyst usage, and flammable and explosive solvents were solved. The problem of this problem is that efficient and simple synthesis of 2-methylsuccinic acid is achieved, and the product purity and yield are both high.
Patent Information
- Application Number
- CN202411624925.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-02-18
AI Technical Summary
The existing methods for synthesizing 2-methylsuccinic acid using itaconic acid as raw material have problems such as low selectivity and conversion rate, large catalyst usage and the need to use flammable and explosive solvents.
Solvent and itaconic acid were added to the autoclave, and a modified Pd/C catalyst was used to treat the modified carbon support by ammonia, and the reaction temperature and hydrogen pressure were controlled to carry out catalytic hydrogenation reaction.
The synthesis of 2-methylsuccinic acid with high selectivity and high conversion rate was achieved, reducing the loss and use of catalysts, and avoiding the occurrence of side reactions between alcohol and acids. The product purity is ≥99.7%, and the yield is ≥98%.
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of fine chemicals, and particularly relates to a method for synthesizing 2-methylsuccinic acid from itaconic acid. Background Art
[0002] 2-Methylsuccinic acid is also known as methylsuccinic acid. 2-Methylsuccinic acid and its derivatives can be used as catalysts for olefin polymerization, light stabilizers for polymers, ultraviolet absorbers and oilfield additives, waste paper bleaching, etching agents, esterification reactions and photochemical reactions, etc. They are widely used in pesticides, medicines, petrochemicals, etc.
[0003] The synthesis methods of methylsuccinic acid include oxidation, ester hydrolysis, and catalytic hydrogenation. The oxidation method requires high temperature and pressure, is time-consuming, and has low yields; the ester hydrolysis method has a complex process, many operating steps, high costs, and uses highly toxic substances. These two methods have gradually been replaced by catalytic hydrogenation.
[0004] Tao Hongjun used itaconic acid as raw material and Ni / SiO2 as catalyst to synthesize methylsuccinic acid by fixed-bed continuous catalytic hydrogenation. The reaction conversion rate was 80.6% and the selectivity was only 88.1%. Both the selectivity and conversion rate were not high.
[0005] Shi Huancong and others from Fudan University used itaconic acid as raw material and liquid phase hydrogenation to synthesize methylsuccinic acid, Pd / C as catalyst, the ratio of catalyst to itaconic acid was 0.025-1.5, the volume ratio of ethanol to tetrahydrofuran was 0-4, the reaction temperature was 10-80°C, the reaction pressure was 0.1-10MPa, and the reaction time was 2-16h; then recrystallization was performed with ether as solvent to obtain methylsuccinic acid with a content of 99%, and the conversion rate and selectivity were >99%. However, the problem is that the amount of catalyst used is very large, reaching 2.5%-150% of the raw material; ethanol and tetrahydrofuran are used as solvents, and the acid and alcohol generate esterification impurities, which requires the use of ether, a flammable and explosive solvent, for recrystallization. 2-Methylsuccinic acid has strong acidity and is easy to generate esterification impurities with alcohol solvents. The raw material itaconic acid has double bonds and carbonyl conjugation, and has strong chemical activity, which is easy to produce self-polymerization reaction. The self-polymer blocks the pores, causing the activity and stability of the Pd / C catalyst to decrease, resulting in poor hydrogenation selectivity and low hydrogenation liquid content. Subsequent recrystallization treatment is required to obtain the product.
[0006] Therefore, it is necessary to design a new synthesis method for synthesizing 2-methylsuccinic acid. Summary of the invention
[0007] The purpose of the present invention is to provide a method for synthesizing 2-methylsuccinic acid from itaconic acid, so as to solve the problems that the existing method for synthesizing 2-methylsuccinic acid using itaconic acid as a raw material proposed in the background technology either has low selectivity and conversion rate, or has a very large amount of catalyst and requires the use of flammable and explosive solvents for recrystallization.
[0008] To achieve the above object, the present invention provides a method for synthesizing 2-methylsuccinic acid from itaconic acid, comprising the following steps:
[0009] A solvent and itaconic acid are added to a high-pressure reactor, and a modified Pd / C catalyst is used. The carbon carrier used for the modified Pd / C catalyst is a carbon carrier modified by ammonia treatment. After nitrogen replacement, hydrogen is introduced, the temperature is controlled at 80-100° C., the hydrogen pressure is controlled at 2-4 MPa, and the temperature and pressure are maintained until no raw material remains after hydrogen is not absorbed; after the reaction is completed, the reaction is filtered, and the modified Pd / C catalyst is applied; the filtrate is evaporated to dryness to obtain 2-methylsuccinic acid.
[0010] In a specific embodiment, the solvent is pure water.
[0011] In a specific embodiment, the weight ratio of the solvent and itaconic acid added to the autoclave is 3-6:1.
[0012] In a specific embodiment, the modified Pd / C catalyst is added in an amount of 0.5-1.5% of itaconic acid.
[0013] In a specific embodiment, the ammonia modification treatment steps of the carbon carrier used for the modified Pd / C catalyst are as follows: take activated carbon powder, place it in the constant temperature zone of a tubular furnace, replace it with nitrogen, heat it to 800°C, pass ammonia, replace it with nitrogen after the ammonia passing, and cool it to room temperature.
[0014] In a specific embodiment, the ammonia flow rate is 50 mL / min and the time is 60 min.
[0015] In a specific embodiment, the preparation method of the modified Pd / C catalyst is as follows: purified water is used as the base, an activated carbon carrier is added, and the temperature is raised to 80°C and kept warm for 0.5-1h; chloropalladic acid solution is added dropwise, and after the addition is completed, the mixture is kept warm at 80°C and stirred for 3-4h. After the insulation is completed, NaOH solution is added dropwise at 80°C, the pH value of the solution is adjusted to 10, and the mixture is kept warm for 2-3h after the addition is completed;
[0016] Add the formaldehyde solution drop by drop; keep warm at 80°C for 1-2h after the addition is completed; filter and wash the filter cake to obtain a modified Pd / C catalyst.
[0017] In a specific embodiment, the NaOH solution is a NaOH solution with a mass concentration of 10%, and the formaldehyde solution is a formaldehyde solution with a mass concentration of 36%.
[0018] In a specific embodiment, the filter cake is washed by washing the filter cake with hot purified water until the filtrate is free of chloride ions, and AgNO3 is used to detect the absence of chloride ions.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] The invention has the advantages of being able to use itaconic acid as a raw material and to synthesize 2-methylsuccinic acid with high selectivity and simplicity.
[0021] The modified Pd / C catalyst in the present invention can be repeatedly recovered and reused after use, and can be reused at least 9 times, and the amount of modified Pd / C catalyst added in each batch is less than 5% of the amount of modified Pd / C catalyst added for the first time, indicating that the loss of catalyst in the catalytic process is very small.
[0022] The reaction of the present invention uses water as solvent, and compared with alcohol solvents, the occurrence of alcohol and acid side reactions is avoided.
[0023] The activated carbon in the present invention is modified by ammonia, so that the acidic functional group content on the surface of the activated carbon is reduced, the self-polymerization problem of itaconic acid is avoided, the stability and activity of the catalyst are improved, the amount of catalyst is reduced, and the hydrogenation liquid content is increased to improve the selectivity.
[0024] The hydrogenation liquid in the present invention does not need to be purified, and the product can be obtained by evaporating the solvent to dryness. The product purity is ≥99.7% and the yield is ≥98%.
[0025] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention is further described in detail below. DETAILED DESCRIPTION
[0026] The embodiments of the present invention are described in detail below. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0027] The present invention uses activated carbon treated with ammonia as a carrier to prepare a Pd / C catalyst.
[0028] Modification of carbon carrier: Take 10-15g of activated carbon powder, place it in the constant temperature zone of a tubular furnace, replace it with nitrogen twice, raise the temperature to 800℃, pass ammonia, the ammonia flow rate is 50mL / min, the time is 60min, replace it with nitrogen twice after passing ammonia, and cool it to room temperature.
[0029] Preparation of 5% Pd / C catalyst: 100.0g purified water was used as the base, 10g activated carbon carrier was added, and the temperature was raised to 80℃ and kept warm for 0.5-1h. 10.52g chloropalladic acid solution (H2PdCl4, 0.05gPd / g) was added dropwise, and after the addition was completed, the temperature was kept at 80℃ and stirred for 3-4h. After the temperature was kept warm, 10% NaOH solution was added dropwise at 80℃ to adjust the pH value of the solution to 10. After the addition was completed, the temperature was kept warm for 2-3h.
[0030] 1.80 g of 36% formaldehyde solution was added dropwise. After the addition was completed, the temperature was kept at 80°C for 1-2 hours. Filter and wash the filter cake with hot purified water until the filtrate was free of chloride ions: AgNO3 was used to detect the absence of chloride ions. The catalyst-modified Pd / C catalyst was obtained, packaged, and used for hydrogenation after the water content was measured.
[0031] Example 1
[0032] 300g of water, 100g of itaconic acid, and 3.15g of modified Pd / C as a catalyst (containing 52.5% water) were added to the autoclave. After nitrogen replacement, hydrogen was introduced at a temperature of 80-90°C and a hydrogen pressure of 2-4MPa. After hydrogen absorption stopped, the temperature and pressure were maintained until no raw material remained. The hydrogen absorption time was 3.5h. After the reaction was completed, the reaction was filtered and the filtrate was evaporated to dryness to obtain 99.5g of the product with a purity of 99.89%, which was detected by high performance liquid chromatography (HPLC).
[0033] Example 2
[0034] Add 300g of water, 100g of itaconic acid, and 2.11g of modified Pd / C as catalyst (containing 52.5% water) into the autoclave. After nitrogen replacement, introduce hydrogen, control the temperature at 90-100°C, and the hydrogen pressure at 2-4MPa. Keep the temperature and pressure until no raw material remains after hydrogen absorption stops. The hydrogen absorption time is 4h. After the reaction is completed, filter and evaporate the filtrate to obtain 99.9g of product with a product purity of 99.85%.
[0035] Example 3
[0036] Add 600g of water, 100g of itaconic acid, and 2.11g of modified Pd / C as catalyst (containing 52.5% water) into the autoclave. After nitrogen replacement, introduce hydrogen, control the temperature at 90-100°C, and the hydrogen pressure at 2-4MPa. Keep the temperature and pressure until no raw material remains after hydrogen absorption stops. The hydrogen absorption time is 5h. After the reaction is completed, filter and evaporate the filtrate to obtain 99.7g of product with a product purity of 99.73%.
[0037] Example 4
[0038] Add 300g of water, 100g of itaconic acid, and 1.05g of modified Pd / C as catalyst (containing 52.5% water) into the autoclave. After nitrogen replacement, introduce hydrogen, control the temperature at 80-90°C, and the hydrogen pressure at 2-4MPa. Keep the temperature and pressure until no raw material remains after hydrogen absorption. The hydrogen absorption time is 7.5h. After the reaction is completed, filter and evaporate the filtrate to obtain 99.9g of product with a product purity of 99.88%. Filter out the solid to recover the catalyst and apply it to the next batch of reactions. When applying, add 0.05g of new catalyst for each batch.
[0039] The following table shows the catalyst times and product purity:
[0040] first 1 2 3 4 5 6 7 8 9 purity% 99.88 99.84 99.89 99.78 99.89 99.79 99.76 99.81 99.80 99.85 Hydrogenation time 7.5 7.5 7.2 7.2 7 7.3 7.2 7 7 7.2
[0041] The modified Pd / C in Examples 1 to 4 are all 5% Pd / C catalysts.
[0042] Comparative Example 1
[0043] Add 300g of water, 100g of itaconic acid, and 1.18g of Pd / C as a catalyst (containing 57.8% water) into the autoclave. After nitrogen replacement, introduce hydrogen, control the temperature at 80-90°C, and the hydrogen pressure at 2-4MPa. After hydrogen absorption stops, keep the temperature and pressure until no raw material remains. The hydrogen absorption time is 21h. After the reaction is completed, filter and evaporate the filtrate to obtain 99.5g of the product with a product purity of 99.13%.
[0044] The invention has the advantages of being able to use itaconic acid as a raw material and to synthesize 2-methylsuccinic acid with high selectivity and simplicity.
[0045] The modified Pd / C catalyst in the present invention can be repeatedly recovered and reused after use, and can be reused at least 9 times, and the amount of modified Pd / C catalyst added in each batch is less than 5% of the amount of modified Pd / C catalyst added for the first time, indicating that the loss of catalyst in the catalytic process is very small.
[0046] The reaction of the present invention uses water as solvent, and compared with alcohol solvents, the occurrence of alcohol and acid side reactions is avoided.
[0047] The activated carbon in the present invention is modified by ammonia, so that the acidic functional group content on the surface of the activated carbon is reduced, the self-polymerization problem of itaconic acid is avoided, the stability and activity of the catalyst are improved, the amount of catalyst is reduced, and the hydrogenation liquid content is increased to improve the selectivity.
[0048] The hydrogenation liquid in the present invention does not need to be purified, and the product can be obtained by evaporating the solvent to dryness. The product purity is ≥99.7% and the yield is ≥98%.
[0049] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions and substitutions can be made without departing from the concept of the present invention, which should be regarded as belonging to the protection scope of the present invention.
Claims
1. A method for synthesizing 2-methylsuccinic acid from itaconic acid, characterized in that: The steps include: A solvent and itaconic acid are added to a high-pressure reactor, and a modified Pd / C catalyst is used. The carbon carrier used for the modified Pd / C catalyst is a carbon carrier modified by ammonia treatment. After nitrogen replacement, hydrogen is introduced, the temperature is controlled at 80-100° C., the hydrogen pressure is controlled at 2-4 MPa, and the temperature and pressure are maintained until no raw material remains after hydrogen is not absorbed; after the reaction is completed, the reaction is filtered, and the modified Pd / C catalyst is applied; the filtrate is evaporated to dryness to obtain 2-methylsuccinic acid.
2. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 1, characterized in that: The solvent is pure water.
3. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 2, characterized in that: The weight ratio of the solvent and itaconic acid added into the high-pressure reactor is 3-6:
1.
4. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 1, characterized in that: The added amount of the modified Pd / C catalyst is 0.5-1.5% of itaconic acid.
5. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 1, characterized in that: The ammonia modification treatment steps of the carbon carrier used for the modified Pd / C catalyst are as follows: taking activated carbon powder, placing it in the constant temperature zone of a tubular furnace, replacing it with nitrogen, heating it to 800° C., passing ammonia, replacing it with nitrogen after passing ammonia, and cooling it to room temperature.
6. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 5, characterized in that: The ammonia flow rate was 50 mL / min and the time was 60 min.
7. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 1, characterized in that: The preparation method of the modified Pd / C catalyst is as follows: purified water is used as the base, an activated carbon carrier is added, and the temperature is raised to 80° C. and kept warm for 0.5-1h; a chloropalladic acid solution is added dropwise, and after the addition is completed, the mixture is kept warm at 80° C. and stirred for 3-4h; after the insulation is completed, a NaOH solution is added dropwise at 80° C., the pH value of the solution is adjusted to 10, and after the addition is completed, the mixture is kept warm for 2-3h; Add the formaldehyde solution drop by drop; keep warm at 80°C for 1-2h after the addition is completed; filter and wash the filter cake to obtain a modified Pd / C catalyst.
8. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 7, characterized in that: The NaOH solution is a NaOH solution with a mass concentration of 10%, and the formaldehyde solution is a formaldehyde solution with a mass concentration of 36%.
9. The method for synthesizing 2-methylsuccinic acid from itaconic acid according to claim 7, characterized in that: The filter cake is washed with hot purified water until the filtrate is free of chloride ions, and AgNO3 is used to detect the absence of chloride ions.