Antioxidant TBHQ and preparation method thereof
By using reducing agent and nitrogen protection methods in the preparation process of antioxidant TBHQ, the generation of oxidation by-products is reduced, and the problem of unstable product quality in the prior art is solved, and TBHQ production with high purity and high yield is achieved.
Patent Information
- Application Number
- CN202410104656.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-25
- Publication Date
- 2025-07-25
AI Technical Summary
During the production process of existing antioxidant TBHQ, the production of oxidative by-products TBQ and DTBQ fluctuates greatly, affecting product quality and yield and increasing production costs.
In the preparation process of the antioxidant TBHQ, the dual measures of reducing agent and nitrogen protection are adopted to reduce the occurrence of oxidation side reactions and improve product purity and yield through steps such as alkylation reaction, azeotropic distillation and recrystallization.
Effectively reduce the generation of oxidative by-products TBQ and DTBQ, improve product quality and yield, reduce production costs, and extend product shelf life.
Smart Images
Figure CN120365152A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of antioxidant TBHQ, and in particular to an antioxidant TBHQ and a preparation method thereof. Background Art
[0002] Tert-butylhydroquinone, or antioxidant TBHQ for short, is a hindered phenol antioxidant with a wide range of applications and high cost-effectiveness, and has always attracted much attention in the chemical industry. TBHQ is more effective for unsaturated oils than other commonly used antioxidants such as BHA, BHT, and PG. It has many advantages such as no odor or peculiar smell when added to any oil, good safety, high antioxidant performance, and excellent oil solubility. At the same time, it can effectively inhibit the growth of bacteria and molds, and has a good inhibitory effect on molds that are harmful to human health, such as Aspergillus flavus. The good antioxidant effect is precisely because TBHQ itself is more easily oxidized, which has become a problem of TBHQ's own anti-oxidation during production and storage.
[0003] At present, the production method of the antioxidant TBHQ is as follows: hydroquinone (HQ) is added to a solvent, and in the presence of an acidic catalyst, it is subjected to an alkylation reaction with isobutylene (process 1) to generate a main product TBHQ and a by-product DTBHQ (2,5-di-tert-butylhydroquinone); after the reaction is completed, the reaction is separated by heat preservation and stratification (process 2), and the acid phase catalyst is separated and used as a catalyst for the next batch; the oil phase is cooled, crystallized, and filtered to obtain a crude product (process 3), and the mother liquor of the crude product is used as a solvent for the next batch of reactions; the crude product is subjected to azeotropic distillation to remove the residual solvent, and DTBHQ is removed by hot filtration (process 4), and the filtrate is cooled, crystallized, and filtered to obtain a semi-finished product (process 5); the semi-finished product is recrystallized with a solvent (process 6), and finally filtered and vacuum dried to obtain a finished product (process 7).
[0004] Since the production method has a long process flow and undergoes multiple heating, stirring, cooling, crystallization and filtering operations, it is inevitable that there will be some contact with the air, resulting in the main product TBHQ and the by-product DTBHQ being oxidized to produce 2-tert-butyl-p-benzoquinone (TBQ) and 2,5-di-tert-butyl-p-benzoquinone (DTBQ). The total amount of TBQ and DTBQ is closely related to the degree of contact with air during operation and fluctuates greatly, which affects product quality, reduces product yield, increases the amount of solid waste treatment, and increases production costs. Summary of the invention
[0005] The present invention aims to provide a preparation method for inhibiting the production of oxidation by-products TBQ and DTBQ in the production process of antioxidant TBHQ in view of the problems existing in the existing production methods. By designing the process, the production of oxidation by-products TBQ and DTBQ is greatly reduced, the product quality and yield are improved, the three wastes are reduced, the cost is reduced, and the shelf life of the product is extended.
[0006] According to the first aspect of the object of the present invention, a preparation method of antioxidant TBHQ is provided, comprising the following steps:
[0007] S1. Add hydroquinone into a first solvent, add an acidic catalyst and a reducing agent, heat to a reaction temperature under nitrogen protection and maintain for a period of time, then introduce isobutene for alkylation reaction until the reaction end point is reached to obtain a first reactant;
[0008] S2. Separate the acidic catalyst in the first reactant to obtain a second reactant, and cool and crystallize the second reactant, and filter and separate to obtain a crude product;
[0009] S3. Add water and a reducing agent to the crude product, and perform azeotropic distillation under nitrogen protection until the first solvent is removed, then control the temperature to filter to remove insoluble DTBHQ, and the filtrate is cooled and crystallized and filtered to obtain a semi-finished product;
[0010] S4. Add the semi-finished product and a reducing agent to a second solvent, heat to complete dissolution under nitrogen protection and maintain for a period of time, then perform cooling crystallization, filtration, and vacuum drying to obtain antioxidant TBHQ.
[0011] As an optional implementation manner, the reducing agent includes unsaturated sulfide.
[0012] As an optional implementation manner, the first solvent includes toluene and / or xylene, the second solvent includes an aqueous ethanol solution, and the acidic catalyst includes phosphoric acid, sulfuric acid, a phosphoric acid mixture, and a strong acidic ion exchange resin type solid acid.
[0013] As an optional implementation manner, in the step S1, the usage amount of the reducing agent is 0.3-0.6% of the weight of the reaction substrate, the usage amount of the acidic catalyst is 1-4 times the weight of hydroquinone, and the usage amount of the first solvent needs to ensure that all products and remaining raw materials are dissolved after the reaction ends.
[0014] As an optional implementation manner, in the step S1, the reaction temperature is 80-100°C, and it is maintained for 15-30 min after heating.
[0015] As an optional implementation manner, in the step S3, the weight of water is set according to completely dissolving TBHQ in the crude product, and the usage amount of the reducing agent is 0.1-0.5% of the weight of water.
[0016] As an optional implementation manner, in the step S3, the temperature during filtration is controlled at 90-95°C.
[0017] As an optional implementation manner, in the step S4, the usage amount of the second solvent is 4-6 times the mass of the semi-finished product, the usage amount of the reducing agent is 1-1.5% of the mass of the second solvent, and it is heated to 40-60°C under nitrogen protection.
[0018] As an optional implementation manner, in the step S4, the conditions for vacuum drying are as follows: the vacuum degree is greater than 0.095 MPa, and the temperature is 90-110 °C.
[0019] According to the second aspect of the purpose of the present invention, there is provided an antioxidant TBHQ prepared by the foregoing method.
[0020] As can be seen from the technical solutions of the present invention above, in the preparation method of the antioxidant TBHQ proposed by the present invention, when carrying out the alkylation reaction between hydroquinone and isobutene, by setting the reducing agent to fully react with the oxygen in the material, subsequent oxidation side reactions are avoided. At the same time, in the nitrogen protection atmosphere, the consumption rate of the reducing agent during the reaction process is slowed down, enabling it to continuously play an antioxidant role during the inevitable air-contact processes such as liquid-liquid separation and solid-liquid filtration. At the same time, it can also greatly reduce the oxidation of the separated and recovered acidic catalyst and the crude product mother liquor during the waiting process for reuse, improving the purity of the crude product; on this basis, subsequent treatment of the crude product is carried out under the atmosphere of the reducing agent and nitrogen protection, avoiding or minimizing the occurrence of oxidation side reactions, and greatly reducing the generation amount of the final oxidation by-products TBQ and DTBQ.
[0021] The preparation method of the present invention, through the double protection of nitrogen and reducing agent throughout the process, reduces the generation amount of oxidation by-products TBQ and DTBQ, improves the product quality and yield, reduces the three wastes, reduces the cost, and can extend the product shelf life. Description of the Drawings
[0022] Figure 1 It is the GC chromatogram of reactant 1 in the embodiment of the present invention.
[0023] Figure 2 It is the GC chromatogram of semi-finished product 1 in the embodiment of the present invention.
[0024] Figure 3 It is the GC chromatogram of finished product 1 in the embodiment of the present invention.
[0025] Figure 4 It is the GC chromatogram of reactant 2 in the embodiment of the present invention.
[0026] Figure 5 It is the GC chromatogram of semi-finished product 2 in the embodiment of the present invention.
[0027] Figure 6 It is the GC chromatogram of finished product 2 in the embodiment of the present invention.
[0028] Figure 7 It is the physical diagram of finished product 1 and finished product 2 of the present invention. Detailed Embodiments
[0029] To better understand the technical content of the present invention, specific embodiments are hereby given and described in conjunction with the accompanying drawings as follows.
[0030] In the present disclosure, aspects of the present invention are described with reference to the accompanying drawings, in which numerous illustrative embodiments are shown. The embodiments of the present disclosure are not necessarily intended to cover all aspects of the present invention. It should be understood that the various concepts and embodiments introduced above, as well as those described in more detail below, can be implemented in any of many ways.
[0031] The present invention aims to provide a preparation method for suppressing the production amount of oxidation by-products TBQ and DTBQ during the production of antioxidant TBHQ. Hydroquinone is added with a certain amount of reducing agent in the presence of an acidic catalyst and a solvent, and under nitrogen protection, it is heated to the reaction temperature and maintained for a certain time, and then isobutene is introduced for alkylation reaction; after the reaction is completed, the acidic catalyst in the acid phase is separated while it is hot, and the oil phase is cooled, crystallized, and filtered to obtain a crude product. A certain amount of water and a reducing agent are added to the crude product, and under nitrogen protection, azeotropic distillation is carried out to remove the residual solvent, and DTBHQ that is insoluble is removed by filtration while it is hot. The filtrate is cooled, crystallized, and filtered to obtain a semi-finished product, and the semi-finished product is recrystallized with a solvent, and finally, a white finished product TBHQ is obtained through filtration and vacuum drying.
[0032] In an exemplary embodiment of the present invention, a preparation method for antioxidant TBHQ is provided, including the following steps:
[0033] S1. Hydroquinone is added to a first solvent, and an acidic catalyst and a reducing agent are added. Under nitrogen protection, it is heated to the reaction temperature and maintained for a period of time, and then alkylation reaction is carried out with isobutene until the reaction end point to obtain a first reactant;
[0034] Among them, heating to the reaction temperature and maintaining for a certain time under nitrogen protection is to enable the reducing agent to fully react with the oxygen dissolved in materials such as the first solvent, so as to avoid subsequent oxidation side reactions. At the same time, under nitrogen protection, the consumption rate of the reducing agent during the reaction process can be slowed down as much as possible, so that it can continuously play an antioxidant role during the subsequent inevitable processes of liquid-liquid separation and solid-liquid filtration that contact air, and can also greatly reduce the oxidation of the separated and recovered acidic catalyst and the crude product mother liquor during the waiting process for reuse.
[0035] S2. The acidic catalyst in the first reactant is separated to obtain a second reactant, and the second reactant is cooled, crystallized, and filtered to obtain a crude product.
[0036] S3. Water and a reducing agent are added to the crude product, and azeotropic distillation is carried out under nitrogen protection until the first solvent is removed, and then the temperature is controlled for filtration to remove insoluble DTBHQ. The filtrate is cooled, crystallized, and filtered to obtain a semi-finished product;
[0037] Among them, a certain amount of water and a reducing agent are added to the crude product. Firstly, based on the principle of azeotropy between the first solvent and water, the first solvent entrained in the crude product is completely removed. Secondly, a small amount of unreacted HQ is dissolved to achieve the purpose of separating and purifying the product and recycling the raw materials. Thirdly, taking advantage of the fact that TBHQ is soluble in hot water but insoluble in cold water, while DTBHQ is insoluble in hot water, the by-product DTBHQ can be separated; the reducing agent and the nitrogen protection atmosphere avoid or minimize the occurrence of oxidation side reactions.
[0038] S4. Add the semi-finished product and the reducing agent into the second solvent, heat to complete dissolution under the protection of nitrogen, maintain for a period of time, and then carry out cooling crystallization, filtration, and vacuum drying to obtain the antioxidant TBHQ.
[0039] Based on the previous steps, the purity of the semi-finished product is greatly improved, and the oxidation side reaction is inhibited. Continuing with recrystallization in the presence of the reducing agent and the nitrogen protection atmosphere, a small amount of impurities such as TBQ, DTBQ, HQ, and DTBHQ are removed, greatly improving the final product yield, with fewer oxidation by-products, and the product purity reaching a quality index of greater than 99%. The product quality is high; the role of the reducing agent not only avoids oxidation side reactions during cooling crystallization and filtration but also provides antioxidant protection for the storage period of the dried finished product.
[0040] As an alternative embodiment, the reducing agent includes unsaturated sulfides.
[0041] In a preferred embodiment, the reducing agent includes sodium sulfite, sodium bisulfite, sodium metabisulfite, sodium dithionite (sodium hydrosulfite), sulfur dioxide, etc., and sodium hydrosulfite is particularly preferred.
[0042] As an alternative embodiment, the first solvent includes toluene and / or xylene, the second solvent includes an aqueous ethanol solution, and the acidic catalyst includes phosphoric acid, sulfuric acid, a mixture of phosphoric acids, and solid acids of strongly acidic ion exchange resin type.
[0043] As an alternative embodiment, in step S1, the usage amount of the reducing agent is 0.3 - 0.6% of the weight of the reaction substrate, the usage amount of the acidic catalyst is 1 - 4 times the weight of hydroquinone, and the usage amount of the first solvent needs to ensure that all products and remaining raw materials are completely dissolved after the reaction is completed, so as to be smoothly separated from the acidic catalyst by liquid-liquid separation. Generally, it is about 6 - 10 times the weight of HQ.
[0044] It can be understood that the reaction substrate refers to the weight of all materials put into the reactor.
[0045] As an alternative embodiment, in step S1, the reaction temperature is 80 - 100 °C, and after heating, it is maintained for 15 - 30 min.
[0046] As an alternative embodiment, in step S3, the weight of water is set according to the complete dissolution of TBHQ in the crude product. The dosage of the reducing agent is 0.1-0.5% of the weight of water. Preferably, the water consumption is about 35 times the weight of TBHQ, so as to control the complete dissolution of TBHQ in hot water, and minimize the TBHQ entrained in DTBHQ. The dosage of the reducing agent is 0.1-0.5% of the weight of water.
[0047] As an alternative embodiment, in step S3, the temperature during filtration is controlled at 90-95°C.
[0048] As an alternative embodiment, in step S4, the dosage of the second solvent is 4-6 times the mass of the semi-finished product, and the dosage of the reducing agent is 1-1.5% of the mass of the second solvent. Heat it to 40-60°C under the protection of nitrogen and maintain for 15-30 minutes after heating.
[0049] As an alternative embodiment, in step S4, the conditions for vacuum drying are: the vacuum degree is greater than 0.095 MPa and the temperature is 90-110°C.
[0050] In another exemplary embodiment of the present invention, an antioxidant TBHQ prepared by the aforementioned method is also provided. The purity of TBHQ is as high as 99%, the product quality is high, and the shelf life is long.
[0051] For better understanding, the present invention will be further described below in conjunction with several specific examples, but the preparation process is not limited thereto, and the content of the present invention is not limited thereto.
[0052] Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.
[0053] Example 1
[0054] Add 20 g of HQ, 40 g of 70% phosphoric acid, 160 mL of xylene, and 0.6 g of sodium dithionite to a 500 mL four-necked flask. Under nitrogen protection, heat it to 90°C and maintain for 0.5 hour, then pass isobutene and react for 5 hours to obtain reactant 1.
[0055] Separate the lower phosphoric acid phase from the reactant. Cool and crystallize the upper oil phase under nitrogen protection and filter it to obtain the crude product. Transfer it to a four-necked flask, add 450 mL of water and 0.8 g of sodium dithionite, and recover the residual xylene by azeotropic distillation under nitrogen protection. Then filter at 90°C, cool and crystallize the filtrate and filter it to obtain the semi-finished product TBHQ, denoted as semi-finished product 1.
[0056] Add the semi-finished product into a 500 mL four-necked flask, add 100 g of 10% alcohol solution and 0.75 g of sodium dithionite, heat to complete dissolution under nitrogen protection, about 65 °C, maintain for 0.5 hours, cool and crystallize, filter, and dry at -0.095 MPa and 90 °C for 2 hours to obtain a white TBHQ finished product, denoted as Finished Product 1.
[0057] Comparative Example 1
[0058] Add 20 g of HQ, 40 g of 70% phosphoric acid, and 160 mL of xylene into a 500 mL four-necked flask, heat to 90 °C, and react with isobutene for 5 hours to obtain Reactant 2.
[0059] Separate the lower phosphoric acid phase from the reactant. The upper oil phase is cooled and crystallized under nitrogen protection and then filtered to obtain the crude product. Transfer it into a four-necked flask, add 450 mL of water, and recover the residual xylene by azeotropic distillation. Then filter at 90 °C. The filtrate is cooled, crystallized, and filtered to obtain the semi-finished product TBHQ, denoted as Semi-finished Product 2.
[0060] Add the semi-finished product into a 500 mL four-necked flask, add 100 g of 10% alcohol solution, heat to complete dissolution, about 65 °C, maintain for 0.5 hours, cool and crystallize, filter, and dry at -0.095 MPa and 90 °C for 2 hours to obtain a beige TBHQ finished product, denoted as Finished Product 2.
[0061] Analysis and Testing
[0062] Conduct a composition analysis on the products in Example 1 and Comparative Example 1, and the results are as Figures 1-6 , and shown in Table 1.
[0063] Table 1
[0064]
[0065]
[0066] The above comparative examples show that in the TBHQ preparation method of the present invention, after adopting double protection of nitrogen and reducing agent in the whole process, the generation amounts of oxidation by-products TBQ and DTBQ are greatly reduced, and the finished product has less impurities. Compared with the finished product of the comparative example, as Figure 7 shown, the color is whiter, and the content of TBHQ is as high as 98.82%.
[0067] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the present invention pertains can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to what is defined by the claims.
Claims
1. A preparation method of antioxidant TBHQ, characterized in that, It includes the following steps: S1. Add hydroquinone into the first solvent, and add an acidic catalyst and a reducing agent. After heating to the reaction temperature under nitrogen protection and maintaining for a period of time, then introduce isobutene for alkylation reaction until the reaction end point to obtain a first reactant; S2. Separate the acidic catalyst in the first reactant to obtain a second reactant, and cool and crystallize the second reactant, and filter and separate to obtain a crude product; S3. Add water and a reducing agent to the crude product, and perform azeotropic distillation under nitrogen protection until the first solvent is removed, then control the temperature to filter out the insoluble DTBHQ, and the filtrate is cooled, crystallized, and filtered to obtain a semi-finished product; S4. Add the semi-finished product and a reducing agent to the second solvent, and heat to complete dissolution under nitrogen protection and maintain for a period of time, then perform cooling crystallization, filtration, and vacuum drying to obtain the antioxidant TBHQ.
2. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, The reducing agent includes unsaturated sulfide.
3. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, The first solvent includes toluene and / or xylene, the second solvent includes an aqueous ethanol solution, and the acidic catalyst includes phosphoric acid, sulfuric acid, a phosphoric acid mixture, and a solid acid of a strongly acidic ion exchange resin type.
4. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, In the step S1, the usage amount of the reducing agent is 0.3 - 0.6% of the weight of the reaction substrate, the usage amount of the acidic catalyst is 1 - 4 times the weight of hydroquinone, and the usage amount of the first solvent needs to ensure that all products and remaining raw materials are dissolved after the reaction ends.
5. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, In the step S1, the reaction temperature is 80 - 100 °C, and it is maintained for 15 - 30 min after heating.
6. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, In the step S3, the weight of water is set according to completely dissolving the TBHQ in the crude product, and the usage amount of the reducing agent is 0.1 - 0.5% of the weight of water.
7. The preparation method of antioxidant TBHQ according to claim 1, characterized in that In the step S3, the temperature during filtration is controlled at 90 - 95 °C.
8. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, In the step S4, the usage amount of the second solvent is 4 - 6 times the mass of the semi-finished product, the usage amount of the reducing agent is 1 - 1.5% of the mass of the second solvent, and it is heated to 40 - 60 °C under nitrogen protection.
9. The preparation method of antioxidant TBHQ according to claim 1, characterized in that, In the step S4, the conditions for vacuum drying are: the vacuum degree is greater than 0.095 MPa, and the temperature is 90 - 110 °C.
10. An antioxidant TBHQ prepared by the method according to any one of claims 1 - 9.