Method for preparing trimesic acid

Abstract

The invention relates to the technical field of trimesic acid, and discloses a method for preparing trimesic acid, which comprises the following step: carrying out oxidation reaction on mesitylene in a liquid phase catalysis system containing a phase transfer agent and water to obtain trimesic acid. By adopting the method disclosed by the invention, the oxidation reaction of mesitylene can be carried out in water, so that the corrosion of the oxidation reaction of mesitylene to equipment is reduced, and the requirement on the equipment is reduced. By adopting the method disclosed by the invention, not only can the purity of the trimesic acid product be improved, but also higher yield of the trimesic acid product can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of trimellitic acid, and particularly relates to a method for preparing trimellitic acid. Background Art

[0002] Trimellitic acid, also known as 1,3,5-benzenetricarboxylic acid, is an important chemical raw material and an intermediate for the production of special polymers and resins, with very wide applications. It can be used to synthesize alkyd resins with polyols and make water-soluble baking paints; it can be used as a curing crosslinking agent for unsaturated resins; it can be used to manufacture aromatic polyimide-polysulfone reverse osmosis membranes for seawater desalination and the production of ultrapure water; its esters are also a kind of high-grade plasticizers. Trimellitic acid can also be used in the military industry as a crosslinking agent for solid rocket fuels. Therefore, it is of great significance for the production of plastics, synthetic fibers, water-soluble alkyl resins, plasticizers, fungicides, mildew-proof agents, crosslinking agents, etc.

[0003] There have been many studies on the preparation methods of trimellitic acid at home and abroad. There are roughly three methods: the oxidation of mesitylene with potassium permanganate, the oxidation of mesitylene with nitric acid, and the liquid-phase air oxidation of mesitylene. Among them, in the potassium permanganate oxidation method, a large amount of wastewater and waste residue are generated during the reaction process, the post-treatment is difficult, the conversion rate is low, and the purification is complex; in the nitric acid method, the raw material cost is high, the selectivity is poor, the product yield does not exceed 70%, the purification of the crude product is difficult, and the environmental pollution and the production process are highly dangerous.

[0004] In the usual liquid-phase air oxidation method, glacial acetic acid is used as a solvent, and cobalt acetate is used as a catalyst at a pressure of 2 - 4 MPa and a temperature of 100°C - 250°C, and air is passed to oxidize mesitylene to obtain trimellitic acid. The production process of this method is relatively mature, but using acetic acid as a solvent requires high equipment requirements. And directly replacing acetic acid with water will cause a significant reduction in the product yield. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned technical problems existing in the prior art, and provide a method for preparing trimellitic acid, which can improve the product yield of preparing trimellitic acid with water as a solvent.

[0006] To achieve the above purpose, the present invention provides a method for preparing trimellitic acid, which includes: in a liquid-phase catalytic system containing a phase transfer agent and water, subjecting mesitylene to an oxidation reaction to obtain trimellitic acid.

[0007] Through the above technical solutions, the present invention has the following beneficial effects:

[0008] (1) By using the method of the present invention, the oxidation reaction of mesitylene can be carried out in water, reducing the corrosion of the mesitylene oxidation reaction to the equipment and reducing the requirements for the equipment.

[0009] (2) Using the method of the present invention can not only ensure the improvement of the purity of the trimellitic acid product, but also obtain a relatively high yield of the trimellitic acid product. Detailed implementation manners

[0010] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0011] In the present invention, unless otherwise specified, the "room temperature" refers to 20 - 30 °C.

[0012] The present invention provides a method for preparing trimellitic acid, which method comprises: in a liquid-phase catalytic system containing a phase transfer agent and water, subjecting mesitylene to an oxidation reaction to obtain trimellitic acid.

[0013] According to the present invention, the phase transfer agent can be a conventional substance having a phase transfer function. However, in order to improve the yield of trimellitic acid, preferably, the phase transfer agent is at least one of tetrabutylammonium bromide, polyethylene glycol, and crown ether (such as 18-crown-6 ether), and more preferably tetrabutylammonium bromide. When the present invention uses tetrabutylammonium bromide, a relatively high yield and purity of trimellitic acid can still be maintained under the condition of a relatively low dosage of the catalyst.

[0014] According to the present invention, preferably, the liquid-phase catalytic system further contains a catalyst, and the catalyst includes an organic cobalt salt, an organic manganese salt, and a bromide.

[0015] According to the present invention, preferably, the organic cobalt salt is cobalt naphthenate and / or cobalt acetate, and more preferably cobalt naphthenate. The number of carbon atoms of naphthenic acid in cobalt naphthenate can be 20 - 25. For example, the molecular formula of cobalt naphthenate can be C 22 H 16 CoO4.

[0016] According to the present invention, preferably, the organic manganese salt is manganese naphthenate and / or manganese acetate, and preferably manganese naphthenate. The number of carbon atoms of naphthenic acid in manganese naphthenate can be 20 - 25. For example, the molecular formula of manganese naphthenate can be C 22 H 14 MnO4.

[0017] According to the present invention, preferably, the bromide is an alkali metal bromide and / or hydrogen bromide; more preferably sodium bromide. The bromide can be used as a promoter to initiate the oxidation reaction of mesitylene.

[0018] According to the present invention, preferably, relative to every 100 g of mesitylene, the dosage of the organic cobalt salt is 0.1 - 6 g, more preferably 0.3 - 5.1 g; the dosage of the organic manganese salt is 0.1 - 11 g, more preferably 0.8 - 10.1 g; the dosage of the bromide is 0.1 - 12 g, more preferably 0.7 - 10.5 g. Limiting the organic cobalt salt, the organic manganese salt and the bromide within the above ranges can further improve the yield and purity of trimellitic acid.

[0019] According to the present invention, preferably, relative to every 100 g of mesitylene, the dosage of water is 400 - 2000 g, more preferably 500 - 1800 g; the dosage of the phase transfer agent is 0.3 - 3 g, more preferably 0.4 - 2.1 g.

[0020] According to the present invention, the temperature of the oxidation reaction is 150 - 200 °C, preferably 160 - 190 °C; the time of the oxidation reaction is 10 - 15 h, preferably 11 - 13 h.

[0021] According to the present invention, the pressure of the oxidation reaction is 1 - 3 MPa, preferably 2 - 2.5 MPa. The oxidation reaction of the present invention is carried out in a high-pressure reactor (such as a high-pressure autoclave), and the high-pressure reactor is equipped with a temperature detection device and a pressure detection device for detecting the temperature and pressure during the reaction process. The high-pressure reactor also includes a stirring device, and the stirring device makes the oxidation reaction proceed under a stirring state. Preferably, the rotation speed of the stirring can be 300 - 400 rpm.

[0022] In the present invention, before the oxidation reaction starts, first put mesitylene and water into the high-pressure reactor, add the organic cobalt salt, the organic manganese salt, the bromide and the phase transfer agent under a stirring state, then heat up to 150 - 200 °C at a rate of 5 - 10 °C / min, and then introduce air, and keep stirring and reacting at this temperature for 10 - 15 h.

[0023] According to the present invention, preferably, during the oxidation reaction, relative to every 100 g of mesitylene, the air flow rate is 1 - 3 L / min, more preferably 1.5 - 2 L / min.

[0024] According to a particularly preferred embodiment of the present invention, the method for preparing trimellitic acid includes: adding 100 g of mesitylene and 1100 - 1200 g of water solvent into a high-pressure autoclave, then adding 2.5 - 3.5 g of cobalt naphthenate and 5 - 6 g of manganese naphthenate, then adding 5 - 6 g of sodium bromide and 1 - 1.5 g of tetrabutylammonium bromide, heating up to 180 - 185 °C at a rate of 5 - 7 °C / min, raising the pressure to 2 - 2.2 MPa, introducing air at a flow rate of 1.8 - 2 L / min, and stirring for 11 - 12 h.

[0025] The present invention will be described in detail below through examples. In the following examples,

[0026] The catalytic products were analyzed by chromatographic analysis and chemical titration methods;

[0027] The calculation formula for the yield (%) of trimellitic acid is:

[0028]

[0029] M 均苯三甲酸 is the molecular weight of trimellitic acid, 210.1; M 均三甲苯 is the molecular weight of mesitylene, 120.2

[0030] All raw materials used below are commercially available products.

[0031] Among them, cobalt naphthenate and manganese naphthenate are both commercially available products of Tokyo Chemical Industry Co., Ltd. The number of carbon atoms in naphthenic acid in cobalt naphthenate and manganese naphthenate is 22. The molecular formula of cobalt naphthenate is C 22 H 16 CoO4. The molecular formula of manganese naphthenate is C 22 H 14 MnO4.

[0032] Example 1

[0033] In a 3000 ml autoclave, 100 g of mesitylene and 1200 g of water solvent were added to the autoclave. Under stirring at room temperature (rotation speed of 350 rpm), 3 g of cobalt naphthenate and 6 g of manganese naphthenate were added, then 5 g of sodium bromide and 1 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 1.8 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain a filter cake, and the product was obtained after drying.

[0034] Example 2

[0035] In a 3000 ml autoclave, 100 g of mesitylene and 500 g of water solvent were added to the autoclave. Under stirring at room temperature (rotation speed of 350 rpm), 0.5 g of cobalt naphthenate and 1 g of manganese naphthenate were added, then 1 g of sodium bromide and 0.5 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 1.5 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain a filter cake, and the product was obtained after drying.

[0036] Example 3

[0037] In a 3000 ml autoclave, 100 g of mesitylene and 1800 g of water solvent were added to the autoclave. 5 g of cobalt naphthenate and 10 g of manganese naphthenate were added under stirring at room temperature (rotation speed: 350 rpm). Then, 10 g of sodium bromide and 2 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 2 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain the product.

[0038] Example 4

[0039] In a 3000 ml autoclave, 100 g of mesitylene and 1200 g of water solvent were added to the autoclave. 0.5 g of cobalt naphthenate and 1 g of manganese naphthenate were added under stirring at room temperature (rotation speed: 350 rpm). Then, 1 g of sodium bromide and 1 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 1.8 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain the product.

[0040] Example 5

[0041] In a 3000 ml autoclave, 100 g of mesitylene and 1200 g of water solvent were added to the autoclave. 5 g of cobalt naphthenate and 10 g of manganese naphthenate were added under stirring at room temperature (rotation speed: 350 rpm). Then, 10 g of sodium bromide and 1 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 2 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain the product.

[0042] Example 6

[0043] In a 3000 ml autoclave, 100 g of mesitylene and 1200 g of water solvent were added to the autoclave. 3 g of cobalt naphthenate and 6 g of manganese naphthenate were added under stirring at room temperature (rotation speed: 350 rpm). Then, 5 g of sodium bromide and 0.5 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 1.8 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain the product.

[0044] Example 7

[0045] In a 3000 ml autoclave, 100 g of mesitylene and 1200 g of water solvent were added to the autoclave. Under stirring at room temperature (rotation speed of 350 rpm), 3 g of cobalt naphthenate and 6 g of manganese naphthenate were added, then 5 g of sodium bromide and 2 g of tetrabutylammonium bromide were added. The temperature was raised to 180 °C at a rate of 5 °C / min, and the pressure was raised to 2.2 MPa. Air was introduced at a flow rate of 1.8 L / min, and stirring was carried out for 12 h. After cooling to room temperature, it was centrifuged and dried to obtain a filter cake, and the product was obtained after drying.

[0046] Example 8

[0047] The method of Example 1 was followed, except that tetrabutylammonium bromide was replaced with an equal weight of polyethylene glycol.

[0048] Example 9

[0049] The method of Example 1 was followed, except that tetrabutylammonium bromide was replaced with an equal weight of 18-crown-6 ether.

[0050] Example 10

[0051] The method of Example 1 was followed, except that cobalt naphthenate was replaced with an equal weight of cobalt acetate, and manganese naphthenate was replaced with an equal weight of manganese acetate.

[0052] Example 11

[0053] The method of Example 1 was followed, except that tetrabutylammonium bromide was replaced with an equal weight of tetrabromoethane.

[0054] Example 12

[0055] The method of Example 1 was followed, except that tetrabutylammonium bromide was replaced with an equal weight of triethanolamine.

[0056] Comparative Example 1

[0057] The method of Example 1 was followed, except that tetrabutylammonium bromide was not added.

[0058] Comparative Example 2

[0059] The method of Example 2 was followed, except that tetrabutylammonium bromide was not added.

[0060] Comparative Example 3

[0061] The method of Example 3 was followed, except that tetrabutylammonium bromide was not added.

[0062] Table 1

[0063]

[0064]

[0065] As can be seen from the results in Table 1, compared with the comparative examples, the method of the present invention can improve the yield of trimellitic acid product. The preferred embodiments 1-10 of the present invention are used to further improve the yield of trimellitic acid product. In addition, by comparing Examples 11-12 with Examples 1 and 8-9, it can be found that by using the specific phase transfer agent of the present invention, a trimellitic acid product with a high yield can be obtained in a reaction system using water as the medium.

[0066] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing trimellitic acid, characterized in that, The method includes: subjecting mesitylene to an oxidation reaction in a liquid-phase catalytic system containing a phase transfer agent and water to obtain trimellitic acid.

2. The method according to claim 1, wherein, The phase transfer agent is at least one of tetrabutylammonium bromide, polyethylene glycol, and crown ether, preferably tetrabutylammonium bromide.

3. The method according to claim 2, wherein, The liquid-phase catalytic system further contains a catalyst, and the catalyst includes an organic cobalt salt, an organic manganese salt, and a bromide.

4. The method according to claim 3, wherein The organic cobalt salt is cobalt naphthenate and / or cobalt acetate, preferably cobalt naphthenate.

5. The method according to claim 3, wherein, The organic manganese salt is manganese naphthenate and / or manganese acetate, preferably manganese naphthenate.

6. The method according to claim 3, wherein, The bromide is an alkali metal bromide and / or hydrogen bromide; preferably sodium bromide.

7. The method according to any one of claims 3-6, wherein, Relative to every 100 g of mesitylene, the dosage of the organic cobalt salt is 0.1 - 6 g, preferably 0.3 - 5.1 g; the dosage of the organic manganese salt is 0.1 - 11 g, preferably 0.8 - 10.1 g; the dosage of the bromide is 0.1 - 12 g, preferably 0.7 - 10.5 g.

8. The method according to any one of claims 1-6, wherein, Relative to every 100 g of mesitylene, the dosage of water is 400 - 2000 g, preferably 500 - 1800 g; the dosage of the phase transfer agent is 0.3 - 3 g, preferably 0.4 - 2.1 g.

9. The method according to any one of claims 1-6, wherein, The temperature of the oxidation reaction is 150 - 200 °C, preferably 160 - 190 °C; the time of the oxidation reaction is 10 - 15 h, preferably 11 - 13 h; and / or, the pressure of the oxidation reaction is 1 - 3 MPa, preferably 2 - 2.5 MPa.

10. The method according to any one of claims 1-6, wherein, During the oxidation reaction, relative to every 100 g of mesitylene, the air flow rate is 1 - 3 L / min, preferably 1.5 - 2 L / min.

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