A method for purifying tmq dimers
By improving the post-processing technology of TMQ production and adopting atmospheric distillation and organic solvent crystallization methods, the problem of insufficient purity of TMQ dimer in the existing technology has been solved, and the production of high-purity TMQ dimer has been realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2022-10-26
- Publication Date
- 2026-06-30
AI Technical Summary
Existing technologies make it difficult to produce high-purity TMQ dimers, especially since the dimer content is difficult to meet the requirements of high-end fields.
By improving the post-processing, including evaporating water and acetone components under normal pressure, removing aniline and monomer fractions under vacuum distillation, and then dissolving and cooling in an organic solvent to crystallize, a high-purity TMQ dimer product is obtained.
The content of TMQ dimer in the finished product reached over 98%, meeting the requirements of high-end fields.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for purifying TMQ dimers, belonging to the field of fine chemical technology. Background Technology
[0002] Antioxidant TMQ, also known as antioxidant RD, is a di, tri, and tetrapolymer of 2,2,4-trimethyl-1,2-dihydroquinoline. It is primarily used as an antioxidant in rubber and rubber products, suitable for natural rubber, synthetic rubber, and latex. It strongly inhibits the catalytic oxidation of harmful metal ions such as copper and manganese, exhibits good compatibility with rubber, low volatility, minimal blooming, and high resistance to extraction. It is widely used in the domestic and international rubber processing industry; it is required for ordinary tires, radial tires, and other rubber products to achieve better protective performance.
[0003] The antioxidant TMQ is produced by first condensing aniline and acetone under acidic conditions to form the monomer TMDQ (2,2,4-trimethyl-1,2-dihydroquinoline), then polymerizing TMDQ to form dimers, trimers, and tetramers. The resulting reaction solution is neutralized with liquid alkali and distilled to obtain TMQ. The main principle of synthesizing TMQ using hydrochloric acid as a catalyst is as follows:
[0004] Main reaction:
[0005]
[0006] ;
[0007] Side reactions leading to the formation of primary amines:
[0008]
[0009]
[0010] .
[0011] Under acidic conditions, acetone and aniline may undergo various other side reactions. According to relevant reports, there are more than 70 products. Among them, the dimers, trimers and tetramers are the main ones that play an anti-aging role in rubber processing. In particular, the dimers have more outstanding anti-heat aging and anti-ozone oxidation properties for rubber products or oils.
[0012] Currently, in the existing production methods of antioxidant TMQ both domestically and internationally, the control of dimer is mainly achieved by adjusting the synthesis process conditions. The resulting products have an effective content between 40% and 70%, of which the dimer content is between 20% and 50% (GB / T 8826-2019), which is insufficient to meet the requirements of high-end fields. Summary of the Invention
[0013] The purpose of this invention is to overcome the defects of the existing technology and to achieve the production of high-purity dimer TMQ by improving the post-processing process during TMQ production.
[0014] This invention provides a method for purifying TMQ dimers, which is achieved through the following steps: crude TMQ, generated by the polycondensation reaction of aniline, catalyst, and acetone, is evaporated to remove water and acetone components under normal pressure. Then, aniline and monomer fractions are removed by distillation under vacuum (0.09-0.099 MPa) (below 200°C). After distillation, the temperature is further increased, and the fraction mainly composed of dimers is collected. After distillation, the fraction is dissolved by heating and stirring with an organic solvent, cooled and crystallized, and then filtered and dried to obtain a high-purity TMQ dimer product.
[0015] Generally, the vapor phase temperature for distilling the dimer is 200-300℃, preferably 200-250℃.
[0016] The vacuum degree of the distilled dimer is controlled at 0.095-0.099 MPa.
[0017] The organic solvent is methanol, ethanol, isopropanol, benzene, toluene, xylene, or a combination thereof in any proportion or composition thereof.
[0018] The mass ratio of the organic solvent to the dimer fraction is 1-10, preferably 3-5.
[0019] The dissolution temperature is 20-200℃, preferably the boiling point temperature of a single solvent or a mixture of solvents under normal pressure.
[0020] The dissolution time is 30-120 minutes, preferably 60-100 minutes.
[0021] The crystallization temperature is 20-40℃, preferably 25-30℃.
[0022] Invention Effects
[0023] Using the method of this invention, the content of TMQ dimer in the finished product can reach more than 98%. Detailed Implementation
[0024] The present invention will now be described in detail with reference to embodiments.
[0025] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other.
[0026] Example 1
[0027] Add 2000 g of crude TMQ to a distillation flask equipped with a stirrer and thermometer. After adding, heat the flask while stirring, and distill off the fraction with a vapor temperature below 100°C under normal pressure. Then, apply a vacuum (0.095-0.099 MPa) and continue heating, controlling the heating rate at 1-2°C per minute. Distill off aniline and monomer fractions below 200°C. Collect the fraction with a predominantly dimer content at 200-250°C, weighing approximately 600 g. After distillation, cool the flask, release the vacuum, and add the dimer fraction to a four-necked flask equipped with a stirrer, thermometer, and condenser, pre-filled with 1800 g of methanol (methanol to dimer fraction mass ratio of 3:1). Raise the temperature to reflux with the solvent methanol within 60-80 minutes, maintain stirring for 60 minutes, and then cool to 25-30°C for crystallization. Filter and dry to obtain 360 g of the final product. The dimer content is analyzed to be 99.5%, and the melting point is 97°C.
[0028] Example 2
[0029] Other conditions were the same as in Example 1, except that the mass ratio of methanol to dimer fraction was 2:1, yielding 450 grams of the final product. The dimer content was analyzed to be 98%, and the melting point was 96°C.
[0030] Example 3
[0031] Other conditions were the same as in Example 1, except that the mass ratio of methanol to dimer fraction was 4:1, yielding 320 grams of finished product. The dimer content was analyzed to be 99.6%, and the melting point was 97.2°C.
[0032] Example 4
[0033] Other conditions were the same as in Example 1, except that the mass ratio of methanol to dimer fraction was 5:1, yielding 270 grams of finished product. The dimer content was analyzed to be 99.8%, and the melting point was 97.5°C.
[0034] Example 5
[0035] Other conditions were the same as in Example 1, except that ethanol was used instead of methanol to obtain 340 grams of the finished product, with a dimer content of 98.1% and a melting point of 96°C.
[0036] Example 6
[0037] Other conditions were the same as in Example 1, except that isopropanol was used instead of methanol to obtain 360 grams of the finished product, with a dimer content of 98.2% and a melting point of 96°C.
[0038] Example 7
[0039] Other conditions were the same as in Example 1, except that benzene was used instead of methanol to obtain 380 grams of the finished product, with a dimer content of 98.1% and a melting point of 96°C.
[0040] Example 8
[0041] Other conditions were the same as in Example 1, except that xylene was used instead of methanol to obtain 370 grams of the finished product, with a dimer content of 98.2% and a melting point of 96°C.
[0042] Example 9
[0043] Other conditions were the same as in Example 1, except that a mixture of methanol and ethanol in a mass ratio of 1:1 was used instead of methanol to obtain 350 grams of the finished product. The analysis showed that the dimer content was 99.1% and the melting point was 97°C.
[0044] Example 10
[0045] Other conditions were the same as in Example 1, except that a mixture of methanol and isopropanol in a mass ratio of 1:1 was used instead of methanol to obtain 355 grams of the finished product. The analysis showed that the dimer content was 98.3% and the melting point was 96.5°C.
[0046] Example 11
[0047] Other conditions were the same as in Example 1, except that a mixture of methanol and benzene in a mass ratio of 1:1 was used instead of methanol to obtain 370 grams of finished product. The analysis showed that the dimer content was 98.1% and the melting point was 96°C.
[0048] Example 12
[0049] Other conditions were the same as in Example 1, except that a mixture of xylene and benzene in a mass ratio of 1:1 was used instead of methanol to obtain 368 grams of the finished product. The analysis showed that the dimer content was 98% and the melting point was 96°C.
[0050] Example 13
[0051] Other conditions were the same as in Example 1, except that the crystallization temperature was 40°C, yielding 300 grams of the finished product. The analysis showed that the dimer content was 99.3% and the melting point was 96.8°C.
[0052] Example 14
[0053] Other conditions were the same as in Example 1, except that the crystallization temperature was 10°C, yielding 400 grams of the finished product. The analysis showed that the dimer content was 98.3% and the melting point was 96.2°C.
[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. For those skilled in the art, the present invention can be modified and varied in various ways, such as changing the feeding method and the reactor. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A method for purifying TMQ dimers, characterized in that: The crude TMQ product, obtained by polycondensation of aniline, catalyst, and acetone, is distilled off with water and acetone under normal pressure. Then, under a vacuum of 0.09-0.099 MPa, aniline and monomer fractions below 200℃ are removed by distillation. After distillation, the temperature is further increased, and under a vacuum of 0.095-0.099 MPa, the gas phase fraction mainly composed of dimers at 200-250℃ is collected. After distillation, the fraction is dissolved in an organic solvent by heating and stirring, cooled and crystallized, filtered and dried to obtain high-purity TMQ dimer product. The organic solvent is methanol, ethanol, isopropanol, benzene, toluene, xylene, or a combination thereof in any proportion or composition thereof.
2. The method according to claim 1, characterized in that, The mass ratio of organic solvent to dimer fraction is 1-10.
3. The method according to claim 2, characterized in that, The mass ratio of organic solvent to dimer fraction is 3-5.
4. The method according to claim 1, characterized in that, The dissolution temperature is 20-200℃.
5. The method according to claim 4, characterized in that, The dissolution temperature is the boiling point of a single solvent or a mixture of solvents at normal pressure.
6. The method according to claim 1, characterized in that, The dissolution time is 30-120 minutes.
7. The method according to claim 6, characterized in that, The dissolution time is 60-100 minutes.
8. The method according to claim 1, characterized in that, The crystallization temperature is 20-40℃.
9. The method according to claim 8, characterized in that, The crystallization temperature is 25-30℃.
10. The method according to claim 1, characterized in that, The TMQ dimer content in the finished TMQ dimer product reaches over 98%.