Preparation method of high content type antioxidant tmq

Abstract

The application belongs to the technical field of fine chemical industry, and provides a preparation method of high-content antioxidant TMQ. The ordinary TMQ with low effective content is dissolved in a composite solvent, recrystallized, and then the filtrate is filtered and dried to obtain the high-content antioxidant TMQ. The product has a dimer content of 50-60%, a trimer, tetramer and pentamer content of 80-90%, a primary amine content of 0-0.5%, and an isopropyl diphenylamine content of 0-0.3%. The invalid components (filtrate residue) of the ordinary TMQ are reused, and the method is suitable for industrial production of the high-content TMQ.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical technology and relates to a method for preparing a high-content antioxidant TMQ. Background Technology

[0002] 2,2,4-Trimethyl-1,2-dihydroquinoline is mainly used in the production of antioxidant TMQ. Antioxidant TMQ is a di, tri, and tetrapolymer of 2,2,4-trimethyl-1,2-dihydroquinoline, also known as antioxidant RD. It is a ketamine antioxidant, appearing as pale yellow to off-white granules or flakes. Primarily used as a rubber antioxidant, its annual domestic demand reaches 100,000 tons, making it one of the most in-demand rubber antioxidant products in both domestic and international markets.

[0003] The main raw materials for synthesizing antioxidant TMQ are aniline and acetone (or their derivatives). The process can be broadly divided into two types: a one-step method and a two-step method. The one-step process involves aniline and acetone undergoing condensation and polymerization under a catalyst to directly obtain a TMQ condensation solution containing di, tri, and tetrapolymers of 2,2,4-trimethyl-1,2-dihydroquinoline. The TMQ condensation solution is then neutralized with liquid alkali, dehydrated, and distilled to obtain TMQ. The two-step process involves aniline and acetone undergoing condensation under a catalyst. The reaction solution or the neutralized reaction solution is distilled or fractionally purified to obtain 2,2,4-trimethyl-1,2-dihydroquinoline, i.e., the TMQ monomer. The TMQ monomer then undergoes polymerization under a catalyst to obtain di, tri, and tetrapolymers of 2,2,4-trimethyl-1,2-dihydroquinoline. These are then neutralized, dehydrated, and distilled to obtain the antioxidant TMQ. Sometimes, to accelerate the reaction process, solvents such as toluene, xylene, and cyclohexane are added to the reaction. Therefore, TMQ synthesis methods can be divided into "solvent method" or "solvent-free method".

[0004] With the implementation of the new national standard GB / T8826-2019 for TMQ in China in 2020, TMQ is divided into ordinary type and high content type. The high content type of TMQ requires an effective body content of ≥70.0% and a primary amine content of ≤1.0%, while the ordinary type of TMQ requires an effective body content of ≥40.0% and no requirement for primary amine content. The high content type of TMQ is more environmentally friendly and has higher application efficiency, becoming the future trend of the TMQ industry.

[0005] CN103467372A describes a method for the combined production of TMQ and antioxidant FR: a catalyst is added to the fore-distillate during the distillation process of the finished TMQ product, followed by neutralization, washing with water, and distillation to obtain the finished antioxidant FR product. While this method can yield high-content TMQ, the yield is limited by the production of ordinary TMQ and its fore-distillate.

[0006] CN112142657A describes a method of reacting the forefraction and acetone with a catalyst to obtain a low-primary-amine TMQ reaction solution; neutralizing the low-primary-amine TMQ reaction solution with liquid alkali, separating water, and then distilling the oil phase to obtain the low-primary-amine TMQ. Although this method reduces the primary amine content, the effective content does not significantly increase to above 70%.

[0007] CN113402457A describes a method for preparing a high-efficiency antioxidant RD, including the following steps: (1) Synthesizing a composite oxide catalyst: Zirconium oxychloride and tetrabutyl titanate are dissolved in an alcohol-water mixed solvent, mixed evenly, acetic acid is added, stirred, and a solvothermal reaction is carried out in a reaction vessel. After the reaction is completed, the mixture is cooled to room temperature, filtered, washed, and dried to obtain zirconium-doped porous titanium dioxide particles; the zirconium-doped porous titanium dioxide particles are calcined at a certain temperature, cooled to room temperature after calcination, and the obtained calcined porous particles are impregnated with 15% amino acid. (1) Filter, wash and dry in sulfonic acid solution to obtain composite oxide catalyst; (2) Condensation Add part of the obtained composite oxide catalyst to aniline preheated to 30-40℃, add acetone, react at 80-90℃ for 0.5h to obtain condensation monomer; (3) Polymerization Mix the condensation monomer with another part of composite oxide catalyst evenly, react at 150-160℃ for 5-6h to obtain high-efficiency antioxidant RD, which can increase the content of effective polymer in antioxidant RD to more than 80%, of which the content of dimer is 50%-58%. Summary of the Invention

[0008] The purpose of this invention is to provide an improvement in the quality of existing conventional TMQ production processes, enabling the large-scale production of high-content antioxidant TMQ.

[0009] The general method for preparing rubber antioxidant TMQ is as follows: aniline is reacted by continuously introducing acetone under the action of a catalyst, with reaction water being removed during the reaction. After the reaction, liquid alkali is added for neutralization, adjusting to alkalinity, separating water, and distilling the oil phase to remove unreacted acetone, water, aniline, and the fore fraction, yielding TMQ. Taking hydrochloric acid catalyst as an example, the molar ratio of aniline, hydrochloric acid, and acetone is 1:(0.05~0.3):(1.5~10), the polycondensation reaction temperature is 90-180℃, and the reaction time is 1-10 hours. Currently, most production processes focus on ordinary TMQ, with a small amount obtaining high-content TMQ through a two-step method, but this inevitably results in the production of ordinary TMQ as well. For example, a TMQ plant built by a domestic company in Shandong has a high-content TMQ to ordinary TMQ production capacity ratio of 1:1.5.

[0010] This invention relates to a method for preparing high-content TMQ. The preparation method is achieved through the following steps:

[0011] ①For the common type of TMQ obtained by the general method of preparing antioxidant TMQ, a composite solvent is added, dissolved at a certain temperature, cooled, and filtered to obtain filtrate and filter residue;

[0012] ②The filtrate is desolventized to obtain high-content TMQ;

[0013] ③ Add catalyst to the filter residue and react with acetone to obtain ordinary TMQ;

[0014] ④ The ordinary TMQ set obtained in step ③ is used in step ①.

[0015] The composite solvent is one or more of cyclohexane, cycloheptane, cyclopentane, cyclooctane, and any of their chloro- or alkyl-substituted derivatives, mixed with water in a certain proportion. The water content is 3-20%.

[0016] Furthermore, the composite solvent is preferably a mixture of cycloheptane, cyclooctane, chlorocycloheptane and water, with the water content preferably being 10-12%.

[0017] The dissolution process involves a mass ratio of ordinary TMQ to the composite solvent of 1:(0.5~3).

[0018] To ensure complete dissolution, ordinary TMQ can be pulverized into fine particles or powder, generally to a mesh size of 5-50 or smaller, preferably below 10 mesh.

[0019] The dissolution process is carried out at a temperature of 50-150℃ for 1-10 hours. Alternatively, the dissolution temperature may be 70-100℃ for 3-5 hours.

[0020] The cooling refers to cooling the temperature above the melting point of the composite solvent, preferably 10-25°C.

[0021] The high-content TMQ has an active ingredient content (the sum of di, tri, and tetramers of 2,2,4-trimethyl-1,2-dihydroquinoline) of over 80% and a primary amine content of ≤1.0%.

[0022] The conventional TMQ obtained by the general method for preparing antioxidant TMQ has an active ingredient content (the sum of di, tri, and tetrapolymers of 2,2,4-trimethyl-1,2-dihydroquinoline) of 40-70% and a primary amine content of 1-20%.

[0023] The filter residue refers to the undissolved portion in step ①, with an effective content of 0-20%, and the remainder mainly consists of intermediates or impurities from the preparation process of ordinary TMQ.

[0024] The mass ratio of the high-content TMQ to the filter residue is 1:(0.6-2).

[0025] The filter residue is added to a catalyst and reacted with acetone. After the reaction, the reaction solution is neutralized, adjusted to alkalinity, water is separated, and the oil phase is distilled to obtain ordinary TMQ. The mass ratio of filter residue to acetone to catalyst is 1:(0.5~3):1:(0.01~0.3), the reaction temperature is 90-250℃, and the reaction time is 1-10 hours. The catalyst is a common catalyst for the preparation of TMQ, such as hydrochloric acid, sulfonic acid, p-toluenesulfonic acid, sulfuric acid, titanic acid, and titanate esters.

[0026] Furthermore, the mass ratio of acetone to catalyst in the filter residue is 1:(1~2):1:(0.05~0.1), the reaction temperature is 120-150℃, and the reaction time is 2-4 hours. Hydrochloric acid is preferred as the catalyst.

[0027] Using the method of this application, the high-content TMQ product can achieve a dimer content of 60-70%, a di, trimer, and tetramer content of 80-90%, a primary amine content of 0-0.5%, and an isopropyl diphenylamine content of 0-0.5%.

[0028] Beneficial effects

[0029] The process for preparing high-content TMQ using this invention involves solvent recrystallization of ordinary TMQ prepared by conventional processes to obtain high-content TMQ. Undissolved portions are further reacted, achieving the recycling of ineffective components. The resulting high-content TMQ exhibits a dimer content of 60-70%, a di, tri, and tetramer content of 80-90%, and a primary amine content of 0-0.5%. The dimer content, exhibiting the best anti-aging properties, reaches over 50%, significantly improving the performance of this TMQ. Detailed Implementation

[0030] To better understand the present invention, the following embodiments further illustrate its content. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0031] Example 1

[0032] 200g of ordinary TMQ (containing more than 45.2% di, tri, and tetramers, 8.0% primary amine, and pulverized to 20 mesh) and 300g of composite solvent (containing 75% cycloheptane, 10% cyclohexane, and 15% water) were added to a reactor. The mixture was stirred and heated to 105℃, then cooled to 15℃ and filtered to obtain 99.7g of filter residue. After drying the filtrate, 102.2g of high-content TMQ was obtained. The content of di, tri, and tetramers was 82.4%, the primary amine content was 0.5%, the isopropyl diphenylamine content was 0.1%, and the softening point was 84.1℃.

[0033] The filter residue was tested and found to contain 6.2% di, tri, and tetramers and 15.5% primary amine. 10g of 31% hydrochloric acid catalyst was added to the filter residue to remove moisture. The mixture was then reacted by adding 100g of acetone dropwise over 3 hours at 110℃. After neutralization with liquid alkali, the residue was separated from water, and the oil phase was distilled to obtain ordinary TMQ. The content of di, tri, and tetramers was tested at 55.8%, the primary amine content at 4.5%, and the softening point at 85.4℃. All indicators met national standards.

[0034] Example 2

[0035] The operation was the same as in Example 1, but the type of composite solvent was changed (containing 86% cyclooctane, 10% cyclohexane, and 4% water). The resulting high-content TMQ was 100.4 g, with a content of 81.0% of di, tri, and tetramers, 0.4% of primary amine, 0.1% of isopropyl diphenylamine, and a softening point of 84.0 °C.

[0036] Example 3

[0037] The experimental method of Example 1 was used. Under otherwise unchanged conditions, the quality of TMQ was examined by changing the raw material composition and dissolution / separation operating conditions. The results are shown in the table below.

[0038]

[0039] 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 solvent type and the catalyst, temperature / time, and different reaction methods, such as batch and continuous reactions. Any modifications, equivalent substitutions, improvements, etc. (such as the use of acetone derivatives) 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 preparing a high content antioxidant TMQ, characterized in that It comprises the following steps: ① Common TMQ is added into a composite solvent, dissolved, cooled, filtered to obtain filtrate and residue; ② The filtrate is removed to obtain high content TMQ; ③ The residue is added into a catalyst and continuously reacted with acetone to obtain common TMQ; ④ The common TMQ obtained in step ③ is used in step ①; the composite solvent is one or more of cyclohexane, cycloheptane, cyclooctane, chlorocyclohexane or chlorocyclooctane, which is mixed with water in a certain proportion to form a composite solvent, and the water content is 3-20%.

2. The method of claim 1, wherein: The mass ratio of the common TMQ to the composite solvent is 1: (0.5-3), the dissolving temperature is 50-150℃, and the time is 1-10 hours.

3. The method of claim 2, wherein: The dissolving temperature is 70-100℃, and the time is 3-5 hours.

4. The method of claim 1, wherein: The temperature is cooled to 10-25℃.

5. The method of claim 1, wherein: The high content TMQ has a content of the sum of di-, tri- and tetra-polymer of 2,2,4-trimethyl-1,2-dihydroquinoline of 80% or more, and a content of primary amine of 1.0% or less; the common TMQ has a content of the sum of di-, tri- and tetra-polymer of 2,2,4-trimethyl-1,2-dihydroquinoline of 40-70%, and a content of primary amine of 1-20%.

6. The method of claim 1, wherein: The residue has an effective component content of 0-20%, and the rest is mainly intermediate or impurity in the preparation process of common TMQ; the mass ratio of the high content TMQ to the residue is 1: (0.6-2).

7. The method of claim 1, wherein: The residue is added into a catalyst and continuously reacted with acetone, and then the reaction liquid is neutralized to alkaline, water is separated, and the oil phase is distilled to obtain common TMQ; the mass ratio of the residue to acetone to catalyst is 1: (0.5-3): 1: (0.01-0.3), the reaction temperature is 90-250℃, and the reaction time is 1-10 hours; The catalyst is a catalyst for preparing common TMQ from hydrochloric acid, sulfonic acid, p-toluenesulfonic acid, sulfuric acid, titanium acid and titanium ester.

8. The method of claim 7, wherein: The mass ratio of the residue to acetone to catalyst is 1: (1-2): 1: (0.05-0.1), the reaction temperature is 120-150℃, the reaction time is 2-4 hours, and the catalyst is hydrochloric acid.

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