Microchannel preparation method of antioxidant 168

Abstract

The invention belongs to the field of preparation of antioxidants, and particularly relates to a microchannel preparation method of an antioxidant 168, and the microchannel preparation method specifically comprises the following steps: (1) adding a raw material 2, 4-di-tert-butylphenol and a catalyst into a preheating kettle for melting; (2) after complete melting, pumping the mixture and phosphorus trichloride into a preheated microchannel reactor according to a certain volume flow ratio through different pipelines to carry out premixing reaction, entering a high-temperature tubular reactor after reacting for a period of time, and rapidly reacting under the action of high temperature and a catalyst; and (3) after the reaction in the tubular reactor is finished, putting the material into a vacuum kettle for rapid deacidification, and then carrying out alcohol washing, filtering and vacuum drying to obtain the antioxidant 168. According to the method provided by the invention, the high-purity antioxidant 168 product can be efficiently obtained, the reaction time is greatly shortened, meanwhile, no organic solvent is used, post-treatment steps are reduced, the cost is effectively reduced, and the method has a relatively great application prospect.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of antioxidant 168, and specifically relates to a microchannel preparation method of antioxidant 168. Background Art

[0002] Antioxidant 168, chemical name tris (2,4-di-tert-butylphenyl) phosphite, was first developed and produced by a Swiss company. It is an excellent phosphite auxiliary antioxidant, colorless and odorless, with high thermal stability and good hydrolysis resistance. It can effectively decompose the hydroperoxides produced in the processing of polymer materials, thereby playing an antioxidant role. It is often used in combination with hindered phenol main antioxidants and is widely used in polymer materials such as polyolefins, elastomers, adhesives, rubbers and engineering plastics.

[0003] At present, the annual demand for antioxidant 168 has reached tens of thousands of tons. The domestic method is still batch production in the autoclave, which mainly has the problems of low production efficiency and unstable product quality. In addition, in the autoclave production process, HCl is usually discharged by blowing nitrogen and pumping negative pressure. In the presence of solvent, in order to achieve a higher yield, it often takes a long time to discharge HCl, which increases energy consumption costs. Patent CN115819451A adopts an autoclave continuous method to synthesize antioxidant 168. The advantage of this process is that the raw materials react continuously in the scraper film reactor in the continuous reactor, and the continuously generated HCl is discharged from the gas phase outlet of the scraper film reactor, which can significantly reduce the energy consumption of recovering triethylamine. However, its process is relatively complicated, and organic solvents are used in the synthesis process, which increases the post-processing cost.

[0004] The purpose of the present invention is to provide a microchannel preparation method for antioxidant 168. In order to solve the problems existing in the above-mentioned prior art, the present invention adopts a microchannel plus tubular reactor method to synthesize antioxidant 168, and at the same time achieves the following effects: 1. The microchannel is used in the synthesis process, which has the characteristics of good mixing effect and fast reaction rate. 2. No organic solvent is used in the synthesis process. Compared with the method with solvent, there is no need to consider the removal of solvent and the application of solvent, which reduces the production cost and has a great application prospect. Summary of the invention

[0005] To achieve the above object, the present invention provides the following solutions: The object of the present invention is to provide a microchannel preparation method of antioxidant 168, comprising the following steps: 1) heating the raw materials 2,4-di-tert-butylphenol and the catalyst to a molten state; 2) The molten 2,4-di-tert-butylphenol raw material and phosphorus trichloride are pumped into a preheated microchannel reactor through different pipelines for premixing reaction, and then pumped into a tubular reactor after a period of reaction to react rapidly under high temperature conditions; 3) After the reaction is completed, the material is vacuum deacidified, washed with alcohol, filtered, and vacuum dried to obtain antioxidant 168.

[0006] The catalyst is selected from any one of triethylamine, DMAP, DMF and pyridine.

[0007] The equivalent ratio of 2,4-di-tert-butylphenol, triethylamine and phosphorus trichloride is 3-3.5eq:0.01-0.2eq:1; more preferably, the equivalent ratio of 2,4-di-tert-butylphenol, triethylamine and phosphorus trichloride is 3.05-3.3eq:0.01-0.05eq:1.

[0008] The melting temperature in step (1) is ≥65°C, and the preheating temperature of the microchannel reactor in step (2) is 65-74°C.

[0009] The flow ratio of the molten 2,4-di-tert-butylphenol raw material and phosphorus trichloride pumped into the microchannel reactor is 8.1-8.8:1.

[0010] The residence reaction time in the microchannel reactor is 5-10 minutes.

[0011] In step (2), after the premixing reaction, the premixed material is introduced into a tubular reactor before solidification. The temperature in the tubular reactor is pre-controlled to be 190-200° C. so that the reaction system is kept in a liquid phase under high temperature conditions.

[0012] The catalytic reaction time in the tubular reactor is 5-10 minutes.

[0013] In the technical solution of the present invention, the antioxidant 168 is synthesized by a method combining a microchannel and a tubular reactor, so that the material can be kept in a liquid state during the reaction process, so that the system can react quickly without adding an organic solvent. At the same time, the generated hydrogen chloride has a very low solubility in the system, and can also achieve a rapid deacidification effect.

[0014] In the preferred technical scheme of the present invention, the method of keeping the system in a liquid phase state is that the materials are fully mixed and pre-reacted in a preheated microchannel reactor, and then enter a high-temperature tubular reactor before solidification. Under high temperature conditions, the materials can react rapidly while maintaining a liquid phase. If the temperature is not high enough, products will precipitate and block the tubular reactor.

[0015] In the preferred technical solution of the present invention, the premixing temperature of the microchannel reactor is lower than the boiling point of phosphorus trichloride. Too high a temperature may cause part of the phosphorus trichloride to overflow, thereby reducing the yield.

[0016] The model of the microchannel reactor used in the present invention is Corning G1-5FM Glass high-throughput microchannel reactor.

[0017] Preferably, the alcohol washing in step 3) is washing with methanol 2-4 times.

[0018] The technical solution of the present invention has the following advantages: The reaction process of the present invention is carried out in a microchannel, the materials are evenly mixed, and the esterification reaction can be carried out quickly under the conditions of catalyst and rapid entry into high temperature, and a high-purity antioxidant 168 product can be efficiently obtained. In addition, no solvent is used in the reaction process, and the separation and application of the solvent in the later stage are not involved, which effectively reduces energy consumption and has the advantages of simple operation, high production efficiency and low production cost. DETAILED DESCRIPTION

[0019] The following is a more detailed description of the microchannel preparation method of an antioxidant 168 of the present invention in combination with specific embodiments. Example 1 This embodiment provides a microchannel preparation method of an antioxidant 168, comprising the following steps: Before feeding, 733 g of 2,4-di-tert-butylphenol and 1.2 g of triethylamine were added to a 70° C. preheated kettle for melting. After 2,4-di-tert-butylphenol was completely melted, it was pumped into a 70° C. microchannel reactor together with 160 g of phosphorus trichloride through different pipelines for premixing reaction. The volume flow rate of 2,4-di-tert-butylphenol pumped in was 165.5 ml / min, and the volume flow rate of phosphorus trichloride pumped in was 20.3 ml / min. In this stage, the reaction mainly generated monoesters and diesters. The premixing reaction time (residence time) in the microchannel was 5 min. After the premixing reaction, the premixed materials entered the tubular reactor before solidification. The temperature in the tubular reactor was preset to 190° C. Under the action of high temperature and catalyst, the reaction occurred rapidly. The reaction time in the control tube was controlled to be 5 min. In this stage, triesters, i.e., the target product antioxidant 168, were mainly generated. The equivalent ratio of triethylamine to phosphorus trichloride is 0.01eq, and the equivalent ratio of 2,4-di-tert-butylphenol to phosphorus trichloride is 3.05eq. The volume flow rate of 2,4-di-tert-butylphenol and catalyst pumped into the microchannel is controlled to be 8.1 times the volume flow rate of phosphorus trichloride pumped into the microchannel. After the reaction is completed, it is placed in a vacuum kettle for deacidification. After the deacidification is completed, it is washed with alcohol 4 times, filtered, and vacuum dried at 50°C to obtain 727g of the target product, antioxidant 168, which is a white crystalline solid with a yield of 96.5%, an acid value of 0.11, and a purity of 99.85%.

[0020] Example 2 This embodiment provides a microchannel preparation method of an antioxidant 168, comprising the following steps: Before feeding, 769 g of 2,4-di-tert-butylphenol and 2.4 g of triethylamine were added to a 70°C preheating kettle for melting. After the 2,4-di-tert-butylphenol was completely melted, it was pumped into a 70°C microchannel reactor together with 160 g of phosphorus trichloride through different pipelines for premixing reaction. The volume flow rate of 2,4-di-tert-butylphenol pumped in was 173.9 ml / min, and the volume flow rate of phosphorus trichloride pumped in was 20.4 ml / min. In this stage, the reaction mainly generated monoesters and diesters. The premixing reaction time (residence time) in the microchannel was 5 min. After the premixing reaction, the premixed materials entered the tubular reactor before solidification. The temperature in the tubular reactor was preset to 190°C. Under the action of high temperature and catalyst, the reaction occurred rapidly. The reaction time in the control tube was 6 min. In this stage, triesters, i.e., the target product antioxidant 168, were mainly generated. The equivalent ratio of triethylamine to phosphorus trichloride is 0.02eq, and the equivalent ratio of 2,4-di-tert-butylphenol to phosphorus trichloride is 3.2eq. The volume flow rate of 2,4-di-tert-butylphenol and catalyst pumped into the microchannel is controlled to be 8.5 times the volume flow rate of phosphorus trichloride pumped into the microchannel. After the reaction is completed, it is placed in a vacuum kettle for deacidification. After the deacidification is completed, it is washed with alcohol 4 times, filtered, and vacuum dried at 50°C to obtain 730g of the target product, antioxidant 168, which is a white crystalline solid with a yield of 96.9%, an acid value of 0.13, and a purity of 99.78%.

[0021] Example 3 This embodiment provides a microchannel preparation method of an antioxidant 168, comprising the following steps: Before feeding, 7693g of 2,4-di-tert-butylphenol and 24g of triethylamine were added to a 70°C preheating kettle for melting. After the 2,4-di-tert-butylphenol was completely melted, it was pumped into a 70°C microchannel reactor together with 1600g of phosphorus trichloride through different pipelines for premixing reaction. The volume flow rate of 2,4-di-tert-butylphenol pumped in was 1087.5ml / min, and the volume flow rate of phosphorus trichloride pumped in was 127.1ml / min. In this stage, the reaction mainly generated monoesters and diesters. The premixing reaction time (residence time) in the microchannel was 8min. After the premixing reaction, the premixed materials entered into a high-temperature tubular reactor before solidification. The temperature in the tubular reactor was preset to 190°C. Under the action of high temperature and catalyst, the reaction occurred rapidly. The reaction time in the control tube was 8min. In this stage, triesters, i.e., the target product antioxidant 168, were mainly generated. The equivalent ratio of triethylamine to phosphorus trichloride is 0.02eq, and the equivalent ratio of 2,4-di-tert-butylphenol to phosphorus trichloride is 3.2eq. The volume flow rate of 2,4-di-tert-butylphenol and catalyst pumped into the microchannel is controlled to be 8.5 times the volume flow rate of phosphorus trichloride pumped into the microchannel. After the reaction is completed, it is placed in a vacuum kettle for deacidification. After the deacidification is completed, it is washed with alcohol 4 times, filtered, and dried in vacuum at 50°C to obtain 7357g of the target product, antioxidant 168, which is a white crystalline solid with a yield of 97.6%, an acid value of 0.09, and a purity of 99.91%.

[0022] Example 4 This embodiment provides a microchannel preparation method of an antioxidant 168, comprising the following steps: Before feeding, 7932g of 2,4-di-tert-butylphenol and 24g of triethylamine were added to a 70°C preheating kettle for melting. After the 2,4-di-tert-butylphenol was completely melted, it was pumped into a 70°C microchannel reactor together with 1600g of phosphorus trichloride through different pipelines for premixing reaction. The volume flow rate of 2,4-di-tert-butylphenol pumped in was 896.9ml / min, and the volume flow rate of phosphorus trichloride pumped in was 101.7ml / min. In this stage, the reaction mainly generated monoesters and diesters. The premixing reaction time (residence time) in the microchannel was 10min. After the premixing reaction, the premixed materials entered into a high-temperature tubular reactor before solidification. The temperature in the tubular reactor was preset to 200°C. Under the action of high temperature and catalyst, the reaction occurred rapidly. The reaction time in the control tube was 10min. In this stage, triesters, i.e., the target product antioxidant 168, were mainly generated. The equivalent ratio of triethylamine to phosphorus trichloride is 0.03eq, and the equivalent ratio of 2,4-di-tert-butylphenol to phosphorus trichloride is 3.3eq. The volume flow rate of 2,4-di-tert-butylphenol and catalyst pumped into the microchannel is controlled to be 8.8 times the volume flow rate of phosphorus trichloride pumped into the microchannel. After the reaction is completed, it is placed in a vacuum kettle for deacidification. After the deacidification is completed, it is washed with alcohol 4 times, filtered, and vacuum dried at 50°C to obtain 7402g of the target product, antioxidant 168, which is a white crystalline solid, with a yield of 98.2%, an acid value of 0.18, and a purity of 99.84%.

[0023] Comparative Example 1 The method and steps are the same as those in Example 1, except that the premixing temperature in the microchannel is increased from 70°C to 90°C, and vacuum drying is performed at 50°C to obtain 677.0 g of the target product, antioxidant 168, which is a white crystalline solid. The yield is 89.8%, the acid value is 0.2, and the purity is 99.41%.

[0024] Meanwhile, all contents not described in detail in this specification belong to the prior art known to those skilled in the art. The above embodiments are only preferred technical solutions of the present invention and are not to be regarded as limitations of the present invention. Although the embodiments of the present invention have been shown and described, it is understood by those skilled in the art that various changes, modifications, substitutions and deformations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microchannel preparation method of antioxidant 168, characterized in that: The following steps are involved: (1) heating the raw materials 2,4-di-tert-butylphenol and the catalyst to a molten state; (2) The molten 2,4-di-tert-butylphenol raw material and phosphorus trichloride are pumped into a preheated microchannel reactor through different pipelines for premixing reaction. After a period of reaction, the mixture is then put into a tubular reactor to react rapidly under high temperature conditions. (3) After the reaction is completed, the material is vacuum deacidified, washed with alcohol, filtered, and vacuum dried to obtain antioxidant 168.

2. A microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: The catalyst is selected from any one of triethylamine, DMAP, DMF and pyridine.

3. A microchannel preparation method of an antioxidant 168 according to claim 2, characterized in that: The equivalent ratio of 2,4-di-tert-butylphenol, triethylamine and phosphorus trichloride is 3-3.5eq:0.01-0.2eq:1; more preferably, the equivalent ratio of 2,4-di-tert-butylphenol, triethylamine and phosphorus trichloride is 3.05-3.3eq:0.01-0.05eq:

1.

4. The microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: The melting temperature in step (1) is ≥ 65°C, and the preheating temperature of the microchannel reactor in step (2) is 65-74°C.

5. The microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: The volume flow ratio of the molten 2,4-di-tert-butylphenol raw material and phosphorus trichloride pumped into the microchannel reactor is 8.1-8.8:

1.

6. A microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: The residence reaction time in the microchannel reactor is 5-10 minutes.

7. A microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: In step (2), after the premixing reaction, the premixed material is introduced into a tubular reactor before solidification. The temperature in the tubular reactor is pre-controlled to be 190-200° C. so that the reaction system is kept in a liquid phase under high temperature conditions.

8. The microchannel preparation method of an antioxidant 168 according to claim 1, characterized in that: The catalytic reaction time in the tubular reactor is 5-10 minutes.