WO2023056739A1

WO2023056739A1 - Production process for accelerator dcbs

Info

Publication number: WO2023056739A1
Application number: PCT/CN2022/087695
Authority: WO
Inventors: 孟庆森; 赵玉军; 陆平; 回俊博; 孔令鑫; 黄汇江
Original assignee: 科迈化工股份有限公司
Priority date: 2021-10-08
Filing date: 2022-04-19
Publication date: 2023-04-13
Also published as: CN113582944A; CN113582944B

Abstract

The present invention belongs to the field of heterocyclic compounds, and specifically relates to a production process for accelerator DCBS. The production process comprises the following steps: 1) mixing MBTS and a mixed solvent under a stirring condition until uniform to obtain a raw material slurry; 2) adding the mixed raw material slurry and a catalyst to an oxidation reactor for oxidation; and 3) acquiring the target product DCBS after the reaction is finished. In the present invention, MBTS is used as a main raw material, such that the reaction process of directly oxidizing an MBT-dicyclohexylamine complex is avoided to a great extent, and further, the reaction yield is greatly improved. Moreover, the process is relatively simple, and the industrialization transformation thereof is relatively easy.

Description

Production process of accelerator DCBS

technical field

The invention belongs to the field of heterocyclic compounds, and in particular relates to a production process of accelerator DCBS.

Background technique

Accelerator DCBS (Chinese name N, N-dicyclohexyl-2-benzothiazole sulfenamide) is an aftereffect accelerator, which has good dispersion performance in rubber, long burning time in rubber, and high operating safety , with vulcanization acceleration and adhesion, suitable for high-activity reinforcing materials, especially for radial tires. Therefore, with the increase of tire output and tire radialization rate, the consumption of accelerators CBS, TBBS and DCBS has increased significantly in recent years. According to the statistics of China Rubber Industry Association, the total output of accelerators in my country was 375,000 tons in 2014, among which the slow-acting sulfenamide accelerators represented by CBS, TBBS and DCBS accounted for 42.51% of accelerator output.

The current industrialization method of the rubber vulcanization accelerator DCBS is to use sodium hypochlorite as an oxidant to oxidize the sodium salt of the raw material MBT and dicyclohexylamine to generate the accelerator DCBS. However, the process yield is low (the selectivity of the raw material MBT is not more than 80%), and the amount of waste water produced is large. 1 ton of product produces about 8-10 tons of waste water, and the salt content is high, and the COD is high (generally above 30000ppm) , difficult to biochemical treatment (there is biological toxicity), unfavorable to environmental protection.

In 2018, a breakthrough was made in the microchannel synthesis process of the accelerator DCBS. The inventor used the microchannel reactor as the main synthesis equipment, dissolved the raw material MBT in the sodium hydroxide solution, and prepared the M-Na salt solution, then used sodium hypochlorite, hydrogen peroxide Or oxygen as oxidant, M-Na salt solution, dicyclohexylamine, hydrochloric acid as raw materials, continuous synthesis accelerator DCBS. Compared with the traditional tank-type batch process, this process has the advantages of high reaction yield (the highest can be more than 96%), low COD of wastewater (the lowest COD can be within 8000ppm), and easy treatment. However, not only a large amount of lye and hydrochloric acid need to be introduced during the synthesis process, but also a large amount of lye and chlorine gas are consumed in the preparation of raw material sodium hypochlorite, so that a large amount of salt remains in the waste water produced by this technology, and the amount of by-product sodium chloride is about It is about 50% of the output of DCBS. Although a large amount of by-product sodium chloride has relatively clear sales channels, its added value is too low, which is still a problem that many DCBS manufacturers are more distressed. If it can be reduced in the process, Or avoiding the generation of sodium chloride can not only reduce the consumption of raw materials acid, alkali and chlorine, but also increase the profit margin of products and improve the core competitiveness of production enterprises.

In 2019, the inventor used a microchannel reactor as the main synthesis equipment and chlorine gas as the oxidant to continuously synthesize the accelerator DCBS. Compared with the first-generation DCBS microchannel synthesis technology, this technology further improves the utilization rate of raw materials and reduces many dangerous links in the actual production process. But it is undeniable that this process still produces a relatively large amount of by-product sodium chloride, and in the current social environment, the treatment of this part of sodium chloride is still a big problem.

In addition to the above-mentioned technologies, a foreign patent proposed a new synthesis scheme in the 1990s, and its synthesis route is as follows:

1. Reaction of dicyclohexylamine and sodium hypochlorite to prepare chlorinated dicyclohexylamine.

2. After mixing chlorinated dicyclohexylamine, dicyclohexylamine and MBTS, use ammonia gas or sodium methoxide as an acid-binding agent and anhydrous methanol as a solvent to prepare accelerator DCBS in one step.

Compared with the direct oxidation preparation of sodium hypochlorite, this process has the advantage that the conversion rate of raw material MBTS is extremely high, generally exceeding 98%, and there is basically no side reaction. However, the process still cannot avoid the use of sodium hypochlorite, which will inevitably produce sodium chloride-containing brine. In addition, if the process uses ammonia as the acid-binding agent, ammonium chloride will be produced as a by-product, and if sodium methoxide is used as the acid-binding agent, sodium chloride will be produced as a by-product; and these by-product salts are mixed with the product DCBS Together, they need to be separated by washing with hot water, and saline wastewater will also be produced here. In addition, the process uses anhydrous methanol as a solvent, and its recyclability is low, which is also a major problem hindering the industrialization of this process.

To sum up, the currently commonly reported DCBS synthesis technology cannot effectively avoid the generation of the three wastes, and the generated "three wastes" also have the problems of difficulty in processing and high processing costs. It is necessary to develop a new DCBS synthesis process to solve or alleviate the above problems.

Contents of the invention

The purpose of the present invention is to overcome the shortcoming in the prior art, provide a kind of production technology of accelerator DCBS.

To achieve the above object, the technical solution adopted in the present invention is:

A kind of production technique of promotor DCBS, comprises the steps:

1) Mixing MBTS and a mixed solvent uniformly under stirring conditions to obtain a raw material slurry; the mixed solvent is a mixture of isopropanol, water and toluene.

2) Put the mixed raw material slurry and catalyst into the oxidation kettle, start the stirring, turn on the dicyclohexylamine feed pump to slowly pump it into the kettle, and at the same time feed oxygen to start the oxidation reaction, control the reaction pressure during the reaction, when After the quality of passing oxygen reaches the requirement, it is considered that the reaction has reached the end point, and the time of adding dicyclohexylamine is controlled to be shorter than the time of passing oxygen during the reaction; the catalyst is a cationic resin with a sulfonic acid group (-SO ₃ H) Mixture with anionic resins with tertiary amino groups (-NR ₂ ).

3) After the reaction is completed, filter the catalyst in the system to obtain the product solution. After standing still for phase separation, the upper oil phase undergoes cooling and crystallization, and after filtration, the target product DCBS can be obtained after washing with water.

The mass ratio of isopropanol, water and toluene in step 1) is 1:2-4:3-6.

The mass ratio of MBTS to the catalyst in the raw material slurry in step 2) is 1:0.5-0.8; the mass ratio of the cationic resin with sulfonic acid groups (-SO ₃ H) to the anionic resin with tertiary amino groups (-NR ₂ ) in the catalyst It is 1:0.3-0.5.

The ratio of MBTS to the mixed solvent in step 1) is 1:5-7.

The reaction temperature in step 2) is 40-70°C; the pressure in the reactor is controlled at 0.3-1.0Mpa.

In step 2), the mass ratio of MBTS in the raw material slurry to oxygen is 1:0.1-0.15, and the oxygen feeding time is controlled at 4.5-6h.

The product solution in step 3) is allowed to stand still for 1-1.5 hours for phase separation; the crystallization temperature of the upper oil phase is cooled to 0-5°C.

Compared with prior art, the beneficial effect of the present invention is:

First of all, this technology uses oxygen as the oxidant to avoid the generation of waste salt, solve the problem of difficult treatment of NaCl-containing high COD wastewater in the traditional process, and the difficulty of further application of waste salt, solve environmental problems, and avoid waste of resources.

Secondly, the technology uses an anion-cation composite macroporous resin solid catalyst, which has high selectivity, and the yield of the final product DCBS is above 95% (calculated in terms of pure raw material MBTS). The reasons are as follows:

1) Due to the weak activity of dicyclohexylamine, it cannot directly react with MBTS, so a strong acidic cationic resin is introduced to activate dicyclohexylamine so that it can react with MBTS to generate DCBS and the intermediate product MBT.

2) Due to the complexation of MBT and dicyclohexylamine formed in the first step reaction [MBT-dicyclohexylamine salt] has poor solubility and is difficult to dissolve through a solvent, which makes it exist in the form of solid particles In the reaction system, it is also difficult to be further oxidized into DCBS after contacting with catalyst and oxygen. Therefore, the reaction process cannot directly mix MBTS, dicyclohexylamine, solvent and catalyst and then feed oxygen into the reaction system. It is necessary to drop dicyclohexylamine into the mixed reaction system. With the addition of dicyclohexylamine, the Under the catalysis of acidic resin, the reaction gradually produces DCBS and MBT. At this time, a weakly basic resin catalyst with a tertiary amino group (-NR2) structure is introduced. Under the action of the catalyst, the MBT produced by the reaction is oxidized to MBTS, and then formed as follows: The reaction microcirculation is shown in Figure 1.

Furthermore, this technology uses isopropanol/water/toluene ternary mixed solution as solvent, which effectively realizes the separation of main product and by-product, and then effectively improves the purity of the product DCBS to more than 99%. In the ternary mixture solvent, each component plays a different role.

1), the effect of toluene is mainly the solvent of product solvent and part oil-soluble impurity. During the reaction process, toluene can effectively dissolve the product DCBS, and then effectively separate the unreacted raw material MBTS from the product. Secondly, because the catalyst is an ionic resin, the oxidation reaction mainly occurs in the water phase, and toluene, as the main component of the oil phase, can effectively separate the catalyst from the product, reduce the deep oxidation of the product CBS to form other by-products, and increase the yield of the product. Furthermore, toluene can be used as a solvent for oil-soluble impurities in the raw material MBTS, reducing its interference with the oxidation reaction carried out in the water phase, and further improving the reaction yield. The solubility of the final product DCBS in toluene varies greatly with temperature fluctuations, and it is easy to separate by crystallization.

In addition, in the traditional process, isopropanol is mainly relied on to complete the effect of the above toluene, but the biggest difference between this technology and the traditional technology is that oxygen is used as the oxidant, and no brine is produced during the reaction process, and the function of a small amount of water in the system is mainly for The catalyst provides an activation environment. If there is a large amount of isopropanol in the system, the entire reaction system will appear homogeneous due to solubility problems, and thus cannot effectively protect the product.

2) The function of water is mainly to provide active ions for the catalyst. Since the catalyst is an ionic resin, it needs the presence of water to be effectively activated.

3), the role of a small amount of isopropanol in the system is as a solvent for the MBT-dicyclohexylamine complex, so that it can slowly participate in the oxidation process, and then generate DCBS and other oxidation products. Since the MBT-dicyclohexylamine complex needs certain conditions before it can be converted into DCBS, in the traditional process, the pH of the system needs to be stable above 10 and the system is in a peroxidized state before it can be converted into DCBS. Therefore, the selectivity of this part of the reaction is not high, which is also the main reason why the yield of DCBS in this technology can only be controlled at 95%. But if there is no isopropanol in the system, then the MBT-dicyclohexylamine complex generated in the reaction process directly exists in the system in solid form, and finally separates the system together with the product DCBS, due to the solubility of the complex Poor, so the cost of separating it from DCBS is relatively high, which is not conducive to the industrial transformation of technology.

Finally, the technology uses MBTS as the raw material instead of MBT for the reason.

The core innovation of this technology is to rely on the microcirculation in the reaction process shown in Figure 1 to achieve high DCBS selectivity and yield. Namely: at first, by acidic catalyst activation dicyclohexylamine and MBTS reaction generate DCBS and free MBT; Secondly, catalyze free MBT and oxygen reaction by basic resin and generate MBTS and then react with dicyclohexylamine.

This is also the feature that the present invention is different from traditional technology, because traditional technique all adopts MBT and dicyclohexylamine as raw material, at first produces the complexation of MBT-dicyclohexylamine by MBT-Na salt solution and dicyclohexylamine, hydrochloric acid reaction Then use sodium hypochlorite to oxidize the complex to generate product DCBS. Because this complex, the final product DCBS all can be suspended in the reaction system with solid form, so introduce this water-soluble solvent of isopropanol to increase the dissolubility of reaction intermediate product in water, and then make part intermediate product and oxidant sodium hypochlorite in water The reaction in the phase changes from a heterogeneous reaction to a homogeneous reaction, thereby increasing the reaction speed and reaction yield, and reducing the side reactions caused by deep oxidation during the long-term contact between sodium hypochlorite and solid-phase intermediate products. However, the introduction of isopropanol solvent can only partially increase the reaction rate, and cannot essentially solve the process of preparing DCBS as a heterogeneous reaction. Therefore, most industrialization implementations have found that after the industrialization of this technology, the conversion rate of the raw material MBT is basically below 80%, or even lower.

However, the present invention adopts MBTS as the main raw material, avoids the reaction process of directly oxidizing the MBT-dicyclohexylamine complex to a large extent, and then greatly improves the yield of the reaction, and the process is relatively simple, and industrial transformation is also relatively easy .

Description of drawings

Figure 1 is a schematic diagram of the cycle in which MBT reacts with oxygen to generate MBTS and then reacts with dicyclohexylamine.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below in conjunction with examples.

Embodiment 1: a kind of technique of MBTS oxygen oxidation synthesis promotor DCBS, comprises the steps:

(1) At 20°C, mix MBTS with a mass ratio of 1:5 and a mixed solvent for 0.3 h under stirring. The mixed solvent is a mixture of isopropanol, water and toluene, and the solvent is isopropanol: water: Toluene=1:2:3. After the mixing is completed, it is the raw material slurry.

(2) After putting the raw material slurry into the autoclave, add a macroporous resin catalyst with a mass of 0.5 times the mass of MBTS. After starting the stirring, turn on the dicyclohexylamine feed pump and start to feed oxygen to start the oxidation reaction. The catalyst is mixed with cationic resin and anionic resin (the cationic resin is cationic resin with sulfonic acid group (-SO ₃ H), Xi’an Lanxiao LXC501; the anionic resin is anionic resin with tertiary amino group (-NR ₂ ), Xi’an Lanxiao D301), the mass ratio of the two is 1:0.3. During the process, the reaction temperature was controlled at 40° C., the reaction pressure was 0.3 Mpa, and the oxygen gas was introduced for 6 hours.

(3) When the quality of the pumped dicyclohexylamine reaches 1.03 times the mass of MBTS in the raw material slurry, stop the dicyclohexylamine feeding pump. At this time, after continuing to feed oxygen for 20 minutes, the total mass of fed oxygen reaches 0.1 times of the mass of the input MBTS, stop feeding oxygen, and the reaction ends.

(4) After the reaction is completed, the catalyst is recovered by filtration, the filtrate is allowed to stand for 1 h, and the phases are separated. The aqueous solution of the lower layer is applied to the synthesis process of the next batch, and the remaining small amount is recovered through normal pressure distillation to recover isopropanol and toluene. The temperature of the upper oil phase was lowered to 5°C for crystallization, and the wet material obtained after filtration was washed with water to obtain the target product DCBS.

For accurate measurement yield, after reaction mother liquor (oil phase, water phase are applied mechanically) once, weigh after material drying, the yield of DCBS product is 95.8% (by raw material MBTS mass meter), the purity of DCBS product is 99.3% %, the appearance is light pink crystalline powder.

Table 1 shows the influence of different parameters on the results.

As shown in Example 3, since the reaction temperature is too high, oxygen can deeply oxidize the product DCBS to other products, so the reaction yield decreases and the product purity is poor. In addition, this technology controls the overall oxygen intake in the oxidation process, and high-temperature deep oxidation will consume excess oxygen, so that not only peroxidation by-products are produced during the reaction process, but also the raw material MBTS is unreacted. After detection and analysis, the yield of the product DCBS is only 49.9%, and the purity is 76.7%.

Table 1

Example 4 shows that due to the removal of the isopropanol component in the solvent, MBT-dicyclohexylamine exists in the system in solid form in the reaction, and it is difficult to oxidize to generate DCBS, so that the reaction yield is reduced, and the product purity is reduced . After detection and analysis, the yield of the product DCBS is only 88.0%, and the purity is 89.8%.

Example 5 shows that due to the lack of core component anion resin in the catalyst, the microcirculation of the reaction can only be completed halfway, that is, the reaction of MBTS and dicyclohexylamine to generate DCBS and MBT, and the MBT produced will be complexed in the system. dicyclohexylamine, which hinders the reaction. After detection and analysis, the yield of the product DCBS is only 35.6%, and the purity is 55.8%.

Example 6 shows that due to the excessive amount of dicyclohexylamine dropped into the system, the amount of complexation between MBT and dicyclohexylamine in the reaction microcirculation is too large, resulting in a low yield. And dicyclohexylamine is also a solvent for the product DCBS, excessive input will cause incomplete crystallization, further affecting the yield.

Example 7 shows that due to the lack of water in the solvent, the catalyst cannot be effectively activated, and the catalytic efficiency is extremely low. Only a part of MBTS reacts with dicyclohexylamine within the reaction time to form the target product DCBS. And due to the existence of oxygen in the reaction system, there are certain oxidation side reactions in the system, which affects the purity of the product, and because the product is difficult to completely separate from the raw material MBTS, the purity of the product is extremely low. After detection and analysis, the yield of the product DCBS is only 26.7%, and the purity is 39.6%.

Example 8 shows that due to the lack of toluene in the solvent, the solvent is homogeneous, and part of the product DCBS is deeply oxidized into other by-products during the oxidation process, resulting in insufficient yield of the final product. After detection and analysis, the yield of the product DCBS was 89.3%, and the purity was 98.3%.

Example 9 shows that due to the lack of the core component cationic resin in the catalyst, the reaction microcirculation cannot be effectively started, that is, MBTS cannot effectively react with dicyclohexylamine to generate DCBS and MBT, resulting in extremely low reaction yield. And because the product is difficult to completely separate from the raw material MBTS, the purity of the product is extremely low. After detection and analysis, the yield of the product DCBS is only 16.6%, and the purity is 21.2%.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims

A kind of production technique of promotor DCBS is characterized in that, comprises the following steps:

1) Mix MBTS and a mixed solvent evenly under stirring conditions to obtain a raw material slurry; the mixed solvent is a mixture of isopropanol, water and toluene; the mass ratio of isopropanol, water and toluene is 1:2-4 :3-6; The ratio of MBTS to mixed solvent is 1:5-7;

2) Put the mixed raw material slurry and catalyst into the oxidation kettle, start the stirring, turn on the dicyclohexylamine feed pump to slowly pump it into the kettle, and at the same time feed oxygen to start the oxidation reaction, control the reaction pressure during the reaction, when The reaction is considered to have reached the end point when the quality of the oxygen introduced meets the requirements. The quality of the oxygen introduced meets the requirements specifically: the mass ratio of MBTS in the raw material slurry to the oxygen introduced is 1:0.1-0.15, and the oxygen feeding time is controlled at 4.5- 6h;

In the reaction process, the dropping time of dicyclohexylamine is controlled to be shorter than the oxygen passing time;

The catalyst is a mixture of cationic resins with sulfonic acid groups and anionic resins with tertiary amino groups; the mass ratio of the cationic resins with sulfonic acid groups to the anionic resins with tertiary amino groups in the catalyst is 1:0.3-0.5;

The mass ratio of MBTS to catalyst in the raw material slurry is 1:0.5-0.8; the reaction temperature is 40-70°C; the pressure inside the reactor is controlled at 0.3-1.0Mpa;

3) After the reaction is completed, filter the catalyst in the system to obtain the product solution. After standing still for phase separation, the upper oil phase undergoes cooling and crystallization, and after filtration, the target product DCBS can be obtained after washing with water.
The production process of accelerator DCBS according to claim 1, characterized in that, in step 3), the product solution is left to stand for phase separation for 1-1.5 hours; the crystallization temperature of the upper oil phase is 0-5 ° C.