A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor

Abstract

This invention provides a method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor. The method includes the following steps: 1,3-dicyclohexylcarbodiimide and a catalyst are mixed uniformly and preheated to obtain a premix; a chloroform solution of p-benzoquinone dioxime, a chloroform solution of benzoic acid, and the premix are simultaneously introduced into the microchannel reactor for reaction; the resulting reaction solution is subjected to vacuum distillation, washing, filtration, and drying to obtain dibenzoyl-p-benzoquinone dioxime. The synthesis method of this invention features high reaction conversion rate, high production efficiency, few side reactions, and high safety. The obtained dibenzoyl-p-benzoquinone dioxime product has stable quality. Furthermore, the organic solvent used can be recovered and reused after vacuum distillation, overcoming the problems of inaccurate temperature control, poor safety, numerous side reactions, and difficult waste treatment in traditional processes. This provides a new approach for the synthesis of dibenzoyl-p-benzoquinone dioxime.

Description

Technical Field

[0001] This invention belongs to the field of synthesis and preparation technology of dibenzoyl-p-benzoquinone dioxime, specifically relating to a method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor. Background Technology

[0002] Benzoyl-p-benzoquinone dioxime is a high-performance rubber vulcanizing agent commonly used in butyl rubber, natural rubber, and styrene-butadiene rubber. Its properties are similar to p-benzoquinone dioxime, but due to the presence of a benzoyl group in its structure, it exhibits stronger vulcanization retardation and better scorch resistance. During vulcanization, diphenylpropizoazole disulfide is typically used as an accelerator in the vulcanization system, resulting in faster vulcanization, better aging resistance of the rubber, and improved heat resistance and ozone resistance of rubber products. Furthermore, benzoyl-p-benzoquinone dioxime can also be used as a highly effective vulcanization accelerator in peroxide vulcanization, offering rapid vulcanization and high elongation. It is particularly suitable for butyl rubber used in the production of inner tubes, water tires, vulcanized bladders, insulation layers for wires and cables, and general rubber products.

[0003] In existing industries, the main methods for synthesizing dibenzoyl-p-benzoquinone dioxime are:

[0004] Chinese patent document CN101293857A discloses a method for preparing dibenzoyl-p-benzoquinone dioxime. This method uses chloroform as an organic solvent and p-benzoquinone dioxime and benzoyl chloride as raw materials to synthesize dibenzoyl-p-benzoquinone dioxime in one step. Although this method is simple and easy to implement, it has a long reaction time, high material consumption, and low product yield. Under optimal experimental conditions (a molar ratio of p-benzoquinone dioxime to benzoyl chloride of 1:2.9, and a reaction time of 6 hours at 55°C), the product yield is only 90.2%, which is not conducive to large-scale production.

[0005] Chinese patent document CN102617398A discloses a method for manufacturing p,p-dibenzoylbenzoquinone dioxime compounds. This method uses ethylene glycol dimethyl ether as an organic solvent, p-benzoquinone dioxime and benzoyl chloride as raw materials, and triethylamine as a reactant to synthesize p-benzoylbenzoquinone dioxime. This synthesis process consumes a large amount of organic solvent, approximately 5 to 10 times the mass of p-benzoquinone dioxime, resulting in significant space consumption and wasted equipment space during industrial production. Furthermore, the high price of ethylene glycol dimethyl ether hinders cost control. In conclusion, this synthesis method is not suitable for large-scale industrial production.

[0006] Furthermore, both of the above synthesis methods use p-benzoquinone dioxime and benzoyl chloride as raw materials, and hydrogen chloride gas is generated during the synthesis process. Hydrogen chloride gas is highly corrosive and can form explosive mixtures with air. Therefore, in industrial production, it will inevitably cause chloride ion corrosion to the reaction equipment, thus creating safety hazards and increasing the difficulty of waste treatment. Moreover, both the raw material benzoyl chloride and the generated hydrogen chloride gas have strong pungent odors, which are detrimental to human health. Therefore, neither of these synthesis methods is suitable for large-scale industrial production.

[0007] Therefore, it is of great significance to develop a method for preparing dibenzoyl-p-benzoquinone dioxime with high reaction conversion rate, high production efficiency, few side reactions, and high safety. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor. The method uses p-benzoquinone dioxime and benzoic acid as raw materials, chloroform as the reaction solvent, 1,3-dicyclohexylcarbodiimide (DCC) as the dehydrating agent for the condensation reaction, and pyridine or triethylamine as the catalyst for the condensation reaction. Dibenzoyl-p-benzoquinone dioxime is synthesized in one step in a microchannel reactor. This method offers high reaction conversion rate, high production efficiency, few side reactions, and high safety. The obtained dibenzoyl-p-benzoquinone dioxime product has stable quality. Furthermore, the organic solvent used can be recovered and reused after vacuum distillation, overcoming the problems of inaccurate temperature control, poor safety, numerous side reactions, and difficult waste treatment in traditional processes. This provides a new approach for the synthesis of dibenzoyl-p-benzoquinone dioxime.

[0009] The technical solution of the present invention is as follows:

[0010] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor includes the following steps:

[0011] 1,3-Dicyclohexylcarbodiimide (DCC) and the catalyst were mixed evenly and preheated to obtain a premixed solution. A chloroform solution of p-benzoquinone dioxime, a chloroform solution of benzoic acid, and the premixed solution were simultaneously introduced into a microchannel reactor to carry out the reaction. The reaction solution was subjected to vacuum distillation, washing, filtration, and drying to obtain dibenzoyl-p-benzoquinone dioxime.

[0012] According to a preferred embodiment of the present invention, the mass ratio of 1,3-dicyclohexylcarbodiimide (DCC) to p-benzoquinone dioxime is (0.2-0.3):1.

[0013] According to a preferred embodiment of the present invention, the catalyst is pyridine or triethylamine; the mass ratio of the catalyst to p-benzoquinone dioxime is (0.1-0.15):1.

[0014] According to a preferred embodiment of the present invention, the temperature of the premixed solution of 1,3-dicyclohexylcarbodiimide (DCC) and catalyst is 35°C to 40°C; the mixture of 1,3-dicyclohexylcarbodiimide (DCC) and catalyst can be preheated in a preheating kettle.

[0015] According to a preferred embodiment of the present invention, the chloroform solution of p-benzoquinone dioxime has a mass fraction of 30-50%, more preferably 40%.

[0016] According to a preferred embodiment of the present invention, the chloroform solution of benzoic acid has a mass fraction of 25-35%, more preferably 30%.

[0017] According to a preferred embodiment of the present invention, the molar ratio of benzoic acid to p-benzoquinone dioxime is (2-2.1):1.

[0018] According to a preferred embodiment of the present invention, the flow rate of the chloroform solution of p-benzoquinone dioxime in the microchannel reactor is 6.5 g / min to 10 g / min; the molar ratio of the raw materials in the microreactor is controlled by controlling the flow rates of the chloroform solution of p-benzoquinone dioxime, the chloroform solution of benzoic acid, and the premix.

[0019] According to a preferred embodiment of the present invention, the reaction temperature is 35°C to 40°C, and the reaction residence time of the material in the microchannel reactor is 10 min to 15 min.

[0020] According to the present invention, the microchannel reactor is a microchannel reactor reported in the prior art, also known as a microreactor, which is commercially available, and the material flows continuously in the microchannel reactor; furthermore, the inner diameter of the microchannel reactor used is 2 mm to 4 mm.

[0021] According to the present invention, the reaction liquid flowing out from the microchannel reactor is a mixed solution of dibenzoyl-p-benzoquinone dioxime, chloroform, 1,3-dicyclohexylcarbodiimide (DCC), and catalyst. The organic solvent chloroform can be recovered by vacuum distillation, and the target product can be obtained by washing, filtering, and drying.

[0022] According to a preferred embodiment of the present invention, the temperature of the vacuum distillation is 40℃~50℃; the time of vacuum distillation is 0.5h~1.5h; and the pressure of vacuum distillation is -0.1MPa~-0.08MPa.

[0023] According to a preferred embodiment of the present invention, the washing step is as follows: water is added to the residual liquid obtained by vacuum distillation and the mixture is stirred and washed; the mass ratio of the added water to the mass of p-benzoquinone dioxime is (0.5-2):1.

[0024] According to a preferred embodiment of the present invention, the drying process involves drying the filtered solid at 80°C to 90°C until constant weight; the filtrate is then allowed to stand and separated to recover 1,3-dicyclohexylcarbodiimide (DCC) and the catalyst for reuse.

[0025] The synthetic route of this invention is as follows:

[0026]

[0027] The technical features and beneficial effects of this invention are as follows:

[0028] 1. This invention uses chloroform as the reaction solvent, which improves the dispersibility of the reaction system, accelerates the reaction rate, shortens the reaction time, and makes the reaction more complete. Simultaneously, the reactants p-benzoquinone dioxime and benzoic acid, as well as the product dibenzoyl-p-benzoquinone dioxime, are readily soluble in chloroform, facilitating the use of a microchannel reactor. Furthermore, the organic solvent chloroform can be recovered and reused through vacuum distillation, reducing material consumption and helping to reduce production costs. The recovery and reuse of the organic solvent chloroform also reduces the difficulty of wastewater treatment, which is conducive to the implementation of green environmental protection requirements.

[0029] 2. This invention uses benzoic acid as the raw material for synthesizing dibenzoyl-p-benzoquinone dioxime, which is safer and more reliable than benzoyl chloride in traditional processes. This is because traditional synthesis processes generate highly corrosive hydrogen chloride gas, which easily causes severe corrosion to reaction equipment. Furthermore, hydrogen chloride gas can react with various metals to produce hydrogen gas, can form explosive mixtures with air, and react with cyanide to produce highly toxic hydrogen cyanide, posing a significant safety hazard. However, by using weakly acidic benzoic acid instead of benzoyl chloride, the byproduct changes from hydrogen chloride gas to water. The reaction process is safe and mild, avoiding the generation of highly corrosive gases and acidic wastewater, resulting in high safety and facilitating industrial production.

[0030] 3. This invention uses 1,3-dicyclohexylcarbodiimide (DCC) as the dehydrating agent in the condensation reaction and pyridine or triethylamine as the catalyst for the condensation reaction. It is used in conjunction with pyridine or triethylamine to synthesize dibenzoyl-p-benzoquinone dioxime. This novel and highly efficient catalytic system is safer and more stable during the reaction process, causes no environmental pollution, and has low corrosiveness to equipment, making it a promising green catalyst. Furthermore, this catalytic system is entirely liquid during use, allowing for recovery of the filtrate through sedimentation and separation, which helps reduce production costs.

[0031] 4. This invention utilizes a microchannel reactor to prepare dibenzoyl-p-benzoquinone dioxime, improving reaction efficiency, shortening reaction time, and reducing material consumption. The continuous reaction of this invention not only reduces material, energy, and time costs but also minimizes side reactions and waste generation, facilitating the implementation of green environmental protection measures. Furthermore, the synthesis method using a microchannel reactor in this invention offers higher safety, simpler operation, and is more conducive to large-scale industrial production. The microchannel reaction technology employed in this invention results in high production efficiency, high reaction conversion rate, fewer side reactions, and stable quality of the target product. Simultaneously, the microchannel production technology allows for more precise temperature control during the reaction process, avoiding localized overheating. Additionally, this production method offers high safety, fewer production hazards, and contributes to inherent production safety.

[0032] 5. By controlling the material feed ratio and temperature, this invention can successfully complete tasks that cannot be accomplished under conventional methods, shortening the reaction time, increasing the selectivity of the target product, increasing the conversion rate of the reaction, and obtaining a stable and reliable product quality, which is beneficial for large-scale industrial production.

[0033] 6. Compared with existing synthesis methods, the synthesis method of this invention produces less waste, has a shorter reaction time, higher efficiency, and lower production cost; the synthesis method is simple, easy to implement, and operates under mild conditions with high safety. The obtained product is a purplish-gray powder with a yield ≥98% and a purity ≥99wt%, meeting the requirements for use and possessing industrial application value. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The inner diameter of the microchannel reactor used in the example is 4 mm.

[0036] Example 1

[0037] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor includes the following steps:

[0038] (1) Mix 10g of dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) with 5g of catalyst pyridine to obtain a mixture, and then preheat it to 38°C in a preheating kettle to obtain a premixed solution.

[0039] (2) The temperature of the microchannel reactor was controlled at 38℃. 100g of chloroform solution of p-benzoquinone dioxime with a mass fraction of 40%, 242g of chloroform solution of benzoic acid with a mass fraction of 30%, and the premixed liquid obtained in step (1) were simultaneously introduced into the microchannel reactor through different channels at a flow rate ratio of 1:2.42:0.15 to carry out dehydration condensation reaction. The flow rate of chloroform solution of p-benzoquinone dioxime was 10g / min. The reaction temperature was controlled at 38℃ and the residence time was 10min to obtain dibenzoyl-p-benzoquinone dioxime reaction solution.

[0040] (3) The obtained dibenzoyl-p-benzoquinone dioxime reaction solution was distilled under reduced pressure at 45℃ and -0.09MPa for 1h. The vapor was condensed and recovered to a chloroform buffer tank. 50g of water was added to the remaining liquid after evaporation and stirred and washed. After filtration, the obtained solid was dried at 85℃ to constant weight to obtain dibenzoyl-p-benzoquinone dioxime. The filtrate was then allowed to stand and separated to recover the mixture of dehydrating agent and catalyst.

[0041] The dibenzoyl-p-benzoquinone dioxime prepared in Example 1 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 99.12%, and the purity (HPLC) was 99.51%.

[0042] Example 2

[0043] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that: in step (1), 8g of dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) and 4g of catalyst pyridine are added; in step (2), 100g of a chloroform solution of p-benzoquinone dioxime with a mass fraction of 40%, 236g of a chloroform solution of benzoic acid with a mass fraction of 30%, and the premix obtained in step (1) are simultaneously introduced into the microchannel reactor through different channels at a flow rate ratio of 1:2.36:0.12 to carry out the dehydration condensation reaction.

[0044] The dibenzoyl-p-benzoquinone dioxime prepared in Example 2 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 98.44%, and the purity (HPLC) was 99.13%.

[0045] Example 3

[0046] A method for preparing benzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that: in step (1), 12g of dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) and 6g of catalyst pyridine are added; in step (2), 100g of a chloroform solution of 40% p-benzoquinone dioxime, 248g of a chloroform solution of 30% benzoic acid, and the premix obtained in step (1) are simultaneously introduced into the microchannel reactor through different channels at a flow rate ratio of 1:2.48:0.18 to carry out a dehydration condensation reaction.

[0047] The dibenzoyl-p-benzoquinone dioxime prepared in Example 3 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 98.75%, and the purity (HPLC) was 99.04%.

[0048] Example 4

[0049] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that pyridine is replaced with triethylamine.

[0050] The dibenzoyl-p-benzoquinone dioxime prepared in Example 4 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 98.95%, and the purity (HPLC) was 99.36%.

[0051] Example 5

[0052] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 3, except that pyridine is replaced with triethylamine.

[0053] The dibenzoyl-p-benzoquinone dioxime prepared in Example 5 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 99.05%, and the purity (HPLC) was 99.43%.

[0054] Example 6

[0055] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that the organic solvent chloroform is replaced with chloroform recovered by vacuum distillation.

[0056] The dibenzoyl-p-benzoquinone dioxime prepared in Example 6 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 98.86%, and the purity (HPLC) was 99.07%.

[0057] Example 7

[0058] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that the mixture of dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) and catalyst pyridine is replaced with a mixture of dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) and catalyst pyridine recovered in the filtrate.

[0059] The dibenzoyl-p-benzoquinone dioxime prepared in Example 7 was a purplish-gray powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 98.90%, and the purity (HPLC) was 99.01%.

[0060] Comparative Example 1

[0061] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that the dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) is not added.

[0062] The dibenzoyl-p-benzoquinone dioxime prepared in Comparative Example 1 was a purplish-brown powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 84.07%, and the purity (HPLC) was 93.25%.

[0063] Comparative Example 2

[0064] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that no catalyst pyridine is added.

[0065] The dibenzoyl-p-benzoquinone dioxime prepared in Comparative Example 2 was a purplish-brown powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 88.69%, and the purity (HPLC) was 95.02%.

[0066] Comparative Example 3

[0067] A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor is described in Example 1, except that the dehydrating agent 1,3-dicyclohexylcarbodiimide (DCC) and the catalyst pyridine are not added.

[0068] The dibenzoyl-p-benzoquinone dioxime prepared in Comparative Example 3 was a purplish-brown powder. After testing and measurement, the yield (based on p-benzoquinone dioxime) was 77.42%, and the purity (HPLC) was 82.07%.

[0069] Table 1 Comparison of results for dibenzoyl-p-benzoquinone dioxime obtained under different conditions

[0070] sample Appearance Yield % purity / % Example 1 purplish-gray powder 99.12％ 99.51％ Example 2 purplish-gray powder 98.44％ 99.13％ Example 3 purplish-gray powder 98.75％ 99.04％ Example 4 purplish-gray powder 98.95％ 99.36％ Example 5 purplish-gray powder 99.05％ 99.43％ Example 6 purplish-gray powder 98.86％ 99.07％ Example 7 purplish-gray powder 98.90％ 99.01％ Comparative Example 1 purplish-brown powder 84.07％ 93.25％ Comparative Example 2 purplish-brown powder 88.69％ 95.02％ Comparative Example 3 purplish-brown powder 77.42％ 82.07％

[0071] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor, comprising the following steps: 1,3-Dicyclohexylcarbodiimide and the catalyst were mixed evenly and preheated to obtain a premixed solution. A chloroform solution of p-benzoquinone dioxime, a chloroform solution of benzoic acid, and the premixed solution were simultaneously introduced into a microchannel reactor for reaction. The resulting reaction solution was subjected to vacuum distillation, washing, filtration, and drying to obtain dibenzoyl-p-benzoquinone dioxime. The mass ratio of 1,3-dicyclohexylcarbodiimide to p-benzoquinone dioxime was (0.2~0.3):

1. The catalyst was pyridine or triethylamine. The mass ratio of the catalyst to p-benzoquinone dioxime was (0.1~0.15):

1. The molar ratio of benzoic acid to p-benzoquinone dioxime was (2~2.1):

1.

2. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The temperature of the premixed solution of 1,3-dicyclohexylcarbodiimide and catalyst is 35℃~40℃.

3. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The mass fraction of the chloroform solution of p-benzoquinone dioxime is 30-50%.

4. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The chloroform solution of p-benzoquinone dioxime has a mass fraction of 40%.

5. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The chloroform solution of benzoic acid has a mass fraction of 25-35%.

6. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The chloroform solution of benzoic acid has a mass fraction of 30%.

7. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The flow rate of the chloroform solution of p-benzoquinone dioxime in the microchannel reactor was 6.5 g / min to 10 g / min.

8. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The reaction temperature is 35℃~40℃, and the reaction residence time of the material in the microchannel reactor is 10min~15min.

9. The method for preparing dibenzoyl-p-benzoquinone dioxime using a microchannel reactor according to claim 1, characterized in that, The vacuum distillation temperature is 40℃~50℃; the vacuum distillation time is 0.5h~1.5h; and the vacuum distillation pressure is -0.1MPa~-0.08MPa. The washing step is as follows: water is added to the residual liquid obtained by vacuum distillation and the mixture is stirred and washed; the mass ratio of the added water to the mass of p-benzoquinone dioxime is (0.5~2):1; The drying process involves drying the filtered solid at 80°C to 90°C until it reaches a constant weight.

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