A clean synthesis method and device for dibromohydantoin

Abstract

The invention discloses a kind of clean synthesis method and device of dibromohydantoin, relate to the field of chemical synthesis technology, in the clean synthesis method preparation process of dibromohydantoin provided by the present invention, using half bromine+electrolysis, 5,5-dimethylhydantoin, sodium bromide and water are added in reactor according to a certain ratio, energized electrolysis, after electrolysis 1~2h, slowly drip about a certain amount of bromine, electrolysis sodium bromide solution generates sodium hypobromite, 5,5-dimethylhydantoin and bromine and sodium hypobromite, finally generate 1,3-dibromo-5,5-dimethylhydantoin.The bromine on 1,3-dibromo-5,5-dimethylhydantoin molecules generated, all come from bromine, and bromine is almost not consumed in the sodium bromide added, and the reaction is completed, and in the mother liquor after centrifugal drying, main substance is still sodium bromide, and mother liquor can be reused, does not produce wastewater, and is green and environmentally friendly.The problem that traditional dibromohydantoin preparation method cost is too high existing in prior art is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, in particular to a clean synthesis method and device of dibromohydantoin. Background Art

[0002] Dibromohydantoin is a special brominating agent with the advantages of high active bromine content, good storage stability, and economical use. It is widely used in the chemical and pharmaceutical industries for the bromination of allyl and benzyl compounds and active aromatic rings. It is also used for environmental surface disinfection and object disinfection in various public places. Dibromohydantoin destroys the cell walls, cell membranes, proteins and nucleic acids of microorganisms, causing their death. It has the characteristics of a broad bactericidal spectrum, strong bactericidal ability, fast action, good stability, low toxicity, low corrosiveness, low irritation, easy solubility in water, safety for humans and animals, low cost and availability, and low degree of environmental pollution.

[0003] The main methods for synthesizing dibromohydantoin are: 5,5-dimethylhydantoin bromination method, 5,5-dimethylhydantoin bromination + chlorination method, and 5,5-dimethylhydantoin chlorination method. These are the main three methods.

[0004] The bromination method of 5,5-dimethylhydantoin does not use chlorine, but only half of the bromine is utilized in the synthesis process, and the other half is converted into sodium bromide, resulting in too high a unit consumption of bromine and too high a cost, making it unsuitable for industrial production.

[0005] 5,5-dimethylhydantoin bromination + chlorination method: 5,5-dimethylhydantoin is first brominated and then chlorinated. Bromine is fully utilized in the synthesis process, the unit consumption of bromine is low, and the cost is low. Chlorine is required, and chlorine is generally excessive. The tail gas needs to be equipped with a complex tail gas treatment device. In addition, wastewater containing sodium chloride is generated, and the treatment of wastewater and tail gas requires a lot of cost.

[0006] The 5,5-dimethylhydantoin chlorination method uses sodium bromide to replace bromine and adopts the full chlorination method. It requires the use of chlorine gas, half of which is excessive. The tail gas needs to be equipped with a complex tail gas treatment device. In addition, wastewater containing sodium chloride is produced. The treatment of wastewater and tail gas also requires a lot of cost.

[0007] As the country's environmental protection requirements become increasingly stringent, traditional chlorination processes are gradually restricted, the approval of chlorine-related processes is becoming increasingly difficult, and the standards for wastewater discharge are becoming increasingly stringent. Therefore, there is an urgent need to develop a clean synthesis method for dibromohydantoin. Summary of the Invention

[0008] The present application aims to provide a clean synthesis method and device for dibromohydantoin in view of the problems of low yield, serious environmental pollution and high production cost in the synthesis method of dibromohydantoin in the prior art.

[0009] To achieve the purpose of the invention, the present invention provides the following technical solutions:

[0010] On the one hand, the present application provides a clean synthesis device for dibromohydantoin, comprising a stirring device, a kettle body, a pH detector connection port, and an electrolysis device; the kettle body is hollow, and a through groove is provided on the top of the kettle body for installing the stirring device; the stirring device is rotatably installed above the kettle body; the pH detector connection port is fixedly installed below the side wall of the kettle body; and the electrolysis device is fixedly installed on both sides of the side wall of the kettle body.

[0011] A feeding port is provided above the side wall of the kettle body; a discharge port is provided at the bottom of the kettle body;

[0012] The stirring device includes a motor, a connecting rod, a stirring blade and a stirring shaft. The motor is fixedly installed above the kettle body, and the output end of the motor is fixedly connected to the connecting rod; the connecting rod is rotatably connected to the kettle body; the connecting rod extends into the hollow space of the kettle body, and the end of the connecting rod away from the motor is fixedly connected to the stirring shaft. The stirring shaft is fixedly mounted with a stirring blade to fully stir and mix the internal mixed liquid to accelerate the reaction.

[0013] The electrolysis device includes an anode electrode and a cathode electrode. The anode electrode is fixedly mounted on the side wall of one side of the kettle body, and the cathode electrode is fixedly mounted on the side wall of the kettle body away from the anode electrode. Insulating material is provided between the electrolysis device and the kettle body.

[0014] Furthermore, the pH detector connection port is connected to an external pH detector to detect the pH value of the mixed liquid inside the kettle.

[0015] On the other hand, the present application provides a clean synthesis method of dibromohydantoin, the method comprising:

[0016] Step S1. Add 5,5-dimethylhydantoin, sodium bromide and water in a certain proportion to a dibromohydantoin clean synthesis device, continue stirring, and apply power for electrolysis;

[0017] Step S2. After electrolysis for 1 to 2 hours, slowly add bromine dropwise while stirring the electrolysis until the pH is less than 9, then stop adding bromine dropwise;

[0018] Step S3. Continue electrolysis until the pH of the electrolyte is 10-12, then stop electrolysis;

[0019] Step S4. Continue to add bromine to the electrolyte in step S3 until the pH reaches 5 to 7 and stop adding bromine;

[0020] Step S5. Continue the reaction for 1 to 2 hours, then spin-dry, rinse, and spin-dry to obtain a wet crude product of 1,3-dibromo-5,5-dimethylhydantoin, which is then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin.

[0021] The present invention is further configured as follows: the molar ratio of 5,5-dimethylhydantoin, sodium bromide, and water in step 1 is 1:(0.8-1.2):(30-40);

[0022] The present invention is further configured as follows: the droplet acceleration rate in step 2 is (5-10) drops / second, wherein the content of each droplet is 50 microliters;

[0023] The present invention is further configured as follows: the molar ratio of the amount of bromine added in step 2 to 5,5-dimethylhydantoin is (0.45-0.55):1;

[0024] The present invention is further configured as follows: the molar ratio of the amount of bromine added in step 4 to 5,5-dimethylhydantoin is (0.5-0.6):1;

[0025] The present invention is further configured such that: during continuous generation, the mixed mother liquor formed by 5,5-dimethylhydantoin, sodium bromide and water can be reused;

[0026] The chemical reaction formula is:

[0027]

[0028] The present invention provides a clean synthesis method of dibromohydantoin, which has the following beneficial effects:

[0029] 1. The present invention provides a clean dibromohydantoin synthesis device; by providing a stirring device and an electrolysis device, the mixed liquid inside the device is stirred and electrolyzed, and the internal mixed liquid is fully stirred and mixed to accelerate the chemical reaction and improve production efficiency.

[0030] 2. The clean synthesis method of dibromohydantoin provided by the present invention adopts a semi-bromination + electrolysis method. 5,5-dimethylhydantoin, sodium bromide and water are added to a reactor in a certain proportion, and electrolysis is carried out. After 1-2 hours of electrolysis, a certain amount of bromine is slowly added dropwise. The sodium bromide solution is electrolyzed to generate sodium hypobromite. 5,5-dimethylhydantoin reacts with bromine and sodium hypobromite to finally generate 1,3-dibromo-5,5-dimethylhydantoin. The bromine on the 1,3-dibromo-5,5-dimethylhydantoin molecules generated by this method comes entirely from bromine, and the bromine in the added sodium bromide is almost not consumed. After the reaction is completed, the main substance in the mother liquor after centrifugation is still sodium bromide. The mother liquor can be reused without generating wastewater. This method is green and environmentally friendly. It solves the problems of high cost and high cost of treating wastewater and tail gas in the traditional dibromohydantoin preparation method in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic diagram of the three-dimensional structure of a synthesis device for dibromohydantoin of the present invention;

[0032] Figure 2 It is a partial cross-sectional schematic diagram of the front structure of a synthesis device of dibromohydantoin of the present invention;

[0033] Figure 3 It is a partial cross-sectional schematic diagram of the right side structure of a dibromohydantoin synthesis device of the present invention;

[0034] Explanation of the accompanying symbols: 1. Motor; 2. Kettle body; 3. Connecting rod; 4. pH detector connection port; 5. Anode electrode; 6. Cathode electrode; 7. Discharge port; 8. Stirring blade; 9. Stirring shaft; 10. Feeding port. DETAILED DESCRIPTION

[0035] The present invention is further described below with reference to the examples, but these examples shall not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the reagents and instruments used in the following examples are all commercially available conventional products.

[0036] Example 1:

[0037] A clean synthesis device for dibromohydantoin, such as Figure 1-Figure 3 As shown, it includes a stirring device, a kettle body 2, a pH detector connection port 4 and an electrolysis device;

[0038] like Figure 1 As shown, the pH detector connection port 4 is fixedly installed below the side wall of the kettle body 2; the pH detector connection port 4 is connected to an external pH detector to detect the pH value of the mixed liquid inside the kettle body;

[0039] like Figure 3 As shown, the kettle body 2 is hollow, and a through groove is provided on the top of the kettle body 2 for installing the stirring device; a feeding port 10 is provided above the side wall of the kettle body 2; and a discharge port 7 is provided at the bottom of the kettle body 2;

[0040] like Figure 2-Figure 3As shown, the stirring device is rotatably mounted above the kettle body 2; the stirring device includes a motor 1, a connecting rod 3, a stirring blade 8 and a stirring shaft 9, the motor 1 is fixedly mounted above the kettle body 2, and the output end of the motor 1 is fixedly connected to the connecting rod 3; the connecting rod 3 is rotatably connected to the kettle body 2; the connecting rod 3 extends to the inside of the hollow space of the kettle body 2, and the end of the connecting rod 3 away from the motor 1 is fixedly connected to the stirring shaft 9, and a stirring blade 8 is fixedly mounted on the stirring shaft 9 to fully stir and mix the internal mixed liquid to accelerate the reaction.

[0041] like Figure 2 As shown, the electrolysis device is fixedly mounted on both sides of the side walls of the kettle body 2; the electrolysis device includes an anode electrode 5 and a cathode electrode 6, the anode electrode 5 is fixedly mounted on the side wall of one side of the kettle body 2, and the cathode electrode 6 is fixedly mounted on the side wall of the kettle body 2 away from the anode electrode 5, and an insulating material is provided between the electrolysis device and the kettle body 2.

[0042] Example 2:

[0043] The present invention provides a clean synthesis method of dibromohydantoin, which not only ensures high purity and yield of the product, but also achieves resource recycling and environmental protection throughout the entire process. The method specifically comprises the following steps:

[0044] Step S1. Using the semi-bromination + electrolysis method, 1 mol of 5,5-dimethylhydantoin, 1 mol of sodium bromide, and 35 mol of water are added to a dibromohydantoin clean synthesis device (the mother liquor can be reused when continuously generated). Continuously stir and apply electricity to electrolyze the sodium bromide solution to produce sodium hypobromite.

[0045] The initial stirring ensures uniform mixing of the raw materials, creating ideal conditions for subsequent chemical reactions; at the same time, continuous stirring ensures sufficient contact between the reactants, improving reaction efficiency.

[0046] Step S2. After 1 h of electrolysis, slowly add 0.5 mol of bromine at a rate of 5 drops / second, with each drop containing 50 μl. Stir the electrolysis while adding bromine until the pH is less than 9, then stop adding.

[0047] By slowly adding bromine dropwise while stirring the electrolysis, the reaction of sodium hypobromite with 5,5-dimethylhydantoin and the reaction of bromine with sodium hydroxide and 5,5-dimethylhydantoin proceed simultaneously, thereby ensuring both the reaction rate of sodium hypobromite with 5,5-dimethylhydantoin and the reaction rate of bromine with sodium hydroxide and 5,5-dimethylhydantoin to generate sodium bromide, thereby allowing sodium bromide to continuously undergo electrolysis reaction. The addition amount and addition rate of bromine are precisely controlled to ensure the efficiency and safety of the neutralization reaction.

[0048] Step S3. Continue electrolysis until the pH of the electrolyte reaches 11, then stop electrolysis;

[0049] By stopping the addition of bromine, sodium hypobromite and 5,5-dimethylhydantoin are allowed to fully react, thereby ensuring an alkaline environment for the mixed solution.

[0050] Step S4. Continue to add 0.55 mol of bromine dropwise until the pH reaches 6 and stop adding bromine;

[0051] The alkaline environment helps to control the rate and direction of the reaction and reduce the formation of by-products.

[0052] Step S5. The reaction was continued for 1 h, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin;

[0053] Through simple treatment with a flat-plate centrifuge, effective separation of products and waste is achieved; during continuous production, the repeated use of mother liquor not only reduces production costs but also avoids wastewater discharge, which is in line with the principles of green chemistry.

[0054] Example 3:

[0055] The present invention provides a clean synthesis method of dibromohydantoin. This method not only ensures high purity and yield of the product, but also achieves resource recycling and environmental protection throughout the entire process. The method differs from Example 2 in that it specifically includes the following steps:

[0056] Step S1. Using the semi-bromination + electrolysis method, 1 mol of 5,5-dimethylhydantoin, 0.9 mol of sodium bromide, and 30 mol of water are added to a dibromohydantoin clean synthesis device (the mother liquor can be reused when continuously generated). Continuously stir and apply electricity to electrolyze the sodium bromide solution to produce sodium hypobromite.

[0057] The initial stirring ensures uniform mixing of the raw materials, creating ideal conditions for subsequent chemical reactions; at the same time, continuous stirring ensures sufficient contact between the reactants, improving reaction efficiency.

[0058] Step S2. After 1 h of electrolysis, slowly add 0.5 mol of bromine at a rate of 5 drops / second, with each drop containing 50 μl. Stir the electrolysis while adding bromine until the pH is less than 9, then stop adding.

[0059] By slowly adding bromine dropwise while stirring the electrolysis, the reaction of sodium hypobromite with 5,5-dimethylhydantoin and the reaction of bromine with sodium hydroxide and 5,5-dimethylhydantoin proceed simultaneously, thereby ensuring both the reaction rate of sodium hypobromite with 5,5-dimethylhydantoin and the reaction rate of bromine with sodium hydroxide and 5,5-dimethylhydantoin to generate sodium bromide, thereby allowing sodium bromide to continuously undergo electrolysis reaction. The addition amount and addition rate of bromine are precisely controlled to ensure the efficiency and safety of the neutralization reaction.

[0060] Step S3. Continue electrolysis until the pH of the electrolyte reaches 10, then stop electrolysis;

[0061] By stopping the addition of bromine, sodium hypobromite and 5,5-dimethylhydantoin are allowed to fully react, thereby ensuring an alkaline environment for the mixed solution.

[0062] Step S4. Continue to add 0.55 mol of bromine dropwise until the pH reaches 5 and stop adding bromine;

[0063] The alkaline environment helps to control the rate and direction of the reaction and reduce the formation of by-products.

[0064] Step S5. The reaction was continued for 1 h, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin;

[0065] Through simple treatment with a flat-plate centrifuge, effective separation of products and waste is achieved; during continuous production, the repeated use of mother liquor not only reduces production costs but also avoids wastewater discharge, which is in line with the principles of green chemistry.

[0066] Example 4:

[0067] The present invention provides a clean synthesis method of dibromohydantoin. This method not only ensures high purity and yield of the product, but also achieves resource recycling and environmental protection throughout the entire process. The method differs from Example 2 in that it specifically includes the following steps:

[0068] Step S1. Using the semi-bromination + electrolysis method, 1 mol of 5,5-dimethylhydantoin, 1.1 mol of sodium bromide, and 40 mol of water are added to a dibromohydantoin clean synthesis device (the mother liquor can be reused when continuously generated). Continuously stir and apply electricity to electrolyze the sodium bromide solution to produce sodium hypobromite.

[0069] The initial stirring ensures uniform mixing of the raw materials, creating ideal conditions for subsequent chemical reactions; at the same time, continuous stirring ensures sufficient contact between the reactants, improving reaction efficiency.

[0070] Step S2. After 1.5 h of electrolysis, 0.45 mol of bromine was slowly added dropwise at a rate of 10 drops / second, with each drop containing 50 μl. The electrolysis was stirred while adding bromine until the pH was less than 9, at which time the addition was suspended.

[0071] By slowly adding bromine dropwise while stirring the electrolysis, the reaction of sodium hypobromite with 5,5-dimethylhydantoin and the reaction of bromine with sodium hydroxide and 5,5-dimethylhydantoin proceed simultaneously, thereby ensuring both the reaction rate of sodium hypobromite with 5,5-dimethylhydantoin and the reaction rate of bromine with sodium hydroxide and 5,5-dimethylhydantoin to generate sodium bromide, thereby allowing sodium bromide to continuously undergo electrolysis reaction. The addition amount and addition rate of bromine are precisely controlled to ensure the efficiency and safety of the neutralization reaction.

[0072] Step S3. Continue electrolysis until the pH of the electrolyte reaches 12, then stop electrolysis;

[0073] By stopping the addition of bromine, sodium hypobromite and 5,5-dimethylhydantoin are allowed to fully react, thereby ensuring an alkaline environment for the mixed solution.

[0074] Step S4. Continue to add 0.6 mol of bromine dropwise until the pH reaches 6 and stop adding bromine;

[0075] The alkaline environment helps to control the rate and direction of the reaction and reduce the formation of by-products.

[0076] Step S5. The reaction was continued for 1.5 h, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin;

[0077] Through simple treatment with a flat-plate centrifuge, effective separation of products and waste is achieved; during continuous production, the repeated use of mother liquor not only reduces production costs but also avoids wastewater discharge, which is in line with the principles of green chemistry.

[0078] Example 5:

[0079] The present invention provides a clean synthesis method of dibromohydantoin. This method not only ensures high purity and yield of the product, but also achieves resource recycling and environmental protection throughout the entire process. The method differs from Example 2 in that it specifically includes the following steps:

[0080] Step S1. Using the semi-bromination + electrolysis method, 1 mol of 5,5-dimethylhydantoin, 0.8 mol of sodium bromide, and 35 mol of water are added to a dibromohydantoin clean synthesis device (the mother liquor can be reused when continuously generated). Continuously stir and apply electricity to electrolyze the sodium bromide solution to produce sodium hypobromite.

[0081] The initial stirring ensures uniform mixing of the raw materials, creating ideal conditions for subsequent chemical reactions; at the same time, continuous stirring ensures sufficient contact between the reactants, improving reaction efficiency.

[0082] Step S2. After 2 h of electrolysis, 0.55 mol of bromine was slowly added dropwise at a rate of 7 drops / second, with each drop containing 50 μl. The electrolysis was stirred while adding bromine until the pH was less than 9, at which time the addition was suspended.

[0083] By slowly adding bromine dropwise while stirring the electrolysis, the reaction of sodium hypobromite with 5,5-dimethylhydantoin and the reaction of bromine with sodium hydroxide and 5,5-dimethylhydantoin proceed simultaneously, thereby ensuring both the reaction rate of sodium hypobromite with 5,5-dimethylhydantoin and the reaction rate of bromine with sodium hydroxide and 5,5-dimethylhydantoin to generate sodium bromide, thereby allowing sodium bromide to continuously undergo electrolysis reaction. The addition amount and addition rate of bromine are precisely controlled to ensure the efficiency and safety of the neutralization reaction.

[0084] Step S3. Continue electrolysis until the pH of the electrolyte reaches 11, then stop electrolysis;

[0085] By stopping the addition of bromine, sodium hypobromite and 5,5-dimethylhydantoin are allowed to fully react, thereby ensuring an alkaline environment for the mixed solution.

[0086] Step S4. Continue to add 0.5 mol of bromine dropwise until the pH reaches 7 and stop adding bromine;

[0087] The alkaline environment helps to control the rate and direction of the reaction and reduce the formation of by-products.

[0088] Step S5. The reaction was continued for 2 h, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin;

[0089] Through simple treatment with a flat-plate centrifuge, effective separation of products and waste is achieved; during continuous production, the repeated use of mother liquor not only reduces production costs but also avoids wastewater discharge, which is in line with the principles of green chemistry.

[0090] Example 6:

[0091] The present invention provides a clean synthesis method of dibromohydantoin. This method not only ensures high purity and yield of the product, but also achieves resource recycling and environmental protection throughout the entire process. The method differs from Example 2 in that it specifically includes the following steps:

[0092] Step S1. Using the semi-bromination + electrolysis method, 1 mol of 5,5-dimethylhydantoin, 1.2 mol of sodium bromide, and 40 mol of water are added to a dibromohydantoin clean synthesis device (the mother liquor can be reused when continuously generated). Continuously stir and apply electricity to electrolyze the sodium bromide solution to produce sodium hypobromite.

[0093] The initial stirring ensures uniform mixing of the raw materials, creating ideal conditions for subsequent chemical reactions; at the same time, continuous stirring ensures sufficient contact between the reactants, improving reaction efficiency.

[0094] Step S2. After 1 h of electrolysis, 0.45 mol of bromine was slowly added dropwise at a rate of 8 drops / second, with each drop containing 50 μl. The electrolysis was stirred while adding bromine until the pH was less than 9, at which time the addition was suspended.

[0095] By slowly adding bromine dropwise while stirring the electrolysis, the reaction of sodium hypobromite with 5,5-dimethylhydantoin and the reaction of bromine with sodium hydroxide and 5,5-dimethylhydantoin proceed simultaneously, thereby ensuring both the reaction rate of sodium hypobromite with 5,5-dimethylhydantoin and the reaction rate of bromine with sodium hydroxide and 5,5-dimethylhydantoin to generate sodium bromide, thereby allowing sodium bromide to continuously undergo electrolysis reaction. The addition amount and addition rate of bromine are precisely controlled to ensure the efficiency and safety of the neutralization reaction.

[0096] Step S3. Continue electrolysis until the pH of the electrolyte reaches 10, then stop electrolysis;

[0097] By stopping the addition of bromine, sodium hypobromite and 5,5-dimethylhydantoin are allowed to fully react, thereby ensuring an alkaline environment for the mixed solution.

[0098] Step S4. Continue to add 0.6 mol of bromine dropwise until the pH reaches 5 and stop adding bromine;

[0099] The alkaline environment helps to control the rate and direction of the reaction and reduce the formation of by-products.

[0100] Step S5. The reaction was continued for 1 h, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin;

[0101] Through simple treatment with a flat-plate centrifuge, effective separation of products and waste is achieved; during continuous production, the repeated use of mother liquor not only reduces production costs but also avoids wastewater discharge, which is in line with the principles of green chemistry.

[0102] Comparative Example 1:

[0103] The main difference between this comparative example and Example 2 is that the molar ratio of 5,5-dimethylhydantoin, sodium bromide and water in this comparative example is 1:0.5:20.

[0104] Comparative Example 2

[0105] The main difference between this comparative example and Example 2 is that the molar ratio of 5,5-dimethylhydantoin, sodium bromide and water in this comparative example is 1:1.5:60.

[0106] Comparative Example 3

[0107] The main difference between this comparative example and Example 2 is that the molar ratio of the amount of bromine added in step 2 to 5,5-dimethylhydantoin in this comparative example is 0.2:1.

[0108] Comparative Example 4

[0109] The main difference between this comparative example and Example 2 is that the molar ratio of the amount of bromine added in step 2 to 5,5-dimethylhydantoin in this comparative example is 0.8:1.

[0110] Performance testing

[0111] The utilization rates of bromine and the purity of the products in Examples 2 to 6 and Comparative Examples 1 to 4 were statistically calculated, and the results are shown in Table 1.

[0112] sample Bromine utilization rate (%) Purity of product (%) Example 2 99.91 99.992 Example 3 99.42 99.974 Example 4 99.68 99.983 Example 5 98.45 99.931 Comparative Example 1 93.86 95.298 Comparative Example 2 87.76 98.732 Comparative Example 3 95.93 97.681 Comparative Example 4 89.45 96.867

[0113] In combination with Examples 2 to 6 and Comparative Examples 1 to 4, it can be seen that due to the inappropriate ratio in Comparative Examples 1 and 3, the amount of sodium bromide, water or bromine added in step 2 is insufficient, 5,5-dimethylhydantoin cannot be completely reacted, an alkaline environment cannot be formed, the purity of the bromine product is low, and the obtained target product is less; in Comparative Examples 2 and 4, due to the low amount of 5,5-dimethylhydantoin added, sodium bromide, water and bromine in step 2 are not completely involved in the reaction, the bromine utilization rate is low, the reaction time is long, and the by-products may increase, which may lead to a decrease in product purity.

[0114] Therefore, the method of the present application, on the one hand, sets the molar ratio of the initial 5,5-dimethylhydantoin, sodium bromide, water, and bromine in step 2 to 1:(0.8-1.2):(30-40):(0.45-0.55), which not only ensures the electrolysis reaction of sodium bromide and water, but also ensures an alkaline environment when adding bromine in step 4. On the other hand, the mother liquor after centrifugal drying in the method of the present application can be reused, does not generate wastewater, reduces production costs, and protects the environment.

[0115] In the description of the embodiments of the present invention, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A clean synthesis method of dibromohydantoin, characterized in that: The method includes: Step S1. Add 5,5-dimethylhydantoin, sodium bromide and water to a synthesis device, continue stirring, and apply power for electrolysis; Step S2. After 1-2 hours of electrolysis, slowly add bromine dropwise while stirring the electrolysis until the pH is less than 9, then stop adding bromine dropwise; Step S3. Continue electrolysis until the pH of the electrolyte is 10-12, then stop electrolysis; Step S4. Continue to add bromine to the electrolyte in step S3 until the pH reaches 5 to 7, then stop adding; Step S5. The reaction was continued for 1-2 hours, followed by drying, rinsing, and drying to obtain a crude wet product of 1,3-dibromo-5,5-dimethylhydantoin, which was then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin; The synthesis device in step S1 comprises a stirring device, a kettle body (2), a pH detector connection port (4) and an electrolysis device; the kettle body (2) is hollow, and a through groove is provided on the top of the kettle body (2) for installing the stirring device; the stirring device is rotatably installed above the kettle body (2); the pH detector connection port (4) is fixedly installed below the side wall of the kettle body (2), and the pH detector connection port (4) is connected to an external pH detector; the electrolysis device is fixedly installed on both sides of the side wall of the kettle body (2).

2. A clean synthesis method of dibromohydantoin according to claim 1, characterized in that, The electrolysis device comprises an anode electrode (5) and a cathode electrode (6), wherein the anode electrode (5) is fixedly mounted on a side wall of one side of the kettle body (2), and the cathode electrode (6) is fixedly mounted on a side wall of the kettle body (2) away from the anode electrode (5).

3. A clean synthesis method of dibromohydantoin according to claim 2, characterized in that, An insulating material is provided between the electrolysis device and the kettle body (2).

4. A clean synthesis method of dibromohydantoin according to claim 1, characterized in that, The molar ratio of 5,5-dimethylhydantoin, sodium bromide and water in step S1 is 1:(0.8-1.2):(30-40).

5. A clean synthesis method of dibromohydantoin according to claim 1, characterized in that, The droplet acceleration rate in step S2 is (5-10) drops / second, wherein the content of each droplet is 50 μl.

6. The clean synthesis method of dibromohydantoin according to claim 1, characterized in that: The molar ratio of the amount of bromine added in step S2 to 5,5-dimethylhydantoin is (0.45-0.55):

1.

7. The clean synthesis method of dibromohydantoin according to claim 1, characterized in that: The molar ratio of the amount of bromine added in step S4 to 5,5-dimethylhydantoin is (0.5-0.6):

1.

8. The clean synthesis method of dibromohydantoin according to claim 1, characterized in that: The following steps are involved: Step S1. 1 mol of 5,5-dimethylhydantoin, 1 mol of sodium bromide and 35 mol of water were added to the synthesis device, stirred continuously, and electrolyzed; Step S2. After 1 h of electrolysis, slowly add 0.5 mol of bromine dropwise, stirring the electrolysis while adding bromine dropwise until the pH is less than 9, then stop adding dropwise; Step S3. Continue electrolysis until the pH of the electrolyte reaches 11, then stop electrolysis; Step S4. Continue to add 0.55 mol of bromine dropwise until the pH reaches 6 and stop adding bromine; Step S5. Continue the reaction for 1 hour, then spin-dry, rinse, and spin-dry to obtain a wet crude product of 1,3-dibromo-5,5-dimethylhydantoin, which is then dried and refined to obtain 1,3-dibromo-5,5-dimethylhydantoin.

9. The clean synthesis method of dibromohydantoin according to any one of claims 1 to 8, characterized in that: During continuous generation, the mixed mother liquor formed by 5,5-dimethylhydantoin, sodium bromide and water can be reused.

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