Preparation method of diphenylguanidine
The microwave-assisted preparation method for diphenylguanidine solves the pollution and purity problems of traditional processes, achieving low-energy and high-efficiency production of high-purity diphenylguanidine and reducing ecological harm.
Patent Information
- Application Number
- CN202511059041.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-10-31
AI Technical Summary
Existing diphenylguanidine preparation processes suffer from high pollution, low efficiency, uncontrollable safety, and insufficient purity to meet industrial requirements. Traditional methods such as the diphenylthiourea method and oxidation method are subject to heavy metal pollution and color defects, while the chlorocyanide synthesis method, although simple, is not pure enough.
Diphenylguanidine was prepared by microwave-assisted reaction in a tubular reactor with a temperature controlled at 40-80℃ and a molar ratio of aniline to cyanogen chloride of 2:1-1.3. The product was then neutralized and washed with sodium hydroxide solution to obtain high-purity diphenylguanidine.
It significantly reduces energy consumption, increases reaction rate, reduces the generation of cyanide-containing waste brine, improves the yield and purity of diphenylguanidine, and reduces ecological harm at low temperatures.
Smart Images
Figure BDA0005525209530000011 
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Abstract
Description
Technical Field
[0001] This invention relates to the field of fine chemical technology, and specifically to a method for preparing diphenylguanidine. Background Technology
[0002] Diphenylguanidine is used as a medium-speed accelerator for natural and synthetic rubber. It is commonly used as an activator for thiazole, thiuram and hypoiodide accelerators. When used in combination with accelerators DM and TMTD, it can be used for continuous vulcanization.
[0003] Traditional processes for preparing diphenylguanidine typically employ methods such as the diphenylthiourea method, oxidation method, and chlorocyanide synthesis method. The core drawbacks of the diphenylthiourea method lie in its high pollution, inefficiency, and uncontrollable safety. The use of heavy metals such as lead can enter the food chain through soil and water, causing long-term ecological damage. Wastewater contains thiocyanate, sulfate, and unreacted ammonia, resulting in high treatment costs and a high risk of secondary pollution. While the oxidation method avoids heavy metal pollution and highly toxic raw materials, its color defects, safety risks, and energy efficiency bottlenecks remain unresolved issues for the industry. Currently, the chlorocyanide synthesis method for preparing diphenylguanidine has a simple process flow and convenient waste treatment, but its purity does not meet the requirements of industrial production. Therefore, existing production processes have been optimized to develop a process that meets the aforementioned needs. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for preparing diphenylguanidine.
[0005] This invention is achieved by providing a method for preparing diphenylguanidine, comprising the following steps:
[0006] Step 1: Aniline and cyanogen chloride are simultaneously introduced into a tubular reactor. Aniline and cyanogen chloride react in contact within the reactor. The temperature of the tubular reactor is controlled at 40-80℃, and microwave-assisted reaction is used to obtain crude diphenylguanidine and hydrochloric acid.
[0007]
[0008] Step 2: Filter the crude product flowing out of the tubular reactor and neutralize the feed solution with sodium hydroxide solution:
[0009] Step 3: After washing and drying the liquid, diphenylguanidine is obtained.
[0010] Preferably, the molar ratio of aniline to cyanogen chloride is 2:1-1.3.
[0011] Preferably, the molar ratio of aniline to cyanogen chloride is 2:1.3.
[0012] Preferably, the reaction temperature is 60°C.
[0013] Preferably, the sodium hydroxide is a 10% sodium hydroxide solution.
[0014] Preferably, the feed solution is neutralized to pH≈7.0 using sodium hydroxide solution.
[0015] Preferably, the detergent is toluene.
[0016] Compared with the prior art, the beneficial effects of the present invention are:
[0017] 1. Diphenylguanidine can be prepared at lower temperatures, significantly reducing energy consumption;
[0018] 2. Excess aniline can significantly inhibit the occurrence of side reactions and suppress the hydrolysis of cyanide. The intermediate aniline cyanimide (PhN=C=NPh) is easily decomposed at high temperature. Excess aniline stabilizes its structure through hydrogen bonding and prevents the carbon-nitrogen bond from breaking.
[0019] 3. Microwave-assisted technology can significantly increase the reaction rate at low temperatures;
[0020] 4. No large amount of cyanide-containing wastewater is generated during the synthesis process, reducing harm to the environment. Detailed Implementation
[0021] The present invention will be further explained below with reference to specific implementation schemes, but this is not intended to limit the scope of protection of the present invention.
[0022] Example 1
[0023] Step 1: Simultaneously introduce 186g (2mol) of aniline and 61.5g (1mol) of purified cyanogen chloride into a tubular reactor. The aniline and cyanogen chloride react in contact within the tubular reactor. The molar ratio of aniline to cyanogen chloride is 2:1. The temperature of the tubular reactor is controlled at 40℃, and microwave-assisted reaction is used.
[0024] Step 2: The crude product flowing out of the tubular reactor is filtered and neutralized with 10% sodium hydroxide (2000 mL) to a pH of 7.0.
[0025] Step 3: The feed solution was washed with toluene and then dried to obtain 160.4 g of diphenylguanidine. The yield of diphenylguanidine was 76% and the purity was 89%.
[0026] Example 2
[0027] The difference between this embodiment and Example 1 is that the temperature of the tubular reactor is 50°C, and 179.4g of diphenylguanidine is obtained, with a diphenylguanidine yield of 85% and a purity of 91%.
[0028] Example 3
[0029] The difference between this embodiment and Example 1 is that the temperature of the tubular reactor is 60°C, and 196.2g of diphenylguanidine is obtained, with a yield of 93% and a purity of 97%.
[0030] Example 4
[0031] The difference between this embodiment and Example 1 is that the temperature of the tubular reactor is 70°C, and 187.8g of diphenylguanidine is obtained, with a diphenylguanidine yield of 89% and a purity of 93%.
[0032] Example 5
[0033] The difference between this embodiment and Example 1 is that the temperature of the tubular reactor is 80°C, and 189.9g of diphenylguanidine is obtained, with a diphenylguanidine yield of 90% and a purity of 96%.
[0034] Example 6
[0035] The difference between this embodiment and Example 3 is that the molar ratio of aniline to cyanogen chloride is 2:1.1. 186g of aniline is introduced, and 67.6g of cyanogen chloride is added to the tubular reactor to obtain 198.3g of diphenylguanidine. The yield of diphenylguanidine is 94%, and the purity is 95%.
[0036] Example 7
[0037] The difference between this embodiment and Example 3 is that the molar ratio of aniline to cyanogen chloride is 2:1.2. 186g of aniline is introduced, and 73.8g of cyanogen chloride is added to the tubular reactor to obtain 196.2g of diphenylguanidine. The yield of diphenylguanidine is 93%, and the purity is 94%.
[0038] Example 7
[0039] The difference between this embodiment and Example 3 is that the molar ratio of aniline to cyanogen chloride is 2:1.3. 186g of aniline is introduced, and 80g of cyanogen chloride is added to the tubular reactor to obtain 206.8g of diphenylguanidine. The yield of diphenylguanidine is 98%, and the purity is 98%.
Claims
1. A method for preparing diphenylguanidine, characterized in that, Includes the following steps: Step 1: Aniline and cyanogen chloride are simultaneously introduced into a tubular reactor. Aniline and cyanogen chloride react in contact within the reactor. The temperature of the tubular reactor is controlled at 40-80℃, and microwave-assisted reaction is used to obtain crude diphenylguanidine and hydrochloric acid. Step 2: Filter the crude product flowing out of the tubular reactor and neutralize the feed solution with sodium hydroxide solution; Step 3: After washing and drying the liquid, diphenylguanidine is obtained.
2. The method for preparing diphenylguanidine according to claim 1, characterized in that: In step 1, the molar ratio of aniline to cyanogen chloride is 2:1-1.
3.
3. The method for preparing diphenylguanidine according to claim 2, characterized in that: In step 1, the molar ratio of aniline to cyanogen chloride is 2:1.
3.
4. The method for preparing diphenylguanidine according to claim 1, characterized in that: In step 1, the reaction temperature is 60°C.
5. The method for preparing diphenylguanidine according to claim 1, characterized in that: In step 2, the sodium hydroxide is a 10% sodium hydroxide solution.
6. The method for preparing diphenylguanidine according to claim 1, characterized in that: In step 2, the feed solution is neutralized to pH ≈ 7.0 using sodium hydroxide solution.
7. The method for preparing diphenylguanidine according to claim 1, characterized in that: In step 3, the detergent is toluene.