Preparation method of No. 2 medium fixing agent
By adjusting the insertion position and reaction conditions of the acylation reagent during the synthesis of reagent II, the problem of excessive consumption of phosgene and triphosgene was solved, achieving higher conversion rate and lower production cost, which meets the requirements of green and environmentally friendly chemical production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHONGQING CHANGFENG CHEM IND
- Filing Date
- 2026-03-05
- Publication Date
- 2026-05-29
AI Technical Summary
The existing No. II intermediate reagent synthesis method consumes too much phosgene and triphosgene, resulting in unstable product quality and increased production costs, which does not conform to the concept of green and environmentally friendly chemical production.
By inserting the acylation reagent into the bottom of the tube in the reactor, which is located in the upper N-methylaniline layer, controlling the stirring speed and temperature, reducing the contact opportunity between the acylation reagent and the NaOH aqueous solution, and preventing triphosgene from settling to the bottom of the reactor, triphosgene solution or phosgene is used as the acylation reagent, and the reaction conditions are controlled to improve the conversion rate.
It significantly reduced the consumption of acylation reagents, improved the conversion rate of N-methylaniline and the utilization rate of triphosgene, reduced the residual impurities in the mother liquor, and improved product quality and production efficiency.
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Figure CN122102956A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis technology, specifically to a method for preparing a No. II neutralizing agent. Background Technology
[0002] Type II stabilizer (N,N'-dimethyl-N,N'-diphenylurea) is an important stabilizer for explosives. It is widely used because it can inhibit the autocatalytic thermal decomposition of nitro compounds in explosives, thereby improving the stability of explosives during processing, storage and transportation.
[0003] Currently, the main methods for synthesizing No. 2 stabilizer used in China are the phosgene method and the triphosgene method. The mechanism of phosgene participation in the reaction is shown in the figure below:
[0004] .
[0005] Side reaction: Phosgene hydrolysis
[0006] .
[0007] Side reaction intermediate acyl chloride hydrolysis:
[0008] .
[0009] The mechanism by which triphosgene participates in the reaction is shown in the figure below:
[0010] .
[0011] Side reaction three: phosgene hydrolysis
[0012] .
[0013] Side reaction intermediate acyl chloride hydrolysis:
[0014] .
[0015] The existing method for synthesizing reagent II still has the following drawbacks:
[0016] Firstly, when using phosgene as a raw material in traditional methods, the consumption of phosgene is high, often reaching 1.2-1.5 times the theoretical amount. To increase the contact area, phosgene reactors are often designed with insertion tubes close to the bottom of the reactor, or feed directly through the bottom. This results in phosgene having more contact with the NaOH solution in the lower layer of the reaction liquid, such as... Figure 1 As shown.
[0017] Secondly, the consumption of triphosgene is far higher than the theoretical amount, often reaching 1.5-2 times the theoretical amount, because the solid density of triphosgene is 1.78 g / cm³. 3 The melt density is 1.62 g / cm³.3 The density of the superoxide dismutase (SOD) is much greater than that of the lower reaction liquid, so it often sinks directly to the bottom of the reactor, significantly increasing the degree of hydrolysis of triphosgene and resulting in higher consumption. Figure 2 As shown.
[0018] Both existing technologies have drawbacks such as excessive raw material consumption and the generation of a large amount of saline wastewater, which not only easily leads to unstable product quality but also increases production costs, thus failing to meet the concept of green and environmentally friendly chemical production. Summary of the Invention
[0019] To address the aforementioned technical problems, the present invention aims to provide another method for preparing reagent II, thereby reducing reagent consumption and improving conversion rate.
[0020] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a No. II neutralizing agent, characterized by preparation according to the following steps:
[0021] (1) Add N-methylaniline, NaOH and water to the reaction vessel, start the stirrer to mix, and separate the layers. The upper layer is the N-methylaniline layer and the lower layer is the NaOH aqueous solution layer.
[0022] (2) The acylation reagent is introduced into the reaction vessel through the insertion tube, with the bottom end of the insertion tube located in the upper N-methylaniline layer. The stirring speed is controlled at 50-300 r / min, and the product is obtained by stirring. Preferably, the stirring speed is controlled at 100 r / min, and the stirring is clockwise or counterclockwise.
[0023] Preferably, the insertion tube is 1-80 cm away from the interface layer of the NaOH aqueous solution. The insertion depth is determined based on the depth of the N-methylaniline layer, preferably at two-thirds of the depth of the N-methylaniline layer. The lower end of the insertion tube is located within the N-methylaniline layer.
[0024] In the above scheme: the mass concentration of sodium hydroxide aqueous solution in the reaction vessel is 2-30%.
[0025] Preferably, the concentration of the sodium hydroxide aqueous solution is 20-30%, such as 25%.
[0026] In the above scheme: the acylation reagent is triphosgene solution or phosgene.
[0027] In the above scheme: the triphosgene solution is a triphosgene benzene solution or a triphosgene toluene solution.
[0028] In the above scheme, the reaction temperature is 100-110℃, preferably 105℃.
[0029] In the above scheme: when phosgene is used as raw material, the molar ratio of N-methylaniline to phosgene is 1.8:1-2:1; when triphosgene is used as raw material, the molar ratio of N-methylaniline to triphosgene is 5.4:1-6:1.
[0030] In the above scheme: when phosgene is used as raw material, the molar ratio of phosgene to NaOH is ≥2:1; when triphosgene is used as raw material, the molar ratio of triphosgene to NaOH is ≥6:1.
[0031] For example, when phosgene is used as the acylation reagent, n(N-methylaniline):n(phosgene) = 1.9:1, n(NaOH):n(phosgene) = 2.2:1.
[0032] When using triphosgene solution as the acylation reagent, the ratio of n(N-methylaniline):n(triphosgene) = 5.7:1 and the ratio of n(NaOH):n(triphosgene) = 6.6:1 in steps (1) or (2).
[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0034] 1. Triphosgene solution or phosgene is used as the acylation reagent, and the insertion tube for introducing the acylation reagent is designed to be located in the upper layer of N-methylaniline solution, above the interface layer between N-methylaniline and NaOH aqueous solution. This reduces the chance of the acylation reagent directly contacting the NaOH aqueous solution during the reaction. Simultaneously, this avoids the high-density solid triphosgene settling to the bottom of the reactor when used as a raw material, thus reducing side reactions between triphosgene and NaOH aqueous solution, ensuring complete conversion of N-methylaniline, and eliminating any residue of N-methylaniline and its hydrochloride in the mother liquor after the reaction, further reducing the consumption of the acylation reagent.
[0035] 2. Control the reaction temperature and stirring speed to avoid excessive stirring speed causing the raw material amine to form an emulsion with the NaOH aqueous solution, which would accelerate the hydrolysis of the acylation reagent and acyl chloride intermediate. At the same time, ensure that hydrogen chloride gas is effectively absorbed by the NaOH aqueous solution to reduce equipment corrosion and exhaust gas pollution. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of an existing phosgene-based reaction apparatus.
[0037] Figure 2 This is a schematic diagram of an existing phosgene-based reaction apparatus.
[0038] Figure 3 This is a schematic diagram of the synthesis apparatus of the present invention. Detailed Implementation
[0039] The present invention will be further described below with reference to embodiments.
[0040] In both the examples and comparative examples, the analysis of the content of reagent II and N-methylaniline impurities was performed using gas chromatography (normalization method).
[0041] The formula for calculating the conversion rate of N-methylaniline is:
[0042] N-methylaniline conversion rate = N-ethylaniline content before reaction - N-ethylaniline content after reaction
[0043] The formula for calculating the utilization rate of phosgene is:
[0044] Phosgene utilization rate = Theoretical demand for phosgene / Actual input of phosgene
[0045] The formula for calculating the selectivity of reagent II is:
[0046] Selectivity of reagent II = Content of reagent II after reaction
[0047] Example 1
[0048] This embodiment provides a method for synthesizing reagent II, the steps of which are as follows:
[0049] (1) Add 200kg of triphosgene and 800kg of pure benzene to a 3000L enamel kettle, start stirring until completely dissolved, and obtain a triphosgene-benzene solution.
[0050] (2) The above-mentioned triphosgene solution is connected to the reactor through an insertion tube. 178 kg of sodium hydroxide, 712 kg of water (i.e., 20% sodium hydroxide solution), and 412 kg of N-methylaniline are added to the reactor to form a layered mixed solution. The triphosgene solution is transported by gravity or a special pump (50 kg / h based on 100% triphosgene) through the insertion tube into the reactor. The insertion tube is located inside the N-methylaniline and 40 cm above the interface of the sodium hydroxide solution (the depth of the N-ethylaniline layer is 1.2 m).
[0051] (3) Start the stirring of the reactor and set the stirring speed to 100 r / min.
[0052] (4) The reactor is heated to 105°C by steam or heat transfer oil. Triphosgene benzene solution is introduced to start the reaction. During the reaction, water and organic vapors are refluxed through a condenser containing a -15°C CaCl2 aqueous solution.
[0053] (5) After the reaction is completed, the brine is removed by separation, then water is added and the mixture is kept warm for 30 min. The aqueous phase is removed by separation again, and then the residual water and impurities such as the fore fraction are separated by vacuum distillation. The product of the No. I stabilizer is obtained by distillation.
[0054] After the above reaction, the conversion rate of N-methylaniline was 99.6%, the utilization rate of triphosgene was 95.0%, and the selectivity of stabilizer I was 99.2%.
[0055] Example 2
[0056] This embodiment is the same as Embodiment 1, except that 196 kg of gaseous phosgene is used instead of the triphosgene-benzene solution, while the gaseous phosgene delivery rate (50 kg / h) remains the same. After the reaction, the N-methylaniline conversion rate is 99.7%, the gaseous phosgene utilization rate is 96.9%, and the selectivity of reagent I is 99.4%.
[0057] Example 3
[0058] This embodiment is the same as Embodiment 1, except that the same mass of toluene is used instead of benzene as the solvent to dissolve triphosgene. After the reaction, the conversion rate of N-methylaniline is 99.2%, the utilization rate of triphosgene is 95.0%, and the selectivity of reagent I is 98.9%.
[0059] Example 4
[0060] A method for synthesizing a No. II neutralizing agent, comprising the following steps:
[0061] (1) Add 211 kg of triphosgene and 800 kg of pure benzene to a 3000 L enamel kettle, start stirring until completely dissolved, and obtain a triphosgene-benzene solution.
[0062] (2) The above-mentioned triphosgene solution is connected to the reactor via an insertion tube. 178 kg of sodium hydroxide, 712 kg of water (i.e., 20% sodium hydroxide solution), and 412 kg of N-methylaniline are added to the reactor to form a layered mixed solution. The triphosgene solution is transported by gravity or a special pump (50 kg / h based on 100% triphosgene) through the insertion tube into the reactor. The insertion tube is located inside the N-methylaniline and 40 cm above the interface of the sodium hydroxide solution.
[0063] (3) Start the stirring of the reactor and set the stirring speed to 300 r / min.
[0064] (4) The reactor is heated to 105°C by steam or heat transfer oil. Triphosgene benzene solution is introduced to start the reaction. During the reaction, water and organic vapors are refluxed through a condenser containing a -15°C CaCl2 aqueous solution.
[0065] (5) After the reaction is completed, the brine is removed by separation, then water is added and the mixture is kept warm for 30 min. The aqueous phase is removed by separation again, and then the residual water and impurities such as the fore fraction are separated by vacuum distillation. The product of the No. I stabilizer is obtained by distillation.
[0066] After the above reaction, the conversion rate of N-methylaniline was 99.4%, the utilization rate of triphosgene was 90.0%, and the selectivity of stabilizer I was 99.2%.
[0067] Example 5
[0068] A method for synthesizing a No. II neutralizing agent, comprising the following steps:
[0069] (1) Add 200kg of triphosgene and 800kg of pure benzene to a 3000L enamel kettle, start stirring until completely dissolved, and obtain a triphosgene-benzene solution.
[0070] (2) The above-mentioned triphosgene solution is connected to the reactor via an insertion tube. 178 kg of sodium hydroxide, 712 kg of water (i.e., 20% sodium hydroxide solution), and 466 kg of N-methylaniline are added to the reactor to form a layered mixed solution. The triphosgene solution is transported by gravity or a special pump (50 kg / h based on 100% triphosgene) through the insertion tube into the reactor. The insertion tube is located inside the N-methylaniline and 30 cm above the interface of the sodium hydroxide solution.
[0071] (3) Start the stirring of the reactor and set the stirring speed to 50 r / min.
[0072] (4) The reactor is heated to 105°C by steam or heat transfer oil. Triphosgene benzene solution is introduced to start the reaction. During the reaction, water and organic vapors are refluxed through a condenser containing a -15°C CaCl2 aqueous solution.
[0073] (5) After the reaction is completed, the brine is removed by separation, then water is added and the mixture is kept warm for 30 min. The aqueous phase is removed by separation again, and then the residual water and impurities such as the fore fraction are separated by vacuum distillation. The product of the No. I stabilizer is obtained by distillation.
[0074] After the above reaction, the conversion rate of N-methylaniline was 99.9%, the utilization rate of triphosgene was 95.0%, and the selectivity of stabilizer I was 99.7%.
[0075] Comparative Example 1
[0076] This embodiment is the same as Embodiment 1, except that the insertion tube is located 80 cm below the interface between N-methylaniline and sodium hydroxide solution, and the amount of triphosgene added is 229 kg. After the reaction, the conversion rate of N-methylaniline is 99.7%, the utilization rate of triphosgene is 83.0%, and the selectivity of the No. 1 stabilizer is 99.2%.
[0077] Comparative Example 2
[0078] This embodiment is the same as Embodiment 1, except that the stirring speed is set to 350 r / min and the amount of triphosgene added is 221 kg. After the reaction, the conversion rate of N-methylaniline is 99.6%, the utilization rate of triphosgene is 86.0%, and the selectivity of the stabilizer I is 99.1%.
[0079] Comparative Example 3
[0080] This embodiment is the same as Embodiment 1, except that the reaction temperature is raised to 115°C and the amount of triphosgene added is 206 kg. After the reaction, the conversion rate of N-methylaniline is 99.3%, the utilization rate of triphosgene is 92.2%, and the selectivity of the No. 1 stabilizer is 94.2%.
[0081] Comparing Example 1 and Comparative Example 1, it can be seen that due to the difference in the position of the triphosgene introduction, the acylation reagent has limited contact with the NaOH solution, resulting in an increase in the side reactions of triphosgene hydrolysis, an increase in the amount of triphosgene used, and a significant decrease in the utilization rate of triphosgene.
[0082] Comparing Example 1 and Comparative Example 2, it can be seen that due to the increased stirring speed, the mixture is close to forming an emulsion, the mass transfer area increases significantly, resulting in more side reactions of triphosgene hydrolysis, more triphosgene usage, and a significant decrease in triphosgene utilization.
[0083] Comparing Example 1 and Comparative Example 3, it can be seen that due to the increase in reaction temperature, the hydrolysis of triphosgene and the side reactions of N-methylaniline increase, the amount of triphosgene used increases, and the utilization rate of triphosgene and the selectivity of No. 1 stabilizer decrease significantly.
[0084] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A method for preparing a No. II neutralizing agent, characterized in that, Prepare according to the following steps: (1) Add N-methylaniline, NaOH and water to the reaction vessel, start the stirrer to mix, and separate the layers. The upper layer is the N-methylaniline layer and the lower layer is the NaOH aqueous solution layer. (2) The acylation reagent is introduced into the reaction vessel through the insertion tube. The bottom end of the insertion tube is located in the upper N-methylaniline layer. The stirring speed is controlled at 50-300 r / min. The product is obtained by stirring the reaction.
2. The method for preparing the stabilizer II according to claim 1, characterized in that: The insertion tube is 1-80 cm away from the interface layer of the NaOH aqueous solution.
3. The method for preparing the stabilizer II according to claim 1 or 2, characterized in that: The mass concentration of the sodium hydroxide aqueous solution in the reactor is 2-30%.
4. The method for preparing the stabilizer II according to claim 3, characterized in that: The concentration of the sodium hydroxide aqueous solution is 20-30%.
5. The method for preparing the stabilizer II according to claim 3, characterized in that: The acylation reagent is a triphosgene solution or phosgene.
6. The method for preparing the stabilizer II according to claim 5, characterized in that: The triphosgene solution is a triphosgene benzene solution or a triphosgene toluene solution.
7. The method for preparing the stabilizer II according to claim 6, characterized in that: The reaction temperature is 100-110℃.
8. The method for preparing the stabilizer II according to claim 7, characterized in that: When phosgene is used as a raw material, the molar ratio of N-methylaniline to phosgene is 1.8:1-2:1; when triphosgene is used as a raw material, the molar ratio of N-methylaniline to triphosgene is 5.4:1-6:
1.
9. The method for preparing the stabilizer II according to claim 8, characterized in that, When phosgene is used as a raw material, the molar ratio of phosgene to NaOH is ≥2:1; when triphosgene is used as a raw material, the molar ratio of triphosgene to NaOH is ≥6:1.