Preparation method of centralite II

Abstract

The invention relates to a preparation method of a centralite II, which comprises the following steps: 1) adding N-methylaniline into an alkaline aqueous solution, and mixing to obtain an N-methylaniline mixed solution; 2) adding bis (trichloromethyl) carbonic acid into the N-methylaniline mixed solution, and stirring for reaction; in the reaction process, the reaction temperature is maintained to be lower than 105 DEG C by controlling the adding rate of the bis (trichloromethyl) carbonic acid, and a reaction product is obtained; and 3) carrying out solid-liquid separation on the reaction product to obtain the centralite I. According to the invention, solid triphosgene is used as a raw material, the centralite II is prepared by a one-pot method, the preparation process is stable, and the reaction yield can reach more than 95% when the solid triphosgene accounts for 105-110% of theoretical charging. Meanwhile, the whole reaction process is safe and stable in the whole preparation process, and pollution is small.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a preparation method of a No. II neutralizing agent. Background Art

[0002] Neutralizer is a kind of stabilizer widely used in the field of explosives. Among them, urea neutralizer is widely used at home and abroad because of its good compatibility. The main components of explosives are nitrocellulose and nitroglycerin. They will automatically decompose at room temperature and accelerate decomposition when heated. Under normal storage conditions, nitrocellulose will undergo slow thermal decomposition, the nitrate ester bond in the molecular chain will break, and a large amount of nitrogen oxide gas and heat will be released, which will accelerate thermal decomposition and form an autocatalytic process. Nitroglycerin, like nitrocellulose, also contains nitrate ester bonds in its molecular chain. At room temperature, high-purity nitroglycerin will decompose slowly, but nitroglycerin containing impurities will decompose by itself, releasing a large amount of nitrogen oxide gas and heat, and catalyzing the thermal decomposition of nitroglycerin. Therefore, it is necessary to add neutralizers during the production process to improve the stability of explosives.

[0003] At present, the main application in China is the No. Ⅱ neutralizer, but the existing preparation method of No. Ⅱ neutralizer has the following disadvantages: first, phosgene must be used as the production raw material, which is highly dangerous and harmful to people and the environment, and has great pressure on safety and environmental protection; second, the product quality is unstable, and the current production process purification technology of No. Ⅱ neutralizer is vacuum distillation, and the quality of the obtained product is not stable enough; third, the traditional process is labor-intensive, and the production process is highly polluting and high-risk, which poses a hidden danger to the health of employees. Therefore, we should increase our efforts to promote the implementation of new technologies, complete technological upgrades, promote the upgrading of the neutralizer industry, enhance the risk response capabilities of the supply chain, build a safe and stable neutralizer supply system, and ensure the security of my country's national defense industry. Summary of the invention

[0004] In order to solve the problems of complex process, high risk and unstable quality in the prior art, the present invention proposes a preparation method of No. Ⅱ neutralizing agent.

[0005] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A method for preparing a No. Ⅱ medium fixative comprises the following steps:

[0007] Step 1) adding N-methylaniline to an alkaline aqueous solution and mixing to obtain an N-methylaniline mixed solution;

[0008] Step 2) adding bistrichloromethyl carbonate to the N-methylaniline mixture and stirring for reaction; during the reaction, the reaction temperature is maintained below 105° C. by controlling the addition rate of bistrichloromethyl carbonate to obtain a reaction product;

[0009] Step 3) The reaction product is subjected to solid-liquid separation to obtain a No. 1 intermediate.

[0010] Optionally, the pH of the alkaline aqueous solution in step 1) is 10-14.

[0011] Optionally, the mass fraction of N-methylaniline in the N-methylaniline mixed solution is 30-45%.

[0012] Optionally, in the step 2), the weight ratio of the added trichloromethylcarbonic acid to the N-methylaniline is controlled to be 0.48-0.52:1.

[0013] Optionally, in step 2), the stirring rate is controlled to be 200-400 r / min.

[0014] Optionally, in the step 2), the relative pressure during the reaction is controlled to be lower than -0.03 MPa.

[0015] Preferably, the relative pressure during the vacuum distillation process is -0.01 to -0.03 MPa.

[0016] Optionally, in the step 2), during the reaction, an oily product in the upper layer of the N-methylaniline mixed solution is extracted, and the residual amine content in the oily product is detected, and the reaction is terminated when the residual amine content is lower than 0.2%.

[0017] Optionally, after the solid-liquid separation in step 3), the mixture is washed with water to obtain a No. Ⅱ neutralizing agent.

[0018] Optionally, the method further comprises:

[0019] Step 4) subjecting the No. Ⅱ intermediate fixer in step 3) to vacuum distillation to obtain refined No. Ⅱ intermediate fixer.

[0020] Optionally, the relative pressure during the vacuum distillation process is lower than -0.1 MPa and the temperature is 205°C to 240°C.

[0021] Preferably, the relative pressure during the vacuum distillation process is -0.09 to -0.1 MP.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention uses solid triphosgene as a raw material and adopts a one-pot method to prepare a No. II intermediate agent. The preparation process is stable. When the solid phosgene is 105% to 110% of the theoretical feed, the reaction yield can reach more than 95%. At the same time, the entire reaction process is safe and stable, and the pollution is small. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions and advantages of the present invention more clear, the following will be further described in detail in conjunction with the embodiments of the present invention.

[0025] The invention provides a neutralizing agent No. II by a one-pot method under alkaline conditions using N-methylaniline and bistrichloromethyl carbonate (solid triphosgene). In the reaction process, N-methylaniline chloride is first generated, and then N-methylaniline chloride is subjected to a condensation reaction with N-methylaniline to generate N,N-dimethyldiphenylurea (neutralizing agent No. II), and the byproduct hydrogen chloride reacts with sodium hydroxide to generate sodium chloride and water.

[0026] Reaction mechanism:

[0027]

[0028] Reaction equation:

[0029] No. Ⅱ medium dose:

[0030]

[0031] Mother solution:

[0032] HCl+NaOH→NaCl+H2O

[0033] Side effects:

[0034] Cl3CO-CO-OCCl3+12NaOH→3Na2CO3+6NaCl+6H2O

[0035] Test analysis method

[0036] Residual amine detection method:

[0037] Take 1.0 g of crystals from the upper layer of the synthesis reactor, press the water with filter paper, weigh on a balance (accurate to 0.01 g), then put it in a mortar, add 30 ml of hydrochloric acid for grinding. Pour the ground material into a beaker, wash the mortar with distilled water, and merge the solution into the beaker. The total volume of the solution should not exceed 300 ml. Add 10 ml of potassium bromide to the suspension in the beaker, and titrate with 0.01M sodium nitrite standard solution at 0℃-5℃ until a blue spot appears on the starch potassium iodide test paper. The end point is to keep it for 5 minutes without disappearing. Record the number of milliliters titrated.

[0038] Calculate the residual amine content W1:

[0039]

[0040] Where:

[0041] w1——N-methylaniline mass percentage

[0042] v1——mL of sodium nitrite solution consumed

[0043] c——molar concentration of sodium nitrite solution

[0044] 0.1212——milligram molar amount of N-methylaniline

[0045] G——sample weight (g)

[0046] Yield calculation

[0047]

[0048]

[0049] Where:

[0050] Yield (合成) ——Synthesis yield of crude methyl neutralizer

[0051] m1——Mass of crude methyl neutralizer (g)

[0052] m2——Theoretical mass of methyl neutralizer product (g)

[0053] M——Molecular mass of methyl neutralizer (g / mol)

[0054]

[0055] Where:

[0056] Yield (精馏) ——Synthesis yield of crude methyl neutralizer

[0057] m3——Product mass of methyl neutralizer (g)

[0058] m4——Mass of the front fraction (g)

[0059] m5——Mass of crude methyl neutralizer added (g)

[0060] Melting point test

[0061] Take a small amount of sample and grind it into the finest powder possible in a mortar, then put it into a clean, dry melting point tube. Take a dry glass tube (or plastic tube) with a length of at least about 800 mm, stand it upright on a glass plate, and drop the melting point tube containing the sample into it several times until the sample in the melting point tube is compressed to 2-3 mm high.

[0062] First, slowly raise the temperature of the heat transfer liquid to 10°C lower than the initial temperature within the melting point range specified in the sample specification, about 110°C. At this time, attach the melting point tube containing the sample to the measuring thermometer, so that the sample end of the melting point tube is at the same level as the middle of the mercury ball, and the mercury ball of the measuring thermometer should be located in the middle of the heat transfer liquid. Keep the heating rate stable at (1.0±0.1°C) / min. The temperature when the sample shows obvious local liquefaction is the initial melting temperature, and the temperature when the sample is completely melted is the final melting temperature. Record the initial temperature and the final melting temperature.

[0063] The melting point is the temperature from the initial melting point to the final melting temperature, and the final melting temperature minus the initial melting temperature is the melting range.

[0064] Embodiment 1:

[0065] Sample synthesis:

[0066] (1) First, 80.20 g of water and 161.79 g of 30% NaOH aqueous solution were added to the reactor, the circulating water vacuum pump was turned on, stirring was started, the stirring speed was controlled at about 200 revolutions per minute, and then 140.69 g of N-methylaniline was added.

[0067] (2) Slowly add solid granular bistrichloromethyl carbonate into the reactor, and keep the reaction state until oil is generated in the reactor. After a period of time, take a sample of the upper oil to analyze the residual aromatic amine content. During the reaction, vacuum is drawn to maintain the relative pressure at -0.02 MPa.

[0068] (3) According to the results of the central control analysis, if the standard is met, the stirring is stopped and the subsequent stratification and water washing are carried out. If the standard is not met, bistrichloromethyl carbonate is continued to be added for synthesis reaction until the analysis results meet the standard. The highest temperature during the reaction is 102°C, and the amount of bistrichloromethyl carbonate used is 71.59g.

[0069] (4) Filtering the obtained product, washing it with water, and then drying it until it is substantially free of water.

[0070] (5) Record product weight, crystal form, and appearance, and analyze product amine residue, melting point, and melting range.

[0071] Embodiments 2 to 11

[0072] The amount of raw materials added and the maximum reaction temperature were adjusted as shown in Table 1. The other preparation processes were the same as those in Example 1.

[0073] Comparative Examples 1 and 2

[0074] The amount of raw materials added and the maximum reaction temperature were adjusted as shown in Table 1. The other preparation processes were the same as those in Example 1.

[0075] Table 1 Main data of synthesis process

[0076]

[0077] Table 2 Synthesis experimental results

[0078]

[0079]

[0080] As shown in Tables 1 and 2, when bistrichloromethyl carbonate is added in an excess of about 5%-10% (i.e., the weight ratio of trichloromethyl carbonate to N-methylaniline is 0.48-0.52:1), the product yield tends to be stable and can reach about 96%. At this time, N-methylaniline is almost completely converted into a neutralizing agent product, the residual aromatic amines in the product are less than 0.1%, the melting range of the product is between 115°C and 122°C, and the product purity is relatively high. Therefore, it is recommended that bistrichloromethyl carbonate be added in an excess of 5%-10%.

[0081] In the entire synthesis process, in addition to the feed ratio, the operation process also plays a key role. The synthesis reaction is an exothermic reaction. During the feeding process, solid phosgene needs to be slowly added to the system, and the maximum reaction temperature is generally controlled at 101℃-105℃. The purpose is to allow the solid phosgene to fully react with N-methylaniline, improve the reaction efficiency and increase the yield, and to prevent the temperature from rising too fast, causing the system to boil over and cause unnecessary losses.

[0082] Example 12

[0083] Vacuum distillation

[0084] (1) The crude neutralizer prepared in Example 1 was added to a distiller, and the vacuum pump was turned on to control the system pressure to -0.09 to -0.1 MPa, and the pipeline temperature was kept above 120 degrees Celsius.

[0085] (2) The crude product of the intermediate fixer is subjected to distillation treatment at 205° C.-230° C., and after the distilled sample becomes a colorless transparent liquid, it is collected into a finished product bottle to obtain a refined intermediate fixer finished product.

[0086] (3) Record the weight of the finished product and analyze the product, the residual amine in the fore fraction, the melting point, and the melting range.

[0087] Embodiments 13 to 16

[0088] Adjust the reaction parameters as shown in Table 1.

[0089] Table 3 Distillation experimental results

[0090] Serial number temperature pressure Amine Residue % Yield % Melting range(℃) Example 12 226 -0.093 0.01 93.6 121-122.5 Embodiment 13 218 -0.095 0.01 96.4 120-122.5 Embodiment 14 215 -0.095 0.01 97.8 120-122.5 Embodiment 15 208 -0.097 0 96.0 120-122.5 Example 16 210 -0.096 0 98.6 120-122.5 Comparative Example 3 200 -0.095 0.01 89.1 121-122.5 Comparative Example 4 249 -0.087 0.02 90.8 119-121

[0091] As shown in Table 3, in the distillation test, since the boiling point of the methyl neutralizer at room temperature is 350°C, it is difficult to distill it out by atmospheric distillation, so the system needs to maintain a certain vacuum degree. Generally speaking, the better the vacuum degree, the higher the yield of the finished product obtained by distillation. Therefore, in the distillation experiment, the relative pressure needs to be kept below -0.09MPa, and the temperature needs to be controlled between 205°C and 240°C. In this temperature range, the residual amount of aromatic amines contained in the crude product can basically be removed, the product appearance is good, and the total yield is relatively ideal. At the same time, the distillation residue is a black solid without any odor. The composition analysis of the distillation residue shows that it is mainly composed of inorganic salts, neutralizer residues and organic high boiling substances. The residue was subjected to a destructive test and roasted at high temperature with a spray gun. The results show that the residue has no risk of explosion.

[0092] In summary, the present invention increases the amount of solid triphosgene used on the basis of a theoretical feed ratio of 1:6 of a molar ratio of solid triphosgene to N-methylaniline, with an excess of 5%-10% of solid triphosgene and a maximum reaction temperature of 101-105° C. The No. II intermediate is prepared using the improved process flow, and the yield of the prepared sample is 95%-96%, the process is stable, and the product performance after distillation is excellent, and all indicators are better than the national standards.

[0093] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a No. Ⅱ medium fixative, characterized in that: The following steps are included: Step 1) adding N-methylaniline to an alkaline aqueous solution and mixing to obtain an N-methylaniline mixed solution; Step 2) adding bistrichloromethyl carbonate to the N-methylaniline mixture and stirring for reaction; during the reaction, the reaction temperature is maintained below 105° C. by controlling the addition rate of bistrichloromethyl carbonate to obtain a reaction product; Step 3) The reaction product is subjected to solid-liquid separation to obtain a No. 1 intermediate.

2. The method for preparing the No. Ⅱ medium fixative according to claim 1, characterized in that: The pH of the alkaline aqueous solution in step 1) is 10-14.

3. The method for preparing the No. Ⅱ medium fixative according to claim 1, characterized in that: The mass fraction of N-methylaniline in the N-methylaniline mixed solution is 30-45%.

4. The method for preparing the No. Ⅱ medium fixative according to claim 1, characterized in that: In the step 2), the weight ratio of the added trichloromethylcarbonic acid to the N-methylaniline is controlled to be 0.48-0.52:

1.

5. The method for preparing the No. Ⅱ neutralizing agent according to claim 1, characterized in that: In the step 2), the stirring rate is controlled to be 200-400 r / min.

6. The method for preparing the No. Ⅱ neutralizing agent according to claim 1, characterized in that: In the step 2), the relative pressure during the reaction is controlled to be lower than -0.03 MPa.

7. The method for preparing the No. Ⅱ neutralizing agent according to claim 1, characterized in that: In the step 2), during the reaction, the oily product on the upper layer of the N-methylaniline mixed solution is extracted, and the residual amine content in the oily product is detected. When the residual amine content is less than 0.2%, the reaction is terminated.

8. The method for preparing the No. Ⅱ neutralizing agent according to claim 1, characterized in that: After the solid-liquid separation in the step 3), the mixture is washed with water to obtain a No. II neutralizing agent.

9. The method for preparing the No. Ⅱ neutralizing agent according to claim 1, characterized in that: The method further comprises: Step 4) subjecting the No. Ⅱ intermediate fixer in step 3) to vacuum distillation to obtain refined No. Ⅱ intermediate fixer.

10. The method for preparing the No. Ⅱ neutralizing agent according to claim 9, characterized in that: The relative pressure in the vacuum distillation process is lower than -0.1 MPa and the temperature is 205°C to 240°C.

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