Preparation method of centralite I

Abstract

The invention relates to a preparation method of a centralite I. The preparation method comprises the following steps: 1) adding N-ethylaniline into an alkaline aqueous solution, and mixing to obtain an N-ethylaniline mixed solution; 2) adding bis (trichloromethyl) carbonic acid into the N-ethylaniline mixed solution, and stirring for reaction; in the reaction process, the feeding reaction temperature is maintained to be lower than 110 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. Solid triphosgene is used as a raw material, the centralite I is prepared by a one-pot method, and the preparation process is stable. In the whole reaction process, the whole preparation process is safe and stable, and pollution is small.

Description

Technical Field

[0001] The invention relates to the field of chemical industry, and in particular to a method for preparing a No. 1 intermediate fixative. 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 stabilizer used in China is No. Ⅱ (N, N-dimethyldiphenylurea). The molecular structure of No. Ⅰ (N, N-diethyldiphenylurea) contains two ethyl structures connected to N. Its electronic effect is weaker than that of No. Ⅱ, which contains a methyl structure. It has a lower electron cloud density and a smaller hydrogen bond effect. Therefore, the intermolecular force of No. Ⅰ is smaller than that of No. Ⅱ, the compound has a lower melting point and better compatibility in product applications. However, since the N-ethylaniline used in the synthesis of No. Ⅰ contains an ethyl group, it has a large steric hindrance during the reaction and a difficult preparation process. This makes it difficult to promote the use of No. Ⅰ. Summary of the invention

[0004] In order to solve the problem of difficulty in preparing No. Ⅰ intermediate fixer in the prior art, the present invention proposes a preparation method of No. Ⅰ intermediate fixer.

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

[0006] A method for preparing a No. 1 medium fixative comprises the following steps:

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

[0008] Step 2) adding bistrichloromethyl carbonate to the N-ethylaniline mixture and stirring for reaction; during the reaction, the addition rate of bistrichloromethyl carbonate is controlled to maintain the reaction temperature below 110° C. after the addition is completed, 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; the mass fraction of N-ethylaniline in the N-ethylaniline mixed solution is 25-30%.

[0011] Optionally, the duration of adding bistrichloromethyl carbonate to the N-ethylaniline mixed solution in step 2) is greater than 50 minutes.

[0012] Optionally, in the step 2), the weight ratio of the added trichloromethylcarbonic acid to N-ethylaniline is controlled to be 0.49-0.52:1.

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

[0014] Optionally, in step 2), the relative pressure of the reaction is controlled to be lower than -0.01 MPa.

[0015] Optionally, in step 2), the reaction relative pressure is controlled to be -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-ethylaniline 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 less than 0.2%.

[0017] Optionally, in the step 3), the reaction product is cooled to 60-70° C., and then solid-liquid separation is performed; after solid-liquid separation, the solid phase product is washed with water to obtain a neutralizing agent No. I.

[0018] Optionally, the method further includes: step 4) subjecting the No. 1 intermediate fixer in step 3) to vacuum distillation to obtain refined No. 1 intermediate fixer.

[0019] Optionally, the relative pressure during the vacuum distillation process is lower than -0.09 MPa and the temperature is 200°C to 230°C.

[0020] Preferably, the relative pressure during the vacuum distillation process is -0.09 to -0.1 MPa.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] The present invention uses solid triphosgene as a raw material, adopts a one-pot method to prepare a No. 1 neutralizing agent, and has a stable preparation process. The entire preparation process is safe and stable during the entire reaction process, and has less pollution.

[0023] When the solid triphosgene feed ratio is 120-125% of the theoretical value, the feeding time is extended to 50-60 min, and the yield of the No. 1 intermediate agent product prepared by water-soluble cooling crystallization is greater than 96%, and the performance of the products after distillation is significantly greater than the national indicators. DETAILED DESCRIPTION

[0024] In the present invention, N-ethylaniline and bistrichloromethyl carbonate (solid triphosgene) are reacted under alkaline conditions to generate N-ethylaniline chloride, which is then condensed with N-ethylaniline to generate N,N-diethyldiphenylurea (No. Ⅰ neutralizer), and the byproduct hydrogen chloride reacts with sodium hydroxide to generate sodium chloride and water.

[0026] Reaction mechanism:

[0027]

[0028] Reaction equation:

[0029] No. Ⅰ Medium Fixing Agent

[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, squeeze out the water with filter paper, weigh on a balance (accurate to 0.01 g), then put it in a mortar, add 10 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-ethylaniline 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-ethylaniline

[0045] G——sample weight (g)

[0046] Yield calculation

[0047]

[0048] Where:

[0049] Yield (合成) ——Synthesis yield of crude ethyl neutralizer

[0050] m1——mass of crude ethyl neutralizer (g)

[0051] m2——Theoretical mass of ethyl neutralizer product (g)

[0052] M——Ethyl neutralizer molar mass (g / mol)

[0053]

[0054] Where:

[0055] Yield (精馏) ——Synthesis yield of crude ethyl neutralizer

[0056] m3——Product mass of ethyl neutralizer (g)

[0057] m4——mass of ethylene fraction (g)

[0058] m5——Mass of crude ethyl neutralizer added (g)

[0059] Melting point test

[0060] 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.

[0061] 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.

[0062] 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.

[0063] Embodiment 1:

[0064] Sample synthesis:

[0065] (1) First, 115.45 g of water and 220.79 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 120.13 g of N-ethylaniline was added.

[0066] (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.

[0067] (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. During the reaction process, the highest temperature is 105.6°C, the amount of bistrichloromethyl carbonate is 61.93g, and the feeding duration is 54min.

[0068] (4) The reactor was cooled to 62.1°C in a water bath, and a solid sample was obtained after the system was crystallized. The obtained product was filtered, washed with water, and then dried until it was substantially free of water.

[0069] (5) Record product weight, crystal form, and appearance, and analyze product amine residue, melting point, and melting range.

[0070] Embodiments 2 to 9

[0071] The reaction parameters were adjusted as shown in Table 1.

[0072] Comparative Examples 1 and 2

[0073] Adjust the reaction parameters as shown in Table 1

[0074] Table 1 Main data of synthesis process

[0075]

[0076] Table 2 Synthesis experimental results

[0077] batch Appearance shape Gross weight(g) Net weight(g) Amine Residue % Yield % Melting range(℃) Example 1 White powder 142.46 123.25 0.01 94.74 67-72 Example 2 White powder 147.35 125.61 0.01 96.24 66-71.5 Example 3 White powder 146.95 124.89 0.01 96.01 68-72 Example 4 White powder 149.10 126.43 0.01 96.56 67-72 Example 5 White powder 149.5 126.85 0.01 96.88 66-71.7 Example 6 White powder 148.96 125.91 0.01 96.24 67-71.5 Example 7 White powder 196.23 160.90 0.01 95.56 68-72 Example 8 White powder 146.56 128.10 0.01 97.00 68-72.2 Example 9 White powder 147.35 128.54 0.01 97.30 67-71.7 Comparative Example 1 Light yellow powder 135.69 118.65 0.02 89.21％ 66-71.7 Comparative Example 2 White powder 139.56 121.12 0.02 91.75 68-71.9

[0078] As shown in Tables 1 and 2, due to the large steric hindrance of the ethyl group contained in N-ethylaniline, it is easy to cause incomplete reaction. In order to solve this problem, the addition time is slowed down and the heating jacket is turned on during the addition of solid triphosgene to allow it to react fully. The data results show that the yield of the No. Ⅰ intermediate obtained after the improved process is significantly improved, and the yield can be kept stable at more than 96% when the solid triphosgene is in excess of 20-25%.

[0079] Due to the special molecular structure of the No. Ⅰ stabilizer, its melting point is low, and it is difficult to separate the sample. After the reaction is completed, it is necessary to cool it in a water bath to crystallize the No. Ⅰ stabilizer sample, which appears as a white solid crystal. Therefore, the improved No. Ⅰ stabilizer synthesis process is stable, the yield is greater than 96%, and the sample obtained is of excellent quality and appears as a white powder solid.

[0080] Therefore, in order to ensure the stability and efficiency of the process flow of the No. 1 intermediate fixer, it is necessary to increase the amount of solid triphosgene used to 120-125% of the theoretical value, extend the feeding time, and use a water-soluble cooling crystallization method to obtain the No. 1 intermediate fixer sample.

[0081] Embodiment 10, 11

[0082] Vacuum distillation

[0083] (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°C.

[0084] (2) The crude product of the intermediate fixer is subjected to distillation treatment at 200° 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.

[0085] (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.

[0086] Comparative Examples 3 and 4

[0087] The temperature and pressure of the vacuum distillation were adjusted as shown in Table 1.

[0088] Table 3 Distillation experimental results

[0089] Serial number Temperature(℃) Pressure(MPa) Amine Residue % Yield % Melting range(℃) Example 10 203 -0.96 0.01 97.6 71-72.5 Embodiment 11 226 -0.91 0.01 97.2 71-72 Comparative Example 3 245 -0.85 0.01 95.1 70-71.5 Comparative Example 4 195 -0.92 0.02 93.5 71-72.5

[0090] As shown in Table 3, in the distillation test, due to the high boiling point of the ethyl neutralizer at room temperature, 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 vacuum degree needs to be kept below -0.09MPa, and the temperature needs to be controlled between 200℃-230℃. 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. The neutralizer product after distillation is a white powder sample with a stable yield greater than 97%. The distillation residue is a black solid without any odor. At the same time, the distillation residue is mainly composed of inorganic salts, neutralizer residues and organic high boiling substances, which are easy to handle without the risk of explosion.

[0091] In summary, when the solid triphosgene feed ratio is 120-125% of the theoretical value, the feeding time is extended to 50-60 min, and the yield of the No. 1 intermediate agent product prepared by water-soluble cooling crystallization is greater than 96%, the preparation process is stable, and the product performance after distillation is significantly greater than the national indicators.

[0092] 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. 1 medium fixative, characterized in that: The following steps are included: Step 1) adding N-ethylaniline to an alkaline aqueous solution and mixing to obtain an N-ethylaniline mixed solution; Step 2) adding bistrichloromethyl carbonate to the N-ethylaniline mixture and stirring for reaction; during the reaction, the addition rate of bistrichloromethyl carbonate is controlled to maintain the reaction temperature below 110° C. 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 No. 1 medium fixative according to claim 1, characterized in that: The pH of the alkaline aqueous solution is 10-14; the mass fraction of N-ethylaniline in the N-ethylaniline mixed solution is 25-30%.

3. The preparation method of No. 1 medium fixative according to claim 1, characterized in that, The duration of adding bistrichloromethyl carbonate to the N-ethylaniline mixed solution in step 2) is greater than 50 minutes.

4. The preparation method of No. 1 medium fixative according to claim 1, characterized in that, In the step 2), the weight ratio of the added trichloromethylcarbonic acid to the N-ethylaniline is controlled to be 0.49-0.52:

1.

5. The preparation method of No. 1 medium fixative 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. 1 medium fixative according to claim 1, wherein In the step 2), the reaction relative pressure is controlled to be lower than -0.01 MPa.

7. The method for preparing No. 1 medium fixative according to claim 1, characterized in that: In the step 2), during the reaction, the oily product on the upper layer of the N-ethylaniline 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 No. 1 medium fixative according to claim 1, characterized in that: In the step 3), the reaction product is cooled to 60-70° C., and then solid-liquid separation is performed; after solid-liquid separation, the solid phase product is washed with water to obtain a No. 1 neutralizing agent.

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

10. The method for preparing the No. 1 medium fixative according to claim 9, characterized in that: The relative pressure in the vacuum distillation process is lower than -0.09 MPa and the temperature is 200°C to 230°C.

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