A preparation method of No. 1 medium fixative

Abstract

The present invention relates to a preparation method of a No. 1 neutralizing agent, comprising the following steps: step 1) adding N-ethylaniline to an alkaline aqueous solution and mixing to obtain an N-ethylaniline mixed solution; step 2) adding bis(trichloromethyl)carbonic acid to the N-ethylaniline mixed solution and stirring the reaction; maintaining the feed reaction temperature less than 110°C by controlling the addition rate of bis(trichloromethyl)carbonic acid during the reaction to obtain a reaction product; step 3) performing solid-liquid separation on the reaction product to obtain No. 1 neutralizing agent. The present invention uses solid triphosgene as a raw material, adopts a one-pot process to prepare No. 1 neutralizing agent, and has a stable preparation process. The entire preparation process is safe, stable, and less polluting during the entire reaction process.

Description

Technical Field

[0001] The present invention relates to the field of chemical industry, and in particular to a method for preparing a No. 1 neutralizing agent. Background Art

[0002] Neutralizers are widely used as stabilizers in explosives and propellants. Urea-based stabilizers are particularly popular both domestically and internationally due to their excellent compatibility. Nitrocellulose and nitroglycerin, the main components of explosives, decompose automatically at room temperature, but decomposition accelerates when heated. Under normal storage conditions, nitrocellulose undergoes slow thermal decomposition, breaking the nitrate ester bonds in its molecular chain, releasing large amounts of nitrogen oxide gas and heat, which further accelerates thermal decomposition and forms an autocatalytic process. Nitroglycerin, like nitrocellulose, also contains nitrate ester bonds in its molecular chain. At room temperature, high-purity nitroglycerin decomposes slowly, but nitroglycerin containing impurities will decompose spontaneously, releasing large amounts of nitrogen oxide gas and heat, which in turn catalyzes the thermal decomposition of nitroglycerin. Therefore, neutralizers are added during the production process to improve the stability of explosives and propellants.

[0003] Currently, the primary stabilizer used in China is N,N-dimethyldiphenylurea (N,N-diethyldiphenylurea). The molecular structure of stabilizer No. 1 (N,N-diethyldiphenylurea) contains two ethyl groups attached to the nitrogen. This electronic effect is weaker than that of stabilizer No. 2, which contains a methyl group. Its electron cloud density is lower, and hydrogen bonding is less potent. Therefore, stabilizer No. 1 exhibits weaker intermolecular forces than stabilizer No. 2, resulting in a lower melting point and greater compatibility in product applications. However, the ethyl group in N-ethylaniline used in the synthesis of stabilizer No. 1 creates significant steric hindrance during the reaction, making its preparation difficult. This has hindered the widespread use of stabilizer No. 1. Summary of the Invention

[0004] In order to solve the problem of difficulty in preparing the No. 1 neutralizing agent in the prior art, the present invention proposes a preparation method of the No. 1 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. 1 medium-fixing agent 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 bis(trichloromethyl)carbonic acid to the N-ethylaniline mixture and stirring to react; during the reaction, controlling the addition rate of bis(trichloromethyl)carbonic acid 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 neutralizing agent No. 1.

[0010] Optionally, the pH of the alkaline aqueous solution in step 1) is 10-14; and the mass fraction of N-ethylaniline in the N-ethylaniline mixed solution is 25-30%.

[0011] Optionally, the duration of adding bis(trichloromethyl)carbonic acid to the N-ethylaniline mixture in step 2) is greater than 50 minutes.

[0012] Optionally, in the step 2), the weight ratio of the added trichloromethylcarbonic acid to the N-ethylaniline is controlled to be 0.49 to 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. When the residual amine content is lower than 0.2%, the reaction is terminated.

[0017] Optionally, in 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 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 and adopts a one-pot process to prepare a No. 1 neutralizing agent, and the preparation process is stable. The entire preparation process is safe and stable, and has little pollution during the entire reaction process.

[0023] When the solid triphosgene feed ratio is 120-125% of the theoretical value, the feeding time is extended to 50-60 minutes, 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 product 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-ethylanilinyl chloride, which is then condensed with N-ethylaniline to generate N,N-diethyldiphenylurea (neutralizer No. 1). The byproduct hydrogen chloride reacts with sodium hydroxide to generate sodium chloride and water.

[0025] Reaction mechanism:

[0026]

[0027] Reaction equation:

[0028] No. Ⅰ neutralizing agent

[0029]

[0030] Mother liquor:

[0031] HCl + NaOH → NaCl + H2O

[0032] Side effects:

[0033] Cl3CO-CO-OCCl3+12NaOH→3Na2CO3+6NaCl+6H2O

[0034] Test analysis methods

[0035] Residual amine detection method:

[0036] Take 1.0 g of crystals from the upper layer of the synthesis reactor, press dry the water with filter paper, weigh it on a balance (accurate to 0.01 g), then put it in a mortar and add 10 ml of hydrochloric acid to grind it. 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 blue spots appear on the starch potassium iodide test paper. The end point is that the spots do not disappear for 5 minutes. Record the number of milliliters titrated.

[0037] Calculate the residual amine content W1:

[0038]

[0039] Where:

[0040] w1——mass percentage of N-ethylaniline

[0041] v1——the number of milliliters of sodium nitrite solution consumed

[0042] c——molar concentration of sodium nitrite solution

[0043] 0.1212——milligram moles of N-ethylaniline

[0044] G——sample weight (g)

[0045] Yield calculation

[0046]

[0047] Where:

[0048] Yield (合成) ——Synthesis yield of crude ethyl neutralizer

[0049] m1——mass of crude ethyl neutralizer (g)

[0050] m2——Theoretical mass of ethyl neutralizer product (g)

[0051] M——Ethyl neutralizer molar mass (g / mol)

[0052]

[0053] Where:

[0054] Yield (精馏) ——Synthesis yield of crude ethyl neutralizer

[0055] m3——Product mass of ethyl neutralizer (g)

[0056] m4——mass of ethylene fraction (g)

[0057] m5——mass of crude ethyl neutralizer added (g)

[0058] Melting point test

[0059] Take a small amount of sample and grind it into the finest powder possible in a mortar. 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.

[0060] First, slowly raise the temperature of the heat transfer liquid to approximately 110°C, 10°C below the initial melting point range specified in the sample specifications. Attach the melting point tube containing the sample to the measuring thermometer, aligning the sample end of the melting point tube with the center of the mercury bulb. The mercury bulb should be located in the center of the heat transfer liquid. Maintain a steady heating rate of (1.0±0.1°C) / min. The temperature at which the sample shows obvious localized liquefaction is the initial melting temperature, and the temperature at which the sample is completely melted is the final melting temperature. Record the initial and final melting temperatures.

[0061] The melting point is the temperature from the initial melting point to the final melting point, and the final melting point minus the initial melting point is the melting range.

[0062] Example 1:

[0063] Sample synthesis:

[0064] (1) First, add 115.45g of water and 220.79g of 30% NaOH aqueous solution into the reactor, turn on the circulating water vacuum pump, start stirring, control the stirring speed at about 200 revolutions per minute, and then add 120.13g of N-ethylaniline.

[0065] (2) Slowly add solid granular bis(trichloromethyl)carbonate to the reactor. When oil is generated in the reactor, maintain the reaction state. After a period of time, sample the upper layer of oil and analyze the residual aromatic amine. During the reaction, vacuum is applied to maintain the relative pressure at -0.02 MPa.

[0066] (3) Based on the results of the in-process control analysis, if the product meets the standards, stirring is stopped and the subsequent stratification and water washing are carried out. If the standards are not met, bis(trichloromethyl)carbonate is continued to be added to carry out the synthesis reaction until the analysis results meet the standards. During the reaction, the highest temperature was 105.6°C, the amount of bis(trichloromethyl)carbonate used was 61.93g, and the addition duration was 54min.

[0067] (4) The reactor was cooled to 62.1°C in a water bath, and a solid sample was obtained after the system crystallized. The obtained product was filtered, washed with water, and then dried until it was substantially free of water.

[0068] (5) Record the product weight, crystal form, and appearance, and analyze the product amine residue, melting point, and melting range.

[0069] Examples 2 to 9

[0070] Adjust the reaction parameters as shown in Table 1.

[0071] Comparative Examples 1 and 2

[0072] Adjust the reaction parameters as shown in Table 1

[0073] Table 1 Main data of synthesis process

[0074]

[0075] Table 2 Synthesis experiment results

[0076] batch Appearance shape Gross weight (g) Net weight (g) Amine residual % 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

[0077] As shown in Tables 1 and 2, the ethyl group in N-ethylaniline creates significant steric hindrance, which can easily lead to incomplete reaction. To address this issue, the addition of solid triphosgene was slowed down and the heating mantle activated to allow for full reaction. Data show that this improved process significantly increases the yield of the intermediate No. 1, maintaining a stable yield above 96% with a 20-25% excess of solid triphosgene.

[0078] Due to the unique molecular structure of the stabilizer No. 1, its melting point is low, making sample isolation difficult. After the reaction, cooling in a water bath is required to crystallize the stabilizer No. 1 sample, resulting in a white solid. Therefore, the improved synthesis process for stabilizer No. 1 is stable, with a yield exceeding 96%, resulting in a high-quality, white powdery solid.

[0079] 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 water-soluble cooling crystallization to obtain the No. 1 intermediate fixer sample.

[0080] Examples 10 and 11

[0081] Vacuum distillation

[0082] (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.

[0083] (2) The crude product of the neutralizing agent is subjected to distillation treatment at 200°C-230°C. After the distilled sample becomes a colorless transparent liquid, it is collected into a finished product bottle to obtain a refined neutralizing agent finished product.

[0084] (3) Record the weight of the finished product and analyze the product, amine residue in the fore fraction, melting point, and melting range.

[0085] Comparative Examples 3 and 4

[0086] The temperature and pressure of the vacuum distillation were adjusted as shown in Table 1.

[0087] Table 3 Distillation experimental results

[0088] Serial number Temperature (℃) Pressure (MPa) Amine residual % Yield % Melting range (℃) Example 10 203 -0.96 0.01 97.6 71-72.5 Example 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

[0089] 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 of more 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 residue and organic high-boiling substances, which is easy to handle without the risk of explosion.

[0090] 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 performance of the product after distillation is significantly greater than the national indicators.

[0091] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing a No. 1 medium fixative, characterized in that: The steps include: The method comprises the following steps: adding N-ethylaniline to an alkaline aqueous solution and mixing the mixture to obtain an N-ethylaniline mixed solution; wherein the pH of the alkaline aqueous solution is 10 to 14; and the mass fraction of N-ethylaniline in the N-ethylaniline mixed solution is 25 to 30%. The method comprises the following steps: adding solid granular bistrichloromethyl carbonate to the N-ethylaniline mixed solution and stirring the mixture to react; controlling the addition rate of the bistrichloromethyl carbonate to maintain the reaction temperature below 110° C. during the reaction to obtain a reaction product; and controlling the weight ratio of the added trichloromethyl carbonate to the N-ethylaniline to be 0.49 to 0.52:

1. Step 3) The reaction product is subjected to solid-liquid separation to obtain a No. 1 neutralizing agent.

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

3. The preparation method of No. 1 medium fixative according to claim 1, wherein In the step 2), the stirring rate is controlled to be 200-400 r / min.

4. The preparation method of 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.

5. The preparation method of No. 1 medium fixative according to claim 1, wherein 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 lower than 0.2%, the reaction is terminated.

6. The preparation method of No. 1 medium fixative according to claim 1, wherein 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.

1.

7. The preparation method of No. 1 medium fixative according to claim 1, wherein The method further comprises: Step 4) The No. 1 intermediate agent in step 3) is subjected to vacuum distillation to obtain a refined No. 1 intermediate agent.

8. The preparation method of No. 1 medium fixative according to claim 7, wherein The relative pressure during the vacuum distillation process is lower than -0.09 MPa and the temperature is 200°C to 230°C.

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