Synthesis method of non-explosive picrate

Abstract

The present invention discloses a non-explosive picrate synthesis method, and relates to the technical field of chemical synthesis, the method selects picric acid, aromatic hydrocarbon, aromatic ether and the like as raw materials, and low alcohol or aromatic hydrocarbon is matched as a solvent. The synthesis method comprises an alcohol co-dissolution method, an azeotropic dehydration method and a mixed solvent method, and picrate is prepared through the operations of dissolution, mixing, cooling crystallization and the like. And reacting the product with raw materials, filtering, washing and drying to obtain the final product. According to the method, explosive dry picric acid is replaced by safe raw materials, so that the explosion risk is effectively reduced; reaction conditions are accurately controlled, and the product stability is improved; the reaction process is optimized, the reaction time is shortened, the synthesis efficiency is improved, the method is suitable for industrial large-scale production, and the prepared picrate has wide application prospects in the fields of fuel additives, medical intermediates and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and specifically to a method for synthesizing non-explosive picrates. Background Art

[0002] Since the 1940s, ferrous picrate / picrate-based fuel additives have been widely used in the technical field, and the research on the preparation of related picrates has also attracted much attention. Traditional methods often use dry picric acid as a raw material, but dry picric acid is a high explosive with a sensitivity exceeding that of TNT, posing great safety hazards during production, storage, and transportation, which limits its industrial application. Some existing methods for preparing picrates, such as the direct iron-picric acid reaction, require a relatively high moisture content to maintain the reaction rate. However, moisture will accelerate the deterioration of the product, and the product quality is unstable. In addition, some processes are complex and costly, making it difficult to meet the requirements of large-scale production. Therefore, it is urgent to develop a safe, efficient, and stable method for synthesizing non-explosive picrates.

[0003] In view of this, the present application is specifically proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for synthesizing non-explosive picrates to solve the problems mentioned in the above background art.

[0005] To solve the above technical problems, the method for synthesizing non-explosive picrates provided by the present invention includes the following steps:

[0006] Step 1: Prepare raw materials: Select at least one of picric acid, aromatic hydrocarbons, and aromatic ethers as reaction raw materials, and ensure that the purity of the raw materials meets the reaction requirements; prepare a solvent for dissolving the raw materials, including at least one of lower alcohols and aromatic hydrocarbons; the product of this step is the reaction raw materials and solvent that meet the purity requirements, obtaining product 1.

[0007] Step 2: Select a synthesis method: Select one of the following methods for synthesis:

[0008] Alcohol co-solubility method: Dissolve picric acid in boiling lower alcohol to form an alcohol solution of picric acid, which is product 2-1; add hot aromatic hydrocarbon to make the two fully mixed to obtain a mixed solution, denoted as product 3-1; cool the mixed solution to precipitate picrate crystals, and this crystalline product is denoted as product 4-1.

[0009] Azeotropic dehydration method: Dissolve picric acid in aromatic hydrocarbon to obtain an aromatic hydrocarbon solution of picric acid, denoted as product 2-2; heat to the azeotropic state to remove water, obtaining the solution after water removal, denoted as product 3-2; cool the solution after azeotropy to separate out picrate, which is product 4-2.

[0010] Mixed solvent method: Picric acid and solid aromatic hydrocarbon / ether are respectively dissolved in a hot solvent to obtain a hot solution of picric acid and a hot solution of solid aromatic hydrocarbon / ether, which are respectively denoted as product 2-3 and product 3-3; the two hot solutions are mixed evenly to obtain a mixed solution, denoted as product 4-3; the mixed solution is cooled to crystallize picrate, and the crystalline product is denoted as product 5-3.

[0011] Step 3: Final product: React one of the final products (i.e., product 4-1 or product 4-2 or product 5-3) in Step 2 with product 1; after the reaction is completed, filter the reaction product to remove impurities in the solution to obtain a preliminarily purified product, denoted as product 6; wash the filtered product with a suitable solvent to improve the purity to obtain a washed product, denoted as product 7; dry the washed product to obtain a dry non-explosive picrate product, denoted as product 8.

[0012] Further, in Step 1, the aromatic hydrocarbon is one or more of benzene, toluene, xylene, naphthalene, anthracene, and pyrene; the aromatic ether is one or more of anisole, diphenyl ether, phenetole, 1,3-

[0013] dimethoxybenzene, benzyl ether, and veratrole.

[0014] Further, in Step 1, the lower alcohol is one or more of methanol, ethanol, and propanol.

[0015] Further, in Step 2, in the alcohol co-solvent method, the dissolution temperature of picric acid in boiling lower alcohol is 60-90 °C, and when adding hot aromatic hydrocarbon, the temperature of the aromatic hydrocarbon is maintained at 50-80 °C.

[0016] Further, in Step 2, in the azeotropic dehydration method, after picric acid is dissolved in the aromatic hydrocarbon, the azeotropic temperature is 80-120 °C, and the azeotropic time is 1-3 hours.

[0017] Further, in Step 2, in the mixed solvent method, the temperature of the hot solvent in which picric acid and solid aromatic hydrocarbon / ether are respectively dissolved is 70-100 °C, and the cooling rate of the mixed solution after mixing is 5-10 °C / minute.

[0018] Further, in Step 3, the reaction temperature between the final product in Step 2 and product 1 is 20-60 °C, and the reaction time is 1-3 hours; the pore size of the filter membrane used for filtration is 0.1-1 micron.

[0019] Further, in Step 3, the solvent used for washing is at least one of the same lower alcohol and aromatic hydrocarbon as in the synthesis process; the drying temperature is 40-60 °C, and the drying time is 2-6 hours.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. By enhancing safety: Replacing dry picric acid with non-explosive reaction raw materials eliminates friction or impact sensitivity at the source, greatly reducing the explosion risk and ensuring the safety of personnel and equipment during production, storage, and transportation.

[0022] 2. Enhancing product stability: By precisely controlling reaction conditions such as temperature, solvent, etc., factors causing product deterioration are effectively reduced. The synthesized picrate salts show significantly improved stability during storage, reducing economic losses due to product deterioration and extending the product's service life.

[0023] 3. Improving synthesis efficiency: The optimized reaction conditions greatly shorten the reaction time. For example, under specific temperature and stirring conditions, the reaction can be completed in a shorter time. At the same time, selecting appropriate solvents and reaction methods increases the conversion rate of raw materials, improves production efficiency, reduces production costs, and is more suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a flow chart of the synthesis method of non-explosive picrate salts. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Please refer to Figure 1 , the present invention provides a technical solution: a synthesis method of non-explosive picrate salts, including:

[0027] Example 1: Synthesis of phenyl picrate by alcohol co-solvent method:

[0028] (1) Prepare raw materials

[0029] Precisely weigh 10 g of picric acid to ensure its purity is over 99%. Prepare 50 mL of anhydrous methanol as the lower alcohol for dissolving picric acid, and 50 mL of benzene as the aromatic hydrocarbon. Also prepare anhydrous methanol for subsequent washing and equipment such as an oven for drying. After these raw materials and equipment are prepared, reaction raw materials and solvents meeting the purity requirements are obtained, denoted as Product 1.

[0030] (2) Alcohol co-solvent reaction

[0031] Slowly add 10 g of picric acid to 50 mL of boiling anhydrous methanol, and continuously stir until the picric acid is completely dissolved to prepare an alcoholic solution of picric acid, which is the product 2-1. Heat 50 mL of benzene to 70 °C, and then slowly add it to the methanol solution of picric acid, and mix well to obtain a mixed solution, denoted as product 3-1. Naturally cool the mixed solution to room temperature, and during this process, light yellow needle-like crystals gradually precipitate. After cooling is completed, a crystalline product, namely phenyl picrate, is obtained, denoted as product 4-1.

[0032] (3) Post-treatment

[0033] Filter the mixed solution containing phenyl picrate crystals using a filter membrane with a pore size of 0.5 microns to separate the crystals from the solution and remove impurities in the solution to obtain preliminarily purified phenyl picrate, denoted as product 6. Wash product 6 with 50 mL of anhydrous methanol, wash 3 times, filter after soaking for 5 minutes each time to improve the purity, and obtain the washed phenyl picrate, denoted as product 7. Place product 7 in an oven at 45 °C and dry for 3 hours to obtain a dry phenyl picrate product, denoted as product 8.

[0034] (4) React with product 1

[0035] Add the dried phenyl picrate (product 8) and the remaining raw materials prepared in step (1) (part of the raw materials in product 1, such as benzene and methanol that did not participate in the synthesis reaction, and react according to the molar ratio of phenyl picrate to benzene and methanol of 1:2:5) to a reaction vessel, and stir and react at 30 °C for 2 hours. After the reaction is completed, perform subsequent treatment to obtain the final non-explosive picrate product.

[0036] Example 2: Synthesis of naphthyl picrate by azeotropic dehydration method:

[0037] (1) Prepare raw materials

[0038] Weigh 15 g of picric acid with a purity of not less than 98%. Prepare 100 mL of toluene as an aromatic hydrocarbon solvent, and at the same time prepare experimental equipment such as an azeotropic device and a condenser. Obtain reaction raw materials and solvents that meet the purity requirements, denoted as product 1.

[0039] (2) Azeotropic dehydration reaction

[0040] Add 15 g of picric acid to 100 mL of toluene, stir to dissolve it completely to obtain a toluene solution of picric acid, denoted as product 2-2. Transfer the solution to an azeotropic device, heat to 110 °C for azeotropic dehydration, and the azeotropic time is 2 hours. During this process, continuously distill out toluene vapor containing water, and separate the water after condensation through a condenser to obtain a dehydrated solution, denoted as product 3-2. Cool the azeotropic solution to room temperature, and yellow needle-like crystals precipitate. Separate the crystals, namely naphthyl picrate, denoted as product 4-2.

[0041] (3) Post-treatment

[0042] Filter the picrate of naphthalene with a filter membrane with a pore size of 0.3 μm to remove impurities, and obtain the preliminarily purified picrate of naphthalene, denoted as Product 6. Wash Product 6 with 30 mL of toluene twice, filter after soaking for 8 minutes each time, and obtain the washed picrate of naphthalene, denoted as Product 7. Place Product 7 in an oven at 50 °C and dry for 4 hours to obtain the dried picrate of naphthalene product, denoted as Product 8.

[0043] (4) React with Product 1

[0044] Add the dried picrate of naphthalene (Product 8) and the remaining toluene in step (1) (the toluene in Product 1, and react according to the molar ratio of picrate of naphthalene to toluene of 1:3) to a reaction vessel, and stir and react at 40 °C for 1.5 hours. After the reaction, carry out subsequent treatment to obtain the final non-explosive picrate product.

[0045] Example 3: Synthesis of anisole picrate by the mixed solvent method:

[0046] (1) Prepare raw materials

[0047] Weigh 8 g of picric acid to ensure a purity of about 99%. Prepare 30 mL of absolute ethanol as the solvent for dissolving picric acid, 20 mL of anisole as the aromatic ether, and an appropriate amount of a hot bath device, etc. Obtain the reaction raw materials and solvents that meet the purity requirements, denoted as Product 1.

[0048] (2) React in the mixed solvent

[0049] Add 8 g of picric acid to 30 mL of absolute ethanol heated to 80 °C, stir until completely dissolved to obtain a hot solution of picric acid, denoted as Product 2-3. Heat 20 mL of anisole to 85 °C to make it a hot anisole solution, denoted as Product 3-3. Mix the ethanol solution of picric acid and the hot anisole solution evenly to obtain a mixed solution, denoted as Product 4-3. Cool the mixed solution, control the cooling rate at 8 °C / minute, and yellow crystals gradually precipitate to obtain the crystalline product, that is, anisole picrate, denoted as Product 5-3.

[0050] (3) Post-treatment

[0051] Filter the solution containing anisole picrate crystals with a filter membrane with a pore size of 0.8 μm to separate the crystals, and obtain the preliminarily purified anisole picrate, denoted as Product 6. Wash Product 6 with 20 mL of absolute ethanol three times, filter after soaking for 6 minutes each time, and obtain the washed anisole picrate, denoted as Product 7. Place Product 7 in an oven at 40 °C and dry for 5 hours to obtain the dried anisole picrate product, denoted as Product 8.

[0052] (4) React with Product 1

[0053] Add the dried anisole picrate (Product 8), the remaining absolute ethanol and anisole in Step (1) (partial raw materials in Product 1, reacting according to the molar ratio of anisole picrate to absolute ethanol and anisole of 1:1.5:2) into the reaction vessel, and stir and react at 25 °C for 2.5 hours. After the reaction is completed, carry out subsequent treatment to obtain the final non-explosive picrate product.

[0054] In summary, in the present invention, by using picric acid, aromatic hydrocarbons, aromatic ethers, etc. as raw materials and selecting the alcohol co-solvent method, azeotropic dehydration method, and mixed solvent method for synthesis reactions, the function of preparing non-explosive picrates is realized. By controlling parameters such as the temperature, time, and raw material ratio of each reaction step, such as controlling the dissolution temperature and the aromatic hydrocarbon addition temperature in the alcohol co-solvent method, controlling the azeotropic temperature and time in the azeotropic dehydration method, and controlling the dissolution temperature and cooling rate in the mixed solvent method, the function of precisely synthesizing picrates with specific structures and properties is realized. By filtering, washing, and drying the reaction products and further reacting them with the raw materials, the functions of improving the product purity and optimizing the product performance to meet the requirements of different application scenarios are realized.

Claims

1. A method for synthesizing non-explosive picrates, characterized in that: It includes the following steps: Step 1: Prepare raw materials: Select at least one of picric acid, aromatic hydrocarbons, and aromatic ethers as the reaction raw materials; Prepare a solvent for dissolving the raw materials, including at least one of lower alcohols and aromatic hydrocarbons; obtain Product 1; Step 2: Select a synthesis method: Select one of the following methods for synthesis: Alcohol co-solubility method: Dissolve picric acid in boiling lower alcohol to form an alcohol solution of picric acid, which is Product 2-1; add hot aromatic hydrocarbon to make the two fully mixed to obtain a mixed solution, denoted as Product 3-1; cool the mixed solution to precipitate picrate crystals, and this crystalline product is denoted as Product 4-1; Azeotropic dehydration method: Dissolve picric acid in aromatic hydrocarbon to obtain an aromatic hydrocarbon solution of picric acid, denoted as Product 2-2; heat to the azeotropic state to remove water to obtain the dehydrated solution, denoted as Product 3- 2; cool the azeotropic solution to separate out picrate, which is Product 4-2; Mixed solvent method: Dissolve picric acid and solid aromatic hydrocarbon / ether in hot solvent respectively to obtain a hot solution of picric acid and a hot solution of solid aromatic hydrocarbon / ether, denoted as Product 2-3 and Product 3- 3 respectively; mix the two hot solutions evenly to obtain a mixed solution, denoted as Product 4- 3; cool the mixed solution to precipitate picrate crystals, and this crystalline product is denoted as Product 5-3; Step 3: Final product: React one of the final products in Step 2 with Product 1; after the reaction is completed, filter the reaction product to remove impurities in the solution to obtain a preliminarily purified product, denoted as Product 6; wash the filtered product with a suitable solvent to improve the purity to obtain a washed product, denoted as Product 7; dry the washed product to obtain a dry non-explosive picrate product, denoted as Product 8.

2. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 1, the aromatic hydrocarbon is one or more of benzene, toluene, xylene, naphthalene, anthracene, and pyrene; the aromatic ether is one or more of anisole, diphenyl ether, phenetole, 1,3- dimethoxybenzene, benzyl ether, and veratrole.

3. The synthetic method of non-explosive picrate according to claim 1, characterized in that: In the above Step 1, the lower alcohol is one or more of methanol, ethanol, and propanol.

4. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 2, in the alcohol co-solubility method, the dissolution temperature of picric acid in boiling lower alcohol is 60-90°C, and when adding hot aromatic hydrocarbon, the temperature of the aromatic hydrocarbon is maintained at 50-80°C.

5. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 2, in the azeotropic dehydration method, after picric acid is dissolved in aromatic hydrocarbon, the azeotropic temperature is 80- 120°C, and the azeotropic time is 1-3 hours.

6. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 2, in the mixed solvent method, the temperature of the hot solvent for dissolving picric acid and solid aromatic hydrocarbon / ether respectively is 70-100°C, and the cooling rate of the mixed solution after mixing is 5-10°C per minute.

7. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 3, the reaction temperature between the final product in Step 2 and Product 1 is 20-60°C, and the reaction time is 1-3 hours; the pore size of the filter membrane used for filtration is 0.1-1 micron.

8. The synthesis method of the non-explosive picrate according to claim 1, characterized in that: In the above Step 3, the solvent used for washing is at least one of the same lower alcohols and aromatic hydrocarbons as in the synthesis process; the drying temperature is 40-60°C, and the drying time is 2-6 hours.

Images