Chlorine-free synthesis method of 2, 4-dinitroanisole

Abstract

The invention discloses a chlorine-free synthesis method of 2, 4-dinitroanisole. The method comprises the following steps: by taking phenol as a raw material, carrying out first-stage and second-stage nitration in a microchannel or a tubular reactor to obtain 2, 4-dinitrophenol, then carrying out alkylation reaction on the 2, 4-dinitrophenol and an alkylation reagent under the action of an acid-binding agent, and carrying out filtration, rotary evaporation, precipitation, filtration, water washing and the like on a reaction solution to obtain a DNAN solid. According to the synthesis method, phenol is used as a raw material instead of chlorobenzene in a traditional process, chloride ions are not involved in the preparation process, corrosion to equipment is reduced, meanwhile, generation of a large amount of waste acid is avoided, and the three-waste treatment cost is reduced.

Description

Technical Field

[0001] The invention relates to the field of energetic material synthesis, and in particular to a chlorine-free synthesis method of 2,4-dinitroanisole. Background Art

[0002] 2,4-Dinitroanisole (DNAN) is a new type of melt-cast explosive with the advantages of high energy, high stability and high density, and is considered to be the most promising alternative to 2,4,6-trinitrotoluene (TNT). In addition, DNAN is also an important intermediate used to synthesize red-based RC (2-methoxy-5-nitroaniline hydrochloride) in the field of dye synthesis, and can be used as an insecticide with significant effects on a variety of insects in the agricultural field.

[0003]

[0004] The commonly used method at present is to nitrate chlorobenzene in a mixed acid of nitric acid and sulfuric acid to prepare 1-chloro-2,4-dinitrobenzene (CDB). CDB undergoes nucleophilic substitution with methanol under alkaline conditions to obtain DNAN. This process uses sulfuric acid and nitric acid as nitrating agents, and a large amount of waste acid is generated during the production process, which is difficult to recycle. Due to the use of chlorobenzene, chloride ions will corrode the equipment during the production process. The use of high-concentration sodium hydroxide will also produce a large amount of chlorine-containing wastewater, causing environmental pollution problems, and greatly increasing post-processing and production costs. Chloride ions exist in the DNAN produced by the chlorobenzene process, which corrodes the shell of the charge and affects the safety of DNAN as a melt-cast carrier explosive.

[0005] Traditional synthesis processes are mostly carried out in batch reactors with large online volumes. The nitration reaction is an exothermic reaction, and there are a large number of energetic materials in the reaction system. If the reaction process gets out of control, the local temperature rise in the reactor will cause the decomposition of nitric acid and DNAN, produce toxic gases such as NO2, and even cause explosions, posing major safety hazards. In addition, a large amount of methanol solvent accumulates in the reaction system. The boiling point of methanol is close to the reaction temperature. If the reaction temperature rises, the methanol boils and the liquid level rises, leading to overflow events. Summary of the invention

[0006] In view of the problems of strong corrosiveness and large amount of waste acid in the DNAN synthesis method using chlorobenzene as raw material, the present invention proposes a chlorine-free synthesis method of 2,4-dinitroanisole (DNAN). The method uses phenol as raw material and prepares DNAN through two-stage nitration and alkylation reactions. The treatment of a large amount of waste acid and chlorine-containing wastewater in the production process is avoided, and the production and treatment costs are greatly reduced. At the same time, a microchannel reactor is used for nitration reaction, which shortens the reaction time and improves the safety and production efficiency of the reaction.

[0007] To solve the above problems, the technical solution of the present invention is: a chlorine-free synthesis method of 2,4-dinitroanisole, comprising the following steps:

[0008] (1) Phenol and a solvent are mixed in proportion to form a raw material liquid, the raw material liquid and concentrated nitric acid are introduced into a microchannel or tubular reactor in proportion at the same time, and the mixture is kept warm in an extension tube for a period of time, and purified by distillation to obtain purified 4-nitrophenol;

[0009] (2) 4-nitrophenol and a solvent are mixed in proportion as a raw material liquid for the second stage nitration, the raw material liquid and concentrated nitric acid are continuously introduced into a microchannel reactor in proportion at the same time, and then connected to a pipeline for heat preservation reaction to obtain a 2,4-dinitrophenol (2,4-DNP) reaction liquid, which is then added to water after cooling, filtered, and washed with water to obtain 2,4-DNP as a raw material for the next step of alkylation;

[0010] (3) 2,4-DNP and solvent are added to a reaction kettle in proportion and the temperature is raised while maintaining reflux. A certain proportion of an acid-binding agent and a catalyst are added to the reaction kettle. An alkylating agent is introduced into the reactor and the temperature is kept high until the reaction is complete to obtain a DNAN reaction solution. The reaction solution is cooled and filtered. The filtrate is added to water after rotary evaporation to precipitate. The target product DNAN is obtained after filtering and washing.

[0011] Furthermore, in step (1), the solvent is any one of N-methylpyrrolidone, acetonitrile, and 1,4-dioxane, and the molar ratio of phenol to the solvent is 1:1 to 6.

[0012] Furthermore, in step (1), the molar ratio of phenol to concentrated nitric acid is 1:1-6, the reaction temperature is 10-30° C., and the reaction residence time is 1-30 min.

[0013] Furthermore, in step (2), the molar ratio of 4-nitrophenol to concentrated nitric acid is 1:1-6, the reaction temperature is 50-90° C., and the reaction residence time is 5-70 min.

[0014] Furthermore, in step (3), the solvent is any one of dimethyl sulfoxide, N-methylpyrrolidone, and acetone, the acid binding agent is sodium carbonate or potassium carbonate, the catalyst is polyethylene glycol 400 or hexadecyl ammonium bromide, and the alkylating agent is any one of trimethyl orthoformate, dimethyl sulfate, and dimethyl carbonate, preferably dimethyl sulfate.

[0015] Furthermore, in step (3), the molar ratio of 2,4-dinitrophenol, acid binding agent, catalyst and alkylating agent is 1:1-5:1-5:1-10, the reaction temperature is 30-70°C, and the reaction time is 5-120 min.

[0016] Compared with the traditional chlorobenzene synthesis method, the present invention has the following significant advantages: (1) phenol is used instead of chlorobenzene as the raw material, thereby avoiding the corrosion of production equipment and charge shells by chloride ions. (2) nitric acid is used instead of nitric and sulfuric acid mixed acid as the nitrating agent, thereby avoiding the treatment of a large amount of waste acid and greatly reducing the post-treatment cost. (3) microchannel and tubular reactors are used, the online amount is small, the reaction time is greatly shortened, and the safety and production efficiency of the system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure is a flow chart of the chlorine-free synthesis method of 2,4-dinitroanisole (DNAN).

[0018] Figure 2 This is a comparison chart of the HPLC test results of the synthesized DNAN reaction solution and the standard sample.

[0019] Figure 3 For DNAN 1 H NMR spectrum. DETAILED DESCRIPTION

[0020] The invention is further described below by way of examples, but the invention is not limited by the following examples.

[0021] Combination Figure 1 The present invention provides a chlorine-free synthesis process flow chart of 2,4-dinitroanisole (DNAN). Meanwhile, the synthesis route of DNAN of the present invention is as follows:

[0022]

[0023] Example 1:

[0024] The synthetic method of this example 4-nitrophenol comprises the following steps:

[0025] Prepare 2g phenol and 20mL N-methylpyrrolidone at room temperature, and weigh 5mL concentrated nitric acid in a syringe. Adjust the flow rate of the injection pump according to the molar ratio of phenol to concentrated nitric acid of 1:1.2, and pump it into the microchannel reactor at the same time. Connect the extension tube to the microchannel reactor and place it in a thermostatic bath for insulation. The reaction residence time is 20min and the insulation temperature is 13°C. After the reaction, cool the 4-nitrophenol reaction liquid, separate by distillation, precipitate, filter, and wash with water to obtain pure 4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the phenol conversion rate is 92% and the 4-nitrophenol yield is 56.3%.

[0026] Example 2:

[0027] The synthetic method of this example 4-nitrophenol comprises the following steps:

[0028] Prepare 2g phenol and 20mL acetonitrile at room temperature, and weigh 5mL concentrated nitric acid in a syringe. According to the molar ratio of phenol to concentrated nitric acid of 1:1.2, adjust the flow rate ratio of the injection pump to 11.1:1, and pump the two routes into the microchannel reactor at the same time. Connect the extension tube after the microchannel reactor and place it in a constant temperature bath for insulation. The reaction residence time is 20min and the insulation temperature is 13°C. After the reaction, the 4-nitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the phenol conversion rate is 98% and the 4-nitrophenol yield is 43.2%.

[0029] Example 3:

[0030] The synthetic method of this example 4-nitrophenol comprises the following steps:

[0031] Prepare 2g phenol and 20mL 1,4-dioxane at room temperature, and weigh 5mL concentrated nitric acid in a syringe. According to the molar ratio of phenol to concentrated nitric acid of 1:1.8, adjust the flow rate ratio of the injection pump to 7.4:1, and pump the two channels into the microchannel reactor at the same time. The microchannel reactor is connected to an extension tube and placed in a constant temperature bath for insulation. The reaction residence time is 20min and the insulation temperature is 13°C. After the reaction, the 4-nitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the phenol conversion rate is 96.9% and the 4-nitrophenol yield is 70.2%.

[0032] Example 4:

[0033] The synthetic method of this example 4-nitrophenol comprises the following steps:

[0034] Prepare 2g phenol and 20mL 1,4-dioxane at room temperature, and weigh 5mL concentrated nitric acid in a syringe. According to the molar ratio of phenol to concentrated nitric acid of 1:1.8, adjust the flow rate ratio of the injection pump to 7.4:1, and pump the two channels into the microchannel reactor at the same time. The microchannel reactor is connected to an extension tube and placed in a constant temperature bath for insulation. The reaction residence time is 8min and the insulation temperature is 19°C. After the reaction, the 4-nitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the phenol conversion rate is 98.2% and the 4-nitrophenol yield is 69.7%.

[0035] Example 5:

[0036] The synthetic method of this example 4-nitrophenol comprises the following steps:

[0037] Prepare 2g phenol and 20mL 1,4-dioxane at room temperature, and weigh 5mL concentrated nitric acid in a syringe. According to the molar ratio of phenol to concentrated nitric acid of 1:1.8, adjust the flow rate ratio of the injection pump to 7.4:1, and pump the two channels into the microchannel reactor at the same time. The microchannel reactor is connected to an extension tube and placed in a constant temperature bath for insulation. The reaction residence time is 8min and the insulation temperature is 16°C. After the reaction, the 4-nitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the phenol conversion rate is 98.2% and the 4-nitrophenol yield is 70.2%.

[0038] Example 6:

[0039] The synthetic method of 2,4-dinitrophenol (2,4-DNP) in this example comprises the following steps:

[0040] Prepare 2g of 4-nitrophenol and 20mL of N-methylpyrrolidone at room temperature, and weigh 5mL of concentrated nitric acid into a syringe. Adjust the flow rate of the injection pump according to the molar ratio of phenol to concentrated nitric acid of 1:1.5, and pump the two channels into the microchannel reactor at the same time. Connect the extension tube after the microchannel reactor and place it in a constant temperature bath for insulation. The reaction residence time is 60min and the insulation temperature is 70°C. After the reaction, the 2,4-dinitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 2,4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the conversion rate of 4-nitrophenol is 97.8%, and the yield of 2,4-dinitrophenol is 92.5%.

[0041] Example 7:

[0042] The synthetic method of 2,4-dinitrophenol (2,4-DNP) in this example comprises the following steps:

[0043] Prepare 2g of 4-nitrophenol and 20mL of N-methylpyrrolidone at room temperature, and weigh 5mL of concentrated nitric acid in a syringe. Adjust the flow rate of the injection pump according to the molar ratio of phenol to concentrated nitric acid of 1:2, and pump the two channels into the microchannel reactor at the same time. Connect the extension tube after the microchannel reactor and place it in a constant temperature bath for insulation. The reaction residence time is 60min and the insulation temperature is 70°C. After the reaction, the 2,4-dinitrophenol reaction liquid is cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 2,4-dinitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the conversion rate of 4-nitrophenol is 99.8%, and the yield of 2,4-dinitrophenol is 97.2%.

[0044] Example 8:

[0045] The synthetic method of 2,4-dinitrophenol (2,4-DNP) in this example comprises the following steps:

[0046] Prepare 2g of 4-nitrophenol and 20mL of 1,4-dioxane at room temperature, and weigh 5mL of concentrated nitric acid in a syringe. Adjust the flow rate of the syringe pump according to the molar ratio of phenol to concentrated nitric acid of 1:2, and pump both into the microchannel reactor at the same time. Connect the extension tube to the microchannel reactor and place it in a thermostatic bath for insulation. The reaction residence time is 15min and the insulation temperature is 80°C. After the reaction, cool the 2,4-dinitrophenol reaction liquid, separate by distillation, precipitate, filter, and wash with water to obtain pure 2,4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the conversion rate of 4-nitrophenol is 99.5%, and the yield of 2,4-dinitrophenol is 97.2%.

[0047] Example 9:

[0048] The synthetic method of 2,4-dinitrophenol (2,4-DNP) in this example comprises the following steps:

[0049] 2g of 4-nitrophenol and 20mL of 1,4-dioxane were prepared at room temperature, and 5mL of concentrated nitric acid was weighed into the syringe. The flow rate of the injection pump was adjusted according to the molar ratio of phenol to concentrated nitric acid of 1:2, and the two channels were pumped into the microchannel reactor at the same time. The microchannel reactor was connected to an extension tube and placed in a constant temperature bath for insulation. The reaction residence time was 5min and the insulation temperature was 80°C. After the reaction, the 2,4-dinitrophenol reaction liquid was cooled, distilled, separated, precipitated, filtered, and washed with water to obtain pure 2,4-nitrophenol as the raw material for the second nitration reaction. After high performance liquid chromatography analysis, the conversion rate of 4-nitrophenol was 80.8%, and the yield of 2,4-dinitrophenol was 81.1%.

[0050] Example 10:

[0051] The synthetic method of 2,4-dinitroanisole (DNAN) in this example comprises the following steps:

[0052] Prepare 1.5g of 2,4-DNP and 20mL of trimethyl orthoformate at room temperature, add them into the reaction kettle and heat to 90°C. Keep warm for 1h to obtain DNAN reaction solution. The reaction solution and DNAN standard sample are analyzed by liquid chromatography at the same time. The comparison results are shown in Figure 2 The DNAN reaction solution was cooled and filtered to separate the catalyst. The filtrate was added to water for precipitation after rotary evaporation. The target product DNAN was obtained after filtration and washing. Liquid chromatography analysis showed that the conversion rate of 2,4-DNP was 23% and the yield of DNAN was 15%.

[0053] Example 11:

[0054] The synthetic method of 2,4-dinitroanisole (DNAN) in this example comprises the following steps:

[0055] 1.5 g 2,4-DNP and 20 mL dimethyl carbonate were prepared at room temperature, added to a reaction kettle and heated to 90°C, sodium carbonate was added thereto, and the reaction mixture was kept warm for 1 hour to obtain a DNAN reaction solution. The DNAN reaction solution was cooled and filtered to separate the catalyst, and the filtrate was added to water for precipitation after rotary evaporation, and the target product DNAN was obtained after filtration and washing. Liquid chromatography analysis showed that the conversion rate of 2,4-DNP was 35% and the yield of DNAN was 27%.

[0056] Example 12:

[0057] The synthetic method of 2,4-dinitroanisole (DNAN) in this example comprises the following steps:

[0058] 1.5g 2,4-DNP and 20mL dimethyl sulfoxide were prepared at room temperature, added to the reactor and heated to 90°C. The solution was slightly boiled and kept under reflux. 1.7g potassium carbonate and 2g polyethylene glycol 400 were added to the reactor as catalysts. Finally, 2.3mL dimethyl sulfate was introduced into the reactor using a syringe pump, and the reaction mixture was kept warm for 1h until the reaction was complete to obtain a DNAN reaction solution. After cooling the DNAN reaction solution, the catalyst was separated by filtration. The filtrate was added to water after rotary evaporation to precipitate. The target product DNAN was obtained after filtration and washing. Liquid chromatography analysis showed that the conversion rate of 2,4-DNP was 78%, the yield of DNAN was 81%, and the purity was 99.2%.

[0059] Example 13:

[0060] The synthetic method of 2,4-dinitroanisole (DNAN) in this example comprises the following steps:

[0061] Prepare 1.5g 2,4-DNP and 20mL acetone at room temperature, add them to the reactor and heat to 57°C. The solution is slightly boiling and kept under reflux. Add 1.7g potassium carbonate and 3.5g hexadecyltrimethylammonium bromide as catalysts to the reactor. Finally, use a syringe pump to pass 2.3mL of dimethyl sulfate into the reactor and keep warm for 1h until the reaction is complete to obtain a DNAN reaction solution. After cooling the DNAN reaction solution, filter and separate the catalyst. The filtrate is added to water after rotary evaporation to precipitate. After filtering and washing, the target product DNAN can be obtained. Liquid chromatography analysis showed that the conversion rate of 2,4-DNP was 99.1%, the yield of DNAN was 90%, and the purity was 99.2%. The hydrogen spectrum of DNAN is shown in Figure 3 .

[0062] Example 14:

[0063] The synthetic method of 2,4-dinitroanisole (DNAN) in this example comprises the following steps:

[0064] 1.5g 2,4-DNP and 20mL acetone were prepared at room temperature, added to the reactor and heated to 57°C. The solution was slightly boiled and kept under reflux. 1.7g ethylenediamine and 3.5g polyethylene glycol 400 were added to the reactor as catalysts. Finally, 2.3mL dimethyl sulfate was introduced into the reactor using a syringe pump, and the reaction mixture was kept warm for 1h until the reaction was complete to obtain a DNAN reaction solution. After cooling the DNAN reaction solution, the catalyst was separated by filtration. The filtrate was added to water after rotary evaporation to precipitate. The target product DNAN was obtained after filtration and washing. Liquid chromatography analysis showed that the conversion rate of 2,4-DNP was 64%, the yield of DNAN was 51%, and the purity was 98.3%.

Claims

1. A chlorine-free synthesis method of 2,4-dinitroanisole, characterized in that: The steps include: (1) Phenol and a solvent are mixed in proportion as a raw material liquid, the raw material liquid and concentrated nitric acid are introduced into a microchannel or tubular reactor in proportion at the same time, and the temperature is kept in an extended tube for a period of time, and purified by distillation to obtain purified 4-nitrophenol; (2) 4-nitrophenol and a solvent are mixed in proportion as a raw material liquid for the second stage of nitration, and the raw material liquid and concentrated nitric acid are introduced into a microchannel reactor in proportion at the same time, and then connected to a pipeline for heat preservation reaction, and then added to water after cooling, and 2,4-DNP can be obtained after filtering and washing as a raw material for the next step of alkylation; (3) 2,4-DNP and solvent are added to a reactor in proportion and the temperature is raised while maintaining reflux. A certain proportion of an acid binding agent and a catalyst are added to the reactor. An alkylating agent is introduced into the reactor and the temperature is kept high until the reaction is complete. The filtrate is cooled and filtered. The filtrate is added to water after rotary evaporation to precipitate. After filtering and washing with water, the target product 2,4-dinitroanisole can be obtained.

2. The method according to claim 1, characterized in that In step (1), the solvent is any one of N-methylpyrrolidone, acetonitrile, and 1,4-dioxane, and the molar ratio of phenol to the solvent is 1:1-6.

3. The method according to claim 1, characterized in that In step (1), the molar ratio of phenol to concentrated nitric acid is 1:1-6, the reaction temperature is 10-30°C, and the reaction residence time is 1-30 min.

4. The method according to claim 1, characterized in that In step (2), the molar ratio of 4-nitrophenol to concentrated nitric acid is 1:1-6, the reaction temperature is 50-90°C, and the reaction residence time is 5-70 min.

5. The method according to claim 1, characterized in that In step (3), the solvent is any one of dimethyl sulfoxide, N-methylpyrrolidone, and acetone; the acid binding agent is sodium carbonate or potassium carbonate; the catalyst is polyethylene glycol 400 or hexadecyl ammonium bromide; and the alkylating agent is any one of trimethyl orthoformate, dimethyl sulfate, and dimethyl carbonate, preferably dimethyl sulfate.

6. The method according to claim 1, characterized in that In step (3), the molar ratio of 2,4-dinitrophenol, acid binding agent, catalyst and alkylating agent is 1:1~5:1~5:1~10.

7. The method according to claim 1, characterized in that In step (3), the reaction temperature is 30-70°C and the reaction time is 5-120 min.

Images