A safe and environmentally friendly method for preparing dinitroaromatic hydrocarbons

Abstract

This invention relates to the field of chemical intermediate preparation, specifically to a safe and environmentally friendly method for preparing dinitroaromatic hydrocarbons. The invention employs a liquid acid / nitrate system nitration method. Starting with aromatic hydrocarbons, this method uses nitrate as the nitrating agent and polyphosphoric acid (PPA) as the reaction solvent, undergoing a nitration reaction at room temperature to prepare dinitroaromatic hydrocarbons. The dinitration synthesis method provided by this invention uses nitrate / polyphosphoric acid as the nitrating agent, replacing the traditional mixed acid system for aromatic hydrocarbon dinitration. This solves the problems of environmental pollution and equipment corrosion caused by the traditional mixed acid system. This invention has advantages such as simple synthesis method and post-reaction processing, mild and safe reaction conditions, and high yield of dinitration products. From a green synthesis perspective, this aligns with the development concept of green chemistry and provides a new approach and method for large-scale industrial preparation of dinitroaromatic hydrocarbons.

Description

Technical Field

[0001] This invention relates to a safe and environmentally friendly method for preparing dinitro aromatic hydrocarbons, specifically a method for dinitrifying aromatic hydrocarbon compounds under conditions of polyphosphoric acid and potassium nitrate, belonging to the field of fine chemicals. Background Technology

[0002] The nitration of aromatic compounds is an important electrophilic substitution reaction in chemical production. The nitration products of aromatic compounds are also important fine chemical intermediates, widely used in dyes, pharmaceuticals, pesticides, and explosives. For example, 2,4-dinitrofluorobenzene is a crucial raw material for organofluorine fine chemicals, a primary raw material for manufacturing quinolone drugs such as ciprofloxacin, pefloxacin, and difluorofloxacin, and is also used in fluorinated pesticides, insecticides, and herbicides. 2,4-dinitrochlorobenzene is a commonly used molecular polymerization inhibitor in industry and can also be used to produce high-value-added downstream products such as sulfur black dyes, o-benzoylsulfonylimide, 2,4-dinitroaniline, and 2,4,6-trinitrophenol. 2,4-dinitroanisole is mainly used as a dye intermediate and an insecticide. 2,4-dinitrotoluene and 2,4,6-trinitrotoluene are widely used in the manufacture of explosives. However, due to the special properties of dinitrated aromatic hydrocarbons, the country strictly controls the production process of dinitrated aromatic hydrocarbons. At present, the domestic demand for dinitration products is large, which often leads to a situation of supply falling short of demand.

[0003] Most processes for preparing dinitroaromatic hydrocarbons employ concentrated nitric acid systems or mixed acid systems. Regarding concentrated nitric acid systems, Russian patent RU2572516C1 reports the use of concentrated nitric acid to dinitrate phenol at 80°C to produce 2,4-dinitrophenol, with excellent yields. For mixed acid systems, the most common system is the concentrated nitric acid-concentrated sulfuric acid system. Chinese patent CN103936559A reported the use of concentrated nitric acid-concentrated sulfuric acid system to dinitrate benzene at 120℃ to produce 1,3-dinitrobenzene with excellent yield. Foreign patent WO2020175671A1 reported the use of concentrated nitric acid-concentrated sulfuric acid system to dinitrate 4-methyltrifluorotoluene at 50℃ to produce 4-methyl-3,5-dinitrobenzene. In addition, Wu Yanxuan et al. innovatively used a mixed acid system of trifluoromethanesulfonic acid-concentrated nitric acid to dinitrate benzene at room temperature to produce 1,3-dinitrobenzene with good yield (Journal of Organic Chemistry, 2023, 88(15), 11322-11327). However, the two traditional dinitration systems mentioned above have high requirements for the reaction environment, high purification costs for the reaction products, and are difficult to recycle and reuse. During production, a large amount of volatile nitric acid or nitrogen dioxide gas is released, which not only easily corrodes equipment but also causes serious environmental pollution and threatens the health of production workers. Based on the principles of environmental protection and safe production, to fundamentally reduce or eliminate the pollution of the chemical industry, research on nitration reactions should shift to green nitration technology research. To this end, this invention employs a polyphosphoric acid-potassium nitrate liquid acid / nitrate nitration system with low environmental pollution—using polyphosphoric acid with lower acidity than sulfuric acid and nitric acid, no oxidizing ability, and greater stability and safety to provide acidic conditions for the nitration reaction; high reaction efficiency—excellent yield; simple post-treatment—product extraction after hydrolysis by adding water; and excellent safe production environment—nitration can be carried out at room temperature. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing nitration technologies and provide a safe and environmentally friendly method for preparing dinitro aromatic hydrocarbons.

[0005] The present invention adopts the following technical solution:

[0006] A safe and environmentally friendly method for preparing dinitroaromatic hydrocarbons involves a reaction system in polyphosphoric acid, using aromatic hydrocarbons as raw materials and nitrates as nitrating agents. The system is stirred at room temperature for 1-15 hours until the reaction is complete. Finally, water is added to quench the reaction. The product is then extracted with an organic solvent, washed with water, dried, filtered, concentrated, and purified to obtain the dinitroaromatic hydrocarbon compound.

[0007] Furthermore, the nitrate in the nitrifying agent is any one of sodium nitrate, potassium nitrate, zinc nitrate, or ferric nitrate, more preferably potassium nitrate.

[0008] Furthermore, polyphosphoric acid (PPA) is used as the nitration solvent.

[0009] Furthermore, the amount of the nitrifying agent added is 2.2-2.4 equivalents, more preferably 2.3 equivalents.

[0010] Furthermore, the aromatic hydrocarbon is a compound containing an electron-donating group or containing both electron-donating and electron-withdrawing groups.

[0011] Furthermore, the aromatic hydrocarbons include, but are not limited to, aromatic hydrocarbon compounds such as benzene, chlorobenzene, fluorobenzene, anisole, bromobenzene, 4-methoxybenzaldehyde, 2-methyltrifluorotoluene, 4-methoxyacetophenone, 4-methyltrifluorotoluene, and 4-hydroxyacetophenone.

[0012] The organic solvent is dichloromethane or dichloroethane, more preferably dichloroethane.

[0013] As can be seen from the above description of the present invention, compared with existing nitration technology, the beneficial effects of the present invention are:

[0014] First, the innovation of this invention lies primarily in abandoning the current traditional mixed acid dinitration system and choosing a liquid acid / nitrate system with a higher safety factor and more thorough reaction. The mechanism of nitrate nitration is the capture of NO2 by aromatic free radical cations. + The process involves the formation of Wheland intermediates. This process has advantages such as low waste acid emissions, low corrosivity, and easy product separation. The selected nitrating agent—potassium nitrate—is relatively inexpensive, harmless to the human body, and easy to store; the selected protic acid solvent—polyphosphoric acid—can dissolve both low-molecular-weight and high-molecular-weight compounds; and polyphosphoric acid is weaker than nitric acid and sulfuric acid, but stronger than acetic acid, and has no oxidizing ability, thus having low toxicity to the human body.

[0015] Secondly, traditional concentrated nitric acid systems or mixed acid systems of concentrated nitric acid and concentrated sulfuric acid are criticized by most processes due to the severe acidic water pollution caused by the strong acids used, the violent reaction process, and the strong corrosion to equipment. This application offers advantages such as less environmental pollution—using polyphosphoric acid, which is less acidic than sulfuric acid and nitric acid, has no oxidizing ability, and is more stable and safer to provide acidic conditions for the nitration reaction; high reaction efficiency—excellent yield; simple post-treatment—product extraction after hydrolysis by adding water dropwise; and excellent production environment—nitration can be carried out at room temperature. From the perspective of green synthesis, this aligns with the concepts of green chemistry and safe production, providing a new approach and method for the large-scale industrial preparation of dinitroaromatic hydrocarbons. Attached Figure Description

[0016] Figure 1 This is a synthetic route diagram for 1,3-dinitrobenzene;

[0017] Figure 2 This is the GC spectrum of benzene;

[0018] Figure 3 The GC spectrum of the benzene nitration reaction solution is shown.

[0019] Figure 4 The GC spectrum of a 1,3-dinitrobenzene standard sample;

[0020] Figure 5 This is a route diagram for the synthesis of 2,4-dinitrochlorobenzene;

[0021] Figure 6 The GC spectrum of chlorobenzene is shown below.

[0022] Figure 7 The GC spectrum of the chlorobenzene nitration reaction solution is shown.

[0023] Figure 8 The GC spectrum of the 2,4-dinitrochlorobenzene standard sample;

[0024] Figure 9 This is a route diagram for the synthesis of 2,4-dinitrofluorobenzene;

[0025] Figure 10 The GC spectrum of fluorobenzene;

[0026] Figure 11 The GC spectrum of the fluorobenzene nitration reaction solution is shown.

[0027] Figure 12 The GC spectrum of the 2,4-dinitrofluorobenzene standard sample;

[0028] Figure 13 This is a synthetic route diagram for 2,4-dinitroanisole;

[0029] Figure 14 The GC spectrum of anisole;

[0030] Figure 15 The GC spectrum of the anisole nitration reaction solution;

[0031] Figure 16 The GC spectrum of a 2,4-dinitroanisole standard sample;

[0032] Figure 17 This is a synthetic route diagram for 2,4-dinitrobromobenzene;

[0033] Figure 18 The GC spectrum of bromobenzene is shown below.

[0034] Figure 19 The GC spectrum of the bromobenzene nitration reaction solution is shown.

[0035] Figure 20 The GC spectrum of the 2,4-dinitrobromobenzene standard sample;

[0036] Figure 21 The synthetic route for 4-methoxy-3,5-dinitrobenzaldehyde;

[0037] Figure 22 The GC spectrum of 4-methoxybenzaldehyde;

[0038] Figure 23 The GC spectrum of the nitration reaction solution of 4-methoxybenzaldehyde;

[0039] Figure 24 The GC spectrum of the 4-methoxy-3,5-dinitrobenzaldehyde standard sample is shown.

[0040] Figure 25 Synthetic route diagram for 2-methyl-3,5-dinitrotrifluorotoluene;

[0041] Figure 26 The GC spectrum of 2-methyltrifluorotoluene;

[0042] Figure 27 The GC spectrum of the nitration reaction solution of 2-methyltrifluorotoluene is shown.

[0043] Figure 28 The GC spectrum of the 2-methyl-3,5-dinitrotrifluorotoluene standard sample;

[0044] Figure 29 This is a synthetic route diagram for 4-methoxy-3,5-dinitroacetophenone;

[0045] Figure 30 The GC spectrum of 4-methoxyacetophenone;

[0046] Figure 31 The GC spectrum of the nitration reaction solution of 4-methoxyacetophenone;

[0047] Figure 32 The GC spectrum of the 4-methoxy-3,5-dinitroacetophenone standard sample is shown below.

[0048] Figure 33 Synthetic route diagram for 4-methyl-3,5-dinitrotrifluorotoluene;

[0049] Figure 34 The GC spectrum of 4-methyltrifluorotoluene;

[0050] Figure 35 The GC spectrum of the nitration reaction solution of 4-methyltrifluorotoluene is shown.

[0051] Figure 36 The GC spectrum of the 4-methyl-3,5-dinitrotrifluorotoluene standard sample;

[0052] Figure 37This is a synthetic route diagram for 4-hydroxy-3,5-dinitroacetophenone.

[0053] Figure 38 The GC spectrum of 4-hydroxyacetophenone;

[0054] Figure 39 The GC spectrum of the nitration reaction solution of 4-hydroxyacetophenone;

[0055] Figure 40 The GC spectrum of the 4-hydroxy-3,5-dinitroacetophenone standard sample is shown below.

[0056] Figure 41 The GC spectrum of the reaction solution for the dinitration of 2-methyltrifluorotoluene (potassium nitrate-acetic acid nitration system);

[0057] Figure 42 The GC spectrum of the reaction solution for the dinitration of 2-methyltrifluorotoluene (potassium nitrate-concentrated sulfuric acid nitration system);

[0058] Figure 43 The GC spectrum of the reaction solution for the dinitration of 2-methyltrifluorotoluene (concentrated nitric acid-concentrated sulfuric acid nitration system); Detailed Implementation

[0059] The present invention will be further described below through specific embodiments.

[0060] A safe and environmentally friendly method for preparing dinitro aromatic hydrocarbons involves a reaction system composed of aromatic hydrocarbons as raw materials and nitrates as nitrating agents in polyphosphoric acid. The system is stirred at room temperature for 1-15 hours until the reaction is complete. Finally, an appropriate amount of water is added to quench the reaction. The product is then extracted with an organic solvent, washed with water, dried, filtered, concentrated, and purified to obtain the dinitro aromatic hydrocarbon compound.

[0061] The nitrate is sodium nitrate, potassium nitrate, zinc nitrate or ferric nitrate, more preferably potassium nitrate; specifically, the amount of nitrifying agent added is 2.2-2.4 equivalents, more preferably 2.3 equivalents.

[0062] Aromatic hydrocarbons are compounds containing electron-donating groups or both electron-donating and electron-withdrawing groups; specifically, aromatic hydrocarbons include benzene, chlorobenzene, fluorobenzene, anisole, bromobenzene, 4-methoxybenzaldehyde, 2-methyltrifluorotoluene, 4-methoxyacetophenone, 4-methyltrifluorotoluene, and 4-hydroxyacetophenone.

[0063] Example 1

[0064] The preparation method of 1,3-dinitrobenzene, and its synthetic route refer to Figure 1

[0065] The specific method is as follows:

[0066] 500 mg of benzene was placed in a 100 mL three-necked flask, 1.491 g of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 1 hour. After the reaction was complete, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 1,3-dinitrobenzene, with a yield of 98.6%. The GC temperature program consisted of an initial temperature of 60 °C held for 2 min, followed by a temperature increment of 30 °C / min until the end of the heating period.

[0067] Example 2

[0068] The preparation method of 2,4-dinitrochlorobenzene, and its synthetic route refer to Figure 5

[0069] The specific method is as follows:

[0070] 500 mg of chlorobenzene was placed in a 100 mL three-necked flask, 1.033 g of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 2 hours. After the reaction was complete, 80 mL of water was added dropwise to quench the reaction. The reaction solution was then extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2,4-dinitrochlorobenzene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0071] Example 3

[0072] The preparation method of 2,4-dinitrofluorobenzene, and its synthetic route refer to Figure 9

[0073] The specific method is as follows:

[0074] 500 mg of fluorobenzene was placed in a 100 mL three-necked flask, 1.210 g of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 3 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was then extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2,4-dinitrofluorobenzene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 50 °C held for 2 min, followed by a temperature increment of 30 °C / min until the end of the heating period.

[0075] Example 4

[0076] The preparation method of 2,4-dinitroanisole, and its synthetic route refer to Figure 13

[0077] The specific method is as follows:

[0078] 500 mg of anisole was placed in a 100 mL three-necked flask, 1.075 g of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 2 hours. After the reaction was complete, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2,4-dinitroanisole, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 120 °C held for 2 min, followed by a temperature increment of 20 °C / min until the end of the heating period.

[0079] Example 5

[0080] The preparation method of 2,4-dinitrobromobenzene, its synthetic route is as follows: Figure 17

[0081] The specific method is as follows:

[0082] 500 mg of bromobenzene was placed in a 100 mL three-necked flask, 740 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 15 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2,4-dinitrobromobenzene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 120 °C held for 2 min, followed by a temperature increment of 20 °C / min until the end of the heating period.

[0083] Example 6

[0084] The preparation method of 4-methoxy-3,5-dinitrobenzaldehyde, and its synthetic route refer to Figure 21

[0085] The specific method is as follows:

[0086] 500 mg of 4-methoxybenzaldehyde was placed in a 100 mL three-necked flask, 854 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 8 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 4-methoxy-3,5-dinitrobenzaldehyde, with a yield of 74.3%. The GC temperature program consisted of an initial temperature of 180 °C held for 2 min, followed by a temperature increment of 15 °C / min until the end of the heating period.

[0087] Example 7

[0088] The preparation method of 2-methyl-3,5-dinitrotrifluorotoluene, the synthetic route is as follows: Figure 25

[0089] The specific method is as follows:

[0090] 500 mg of 2-methyltrifluorotoluene was placed in a 100 mL three-necked flask, 726 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 5 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2-methyl-3,5-dinitrotrifluorotoluene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0091] Example 8

[0092] The preparation method of 4-methoxy-3,5-dinitroacetophenone, and its synthetic route refer to Figure 29

[0093] The specific method is as follows:

[0094] 500 mg of 4-methoxyacetophenone was placed in a 100 mL three-necked flask, 774 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 5 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 4-methoxy-3,5-dinitroacetophenone, with a yield of 66.1%. The GC temperature program consisted of an initial temperature of 180 °C held for 2 min, followed by a temperature increment of 15 °C / min until the end of the heating period.

[0095] Example 9

[0096] The preparation method of 4-methyl-3,5-dinitrotrifluorotoluene, and its synthetic route refer to Figure 33

[0097] The specific method is as follows:

[0098] 500 mg of 4-methyltrifluorotoluene was placed in a 100 mL three-necked flask, 726 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 12 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 4-methyl-3,5-dinitrotrifluorotoluene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0099] Example 10

[0100] The preparation method of 4-hydroxy-3,5-dinitroacetophenone, and its synthetic route are as follows: Figure 37

[0101] The specific method is as follows:

[0102] 500 mg of 4-hydroxyacetophenone was placed in a 100 mL three-necked flask, 854 mg of potassium nitrate was added, followed by 10 mL of PPA. The mixture was stirred at room temperature for 8 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The mixture was then extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 4-hydroxy-3,5-dinitroacetophenone, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 180 °C held for 2 min, followed by a temperature increment of 30 °C / min until the end of the heating period.

[0103] Comparative Example

[0104] To examine the superiority of the technology of this invention, experiments were conducted successively using a potassium nitrate-acetic acid nitration system, a potassium nitrate-concentrated sulfuric acid nitration system, and a concentrated nitric acid-concentrated sulfuric acid nitration system to perform the dinitration reaction of 2-methyltrifluorotoluene in Example 7. The reaction steps and results are shown below:

[0105] Comparative Example 1

[0106] 500 mg of 2-methyltrifluorotoluene was placed in a 100 mL three-necked flask, 726 mg of potassium nitrate was added, followed by 10 mL of acetic acid. The mixture was stirred at room temperature for 5 hours. After the reaction was complete, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated. GC analysis showed that the reaction had not proceeded. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0107] Comparative Example 2

[0108] 500 mg of 2-methyltrifluorotoluene was placed in a 100 mL three-necked flask, 726 mg of potassium nitrate was added, followed by 10 mL of concentrated sulfuric acid. The mixture was stirred at room temperature for 5 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2-methyl-3,5-dinitrotrifluorotoluene, with a yield of 83.3%. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0109] Comparative Example 3

[0110] 500 mg of 2-methyltrifluorotoluene was placed in a 100 mL three-necked flask, 5.327 g of concentrated nitric acid (68%) was added, followed by 10 mL of concentrated sulfuric acid. The reaction was stirred at room temperature for 5 hours. After the reaction was completed, 80 mL of water was added dropwise to quench the reaction. The reaction solution was extracted with dichloroethane, washed with water, dried over anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated to obtain the product. GC analysis confirmed that the product was 2-methyl-3,5-dinitrotrifluorotoluene, with a yield of 100.0%. The GC temperature program consisted of an initial temperature of 100 °C held for 2 min, followed by a temperature increment of 25 °C / min until the end of the heating period.

[0111] in, Figure 41 , Figure 42 and Figure 43 The GC spectra of the dinitration reaction of 2-methyltrifluorotoluene in the potassium nitrate-acetic acid nitration system, the potassium nitrate-concentrated sulfuric acid nitration system, and the nitric acid-concentrated sulfuric acid nitration system are shown respectively, with yields of 0%, 83.3%, and 100%, respectively. This indicates that the potassium nitrate-acetic acid nitration system and the potassium nitrate-concentrated sulfuric acid nitration system are far inferior to the potassium nitrate-polyphosphoric acid system of this invention. Although the results of the concentrated nitric acid-concentrated sulfuric acid nitration system are consistent with those of the potassium nitrate-polyphosphoric acid system of this invention, this is based on the presence of excess nitric acid. Therefore, the concentrated nitric acid-concentrated sulfuric acid nitration system is far inferior to the results shown by using 2.3 equivalents of potassium nitrate as the nitrating agent in this invention. This sufficiently demonstrates the advantages of the dinitroaromatic hydrocarbon preparation method of this invention.

Claims

1. A safe and environmentally friendly method for preparing dinitroaromatic hydrocarbons, characterized in that: In a nitrification solvent, a reaction system consisting of aromatic hydrocarbons as raw materials and nitrates as nitrating agents is stirred at room temperature for 1-15 hours until the reaction is complete. Finally, water is added to quench the reaction. The product is extracted with an organic solvent, washed with water, dried, filtered, concentrated, and purified to obtain a dinitroaromatic hydrocarbon compound. The nitrate used is any one of sodium nitrate, potassium nitrate, zinc nitrate, or ferric nitrate. The amount of nitrate added is 2.2-2.4 equivalents. The nitrification solvent is polyphosphate (PPA). The aromatic hydrocarbon includes any one of benzene, chlorobenzene, fluorobenzene, anisole, bromobenzene, 4-methoxybenzaldehyde, 2-methyltrifluorotoluene, 4-methoxyacetophenone, 4-methyltrifluorotoluene, and 4-hydroxyacetophenone. The organic solvent is dichloromethane or dichloroethane.

2. The method for preparing a safe and environmentally friendly dinitroaromatic hydrocarbon according to claim 1, characterized in that: The nitrate used is potassium nitrate.

3. The method for preparing a safe and environmentally friendly dinitroaromatic hydrocarbon according to claim 1, characterized in that: The amount of nitrate added was 2.3 equivalents.

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