A process for the preparation of 4,4',6,6'-tetraaminoazobenzene-1,3,5-triazine

Abstract

The application discloses a preparation method of 4,4',6,6'-tetraminoazo-1,3,5-triazine, belongs to the field of triazine azo compound synthesis, and solves the problems of dispersed preparation steps, harsh reaction conditions and long reaction time of the azo compound. The method comprises the following steps: after trichloro melamine (TCM) is mixed with a sodium hydroxide solution and reacts, a coupling reaction is carried out under stirring at room temperature to obtain 4,4',6,6'-tetrachloroaminoazo-1,3,5-triazine; the 4,4',6,6'-tetrachloroaminoazo-1,3,5-triazine solid is dissolved in an alkaline solution containing a reducing agent to obtain 4,4',6,6'-tetraminoazo-1,3,5-triazine solid. The preparation method provided by the application clearly defines the continuous conversion path of the intermediate, compared with the traditional segmented process, the steps are more compact, the reaction conditions are mild and easy to operate, the total reaction time is significantly shortened, the purity of the target product is effectively improved, and the method has good industrial application potential.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine. 4,4',6,6'-tetraaminoazo-1,3,5-triazine is a class of nitrogen-containing compounds that simultaneously integrate a 1,3,5-triazine heterocycle, an azo conjugated structure, and multiple amino functional groups. These structural characteristics give it potential application value in functional dyes, pharmaceutical intermediates, and biomolecular recognition probes. The preparation method provided by this invention can synthesize this compound efficiently and with high purity. Background Technology

[0002] The conjugated system of the six-membered triazine ring endows it with good chemical and thermal stability. Meanwhile, the carbon atoms on the ring (such as at positions 4 and 6) exhibit high reactivity, allowing for the convenient introduction of azo groups (-N=N-). This structure endows it with potential application value in functional dyes, optoelectronic functional materials (such as organic photoconductors), pharmaceutical intermediates (nitrogen-containing heterocyclic drug precursors), and biomolecular recognition probes. Currently, the main reported methods for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine are as follows: Route: Hydrazine monohydrate (34.45 mmol) is slowly added to a solution of trichlorotriazine (68.9 mmol) and potassium carbonate (68.9 mmol) while stirring at 50 °C. A condenser was connected to the reaction system, and the reaction was carried out overnight at 50 °C in an oil bath to obtain N,N'-bis(4,6-dichloro-[1,3,5]triazin-2-yl)hydrazine. A solution was then prepared by dissolving 35 mL of 31.5 g / L ammonia and 11.6 g of sodium bicarbonate in 100 mL of water and stirring at room temperature. Simultaneously, 7.2 g of N,N'-bis(4,6-dichloro-[1,3,5]triazin-2-yl)hydrazine dissolved in 75 mL of acetone was added. The solution was initially bright yellow, becoming powdery and thickening with increasing temperature. The reactants were heated to 65 °C and allowed to stand overnight to obtain a white suspension. The suspension was filtered, and the precipitate was washed with plenty of water to remove alkali and chloride salts, followed by washing with acetone and drying under vacuum to obtain N,N'-bis-(4,6-diamino-(1,3,5)triazine-2-yl)-hydrazine. 11 g of NBS (64 mM) was dissolved in 150 mL of acetonitrile, and then 4.02 g of N,N'-bis-(4,6-diamino-(1,3,5)triazine-2-yl)-hydrazine (16 mM) was added in portions. The initially white suspension slowly transformed into an orange product under reflux for 4 h. The acetonitrile supernatant was decanted, 500 mL of water was added, the suspension was sonicated for 10 min, and then allowed to precipitate. The resulting product was dried in an oven to obtain 4,4',6,6'-tetraaminoazo-1,3,5-triazine (Journal of Energetic Materials 27.2 (2009): 63-93). This route also suffers from numerous steps, long reaction times, and cumbersome operations, and the small amount of reagents used in each step makes it difficult to achieve industrial-scale production. Therefore, developing a method that is mild in reaction conditions, simple in operation, environmentally friendly, and efficient in preparing high-purity 4,4',6,6'-tetraaminoazo-1,3,5-triazine has significant practical application value. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of existing methods for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine, such as cumbersome reaction steps, harsh conditions, high reagent toxicity, and low yield. This invention provides a method that is mild in reaction conditions, simple in operation, environmentally friendly, and can efficiently prepare high-purity 4,4',6,6'-tetraaminoazo-1,3,5-triazine. To achieve the above-mentioned objectives, the present invention provides the following technical solutions: (1) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: TCM raw material is mixed with sodium hydroxide under stirring and reacted to obtain 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine product; (2) Preparation of 4,4', 6,6'-tetraaminoazo-1,3,5-triazine: The product of step (1) is dissolved in sodium carbonate solution, and sodium thiosulfate solid is added. After the crystals precipitate, they are separated and dried to obtain pure 4,4', 6,6'-tetraaminoazo-1,3,5-triazine. Further, in step (1), the alkaline solvent is an aqueous solution of sodium hydroxide, an aqueous solution of potassium hydroxide, an aqueous solution of lithium hydroxide, or a mixture thereof, with a concentration of 1 to 3 mol∙L. -1 To ensure that the TCM raw material and sodium hydroxide are fully dissolved and to maintain the alkaline environment of the reaction system. Further, in step (1), the molar ratio of TCM raw material to alkali is 1:1 to 1:5. Further, in step (1), the stirring speed is 100 to 500 r / min, and the two solutions are mixed evenly by continuous stirring. Further, in step (1), the reaction temperature is controlled at 10℃ to 40℃, preferably 20℃ to 30℃; the reaction time is 5 to 30 minutes, preferably 8 to 20 minutes. Further, in step (2), the amount of water used is preferably enough to almost dissolve the product obtained in step (1). Further, in step (2), the alkaline solvent is sodium carbonate, sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, aqueous solution or various mixtures, and its concentration is 0.5 to 3 mol∙L. -1 Further, in step (2), the reducing solvent is one or a mixture of sodium thiosulfate and sodium sulfite solutions. Its concentration is 1–5 mol·L⁻¹. -1Further, in step (2), the reaction temperature is controlled at 20℃~40℃, preferably 20℃~30℃; the reaction time is 5~40 minutes, preferably 10~30 minutes. Further, in step (2), the stirring speed is 100~400r / min, and the two solutions are mixed evenly by continuous stirring. Compared with the prior art, the present invention has the following beneficial effects: the prior art requires multiple steps of reaction and consumes time and materials to complete the synthesis, with a total time of several hours to tens of hours; while the present invention can be completed in only two steps, with the reaction stage requiring only 1~30 minutes. The overall process is short and simple to operate, greatly improving the preparation efficiency. The prior art requires harsh conditions such as high temperature reflux, oxygen supply or long-term standing (24 h), which consumes a lot of energy and is complicated to operate; the reaction temperature of the present invention is only 20℃~30℃, without the need for high temperature and high pressure or special gas atmosphere, and the conditions are mild and easy to control, reducing the requirements for equipment and the operational risks. Existing technologies rely on reagents with safety risks, such as hydrazine hydrate (toxic) and ammonia, which can easily cause environmental pollution and product residues. This invention uses sodium hydroxide as the reaction reagent, which has low toxicity and simple post-processing. The alkaline solvent can be recycled, reducing the discharge of waste gas, wastewater, and solid waste, and conforming to the principles of green chemistry. (See attached figures.) Figure 1 The 1H NMR spectra of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine (A) and 4,4', 6,6'-tetraaminoazo-1,3,5-triazine (B) prepared in Example 1 (solvent: (CD3)2SO, 400MHz). Figure 2 The infrared spectra (KBr pellets) of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine (A) and 4,4', 6,6'-tetraaminoazo-1,3,5-triazine (B) prepared in Example 1 are shown. Figure 3 Raman spectra (excitation wavelength 785 nm) of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine (A) and 4,4', 6,6'-tetraaminoazo-1,3,5-triazine (B) prepared in Example 1. Figure 4 High-resolution mass spectra of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine (A) and 4,4', 6,6'-tetraaminoazo-1,3,5-triazine (B) prepared in Example 1. Detailed Embodiments: The present invention will be described in detail below through specific examples, but the scope of protection of the present invention is not limited to these examples. Example 1: (1) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: 1.80 g (1 mol) of TCM was added to 20 mL of a 1 mol·L⁻¹ solution. -1(1) Sodium hydroxide aqueous solution was stirred at 20°C and 200 r / min until completely dissolved. After mixing, the reaction was continued for 10 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried. (2) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: 0.1 g of the above 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was added to 20 mL of 0.5 mol sodium carbonate and stirred to dissolve the solid. Then 1 mol of sodium thiosulfate solid was added and stirred at 25°C and 300 r / min until completely dissolved. The reaction was continued for 20 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried. The 1H NMR spectra of 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine and 4,4',6,6'-tetraaminoazo-1,3,5-triazine obtained in this example are as follows: Figure 1 As shown, the spectrum is described as follows: ¹H NMR (400 MHz, DMSO-d6) δ 10.05 (s, 3H), 8.94 (s, 1H); ¹H NMR (400 MHz, DMSO-d6) δ 7.18 (s, 1H), 7.11 (s, 1H). The infrared spectra of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine and 4,4', 6,6'-tetraaminoazo-1,3,5-triazine obtained in this example are as follows. Figure 2 As shown, the spectrum is described as follows: 4,4',6,6'-tetraaminoazo-1,3,5-triazine appears at 3460 cm⁻¹. -1 3136 cm -1 The presence of -NH2 was confirmed by the appearance of 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine at 709 cm⁻¹. -1 Proof of N-Cl- formation. 1300cm -1 ~1650 cm -1 The absorption peak at 586 cm⁻¹ is attributed to both the stretching vibrations of the -CH- and -NH- bonds on the ring. -1 590 cm -1 783 cm -1 and 817 cm -1 The absorption peaks for bending vibrations of the ring skeleton further confirmed the presence of the triazine ring. The Raman spectra of 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine and 4,4',6,6'-tetraaminoazo-1,3,5-triazine obtained in this example are as follows: Figure 3 As shown, the description of this spectrum is as follows: 1034 cm -1 1600 cm-1 1604cm -1 The characteristic Raman peaks of the azo group (-N=N-) confirm the presence of an azo structure in the molecule; 1070 cm⁻¹ -1 1079 cm -1 1285 cm -1 1318 cm -1 1476 cm -1 1462 cm -1 Corresponding to the NH or C=N stretching vibration of the triazine ring; 963 cm -1 950cm -1 Corresponding to the skeletal bending vibration of the triazine ring, the molecule retains the triazine ring. The high-resolution mass spectra of 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine and 4,4',6,6'-tetraaminoazo-1,3,5-triazine obtained in this example are shown below. Figure 4 As shown, the spectrum is described as follows: 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine has a theoretical molecular weight of 383.944, an actual proton peak of 834.950, and mass spectra of sodium addition peaks of 406.932 and 428.914; 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine has a theoretical molecular weight of 248.099, an actual proton peak of 249.105, and mass spectra of sodium addition peak of 271.088. Example 2: (1) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: 2.00 g (1 mol) of TCM was added to 20 mL of a 2 mol∙L⁻¹ solution. -1 (1) Sodium hydroxide aqueous solution was stirred at 25°C and 300 r / min until completely dissolved. After mixing, the reaction was continued for 20 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried. (2) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: 0.55 g of the above 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was added to 20 mL of 1 mol / L sodium carbonate. The solid was stirred to dissolve. Then 2 mol of sodium thiosulfate solid was added. The mixture was stirred at 25°C and 400 r / min until completely dissolved. The reaction was continued for 25 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried. Example 3: (1) Preparation of 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine: 2.50 g (1 mol) of TCM was added to 20 mL of a solution with a concentration of 3 mol·L⁻¹. -1(1) Sodium hydroxide aqueous solution was stirred at 30°C and 500 r / min until completely dissolved. After mixing, the reaction was continued for 30 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried. (2) Preparation of 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine: 0.55 g of the above 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was added to 20 mL of 1 mol / L sodium carbonate. The solid was stirred to dissolve. Then 3 mol of sodium thiosulfate solid was added. The mixture was stirred at 25°C and 500 r / min until completely dissolved. The reaction was continued for 30 minutes, and 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine precipitate was formed. The precipitate was filtered and dried.

Claims

1. A method for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine, characterized in that, Includes the following steps: (1) TCM and sodium hydroxide solution were coupled together at 10-50°C for 1-30 min to obtain 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine; (2) The 4,4', 6,6'-tetrachloroamineazo-1,3,5-triazine solid was dissolved in an alkaline solution containing a reducing agent and stirred at 10-50°C for 1-30 min to obtain pure 4,4', 6,6'-tetraaminoazo-1,3,5-triazine solid.

2. The method for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine according to claim 1, characterized in that, The alkaline solvent is one or a mixture of sodium hydroxide, potassium hydroxide, and sodium carbonate aqueous solutions, and the concentration of the alkaline solvent is 1–3 mol·L⁻¹. -1 .

3. The method for preparing 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine according to claim 1, characterized in that, In step (1), the reaction temperature is 10℃~40℃.

4. The method for preparing 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine according to claim 1, characterized in that, In step (1), the stirring speed is 100-500 r / min.

5. The method for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine according to claim 1, characterized in that, In step (2), the reducing solvent is one or a mixture of sodium thiosulfate and sodium sulfite solution.

6. The method for preparing 4,4',6,6'-tetraamineazo-1,3,5-triazine according to claim 1, characterized in that, In step (2), the stirring speed is 100-400 r / min.

7. The method for preparing 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine according to claim 1, characterized in that, In step (1), the 4,4',6,6'-tetrachloroamineazo-1,3,5-triazine structure is as follows:

8. The method for preparing 4,4',6,6'-tetraaminoazo-1,3,5-triazine according to claim 1, characterized in that, In step (2), the 4,4',6,6'-tetraamineazo-1,3,5-triazine structure is as follows:

9. 4,4',6,6'-tetraaminoazo-1,3,5-triazine obtained by the preparation method according to any one of claims 1 to 8.

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