A method for synthesizing melam

Abstract

The application relates to the technical field of synthesis of carbon nitride flame-retardant materials, and particularly discloses a synthesis method of melam, which comprises the following steps: taking cyanuric chloride as raw material, carrying out ammoniation and coupling to obtain a double-triazine intermediate, and then carrying out sealed ammoniation with ammonia water to obtain melam; and preferably, potassium tert-butylate is used to make the second step reaction obtain BDCAT with a yield of more than 60%; and the third step uses an ammonia water ammoniation process which is relatively safe; the synthesis method is simple, efficient, and avoids the harsh requirements of high-temperature and high-pressure methods on equipment.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of synthesis of carbon nitride flame retardant materials, in particular to a synthesis method of melam. BACKGROUND

[0002] Melam, as a carbon nitride flame retardant, has great potential application value due to higher thermal stability, and most of the synthesis methods thereof need high-temperature and high-pressure conditions (e.g., 2025, 28, e202500240). Eur. J. Inorg. Chem.

[0003] ;

[0004] ;

[0005] ;

[0006] ;

[0007] The method described in the patent US 2475709 for heating melamine to 205 DEG C to generate melam, but the actual reaction cannot stop at the melam stage but continues to condense into melon.

[0008] The method for preparing melam disclosed in the patent CN 1067062 C is to heat a mixture of melamine and p-toluenesulfonic acid to 290 DEG C to generate melam p-toluenesulfonic acid salt, which has high energy consumption and high equipment requirement. SUMMARY

[0009] The application aims to provide a synthesis method for obtaining melam by coupling cyanuric chloride as a raw material and then aminating with ammonia water, so as to solve the problems in the background art.

[0010] To achieve the above object, the application provides the following technical scheme.

[0011] The application provides a synthesis method of melam, and the process route is as follows:

[0012] ;

[0013] ;

[0014] The synthesis method of melam specifically comprises the following steps.

[0015] (1) cyanuric chloride is added into a solvent and stirred, ammonia water is added dropwise, after the amination reaction is completed, water is added, filtration and drying are carried out to obtain DCAT;

[0016] ​(2) stirring DCAT in solvent, adding cyanuric chloride, controlling temperature at 15~20℃, adding base, incubating for 4h, then adding water and stirring for 0.5h, filtering, drying to obtain BDCAT;

[0017] (3) adding BDCAT into a sealed tube, stirring in solvent, adding ammonia, sealing, reacting at room temperature for 0.5~1h, then heating to 100~110℃ for 8~37h, cooling to room temperature, adding hot water and stirring, filtering, drying to obtain melam.

[0018] Further, in step (1), the molar ratio of ammonia to cyanuric chloride is 2.2:1~2.5:1, and the mass ratio of cyanuric chloride to solvent is 1:2.3~2.4.

[0019] Further, in step (1), the solvent is one or more of acetonitrile, acetone, tetrahydrofuran, methanol, ethanol, propanol, and isopropanol.

[0020] Further, in step (1), the temperature of the amination reaction is 0±5℃, and the time of the amination reaction is 4h.

[0021] Further, in step (2), the molar ratio of DCAT, cyanuric chloride, and base is 1:1:1~1:1:1.1, and the mass ratio of DCAT to solvent is 1:3.2~1:2.6.

[0022] Further, in step (2), the solvent is one or more of tetrahydrofuran, dioxane, acetonitrile, and acetone; and the base is one or more of potassium tert-butoxide, sodium tert-butoxide, sodium ethoxide, sodium methoxide, potassium carbonate, sodium carbonate, N,N-diisopropylethylamine, and triethylamine.

[0023] Preferably, in step (2), the solvent is tetrahydrofuran, and the base is potassium tert-butoxide.

[0024] Further, in step (2), the temperature of the incubation reaction is 15~20℃, and the time of the incubation reaction is 4h.

[0025] Further, in step (3), the molar ratio of BDCAT to ammonia is 1:41~42, and the mass ratio of BDCAT to solvent is 1:10.

[0026] Further, in step (3), the solvent is any one or more of dioxane, tetrahydrofuran, acetonitrile, and acetone.

[0027] Preferably, in step (3), the solvent is dioxane.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] The present application provides an organic synthesis method of melam, which uses cyanuric chloride as raw material, enhances the leaving ability of leaving group, and obtains melam through three-step conventional reactions in a simple and efficient manner. The use of preferred potassium tert-butoxide enables the second step reaction to obtain BDCAT at a yield of 60%, and the use of ammonia in the third step is relatively safe, avoiding the harsh requirements of traditional high-temperature and high-pressure methods on equipment. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The synthesis route of the present application;

[0031] Figure 2 The nuclear magnetic resonance hydrogen spectrum of the product melam of the present application. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application. Example 1

[0033] Step (1), synthesis of 2-amino-4,6-dichloro-1,3,5-triazine (DCAT):

[0034] In a reaction bottle, cyanuric chloride 200 g (1.085 mol) and acetonitrile 600 mL were added, stirred, and 25% ammonia water 184.7 g (2.7 mol) was added dropwise at 0±5 ℃ for 3 h. After the dropwise addition was completed, the temperature was maintained and stirring was continued for 1 h. TLC detection showed that the reaction was complete. Then 250 mL of ice water was added, and the filtrate was washed with 300 mL of water. The obtained solid was dried at 60 ℃ for 6 h to obtain white solid DCAT 161.83 g, with a yield of 90.4%; LC-MS m / z : 165.1, 167.0 {[M+H] +}.

[0035] Step (2), synthesis of 4,6-dichloro-N-(4,6-dichloro-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine (BDCAT):

[0036] 15.8 g (0.096 mol) of DCAT and 50 mL of tetrahydrofuran were added to a reaction flask and stirred. 17.66 g (0.096 mol) of cyanuric chloride was then added, followed by the dropwise addition of 11.82 g (0.1 mol) of potassium tert-butoxide dissolved in 100 mL of tetrahydrofuran at 15–20 °C over 50 min. The reaction was maintained at this temperature for 3.5 h. TLC analysis indicated that the reaction was essentially complete. 500 mL of ice water was added and the mixture was stirred for 30 min. The mixture was then filtered under reduced pressure, washed with 50 mL of water, and the resulting solid was dried at 60 °C for 4 h to obtain 18.37 g of white solid BDCAT, with a yield of 61.3%. LC-MS analysis was performed. m / z : 312.0,313.9,315.9 {[M+H] +}

[0037] Step (3), Synthesis of N2-(4,6-diamino-1,3,5-triazin-2-yl)-1,3,5-triazin-2,4,6-triamine (Melam):

[0038] 4 g (12.8 mmol) of BDCAT and 40 mL of dioxane were added to a sealed tube, along with 40 mL (0.53 mol) of 25% ammonia solution. The tube was sealed and stirred at room temperature for 0.5 h. The temperature was then raised to 100 °C and reacted for 37 h. After cooling to room temperature, 100 mL of hot water was added and stirred for 20 min. The mixture was filtered under reduced pressure and washed with 50 mL of hot water (80-90 °C). The resulting solid was dried at 100 °C to obtain 2.6 g of white solid Melam, with a yield of 86.4%. 1 H NMR (400 MHz, DMSO- d 6) δ 9.65 (s, 1H), 6.64 (s, 8H); LC-MS m / z 236.03 {[ M+H] +}, 1H NMR spectrum as Figure 2 As shown. Example 2

[0039] Step (1), Synthesis of 2-amino-4,6-dichloro-1,3,5-triazine (DCAT):

[0040] 400 g (2.17 mol) of cyanuric chloride and 1.2 L of acetonitrile were added to a reaction flask and stirred. 325.2 g (4.77 mol) of 25% ammonia solution was added dropwise at 0±5 °C over 3 h. The temperature was maintained and stirring continued for 1 h. The reaction was monitored by TLC until it was complete. 600 mL of ice water was added dropwise, and the mixture was filtered under reduced pressure. The solution was washed with 300 mL of water, and the resulting solid was dried at 60 °C for 6 h to obtain 325.28 g of white solid DCAT, with a yield of 90.89%.

[0041] Step (2), synthesis of 4,6-dichloro-N-(4,6-dichloro-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine (BDCAT):

[0042] In the reaction bottle, DCAT 134 g (0.8 mol) and dioxane 350 mL were added, stirred, cyanuric chloride 150 g (0.8 mol) was added, and potassium tert-butoxide 98.7 g (0.88 mol) dissolved in 400 mL of tetrahydrofuran was added dropwise at 15~20 ℃, and the dropwise addition was completed in 1.5 h, and the reaction was incubated for 2.5 h; TLC detection showed that the reaction was basically complete, 1.5 L of ice water was added and stirred for 0.5 h, and then filtered under reduced pressure, washed with 500 mL of water, and the obtained solid was dried at 60 ℃ for 4 h to obtain white solid BDCAT 151 g with a yield of 60.56%.

[0043] Step (3), synthesis of N2-(4,6-diamino-1,3,5-triazin-2-yl)-1,3,5-triazine-2,4,6-triamine (Melam)

[0044] In the sealed tube, BDCAT 20 g (64 mmol) and dioxane 200 mL were added, 25% ammonia water 200 mL (2.67 mol) was added, and the reaction was stirred at room temperature for 1 h, then the temperature was increased to 110 ℃ and the reaction was carried out for 8 h, then the temperature was cooled to room temperature, 500 mL of hot water was added and stirred for 30 min, then filtered under reduced pressure, washed with 200 mL of hot water, and the obtained solid was dried at 100 ℃ to obtain white solid Melam 14 g with a yield of 93%. Comparative example

[0045] Step (1), synthesis of 2-amino-4,6-dichloro-1,3,5-triazine (DCAT):

[0046] In the reaction bottle, cyanuric chloride 60 g (0.3 mol) and acetonitrile 0.2 L were added, stirred, and 25% ammonia water 110.4 g (1.6 mol) was added dropwise at 0±5 ℃, and the dropwise addition was completed in 3 h, and the temperature was maintained and stirred for 1 h, and the reaction was detected by TLC, and then 600 mL of ice water was added, filtered under reduced pressure, washed with 100 mL of water, and the obtained solid was dried at 60 ℃ for 6 h to obtain white solid DCAT 20.2 g with a yield of 93.5% (containing a disubstituted by-product).

[0047] Step (2), synthesis of 4,6-dichloro-N-(4,6-dichloro-1,3,5-triazin-2-yl)-1,3,5-triazin-2-amine (BDCAT):

[0048] In a reaction bottle, BDCAT 5.16 g (0.0313 mol) and acetone 75 mL were added, stirred, cyanuric chloride 6.34 g (0.0344 mol) was added, sodium hydroxide 1.25 g (0.0313 mol) dissolved in 10 mL water was added dropwise at 8-15 ℃, dropwise addition was completed in 10 min, the reaction was incubated for 2.5 h; TLC detected that the reaction did not change after half of the reaction, water was added, methyl tert-butyl ether was extracted, sodium sulfate was dried, concentrated, and column chromatography was performed to obtain white solid BDCAT 1 g, with a yield of 10.2%.

[0049] Step (3), synthesis of N2-(4,6-diamino-1,3,5-triazin-2-yl)-1,3,5-triazine-2,4,6-triamine (Melam):

[0050] In a sealed tube, BDCAT 20 g (64 mmol) was added, 25% ammonia water 40 mL (0.535 mol) was added, sealed and raised to 100 ℃ for 9 h, and the reaction was detected to be incomplete.

[0051] It should be noted that the relational terms such as first and second, and the like, are used herein solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0052] It should be noted that the above only illustrates the technical idea of the present application, and cannot limit the protection scope of the present application. For those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which fall within the protection scope of the claims of the present application.

Claims

1. A method of synthesizing melam, characterized by, The method comprises the following steps: The cyanuric chloride is stirred in a solvent, ammonia is added dropwise, and after the amination reaction is completed, water is added, filtered, and dried to obtain DCAT; ； The DCAT is stirred in a solvent, cyanuric chloride is added, the temperature is controlled at 15-20℃, a base is added, and the reaction is carried out under insulation, then water is added and stirred for 0.5h, filtered, and dried to obtain BDCAT; ； The BDCAT is added to a sealed tube, stirred in a solvent, ammonia is added, sealed, and reacted at room temperature for 0.5-1h, then heated to 100-110℃ and reacted for 8-37h, cooled to room temperature, hot water is added and stirred, filtered, and dried to obtain melam; ； In step (2), the solvent is tetrahydrofuran, and the base is potassium tert-butoxide; In step (3), the solvent is dioxane.

2. A process for the synthesis of melam according to claim 1, characterized in that, In step (1), the molar ratio of ammonia to cyanamide is 2.2:1-2.5:1, and the mass ratio of cyanuric chloride to solvent is 1:2.3-2.

4.

3. A process for the synthesis of melam according to claim 2, characterized in that, The solvent in step (1) is one or more of acetonitrile, acetone, tetrahydrofuran, methanol, ethanol, propanol, and isopropanol.

4. A process for the synthesis of melam according to claim 1, characterized by, In step (1), the temperature of the amination reaction is 0±5℃, and the amination reaction time is 4h.

5. A process for the synthesis of melam according to claim 1, characterized by, In step (2), the molar ratio of DCAT, cyanuric chloride, and base is 1:1:1-1:1:1.1, and the mass ratio of DCAT to solvent is 1:3.2-1:2.

6.

6. A process for the synthesis of melam according to claim 1, characterized by, In step (2), the temperature of the insulation reaction is 15-20℃, and the insulation reaction time is 4h.

7. A process for the synthesis of melam according to claim 1, characterized by, In step (3), the molar ratio of BDCAT to ammonia is 1:41-42, and the mass ratio of BDCAT to solvent is 1:10.

Images