A process for the preparation of a triazine arylamine dimer

Abstract

This invention provides a method for preparing triazine aromatic amine dimers. The method involves mixing a triazine compound monomer and an inorganic salt, followed by a high-temperature solid-phase reaction to obtain a crude product. The crude product is then washed to remove the inorganic salt, yielding the triazine aromatic amine dimer. The inorganic salt is selected from one or more of lithium bromide, lithium chloride, lithium fluoride, zinc chloride, and zinc sulfate. This method uses the inorganic salt as a "dynamic active interface" to precisely guide the reaction pathway during the high-temperature solid-phase reaction, achieving highly selective synthesis of triazine aromatic amine dimers. It offers advantages such as high product selectivity, a green process, simple operation, and recyclable inorganic salts.

Description

[0001] This invention relates to the field of chemical synthesis technology, specifically to a method for preparing triazine aromatic amine dimers. Background Technology

[0002] Triazine aromatic amine dimers are a class of compounds formed by the linkage of triazine monomers through a secondary amine bridging structure, as shown in Formula I. Formula I This class of compounds encompasses a variety of structures and exhibits diverse performance characteristics. They are a class of high-performance nitrogen-based flame retardants with significant application value in flame-retardant polymer materials. The differences in the R groups are used to regulate the compatibility between the flame retardant and the polymer substrate. In particular, 2,4,6-triamino-1,3,5-triazine is a potential alternative to currently commercially available melamine flame retardants. Furthermore, 2,4-diamino-6-phenyl-1,3,5-triazine and 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine also exhibit excellent organic light-emitting properties, making them a class of promising organic light-emitting materials.

[0003] Traditional methods for preparing triazine aromatic amine dimers mainly involve wet chemical organic synthesis, such as the deHCl coupling method. This method involves chlortriazine derivatives as raw materials, which pose significant health risks due to their biotoxicity (as raw materials for pesticide manufacturing). It also generates organic waste liquid. Summary of the Invention

[0004] To address the problems existing in the background technology, the present invention provides a method for preparing triazine aromatic amine dimers. This method innovatively introduces a specific inorganic salt as a "dynamic active interface" to precisely guide the reaction path in a high-temperature solid-phase reaction, thereby achieving highly selective and high-yield synthesis of triazine aromatic amine dimers. The entire process does not require organic solvents, is green and environmentally friendly, and the inorganic salts can be recycled.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: A method for preparing a triazine aromatic amine dimer, comprising: mixing a triazine compound monomer and an inorganic salt and then subjecting the mixture to a high-temperature solid-phase reaction to obtain a crude product; cooling the crude product and washing it with deionized water to remove the inorganic salt, thereby obtaining the triazine aromatic amine dimer; wherein the inorganic salt is one or more of lithium bromide, lithium chloride, lithium fluoride, zinc chloride, or zinc sulfate. The structural formula of the triazine aromatic amine dimer is shown in Formula I: Formula I.

[0006] According to the above scheme, in the structural formula of the triazine aromatic amine dimer, R is -H, -CH3, -NH2, -N(CH3)2, phenyl, or tolyl.

[0007] According to the above scheme, the triazine compound monomer is 2,4-diamino-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4,6-triamino-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, or 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine.

[0008] The reaction formula is as follows: .

[0009] According to the above scheme, the mass ratio of the triazine compound monomer to the inorganic salt is 1:0.2-2.5.

[0010] According to the above scheme, the triazine compound monomer and the inorganic salt are physically mixed, such as by grinding.

[0011] According to the above scheme, the reaction temperature is 260-380℃; preferably, the reaction temperature is 280-320℃.

[0012] According to the above scheme, the high-temperature solid-phase reaction time is at least 30 minutes. Preferably, the high-temperature solid-phase reaction time is no more than 2 hours.

[0013] According to the above scheme, the high-temperature solid-state reaction can be carried out under any gaseous atmosphere. For example, the above-mentioned high-temperature solid-state reaction can be carried out under N2 atmosphere, vacuum atmosphere, air atmosphere, Ar atmosphere, H / Ar atmosphere, O2 atmosphere, and CO2 atmosphere.

[0014] According to the above plan, deionized water is used for washing, and the number of washing cycles is 1-2.

[0015] According to the above scheme, after washing and filtration, a filtrate containing inorganic salts is obtained. The filtrate is then dried to precipitate the inorganic salts for reuse.

[0016] The beneficial effects of this invention are: 1. In the preparation of triazine aromatic amine dimers, this invention involves adding an inorganic salt (lithium bromide, lithium chloride, lithium fluoride, zinc chloride, or zinc sulfate) to a triazine compound to carry out a high-temperature solid-phase reaction. The inorganic salt provides a reaction interface template, and the triazine compound monomer molecules are directionally adsorbed to the inorganic salt interface in a high-temperature environment to undergo a deamination condensation reaction, thereby improving the selectivity of the product synthesis and significantly enhancing the chemical selectivity of the triazine aromatic amine dimers in the product. Furthermore, the chemical selectivity of the dimer of 2,4,6-triamino-1,3,5-triazine increased from 0% without inorganic salts to over 82% with inorganic salts, and the chemical selectivity of other dimer products (dimers of 2,4-diamino-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, and 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine) increased from 10-30% without inorganic salts to over 95% with inorganic salts.

[0017] 2. The preparation method of the present invention does not require the use of any catalyst or organic solvent. The raw materials are cheap and readily available. The reaction conditions are mild. After the reaction is completely cooled, the product and inorganic salt become solid again. By utilizing the immiscibility of small molecules with water, inorganic salt can be removed by washing with deionized water, while retaining the target product. The product is easy to separate, and the inorganic salt can be dried and precipitated for reuse, further reducing production costs and being green and environmentally friendly. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the method for preparing the triazine aromatic amine dimer of the present invention; Figure 2 The triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine in Example 1 of this invention 1 HNMR results; Figure 3 The triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine prepared under different reaction atmospheres in Example 4 of this invention 1 HNMR results; Figure 4 The triazine aromatic amine dimer based on 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine prepared in Example 5 of this invention 1 HNMR results; Figure 5 The triazine aromatic amine dimer based on 2,4-diamino-6-dimethylamino-1,3,5-triazine prepared in Example 6 of this invention 1 HNMR results; Figure 6 The triazine aromatic amine dimer based on 2,4-diamino-6-methyl-1,3,5-triazine prepared in Example 7 of this invention 1 HNMR results; Figure 7 The triazine aromatic amine dimer based on 2,4,6-triamino-1,3,5-triazine prepared in Example 8 of this invention 1 HNMR results; Figure 8 The crude product prepared in Comparative Example 1 of this invention 1 HNMR results; Figure 9 The product prepared in Comparative Example 2 of this invention 1 HNMR results; Figure 10 The product prepared in Comparative Example 3 of this invention 1 HNMR results. Detailed Implementation

[0019] The principles and features of the present invention are described below with reference to the accompanying drawings and specific embodiments. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0020] This invention provides a method for preparing triazine aromatic amine dimers, the preparation process of which is as follows: Figure 1 As shown, triazine compound monomers and inorganic salts (one or more of lithium bromide, lithium chloride, lithium fluoride, zinc chloride, or zinc sulfate) are mixed and subjected to a high-temperature solid-phase reaction to obtain a crude product. After cooling, the inorganic salts are removed by washing with deionized water to obtain triazine aromatic amine dimers. This method introduces inorganic salts as a "dynamic active interface" to precisely guide the reaction path in the high-temperature solid-phase reaction, achieving highly selective and high-yield synthesis of triazine aromatic amine dimers. The entire process does not require organic solvents, is green and environmentally friendly, and the inorganic salts can be recycled.

[0021] The following are specific examples.

[0022] Example 1 This embodiment provides a triazine aromatic amine dimer, which is a triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine. It is formed by secondary amine bridging using 2,4-diamino-6-phenyl-1,3,5-triazine (phenylmelamine) as a monomer. Its structural formula is as follows: Preparation method: Select a clean 4ml square crucible, weigh 1g of 2,4-diamino-6-phenyl-1,3,5-triazine (phenyl melamine) and 1g of LiBr. The mass ratio of 2,4-diamino-6-phenyl-1,3,5-triazine (phenyl melamine) to LiBr is 1:1. Mix them thoroughly and place them in a tube furnace under N2 atmosphere. Keep the furnace at 260℃ for 30min to obtain crude product. Wash the crude product with distilled water 1-2 times, filter and dry it. Dry and recover the LiBr dissolved in the water for reuse. The target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine.

[0023] use 1 HNMR was used to characterize the structures of the raw materials and products, and the spectra are as follows: Figure 2 As shown in the NMR data, it is evident that no significant impurities were generated except for the target peaks of the product (ppm: 9.7 and ppm: 7.2), indicating that the reactant (ppm: 6.7) reacted completely. The yield of the product reached over 99%, and the chemoselectivity of the product was over 99%. This demonstrates that the addition of an inorganic salt component to the reactant monomer can suppress side reactions, avoid the formation of byproducts, and improve the selectivity for the formation of the triazine aromatic amine dimer of the target product 2,4-diamino-6-phenyl-1,3,5-triazine, thereby increasing the yield and chemoselectivity of the target product.

[0024] Example 2 The product provided in this embodiment is the same as that in Example 1, both being triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine. The preparation method differs from that in Example 1 in that: the amount of LiBr is 0.2g, the mass ratio of 2,4-diamino-6-phenyl-1,3,5-triazine (phenyl melamine) to LiBr is 1:0.2, the temperature is 320℃, and everything else is the same as in Example 1. A white powdery solid is obtained, and its NMR data shows that the raw materials react completely, and no other impurities are generated except for the product.

[0025] Example 3 The product provided in this embodiment is the same as that in Example 1, both being triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine. The preparation method differs from that in Example 1 in that: the amount of LiBr is 2.5g, the mass ratio of 2,4-diamino-6-phenyl-1,3,5-triazine (phenyl melamine) to LiBr is 1:2.5, the temperature is 380℃, and everything else is the same as in Example 1. A white powdery solid is obtained, and its NMR data shows that the raw materials react completely, with no obvious impurities generated except for the product.

[0026] Example 4 The product provided in this embodiment is the same as that in Example 1, both being triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine. The difference between the preparation method and that in Example 1 is that zinc chloride is used as the inorganic salt and the reaction temperature is different.

[0027] The specific preparation method is as follows: Select a clean 4ml square crucible, weigh 1g of 2,4-diamino-6-phenyl-1,3,5-triazine (phenyl melamine) and 1g of ZnCl2, mix them thoroughly and place them in a tube furnace, and divide them into 7 groups: A, B, C, D, E, F, and G. The seven groups are calcined at 260℃ for 30min under N2 atmosphere, vacuum, air atmosphere, Ar atmosphere, H2 / Ar atmosphere, CO2 atmosphere, and O2 atmosphere, respectively. After calcination, the crude product is obtained. The product is washed 3-5 times with distilled water, filtered and dried. The mixed salt dissolved in the water is dried and recovered for reuse. The target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine.

[0028] The structure of the product was characterized by ¹H NMR, and its spectra are as follows: Figure 3 As shown in the NMR data, it is evident that, apart from the target peaks of the product (ppm: 9.7 and ppm: 7.2), no significant impurities were generated. The reactant (ppm: 6.7) reacted completely, and the yield of the product exceeded 99%, with a chemiselectivity exceeding 99%. This indicates that adding an inorganic salt component to the reactant monomer can suppress side reactions, avoid the formation of byproducts, and improve the yield and chemiselectivity of the target product. Furthermore, this reaction has no special requirements for the reaction atmosphere and can be carried out in any reaction atmosphere.

[0029] Example 5 This embodiment provides a triazine aromatic amine dimer, which is a triazine aromatic amine dimer based on 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine. It is formed by secondary amine bridging using 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine as a monomer, and its structural formula is as follows:

[0030] The preparation method is as follows: Select a clean 4ml square crucible, weigh 1g of 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine and 1g of ZnCl2, mix them thoroughly and evenly, place them in a tube furnace and keep them at 260℃ for 30min under N2 atmosphere. After obtaining the crude product, wash the crude product with distilled water 1-2 times, filter and dry it, and dry and recover the ZnCl2 dissolved in the water for reuse. The target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer based on 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine.

[0031] The structure of the product was characterized by ¹H NMR, and its spectrum is shown below. Figure 4 As shown in the NMR data, it is evident that, apart from the target peak of the product (ppm: 9.7), no significant impurities were generated. The reactant (ppm: 6.7) reacted completely, and the product yield and chemiselectivity both exceeded 99%. This indicates that the addition of inorganic salt components to the reactant monomers can suppress side reactions, prevent the formation of byproducts, and improve the product yield and chemiselectivity.

[0032] Example 6 This embodiment provides a triazine aromatic amine dimer, which is a triazine aromatic amine dimer based on 2,4-diamino-6-dimethylamino-1,3,5-triazine. It is formed by secondary amine bridging using 2,4-diamino-6-dimethylamino-1,3,5-triazine as a monomer, and its structural formula is as follows:

[0033] The preparation method is as follows: Select a clean 4ml square crucible, weigh 1g of 2,4-diamino-6-dimethylamino-1,3,5-triazine and 1g of ZnCl2, mix them thoroughly and evenly, place them in a tube furnace and keep them at 260℃ for 30min under N2 atmosphere. After obtaining the crude product, wash the crude product with distilled water 3-5 times, filter and dry it, and dry and recover the ZnCl2 dissolved in the water for reuse. The target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer based on 2,4-diamino-6-dimethylamino-1,3,5-triazine.

[0034] The structure of the product was characterized by ¹H NMR, and its spectrum is shown below. Figure 5As shown in the NMR data, it is evident that, apart from the target peaks of the product (ppm: 6.5, 8.8), no significant impurities were generated. The reactant (ppm: 6.0) reacted completely, the product yield was >90%, and the chemiselectivity was over 99%. This indicates that the addition of inorganic salt components to the reactant monomers can suppress side reactions, prevent the formation of byproducts, and improve the product yield and chemiselectivity.

[0035] Example 7 This embodiment provides a triazine aromatic amine dimer, which is a triazine aromatic amine dimer based on 2,4-diamino-6-methyl-1,3,5-triazine. It is formed by secondary amine bridging using 2,4-diamino-6-methyl-1,3,5-triazine as a monomer, and its structural formula is as follows: The preparation method is as follows: Select a clean 4ml square crucible, weigh 1g of 2,4-diamino-6-methyl-1,3,5-triazine and 1g of ZnCl2, mix them thoroughly, place them in a tube furnace and keep them at 260℃ for 30min under N2 atmosphere. After obtaining the crude product, wash the crude product with distilled water 3-5 times, filter and dry it. Dry and recover the ZnCl2 dissolved in the water for reuse. The target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer based on 2,4-diamino-6-methyl-1,3,5-triazine.

[0036] The structure of the product was characterized by ¹H NMR, and its spectrum is shown below. Figure 6 As shown in the NMR data, it is clear that no impurities were generated except for the target peak of the product (ppm: 9.5). The reactant (ppm: 6.5) reacted completely, the product yield was >90%, and the chemiselectivity reached over 99%. This indicates that the addition of inorganic salt components to the reactant monomers can suppress side reactions, avoid the formation of byproducts, and improve the product yield and chemiselectivity.

[0037] Example 8 This embodiment provides a triazine aromatic amine dimer, which is a triazine aromatic amine dimer based on 2,4,6-triamino-1,3,5-triazine. It is formed by secondary amine bridging using 2,4,6-triamino-1,3,5-triazine as a monomer, and its structural formula is as follows:

[0038] The preparation method is as follows: Select a clean 4ml square crucible, weigh 1g of 2,4,6-triamino-1,3,5-triazine (melamine) and 1g of LiBr, mix them thoroughly, place them in a tube furnace and introduce N2 atmosphere, keep them at 320℃ for 60min to obtain crude product, wash the crude product with distilled water 1-2 times, filter and dry, dry and recover the LiBr dissolved in water for reuse, the target product obtained by filtration is a white powder solid, which is the triazine aromatic amine dimer of 2,4,6-triamino-1,3,5-triazine.

[0039] The crude product was white, with a yield of approximately 95%. The structures of melamine and the obtained crude product were characterized by ¹H NMR and compared with the dimer obtained in Example 8. The spectra are shown below. Figure 7 As shown in the spectral analysis, the chemical selectivity of the triazine aromatic amine dimer of 2,4-diamino-6-phenyl-1,3,5-triazine in the product is 82%, with a small amount of unreacted monomers and the byproduct melleramine.

[0040] Comparative Example 1 The product provided in this comparative example is the same as that in Example 1, both being triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine, formed by secondary amine bridging using 2,4-diamino-6-phenyl-1,3,5-triazine (phenylmelamine) as the monomer. However, its preparation method differs from that in Example 1, in that the inorganic salt LiBr was not added in this example. The specific preparation method is as follows: (1) Weigh 1g of phenyl melamine, place it in a tube furnace and introduce N2 atmosphere, keep it at 320℃ for 30min, and obtain crude product after the heat preservation is completed; The crude product was yellow. The structures of the raw material benzotrimelamine and the obtained crude product were characterized by ¹H NMR and compared with the dimer of benzotrimelamine obtained in Example 1. The spectra are shown below. Figure 8 As shown in the spectral analysis, in addition to the dimer of benzomelamine, the product also contains unreacted benzomelamine monomer and benzomelamine trimer. The yield of the crude product of the whole reaction is about 90%, and the chemical selectivity of the triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine in the crude product is 42%.

[0041] (2) The crude product obtained above was washed with ethyl acetate to remove the accompanying yellow product (trimer of benzomelamine) to obtain a precipitate. The precipitate was then washed with methanol 2-3 times to remove the benzomelamine monomer and obtain another precipitate. The precipitate was further washed and filtered to obtain a benzomelamine dimer with higher chemical selectivity, namely a triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine. The chemical selectivity of the triazine aromatic amine dimer based on 2,4-diamino-6-phenyl-1,3,5-triazine was 93%.

[0042] Comparative Example 2 The product provided in this comparative example is the same as that in Example 1, both being triazine aromatic amine dimers based on 2,4-diamino-6-phenyl-1,3,5-triazine. The preparation method differs from that in Example 1 in that the amount of LiBr is 0.1 g, the mass ratio of benzomelamine to LiBr is 10:1, and all other aspects are the same as in Example 1, resulting in a white powdery solid.

[0043] The structure of the product was characterized by ¹H NMR, and its spectrum is shown below. Figure 9 As shown in the NMR data, it is clear that due to insufficient salt content, although no other impurities were generated besides the target peak of the product (ppm: 9.7), most of the raw materials (ppm: 6.7) had not reacted completely. However, this demonstrates that adding inorganic salt components can suppress side reactions and prevent the formation of byproducts.

[0044] Comparative Example 3 The product provided in this comparative example, like that in Example 8, is a triazine aromatic amine dimer based on 2,4,6-triamino-1,3,5-triazine (melamine). The difference in preparation method compared to Example 8 is that no inorganic salt, LiBr, was added in this example. The specific preparation method is as follows: 1g of melamine was weighed and placed in a tube furnace under a N2 atmosphere, then calcined at 360°C for 60 minutes. The crude product was obtained upon completion of calcination.

[0045] The crude product was white. The structures of melamine and the crude product were characterized by ¹H NMR and compared with the dimer obtained in Example 8. The spectra are shown below. Figure 10 As shown in the spectral analysis, the product is melamine and unreacted melamine monomer. No triazine aromatic amine dimer of 2,4-diamino-6-phenyl-1,3,5-triazine was found to be produced, and its chemical selectivity is 0%.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a triazine aromatic amine dimer, characterized in that, The triazine compound monomer and inorganic salt are mixed and subjected to a high-temperature solid-state reaction to obtain a crude product. The inorganic salt is then washed to remove the crude product, thereby obtaining the triazine aromatic amine dimer. The inorganic salt is one or more of lithium bromide, lithium chloride, lithium fluoride, zinc chloride, and zinc sulfate. The structural formula of the triazine aromatic amine dimer is shown in Formula I: Formula I.

2. The method for preparing the triazine aromatic amine dimer according to claim 1, characterized in that, In the structural formula of the triazine aromatic amine dimer, R is -H, -CH3, -NH2, -N(CH3)2, phenyl, or tolyl.

3. The method for preparing the triazine aromatic amine dimer according to claim 2, characterized in that, The triazine compound monomer is 2,4-diamino-1,3,5-triazine, 2,4-diamino-6-methyl-1,3,5-triazine, 2,4,6-triamino-1,3,5-triazine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, or 2,4-diamino-6-(4-methylphenyl)-1,3,5-triazine.

4. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, The mass ratio of the triazine compound monomer to the inorganic salt is 1:0.2-2.

5.

5. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, The temperature range for high-temperature solid-phase reactions is 260-380℃.

6. The method for preparing triazine aromatic amine dimers according to claim 4, characterized in that, The temperature range for high-temperature solid-phase reactions is 280-320℃.

7. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, The high-temperature solid-phase reaction time is at least 30 minutes.

8. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, High-temperature solid-state reactions can be carried out in any gaseous atmosphere.

9. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, Wash 1-2 times.

10. The method for preparing triazine aromatic amine dimers according to claim 1, characterized in that, After washing and filtration, a filtrate containing inorganic salts is obtained. The filtrate is then dried to precipitate the inorganic salts for reuse.

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