Phosphorus-based dendritic macromolecular compound and preparation method thereof

Abstract

The preparation method comprises the following steps: adding a 1-hydroxyalkyl phosphonic acid diester monomer and a catalyst into a reaction kettle, stirring, reacting to obtain a 1-hydroxyalkyl phosphonic acid diester dendritic macromolecular compound crude product, and concentrating under reduced pressure to obtain the phosphorus-based dendritic macromolecular compound. And removing a low-molecular alcohol byproduct in the reaction to obtain the phosphorus-based dendritic macromolecular compound. According to the invention, the raw material 1-hydroxyalkyl phosphonic acid diester compound is used for self transesterification, the catalyst which is cheap and easy to obtain is used for catalyzing the reaction, the operation is simple and convenient, and the 1-hydroxyalkyl phosphonic acid diester dendritic macromolecular compound is synthesized with higher phosphorus content.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a phosphorus-based dendritic macromolecular compound and its preparation method. Background Technology

[0002] 1-Hydroxyalkylphosphonic acid diesters are an important class of intermediates and raw materials, and have received much attention and have wide applications in flame retardants, pharmaceuticals and other fields.

[0003] In recent years, with the increasing emphasis on environmental protection by the state, halogenated flame retardants have been banned. Phosphorus-based flame retardants, due to their low smoke emission, low toxicity, low pollution, and better compatibility and thermal stability with polymers, have become one of the most widely used flame retardants in modern applications. Among them, phosphorus-based dendritic macromolecular compounds have attracted much attention due to their advantages such as minimal impact on the physical and mechanical properties of products, improvement of material mechanical properties, and long-lasting flame retardant performance. For example, patent CN105504352 B discloses a phosphorus-nitrogen-based dendritic macromolecular functionalized graphene flame retardant, which solves the dispersion problem of flame retardants in polymer materials and improves the flame retardant effect of flame retardants on polymers. However, its application is limited to graphene materials, failing to fully realize the material's application value. Patent CN 113402707 A discloses a preparation method for a dendritic nitrogen-phosphorus flame retardant, solving the technical problems of complex preparation processes and limited flame retardant effects of existing dendritic phosphorus-nitrogen-based flame retardants. However, the synthesis involves various solvents and acid-binding agents, which is detrimental to environmental protection.

[0004] Dendritic macromolecular compounds can be more effectively dispersed in materials, forming a more uniform flame-retardant layer, thereby improving the flame-retardant effect. Furthermore, phosphorus-based flame retardants have advantages such as low smoke and non-toxicity, meeting environmental protection requirements. Therefore, developing a novel preparation process for phosphorus-based dendritic macromolecular flame-retardant materials has significant practical application value. In this invention, we selected 1-hydroxyalkylphosphonic acid diester monomers as starting materials and developed a method for preparing 1-hydroxyalkylphosphonic acid diester dendritic macromolecular compounds via self-transesterification. This method requires no additional solvents, and the synthesized product has a high phosphorus content. It is a green and environmentally friendly synthetic process for preparing phosphorus-based dendritic macromolecular compounds. The prepared 1-hydroxyalkylphosphonic acid diester dendritic macromolecular compounds have potential application value in phosphorus-containing flame retardancy. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a phosphorus-based dendritic macromolecular compound and its preparation method.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a phosphorus-based dendritic macromolecular compound, characterized in that: the chemical structure of the phosphorus-based dendritic macromolecular compound is shown in formula (1):

[0009]

[0010] Wherein, R1 is selected from hydrogen, straight-chain or branched alkyl groups of C1 to C19, and the branched group includes, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and alkyl groups of C1 to C19; R2 is selected from straight-chain or branched alkyl groups of C1 to C20, and the branched group includes, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and alkyl groups of C1 to C20.

[0011] As a preferred embodiment of the phosphorus-based dendritic macromolecular compound of the present invention, the total phosphorus content ranges from 15% to 30%.

[0012] Another objective of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a phosphorus-based dendritic macromolecular compound, comprising: adding a 1-hydroxyalkylphosphonic acid diester monomer and a catalyst to a reaction vessel and stirring; after the reaction, obtaining a crude product of a 1-hydroxyalkylphosphonic acid diester dendritic macromolecular compound; then concentrating under reduced pressure to remove low-molecular-weight alcohol byproducts from the reaction to obtain the phosphorus-based dendritic macromolecular compound.

[0013] In a preferred embodiment of the preparation method described in this invention, the 1-hydroxyalkylphosphonate diester monomers include dimethyl hydroxymethylphosphonate and dimethyl 1-hydroxypropylphosphonate; the catalysts include solid base catalysts, organic base catalysts, and Lewis acid catalysts.

[0014] In a preferred embodiment of the preparation method described in this invention, the solid base catalyst includes anhydrous potassium carbonate and anhydrous sodium carbonate.

[0015] In a preferred embodiment of the preparation method described in this invention, the organic base catalyst includes triethylamine, diisopropylethylamine, and imidazole.

[0016] In a preferred embodiment of the preparation method described in this invention, the Lewis acid catalyst is anhydrous magnesium chloride.

[0017] In a preferred embodiment of the preparation method described in this invention, the equivalent ratio of 1-hydroxyalkylphosphonic acid diester monomer to catalyst is 1:0.02-0.10.

[0018] In a preferred embodiment of the preparation method described in this invention, the equivalent ratio of 1-hydroxyalkylphosphonic acid diester monomer to catalyst is 1:0.05.

[0019] In a preferred embodiment of the preparation method described in this invention, the reaction temperature is 150–210°C and the reaction time is 10–25 h.

[0020] Beneficial effects of this invention:

[0021] This invention utilizes a 1-hydroxyalkylphosphonic acid diester compound as a raw material for self-esterification reaction, and uses an inexpensive and readily available catalyst to catalyze the reaction. The operation is simple, and a 1-hydroxyalkylphosphonic acid diester dendritic macromolecular compound is synthesized with a high phosphorus content. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0023] Figure 1 This is a flowchart illustrating the preparation process of dimethyl hydroxymethylphosphonate dendritic macromolecular compound 1 in Example 1 of the present invention.

[0024] Figure 2 This is a flowchart illustrating the preparation process of dimethyl hydroxymethylphosphonate dendritic macromolecular compound 2 in Example 2 of the present invention.

[0025] Figure 3 This is a flowchart illustrating the preparation process of dimethyl hydroxymethylphosphonate dendritic macromolecular compound 3 in Example 3 of the present invention.

[0026] Figure 4 Phosphorus spectrum characterization of dimethyl hydroxymethylphosphonate dendritic macromolecule 1 in Example 1 of the present invention.

[0027] Figure 5 Phosphorus spectrum characterization of the hydroxymethylphosphonic acid dimethyl ester dendritic macromolecule compound 2 in Example 2 of the present invention. Detailed Implementation

[0028] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0030] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0031] Unless otherwise specified, all raw materials used in the embodiments of this invention are commercially available.

[0032] Thermogravimetric analysis:

[0033] 1) GB / T 27761 (Chinese National Standard): Similar to ISO 11358, applicable to the analysis of thermal stability of materials.

[0034] 2) Sample preparation

[0035] a. Sample amount: usually 5-20mg, which should be evenly spread in the crucible to avoid accumulation.

[0036] Morphological requirements: Powders or films must be kept loose, and block samples must be cut into small pieces.

[0037] Pretreatment: Drying may be required to remove moisture (depending on the material).

[0038] b. Instrument calibration

[0039] Temperature calibration: Use magnetic standard materials (such as the Curie point of nickel-cobalt alloys) or materials with known melting points (such as indium-tin).

[0040] Weight calibration: Standard weights are used to calibrate the balance sensitivity to ensure accurate mass measurement.

[0041] c. Experimental parameter settings

[0042] Heating rate: commonly 5-20℃ / min, which affects the resolution of decomposition temperature.

[0043] Atmosphere: Inert (N2, Ar) or oxidizing (O2, air), flow rate 20-100 mL / min.

[0044] Temperature range: typically room temperature to 800℃ (adjusted according to the temperature resistance of the material).

[0045] d. Test execution

[0046] The sample is loaded into the furnace, the heating program is started, and the mass change is recorded simultaneously.

[0047] Real-time monitoring of thermogravimetric (TG) curves.

[0048] e. Closure and Cleaning

[0049] After cooling to a safe temperature, remove the sample and clean the crucible to avoid residues affecting subsequent experiments.

[0050] Example 1

[0051] This invention provides a method for preparing phosphorus-based dendritic macromolecular compounds:

[0052] In a 1L reactor, dimethyl 1-hydroxymethylphosphonate (560.3g, 4mol) and anhydrous magnesium chloride (19.0g, 0.2mol) were added sequentially. The mixture was heated to 185℃ and reacted for 10h. After the reaction was completed, the mixture was concentrated under reduced pressure to remove the byproduct methanol, yielding dendritic macromolecular compound 1 with a total phosphorus content of 25.1%.

[0053] Figure 1 For the preparation process, Figure 4 As shown, the methylene group in dimethyl 1-hydroxymethylphosphonate will always be present in the system, while the terminal methyl group of the ester group in dimethyl hydroxymethyl phosphate will generate methanol as the reaction proceeds. The generated methanol is collected in the water separator through the water separator, thereby reducing the number of methyl hydrogen atoms in the reaction system. As can be seen in the NMR spectrum, as the reaction proceeds, the ratio of methylene hydrogen atoms to methyl hydrogen atoms becomes 100:44. The decrease in ratio means that the reaction proceeds and the target polymerization product is generated—a dendritic macromolecular compound 1.

[0054] Example 2

[0055] In a 1L reactor, dimethyl 1-hydroxymethylphosphonate (560.3g, 4mol) and anhydrous magnesium chloride (19.0g, 0.2mol) were added sequentially. The mixture was heated to 185℃ and reacted for 20h. After the reaction was completed, the mixture was concentrated under reduced pressure to remove the byproduct methanol, yielding dendritic macromolecular compound 2 with a total phosphorus content of 27.0%.

[0056] Figure 2 For the preparation process, such as Figure 5As shown, the methylene group in dimethyl 1-hydroxymethylphosphonate will always be present in the system, while the terminal methyl group of the ester group in dimethyl 1-hydroxymethylphosphonate will generate methanol as the reaction proceeds. The generated methanol is collected in the water separator through the water separator, thereby reducing the number of methyl hydrogen atoms in the reaction system. As can be seen in the NMR spectrum, as the reaction proceeds, the ratio of methylene hydrogen atoms to methyl hydrogen atoms becomes 100:34. The decrease in ratio means that the reaction proceeds and the target polymerization product is generated—a dendritic macromolecular compound 2.

[0057] Example 3

[0058] In a 1L reactor, 1-hydroxypropylphosphonic acid dimethyl ester (672.6g, 4mol) and anhydrous magnesium chloride (19.0g, 0.2mol) were added sequentially, and the mixture was heated to 185℃ and reacted for 10h. After the reaction was completed, the mixture was concentrated under reduced pressure to remove the byproduct methanol, yielding dendritic macromolecular compound 3 with a total phosphorus content of 20.2%. Figure 3 The preparation process is as described in Example 3.

[0059] Comparative Example 1

[0060] The monomer 1-hydroxymethylphosphonic acid dimethyl ester was used as a control for analysis.

[0061] Thermogravimetric analysis (TGA) results of dimethyl hydroxymethylphosphonate and its dendritic macromolecules are shown in Table 2:

[0062] Table 2

[0063]

[0064]

[0065] The maximum mass loss rate of dimethyl hydroxymethylphosphonate was 222°C, while the maximum mass loss rate of the phosphorus-based dendritic macromolecular compound 1 in Example 1 increased to 369°C, demonstrating its good thermal stability. With prolonged reaction time, the temperature at which each percentage of mass loss occurred increased significantly. Furthermore, the high residual carbon content allowed for more complete adhesion to the material surface, isolating it from air and thus contributing to flame retardancy. Therefore, dimethyl hydroxymethylphosphonate dendritic macromolecular compound is a material with potential flame retardant properties.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the present invention.

Claims

1. A phosphorus-based dendritic macromolecular compound, characterized in that: The chemical structures of phosphorus-based dendritic macromolecules are shown in formula (1): Wherein, R1 is selected from hydrogen, straight-chain or branched alkyl groups of C1 to C19, and the branched group includes, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and alkyl groups of C1 to C19; R2 is selected from straight-chain or branched alkyl groups of C1 to C20, and the branched group includes, but is not limited to, methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, and alkyl groups of C1 to C20.

2. The phosphorus-based dendritic macromolecular compound as described in claim 1, characterized in that: The total phosphorus content ranges from 15% to 30%.

3. The method for preparing the phosphorus-based dendritic macromolecular compound as described in claim 1, characterized in that: The process involves adding 1-hydroxyalkylphosphonic acid diester monomers and catalysts to a reaction vessel and stirring. After the reaction, a crude product of 1-hydroxyalkylphosphonic acid diester dendritic macromolecular compound is obtained. The product is then concentrated under reduced pressure to remove low-molecular-weight alcohol byproducts from the reaction, thus obtaining the phosphorus-based dendritic macromolecular compound.

4. The preparation method according to claim 3, characterized in that: 1-Hydroxyalkylphosphonic acid diesters include dimethyl hydroxymethylphosphonate and dimethyl 1-hydroxypropylphosphonate; catalysts include solid base catalysts, organic base catalysts and Lewis acid catalysts.

5. The preparation method according to claim 4, characterized in that: Solid base catalysts include anhydrous potassium carbonate and anhydrous sodium carbonate.

6. The preparation method according to claim 4, characterized in that: Organic base catalysts include triethylamine, diisopropylethylamine, and imidazole.

7. The preparation method according to claim 4, characterized in that: The Lewis acid catalyst is anhydrous magnesium chloride.

8. The preparation method according to claim 2, characterized in that: The equivalent ratio of 1-hydroxyalkylphosphonic acid diester monomer to catalyst is 1:0.02 to 0.

10.

9. The preparation method according to claim 2, characterized in that: The equivalent ratio of 1-hydroxyalkylphosphonic acid diester monomer to catalyst is 1:0.

05.

10. The preparation method according to claim 2, characterized in that: The reaction temperature is 150–210℃, and the reaction time is 10–25 h.

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