Organic aluminum phosphite as well as preparation method and application thereof

Abstract

The invention provides organic aluminum phosphite as well as a preparation method and application thereof, and the preparation method comprises the following steps: (1) hydrolyzing organic phosphite ester serving as a raw material under an acidic condition to obtain organic phosphorous acid; and (2) mixing the organic phosphorous acid prepared in the step (1) with an aluminum-containing compound, reacting at 100-200 DEG C under an acidic condition and a water medium, and then performing post-treatment to obtain the organic aluminum phosphite, the organic phosphite ester is dimethyl methylphosphate; the preparation method of the dimethyl methylphosphate comprises the following steps: under the protection of inert gas, mixing and stirring trimethyl phosphite serving as a raw material and a phenyl sulfonic acid catalyst, and carrying out rearrangement reaction in a pressurizing and heating manner, so as to synthesize the target product dimethyl methylphosphate. The organic aluminum phosphite provided by the invention has excellent thermal stability, and the initial decomposition temperature is not lower than 360 DEG C; the compound can be used as a flame-retardant synergist, and can be compounded with a flame retardant to be used as a flame-retardant system of a high polymer material.

Description

Technical Field

[0001] The invention belongs to the technical field of organic matter preparation, and particularly relates to an organic aluminum phosphite, a preparation method and application thereof. Background Art

[0002] Organoaluminum phosphites are a class of compounds that typically contain an organic group and an aluminum phosphite structure. These compounds can be used as flame retardants or flame retardant synergists and have found applications in polymer materials due to their unique properties.

[0003] One method for preparing organoaluminum phosphites is to dissolve phosphorous acid or its salt in an aqueous solution, then add a modifier and stir, allowing a specific chemical reaction to form the target compound. Organoaluminum phosphites are sometimes prepared by chemical reactions using specific organic groups and aluminum sources.

[0004] Flame-retardant polymer molding compounds are plastic materials designed to slow or prevent the spread of flames. These materials are widely used in various industries, including automotive, electronics, construction, and aerospace, to meet safety standards and fire protection requirements. Flame-retardant polymers can achieve flame retardancy through several different mechanisms: Physical barrier: Forming a non-combustible physical layer that isolates oxygen and reduces heat transfer. Thermal stability: Improving the thermal stability of the polymer and reducing the generation of flammable gases during thermal decomposition. Gas phase interaction: Release of inert gases during combustion, diluting the concentration of flammable gases. Condensed phase interaction: Modifying the chemical properties of the polymer surface, reducing the formation of flammable substances. Common flame retardants include, but are not limited to: Halogen flame retardants (such as bromides and chlorides): Suppress flames by generating hydrogen halide gas. Phosphorus-based flame retardants (such as phosphates and phosphites): Forming a protective carbonized layer that isolates oxygen. Inorganic flame retardants (such as aluminum hydroxide and magnesium hydroxide): Dissipating heat and releasing water vapor through endothermic reactions. Metal salts (such as antimony and zinc compounds): usually used in combination with other flame retardants to enhance the flame retardant effect.

[0005] Organoaluminum phosphites, when used as flame retardant synergists in combination with flame retardants, can enhance the flame retardancy of polymer molding materials. They can be used in glass fiber-reinforced engineering plastics such as PA66, PA6, and PBT, as well as elastomers and other polymers. Organoaluminum phosphites exhibit excellent thermal stability, meaning they remain stable at high temperatures and resist decomposition.

[0006] These compounds can also improve the dispersibility of polymer composites, helping to improve the mechanical and processing properties of the materials. Triethylaluminum phosphite (TEPA) is a specific organoaluminum phosphite compound. It is a colorless liquid that can be used as a catalyst in a variety of organic reactions.

[0007] At present, in order to obtain organic aluminum phosphite solid, aluminum phosphite is mostly prepared by hydrothermal method, which is prepared by reaction crystallization under high temperature and high pressure for a long time. In addition, an organic template needs to be added for the reaction, and this preparation method is inefficient. Summary of the Invention

[0008] The purpose of the present invention is to provide an organic aluminum phosphite, a preparation method and application thereof.

[0009] In order to achieve the above object, the present invention provides the following technical solutions: A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 100-200° C. in an acidic aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0010] Furthermore, in step (1), the organic phosphite is dimethyl methyl phosphate.

[0011] Furthermore, the preparation method of dimethyl methyl phosphate is as follows: under the protection of inert gas, the raw material trimethyl phosphite and a phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and its amount is 3-5% of the molar number of the raw material trimethyl phosphite.

[0012] Furthermore, the pressure of the pressurized heating reaction system is 2 to 6 atmospheres, and the reaction temperature is 120 to 180°C.

[0013] Furthermore, the pressure of the pressurized heating reaction system is 2 to 6 atmospheres, the temperature is 120 to 180° C., and the reaction time is 2 to 6 hours.

[0014] Furthermore, after synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation, and the distillation residue mainly contains dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester mixture, and the distillation residue can be recycled.

[0015] Furthermore, in step (2), the aluminum-containing compound is metallic aluminum.

[0016] Furthermore, the molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:1.8-2.3; Furthermore, the molar ratio of the organic phosphorous acid to water is 1:2.2-2.5.

[0017] Furthermore, in step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0018] The present invention also provides an organic aluminum phosphite prepared by the above preparation method.

[0019] The present invention also provides the application of the organic aluminum phosphite prepared by the above preparation method.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention provides an organic aluminum phosphite with excellent thermal stability and an initial decomposition temperature of not less than 360°C; it can be used as a flame retardant synergist and compounded with a flame retardant to form a flame retardant system for polymer materials.

[0021] 2. The present invention uses an organic phosphite as a raw material, obtains organic phosphorous acid by hydrolysis, and then reacts with an aluminum-containing compound to prepare an organic aluminum phosphite. The purity of the raw material has an important influence on the yield and purity of the final product. Step (1): Hydrolysis to obtain organic phosphorous acid. High-purity organic phosphite means fewer impurities, which reduces the side reactions that may occur during the hydrolysis process. The presence of impurities may lead to the formation of by-products, such as hydrolysis by-products of esters, other types of organic acids, etc., which may affect subsequent reactions. High-purity raw materials help to better control the conditions during the hydrolysis process, such as temperature, pH value, etc., which helps to obtain higher-purity organic phosphorous acid. High-purity raw materials can make the reaction more consistent and predictable, thereby improving the quality of the final product. Step (2): Preparation of organic aluminum phosphite. High-purity organic phosphorous acid can reduce the side reactions that may occur when reacting with an aluminum-containing compound. Impurities may react with the aluminum-containing compound to form unwanted by-products, thereby affecting the yield and purity of the final product. High-purity organophosphorous acid allows for better control of reaction conditions, such as temperature and pH, which helps maintain a stable reaction environment, thereby improving the yield and purity of the final product. Reactions under acidic conditions can lead to unstable reaction conditions if the raw materials contain basic impurities, affecting yield. High-purity organophosphorous acid helps reduce impurities in the final product, thereby improving product purity. The presence of impurities can lead to the appearance of unwanted components in the final product, affecting its performance. DETAILED DESCRIPTION

[0022] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0023] Example 1 This embodiment provides a method for preparing an organic aluminum phosphite, which comprises the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 150° C. in an acidic condition and an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0024] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0025] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 4% of the molar number of the raw material trimethyl phosphite.

[0026] The pressure of the pressurized heating reaction system was 2 atmospheres, the temperature was 160° C., and the reaction time was 4 hours.

[0027] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0028] In step (2), the aluminum-containing compound is metallic aluminum.

[0029] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:2; The molar ratio of the organic phosphorous acid to water is 1:2.3.

[0030] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0031] Example 2 A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 100° C. under acidic conditions and in an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0032] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0033] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 3% of the molar number of the raw material trimethyl phosphite.

[0034] The pressure of the pressurized heating reaction system was 2 atmospheres, the temperature was 150° C., and the reaction time was 4 hours.

[0035] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0036] In step (2), the aluminum-containing compound is metallic aluminum.

[0037] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:1.8; The molar ratio of the organic phosphorous acid to water is 1:2.2.

[0038] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0039] Example 3 A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 200° C. in an acidic aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0040] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0041] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 5% of the molar number of the raw material trimethyl phosphite.

[0042] The pressure of the pressurized heating reaction system was 4 atmospheres, the temperature was 160° C., and the reaction time was 6 hours.

[0043] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0044] In step (2), the aluminum-containing compound is metallic aluminum.

[0045] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:2.3; The molar ratio of the organic phosphorous acid to water is 1:2.5.

[0046] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0047] Example 4 A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 100° C. under acidic conditions and in an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0048] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0049] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 5% of the molar number of the raw material trimethyl phosphite.

[0050] The pressure of the pressurized heating reaction system was 2 atmospheres, and the reaction temperature was 180°C.

[0051] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0052] In step (2), the aluminum-containing compound is metallic aluminum.

[0053] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:1.8; The molar ratio of the organic phosphorous acid to water is 1:2.5.

[0054] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0055] Comparative Example 1 The difference between this comparative example and Example 1 is that the pressure of the pressurized heating reaction system is 1 atmosphere, the temperature is 110° C., and the reaction time is 2 hours.

[0056] A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 150° C. in an acidic condition and an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0057] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0058] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 4% of the molar number of the raw material trimethyl phosphite.

[0059] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0060] In step (2), the aluminum-containing compound is metallic aluminum.

[0061] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:2; The molar ratio of the organic phosphorous acid to water is 1:2.3.

[0062] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0063] Comparative Example 2 The difference between this comparative example and Example 1 is that the molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:1.3.

[0064] A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 150° C. in an acidic condition and an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0065] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0066] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 4% of the molar number of the raw material trimethyl phosphite.

[0067] The pressure of the pressurized heating reaction system was 2 atmospheres, the temperature was 160° C., and the reaction time was 4 hours.

[0068] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0069] In step (2), the aluminum-containing compound is metallic aluminum.

[0070] The molar ratio of the organic phosphorous acid to water is 1:2.3.

[0071] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0072] Comparative Example 3 The difference between this comparative example and Example 1 is that the molar ratio of the organic phosphorous acid to water is 1:1.5.

[0073] A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 150° C. in an acidic condition and an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0074] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0075] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 4% of the molar number of the raw material trimethyl phosphite.

[0076] The pressure of the pressurized heating reaction system was 2 atmospheres, the temperature was 160° C., and the reaction time was 4 hours.

[0077] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0078] In step (2), the aluminum-containing compound is metallic aluminum.

[0079] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:2; In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0080] Comparative Example 4 The difference between this comparative example and Example 1 is that the organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 80° C. under acidic conditions and in an aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0081] A method for preparing an organic aluminum phosphite, comprising the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) The organic phosphorous acid prepared in step (1) is mixed with an aluminum-containing compound, reacted at 80° C. in an acidic aqueous medium, and then post-treated to obtain the organic aluminum phosphite.

[0082] In step (1), the organic phosphite is dimethyl methyl phosphate.

[0083] The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and a rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate; the phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 4% of the molar number of the raw material trimethyl phosphite.

[0084] The pressure of the pressurized heating reaction system was 2 atmospheres, the temperature was 160° C., and the reaction time was 4 hours.

[0085] After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

[0086] In step (2), the aluminum-containing compound is metallic aluminum.

[0087] The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:2; The molar ratio of the organic phosphorous acid to water is 1:2.3.

[0088] In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

[0089] Performance Testing The products of Examples 1-4 and Comparative Examples 1-4 were subjected to performance tests, and the results are shown in Table 1.

[0090] Table 1 Performance test results

[0091] As can be seen from the above performance test results, the products of Examples 1-4 have high purity and high yield, and the comprehensive performance of Example 1 is particularly outstanding. However, since the comparative examples do not adopt the necessary technical solutions, their performance in the corresponding performance tests is significantly worse than that of the examples. The above experimental results further demonstrate the importance of the technical solutions defined in the present invention for its technical effects.

[0092] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an organic aluminum phosphite, characterized in that: The preparation method comprises the following steps: (1) Using organic phosphite as raw material, hydrolyzing under acidic conditions to obtain organic phosphorous acid; (2) mixing the organic phosphorous acid prepared in step (1) with an aluminum-containing compound, reacting them under acidic conditions in an aqueous medium at 100-200° C., and then post-treating to obtain the organic aluminum phosphite; The organic phosphite is dimethyl methyl phosphate. The preparation method of dimethyl methyl phosphate comprises the following steps: under the protection of inert gas, raw material trimethyl phosphite and phenylsulfonic acid catalyst are mixed and stirred, and rearrangement reaction is carried out by pressurized heating to synthesize the target product dimethyl methyl phosphate. The phenylsulfonic acid catalyst used is benzenesulfonic acid, p-toluenesulfonic acid and dodecylbenzenesulfonic acid, and the amount thereof is 3-5% of the molar number of the raw material trimethyl phosphite.

2. The method for preparing an organic aluminum phosphite according to claim 1, wherein: The pressure of the pressurized heating reaction system is 2 to 6 atmospheres, and the reaction temperature is 120 to 180°C.

3. The method for preparing an organic aluminum phosphite according to claim 1, wherein: The pressure of the pressurized heating reaction system is 2 to 6 atmospheres, the temperature is 120 to 180° C., and the reaction time is 2 to 6 hours.

4. The method for preparing an organic aluminum phosphite according to claim 1, wherein: After synthesizing the target product dimethyl methyl phosphate, the product is purified by vacuum distillation. The distillation residue mainly contains a mixture of dimethyl methyl phosphate, methylphosphonic acid, the corresponding benzenesulfonic acid and methyl ester, and the distillation residue can be recycled.

5. The method for preparing an organic aluminum phosphite according to claim 1, wherein: In step (2), the aluminum-containing compound is metallic aluminum.

6. The method for preparing an organic aluminum phosphite according to claim 1, characterized in that: The molar ratio of the organic phosphorous acid to the aluminum-containing compound is 3:1.8-2.

3.

7. The method for preparing an organic aluminum phosphite according to claim 1, characterized in that: The molar ratio of the organic phosphorous acid to water is 1:2.2-2.

5.

8. The method for preparing an organic aluminum phosphite according to claim 1, characterized in that: In step (2), the post-treatment is specifically: filtering, washing and drying the suspension after the reaction, and then crushing it to a certain particle size.

9. An organic aluminum phosphite prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the organic aluminum phosphite prepared according to the preparation method according to any one of claims 1 to 8.

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