A method for synthesizing sodium 2,2'-methylenebis(4,6-di-tert-butylphenyl) phosphate

Abstract

The application provides a synthesis method of 2,2'-methylene bis (4,6-di-tert-butylphenyl) sodium phosphate. In the synthesis step of the phosphate, the application innovatively introduces a basic eutectic solvent instead of the existing organic solvent + acid binding agent scheme of the prior art, which has a good catalytic effect on the reaction of bisphenol and phosphorus oxychloride. The solubility of the product phosphate in the basic eutectic solvent is low, and it is basically insoluble at room temperature, so it can be precipitated from the reaction system and promote the formation of phosphate. The obtained phosphate can be directly used in the next salt formation reaction without purification, and the yield and purity of the final product are high. The method of the application is simple and easy to operate, environmentally friendly and efficient, and is expected to be popularized and used in industry.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering, and more specifically, to a method for synthesizing sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate. Background Technology

[0002] Nucleating agents are chemical additives that accelerate the crystallization rate and improve the crystallinity of polymers. They alter the behavior of polymers during crystallization, thereby changing the morphology of the crystals and ultimately improving their thermodynamic, optical, and physicomechanical properties. As a polymer material modifier, nucleating agents broaden the application fields by improving the performance of polymer products, and are currently recognized as one of the simplest and most effective methods for polymer modification. With the continuous expansion of the application fields of modified polymers, such as modified polypropylene, and the increasing market demand, research on nucleating agents has become a hot topic in domestic and international research.

[0003] Sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate (trade name NA-11) is an important nucleating agent for polypropylene crystallization modification. Its nucleating properties are good in both enhancing transparency and rigidity, and it has good thermal stability. Compared with other organic nucleating agents (such as sorbitol derivatives, rosin resins, metal carboxylic acid salts, and polymers), it can better modify the properties of polypropylene products. Therefore, it is widely used in the processing of highly crystalline transparent polypropylene.

[0004] The synthesis of sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate involves three steps: 1. Preparation of 2,2′-methylene-bis(4,6-di-tert-butylphenol), mainly through paraformaldehyde method (e.g., Marco C, Gomez MA, Ellis G, et al. Analysis of the isothermal crystallization of isotactic polypropylene nucleated with sorbitol derivatives. Appl Polym Sci, 2003, 88(9): 2261~2274), formaldehyde aqueous solution (e.g., Marco C, Gomez MA, Ellis G, et al. Activity of α,β-nucleating agent for isotactic polypropylene and its influence on polymorphic transitions. Appl Polym Sci, 2002, 86(3): 531~539), and methylal method (Xie Fei, Zhang Xiangfu. Crystallization behavior and mechanical properties of nucleated toughened polypropylene[J]. China). Synthetic Bubber Industry, 2000, 23(6):376), the yields of the latter two are above 95%; II. Preparation of 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate, the main methods are: 1, using bisphenol and POBr3 as raw materials, using N,N-dimethylformamide as solvent, bisphenol and POBr3 undergo esterification reaction in the solvent N,N-dimethylformamide to generate brominated phosphate, and then add glacial acetic acid and water to the reaction system for hydrolysis reaction, and the target product phosphate ester can be obtained (Li Xiuyun. Polypropylene nucleating agents NA-11 and NA-2 1. Synthesis research. Hebei University of Technology: Applied Chemistry, 2006), but it has shortcomings such as difficulty in controlling the reaction temperature, low product yield, and high cost; 2. Using bisphenol and POCl3 as raw materials, using non-polar or polar solvents, and triethylamine as an acid-binding agent, bisphenol and POCl3 undergo esterification reaction to generate chlorophosphate ester, and then water / glacial acetic acid is added to the reaction system for hydrolysis reaction to obtain the target product phosphate ester (e.g. Tang Wenxiu. Synthesis and properties of organophosphate nucleating agents. Daqing Petroleum Institute: 2008; Zhang Yipeng. Preparation of transparent PP special material and its crystallization behavior study).(Dalian University of Technology: 2005). This method yields a product with improved yield and purity compared to the previous method, but still suffers from problems such as a yellowish product color and complicated post-processing. III. 2,2′-Methylene-bis(4,6-di-tert-butylphenyl) phosphate reacts with a base to form a sodium salt.

[0005] The synthesis process of sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate still has shortcomings, and there is an urgent need to find more efficient methods to prepare sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl)phosphate. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for synthesizing sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate. The method uses an alkaline eutectic solvent as both solvent and catalyst, which can conveniently prepare phosphate esters. The sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate obtained by salt formation has high yield and purity.

[0007] In one embodiment, the method for synthesizing sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate of the present invention includes:

[0008] a. 2,2′-methylene-bis(4,6-di-tert-butylphenol) was heated and dissolved in an alkaline eutectic solvent, and phosphorus oxychloride was added dropwise to carry out the reaction. Then, water and acid were added to carry out hydrolysis to obtain 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate.

[0009] b. Convert 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate to sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate.

[0010] In a preferred embodiment, the alkaline eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor comprises one or more of choline hydroxide, choline chloride, and betaine; and the hydrogen bond donor comprises one or more of methanolamine, ethanolamine, diethanolamine, triethanolamine, n-propanolamine, isopropanolamine, n-butanolamine, and n-pentanolamine.

[0011] In a preferred embodiment, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1-10:10-1, preferably 1-2:2-1, and more preferably 1:1 or 2:1.

[0012] In a preferred embodiment, the alkaline eutectic solvent includes choline chloride / ethanolamine in a molar ratio of 1:1 and choline chloride / diethanolamine in a molar ratio of 2:1.

[0013] In a preferred embodiment, the alkaline eutectic solvent is prepared by mixing hydrogen bond acceptors and hydrogen bond donors in a certain proportion, heating to 80-110°C, and stirring for a period of time.

[0014] Preferably, the stirring time can be 0.5-6 hours.

[0015] In a preferred embodiment, the molar ratio of 2,2′-methylene-bis(4,6-di-tert-butylphenol) to phosphorus oxychloride is 1:1.01-1.30, preferably 1:1.05-1.10.

[0016] In a preferred embodiment, the reaction with phosphorus oxychloride is carried out at 40-70°C, preferably at 45-60°C; the reaction time is 1-12 hours.

[0017] In a preferred embodiment, the amount of water added is not particularly limited and can be 0.2-1.0 times the mass of 2,2′-methylene-bis(4,6-di-tert-butylphenol), preferably 0.3-0.6 times.

[0018] In a preferred embodiment, the acid used for hydrolysis is one or more of hydrochloric acid, sulfuric acid, and glacial acetic acid, preferably glacial acetic acid. Only a small amount of acid needs to be added during hydrolysis; for example, the amount of glacial acetic acid used can be 1-5% of the mass of 2,2′-methylene-bis(4,6-di-tert-butylphenol).

[0019] In a preferred embodiment, step a further includes, after the reaction is complete, cooling and filtering to collect the crude 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate, followed by washing with water and drying.

[0020] In this invention, the step of converting 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate to sodium 2,2′-methylenebis(4,6-di-tert-butylphenyl) phosphate is known in the prior art. The reaction can be carried out in water or in organic solvents such as acetone, methanol, ethanol, and toluene. Preferably, carrying out the reaction in water yields the best salt-forming effect. The base used for salt formation can be one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate, with sodium hydroxide being preferred.

[0021] In a preferred embodiment, the synthesis method of the present invention further includes a process of regenerating and reusing the used alkaline eutectic solvent.

[0022] Preferably, the regeneration method of the alkaline eutectic solvent involves washing with ammonia water, drying and dehydrating at a temperature above 100°C, and then reusing it. In the synthesis method of the present invention, the alkaline eutectic solvent can be recycled multiple times.

[0023] Beneficial effects:

[0024] This invention provides a method for synthesizing sodium 2,2′-methylene bis(4,6-di-tert-butylphenyl) phosphate. Unlike existing methods that use organic solvents and acid-binding agents, this invention innovatively introduces a basic eutectic solvent into the phosphate synthesis step. This eutectic solvent not only has a good catalytic effect on the reaction of bisphenol and phosphorus oxychloride, but also exhibits low solubility in the product phosphate, making it practically insoluble at room temperature. Therefore, it can precipitate from the reaction system and promote phosphate formation. The phosphate obtained by this method can be directly used in the subsequent salt-forming reaction without purification, resulting in high yield and purity of the final product. This method is simple, easy to implement, environmentally friendly, and efficient, and is expected to be widely used in industry. Detailed Implementation

[0025] The following will describe preferred embodiments of the invention in detail. These embodiments are provided to better illustrate the invention and are not intended to limit the invention to these examples. Non-essential improvements and adjustments to the embodiments based on the invention's description still fall within the scope of the invention.

[0026] Unless otherwise specified, the experimental methods in the following embodiments are conventional methods. Where specific techniques or conditions are not specified in the embodiments, they should be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions.

[0027] Example 1:

[0028] Choline chloride and ethanolamine were fed in a 1:1 molar ratio, heated to 90°C, and maintained for 1 hour with stirring. After cooling, a eutectic solvent of choline chloride and ethanolamine was obtained.

[0029] Under nitrogen protection, 42.4 g (0.1 mol) of bisphenol (i.e., 2,2′-methylene-bis(4,6-di-tert-butylphenol)) was added to 200 ml of the solvent. The mixture was heated to 45 °C and stirred until the bisphenol was completely dissolved. Then, 16.8 g (0.11 mol) of phosphorus oxychloride was added dropwise, and the mixture was kept at 45 °C with stirring for 3 h. Subsequently, 20 ml of water and about 1 g of glacial acetic acid were added, and the mixture was hydrolyzed under vigorous stirring for 2 h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature, and the crude phosphate ester was collected by filtration. The phosphate ester was washed 2-3 times with water, dried, and used directly in the next reaction step.

[0030] The phosphate ester (2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate) obtained in the previous step was added to 200 ml of water, and NaOH solution (40% concentration, 11 g, 0.11 mol) was slowly added. The reaction was first stirred at 50 °C for 4 h, and then stirred at room temperature for 1 h. A large amount of white precipitate was precipitated. After cooling, the product was filtered to obtain the crude product. After washing with water 2-3 times, the product was recrystallized with industrial alcohol to obtain 48.2 g of pure sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate. The total yield was 94.7%, the purity was 99.1%, and the melting point was 149-150 °C.

[0031] Example 2:

[0032] Choline chloride and diethanolamine were fed in a molar ratio of 2:1, heated to 90°C, and maintained for 1 hour with stirring. After cooling, a eutectic solvent of choline chloride and diethanolamine was obtained.

[0033] Under nitrogen protection, 42.4 g (0.1 mol) of bisphenol was added to 200 ml of the solvent, heated to 55 °C, and stirred until the bisphenol was completely dissolved. Then, 16.8 g (0.11 mol) of phosphorus oxychloride was added dropwise, and the reaction was maintained at 55 °C with stirring for 2.5 h. Subsequently, 20 ml of water and about 1 g of glacial acetic acid were added, and hydrolysis was carried out under vigorous stirring for 2 h. After the reaction was completed, the mixture was allowed to cool to room temperature naturally, filtered to collect the crude phosphate ester, washed 2-3 times with water, dried, and used directly in the next reaction step.

[0034] The phosphate ester obtained in the previous step was added to 200 ml of water, and NaOH solution (40% concentration, 11 g, 0.11 mol) was slowly added. The mixture was first stirred at 50 °C for 4 h, and then stirred at room temperature for 1 h. A large amount of white precipitate was precipitated. After cooling, the mixture was filtered to obtain the crude product. After washing with water 2-3 times, the product was recrystallized with industrial alcohol to obtain 47.4 g of pure sodium 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphate. The total yield was 93.2%, the purity was 98.9%, and the melting point was 149-150 °C.

[0035] Example 3: Reuse of Eutectic Solvents

[0036] The filtered choline chloride / ethanolamine eutectic solvent from Example 1 was washed 1-2 times with ammonia water, then 1-2 times with water. It was then heated to 110°C and dried for 12 hours. After cooling, the regenerated choline chloride / ethanolamine eutectic solvent was obtained. Subsequent reaction and processing steps were performed in a similar manner to those in Example 1. The above steps were repeated multiple times. The results of obtaining the products are shown in Table 1 below:

[0037] Table 1:

[0038]

[0039] Finally, it should be noted that the above preferred 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 through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for synthesizing sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate, comprising: a. 2,2'-methylene-bis(4,6-di-tert-butylphenol) was heated and dissolved in an alkaline eutectic solvent, and phosphorus oxychloride was added dropwise to carry out the reaction. Then water and acid were added to carry out hydrolysis. After the reaction was completed, the crude product of 2,2'-methylene-bis(4,6-di-tert-butylphenyl) phosphate was collected by cooling and filtration, and then washed with water and dried. b. To convert 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate into sodium 2,2'-methylene bis(4,6-di-tert-butylphenyl) phosphate; The alkaline eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor, wherein the hydrogen bond acceptor is selected from choline chloride; the hydrogen bond donor is selected from ethanolamine and diethanolamine, and the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:1 or 2:

1.

2. The synthesis method according to claim 1, characterized in that, The alkaline eutectic solvent is selected from choline chloride / ethanolamine with a molar ratio of 1:1 and choline chloride / diethanolamine with a molar ratio of 2:

1.

3. The synthesis method according to claim 1, characterized in that, The alkaline eutectic solvent is prepared by mixing hydrogen bond acceptors and hydrogen bond donors in a certain proportion, heating to 80-110℃, and stirring for a period of time.

4. The synthesis method according to claim 1, characterized in that, The molar ratio of 2,2'-methylene-bis(4,6-di-tert-butylphenol) to phosphorus oxychloride is 1:1.01-1.

30.

5. The synthesis method according to claim 1, characterized in that, The molar ratio of 2,2'-methylene-bis(4,6-di-tert-butylphenol) to phosphorus oxychloride is 1:1.05-1.

10.

6. The synthesis method according to claim 1, characterized in that, The reaction with phosphorus oxychloride is carried out at 40-70℃ for 1-12 hours.

7. The synthesis method according to claim 6, characterized in that, The reaction with phosphorus oxychloride is carried out at 45-60℃.

8. The synthesis method according to claim 1, characterized in that, The acid used for hydrolysis is one or more of hydrochloric acid, sulfuric acid, and glacial acetic acid.

9. The synthesis method according to claim 1, characterized in that, The synthesis method also includes a process of regenerating and reusing the used alkaline eutectic solvent.

10. The synthesis method according to claim 9, characterized in that, The regeneration method of the alkaline eutectic solvent is as follows: after washing with ammonia and water, it is dried and dehydrated at a temperature above 100°C, and then reused.

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