A process for the preparation of a phosphite triester

Abstract

The application discloses a preparation method of a phosphite triester, and belongs to the field of polymer antioxidant synthesis. The method takes hydroxytyrosol and phosphorus trichloride as core raw materials, takes tetrahydrofuran as a solvent, and takes an amine or a carbonate as an acid-binding agent, and then through low-temperature dropwise adding, constant-temperature esterification and filtering and concentrating, an integrated multifunctional antioxidant phosphite triester is obtained. The product integrates six phenolic hydroxyl radical capture sites and phosphite hydroperoxide decomposition sites in a single molecule, and realizes efficient antioxidantization by relying on intramolecular cooperation. Compared with a traditional hindered phenol / phosphite compound system, the product has better compatibility, no migration and blooming, no need for ratio adjustment in processing, and a longer antioxidant induction period. The synthesis process of the application is mild, the yield is 87%-92%, the product purity is above 90%, the solvent can be recycled and reused, the application is green and low-carbon, the product can be used alone for antioxidant protection of various polymer materials, and has a good industrialization prospect.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical chemical synthesis technology, and in particular to a method for preparing a triphosphite. Background Technology

[0002] Polyolefins, rubber, coatings, lubricants and other polymer materials are highly susceptible to free radical oxidative degradation induced by heat, oxygen and light during high-temperature processing and long-term outdoor use, resulting in problems such as decreased mechanical properties, yellowing, cracking and shortened service life.

[0003] Currently, most antioxidant protection systems on the market rely on a combination of "primary antioxidant + secondary antioxidant," specifically the synergistic use of hindered phenolic antioxidants (free radical scavengers) and phosphite antioxidants (hydroperoxide decomposers). While this combination system has achieved great industrial success, it still faces the following technical bottlenecks.

[0004] 1. Poor compatibility, easy migration and blooming, and large volatilization loss: Hindered phenols and phosphites are two compounds with completely different molecular structures, and their compatibility with the polymer matrix is ​​different. When used at high temperature for a long time and stored at low temperature, the additives are easy to migrate and precipitate on the material surface (blooming). They are easy to volatilize and lose during high-temperature processing, which greatly shortens the long-term antioxidant life of the material (Reference: Chen Aiguo, Tian Jiawei. Development and application of antioxidant composite technology [J]. Modern Plastics Processing and Application, 2003, 15 (4): 34-35.).

[0005] 2. The processing ratio is difficult to control and is prone to antagonistic effects: The ratio of the two additives needs to be precisely controlled. When the ratio is unbalanced, the two will weaken each other's antioxidant effect and have an antagonistic effect. Downstream processing enterprises need to add premixing and ratio calibration processes, which increases the complexity of production and labor costs (Reference: Shi Wei, Zhang Jun. Effect of the combined use of hindered amine light stabilizer and antioxidant on the ultraviolet light stability of polymers [J]. Plastics Technology, 2010, 38 (3): 97-103.).

[0006] 3. Low intermolecular synergistic efficiency and limited antioxidant capacity: In the physical mixture system, the hindered phenol molecules and phosphite molecules are independent of each other and there is an intermolecular distance; after the phenolic hydroxyl group captures free radicals to generate ROOH, the phosphorus atoms cannot quickly decompose the hydrogen peroxide nearby, the oxidation reaction continues, the oxidation induction period of the material is short, and the antioxidant efficiency has a ceiling.

[0007] In other words, in the existing technology, the use of a compound synergistic system of hindered phenolic primary antioxidant and phosphite secondary antioxidant increases the number of unit operations. At the same time, due to uneven dispersion, there is a certain distance between the primary and secondary antioxidant molecules in the microscopic stage. When the phenolic hydroxyl group captures the free radical ROO• and becomes ROOH, ROOH cannot be rapidly decomposed into stable ROH by the phosphorus atoms in the phospholipid in time. This makes the oxidation time longer and the oxidation induction period shorter.

[0008] Tris(3,4-dihydroxyphenylethyl) phosphite is a novel antioxidant with stronger antioxidant properties than conventional combinations of hindered phenolic primary antioxidants and phosphite secondary antioxidants. Compared to traditional compound antioxidants, it significantly shortens oxidation time. This is due to its unique structure: the phenolic hydroxyl group captures the free radical ROO•, transforming it into ROOH. Because the phenolic hydroxyl group and the phosphite are in the same molecule, the ROOH is rapidly decomposed into stable ROH by the phosphorus atoms in the phosphite, exhibiting good molecular stability. Hindered phenolic and phosphite compound antioxidants are widely used in polyolefins, engineering plastics, styrene resins, synthetic rubber, polyurethane coatings, adhesives and inks, and lubricants. Therefore, this provides a certain application scenario for tris(3,4-dihydroxyphenylethyl) phosphite. Currently, a synthetic process for this molecule is not yet available on the market. Summary of the Invention

[0009] To address the shortcomings of existing hindered phenol / phosphite compound antioxidants, such as poor compatibility, cumbersome processing, and low synergistic antioxidant efficiency, this invention employs the following technical solution: a method for preparing tris(3,4-dihydroxyphenylethyl) phosphite, with the following structural formula: .

[0010] The synthetic process route for its preparation is as follows: .

[0011] The specific steps of the preparation method are as follows: S1, Raw material preparation: Hydroxytyrosol and tetrahydrofuran are fed at a ratio of 1:2-4v / m, phosphorus trichloride 0.3-0.7 equivalents and acid-binding agent 1-1.5 equivalents are added.

[0012] S2. Reaction process: Add tetrahydrofuran to the reaction flask, then add hydroxytyrosol and stir. Add an acid-binding agent at room temperature, then slowly add phosphorus trichloride dropwise to the reaction flask for 1-2 hours. Slowly raise the temperature to 50-80℃ and react for 1-3 hours under stirring.

[0013] S3. Post-processing: After the reaction is complete, restore to room temperature, filter, and concentrate under reduced pressure to produce a pale yellow product.

[0014] First, the integrated antioxidant in this solution achieves a synergistic effect within the molecule. When the phenolic hydroxyl group in the molecule captures free radicals (ROO•) and converts them into hydroperoxides (ROOH), the phosphorus atoms within the same molecule can rapidly decompose them into stable alcohols (ROH). This seamless "capture-decomposition" process within the same molecule greatly shortens the oxidation reaction time, resulting in significantly better antioxidant efficiency than conventional compound products.

[0015] Secondly, the antioxidant in this solution integrates the hindered phenolic structure and the phosphite structure into the same molecule, fundamentally eliminating the compatibility problem between the two additives and greatly improving its long-term stability in the material.

[0016] Furthermore, the integrated antioxidant in this solution possesses both primary and secondary antioxidant functions, eliminating the need for complex compounding ratio adjustments. It can be added directly as a single component to exert its high-efficiency effect, greatly simplifying the processing technology for downstream users.

[0017] Preferably, the acid-binding agent is selected from any one of triethylamine, ethylenediamine, DBU, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

[0018] Preferably, the reaction conditions are: hydroxytyrosol: phosphorus trichloride: triethylamine: tetrahydrofuran = 1:0.4:1.1:2 v / m (equivalent / volume mass).

[0019] Preferably, the esterification reaction temperature is 65±5℃ and the reaction time is 2 hours.

[0020] Preferably, in the raw material preparation step: hydroxytyrosol and tetrahydrofuran are fed at a feeding ratio of 1:2v / m, phosphorus trichloride is added at 0.4 equivalents, and triethylamine is added at 1.1 equivalents.

[0021] Preferably, in the reaction process steps: tetrahydrofuran is added to the reaction flask, then hydroxytyrosol is added and stirred, triethylamine is added at room temperature, then phosphorus trichloride is slowly added dropwise to the reaction flask for 1-2 hours, the temperature is slowly raised to 65±5℃, and the reaction is carried out for 2 hours under stirring.

[0022] The triphosphite product obtained by this method has a high yield and purity.

[0023] Preferably, the post-processing steps are as follows: the reaction solution is cooled to room temperature and then filtered; the filter cake is washed with tetrahydrofuran; all organic filtrates are combined; tetrahydrofuran is removed by vacuum distillation to obtain a pale yellow triphosphite product.

[0024] More preferably, the single molecule contains three 3,4-dihydroxyphenylethyl units, a total of six phenolic hydroxyl groups and one phosphite group.

[0025] The specific molecular structure of tris(3,4-dihydroxyphenylethyl) phosphite contains six phenolic hydroxyl groups and one phosphite group in one molecule, achieving synergistic intramolecular antioxidant function.

[0026] The beneficial effects of this invention are: 1. Stronger antioxidant performance and longer oxidation induction period, that is, it provides a novel antioxidant containing hindered phenol and phosphorus. This antioxidant is not a simple functional group superposition, but achieves excellent antioxidant effect through the division of labor and cooperation of functional groups. The tris(3,4-dihydroxyphenylethyl) phosphite has a novel molecular structure, with a single molecule containing 6 phenolic hydroxyl groups and 1 phosphite group, achieving intramolecular antioxidant synergy.

[0027] 2. Excellent compatibility, solving migration and blooming problems. The antioxidant integrates the hindered phenolic structure and the phosphite structure into the same molecule, fundamentally eliminating the compatibility problem between the two additives, greatly improving its long-term stability in the material, increasing the molecular weight of the antioxidant, and thus improving its volatility resistance, oil resistance, high temperature resistance and other properties.

[0028] 3. Simplified processing and reduced application complexity: The integrated antioxidant itself has both primary and secondary antioxidant functions, eliminating the need for complex compounding ratio adjustments. It can be added directly as a single component to exert a highly efficient effect, greatly simplifying the processing technology of downstream users. It responds to the concept of carbon neutrality and green development, and improves the utilization rate of antioxidant molecules through molecular design, thereby reducing resource consumption. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0030] The technical solutions of the various embodiments can be combined with each other, but must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this invention. Example 1

[0031]

[0032] Add 200 ml of tetrahydrofuran, 1-1.5 equivalents of sodium carbonate (1.2 equivalents in this example), and 100 g of hydroxytyrosol to the reaction flask and start stirring. Add 27 g of phosphorus trichloride to the constant pressure dropping funnel and slowly add it dropwise to the reaction flask over 1-2 hours. After the addition is complete, raise the temperature to 65±5℃ and stir for 2 hours. After the reaction is complete, return to room temperature, filter, wash the filter cake with tetrahydrofuran, combine the organic phases, and concentrate the organic phase under reduced pressure to obtain 83.89 g of a pale yellow product, with a yield of 87% and a purity of 95%. Example 2

[0033]

[0034] Add 150 ml of tetrahydrofuran, 1.2 equivalents of base (the base can be sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, triethylamine, ethylenediamine, or DBU; triethylamine is used in this example), and 74 g of hydroxytyrosol to the reaction flask. Start stirring. Add 20 g of phosphorus trichloride to a constant pressure dropping funnel and slowly add it dropwise to the reaction flask over 1-2 hours. After the addition is complete, raise the temperature to 65 ± 5 °C and stir for 2 hours. After the reaction is complete, allow it to return to room temperature, filter, wash the filter cake with tetrahydrofuran, combine the organic phases, and concentrate the organic phase under reduced pressure to obtain 65.71 g of a pale yellow product, with a yield of 92% and a purity of 96%. Example 3

[0035]

[0036] Add 135 ml of tetrahydrofuran, 48.63 g of triethylamine, and 67.36 g of hydroxytyrosol to the reaction flask and start stirring. Add 20 g of phosphorus trichloride to a constant pressure dropping funnel and slowly add it dropwise to the reaction flask over 1 hour. After the addition is complete, raise the temperature to 65 ± 5 °C and stir for 2 hours. After the reaction is complete, allow it to return to room temperature, filter, wash the filter cake with tetrahydrofuran, combine the organic phases, and concentrate the organic phase under reduced pressure to obtain 63.57 g of a pale yellow product, with a yield of 89% and a purity of 94%. Example 4

[0037]

[0038] Add 200 ml of tetrahydrofuran, 118.15 g of triethylamine, and 50 g of hydroxytyrosol to the reaction flask and start stirring. Add 26.72 g of phosphorus trichloride to the constant pressure dropping funnel and slowly add it dropwise to the reaction flask over 2 hours. After the addition is complete, raise the temperature to 65 ± 5 °C and stir for 2 hours. After the reaction is complete, return to room temperature, filter, wash the filter cake with tetrahydrofuran, combine the organic phases, and concentrate the organic phase under reduced pressure to obtain 124 g of yellow product, with a yield of 78% and a purity of 90%.

[0039] As can be seen from the above embodiments, this invention uses hydroxytyrosol and phosphorus trichloride as core raw materials, tetrahydrofuran as solvent, and amines or carbonates as acid-binding agents. Through low-temperature dropwise addition, isothermal esterification, filtration, and concentration, an integrated multifunctional antioxidant, tris(3,4-dihydroxyphenylethyl) phosphite, is obtained. This product integrates six phenolic hydroxyl radical capturing sites and phosphite hydroperoxide decomposition sites in a single molecule, achieving highly efficient antioxidant effects through intramolecular synergy. Compared with traditional hindered phenol / phosphite complex systems, it exhibits better compatibility, no migration or blooming, requires no ratio adjustment during processing, and has a longer antioxidant induction period. The synthesis process of this invention is mild, with a yield of 87%-92% and a product purity of over 90%. The solvent is recyclable and reusable, making it green and low-carbon. It can be used alone for antioxidant protection of various polymer materials and has good industrialization prospects.

[0040] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the invention. Furthermore, it should be understood that after reading the technical description of this invention, those skilled in the art can make various alterations, modifications, and / or variations to the invention, and all such equivalent forms also fall within the scope of protection defined by the appended claims.

Claims

1. A method for preparing a triphosphite, characterized in that: The structure is as follows: ; The synthetic process route for its preparation is as follows: ; The specific steps of the preparation method are as follows: S1. Raw material preparation: Hydroxytyrosol and tetrahydrofuran are fed at a ratio of 1:2-4v / m, phosphorus trichloride is added at 0.3-0.7 equivalents, and acid-binding agent is added at 1-1.5 equivalents; S2. Reaction process: Add tetrahydrofuran to the reaction flask, then add hydroxytyrosol and stir. Add an acid-binding agent at room temperature, then slowly add phosphorus trichloride dropwise to the reaction flask for 1-2 hours. Slowly raise the temperature to 50-80℃ and react for 1-3 hours under stirring. S3. Post-processing: After the reaction is complete, restore to room temperature, filter, and concentrate under reduced pressure to produce a pale yellow product.

2. The method for preparing a triphosphite according to claim 1, characterized in that: The acid-binding agent is selected from any one of triethylamine, ethylenediamine, DBU, sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

3. The method for preparing a triphosphite according to claim 2, characterized in that: Reaction conditions: Hydroxytyrosol: Phosphorus trichloride: Triethylamine: Tetrahydrofuran = 1:0.4:1.1:2 v / m.

4. The method for preparing a triphosphite according to claim 2, characterized in that: The esterification reaction temperature was 65±5℃, and the reaction time was 2 hours.

5. The method for preparing a triphosphite according to claim 2, characterized in that: In the raw material preparation steps: hydroxytyrosol and tetrahydrofuran are fed at a ratio of 1:2v / m, phosphorus trichloride is added at 0.4 equivalents, and triethylamine is added at 1.1 equivalents.

6. The method for preparing a triphosphite according to claim 2, characterized in that: In the reaction process: tetrahydrofuran is added to the reaction flask, then hydroxytyrosol is added and stirred, triethylamine is added at room temperature, and then phosphorus trichloride is slowly added dropwise to the reaction flask for 1-2 hours. The temperature is slowly raised to 65±5℃ and the reaction is carried out for 2 hours under stirring.

7. The method for preparing a triphosphite according to claim 2, characterized in that: The post-processing steps are as follows: after cooling the reaction solution to room temperature, filter it, wash the filter cake with tetrahydrofuran, combine all the organic filtrates, remove tetrahydrofuran by vacuum distillation, and obtain the pale yellow triphosphite product.

8. The triphosphite prepared according to any one of claims 1-7, characterized in that, The single molecule contains three 3,4-dihydroxyphenylethyl units, a total of six phenolic hydroxyl groups and one phosphite group.

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