Preparation method of tris (2, 4-di-tert-butylphenyl) phosphite

Abstract

The invention relates to the field of chemical synthesis, and provides a preparation method of tris (2, 4-di-tert-butylphenyl) phosphite, which comprises the following steps: (1) dispersing 2, 4-di-tert-butylphenol and a catalyst in a solvent I, heating to 30-50 DEG C, and adding phosphorus trichloride for vacuum reaction; the catalyst is tetramethyl guanidine acid radical ionic liquid; (2) heating to 100-140 DEG C, and reacting to obtain a crude product; or heating to 100-140 DEG C, reacting to obtain a crude product, crystallizing and purifying the crude product to obtain a pure product and crystallization mother liquor, and recovering the catalyst from the crystallization mother liquor. According to the method disclosed by the invention, the tris (2, 4-di-tert-butylphenyl) phosphite ester with high yield and high purity is prepared under mild conditions by taking the tetramethyl guanidine acid radical ionic liquid as a catalyst, and the catalyst is easy to recover and can be used for multiple times.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, in particular to a method for preparing tris(2,4-di-tert-butylphenyl)phosphite. Background Art

[0002] Tris(2,4-di-tert-butylphenyl)phosphite (hereinafter referred to as antioxidant 168), molecular formula C 42 H 62 O3P. Antioxidant 168 is one of the commonly used phosphite auxiliary antioxidants in the world. It has the special functions of high temperature resistance, hydrolysis resistance, no discoloration and no coloring. It is widely used in the antioxidant effect of polyethylene, polypropylene, polystyrene, polyvinyl chloride, ABS and various fiber resins.

[0003] The mainstream preparation method of antioxidant 168 is: using 2,4-di-tert-butylphenol and phosphorus trichloride as raw materials, and obtaining it through esterification reaction under the action of a catalyst. The reaction formula is as follows: Among them, the selection of catalyst is one of the core processes of the synthesis process of antioxidant 168. Existing synthesis process catalysts generally use nitrogen-containing alkaline organic compounds, such as triethylamine, pyridine, N,N-dimethylformamide, di-n-butylamine, etc. For example, patent CN109593101A discloses a method for preparing a phosphite antioxidant 168, in which phosphorus trichloride is added dropwise to 2,4-di-tert-butylphenol and a catalyst mixture to prepare antioxidant 168, and the catalyst is di-n-butylamine. Although such catalysts can effectively catalyze the synthesis reaction of antioxidant 168, they have the disadvantages of strong irritation and heavy odor. Moreover, this type of reaction system belongs to a homogeneous reaction system, and the separation of the catalyst and the product is relatively difficult, and the recycling economy is poor. Therefore, an ideal solution is needed. Summary of the invention

[0004] The invention provides a method for preparing tris(2,4-di-tert-butylphenyl)phosphite. With tetramethylguanidine ionic liquid as a catalyst, high-yield and high-purity tris(2,4-di-tert-butylphenyl)phosphite is prepared under mild conditions. The catalyst is easy to recover and can be used multiple times.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) dispersing 2,4-di-tert-butylphenol and a catalyst in a solvent I, heating to 30-50° C., adding phosphorus trichloride and reacting in vacuum; the catalyst is a tetramethylguanidine ionic liquid; (2) heating to 100-140° C. to react and obtain a crude tris(2,4-di-tert-butylphenyl)phosphite; or, heating to 100-140° C. to react and obtain a crude tris(2,4-di-tert-butylphenyl)phosphite, the crude product is purified by crystallization to obtain a pure product and a crystallization mother liquor, and the catalyst is recovered from the crystallization mother liquor. Preferably, the catalyst is a tetramethylguanidine tryptophan ionic liquid or a tetramethylguanidine proline ionic liquid, and more preferably a tetramethylguanidine tryptophan ionic liquid.

[0006] Preferably, the mass of the catalyst is 5-10% of the mass of phosphorus trichloride. Too much catalyst will lead to difficulty in post-reaction treatment; too little catalyst will lead to slow reaction rate and incomplete reaction.

[0007] Preferably, solvent I is toluene or xylene.

[0008] Preferably, the reaction time of step (1) is 1-3 h.

[0009] Preferably, the molar ratio of phosphorus trichloride to 2,4-di-tert-butylphenol is 1:3.0-3.1. The amount of raw material 2,4-di-tert-butylphenol should be moderate. If the amount is too large, it will be difficult to handle; if the amount is too small, the reaction rate will be slow and the phosphorus trichloride reaction will not be complete.

[0010] The vacuum pressure in step (1) is 85-95 kPa. The vacuum negative pressure can remove the generated HCl in time to promote the forward reaction, but too high a negative pressure will cause the solvent and phosphorus trichloride to be drawn away.

[0011] Preferably, the reaction temperature in step (2) is 100-130°C.

[0012] Preferably, the reaction time of step (2) is 2-3 h.

[0013] Step ② After the reaction, the crude product of tris(2,4-di-tert-butylphenyl)phosphite is obtained by vacuum distillation. The solvent I and unreacted phosphorus trichloride are removed by vacuum distillation.

[0014] Preferably, the crystallization process is: adding the crude tri(2,4-di-tert-butylphenyl)phosphite to solvent II, heating to dissolve, cooling to crystallize, filtering to obtain a crystallization mother liquor and a solid, and drying the solid to obtain a pure product; solvent II is an alcohol solvent, and the alcohol solvent is further preferably one of methanol, ethanol, and isopropanol.

[0015] Preferably, the process of recovering the catalyst from the crystallization mother liquor is: removing the solvent II in the crystallization mother liquor to obtain a residue, dissolving the residue with a solvent III, filtering the filtrate, removing the solvent III in the filtrate, and obtaining the catalyst; the solvent III is water.

[0016] Therefore, the beneficial effects of the present invention are as follows: (1) The combination of tetramethylguanidine and amino acid ions achieves a good catalytic effect, and tris(2,4-di-tert-butylphenyl)phosphite with high yield and high purity is obtained under mild conditions. Tetramethylguanidine has strong alkalinity and small molecular volume, and has small steric hindrance when combined with amino acid anions containing a ring structure; amino acid ionic liquids have stronger polarity due to the larger hydrogen bonding effect within their molecules, which is beneficial to the catalytic reaction. (2) Tetramethylguanidine has good symmetry and strong inter-ionic interaction, which can promote the separation of products and the recovery of catalysts. After the reaction is completed, the catalyst and product can be separated by adding a solvent, and the catalyst can be reused without the generation of solid waste. (3) The catalyst still exhibits good catalytic activity after being recycled 5 times. (4) The preparation process of the present invention is simple and has good economic benefits. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further described below through specific embodiments.

[0018] In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art. Unless otherwise specified, parts are all weight parts, temperatures are expressed in ° C or at ambient temperature, and pressures are atmospheric pressure or near atmospheric pressure. There are many variations and combinations of reaction conditions (such as component concentrations, desired solvents, solvent mixtures, temperatures, pressures, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the product obtained by the method, and only reasonable routine experiments will be required to optimize such method conditions.

[0019] Example The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol and the catalyst tetramethylguanidine ion liquid are added to solvent I (preferably toluene or xylene), stirred to make them uniformly dispersed, heated to 30-50°C, phosphorus trichloride is added dropwise to the system, the system pressure is controlled to be 80-95kPa, and the reaction is stirred for 1.0-3.0h; the decompression during the reaction is to remove the HCl gas generated by the reaction in time. The molar ratio of phosphorus trichloride to 2,4-di-tert-butylphenol is 1:3.0-3.1, and the mass of the catalyst is 5-10% of the mass of phosphorus trichloride. The catalyst is (a) tetramethylguanidine tryptophan ion liquid or (b) tetramethylguanidine proline ion liquid, and the molecular formula is as follows: (a) (b)

[0020] (2) The temperature is then raised to 100-140° C. (more preferably 100-130° C.) and the reaction is continued with stirring for 2.0-3.0 hours. After the reaction is completed, the solvent I and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0021] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II (preferably an alcohol solvent), heat and stir to fully dissolve the crude product, then cool naturally to crystallize, and filter to obtain a solid and a crystallization mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, and the product color is white. After the crystallization mother liquor is distilled under reduced pressure to recover solvent II, a viscous liquid is obtained. Solvent III (preferably water) is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 0.5-1.5 hours and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid, and the amount of ionic liquid recovered is determined by weighing.

[0022] Example 1 The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0023] (2) The temperature was raised to 120° C. and the reaction was continued with stirring for 2.0 h. After the reaction was completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride were removed under reduced pressure, and the solid was precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite, with an HPLC yield of 98.8%.

[0024] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II isopropanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, and filter to obtain solid and crystal mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity. The product color is white and the crystal purity is 99.7%. The crystal mother liquor is subjected to reduced pressure distillation to recover solvent II isopropanol to obtain a viscous liquid. 20 mL of solvent III water is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 1.0 h and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid. The amount of ionic liquid recovered is determined by weighing.

[0025] The recovered catalyst tetramethylguanidine tryptophan ionic liquid was recycled and the operations of steps (1) to (3) were repeated. After recycling for 5 times, the HPLC yield of tris(2,4-di-tert-butylphenyl)phosphite could reach 97.9%. The specific recycling yields are shown in Table 1.

[0026] Table 1. Use times Catalyst tetramethylguanidine tryptophan ionic liquid recovery weight (g) Yield of tris(2,4-di-tert-butylphenyl)phosphite (%) 1 1.55(initial weight) 98.8 2 1.52 98.5 3 1.52 98.4 4 1.50 98.4 5 1.48 97.9 Example 2 The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (92.8 g, 0.45 mol, 3.0 eq) and 1.03 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I toluene, stirred to make them uniformly dispersed, heated to 30°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 3.0 h.

[0027] (2) The temperature was raised to 100° C. and the reaction was continued with stirring for 3.0 h. After the reaction was completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride were removed under reduced pressure, and the solid was precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite, with an HPLC yield of 97.1%.

[0028] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II methanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, filter to obtain solid and crystal mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, the product color is white, and the crystal purity is 99.0%. After the crystal mother liquor is recovered by vacuum distillation of solvent II isopropanol, a viscous liquid is obtained. 20mL of solvent III water is added to the viscous liquid and stirred to disperse, solid is precipitated (the solid is mainly 2,4-di-tert-butylphenol), continue stirring for 1.0h and filter, the filtrate can be spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid.

[0029] Example 3 The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (95.9 g, 0.465 mol, 3.1 eq) and 2.06 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make them uniformly dispersed, heated to 50°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 1.0 h.

[0030] (2) The temperature was raised to 130° C. and the reaction was continued with stirring for 2.0 h. After the reaction was completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride were removed under reduced pressure, and the solid was precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite, with an HPLC yield of 98.0%.

[0031] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II ethanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, filter to obtain solid and crystal mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, the product color is white, and the crystal purity is 99.5%. After the crystal mother liquor is recovered by vacuum distillation of solvent II isopropanol, a viscous liquid is obtained. 20mL of solvent III water is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 1.0h and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid.

[0032] Example 4 The difference from Example 1 is that the reaction temperature in the second stage is 140° C. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0033] (2) The temperature is then raised to 140° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0034] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II ethanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, and filter to obtain solid and crystallization mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, and the product color is white. After the crystallization mother liquor is distilled under reduced pressure to recover solvent II isopropanol, a viscous liquid is obtained. 20mL of solvent III water is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 1.0h and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid.

[0035] Example 5 The difference from Example 1 is that the amount of catalyst used is relatively large. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 2.47 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make them uniformly dispersed, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0036] (2) The temperature is then raised to 120° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0037] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II ethanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, and filter to obtain solid and crystallization mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, and the product color is white. After the crystallization mother liquor is distilled under reduced pressure to recover solvent II isopropanol, a viscous liquid is obtained. 20mL of solvent III water is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 1.0h and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid.

[0038] Example 6 The difference from Example 1 is that the ionic liquid catalyst is a tetramethylguanidine proline ionic liquid. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine proline ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0039] (2) The temperature is then raised to 120° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0040] (3) Add the crude tris(2,4-di-tert-butylphenyl)phosphite to solvent II ethanol, heat and stir to fully dissolve the crude product, then cool naturally to crystallize, and filter to obtain solid and crystallization mother liquor. The solid can be dried to obtain tris(2,4-di-tert-butylphenyl)phosphite of high purity, and the product color is white. After the crystallization mother liquor is distilled under reduced pressure to recover solvent II isopropanol, a viscous liquid is obtained. 20mL of solvent III water is added to the viscous liquid and stirred to disperse. Solids are precipitated (the solids are mainly 2,4-di-tert-butylphenol). Stirring is continued for 1.0h and then filtered. The filtrate is spin-dried to recover the catalyst tetramethylguanidine tryptophan ionic liquid.

[0041] Comparative Example Comparative Example 1 The difference from Example 1 is that there is no heating reaction in the first stage. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to disperse evenly, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to be 80-95 kPa, the temperature was directly raised to 120 ° C and stirred for reaction for 4.0 h, after the reaction was completed, the solvent I anhydrous xylene and unreacted phosphorus trichloride were removed under reduced pressure, and the solid was precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl) phosphite.

[0042] Comparative Example 2 The difference from Example 1 is that the reaction is carried out under normal pressure. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine tryptophan ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, and the reaction was stirred at normal pressure for 4.0 h.

[0043] (2) The temperature is then raised to 120° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0044] Comparative Example 3 The difference from Example 1 is that the anion of the ionic liquid catalyst is different, that is, tetramethylguanidine formate. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst tetramethylguanidine carboxylate were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0045] (2) The temperature is then raised to 120° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0046] Comparative Example 4 The difference from Example 1 is that the cation of the ionic liquid catalyst is different, which is 1-butyl-3-methylimidazolium tryptophanate ionic liquid. The details are as follows: The preparation method of tris(2,4-di-tert-butylphenyl)phosphite comprises the following steps: (1) Under nitrogen protection, 2,4-di-tert-butylphenol (94.4 g, 0.457 mol, 3.05 eq) and 1.55 g of catalyst 1-butyl-3-methylimidazolium tryptophanate ionic liquid were added to 100 mL of solvent I anhydrous xylene, stirred to make the dispersion uniform, heated to 40°C, phosphorus trichloride (20.6 g, 0.15 mol, 1.0 eq) was added dropwise to the system, the system pressure was controlled to 80-95 kPa, and the reaction was stirred for 2.0 h.

[0047] (2) The temperature is then raised to 120° C. and the reaction is continued with stirring for 2.0 h. After the reaction is completed, the solvent I, anhydrous xylene and unreacted phosphorus trichloride are removed under reduced pressure, and the solid is precipitated by cooling to obtain a crude product of tri(2,4-di-tert-butylphenyl)phosphite.

[0048] Performance Testing The crude yield and crystal purity of tris(2,4-di-tert-butylphenyl)phosphite of each embodiment and comparative example are summarized as shown in Table 2.

[0049] Table 2. As can be seen from the above table, the present invention uses tetramethylguanidine tryptophan root ionic liquid as a catalyst, and the obtained tris (2,4-di-tert-butylphenyl) phosphite has a high yield. Comparative Example 3 uses tetramethylguanidine formate as a catalyst, which is different from the anion of the catalyst in Example 1. Comparative Example 4 uses 1-butyl-3-methylimidazole tryptophan root ionic liquid, which is different from the cation of the catalyst in Example 1. The catalytic effect is not as good as Example 1, indicating that tetramethylguanidine and amino acid ions can achieve the best effect. The reasons are analyzed as follows ① cation: Compared with 1-butyl-3-methylimidazole, tetramethylguanidine has a stronger alkalinity and is more conducive to promoting the reaction. In view of the fact that the anion of the present invention is an amino acid anion, containing a cyclic structure, with tetramethylguanidine, the steric hindrance of the ionic liquid molecule is smaller, which is conducive to catalysis, and 1-butyl-3-methylimidazole itself also contains a cyclic structure, and the molecular steric hindrance is large. In addition, the symmetry of tetramethylguanidine is better, the interaction between ions is stronger, the viscosity is greater, and the intermittent miscibility between the product and the ionic liquid is larger, which can promote the separation of the product and the recovery of the catalyst. Therefore, after the catalyst of comparative example 4 is used continuously for 5 times, only 1.03g can be recovered, which is lower than 1.48g of example 1. ② Anions: Compared with conventional ionic liquids, amino acid ionic liquids have stronger polarity due to the larger hydrogen bonding effect in their molecules, which is conducive to catalytic reactions. Among the amino acid ionic liquids, Example 7 is pyrrole-containing proline, and Example 1 is indole-containing tryptophan. Indole has a bicyclic structure consisting of a benzene ring and a nitrogen-containing pyrrole ring. The nitrogen atom provides a pair of lone pairs of electrons to form a conjugated system, thereby stabilizing the indole structure. This conjugation effect makes the indole compound weakly alkaline, and an electrophilic substitution reaction can occur at the 3-position of its pyrrole ring. In contrast, the lone pair of electrons on the nitrogen atom in pyrrole participates in the conjugated system of the ring, which reduces the electron cloud density of the nitrogen atom, resulting in weaker alkalinity of pyrrole, and its conjugation effect is not as strong as indole, so the catalytic effect of tryptophan is worse than that of proline.

[0050] Analysis of the effect of experimental parameters on yield: Comparative Example 1 does not have the first stage heating reaction. Direct heating to 120°C will cause fuming, which poses a safety hazard. Moreover, due to fuming, phosphorus trichloride will be drawn away, resulting in a decrease in product yield. Comparative Example 2 The reaction is carried out under normal pressure, which is not conducive to the timely removal of the generated HCl, resulting in a prolonged reaction time and a decrease in product yield. Example 4 The second stage reaction temperature is higher, which leads to an increase in side reactions and a decrease in product yield. Example 5 The amount of catalyst used is increased, but the product yield decreases instead. This is because of the particularity of the ionic liquid catalyst. It may be that the concentration change affects the viscosity and other properties of the ionic liquid catalyst, changing the catalytic process.

[0051] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing tris(2,4-di-tert-butylphenyl)phosphite, characterized in that: The following steps are involved: (1) Dispersing 2,4-di-tert-butylphenol and a catalyst in solvent I, heating to 30-50°C, adding phosphorus trichloride and reacting in vacuum; the catalyst is a tetramethylguanidine ionic liquid; (2) Raising the temperature to 100-140°C to react and obtain a crude product of tris(2,4-di-tert-butylphenyl)phosphite; or, raising the temperature to 100-140°C to react and obtain a crude product of tris(2,4-di-tert-butylphenyl)phosphite, and purifying the crude product by crystallization to obtain a pure product and a crystallization mother liquor, and recovering the catalyst from the crystallization mother liquor.

2. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: The catalyst is a tetramethylguanidine tryptophan ionic liquid or a tetramethylguanidine proline ionic liquid.

3. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1 or 2, characterized in that: The mass of the catalyst is 5-10% of the mass of phosphorus trichloride.

4. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: Solvent I is toluene or xylene.

5. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: The reaction time of step (1) is 1-3 h.

6. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: The molar ratio of phosphorus trichloride to 2,4-di-tert-butylphenol is 1:3.0-3.

1.

7. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, 5 or 6, characterized in that: Step (1) The vacuum pressure is 85~95 kPa.

8. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: The reaction time of step (2) is 2-3 h.

9. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1, characterized in that: The crystallization process is as follows: adding crude tri(2,4-di-tert-butylphenyl)phosphite into solvent II, heating to dissolve, cooling to crystallize, filtering to obtain a crystallization mother liquor and a solid, and drying the solid to obtain a pure product.

10. The method for preparing tris(2,4-di-tert-butylphenyl)phosphite according to claim 1 or 9, characterized in that: The process of recovering the catalyst from the crystallization mother liquor is as follows: removing the solvent II in the crystallization mother liquor to obtain a residue, dissolving the residue with the solvent III, filtering the filtrate, removing the solvent III in the filtrate, and obtaining the catalyst.

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