Preparation method of bidentate phosphite

Abstract

The invention relates to the field of ligand preparation, and discloses a preparation method of bidentate phosphite. The preparation method comprises the following steps: (1) mixing 2, 2 '-diphenol, phosphorus trichloride and a solvent I, and carrying out a first reaction to obtain a first reaction solution; (2) adding the first reaction liquid and bisphenol 2, 2-dihydroxybenzene into a reaction kettle; 2, 2 '-dihydroxy-4, 4', 6, 6 '-tetra-tert-butyl-1, 1'-biphenyl, an acid-binding agent, an auxiliary agent and a solvent II are mixed and subjected to a second reaction, and bidentate phosphite shown in the formula (1) is obtained. The preparation method provided by the invention is high in product yield and purity, low in content of impurities such as chloride ions and iron ions and short in reaction period, product purification does not need recrystallization, and the method is suitable for industrial production. The method is more suitable for amplified preparation.

Description

Technical Field

[0001] The present invention relates to the field of ligand preparation, and in particular to a method for preparing a bidentate phosphite. Background Art

[0002] Rhodium-phosphine complex catalysts are widely used in olefin hydroformylation reactions, demonstrating high catalytic performance and playing a crucial role in the reaction. In rhodium-phosphine complex catalyst systems, ligand research has long been a focus and hot topic in the scientific community, as the ligand can significantly influence catalytic activity and selectivity.

[0003] At present, bidentate phosphite ligands are widely used in the field of transition metal-catalyzed organic chemistry, such as olefin hydroformylation and hydroesterification reactions. In the hydroformylation reaction of internal olefins, the rhodium / bidentate phosphite catalytic system shows good reaction effect.

[0004] In the synthesis method of bidentate phosphite disclosed in CN1986055B, an excess of phosphorus trichloride is first reacted with diphenol to obtain a phosphine-chloride intermediate product, and then a mixed solution of substituted diphenol and triethylamine is slowly added dropwise to the phosphine-chloride reaction system. After the reaction is completed, the bidentate phosphite product is filtered, concentrated, and recrystallized.

[0005] The one-pot two-step method for synthesizing bidentate phosphites disclosed in CN108129515A also comprises the steps of dropwise adding phosphorus trichloride to an organic solution containing biphenol, an organic base and a catalyst, adding a mixed solution containing a substituted biphenol to the reaction solution after the reaction is completed, cooling the reaction solution to room temperature, filtering, concentrating and recrystallizing the product.

[0006] In the above method, all is to first adopt excessive phosphorus trichloride and biphenol to react and generate phosphorus chlorine intermediate, then react with other bisphenols, obtain bisphosphite product after recrystallization reaction.But in the preparation process of such compounds, organic raw material contains a large amount of chloride ions, yet in carbonyl synthesis production equipment, reaction requires extremely high purity and impurity content of organophosphine ligand, because chloride ion content is too high and can affect the catalytic activity of carbonyl synthesis reaction, also can accelerate corrosion reaction kettle body simultaneously, therefore chloride ion content is the important index of evaluation part in the part of preparation. Iron ion is owing to can form coordination compound with carbonyl in carbonyl synthesis reaction, affects the catalytic activity of rhodium catalyst, therefore in iron ion (Fe 3+ ) content also has strict requirements.

[0007] In actual operation, the filtration, concentration and recrystallization reaction cycle is long. It is difficult to purify the product without multiple recrystallizations. The existing bidentate phosphite preparation process has a low yield and is difficult to purify, which easily causes environmental and economic pressures. Therefore, it is necessary to improve the existing process and develop a process with high product purity and yield, low content of impurities such as chloride ions and iron ions, and no need for recrystallization for product purification, which is suitable for scale-up. Summary of the Invention

[0008] The purpose of the present invention is to overcome the problems of the prior art in that the filtration, concentration and recrystallization reaction cycles are long, the product is difficult to purify without recrystallization, and it is not suitable for scale-up preparation. A method for preparing a bidentate phosphite is provided. The preparation method has the advantages of high product purity and yield, low content of impurities such as chloride ions and iron ions, and no need for recrystallization to purify the product, which is suitable for scale-up.

[0009] In order to achieve the above object, the present invention provides a method for preparing a bidentate phosphite, which comprises the following steps:

[0010] (1) mixing 2,2'-biphenol, phosphorus trichloride and solvent I to perform a first reaction to obtain a first reaction solution;

[0011] (2) mixing the first reaction solution, bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl, an acid-binding agent, an auxiliary agent and a solvent II to carry out a second reaction to obtain a bidentate phosphite represented by formula (1).

[0012]

[0013] Through the above technical solution, the beneficial effects of the present invention are:

[0014] The preparation method of the present invention is simple to operate, does not require recrystallization for product purification, and the obtained bidentate phosphite product has high purity and low content of impurities such as chloride ions and iron ions. It also improves preparation efficiency, reduces costs, reduces the amount of reagents used, alleviates environmental pressure, and is suitable for industrial batch preparation.

[0015] In a preferred embodiment of the present invention, by selecting an appropriate molar ratio of phosphorus trichloride, 2,2'-biphenol, and bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl, reaction conditions, the types and amounts of acid-binding agents and auxiliary agents, and separation process conditions, the purity and yield of the bidentate phosphite product are further improved, and the content of impurities such as chloride ions and iron ions is further reduced. Under the preferred conditions, the resulting bidentate phosphite product has a purity of over 99 wt% and a yield of over 70%. The chloride ion content per kg of the bidentate phosphite product is less than 3 mg, and the iron ion content is less than 2 mg. DETAILED DESCRIPTION

[0016] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0017] The present invention provides a method for preparing a bidentate phosphite, wherein the preparation method comprises the following steps:

[0018] (1) mixing 2,2'-biphenol, phosphorus trichloride and solvent I to perform a first reaction to obtain a first reaction solution;

[0019] (2) mixing the first reaction solution, bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl, an acid-binding agent, an auxiliary agent and a solvent II to carry out a second reaction to obtain a bidentate phosphite represented by formula (1).

[0020]

[0021] According to the present invention, preferably, in step (1), phosphorus trichloride and 2,2'-biphenol are mixed in a molar ratio of (1.5-3):1.

[0022] In order to fully dissolve phosphorus trichloride and 2,2'-biphenol in solvent I, preferably, 2,2'-biphenol and solvent I are first mixed at room temperature, and then the mixture is mixed with phosphorus trichloride at 35-45°C.

[0023] According to the present invention, preferably, the amount of the solvent I added is 1.3-3.5 mL relative to 1 g of 2,2'-biphenol.

[0024] In order to further promote the smooth progress of the first reaction, preferably, the water content of the solvent I is not higher than 1000 mg / L.

[0025] According to the present invention, preferably, the solvent I is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran and 1,4-dioxane.

[0026] According to the present invention, preferably, the temperature of the first reaction is 60-70° C., and the time is 1-2.5 h.

[0027] According to the present invention, preferably, the first reaction is carried out in the presence of a protective gas, which may be an inert gas and / or nitrogen. Preferably, the protective gas is nitrogen.

[0028] According to the present invention, preferably, step (1) further comprises: removing excess phosphorus trichloride and solvent I from the product obtained by the first reaction. The present invention is not particularly limited to the method for removing excess phosphorus trichloride and solvent I. For example, the product after the first reaction can be subjected to reduced pressure distillation, preferably under reduced pressure distillation conditions of 55-80° C., to remove excess phosphorus trichloride and solvent I to obtain the first reaction solution.

[0029] According to the present invention, preferably, in step (2), the amount of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl used is 0.3-0.5 mol relative to 1 mol of 2,2'-biphenol.

[0030] According to the present invention, preferably, the amount of the solvent II added is 1.8-2.5 mL relative to 1 g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl.

[0031] In order to further promote the smooth progress of the second reaction, preferably, the water content of the solvent II is not higher than 1000 mg / L.

[0032] According to the present invention, preferably, the solvent II is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran and 1,4-dioxane.

[0033] According to the present invention, preferably, the amount of the acid binding agent used is 1.2-1.8 mol relative to 1 mol of 2,2'-biphenol.

[0034] According to the present invention, preferably, the acid binding agent is selected from pyridine and / or triethylamine.

[0035] According to the present invention, preferably, the amount of the auxiliary agent used is 0.03-0.04 mol relative to 1 mol of the acid binding agent.

[0036] According to the present invention, preferably, the auxiliary agent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide and sodium hydroxide.

[0037] Furthermore, the auxiliary agent is N,N-dimethylformamide.

[0038] According to the present invention, preferably, the temperature of the second reaction is 25-75° C. and the time is 2-8 hours. Within this temperature and time range, the time of the second reaction is adjusted accordingly according to the temperature of the second reaction. When the temperature is higher, a shorter reaction time can achieve complete reaction. When the temperature is lower, in order to achieve complete reaction, the reaction time needs to be appropriately extended.

[0039] According to the present invention, preferably, the second reaction is carried out in the presence of a protective gas, which may be an inert gas and / or nitrogen. Preferably, the protective gas is nitrogen.

[0040] According to the present invention, preferably, the preparation method further comprises: separating the bidentate phosphite from the product obtained by the second reaction.

[0041] In order to easily separate the pure bidentate phosphite, preferably, the separation method includes: mixing the product obtained from the second reaction with solvent III, and then performing solid-liquid separation. Preferably, the solid-liquid separation is performed by filtration.

[0042] According to the present invention, preferably, the amount of the solvent III added is 3-7 mL relative to 1 g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl.

[0043] According to the present invention, preferably, the water content of the solvent III is not higher than 1000 mg / L.

[0044] According to the present invention, preferably, the solvent III is selected from alcohol and / or acetonitrile, preferably acetonitrile.

[0045] In order to further improve the purity of the bidentate phosphite, preferably, the preparation method further comprises: washing the solid material obtained after solid-liquid separation, for example, using alcohol and / or acetonitrile for washing, preferably using acetonitrile for washing.

[0046] In the present invention, the solvent I, solvent II and solvent III are all solvents that have been anhydrous treated. The anhydrous treatment method can be a method well known in the art. For example, the anhydrous treatment of tetrahydrofuran can be performed by placing the tetrahydrofuran reagent to be treated in a clean flask, passing nitrogen, adding appropriate sodium tablets, adding an appropriate amount of indicator benzophenone, and refluxing until the solution turns blue.

[0047] In the present invention, iron ions refer to trivalent iron ions.

[0048] The present invention will be described in detail below by way of examples. The examples involve the following test methods and reagents:

[0049] The purity of bidentate phosphite was determined by high performance liquid chromatography (Q / CRI001-2019.5).

[0050] The chloride ion content was detected by a chlorine element analyzer, and the iron ion content was detected by inductively coupled plasma mass spectrometry (ICP).

[0051] The yield is calculated based on 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl. The yield calculation formula is: yield % = [m2 ÷ 838] × purity ÷ [m1 ÷ 410]; m2 is the mass of the product; m1 is the mass of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl.

[0052] The water content of tetrahydrofuran is 50 mg / L; the water content of 2-methyltetrahydrofuran is 50 mg / L; the water content of 1,4-dioxane is 50 mg / L; and the water content of acetonitrile is 50 mg / L.

[0053] Example 1

[0054] Under nitrogen protection, the reaction was carried out in a three-necked flask equipped with a gas guide tube and a condenser. The tail gas was absorbed by alkali solution and then absorbed by water. First, 46.5 g of 2,2'-biphenol was added to a clean three-necked flask, followed by tetrahydrofuran (Solvent I) (1.5 mL per 1 g of 2,2'-biphenol). After stirring until dissolved, 43.5 mL of phosphorus trichloride was slowly added dropwise when the temperature reached 40°C (so that the molar ratio of phosphorus trichloride to 2,2'-biphenol was 2:1). After the addition was complete, the temperature was slowly raised to 60°C for the first reaction. After reacting for 1 hour, the temperature was cooled to room temperature. Excess phosphorus trichloride and solvent were distilled off under reduced pressure at 60°C, and the temperature was then cooled to room temperature. Then, N2 was introduced, and 24 mL of pyridine (so that the molar ratio of pyridine to 2,2'-biphenol was 1.2:1), 41 g of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl (so that the molar ratio of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol was 0.4:1), 0.66 g of N,N-dimethylformamide (so that the molar ratio of N,N-dimethylformamide to pyridine was 0.036:1) and tetrahydrofuran (solvent II) (so that the molar ratio relative to 1 g of pyridine was 0.036:1) were added to the mixture under stirring. A mixed solution of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl and tetrahydrofuran (the amount added is 1.8 mL) was slowly added dropwise to the above reaction solution. After the addition was completed, the temperature was raised to 50°C for a second reaction. After reacting for 2 hours, acetonitrile (solvent III) was added so that the amount of acetonitrile (solvent III) added was 3 mL relative to 1 g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl. After stirring to room temperature, the mixture was filtered and then washed with acetonitrile to obtain 60.86 g of a white solid product.

[0055] The product was confirmed by nuclear magnetic resonance analysis to be a bidentate phosphite of formula (1) with a purity of 99.12 wt% and a yield of 71.99%. In 1 kg of the bidentate phosphite product, the chloride ion content was 2.18 mg and the iron ion content was 0.47 mg.

[0056] Example 2

[0057] Under nitrogen protection, the reaction was carried out in a three-necked flask equipped with a gas guide tube and a condenser. The tail gas was absorbed by alkali solution and then absorbed by water. First, 46.5 g of 2,2'-biphenol was added to a clean three-necked flask, followed by tetrahydrofuran (Solvent I) (2.5 mL per 1 g of 2,2'-biphenol). After stirring until dissolved, 39 mL of phosphorus trichloride (so that the molar ratio of phosphorus trichloride to 2,2'-biphenol was 1.8:1) was slowly added dropwise when the temperature reached 40°C. After the addition was complete, the temperature was slowly raised to 65°C for the first reaction. After 1.5 hours of reaction, the temperature was cooled to room temperature. Excess phosphorus trichloride and solvent were distilled off under reduced pressure at 75°C, and the temperature was then cooled to room temperature. Then, N2 was introduced, and 50 mL of triethylamine (making the molar ratio of triethylamine to 2,2'-biphenol be 1.4:1), 41 g of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl (making the molar ratio of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol be 0.4:1), 1 g of N,N-dimethylformamide (making the molar ratio of N,N-dimethylformamide to triethylamine be 0.038:1) and 1,4-dioxane (solvent II) (making the molar ratio relative to 1 A mixed solution of 1g bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl and 2mL of 1,4-dioxane was slowly added dropwise to the above reaction solution. After the addition was completed, a second reaction was carried out at 30°C. After 7 hours of reaction, acetonitrile (solvent III) was added so that the amount of acetonitrile (solvent III) added was 4mL relative to 1g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl. After stirring to room temperature, the mixture was filtered and then washed with acetonitrile to obtain 60.97g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.14wt% and a yield of 72.13%. In 1kg of the bidentate phosphite product, the chloride ion content was undetectable and the iron ion content was 1.16mg.

[0058] Example 3

[0059] Under nitrogen protection, the reaction was carried out in a three-necked flask equipped with a gas guide tube and a condenser. The tail gas was absorbed by alkali solution and then absorbed by water. First, 46.5 g of 2,2'-biphenol was added to a clean three-necked flask, followed by tetrahydrofuran (Solvent I) such that the amount of tetrahydrofuran (Solvent I) added was 3.5 mL per 1 g of 2,2'-biphenol. After stirring until dissolved, 33 mL of phosphorus trichloride (so that the molar ratio of phosphorus trichloride to 2,2'-biphenol was 1.5:1) was slowly added dropwise when the temperature reached 40°C. After the addition was complete, the temperature was slowly raised to 70°C for the first reaction. After 2.5 hours of reaction, the temperature was cooled to room temperature. Excess phosphorus trichloride and solvent were distilled off under reduced pressure at 70°C, and the temperature was then cooled to room temperature. Then, N2 was introduced, and 56 mL of triethylamine (making the molar ratio of triethylamine to 2,2'-biphenol be 1.6:1), 30.75 g of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl (making the molar ratio of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol be 0.3:1), 0.88 g of N,N-dimethylformamide (making the molar ratio of N,N-dimethylformamide to triethylamine be 0.03:1) and 2-methyltetrahydrofuran (solvent II) (making the molar ratio of triethylamine to 2,2'-biphenol be 1.6:1) were added under ice bath and stirring. A mixed solution of 1g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl and 2-methyltetrahydrofuran (2.5mL) was slowly added dropwise to the above reaction solution. After the addition was complete, a second reaction was carried out at 25°C. After 8 hours of reaction, acetonitrile (solvent III) was added so that the amount of acetonitrile (solvent III) added was 7mL relative to 1g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl. After stirring to room temperature, the mixture was filtered and then washed with acetonitrile to obtain 45.32g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was a bidentate phosphite represented by formula (1), with a purity of 99.26wt% and a yield of 71.57%. In 1kg of the bidentate phosphite product, the chloride ion content was 2.32mg and the iron ion content was 1.43mg.

[0060] Example 4

[0061] Under nitrogen protection, the reaction was carried out in a three-necked flask equipped with a gas guide tube and a condenser. The tail gas was absorbed by alkali solution and then absorbed by water. First, 46.5 g of 2,2'-biphenol was added to a clean three-necked flask, followed by tetrahydrofuran (Solvent I) such that the amount of tetrahydrofuran (Solvent I) added was 2 mL per 1 g of 2,2'-biphenol. After stirring until dissolved, 65 mL of phosphorus trichloride (so that the molar ratio of phosphorus trichloride to 2,2'-biphenol was 3:1) was slowly added dropwise when the temperature reached 40°C. After the addition was complete, the temperature was slowly raised to 65°C for the first reaction. After reacting for 2 hours, the temperature was cooled to room temperature. Excess phosphorus trichloride and solvent were distilled off under reduced pressure at 80°C, and the temperature was then cooled to room temperature. Then, N2 was introduced, and 36 mL of pyridine (so that the molar ratio of pyridine to 2,2'-biphenol was 1.8:1), 51.25 g of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl (so that the molar ratio of 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol was 0.5:1), 1.3 g of N,N-dimethylformamide (so that the molar ratio of N,N-dimethylformamide to pyridine was 0.04:1) and 2-methyltetrahydrofuran (solvent II) (so that the molar ratio relative to 1 A mixed solution of 1g bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl and 2-methyltetrahydrofuran (2.5mL) was slowly added dropwise to the above reaction solution. After the addition was completed, the temperature was raised to 75°C for a second reaction. After 3 hours of reaction, acetonitrile (solvent III) was added so that the amount of acetonitrile (solvent III) added was 5mL relative to 1g bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl. After stirring to room temperature, the mixture was filtered and then washed with acetonitrile to obtain 75.87g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was a bidentate phosphite represented by formula (1) with a purity of 99.11wt% and a yield of 71.78%. In 1kg of the bidentate phosphite product, the chloride ion content was 1.68mg and the iron ion content was 0.91mg.

[0062] Example 5

[0063] A bidentate phosphite was prepared according to the method of Example 1, except that the molar ratio of phosphorus trichloride to 2,2'-biphenol was 1.2:1, yielding 57.28 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.01 wt% and a yield of 67.68%. The chloride ion content of 1 kg of the bidentate phosphite product was 10.04 mg, and the iron ion content was 3.85 mg.

[0064] Example 6

[0065] A bidentate phosphite was prepared according to the method of Example 1, except that the first reaction temperature was 90° C. and the reaction time was 0.5 hour, yielding 59.12 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.07 wt % and a yield of 69.89%. The chloride ion content of 1 kg of the bidentate phosphite product was 7.62 mg, and the iron ion content was 8.28 mg.

[0066] Example 7

[0067] A bidentate phosphite was prepared according to the method of Example 1, except that the molar ratio of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol was 0.2:1, yielding 27.44 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.02 wt% and a yield of 64.85%. The chloride ion content of 1 kg of the bidentate phosphite product was 8.47 mg, and the iron ion content was 4.51 mg.

[0068] Example 8

[0069] A bidentate phosphite was prepared according to the method of Example 1, except that the molar ratio of pyridine (acid binder) to 2,2'-biphenol was 1:1, yielding 57.89 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.04 wt% and a yield of 68.42%. The chloride ion content of 1 kg of the bidentate phosphite product was 11.59 mg, and the iron ion content was 1.44 mg.

[0070] Example 9

[0071] A bidentate phosphite was prepared according to the method of Example 1, except that the molar ratio of N,N-dimethylformamide (auxiliary agent) to pyridine (acid binding agent) was 0.025:1, yielding 58.46 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.02 wt% and a yield of 69.08%. The chloride ion content of 1 kg of the bidentate phosphite product was 9.18 mg, and the iron ion content was 2.27 mg.

[0072] Example 10

[0073] A bidentate phosphite was prepared according to the method of Example 1, except that the second reaction temperature was 80° C. and the reaction time was 2 hours, yielding 57.4 g of a white solid product. Nuclear magnetic resonance analysis confirmed that the product was the bidentate phosphite represented by formula (1), with a purity of 99.13 wt % and a yield of 67.9 wt %. The chloride ion content of 1 kg of the bidentate phosphite product was 8.74 mg, and the iron ion content was 2.32 mg.

[0074] It can be seen from the above results that the bidentate phosphites prepared in Examples 1-4 have high purity and yield, with a purity of more than 99 wt% and a yield of more than 70%; in 1 kg of bidentate phosphite product, the chloride ion content is less than 3 mg, the iron ion content is less than 2 mg, and there is no recrystallization step. Example 5 reduces the amount of phosphorus trichloride; Example 6 increases the temperature of the first reaction and shortens the time of the first reaction; Example 7 changes the molar ratio of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol; Example 8 changes the amount of the acid binding agent; Example 9 changes the amount of the auxiliary agent. Compared with Example 1, the purity and yield of the bidentate phosphite products obtained in Examples 5-9 are reduced to a certain extent, and the content of impurities such as chloride ions and iron ions in the bidentate phosphite products is increased; Example 10 increases the temperature of the second reaction. Compared with Example 1, the purity of the bidentate phosphite product obtained in Example 10 is higher, but the yield is reduced to a certain extent, and the content of impurities such as chloride ions and iron ions in the bidentate phosphite product is increased. This shows that when the molar ratio of phosphorus trichloride to 2,2'-biphenol, the conditions of the first reaction and the second reaction, the molar ratio of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl to 2,2'-biphenol, and the amounts of the acid-binding agent and the auxiliary agent meet the preferred ranges, the yield and purity of the obtained bidentate phosphite product can be further improved, and the content of impurities such as chloride ions and iron ions can be further reduced.

[0075] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for preparing a bidentate phosphite, characterized in that: The preparation method comprises the following steps: (1) mixing 2,2'-biphenol, phosphorus trichloride and solvent I to perform a first reaction to obtain a first reaction solution; (2) mixing the first reaction solution, bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl, an acid-binding agent, an auxiliary agent and a solvent II to carry out a second reaction to obtain a bidentate phosphite represented by formula (1).

2. The preparation method according to claim 1, characterized in that In step (1), phosphorus trichloride and 2,2'-biphenol are mixed in a molar ratio of (1.5-3):1; Preferably, the amount of the solvent I added is 1.3-3.5 mL relative to 1 g of 2,2'-biphenol.

3. The preparation method according to claim 1 or 2, characterized in that The water content of the solvent I is not higher than 1000 mg / L; Preferably, the solvent I is selected from at least one of 2-methyltetrahydrofuran, tetrahydrofuran and 1,4-dioxane.

4. The preparation method according to any one of claims 1 to 3, characterized in that The temperature of the first reaction is 60-70° C., and the time is 1-2.5 hours.

5. The preparation method according to any one of claims 1 to 4, characterized in that In step (2), the amount of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl used is 0.3-0.5 mol relative to 1 mol of 2,2'-biphenol; Preferably, the amount of the solvent II added is 1.8-2.5 mL relative to 1 g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl.

6. The preparation method according to any one of claims 1 to 5, characterized in that The water content of the solvent II is not higher than 1000 mg / L; Preferably, the solvent II is at least one selected from 2-methyltetrahydrofuran, tetrahydrofuran and 1,4-dioxane.

7. The preparation method according to any one of claims 1 to 6, characterized in that The amount of the acid binding agent used is 1.2-1.8 mol relative to 1 mol of 2,2'-biphenol; Preferably, the acid binding agent is selected from pyridine and / or triethylamine.

8. The preparation method according to any one of claims 1 to 7, characterized in that The amount of the auxiliary agent is 0.03-0.04 mol relative to 1 mol of the acid binding agent; Preferably, the auxiliary agent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide and sodium hydroxide, preferably N,N-dimethylformamide.

9. The preparation method according to any one of claims 1 to 8, characterized in that The temperature of the second reaction is 25-75° C., and the time is 2-8 hours.

10. The preparation method according to any one of claims 1 to 9, characterized in that: The preparation method further comprises: separating the bidentate phosphite from the product obtained by the second reaction; Preferably, the separation method comprises: mixing the product obtained by the second reaction with solvent III, and then performing solid-liquid separation; Preferably, the amount of solvent III added is 3-7 mL relative to 1 g of bisphenol 2,2'-dihydroxy-4,4',6,6'-tetra-tert-butyl-1,1'-biphenyl; Preferably, the water content of the solvent III is not higher than 1000 mg / L; Preferably, the solvent III is selected from alcohol and / or acetonitrile, preferably acetonitrile.

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