Nickel ligand bidentate phosphite suitable for adiponitrile synthesis and preparation method thereof

Abstract

The invention provides nickel ligand bidentate phosphite suitable for synthesis of adiponitrile and a preparation method of the nickel ligand bidentate phosphite. The method comprises the following three main steps: step S1: taking o-bromo p-methylphenol as a raw material, and adopting sodium methoxide catalyzed methoxylation reaction to prepare 2-methoxy-4-methylphenol at normal pressure in a temperature range of 80-100 DEG C; and S2, carrying out an oxidative coupling reaction on the 2-methoxy-4-methylphenol prepared in the step S1, a persulfate oxidant and an iron compound in a water medium to synthesize 3, 3 '-bis (methoxy)-5, 5-dimethyl-2, 2-diphenol. And S3, carrying out a reflux reaction on the diphenol obtained in the step S2, o-methylphenoxy phosphine chloride and diphenyl phosphine chloride in the presence of an acid-binding agent to finally obtain the target bidentate phosphite compound. The method provided by the invention has the characteristics of high efficiency and environmental protection, can successfully synthesize high-purity nickel ligand bidentate phosphite, and is suitable for catalytic synthesis of adiponitrile.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a nickel ligand bidentate phosphite suitable for adiponitrile synthesis and a preparation method thereof. Background Art

[0002] Adiponitrile is an important chemical intermediate, widely used in the synthesis of high-performance polyamide materials such as nylon-6,6. In the synthesis of adiponitrile, olefin hydrocyanation is a key step, and transition metal complex catalysts, especially nickel-based catalytic systems, have attracted much attention due to their high catalytic activity and good selectivity.

[0003] Among them, nickel complexes composed of bidentate phosphite ligands show excellent catalytic performance in this type of reaction. This type of ligand can not only improve the stability and reaction selectivity of the catalyst, but also effectively adjust the electronic and spatial structure of the catalytic center, thereby improving the catalytic efficiency of the entire reaction system. As an important representative of bidentate phosphite ligands, it has become a hot topic of research and industry because of its outstanding performance in catalyzing the hydrocyanation of butadiene to produce isomeric valeronitrile mixtures, and in promoting the isomerization of 2-methyl-3-butenenitrile and further hydrocyanation to produce adiponitrile.

[0004] However, there is little systematic research on the large-scale, industrializable synthesis route of this type of bidentate phosphite ligand in existing literature and technical data. Especially in the specific process of ligand synthesis, due to the activity of the phosphorus compound itself, side reactions such as esterification often occur, which seriously affect the yield and purity of the final product. At the same time, the key raw materials involved in the synthesis process, such as biphenol, are often synthesized by oxidative coupling of monophenols, with more by-products, and ketones or other impurities are easily generated, which further aggravates the difficulty of product purification. In addition, the limited source of raw materials and the high cost make the application of this type of ligand on an industrial scale face considerable obstacles.

[0005] Therefore, the existing technology still has the following major deficiencies in achieving the synthesis of high-purity bidentate phosphite ligands: (1) there are many side reactions, the reaction process is difficult to control, and the product yield is low; (2) the product is difficult to purify and is prone to carry impurities, which affects the performance of the catalyst; (3) the synthetic raw materials are expensive, which is not conducive to cost control; (4) there is a lack of economical and efficient large-scale production technology, which limits its wide application in industry.

[0006] In summary, there is an urgent need to develop a new preparation process that is green, environmentally friendly, easy to operate, has readily available raw materials and is suitable for industrial scale-up to meet the actual demand for bidentate phosphite ligands in high-performance olefin hydrocyanation catalysts. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a method for preparing a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, so as to solve the problems existing in the prior art of high raw material cost, many side reactions, difficulty in product purification, low yield and disadvantage for industrial mass production.

[0008] In order to overcome the above defects of the prior art, the present invention provides a method for preparing a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, comprising the following steps: S1: Synthesis of 2-methoxy-4-methylphenol: Using o-bromo-p-methylphenol as raw material, methoxylation reaction catalyzed by sodium methoxide was performed to obtain 2-methoxy-4-methylphenol; S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: 2-methoxy-4-methylphenol prepared in step S1 is mixed with an oxidant and an iron compound in an aqueous medium to form a mixed solution, and then subjected to an oxidative coupling reaction at a temperature of 0-100° C. to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; The oxidant is a persulfate anion, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is (1.2-1): (1-1.2), and the molar ratio of the 2-methoxy-4-methylphenol to the iron compound is (1.2-1): (0.0005-0.05); S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of an acid binding agent at 15-25°C to finally obtain the target bidentate phosphite compound.

[0009] Compared with the prior art, the preparation method of a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile in the present application has the following advantages: the present invention changes the traditional synthesis method that relies on high-cost raw materials and complex process paths to use o-bromo-p-methylphenol as the starting raw material, sequentially constructs a biphenyl skeleton through methoxylation and oxidative coupling reactions, and then introduces a phosphinate group under mild conditions to form a target ligand, thereby replacing the defects of the prior art that the raw materials are expensive, there are many by-products and it is difficult to purify; then, a persulfate oxidant and an iron compound catalytic system are used to prepare a biphenol intermediate through a simple and efficient oxidative coupling reaction, thereby avoiding the problems of generating a large number of by-products and difficulty in purification in the traditional oxidative coupling process; finally, through a suitable molar ratio and mild reaction conditions, a high-purity bidentate phosphite compound is successfully prepared, which significantly improves the yield and industrial applicability of the product.

[0010] In a possible implementation manner, the reaction formula of step S1 is as follows: .

[0011] In a possible embodiment, in step S1, the conditions of the methoxylation reaction are: under normal pressure, the system temperature is 80-100° C., the molar ratio of o-bromo-p-methylphenol to sodium methoxide is 1:(2.0-3.5), and N,N-dimethylformamide is used as a co-catalyst in the reaction.

[0012] Compared with the prior art, the above technical scheme is adopted to significantly improve the conversion rate of o-bromo-p-methylphenol by regulating a mild reaction temperature and a reasonable raw material ratio. At normal pressure and a suitable temperature, sodium methoxide efficiently methoxylates the hydroxyl group, with good reaction selectivity and few side reactions, so that the generated 2-methoxy-4-methylphenol has high purity and can be used in subsequent reactions without complicated purification treatment.

[0013] In a possible implementation, in step S2, the structural formula of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol is: .

[0014] In a possible embodiment, in step S2, the conditions of the oxidative coupling reaction are: the reaction is carried out at a temperature of 15-50° C., the oxidant is ammonium persulfate or an alkali metal persulfate, and the iron compound is ferric sulfate or ferric chloride.

[0015] Compared with the prior art, the above technical scheme uses ammonium persulfate or alkali metal persulfate as an oxidant, which can promote the reaction of 2-methoxy-4-methylphenol with an iron compound to form biphenol at a lower temperature (15-50°C), while maintaining a low incidence of side reactions, avoiding the generation of by-products that may be caused under high temperature conditions, and significantly improving the yield and purity of the target product.

[0016] In a possible implementation, in step S2, the oxidant is sodium persulfate or potassium persulfate, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is 1:1.

[0017] Compared with the prior art, the above technical solution ensures that the oxidation reaction is efficient and highly selective by precisely controlling the dosage of sodium persulfate or potassium persulfate. The persulfate oxidant can effectively promote the oxidative coupling reaction of 2-methoxy-4-methylphenol under mild conditions (15-50° C.) to generate high-purity biphenol. By precisely controlling the molar ratio of the oxidant to the raw material to be 1:1, the completeness of the oxidation reaction can be ensured, and the side reactions or waste of raw materials caused by excessive oxidant can be avoided, thereby significantly improving the yield and selectivity of the reaction. In addition, the use of sodium persulfate or potassium persulfate as an oxidant is both economical and environmentally friendly, reduces the burden on the environment, and improves the sustainability of the entire reaction process.

[0018] In a possible implementation, in step S2, the molar ratio of the 2-methoxy-4-methylphenol to the iron compound is 1:(0.002-0.02).

[0019] Compared with the prior art, the above technical solution can effectively promote the oxidative coupling reaction by precisely controlling the amount of the iron compound, while avoiding the side reactions or impurity generation caused by excessive iron compounds. The iron compound can be used as a catalyst to effectively catalyze the reaction at a lower molar ratio, avoiding the side reactions caused by excessive iron compounds, such as over-oxidation or the formation of unnecessary by-products. By adjusting the molar ratio of the iron compound to 2-methoxy-4-methylphenol to 1: (0.002-0.02), the high selectivity and high efficiency of the oxidative coupling reaction can be ensured, while reducing the amount of catalyst and the problem of iron residue in the reaction, significantly improving the purity of the product, and reducing the difficulty and cost of purification.

[0020] In a possible embodiment, after step S2 and before step S3, the step of preparing o-methylphenoxyphosphine chloride is further included, comprising: placing o-methylphenol and triethylamine into a reaction container, adding dry toluene, cooling the reaction mixture to -10°C, then dripping a pre-cooled toluene solution of phosphorus trichloride, and continuing to stir the reaction for 1-3 hours after the dripping is completed to obtain o-methylphenoxyphosphine chloride.

[0021] Compared with the prior art, the technical solution is adopted to precisely control the dripping rate of phosphorus trichloride at a relatively low temperature (-10°C), thereby avoiding side reactions that may occur at room temperature or high temperature, such as over-chlorination or generation of unnecessary impurities. The reaction rate can be effectively controlled by low-temperature reaction, and the excessive reaction of phosphorus trichloride can be reduced, thereby ensuring that the generated o-methylphenoxyphosphine chloride has a higher purity and reducing the generation of by-products. By using triethylamine as an acid-binding agent, the acidic substance generated by the reaction is effectively neutralized, thereby avoiding the influence of the acidic conditions of the reaction environment on the target product. Finally, the above steps act synergistically, the yield and purity of o-methylphenoxyphosphine chloride are significantly improved, and the difficulty and cost of subsequent purification are reduced.

[0022] In one possible embodiment, in step S3, the molar ratio of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to o-methylphenoxyphosphine chloride is 1:(0.9-1.2), the molar ratio of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to diphenylphosphine chloride is 1:(0.9-1.2), the acid binding agent is pyridine or triethylamine, and the reflux reaction time is 1-3 hours.

[0023] Compared with the prior art, the above technical solution is adopted to optimize the reflux reaction conditions by precisely controlling the molar ratio of the reactants and using a suitable acid-binding agent (pyridine or triethylamine), thereby improving the selectivity and efficiency of the reaction. The molar ratio of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to o-methylphenoxyphosphine chloride and diphenylphosphine chloride is controlled within the range of 1:(0.9-1.2), which can ensure that the phosphination reaction is carried out under mild conditions and avoid excessive or incomplete phosphination. Furthermore, by appropriately controlling the reflux reaction time (1-3 hours), a bidentate phosphite compound with high purity and high yield can be obtained without introducing too many by-products.

[0024] Another technical problem to be solved by the present invention is to provide a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, so as to solve the problems existing in the prior art of high raw material cost, many side reactions, difficulty in product purification, low yield and disadvantage for industrial large-scale production.

[0025] In order to overcome the defects of the above prior art, the present invention provides a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, wherein the nickel ligand bidentate phosphite is prepared by the above preparation method, and the chemical formula of the nickel ligand bidentate phosphite is: .

[0026] Compared with the prior art, the nickel ligand bidentate phosphite suitable for adiponitrile synthesis in the present application has the following advantages: Efficient synthesis route: The present invention successfully reduces costs and improves the conversion rate of raw materials and reaction efficiency by precisely controlling the conditions of methoxylation reaction, oxidative coupling reaction and phosphination reaction. Compared with the complex multi-step synthesis route in the prior art, the present invention provides a simple and efficient synthesis scheme, which is conducive to large-scale industrial production; Reduce side reactions and improve purity: The present invention uses a persulfate and iron compound catalytic system in the oxidative coupling reaction, which can effectively inhibit the occurrence of side reactions, improve the purity of the target product, and reduce the generation of impurities. Compared with the high reaction temperature and incomplete reaction commonly seen in traditional methods, the present invention can accurately control the reaction conditions and reduce side products and impurities; Improved yield and purity: The present invention improves the yield and purity of the target bidentate phosphite compound by optimizing the reaction ratio and reaction temperature. In the prior art, the product purity is often low due to side reactions and impurity generation. The present invention significantly improves the quality of the final product by reasonably controlling the conditions of each step, solving the problem of difficult product purification in the prior art; Low cost and environmental protection: The present invention uses cheap raw materials and catalysts, such as sodium methoxide, persulfate oxidant, etc., avoiding the use of expensive or toxic chemicals, making the reaction process more economical and environmentally friendly, and meeting the requirements of green chemistry; Through the above improvements, the present invention not only improves the economy and reaction efficiency of the adiponitrile synthesis process, but also makes the method more suitable for industrial large-scale production, solving the core problems of high raw material cost, complex process, low yield and difficult purification in the background technology. DETAILED DESCRIPTION

[0027] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0028] The present invention provides a method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis, comprising the following steps: S1: Synthesis of 2-methoxy-4-methylphenol: Using o-bromo-p-methylphenol as raw material, methoxylation reaction catalyzed by sodium methoxide was performed to obtain 2-methoxy-4-methylphenol; S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: 2-methoxy-4-methylphenol prepared in step S1 is mixed with an oxidant and an iron compound in an aqueous medium to form a mixed solution, and then subjected to an oxidative coupling reaction at a temperature of 0-100° C. to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; The oxidant is a persulfate anion, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is (1.2-1): (1-1.2), and the molar ratio of the 2-methoxy-4-methylphenol to the iron compound is (1.2-1): (0.0005-0.05); S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of an acid binding agent at 15-25°C to finally obtain the target bidentate phosphite compound.

[0029] As a preferred solution, the reaction formula of step S1 is as follows:

[0030] As a preferred solution, in step S1, the conditions of the methoxylation reaction are: under normal pressure, the system temperature is 80-100°C, the molar ratio of o-bromo-p-methylphenol to sodium methoxide is 1:(2.0-3.5), and N,N-dimethylformamide is used as a co-catalyst in the reaction.

[0031] As a preferred solution, in step S2, the structural formula of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol is: .

[0032] As a preferred solution, in step S2, the conditions of the oxidative coupling reaction are: the reaction is carried out at a temperature of 15-50° C., the oxidant is ammonium persulfate or alkali metal persulfate, and the iron compound is ferric sulfate or ferric chloride.

[0033] As a preferred solution, in step S2, the oxidant is sodium persulfate or potassium persulfate, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is 1:1.

[0034] As a preferred solution, in step S2, the molar ratio of 2-methoxy-4-methylphenol to the iron compound is 1:(0.002-0.02).

[0035] As a preferred solution, after step S2 and before step S3, the step of preparing o-methylphenoxyphosphine chloride is further included, comprising: placing o-methylphenol and triethylamine into a reaction container, adding dry toluene, cooling the reaction mixture to -10°C, then dripping a precooled toluene solution of phosphorus trichloride, and continuing to stir the reaction for 1-3 hours after the dripping is completed to obtain o-methylphenoxyphosphine chloride.

[0036] As a preferred scheme, in step S3, the molar ratio of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to o-methylphenoxyphosphine chloride is 1:(0.9-1.2), the molar ratio of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to diphenylphosphine chloride is 1:(0.9-1.2), the acid binding agent is pyridine or triethylamine, and the reflux reaction time is 1-3 hours.

[0037] The present invention also provides a nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, wherein the nickel ligand bidentate phosphite is prepared by the above-mentioned preparation method, and the chemical formula of the nickel ligand bidentate phosphite is: .

[0038] In combination with the above-mentioned range data scheme, embodiments of specific numerical values ​​are given below to further expand the technical scheme of the present invention: Embodiment 1:

[0039] This embodiment provides a nickel ligand bidentate phosphite suitable for adiponitrile synthesis and a preparation method thereof. The nickel ligand bidentate phosphite suitable for adiponitrile synthesis is prepared by the preparation method, and its chemical formula is as follows: ; The preparation method comprises the following steps: Step S1: Synthesis of 2-methoxy-4-methylphenol: using o-bromo-p-methylphenol as a raw material, under normal pressure, a system temperature of 90° C., a molar ratio of o-bromo-p-methylphenol to sodium methoxide of 1:2.75, using DMF as a co-catalyst, and a methoxylation reaction catalyzed by sodium methoxide to obtain 2-methoxy-4-methylphenol; The reaction formula of step S1 is as follows: .

[0040] Step S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: The 2-methoxy-4-methylphenol prepared in step S1 is mixed with sodium persulfate and ferric sulfate in an aqueous medium to form a mixed solution, wherein the molar ratio of 2-methoxy-4-methylphenol to the oxidant is 1:1, and the molar ratio of 2-methoxy-4-methylphenol to the iron compound is 1:0.01025, and an oxidative coupling reaction is carried out at 50° C. to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; The structural formula of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol is: .

[0041] Preparation of o-methylphenoxyphosphine chloride: o-methylphenol and triethylamine are placed in a reaction vessel, dry toluene is added, the reaction mixture is cooled to -10°C, and then a pre-cooled toluene solution of phosphorus trichloride is added dropwise. After the addition is completed, stirring and reacting is continued for 2 hours to obtain o-methylphenoxyphosphine chloride; Step S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of pyridine, wherein the molar ratio of biphenol to o-methylphenoxyphosphine chloride is 1:1.05, and the molar ratio of biphenol to diphenylphosphine chloride is 1:1.05, and the reaction is refluxed at 20°C for 2 hours to finally obtain the target bidentate phosphite compound. Example 2

[0042] This embodiment provides a nickel ligand bidentate phosphite suitable for adiponitrile synthesis and a preparation method thereof. The nickel ligand bidentate phosphite suitable for adiponitrile synthesis is prepared by the preparation method, and its chemical formula is as follows: ; The preparation method comprises the following steps: Step S1: Synthesis of 2-methoxy-4-methylphenol: using o-bromo-p-methylphenol as a raw material, under normal pressure, a system temperature of 80° C., a molar ratio of o-bromo-p-methylphenol to sodium methoxide of 1:2.0, using DMF as a co-catalyst, and a methoxylation reaction catalyzed by sodium methoxide to obtain 2-methoxy-4-methylphenol; Step S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: The 2-methoxy-4-methylphenol prepared in step S1 is mixed with sodium persulfate and ferric sulfate in an aqueous medium to form a mixed solution, wherein the molar ratio of 2-methoxy-4-methylphenol to the oxidant is 1:1, and the molar ratio of 2-methoxy-4-methylphenol to the iron compound is 1:0.002, and an oxidative coupling reaction is carried out at 15°C to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; Preparation of o-methylphenoxyphosphine chloride: o-methylphenol and triethylamine are placed in a reaction vessel, dry toluene is added, the reaction mixture is cooled to -10°C, and then a pre-cooled toluene solution of phosphorus trichloride is added dropwise. After the addition is completed, stirring and reacting is continued for 1 hour to obtain o-methylphenoxyphosphine chloride; Step S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of triethylamine, wherein the molar ratio of biphenol to o-methylphenoxyphosphine chloride is 1:0.9, and the molar ratio of biphenol to diphenylphosphine chloride is 1:0.9, and the reaction is refluxed at 15°C for 1 hour to finally obtain the target bidentate phosphite compound. Example 3

[0043] This embodiment provides a nickel ligand bidentate phosphite suitable for adiponitrile synthesis and a preparation method thereof. The nickel ligand bidentate phosphite suitable for adiponitrile synthesis is prepared by the preparation method, and its chemical formula is as follows: ; The preparation method comprises the following steps: Step S1: Synthesis of 2-methoxy-4-methylphenol: using o-bromo-p-methylphenol as a raw material, under normal pressure, a system temperature of 100° C., a molar ratio of o-bromo-p-methylphenol to sodium methoxide of 1:3.5, using DMF as a co-catalyst, and a methoxylation reaction catalyzed by sodium methoxide to obtain 2-methoxy-4-methylphenol; Step S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: The 2-methoxy-4-methylphenol prepared in step S1 is mixed with potassium persulfate and ferric chloride in an aqueous medium to form a mixed solution, wherein the molar ratio of 2-methoxy-4-methylphenol to the oxidant is 1:1, and the molar ratio of 2-methoxy-4-methylphenol to the iron compound is 1:0.02, and an oxidative coupling reaction is carried out at 50° C. to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; Preparation of o-methylphenoxyphosphine chloride: o-methylphenol and triethylamine are placed in a reaction vessel, dry toluene is added, the reaction mixture is cooled to -10°C, and then a pre-cooled toluene solution of phosphorus trichloride is added dropwise. After the addition is completed, stirring and reacting is continued for 3 hours to obtain o-methylphenoxyphosphine chloride; Step S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of pyridine, wherein the molar ratio of biphenol to o-methylphenoxyphosphine chloride is 1:1.2, and the molar ratio of biphenol to diphenylphosphine chloride is 1:1.2, and the reaction is refluxed at 25°C for 3 hours to finally obtain the target bidentate phosphite compound.

[0044] The following provides specific examples combining actual data and the purity of the reaction products to further explain the present invention: Example 4

[0045] S1: Synthesis of methoxy-4-methylphenol A 500ml three-necked flask is equipped with a stirrer, a thermometer, and a detachable reflux condenser. Put 1g of cuprous chloride and 166g of sodium methoxide (content 30%) into a 500ml flask, and then add 10g of DMF and 75g of o-bromo-p-cresol. Turn on stirring (300r / min) and start heating. When the temperature reaches 50℃, start counting the reaction time, and start keeping warm when heated to 90℃. Stop stirring and heating after 16h of reaction to obtain 246.5g of reaction liquid; The reaction solution was filtered at room temperature and washed with 10 g of methanol to obtain 208.8 g of filtrate. The filtrate was desolvated at 40°C and 1 kPa vacuum to obtain 98.8 g of desolvated product. Add 200 g of 15% aqueous sulfuric acid solution to the desolventized product for acidification. After acidification, stand and separate the layers. The upper layer is 2-methoxy-4-methylphenol and the lower layer is aqueous solution. Extract the aqueous layer three times with 261.6 g of toluene and stand and separate the layers. Combine the organic layer and 2-methoxy-4-methylphenol to obtain 316.6 g of organic layer. Desolventize at 40°C and 1 kPa vacuum to obtain 65.4 g of crude 2-methoxy-4-methylphenol. The crude product was distilled at 110°C and 1 kPa vacuum to obtain 52 g of 2-methoxy-4-methylphenol with a purity of about 98.6%.

[0046] S2: Synthesis of 3,3-di(methoxy)-5,5-dimethyl-2,2-biphenol A 5000ml three-necked flask equipped with a stirrer, a thermometer, and a detachable funnel device was added to 2-methoxy-4-methylphenol (122 g, 1.0 mol), FeSO4.7H2O (13.9 g) and water (1500 mL) at room temperature, and sodium persulfate (238 g) was added to the above mixture at room temperature. The resulting mixture was stirred at room temperature for more than 6 hours. The precipitated solid was collected by filtration, washed with water (3×500 ml), and vacuum dried at 50°C for one day to obtain 114 grams of product with a yield of 94% and a purity of about 95%. S2: Preparation of target bidentate phosphite compound 109 g of o-methylphenol (40 mmol) and 10.0 g of triethylamine (100 mmol) were put into a 2000 ml flask, and then 700 ml of dry toluene was added. The flask was cooled to -10 degrees ℃, and 200 ml of pre-cooled toluene solution (-10 ℃) containing 55 g of PCl3 (40 mmol) was added dropwise within 40 minutes; after stirring for about 1 hour, diphenylphosphine chloride (44 mmol) dissolved in 100 ml of toluene was added, and then 200 ml of a mixture of 57 g of 3,3,-di(methoxy)-5,5-dimethyl-2,2-bisphenol (40 mmol) toluene solution and 4 g of triethylamine (40 mmol) were added dropwise within 60 minutes, and stirred for 1 hour; heated to 20 ℃ and refluxed for reaction for 12 hours, the mixture was filtered, washed with 100 mL of toluene, and the solvent was desolvated under vacuum. The product was dried under vacuum overnight to obtain 140 g of product (A) with a purity of 98.7%. 31P NMR (C6D6): 132.5 ppm and 112.8 ppm.

[0047] It can be seen from the verification of Example 4 that the preparation method of the nickel ligand bidentate phosphite suitable for adiponitrile synthesis provided by the present invention has good practical feasibility: after methoxylation reaction of o-bromo-p-methylphenol at 90°C, 52g of 2-methoxy-4-methylphenol can be obtained after purification, with a purity of about 98.6%. Subsequently, the intermediate is subjected to an oxidative coupling reaction catalyzed by sodium persulfate and FeSO4·7H2O to obtain 114g of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol, with a yield of 94% and a purity of about 95%. Finally, the phosphination reaction is completed under mild conditions, and the target bidentate phosphite compound is successfully synthesized. The product is vacuum dried to obtain 140g with a purity of 98.7%. The entire process has mild reaction conditions, simple operation, and high product purity, which verifies the significant advantages of the present invention in optimizing processes, reducing side reactions, improving yields, and adapting to industrial production, and effectively solves the problems of low yields, many impurities, and complex synthetic routes in the prior art.

[0048] Through the above examples, it is further verified that the preparation method of the nickel ligand bidentate phosphite suitable for adiponitrile synthesis provided by the present invention has good feasibility and industrial adaptability. The synthetic route adopted uses o-bromo-p-methylphenol as the starting material, and successfully achieves the high-purity synthesis of the target ligand through efficient methoxylation, selective oxidative coupling and phosphination reaction under mild conditions. Combined with the overall technical principle of the present invention, it can effectively solve the technical problems such as expensive raw materials, harsh reaction conditions, difficult product purification, and many side reactions existing in the prior art, significantly improve the yield, reduce production costs, and have good process stability and large-scale application potential, which is suitable for the actual needs of industrial catalytic systems such as catalytic adiponitrile synthesis.

[0049] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" etc. means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0050] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis, characterized in that: The following steps are involved: S1: Synthesis of 2-methoxy-4-methylphenol: Using o-bromo-p-methylphenol as raw material, methoxylation reaction catalyzed by sodium methoxide was performed to obtain 2-methoxy-4-methylphenol; S2: Synthesis of 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol: 2-methoxy-4-methylphenol prepared in step S1 is mixed with an oxidant and an iron compound in an aqueous medium to form a mixed solution, and then subjected to an oxidative coupling reaction at a temperature of 0-100° C. to obtain 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol; The oxidant is a persulfate anion, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is (1.2-1): (1-1.2), and the molar ratio of the 2-methoxy-4-methylphenol to the iron compound is (1.2-1): (0.0005-0.05); S3: Synthesis of bidentate phosphite compound: 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol obtained in step S2 is reacted with o-methylphenoxyphosphine chloride and diphenylphosphine chloride in the presence of an acid binding agent at 15-25°C to finally obtain the target bidentate phosphite compound.

2. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: The reaction formula of step S1 is as follows: 。 3. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: In step S1, the conditions of the methoxylation reaction are: under normal pressure, the system temperature is 80-100° C., the molar ratio of o-bromo-p-methylphenol to sodium methoxide is 1:(2.0-3.5), and N,N-dimethylformamide is used as a co-catalyst in the reaction.

4. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: In step S2, the structural formula of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol is: 。 5. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: In step S2, the conditions of the oxidative coupling reaction are: the reaction is carried out at a temperature of 15-50° C., the oxidant is ammonium persulfate or alkali metal persulfate, and the iron compound is ferric sulfate or ferric chloride.

6. The method for preparing the nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 5, characterized in that: In the step S2, the oxidant is sodium persulfate or potassium persulfate, and the molar ratio of the 2-methoxy-4-methylphenol to the oxidant is 1:

1.

7. The method for preparing the nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 5, characterized in that: In the step S2, the molar ratio of the 2-methoxy-4-methylphenol to the iron compound is 1:(0.002-0.02).

8. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: After step S2 and before step S3, the method further comprises the step of preparing o-methylphenoxyphosphine chloride, comprising: putting o-methylphenol and triethylamine into a reaction container, adding dry toluene, cooling the reaction mixture to -10°C, then dripping a precooled toluene solution of phosphorus trichloride, and continuing to stir the reaction for 1-3 hours after the dripping is completed, so as to obtain o-methylphenoxyphosphine chloride.

9. The method for preparing a nickel ligand bidentate phosphite suitable for adiponitrile synthesis according to claim 1, characterized in that: In the step S3, the molar ratio of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to o-methylphenoxyphosphine chloride is 1:(0.9-1.2), the molar ratio of the 3,3'-di(methoxy)-5,5-dimethyl-2,2-biphenol to diphenylphosphine chloride is 1:(0.9-1.2), the acid binding agent is pyridine or triethylamine, and the reflux reaction time is 1-3 hours.

10. A nickel ligand bidentate phosphite suitable for the synthesis of adiponitrile, characterized in that: The nickel ligand bidentate phosphite is prepared by the preparation method according to any one of claims 1 to 9, and the chemical formula of the nickel ligand bidentate phosphite is: 。

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