Spiroene-based bidentate phosphine ligand as well as preparation method and application thereof

Abstract

The invention discloses a bidentate phosphine ligand as shown in the following general formula 1 and a preparation method thereof, and a nickel-based catalyst containing the ligand and a preparation method and application of the nickel-based catalyst. The bidentate phosphine ligand is a compound containing a helicene substructure, wherein the helicene substructure is a skeleton of the bidentate phosphine ligand. The bidentate phosphine ligand and the catalyst prepared from the bidentate phosphine ligand have high capability of catalyzing 1, 3-butadiene and 2M3BN, the conversion rate and the selectivity are obviously improved, the property of the catalyst is stable, and the catalytic performance is not obviously reduced after multiple times of cyclic application. General formula 1

Description

Technical Field

[0001] This invention relates to the field of fine chemicals, specifically to a bidentate phosphine ligand based on a helene derivative, its preparation method and application, as well as a nickel-based catalyst containing the ligand, its preparation method and application. Background Technology

[0002] Adiponitrile is a core intermediate in the production of Nylon-66, and its efficient synthesis is crucial for the chemical industry. Among numerous synthetic routes, the butadiene hydrocyanation method has become the mainstream industrial process due to its high atom economy. This process mainly includes three key steps: First, butadiene reacts with hydrogen cyanide in the presence of a zero-valent nickel catalyst to produce a mixture of 3-pentenonitrile and 2-methyl-3-butenonitrile; subsequently, the non-target product 2-methyl-3-butenonitrile needs to be converted to 3-pentenonitrile through an isomerization reaction; finally, 3-pentenonitrile reacts with a second molecule of hydrogen cyanide to generate the target product, adiponitrile.

[0003] In this multi-step reaction process, the design of the catalytic system, especially the selection of ligands, plays a decisive role in the economy and efficiency of the entire process. The performance of homogeneous nickel catalysts depends to a large extent on the electronic properties and spatial structure of the ligands, which together regulate the catalytic activity and selectivity of the nickel center.

[0004] Currently, various phosphorus ligands, especially monodentate phosphite ligands, are widely used in industry. However, these traditional ligands face significant technical bottlenecks in practical applications: First, phosphite bonds are sensitive to moisture and high temperatures, and are prone to degradation under reaction conditions, leading to catalyst deactivation; second, monodentate ligands have limited regioselectivity control over the first-step hydrocyanation reaction of butadiene, making it difficult to effectively increase the proportion of the target product 3-pentenonitrile; furthermore, due to their weak coordination ability, traditional ligands are unable to effectively stabilize the nickel center, resulting in easy catalyst deactivation and a short lifespan.

[0005] To overcome these shortcomings, researchers have begun to focus on bidentate phosphorus ligands. Bidentate ligands can form more stable complexes with metal centers through chelation effects, thereby improving catalyst stability. However, most existing bidentate phosphorus ligands still have limitations in stereoselectivity control; the flexibility of their molecular structure and limited chiral environment restrict further improvements in selectivity.

[0006] Helicene, as an aromatic compound with unique helical chirality and a rigid three-dimensional framework, offers new insights for the design of novel ligands. Its non-planar helical structure provides a strong chiral environment, while the rigid framework effectively fixes the spatial configuration of the ligand. Based on these properties, developing novel bidentate phosphorus ligands using helicene as the framework holds promise for combining the stereocontrol advantages of helicene with the stability of bidentate ligands, creating a novel catalytic system capable of simultaneously addressing stability, selectivity, and lifetime issues. This is of great significance for advancing the innovative development of butadiene hydrocyanation technology. Summary of the Invention

[0007] To address the shortcomings of existing technologies and the demands of industrial production, this invention provides a bidentate phosphorus ligand with a helicene backbone and its preparation method, as well as a catalyst solution system containing this ligand and its preparation method. The invention also describes the application of this catalyst solution system in the hydrocyanation reaction of 1,3-butadiene with hydrogen cyanide to produce 3-pentenonitrile (3PN) and 2-methyl-3-butenonitrile (2M3BN), and the isomerization of 2M3BN to 3PN. This catalyst solution system possesses advantages such as high catalytic activity, stable properties, and ease of preparation, which is beneficial in solving existing problems in the adiponitrile industry.

[0008] According to one aspect of the present invention, one object of the present invention is to provide a bidentate phosphine ligand, said bidentate phosphine ligand being a compound containing a helicene substructure, the general structural formula of which is shown in General Formula 1 below, wherein the helicene substructure forms the backbone of the bidentate phosphine ligand:

[0009] General Formula 1 Preferably, n is selected from an integer from 0 to 10, for example, it can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, and preferably 1; Preferably, R1 is selected from phenylene, ortho-C1-C6 alkylphenylene, meta-C1-C6 alkylphenylene, p-C1-C6 alkylphenylene, ortho-C1-C6 alkoxyphenylene, meta-C1-C6 alkoxyphenylene, p-C1-C6 alkoxyphenylene, 1-naphthylene, 2-naphthylene, cyclohexylene, 2,4-dimethylphenyl, 2,4-di-tert-butylphenyl, and 2,4-dimethoxyphenyl; Preferably, R2 is selected from phenyl, ortho-C1-C6 alkylphenyl, meta-C1-C6 alkylphenyl, p-C1-C6 alkylphenyl, ortho-C1-C6 alkoxyphenyl, meta-C1-C6 alkoxyphenyl, p-C1-C6 alkoxyphenyl, 1-naphthyl, 2-naphthyl, cyclohexyl, tert-butyl, 2,4-dimethylphenyl, 2,4-di-tert-butylphenyl, and 2,4-dimethoxyphenyl; Preferably, R1 is selected from phenylene, o-methylphenylene, m-methylphenylene, p-methylphenylene, o-methoxyphenylene, m-methoxyphenylene, p-methoxyphenylene, o-ethoxyphenylene, m-ethoxyphenylene, p-ethoxyphenylene, o-propoxyphenylene, m-propoxyphenylene, and p-propoxyphenylene.

[0010] Preferably, R2 is selected from phenyl, o-methylphenyl, m-methylphenyl, p-methylphenyl, o-methoxyphenyl, m-methoxyphenyl, p-methoxyphenyl, o-ethoxyphenyl, m-ethoxyphenyl, p-ethoxyphenyl, o-propoxyphenyl, m-propoxyphenyl, and p-propoxyphenyl.

[0011] According to another aspect of the present invention, a second object of the present invention is to provide a method for preparing the spiroene bidentate phosphine ligand, the method comprising the following two steps:

[0012] The method includes the following steps: Step 1: Compound 2 and compound 3 undergo a coupling reaction to obtain compound 4; Step 2: After compound 5 reacts with phosphorus trichloride for a period of time, compound 4 is added to continue the reaction, and finally the bidentate phosphine ligand 1 can be obtained, wherein R1, R2 and n are the same as defined above.

[0013] In step 1: The coupling reaction is carried out in an organic solvent or a mixed solution of organic solvent and water, and in the presence of a noble metal palladium catalyst and a base, and heated to a certain temperature.

[0014] Preferably, the organic solvent is selected from tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, dioxane, chloroform, dichloromethane, ethyl acetate, DMSO, N-methylpyrrolidone, or a mixture thereof with water, more preferably a mixture of tetrahydrofuran and water. Preferably, the volume ratio of the organic solvent to water is selected from 1:10 to 10:1, more preferably 2:1; Preferably, the molar ratio of compound 2 to compound 3 is selected from 1:10 to 10:1, and more preferably 1:2; Preferably, the noble metal palladium catalyst is selected from Pd(PPh3)4, Pd(dppf)Cl2, Pd2(dba)3, Pd(OAc)2, Pd / XPhos and Pd / SPhos systems, and is preferably Pd(PPh3)4; Preferably, the ratio of the amount of the noble metal palladium catalyst Pd(PPh3)4 to the mass of compound 2 is selected from 1% to 50%, preferably 10%; Preferably, the alkali is mainly selected from K2CO3, Cs2CO3, Na2CO3, K3PO4, potassium tert-butoxide, sodium tert-butoxide, potassium hydroxide, sodium hydroxide, cesium fluoride, potassium fluoride, tetrabutylammonium fluoride, etc., and more preferably K2CO3; Preferably, the molar ratio of the base to compound 2 is 1:10-10:1, more preferably 2:1; Preferably, the reaction temperature is 30°C-150°C, more preferably 90°C; Preferably, the reaction time is 30 min to 24 h, more preferably 6 h; In step 2: Compound 5 is first dissolved in an organic solvent at a reaction temperature of t1. Then, phosphorus trichloride is added dropwise. After the addition is complete, nitrogen gas is introduced and the reaction is carried out at temperature t1 for a period of time h1. The reaction temperature is then raised to t2, and compound 4 is dissolved in an organic solvent and added to the reaction solution. The reaction is continued for a period of time h2. Then, the temperature is raised to t3, and the reaction is carried out for a period of time h3 to obtain the final helicene bidentate phosphine ligand as shown in general formula 1.

[0015] Preferably, the molar ratio of compound 4 : compound 5 : phosphorus trichloride is 1 : 1-50 : 1-50; more preferably, it is 1 : 4 : 2. Preferably, the organic solvent is an inert organic solvent, such as benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, etc., with toluene being the most preferred. Preferably, the mass ratio of compound 4 to organic solvent is 1:0.1-50, more preferably 1:3; Preferably, the mass ratio of compound 5 to organic solvent is 1:0-50, more preferably 2:1; Preferably, the nitrogen flow rate is 0.01 NL / min to 10 NL / min, more preferably 0.3 NL / min; Preferably, the temperature t1 is -50℃ to 70℃, more preferably 25℃; Preferably, the time h1 is 30 min to 5 h, more preferably 1 h; Preferably, the temperature t2 is 25℃-200℃, more preferably 50℃; Preferably, the time h2 is 30 min to 5 h, more preferably 2 h; Preferably, the temperature t3 is 5℃-200℃, more preferably 110℃; Preferably, the time h3 is 1h-24h, more preferably 12h.

[0016] In some embodiments, compound 2 can be prepared by the following method, with n=1 as an example.

[0017] The method includes the following steps: S1: Compound S1-1 and compound S1-2 undergo a Wittig reaction to give compound S1-3; S2: Compound S1-3 is synthesized into S1-4 via a photochemical reaction.

[0018] In step S1: Step S1 can be carried out in the presence of an organic solvent and a certain amount of alkali: Preferably, the organic solvent is selected from benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, etc., and is preferably dichloromethane; Preferably, the alkali is selected from sodium hydroxide, potassium hydroxide, potassium tert-butoxide, sodium tert-butoxide, calcium hydroxide, ammonia, etc., with sodium hydroxide being the most preferred. Preferably, the molar ratio of compound S1-1 to compound S1-2 is 10:1 to 1:10, more preferably 2:1; Preferably, the reaction temperature is -50℃ to 100℃, and more preferably 0℃ to 30℃; Preferably, the reaction time is 30 min to 12 h, and more preferably 6 h.

[0019] In step S2: In step S2, the intermediate S1-3 obtained in step S1 is dissolved in organic solvent 1, and then organic solvent 2 and an initiator are added. Under light irradiation, S1-4 can be obtained. Preferably, the organic solvent 1 is selected from, for example, benzene, toluene, chlorobenzene, chloroform, acetonitrile, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, propylene oxide, etc., and more preferably toluene; Preferably, the initiator is selected from iodine, tetracyanobenzene, tetracyano-p-benzoquinone dimethane, dicyanobenzene, 1,4-dicyanonaphthalene, 9,10-dicyanoanthracene, tetrachloro-1,4-benzoquinone, benzophenone, etc., and more preferably iodine; Preferably, the organic solvent 2 is selected from, for example, benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, propylene oxide, propylene oxide, etc., and more preferably propylene oxide; Preferably, the irradiation light is selected from ultraviolet light, visible light, and infrared light, and more preferably ultraviolet light; Preferably, the reaction temperature is 0℃-100℃, more preferably 25℃; Preferably, the reaction time is 1 to 7 days, more preferably 3 days.

[0020] According to a third objective of the present invention, another objective of the present invention is to provide a catalyst represented by Formula 2 below, said catalyst comprising the above-mentioned helicene bidentate phosphine ligand, wherein a metal atom or ion forms a coordination bond with a phosphorus atom in the above-mentioned helicene bidentate phosphine ligand, thereby obtaining the corresponding catalyst:

[0021] Formula 2 Preferably, the metal atoms or metal ions are selected from cobalt, nickel, platinum, ruthenium, rhodium, iridium, etc., with nickel being the most preferred.

[0022] According to a fourth objective of the present invention, another objective of the present invention is to provide a method for preparing the catalyst solution system containing the helene bidentate phosphine ligand, the preparation method comprising: as shown in reaction formula 1, in an anhydrous and oxygen-free environment, in a certain organic solvent and nitrile dispersant, mixing a large excess of metal powder or metal salt and the bidentate phosphine ligand and heating for a period of time, wherein the metal powder or metal salt forms coordination bonds with the phosphorus atoms in the bidentate phosphine ligand, thereby obtaining the corresponding target catalyst:

[0023] Reaction 1 Preferably, the metal or its salt is selected from cobalt, nickel, platinum, ruthenium, rhodium, iridium metal powder or their salts, more preferably nickel or nickel salts, and even more preferably nickel powder; Preferably, the metal salt is selected from hydrochloride, nitrate, sulfate, sulfite, bisulfate, carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, acetate, etc., and more preferably hydrochloride or nitrate.

[0024] Preferably, the particle size of the nickel powder is 1μm-100μm, more preferably 10μm-15μm; Preferably, the mass ratio of the helene bidentate phosphine ligand to the metal or metal salt is selected from 1:1-50, more preferably 1:1.5-3; Preferably, the organic solvent is selected from benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, benzophenol, etc., and more preferably toluene; Preferably, the mass ratio of the helene bidentate phosphine ligand to the organic solvent is selected from 1:1-200, and more preferably 1:30; Preferably, the nitrile dispersant is selected from acetonitrile, propionitrile, acrylonitrile, benzonitrile, adiponitrile, trichloroacetonitrile, bromobenzonitrile, 3-pentenonitrile, 2-pentenonitrile, etc., and more preferably 3-pentenonitrile; Preferably, the mass ratio of the helene bidentate phosphine ligand to the nitrile dispersant is 1:1-100, more preferably 1:10; Preferably, the reaction temperature is 50℃-100℃, more preferably 110℃; Preferably, the reaction time is 1 hour to 24 hours, more preferably 12 hours; After the reaction is complete, the resulting catalyst solution system is stored under anhydrous and oxygen-free low-temperature conditions.

[0025] According to a fifth objective of the present invention, another objective of the present invention is to provide a method for preparing 3PN by hydrocyanation reaction of 1,3-butadiene with hydrogen cyanide, the method comprising: adding hydrogen cyanide, 1,3-butadiene and the catalyst solution system to a reactor, reacting for a period of time under certain temperature and anhydrous and oxygen-free conditions, and after the reaction is completed, obtaining 2-methyl-3-butenonitrile (2M3BN) and 3-pentenonitrile (3-PN), removing excess olefinic substances, and analyzing the composition and distribution of the products using gas chromatography.

[0026] Preferably, the molar ratio of hydrocyanic acid to olefins is selected from 1:0.1-10, and more preferably 1:1; Preferably, the amount of catalyst solution used is 1%-50% of the mass of the olefinic substance, and more preferably 10%. Preferably, the reaction temperature is selected from 20℃ to 100℃, and more preferably 60℃; Preferably, the reaction time is selected from 10 min to 5 h, and more preferably 20 min.

[0027] According to a sixth objective of the present invention, another objective of the present invention is to provide a method for isomerizing 2M3BN to 3PN, comprising: adding 2M3BN or a mixture of 2M3BN and 3PN to a reactor, adding a certain amount of the catalyst solution system, and allowing the reaction system to react for a period of time under certain temperature and anhydrous and oxygen-free conditions to obtain the isomerized product 3PN.

[0028] Preferably, the 2M3BN or the mixture of 2M3BN and 3PN is a reaction solution containing 95wt%-98wt% of 2M3BN raw material; Preferably, the amount of the catalyst solution system is 1wt%-50wt% of the mass of 2M3BN, and more preferably 10wt%. Preferably, the reaction temperature is 50℃-200℃, and more preferably 100℃-110℃; Preferably, the reaction time is 15 min-60 min, and more preferably 20 min-30 min.

[0029] Beneficial effects Compared with the prior art, the bidentate phosphine ligand and the catalyst prepared therefrom of the present invention have the following advantages: 1. The catalyst prepared by the method of the present invention has a high ability to catalyze 1,3-butadiene and 2M3BN, and the conversion rate and selectivity are significantly improved. 2. The catalyst system prepared by the method of the present invention has good selectivity. In the reaction of 1,3-butadiene and 2M3BN, there are fewer by-products, which ensures high yield and facilitates post-processing, and can protect the catalyst from deactivation. 3. The catalyst prepared by the method of the present invention has high activity and significantly improves the reaction rate in the reaction of 1,3-butadiene and 2M3BN, laying the foundation for continuous production. 4. The catalyst prepared by the method of the present invention does not require the addition of Lewis acid as an auxiliary agent in the catalytic isomerization reaction of 2M3BN, thus reducing costs and post-processing procedures; 5. The catalyst prepared by the method of the present invention is stable and its catalytic performance does not decrease significantly after multiple cycles. Detailed Implementation

[0030] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments.

[0031] Unless otherwise expressly stated, numerical ranges throughout the application include any subranges therein and any numerical values ​​incremented by the smallest subunit of a given value. Unless otherwise expressly stated, numerical values ​​throughout the application represent an approximate measure or limitation of the range of embodiments including minor deviations from a given value and having approximately the mentioned value as well as having the mentioned precise value. Except in the detailed description of the working embodiments provided at the end, all numerical values ​​of parameters (e.g., quantities or conditions) in this application (including the appended claims) should in all cases be understood to be modified by the term “approximately,” regardless of whether “approximately” actually precedes the numerical value. “Approximately” indicates that the stated numerical value allows for slight inaccuracies (some close to precision at that value; approximately or reasonably close to the value; approximate). If the inaccuracy provided by “approximately” is not understood in this common sense in the art, then “approximately” as used herein at least indicates a variation that can be produced by common methods of measuring and using these parameters. For example, “approximately” can include variations less than or equal to 10%, less than or equal to 5%, less than or equal to 4%, less than or equal to 3%, less than or equal to 2%, less than or equal to 1%, or less than or equal to 0.5%.

[0032] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0033] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0034] Example 1: Preparation of 2,13-dibromo-[5]helicene (compound S1-4)

[0035] Step S1: In a 1000 mL round-bottom flask, 4-bromobenzaldehyde (8.04 g, 60.0 mmol), p-xylenebis(triphenylphosphine chloride) (20.99 g, 30.0 mmol), and 500 mL of dichloromethane were added sequentially until completely dissolved. The flask was then placed in an ice-water bath and cooled to 0 °C. Next, 40.0 mL of 50% sodium hydroxide solution was slowly added dropwise. The ice-water bath was then removed, and the temperature was raised to 30 °C. Timing was started, and the reaction was carried out for 6 hours. Then, 250 mL of water was added, and the organic phase was separated. The organic phase was washed with water, dried over anhydrous sodium sulfate, and the organic solvent was removed under reduced pressure to obtain the crude product. The crude product was then quickly passed through diatomaceous earth for impurity removal; no further impurity removal was required, and it could be directly used in the next reaction step. Step S2: Add the crude product obtained in step S1 to a 2000 mL round bottom flask, then add 1400 mL of toluene, 100 mL of propylene oxide and iodine (5.0 g), replace with nitrogen, place it under ultraviolet light and react for 3 days, then remove the organic solvent under reduced pressure, and purify the crude product by column chromatography (mobile phase: dichloromethane: n-hexane = 1:5) to obtain pure 2,13-dibromo-[5]spiroene (10.87 g, total yield 83.5%).

[0036] Example 2: Preparation of 2,13-di-p-phenol-[5]helicene (compound 4)

[0037] In a 1000 mL round-bottom flask, 10.0 g of 2,13-dibromo-[5]spirolene (10.0 g, 23.05 mmol), 1.59 g of p-hydroxyphenylboronic acid (11.52 mmol), 1.0 g of Pd(PPh3)4, and 6.37 g of potassium carbonate (46.10 mmol) prepared in Example 1 were added in sequence. Finally, 600 mL of a mixed solvent of tetrahydrofuran and water (volume ratio 2:1) was added. After deoxygenation, the temperature was raised to 90 °C and the reaction was carried out for 6 h. Then, dichloromethane was added to extract the reaction solution, washed with water, dried with anhydrous sodium sulfate, and the organic solvent was removed. The crude product was then purified by column chromatography (mobile phase: dichloromethane: methanol = 10:1) to obtain pure 2,13-di-p-phenol-[5]spirolene (10.58 g, 98.5%). Example 3: [5] Preparation of helene bidentate phosphine ligand (compound 1)

[0038] Add m-cresol (324.4 g, 3 mol) and toluene (162.2 g) to a 2000 mL round-bottom flask, then place it at 25 °C and add phosphorus trichloride (206 g, 1.5 mol) dropwise to the reaction solution. After the addition is complete, introduce nitrogen gas at 0.3 NL / min into the reaction solution and react for 1 h. Then raise the temperature of the reaction solution to 50 °C, weigh 2,13-di-p-phenol-[5]spiroene (347 g, 0.75 mol) prepared in Example 2 and dissolve it in toluene (1041 g), then add it dropwise to the reaction solution. After the addition is complete, continue the reaction for 2 h. Finally, raise the temperature of the reaction solution to 110 °C and react for 12 h. After the reaction was completed, the organic solvent was removed under reduced pressure, and the resulting solid was dissolved in dichloromethane solution. Methanol was added, and a precipitate was formed. After repeating this process three times, the precipitate was dried under reduced pressure. The resulting solid was [5] helicene bidentate phosphine ligand (656.9 g, 92.1%). This product does not require further purification and can be directly used for the preparation of catalysts.

[0039] Example 4: Preparation of Ni-based catalyst (NiL4) containing [5] helene bidentate phosphine ligand

[0040] In a 500 mL round-bottom flask, 50 g of [5]-helicene bidentate phosphine ligand, 75 g of nickel powder, and 150 g of adiponitrile were added sequentially. After removing water and oxygen, the temperature of the reaction solution was raised to 110 °C and reacted for 12 h. After the reaction was completed, the temperature was lowered to room temperature, the reaction solution was centrifuged, and the upper oily viscous liquid was taken out. According to ICP detection, the content of the [5]-helicene bidentate phosphine ligand-based Ni-based catalyst (denoted as NiL4, where L is [5]-helicene bidentate phosphine ligand) in the oily viscous liquid was 59%.

[0041] Application Example 1: The hydrocyanation reaction of 1,3-butadiene with hydrogen cyanide catalyzed by a Ni-based catalyst (NiL4) containing [5] helicene bidentate phosphine ligand. In a 1000mL reactor of 316L, a pressure gauge, thermometer, stirrer, nitrogen purging and hydrogen cyanide inlet were installed. 40.0g of Ni-based catalyst (NiL4) containing [5]helicene bidentate phosphine ligand obtained in Example 4 was added to the reactor. Nitrogen purging was performed. At low temperature, liquid 1,3-butadiene (400g) and hydrogen cyanide (200g) were introduced. The reactor was sealed and the system was heated to 60℃. The reaction was carried out for 20min. After the reaction was completed, the hydrogen cyanide content in the nitrogen was detected to be below 100ppm. The temperature was lowered and the reactor was opened. The product was analyzed by GC. The actual effect of the reaction is shown in Table 1.

[0042] Application Example 2: Isomerization of 2M3BN catalyzed by Ni-based catalyst (NiL4) containing [5] helene bidentate phosphine ligand. In a 1000 mL 316 L reactor, 400 g of reaction solution (the specific composition of the reaction solution is shown in Table 2) was added, followed by 40.0 g of the Ni-based catalyst (NiL4) solution containing [5] helicene bidentate phosphine ligand obtained in Example 4. After nitrogen purging, the reaction temperature was raised to 110 °C and reacted for 20 min. The temperature was then lowered to end the reaction. The actual effect of the reaction was determined by gas chromatography, and the reaction results are shown in Table 2.

[0043] Application Example 3: Experiment on the application of the catalyst from Application Example 1 Using the catalyst solution from Application Example 1, a cyclic reuse experiment was conducted, with the same operation method as in Example 1. The reuse was repeated 10 times, and the experimental results are summarized in Table 1.

[0044] Application Example 4: Catalyst Application Experiment of Application Example 2 Using the catalyst solution from Application Example 2, a cyclic reuse experiment was conducted, with the same operation method as in Example 2. The reuse was repeated 10 times, and the experimental results are summarized in Table 2.

[0045] Comparative Application Example 1: Preparation of a catalyst containing a tri-m-methoxyphosphite ligand (denoted as NiL'4) and its application in the hydrocyanation of 1,3-butadiene. In the comparative examples, the preparation of the tri-methoxyphosphite ligand was performed according to the method described in GM Kosolapoff, “Organophosphorus Compounds”, John Wiley and Sons, Inc., New York, NY, 1950, p 184.

[0046] The catalyst was prepared in the same manner as in Example 4, except that 50 g of tri-m-methoxyphosphite ligand, 75 g of nickel powder, and 150 g of adiponitrile were added. After the reaction was completed, excess nickel powder was removed by centrifugation to obtain an oily, viscous catalyst liquid (NiL'4, where L' is tri-m-methoxyphosphite).

[0047] Hydrocyanation of 1,3-butadiene: In a 1000 mL reactor of 316 L, a pressure gauge, thermometer, stirrer, nitrogen purging and hydrogen cyanide inlet were installed. 40.0 g of the Ni-based catalyst (NiL'4) containing [5] helicene bidentate phosphine ligand obtained in Example 4 was added to the reactor. Nitrogen purging was performed. At low temperature, liquid 1,3-butadiene (400 g) and hydrogen cyanide (200 g) were introduced. The reactor was sealed and the system was heated to 60 °C. The reaction was carried out for 20 min. After the reaction, the hydrogen cyanide content in the nitrogen was found to be below 100 ppm. The temperature was lowered and the reactor was opened. The product was analyzed by GC. The reaction results are shown in Table 1.

[0048] Comparative Application Example 2: Catalysis of the isomerization reaction of 2M3BN using a catalyst containing a tri-methoxyphosphite ligand. After adding the reaction solution and catalyst solution (NiL'4), an additional 0.5 g of anhydrous zinc chloride was added as an auxiliary agent using current industrial technology. Furthermore, the reaction time was 120-150 min. Other operations were the same as in Application Example 2, and the product was analyzed by GC. The reaction results are shown in Table 2.

[0049] Table 1: Summary of experimental results of hydrocyanation of 1,3-butadiene with hydrogen cyanide

[0050] Table 2: Summary of 2M3BN isomerization experimental results

[0051] As shown in Tables 1 and 2, the [5]-helicene bidentate phosphine ligand and its catalyst prepared in this invention exhibit excellent catalytic performance, including high conversion and high selectivity, in the hydrocyanation of 1,3-butadiene and the isomerization of 2M3BN. Furthermore, the catalyst's activity remained stable after multiple reuses, demonstrating its high stability and long-lasting effect. It is noteworthy that, compared to Comparative Application Example 2, which requires the addition of Lewis acid promoters, the catalytic system of this invention achieved superior results without the use of any promoters.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bidentate phosphine ligand of the following general formula 1, which is a compound containing a spiroalkene substructure, wherein the spiroalkene substructure is the backbone of the bidentate phosphine ligand: General Formula 1 ###0001### n is an integer selected from 0 to 10; R1 is selected from phenylene, o-C1-C6 alkylphenylene, m-C1-C6 alkylphenylene, p-C1-C6 alkylphenylene, o-C1-C6 alkoxyphenylene, m-C1-C6 alkoxyphenylene, p-C1-C6 alkoxyphenylene, 1-naphthylene, 2-naphthylene, cyclohexylene, 2,4-dimethylphenyl, 2,4-di-t-butylphenyl, 2,4-dimethoxyphenyl; R2 is selected from phenyl, o-C1-C6 alkylphenyl, m-C1-C6 alkylphenyl, p-C1-C6 alkylphenyl, o-C1-C6 alkoxyphenyl, m-C1-C6 alkoxyphenyl, p-C1-C6 alkoxyphenyl, 1-naphthyl, 2-naphthyl, cyclohexyl, t-butyl, 2,4-dimethylphenyl, 2,4-di-t-butylphenyl, 2,4-dimethoxyphenyl.

2. The bidentate phosphine ligand according to claim 1, wherein n is an integer selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, preferably 1; R1 is selected from phenylene, o-methylphenylene, m-methylphenylene, p-methylphenylene, o-methoxyphenylene, m-methoxyphenylene, p-methoxyphenylene, o-ethoxyphenylene, m-ethoxyphenylene, p-ethoxyphenylene, o-propoxyphenylene, m-propoxyphenylene, p-propoxyphenylene; R2 is selected from phenyl, o-methylphenyl, m-methylphenyl, p-methylphenyl, o-methoxyphenyl, m-methoxyphenyl, p-methoxyphenyl, o-ethoxyphenyl, m-ethoxyphenyl, p-ethoxyphenyl, o-propoxyphenyl, m-propoxyphenyl, p-propoxyphenyl. wherein 3. A method for preparing the bidentate phosphine ligand according to claim 1 or 2, comprising the following two steps: Step 1: coupling reaction of compound 2 with compound 3 to obtain compound 4; Step 2: reaction of compound 5 with phosphorus trichloride for a period of time, then adding compound 4 to continue the reaction, and finally obtaining the bidentate phosphine ligand 1, wherein R1, R2 and n are defined as in claim 1 or 2; wherein the method comprises the following steps: Step 1: coupling reaction of compound 2 with compound 3 to obtain compound 4; Step 2: reaction of compound 5 with phosphorus trichloride for a period of time, then adding compound 4 to continue the reaction, and finally obtaining the bidentate phosphine ligand 1, wherein R1, R2 and n are defined as in claim 1 or 2; wherein in Step 1: the coupling reaction is carried out in an organic solvent or a mixture of organic solvent and water, in the presence of a noble metal palladium catalyst and a base, and heated to a certain temperature; the organic solvent is selected from tetrahydrofuran, toluene, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, dioxane, chloroform, dichloromethane, ethyl acetate, DMSO, N-methylpyrrolidone, or a mixture of the above solvents with water, more preferably a mixture of tetrahydrofuran and water; the volume ratio of the organic solvent to water is selected from 1:10 to 10:1, more preferably 2:1; the molar ratio of compound 2 to compound 3 is selected from 1:10 to 10:1, more preferably 1:

2.

4. The method according to claim 3, wherein the coupling reaction is carried out in a mixture of tetrahydrofuran and water, in the presence of a noble metal palladium catalyst and a base, and heated to a certain temperature. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Preferably, the noble metal palladium catalyst is selected from Pd(PPh3)4, Pd(dppf)Cl2, Pd2(dba)3, Pd(OAc)2, Pd / XPhos and Pd / SPhos system, preferably Pd(PPh3)4; Preferably, the ratio of the amount of noble metal palladium catalyst Pd(PPh3)4 to the mass of compound 2 is selected from 1%-50%, preferably 10%; Preferably, the base is mainly selected from K2CO3, Cs2CO3, Na2CO3, K3PO4, potassium tert-butoxide, sodium tert-butoxide, potassium hydroxide, sodium hydroxide, cesium fluoride, potassium fluoride, tetrabutylammonium fluoride and the like, more preferably K2CO3; Preferably, the molar ratio of the base to compound 2 is 1:10-10:1, more preferably 2:1; Preferably, the reaction temperature is 30°C-150°C, more preferably 90°C; Preferably, the reaction time is 30min-24h, more preferably 6h; In step 2: The compound 5 is first dissolved in an organic solvent, the temperature of the reaction solution is t1, then the phosphorus trichloride is added dropwise, after the dropwise addition is completed, nitrogen is introduced, and the reaction is carried out at temperature t1 for a period of time h1, then the reaction temperature is raised to t2, compound 4 is dissolved in an organic solvent and added to the reaction solution, and the reaction is continued for a period of time h2, then the temperature is raised to t3, and after reacting for a period of time h3, the final spiroalkene bidentate phosphine ligand of general formula 1 can be obtained; Preferably, the molar ratio of compound 4: compound 5: phosphorus trichloride is 1:1-50:1-50; preferably 1:4:2; Preferably, the organic solvent is an inert organic solvent, such as benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc and the like, preferably toluene; Preferably, the mass ratio of compound 4 to organic solvent is 1:0.1-50, more preferably 1:3; Preferably, the mass ratio of compound 5 to organic solvent is 1:0-50, more preferably 2:1; Preferably, the amount of nitrogen introduced is 0.01 NL / min-10 NL / min, more preferably 0.3 NL / min; Preferably, the temperature t1 is -50°C-70°C, more preferably 25°C; Preferably, the time h1 is 30min-5h, more preferably 1h; Preferably, the temperature t2 is 25°C-200°C, more preferably 50°C; Preferably, the time h2 is 30min-5h, more preferably 2h; Preferably, the temperature t3 is 5°C-200°C, more preferably 110°C; Preferably, the time h3 is 1h-24h, more preferably 12h.

4. The production method according to claim 3, characterized by, Compound 2 is prepared by the following method: The method comprises the following steps: S1: Wittig reaction of compound S1-1 and compound S1-2 to obtain compound S1-3; S2: compound S1-3 is synthesized to S1-4 by photochemical reaction; In step S1: Preferably, step S1 is carried out in the presence of an organic solvent and an amount of base: Preferably, the organic solvent is selected from benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, etc., preferably dichloromethane; Preferably, the base is selected from sodium hydroxide, potassium hydroxide, potassium tert-butoxide, sodium tert-butoxide, calcium hydroxide, ammonia, etc., preferably sodium hydroxide; Preferably, the molar ratio of compound S1-1 to compound S1-2 is 10:1-1:10, preferably 2:1; Preferably, the reaction temperature is -50°C-100°C, preferably 0°C-30°C; Preferably, the reaction time is 30 min-12 h, preferably 6 h; In step S2: Step S2 dissolves the intermediate S1-3 obtained in step S1 in an organic solvent 1, then adds an organic solvent 2 and an initiator, and obtains S1-4 under light conditions: Preferably, the organic solvent 1 is selected from benzene, toluene, chlorobenzene, chloroform, acetonitrile, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, propylene oxide, etc., more preferably toluene; Preferably, the initiator is selected from iodine, tetracyano benzene, tetracyano p-benzoquinone dimethane, dicyano benzene, 1,4-dicyanonaphthalene, 9,10-dicyanoanthracene, tetrachloro-1,4-benzoquinone, benzophenone, etc., more preferably iodine; Preferably, the organic solvent 2 is selected from benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, propylene oxide, butylene oxide, etc., more preferably propylene oxide; Preferably, the irradiation light is selected from ultraviolet light, visible light, infrared light, more preferably ultraviolet light; Preferably, the reaction temperature is 0°C-100°C, more preferably 25°C; Preferably, the reaction time is 1 day-7 days, more preferably 3 days.

5. A catalyst represented by the following formula 2, the catalyst comprising the bidentate phosphine ligand according to claim 1 or 2, and a metal atom or ion forming a coordination bond with the phosphorus atom in the aforementioned spiroalkene bidentate phosphine ligand, thereby obtaining a corresponding catalyst: Formula 2 Preferably, the metal atom or ion is selected from cobalt, nickel, platinum, ruthenium, rhodium, iridium, etc., preferably nickel.

6. A method of preparing a solution system of a catalyst according to claim 5, said method of preparing comprising: As shown in reaction formula 1, in anhydrous and anaerobic environment, in a certain organic solvent and nitrile dispersant, a large excess of metal powder or metal salt and the bidentate phosphine ligand are mixed and heated for a period of time, and then the metal powder or metal salt forms a coordination bond with the phosphorus atom in the bidentate phosphine ligand, thereby obtaining a corresponding target catalyst: Reaction formula 1 Preferably, the metal or its salt is selected from cobalt, nickel, platinum, ruthenium, rhodium, iridium metal powder or their salts, more preferably nickel or nickel salt, more preferably nickel powder; Preferably, the salt of the metal is selected from hydrochloride, nitrate, sulfate, sulfite, bisulfate, carbonate, phosphate, hydrogen phosphate, dihydrogen phosphate, acetate, etc., more preferably hydrochloride or nitrate; Preferably, the particle size of the metal nickel powder is 1-100 μm, more preferably 10-15 μm; Preferably, the mass ratio of the bidentate phosphine ligand to the metal or metal salt is selected from 1:1-50, more preferably 1:1.5-3; Preferably, the organic solvent is selected from benzene, toluene, chlorobenzene, chloroform, dichloromethane, tetrahydrofuran, dioxane, petroleum ether, n-hexane, cyclohexane, ethyl acetate, DMSO, NMP, DMF, DMAc, benzyl alcohol, etc., more preferably toluene; Preferably, the mass ratio of the bidentate phosphine ligand to the organic solvent is selected from 1:1-200, preferably 1:30; Preferably, the nitrile dispersant is selected from acetonitrile, propionitrile, acrylonitrile, benzonitrile, adiponitrile, trichloroacetonitrile, bromobenzonitrile, 3-pentenenitrile, 2-pentenenitrile, etc., more preferably 3-pentenenitrile; Preferably, the mass ratio of the bidentate phosphine ligand to the nitrile dispersant is 1:1-100, more preferably 1:10; Preferably, the reaction temperature is 50-100℃, more preferably 110℃; Preferably, the reaction time is 1-24 h, more preferably 12 h.

7. A process for the hydrocyanation of 1,3-butadiene to produce 3PN, said process comprising: In the reactor, hydrocyanic acid, 1,3-butadiene and a solution system containing the catalyst according to claim 5 are added, and the reaction is carried out under certain temperature and anhydrous and anaerobic conditions for a period of time. After the reaction is completed, 2-methyl-3-butenenitrile (2M3BN) and 3-pentenenitrile (3-PN) are obtained, and the excess olefinic substance is removed; Preferably, the molar ratio of hydrocyanic acid to the olefinic substance is selected from 1:0.1-10, preferably 1:1; Preferably, the amount of the catalyst solution system is 1%-50% of the mass of the olefinic substance, preferably 10%; Preferably, the reaction temperature is selected from 20-100℃, preferably 60℃; Preferably, the reaction time is selected from 10 min-5 h, preferably 20 min.

8. A process for the isomerization of 2M3BN to 3PN comprising: In the reactor, 2M3BN or a mixture of 2M3BN and 3PN is added, and a certain amount of a solution system containing the catalyst according to claim 5 is added, so that the reaction system is reacted under certain temperature and anhydrous and anaerobic conditions for a period of time to obtain the isomerization product 3PN; Preferably, the 2M3BN or the mixture of 2M3BN and 3PN is a reaction solution containing 95wt%-98wt% of 2M3BN raw material; Preferably, the amount of the solution system containing the catalyst according to claim 5 is 1wt%-50wt% of the mass of 2M3BN, preferably 10wt%; Preferably, the reaction temperature is 50-200℃, preferably 100-110℃; Preferably, the reaction time is 15 min-60 min, preferably 20 min-30 min.

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