A ligand for polyketone resin polymerization catalyst and its preparation method and application

Abstract

The present invention provides a ligand for a polyketone resin polymerization catalyst, a preparation method, and an application thereof. The ligand of the polyketone resin polymerization catalyst of the present invention is 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane, whose structural formula is shown in formula (I). The preparation method thereof comprises the following steps: (1) chlorinating 1,1-cyclopropane dimethanol with a chlorinating agent to obtain 1,1-dichloromethylcyclopropane; (2) subjecting 1,1-dichloromethylcyclopropane to a substitution reaction with bis(2-methoxyphenyl)phosphine in the presence of a base to obtain 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane. The ligand provided by the present invention is used for the production of polyketone using a palladium-based catalyst. Compared with existing catalytic systems, it can obtain a higher polymerization reaction rate, higher catalyst efficiency, higher thermal stability, and can be stored for a longer period of time while maintaining catalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of catalysts, in particular to a ligand of a polyketone resin polymerization catalyst and a preparation method and application thereof. Background Art

[0002] Polyketone is an engineering plastic whose molecular backbone is composed of carbon and hydrogen, forming a tightly crystalline structure through high crystallization. As a new green polymer material synthesized from carbon monoxide and olefins (ethylene and propylene), it exhibits high impact strength, with the impact strength of PBT being 230% higher than that of Nylon. Polyketone's wear resistance is 14 times that of POM. Its hydrocarbon barrier properties are comparable to those of EVOH in terms of gas barrier performance, and its chemical resistance makes it stable in acids and alkalis (except for strong acids and bases). Its strain capacity, recoverability, and balance of toughness and rigidity are all superior to other engineering plastics such as POM and PA66. Because polyketone's synthetic raw materials include carbon monoxide, a major source of air pollution, and some grades are biodegradable, it is a new green polymer material with broad development prospects in terms of energy conservation and environmental friendliness.

[0003] Polymerization catalysts used to prepare polyketones typically consist of a Pd(II) / bidentate phosphine ligand / acid system. Bisphosphine ligands with high catalytic activity include 1,3-bis[bis(2-methoxyphenyl)phosphino]propane, ((2,2-dimethyl-1,3-dioxane-5,5-diyl)bis(methylene))bis(bis(2-methoxykolamyl)phosphine), and 3,3-bis-[bis-(2-methoxyphenyl)phosphinomethyl]-1,5-dioxa-spiro[5,5]undecane. These ligands suffer from low activity, poor thermal stability, and complex synthesis. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a ligand for a polyketone resin polymerization catalyst and a preparation method and application thereof, so as to solve the problems of low ligand activity, poor thermal stability and complex synthesis of polyketone resin polymerization catalysts in the prior art.

[0005] To achieve the above-mentioned and other related purposes, the present invention adopts the following technical solutions:

[0006] The first aspect of the present invention provides a ligand for a polyketone resin polymerization catalyst, wherein the ligand is 1,1-bis[di(2-methoxyphenyl)phosphinomethyl]cyclopropane, and its structural formula is shown in the following formula (I):

[0007]

[0008] A second aspect of the present invention provides a method for preparing the ligand of the polyketone resin polymerization catalyst, comprising the following steps:

[0009] (1) 1,1-cyclopropane dimethanol is subjected to a chlorination reaction with a chlorination reagent to obtain 1,1-dichloromethylcyclopropane;

[0010] (2) 1,1-dichloromethylcyclopropane is reacted with bis(2-methoxyphenyl)phosphine in the presence of a base to obtain 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane.

[0011] The third aspect of the present invention provides use of the ligand of the polyketone resin polymerization catalyst in the preparation of polyketone resin.

[0012] A fourth aspect of the present invention provides a polyketone resin polymerization catalyst comprising a metal palladium catalyst, trifluoroacetic acid, and a ligand of the polyketone resin polymerization catalyst.

[0013] A fifth aspect of the present invention provides use of the polyketone resin polymerization catalyst in the preparation of a polyketone resin.

[0014] As described above, the ligand of the polyketone resin polymerization catalyst and the synthesis method thereof of the present invention have the following beneficial effects:

[0015] 1. The ligand of the polyketone resin polymerization catalyst provided by the present invention is a new bidentate phosphine ligand, which is used for the production of polyketone using a palladium-based catalyst. Compared with existing catalytic systems, the bidentate phosphine ligand catalytic system of the present invention is used for polymerization reaction to synthesize polyketone, which can obtain a higher polymerization reaction rate and a higher catalyst efficiency (kg polyketone / g palladium). At the same time, it has higher thermal stability than other catalytic systems and can be stored for a longer time while maintaining catalytic activity.

[0016] 2. The present invention provides a method for preparing a ligand for a polyketone resin polymerization catalyst. The synthetic raw material uses 1,1-cyclopropane dimethanol, which is lower in cost and more readily available. A novel bidentate phosphine ligand can be obtained through a two-step reaction of chlorination and substitution. This method has lower cost, more convenient reaction, and has prospects for industrial application. DETAILED DESCRIPTION

[0017] The ligand of the polyketone resin polymerization catalyst of the present invention, its preparation method and application are described in detail below.

[0018] The first aspect of the present invention provides a ligand for a polyketone resin polymerization catalyst, wherein the ligand is 1,1-bis[di(2-methoxyphenyl)phosphinomethyl]cyclopropane, and its structural formula is shown in the following formula (I):

[0019]

[0020] 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane, with a molecular weight of 558.2. Since the two phosphines of the bisphosphine ligand maintain a stable conformation away from each other due to steric hindrance when not coordinated, when coordinated with Pd, the huge steric hindrance of the methoxyphenyl group deteriorates the thermal stability of the complex. When a rigid steric hindrance is added at a position two Cs away from P, the tendency of the two Ps to move away from each other due to the steric hindrance of the substituents can be suppressed, thereby improving the stability of the coordination structure. The 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane ligand provided by the present invention has a three-membered ring in the structural formula, which can achieve a better balanced steric effect due to its large ring rigidity, while minimizing the damage to stability. Therefore, compared with other ligand catalytic systems, it has higher thermal stability.

[0021] A second aspect of the present invention provides a method for preparing the ligand of the polyketone resin polymerization catalyst, comprising the following steps:

[0022] (1) 1,1-cyclopropane dimethanol is subjected to a chlorination reaction with a chlorination reagent to obtain 1,1-dichloromethylcyclopropane;

[0023] (2) 1,1-dichloromethylcyclopropane is reacted with bis(2-methoxyphenyl)phosphine in the presence of a base to obtain 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane.

[0024] In some embodiments of the present invention, in step (1), the chlorination agent is sulfonyl chloride. Preferably, the molar ratio of the sulfonyl chloride to the 1,1-cyclopropane dimethanol is 0.5 to 1.5:1, can be 0.5 to 1:1, or can be 1 to 1.5:1.

[0025] In some embodiments of the present invention, in step (1), the chlorination reaction is carried out in an organic solvent; the organic solvent is selected from dichloromethane or dichloroethane.

[0026] In some embodiments of the present invention, in step (1), the chlorination agent is diluted with a solvent and then added dropwise to the reaction system. Preferably, the solvent used for dilution is the same as the solvent of the reaction system.

[0027] In some embodiments of the present invention, in step (1), the temperature of the chlorination reaction is 0-40°C, which can be 0-5°C, 5-10°C, 10-15°C, 15-20°C, 20-25°C, 25-30°C, 30-35°C, or 35-40°C; preferably 20-25°C.

[0028] In some embodiments of the present invention, in step (1), the chlorination reaction time is 1 to 2 hours, can be 1 to 1.5 hours, or can be 1.5 to 2 hours; preferably 1.5 hours.

[0029] In some embodiments of the present invention, in step (1), after the reaction is completed, water is added for quenching; after quenching, the water in the reaction solution is usually separated.

[0030] In some embodiments of the present invention, step (1) further comprises washing the reaction product to remove water and solvent. Preferably, the washing medium is an alkaline aqueous solution selected from an aqueous potassium carbonate solution, an aqueous sodium carbonate solution, an aqueous ammonium chloride solution, an aqueous sodium hydroxide solution, or an aqueous potassium hydroxide solution, preferably an aqueous sodium carbonate solution; preferably, the method for removing water and solvent is vacuum distillation, preferably rotary distillation.

[0031] In some embodiments of the present invention, in step (2), the substitution reaction is carried out in an anhydrous and oxygen-free environment.

[0032] In some embodiments of the present invention, in step (2), the substitution reaction is carried out in an organic solvent; the organic solvent is an aprotic polar solvent, preferably, the organic solvent is N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP) or sulfolane.

[0033] In some embodiments of the present invention, in step (2), the base is selected from sodium tert-butoxide. Preferably, the molar ratio of the sodium tert-butoxide to the bis(2-methoxyphenyl)phosphine is 2 to 3.5:1, and may be 2 to 2.5:1, 2.5 to 3:1, or 3 to 3.5:1.

[0034] In some embodiments of the present invention, in step (2), the molar ratio of bis(2-methoxyphenyl)phosphine to 1,1-bischloromethylcyclopropane is 1.5-2:1, and can be 1.5-1.6:1, 1.6-1.7:1, 1.7-1.8:1, 1.8-1.9:1, or 1.9-2:1.

[0035] In some embodiments of the present invention, in step (2), the temperature of the substitution reaction is 45-80°C, which can be 45-50°C, 50-55°C, 55-60°C, 60-65°C, 65-70°C, 70-75°C, or 75-80°C.

[0036] In some embodiments of the present invention, in step (2), the substitution reaction time is 2 to 6 hours, which can be 2 to 2.5 hours, 2.5 to 3 hours, 3 to 3.5 hours, 3.5 to 4 hours, 4 to 4.5 hours, 4.5 to 5 hours, 5 to 5.5 hours, or even 5.5 to 6 hours.

[0037] In some embodiments of the present invention, in step (2), after the reaction is completed, the process further comprises extraction, washing, drying, concentration and purification. Preferably, the extractant for the extraction is water and an organic solvent; further preferably, the organic solvent used as the extractant is selected from any one or more of dichloromethane, dichloroethane, ethyl acetate, methyl acetate, toluene and xylene. In some specific embodiments of the present invention, the washing medium is a 30% to 60% methanol aqueous solution; in some specific embodiments of the present invention, the drying temperature is 60 to 120°C, which may be 60 to 70°C, 70 to 80°C, 80 to 90°C, 90 to 100°C, 100 to 110°C, or 110 to 120°C; the drying time is 5 to 30 minutes, which may be 5 to 10 minutes, 10 to 15 minutes, 15 to 20 minutes, 20 to 25 minutes, or 25 to 30 minutes; in some specific embodiments of the present invention, the purification comprises recrystallization and drying, and preferably, the solvent used for the recrystallization is methanol.

[0038] The third aspect of the present invention provides use of the ligand of the polyketone resin polymerization catalyst in the preparation of polyketone resin.

[0039] A fourth aspect of the present invention provides a polyketone resin polymerization catalyst comprising a metal palladium catalyst, trifluoroacetic acid, and a ligand for the polyketone resin polymerization catalyst. In some embodiments of the present invention, the metal palladium catalyst is palladium acetate. Preferably, the molar ratio of the palladium acetate catalyst to the ligand 1,1-bis[di(2-methoxyphenyl)phosphinomethyl]cyclopropane is 0.5 to 1.5:1, can be 0.5 to 1:1, can be 1 to 1.5:1, and is preferably 0.85:1.

[0040] The fifth aspect of the present invention provides the use of the above-mentioned polyketone resin polymerization catalyst in the preparation of polyketone resin. The ligand catalyst system provided by the present invention has a higher catalytic efficiency than existing ligand catalyst systems and can be relatively stable and maintain catalytic activity.

[0041] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] Below in conjunction with preferred embodiment, the specific embodiment of the present invention is described in further detail.When embodiment provides numerical range, it should be understood that, unless otherwise specified in the present invention, the two endpoints of each numerical range and any numerical value between the two endpoints can be selected.Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those generally understood by those skilled in the art.Except the specific method, equipment, material used in the embodiment, as those skilled in the art grasp the prior art and record of the present invention, any method, equipment and material of the prior art similar or equivalent to the method, equipment, material in the embodiments of the present invention can also be used to realize the present invention.

[0043] Example 1

[0044] This embodiment provides a method for preparing a ligand of a polyketone resin polymerization catalyst, using 1,1-cyclopropane dimethanol as a starting material, and obtaining a target product through a two-step reaction of chlorination and substitution, as shown in the following reaction formula:

[0045]

[0046] The specific steps include:

[0047] Step 1: Dissolve 5.10g of 1,1-cyclopropane dimethanol (0.05mol) in 150mL of dichloromethane. Take 14.8g of sulfonyl chloride (0.11mol) and add it to 75mL of dichloromethane, dilute it 5-fold, and then slowly add it to the reaction. During the addition, control the temperature below 40°C in a water bath. Stir the reaction for 1.5 hours, then slowly add water to quench the reaction. Separate the water from the reaction solution, wash the organic phase again with sodium carbonate aqueous solution, and spin dry to obtain the oily product 1,1-dichloromethylcyclopropane (6.6g, 95% yield);

[0048] Step 2: Under anhydrous and oxygen-free conditions, 4.8 g (1.5 eq, 0.015 mol) of bis(2-methoxyphenyl)phosphine was dissolved in 20 g of DMF, and 3.4 g (3.5 eq, 0.035 mol) of sodium tert-butoxide was added and stirred for 30 minutes to complete the reaction. 1.4 g (0.01 mol) of 1,1-dichloromethylcyclopropane was dissolved in 40 mL of DMF and slowly added dropwise to the reaction solution. After stirring for 30 minutes, the temperature was raised to 60°C and the reaction was allowed to proceed for 4 hours. After completion of the reaction, the solvent was recovered by distillation under reduced pressure, and water and an organic solvent were added for extraction. The organic phase was collected, washed, dried, and concentrated to obtain a crude product. The crude product was recrystallized, and the solid was collected and dried to obtain the target product, 1,1-bis[di(2-methoxyphenyl)phosphinomethyl]cyclopropane (pale yellow solid, 5.1 g, 91% yield).

[0049] 1HNMR(CDCl3): 7.29-7.15(m, 8H), 6.87-6.75(m, 8H), 3.7(s, 12H), 2.42(s, 4H), 0.3(s, 4H);

[0050] 31 P NMR (DMSO): -45.67 ppm.

[0051] Example 2

[0052] This embodiment provides a method for preparing a polyketone resin polymerization catalyst, which specifically comprises the following steps:

[0053] S1. Dissolve 21 mg of palladium acetate in 20 mL of acetone, add 0.11 mmol of the ligand prepared in Example 1, and stir at 25°C to dissolve.

[0054] S2. Add 75 μL of trifluoroacetic acid and stir for 1 hour to obtain a polyketone resin polymerization catalyst (in solution form).

[0055] Example 3

[0056] This embodiment provides a method for preparing a polyketone resin, which specifically comprises the following steps:

[0057] 200 mL of methanol and 1.2 mL of the polyketone resin polymerization catalyst prepared in Example 2 were added to a 250 mL reactor, and 9.5 g of polyketone finished product powder was added as seeds. The reactor was replaced with nitrogen 5 times, and then the temperature was raised to 90 ° C. A mixture of carbon monoxide and ethylene (molar ratio of 1: 1) was introduced to make the pressure in the reactor reach 53 bar, and the reaction lasted for 7 hours. Finally, the reaction was terminated by cooling and pressure relief. The obtained polyketone powder 1 (excluding 9.5 g seeds) was collected, the molecular weight was measured, and the catalytic efficiency 1 was calculated.

[0058] Stability test: A polyketone resin polymerization catalyst (solution form) was prepared by the same preparation method as in Example 2. After the obtained catalyst was allowed to stand for one day and one night, a polyketone resin was prepared by the same preparation method as in Example 3 using the polyketone resin polymerization catalyst. The obtained polyketone powder (excluding 9.5 g of seeds) was collected, the molecular weight was measured, and the catalytic efficiency 2 was calculated.

[0059] Comparative Example 1

[0060] In this comparative example, 9 different catalyst ligands were prepared.

[0061] (1) Using the bromide represented by formula A as a raw material, ligand 1-5 was prepared by the following reaction:

[0062]

[0063] Wherein, according to the different groups R1, the brominated raw materials represented by formula A are shown in the following Table 1.

[0064] Table 1 Preparation of ligands 1 to 5 Brominated compounds represented by formula A

[0065] A Ligand 1 1,3-Dibromopropane Ligand 2 1,3-Dibromo-2,2-dimethylpropane Ligand 3 1,1-Bis(bromoethyl)cyclohexane Ligand 4 1,1-Bis(bromoethyl)cycloheptane Ligand 5 Bis(bromomethyl)ether

[0066] Under anhydrous and oxygen-free conditions, 1.0 g of bis(2-methoxyphenyl)phosphine was dissolved in 11 g of DMF in a water bath at room temperature to yield a colorless, transparent liquid. 0.5 g of sodium tert-butoxide was added and stirred continuously for one hour. Under anhydrous and oxygen-free conditions, 2.6 mmol of the brominated starting material represented by Formula A was dissolved in 5.3 g of DMF at room temperature and slowly added dropwise to the reaction solution. The temperature was maintained between 20 and 25°C throughout the reaction. After stirring for 30 minutes, the temperature was raised to 60°C and the reaction was allowed to proceed for 4 hours. 10 mL of water and 10 mL of toluene were added to the reaction mixture for extraction. After stirring and allowing the mixture to stand, the upper toluene phase was collected and washed several times with water. Anhydrous sodium sulfate was then added to dry the mixture. The toluene solution was then distilled under reduced pressure to recover the toluene, yielding a crude product. Methanol was added to azeotropically evaporate the toluene, which was then dried and cooled to yield a solid product, namely, ligand 1-5.

[0067] (2) Using the ketone compound represented by formula B as a raw material, ligand 6-9 was prepared by the following reaction:

[0068]

[0069]

[0070] Among them, according to the difference of group R2, the ketone compound represented by formula B and the bromide represented by formula C are shown in Table 2 below.

[0071] Table 2 Preparation of Ligands 6 to 9 Ketone compounds represented by Formula B and bromides represented by Formula C

[0072] B C Ligand 6 Cyclohexanone 3,3-Bis(bromoethyl)-1,5-dioxazolospiro[5.5]undecane Ligand 7 Cyclododecanone 3,3-Bis(bromoethyl)-1,5-dioxazolospiro[5.11]heptadecane Ligand 8 acetone 5,5-Bis(bromoethyl)-2,2-dimethyl-1,3-dioxolane Ligand 9 3-Pentanone 5,5-Bis(bromoethyl)-2,2-diethyl-1,3-dioxolane

[0073] Under a nitrogen atmosphere, 2,2-(bromomethyl)propane-1,3-diol (1 g, 3.8 mmol) was dissolved in 15 g of dichloromethane. 5.7 mmol of the ketone compound raw material represented by formula B was added to the mixture and cooled until the internal temperature reached 0 to 5°C. While maintaining the internal temperature, 0.1 g of concentrated sulfuric acid was added, and then the mixture was stirred at an internal temperature of 0 to 5°C for 2 hours. The obtained mixture was washed twice with an aqueous solution containing sodium bicarbonate, then washed with water, and then dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure to obtain the intermediate brominated compound represented by formula C. The intermediate brominated compound represented by formula C was dissolved in DMF solvent, and then reacted and purified according to the preparation method of ligand 1-5 to obtain ligand 6-9.

[0074] Ligand 1: {3-[bis(2-methoxyphenyl)phosphino]propyl}bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.24-7.17(m, 8H), 6.85-6.71(m, 8H), 3.72(s, 12H), 2.51(d, 4H), 1.34(s, 2H);

[0075] Ligand 2: {3-[bis(2-methoxyphenyl)phosphino]-2,2-dimethylpropyl}bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.23-7.16(m, 8H), 6.81-6.73(m, 8H), 3.70(s, 12H), 2.53(d, 4H), 1.25(s, 6H);

[0076] Ligand 3: [(1-{[bis(2-methoxyphenyl)phosphino]methyl}cyclohexyl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.28-7.14(m, 8H), 6.84-6.71(m, 8H), 3.72(s, 12H), 2.53(d, 4H), 1.24(s, 10H);

[0077] Ligand 4: [(1-{[bis(2-methoxyphenyl)phosphino]methyl}cycloheptyl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.23-7.14(m, 8H), 6.81-6.72(m, 8H), 3.70(s, 12H), 2.55(d, 4H), 1.25(s, 12H);

[0078] Ligand 5: ({[bis(2-methoxyphenyl)phosphino]methoxy}methyl)bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.23-7.16(m, 8H), 6.81-6.73(m, 8H), 3.91(d, 4H), 3.70(s, 12H);

[0079] Ligand 6: [(3-{[bis(2-methoxyphenyl)phosphino]methyl}-1,5-dioxaspiro[5.5]undec-3-yl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.23-7.26(m, 8H), 6.85-6.85(m, 8H), 3.92(s, 4H), 3.72(s, 12H), 2.54(d, 4H), 1.44(s, 4H), 1.22(s, 6H);

[0080] Ligand 7: [(3-{[bis(2-methoxyphenyl)phosphino]methyl}-1,5-dioxaspiro[5.11]heptadecan-3-yl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.26-7.16(m, 8H), 6.87-6.75(m, 8H), 3.72(s, 4H), 3.70(s, 12H), 2.51(d, 4H), 1.21-1.36(m, 18H);

[0081] Ligand 8: [(5-{[bis(2-methoxyphenyl)phosphino]methyl}-2,2-dimethyl-1,3-dioxan-5-yl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR(CDCl3): 7.26-7.16(m, 8H), 6.87-6.75(m, 8H), 3.92(s, 4H), 3.70(s, 12H), 2.51(d, 4H), 1.44(s, 6H);

[0082] Ligand 9: [(5-{[bis(2-methoxyphenyl)phosphino]methyl}-2,2-diethyl-1,3-dioxan-5-yl)methyl]bis(2-methoxyphenyl)phosphine; 1 HNMR (CDCl3): 7.26-7.16 (m, 8H), 6.87-6.75 (m, 8H), 3.92 (s, 4H), 3.70 (s, 12H), 2.51 (d, 4H), 1.43 (s, 4H), 1.28 (s, 6H).

[0083] Comparative Example 2

[0084] This comparative example adopts the same operation as Example 2, except that the ligand prepared in Example 1 is replaced by 9 different catalyst ligands prepared in Comparative Example 1, thereby preparing 9 catalysts.

[0085] Comparative Example 3

[0086] This comparative example adopts the same operation as Example 3, except that the 9 catalysts prepared in Comparative Example 2 are used instead of the polyketone resin polymerization catalyst prepared in Example 2, and the obtained polyketone powder 1 (excluding 9.5g seeds) is collected, the molecular weight is measured and the catalytic efficiency 1 is calculated.

[0087] Stability test: The 9 different catalyst ligands prepared in Comparative Example 1 were respectively used to prepare catalysts (in solution form) using the same preparation method as in Comparative Example 2. After the obtained catalysts were allowed to stand for one day and one night, the same preparation method as in Example 3 was used to prepare polyketone resin as a polyketone catalyst. The obtained polyketone powder (excluding 9.5 g of seeds) was collected, the molecular weight was measured, and the catalytic efficiency 2 was calculated.

[0088] The polyketone resins, catalytic efficiencies and stability obtained in the above examples and comparative examples are shown in Table 3 below.

[0089] Table 3 Polyketone resins, catalytic efficiency and stability obtained in Examples and Comparative Examples

[0090]

[0091] As shown in Table 3, increasing the steric hindrance of the phosphine ligand bridge structure results in limited improvement in catalytic efficiency and a rapid decrease in catalyst stability. Only bridge structures with moderate steric hindrance can simultaneously enhance catalytic efficiency and maintain catalytic activity. This is because, when uncoordinated, the two phosphines of the bisphosphine ligand maintain a stable, mutually distant conformation due to steric hindrance. Upon coordination with Pd, the significant steric hindrance of the methoxyphenyl group degrades the thermal stability of the complex. Adding a rigid steric hindrance at a position two carbon atoms away from the P can suppress the tendency of the two P atoms to move away from each other due to steric hindrance from the substituents, thereby improving the stability of the coordination structure. Because the distance between the substituents in the bridge structure and a P is smaller than the distance between P atoms, excessive steric hindrance from the bridge structure causes the ligand to change its conformation to achieve chelation coordination with Pd, hindering the steric hindrance of the substituted group, making the coordination structure unstable and prone to decomposition. The trend of decreased thermal stability is less pronounced when the substituents added to the central bridge structure are 3- to 6-membered rings. Among the various ligands, the three-membered ring, due to its greater ring rigidity, can provide a better balance of steric hindrance while minimizing the impact on stability. Furthermore, the raw materials for the three-membered ring are more readily available than those for the four-membered or even six-membered rings, offering good economic benefits.

[0092] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0093] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A ligand for a polyketone resin polymerization catalyst, characterized in that: The ligand is 1,1-bis[di(2-methoxyphenyl)phosphinomethyl]cyclopropane, and its structural formula is shown in the following formula (I): （Ⅰ）。 2. A method for preparing a ligand for a polyketone resin polymerization catalyst according to claim 1, characterized in that: The steps include: (1) 1,1-cyclopropane dimethanol is subjected to chlorination reaction with a chlorination reagent to obtain 1,1-dichloromethylcyclopropane; (2) 1,1-Dichloromethylcyclopropane is reacted with bis(2-methoxyphenyl)phosphine in the presence of a base to obtain 1,1-bis[bis(2-methoxyphenyl)phosphinomethyl]cyclopropane.

3. The method for preparing a ligand of a polyketone resin polymerization catalyst according to claim 2, wherein: In step (1), one or more of the following features are included: (1a) The chlorination agent is sulfonyl chloride; (1b) the chlorination reaction is carried out in an organic solvent; (1c) the chlorination reagent is diluted with a solvent and added dropwise to the reaction system; (1d) The temperature of the chlorination reaction is 0-40°C; (1e) The chlorination reaction time is 1 to 2 hours; (1f) After the reaction is completed, water is added for quenching; (1g) also includes washing the reaction product and removing water and solvent.

4. The preparation method according to claim 3, characterized in that In step (1), one or more of the following features are included: (1a1) the molar ratio of the sulfonyl chloride to the 1,1-cyclopropane dimethanol is 0.5 to 1.5:1; (1b1) the organic solvent is selected from dichloromethane or dichloroethane; (1c1) The solvent used for dilution is the same as that used in the reaction system; (1g1) The washing medium used is an alkaline aqueous solution; (1g2) The method for removing water and solvent is distillation under reduced pressure.

5. The method for preparing a ligand of a polyketone resin polymerization catalyst according to claim 2, wherein: In step (2), one or more of the following features are included: (2a) The substitution reaction is carried out in an anhydrous and oxygen-free environment; (2b) The substitution reaction is carried out in an organic solvent; (2c) the base is selected from sodium tert-butoxide; (2d) The molar ratio of bis(2-methoxyphenyl)phosphine to 1,1-bischloromethylcyclopropane is 1.5 to 2:1; (2d) The temperature of the substitution reaction is 45-80°C; (2e) The substitution reaction time is 2 to 6 hours; (2f) After the reaction is completed, it also includes extraction, washing, drying, concentration and purification.

6. The method for preparing a ligand of a polyketone resin polymerization catalyst according to claim 5, wherein: In step (2), one or more of the following features are included: (2b1) The organic solvent is selected from any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl-2-pyrrolidone, and sulfolane; (2c1) The molar ratio of the sodium tert-butoxide to the bis(2-methoxyphenyl)phosphine is 2 to 3.5:1; (2f1) The extraction solvent is water and an organic solvent; (2f2) The washing medium is water; (2f3) The drying temperature is 60-120°C and the drying time is 5-30 minutes; (2f4) The purification includes recrystallization and drying.

7. The method for preparing a ligand of a polyketone resin polymerization catalyst according to claim 6, wherein: In step (2), one or more of the following features are included: (2f11) The organic solvent used as the extractant is selected from one or more combinations of dichloromethane, dichloroethane, ethyl acetate, methyl acetate, toluene, and xylene; (2f41) The solvent used for the recrystallization is methanol.

8. Use of the ligand of the polyketone resin polymerization catalyst according to claim 1 in the preparation of polyketone resin.

9. A polyketone resin polymerization catalyst, characterized in that The invention comprises a metal palladium catalyst, trifluoroacetic acid and a ligand of the polyketone resin polymerization catalyst as claimed in claim 1.

10. Use of the polyketone resin polymerization catalyst according to claim 9 in the preparation of polyketone resin.

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