Post-transition metal catalysts containing benzotriazole substituted pyridines, methods for their preparation, and their use in catalyzing the polymerization of conjugated dienes

Abstract

The application discloses a kind of post-transition metal catalysts containing benzotriazole-substituted pyridine and preparation method and its catalytic conjugated diene polymerization purposes.The application aims to synthesize a kind of post-transition metal catalyst with excellent thermal stability and high catalytic activity,And microstructure of conjugated diene can be realized simultaneously.The main catalyst is formed by coordination of benzotriazole-substituted pyridine compound and post-transition metal,Simple synthesis process,Low cost.In the absence of water and oxygen,benzotriazole-pyridine-post-transition metal complex,conjugated diene monomer and cocatalyst are added in turn,at 25-80 ℃,polymerization 5 min-24 h,after reaction,add terminator,agglomerate and dry to obtain polyconjugated diene rubber,Molecular weight and structure parameters can be adjusted.Specifically,molecular weight is 5×10 4 -500×10 4 g / mol,Molecular weight is 1.7-2.6,Conjugated diene unit cis content is 96.0%-99.9% or vinyl content is 40%-60%,Mooney viscosity (ML1+4min,100℃) is 25-90.

Description

Technical Field

[0001] This invention belongs to the field of polyconjugated diene preparation, specifically relating to a class of benzotriazole-containing conjugated diene polymerization catalysts and their preparation methods, and is used for conjugated diene polymerization. Background Technology

[0002] Synthetic rubber, especially polydiolefin rubber, plays an unparalleled role in numerous fields such as transportation and aerospace. With the rapid development of the automotive industry and the increasing awareness of safety, the demand for high-performance rubber materials is growing daily. Conjugated dienes can produce polymers with different microstructures due to different polymerization methods, such as cis (cis-1,4), trans (trans-1,4), and vinyl (3,4- or 1,2-). Among them, rubbers with high cis structure and medium vinyl content (40%-60%) exhibit excellent wear resistance, flexural strength, and grip, making them key rubber types for the preparation of high-modulus, low-consumption, and green tires. Polydiolefin rubber can be prepared by catalyst-catalyzed polymerization of dienes. Traditional catalysts for conjugated diene polymerization mainly include lithium-based catalysts, titanium-based catalysts, and rare earth catalysts. In recent years, the performance of novel homogeneous non-cyclic post-transition metal olefin polymerization catalysts in academic research and industrial applications has attracted increasing attention from scientists. Compared with traditional catalysts, post-transition metal catalysts have the characteristics of high polarity group tolerance, easily adjustable ligand space and electronic effects, and high activity, showing potential for industrial application. Furthermore, the microstructure of polydiolefins can be customized by controlling the type of transition metal and the charge and steric effects of the ligands.

[0003] Polymerization of dienes generates heat of polymerization, causing the temperature inside the reactor to rise by 10-30°C compared to the pre-designed polymerization temperature. However, most current post-transition metal catalysts suffer from poor thermal stability; at high temperatures, the coordination bonds between the ligand and the post-transition metal (such as iron or cobalt) rapidly decompose, leading to catalyst deactivation. Furthermore, the stability of the post-transition metal ligand and the relationship between it and the transition metal determines its catalytic activity, monomer conversion rate, and the microstructure of the product. Therefore, developing a novel post-transition metal ligand and catalyst that not only withstands high temperatures but also allows for the control of the microstructure (cis-structure, vinyl content) of polydiolefins is the technical problem this application aims to solve. Summary of the Invention

[0004] This invention first provides a method for synthesizing a benzotriazole-substituted pyridine compound with good thermal stability. This compound forms a diene polymerization catalyst with strong coordination ability with a later transition metal, exhibiting high-temperature tolerance. Furthermore, by controlling the electronic and steric effects of benzotriazole, as well as the type of later transition metal, it effectively regulates the microstructure (cis structure, vinyl content) of the polydiolefin. The technical solution adopted in this invention is as follows:

[0005] A class of benzotriazole-containing post-transition metal catalysts for the polymerization of conjugated dienes, characterized in that: the conjugated diene polymerization catalyst is composed of a main catalyst and a co-catalyst, wherein the main catalyst is a benzotriazole-substituted pyridine post-transition metal complex, and its structural formula is as follows.

[0006]

[0007] Preferably, the post-transition metal M is iron, cobalt, or nickel; R1 or R2 is independently selected from H, methyl, propyl, isopropyl, isobutyl, tert-butyl, bromine, phenyl, naphthyl, biphenyl, or phenyl derivatives; and X1 or X2 is independently selected from chlorine and / or bromine.

[0008] Preferably, the cocatalyst is one or more of the following: alkylaluminum halide with the general formula AlZ2Y, sesquialkylaluminum with the general formula Al2Z3Y3, alkylaluminum with the general formula AlZ3, and methylaluminoxane, wherein Z is selected from one or more of ethyl, propyl, isopropyl, isobutyl, tert-butyl, etc.; and Y is selected from chlorine or bromine.

[0009] On the other hand, the method for preparing the main catalyst for conjugated diene polymerization provided by the present invention includes the following steps:

[0010] S1. Benzotriazole, 2,6-disubstituted pyridine derivatives and organic solvents are added to a reaction apparatus and reacted at 20-200℃ for 1-24h. After cooling to room temperature, the mixture is purified to obtain benzotriazole-substituted pyridine ligands (L1).

[0011] Alternatively, benzotriazole-substituted pyridine ligand (L1), boric acid derivative, and organic solvent can be added to the reaction apparatus and reacted at 20-150℃ for 1-24h. After cooling to room temperature, the mixture can be purified to obtain benzotriazole-substituted pyridine ligand (L2).

[0012] S2. Under inert gas protection, the halogenated transition metal salt and the benzotriazole-substituted pyridine ligand obtained in S1 are dissolved in an organic solvent and added to the reaction apparatus. The reaction is carried out at 20-200℃ for 1-24 hours. After cooling to room temperature, the benzotriazole-substituted pyridine transition metal complex is obtained by purification.

[0013] Preferably, the 2,6-disubstituted pyridine derivative in step S1 has the structure shown in the following formula, wherein R' is chlorine and / or bromine, and R” is alkyl, aryl, naphthyl, cycloalkyl, halogen, etc.

[0014]

[0015] Preferably, the organic solvent in step S1 is selected from one or more of aromatic hydrocarbons and aliphatic hydrocarbons, and the organic solvent includes, but is not limited to, pentane, cyclopentane, hexane, cyclohexane, heptane, octane, tetrahydrofuran, benzene, and toluene.

[0016] Preferably, the boric acid derivative in step S1 is phenylboronic acid or 1-naphthoboronic acid.

[0017] Thirdly, the present invention provides a method for the polymerization of conjugated dienes catalyzed by substituted pyridine transition metal complexes containing benzotriazole, comprising the following steps:

[0018] S1. Under inert gas protection, add organic solvent, self-made main catalyst and conjugated diene to polymerization reactor, and heat to a constant temperature of 30℃-100℃.

[0019] S2. Add a co-catalyst to initiate the polymerization reaction of conjugated dienes for 30 min to 6 h.

[0020] S3. Add a terminator to the polymerization reaction solution to terminate the polymerization. Coagulate and dry to obtain conjugated diene rubber.

[0021] Preferably, the conjugated diene in step S1 is one or more of butadiene, isoprene, and 1,3-pentadiene.

[0022] Preferably, the organic solvent in step S1 is selected from one or more of nonpolar aromatic hydrocarbons and nonpolar aliphatic hydrocarbons, and the organic solvent includes, but is not limited to, pentane, cyclopentane, hexane, cyclohexane, heptane, octane, benzene, and toluene.

[0023] Preferably, the cocatalyst in step S2 is one or more of the following: alkylaluminum halide with the general formula AlR2X, sesquialkylaluminum with the general formula Al2R3X3, alkylaluminum with the general formula AlR3, and methylaluminoxane, wherein R is one or more of the following: ethyl, propyl, isopropyl, isobutyl, tert-butyl, etc.

[0024] Preferably, the molar ratio of the main catalyst to the co-catalyst is 1:10 to 1000.

[0025] Preferably, the conjugated diene rubber includes, but is not limited to, one or more of C4-C6 conjugated dienes (preferably butadiene, isoprene, or a mixture thereof).

[0026] Preferably, the terminator in step S3 consists of an acidified alcohol compound containing an active hydrogen atom and an antioxidant. Examples include an ethanol solution acidified with hydrochloric acid and 2,6-di-tert-butyl-4-methylphenol, an ethanol solution acidified with hydrochloric acid and N-isopropyl-N'-phenyl-p-phenylenediamine, a methanol solution acidified with hydrochloric acid and styrene-modified phenol, and an isopropanol solution acidified with hydrochloric acid and pentaerythritol diisodecyl diphosphite.

[0027] Preferably, the number-average molecular weight of the conjugated diene rubber is in the range of 5 × 10⁻⁶. 4 —500×10 4 g / mol, molecular weight distribution range of 1.7-2.6, cis content of conjugated diene unit of 96.0%-99.9% or vinyl content of 40%-60%, Mooney viscosity (ML1+4min, 100℃) of 25-90.

[0028] The significant advantages of this invention compared to existing technologies are:

[0029] The benzotriazole-substituted pyridine ligand synthesized in this invention has a simple preparation process and is stable in air and at high temperatures. It readily forms stable complexes with subsequent transition metals, especially iron and cobalt. The resulting benzotriazole-substituted pyridine post-transition metal catalyst exhibits high reactivity towards conjugated dienes under the activation of a co-catalyst. Furthermore, by varying the electronic and steric effects of the benzotriazole-substituted pyridine ligand and the type of transition metal, polyconjugated diene products with a predominantly cis-structure and / or moderate vinyl content microstructure were obtained. The cis-predominant polyconjugated diene exhibits good flexibility, imparting high wear resistance and low frictional heat generation to the material, and shows high reactivity with vulcanizing agents. The formed cross-linked network ensures the strength of the polyconjugated diene structure; the moderate vinyl structure ensures high anti-skid performance, showing excellent application prospects in the preparation of tire tread compounds. Attached Figure Description

[0030] Figure 1 The image shows the crystal structure of the Fe1 catalyst synthesized in Example 6, obtained by single-crystal diffractometer.

[0031] Figures 2-6 The chemical structures of the main catalyst ligands prepared in Examples 1-5 are shown in sequence. 1 H NMR and 13 C NMR spectrum.

[0032] Figure 7The NMR spectrum of the polyisoprene rubber prepared in Example 16 is shown.

[0033] Figure 8 The infrared spectrum of the polybutadiene rubber prepared in Example 17 is shown.

[0034] Figure 9 The infrared spectrum of the polybutadiene isoprene rubber prepared in Example 18 is shown.

[0035] Figure 10 The infrared spectrum of the polyisoprene rubber prepared in Example 19 is shown.

[0036] Figure 11 The infrared spectrum of the polyisoprene rubber prepared in Example 20 is shown.

[0037] Figure 12 The infrared spectrum of the polybutadiene prepared in Example 22 is shown. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0039] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0040] Example 1: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand (L1) according to the following steps:

[0041] Benzotriazole (10.0 g, 63.2 mmol) and 2-bromopyridine (15.2 g, 126.4 mmol) were dissolved in 50 mL of toluene and refluxed for 18 h. After cooling to room temperature, the solution was poured into 200 mL of ethyl acetate, and 30 mL of 10% KOH solution was added. The organic phase was washed twice with 50 mL of KOH solution, dried over anhydrous sodium sulfate, filtered, and concentrated to obtain the crude product. The target product was recrystallized in methanol to give benzotriazole-substituted pyridine ligand L1 in 95% yield. 1 H NMR (400MHz, CDCl3) δ8.62(dd,J=20.0,6.1Hz,2H),8.29(d,J=8.3Hz,1H),8.11(d,J=8.3Hz,1H ),7.96–7.84(m,1H),7.59(t,J=7.7Hz,1H),7.44(t,J=7.6Hz,1H),7.30(dd,J=7.2,5.0Hz,1H). 13C NMR (176MHz, CDCl3) δ 151.1, 146.7, 140.8, 140.0, 131.2, 129.3, 126.1, 125.2, 119.9, 114.7, 112.566, 77.2, 77.0, 76.8. Structure of ligand L1 and... 1 H NMR and 13 C NMR characterization as follows Figure 2 As shown.

[0042] Example 2: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand (L2) according to the following steps:

[0043] Benzotriazole (0.952 g, 8.0 mmol) and 2-bromo-6-methylpyridine (0.688 g, 4.0 mmol) were added to a 100 mL Schlenk flask, and the mixture was reacted at 200 °C for 30 min. After cooling to room temperature, water and dichloroethane were added, and the mixture was extracted three times with dichloroethane. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated to obtain the crude product. The crude product was purified by column chromatography using ethyl acetate and petroleum ether as eluents to obtain the benzotriazole-substituted pyridine ligand L2. The yield was 86%. 1 H NMR (400MHz, CDCl3) δ8.69 (d, J=8.4Hz, 1H), 8.11 (dd, J=12.6, 8.3Hz, 2H), 7.83 (t, J=7.9 Hz,1H),7.61(t,J=7.6Hz,1H),7.46(t,J=7.6Hz,1H),7.19(d,J=7.5Hz,1H),2.69(s,3H). 13 CNMR (101MHz, CDCl3) δ 157.8, 151.1, 146.6, 139.1, 131.6, 128.7, 124.9, 121.7, 119.7, 115.1, 111.3, 24.2. L2 ligand structure and... 1 H NMR and 13 C NMR characterization as follows Figure 3 As shown.

[0044] Example 3: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand (L3) according to the following steps:

[0045] Benzotriazole (7.14 g, 60 mmol) and 2,6-dibromopyridine (9.48 g, 60 mmol) were added to a 100 mL Schlenk flask. The mixture was reacted at 180 °C for 3 h. After cooling to room temperature, 100 mL of dichloromethane was added. The insoluble residue was filtered off, and the solvent was removed to obtain the crude product. The crude product was purified by column chromatography using petroleum ether and ethyl acetate as eluents to obtain the benzotriazole-substituted pyridine ligand L3. The yield was 75%. 1 H NMR (400MHz, CDCl3) δ8.59(d,J=8.4Hz,1H),8.27(d,J=8.1Hz,1H),8.12(d,J =8.3Hz,1H),7.78(t,J=7.9Hz,1H),7.64(t,J=7.7Hz,1H),7.57–7.40(m,2H). 13 C NMR (101MHz, CDCl3) δ 151.1, 146.8, 146.8, 140.859, 140.0, 131.3, 129.3, 126.2, 125.3, 119.9, 114.7, 112.6. The structure of ligand L3 and... 1 H NMR and 13 C NMR characterization as follows Figure 4 As shown.

[0046] Example 4: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand (L4) according to the following steps:

[0047] Ligand L3 (1.65 g, 6.0 mmol), phenylboronic acid (1.02 g, 8.4 mmol), cesium carbonate (3.12 g, 9.6 mmol), and Pd(PPh3)4 were dissolved in 40 mL of tetrahydrofuran. The mixture was refluxed at 50 °C for 24 h. After cooling to room temperature, water and dichloromethane were added, and the mixture was extracted three times with dichloromethane. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The crude product was purified by column chromatography using petroleum ether and ethyl acetate as eluents to give benzotriazole-substituted pyridine ligand L4. The yield was 83%. 1 H NMR (400MHz, CDCl3) δ8.79(d,J=8.3Hz,1H),8.25(d,J=8.0Hz,1H),8.14(dd,J=19.8,8.1H z,3H),8.00(t,J=7.8Hz,1H),7.76(d,J=7.7Hz,1H),7.70–7.61(m,1H),7.60–7.40(m,4H). 13C NMR (101MHz, CDCl3) δ 156.6, 151.5, 139.7, 138.4, 131.7, 129.6, 129.0, 128.8, 127.0, 124.9, 119.8, 118.7, 114.8, 112.7. L4 ligand structure and... 1 H NMR and 13 C NMR characterization as follows Figure 5 As shown.

[0048] Example 5: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand (L5) according to the following steps:

[0049] Ligand L3 (1.65 g, 6.0 mmol), 1-naphthoboric acid (1.44 g, 8.4 mmol), cesium carbonate (3.12 g, 9.6 mmol), and Pd(PPh3)4 were dissolved in 40 mL of 1,4-dioxane. The mixture was refluxed for 6 h, cooled to room temperature, and then water and dichloromethane were added, followed by three extractions with dichloromethane. The organic phase was dried over anhydrous magnesium sulfate, filtered, and concentrated. The crude product was purified by column chromatography using petroleum ether and ethyl acetate as eluents to give benzotriazole-substituted pyridine ligand L5. The yield was 93%. 1 H NMR (400MHz, CDCl3) δ8.60(d,J=7.4Hz,1H),8.41(d,J=8.3Hz,1H),8.31(d,J=8.5Hz,1H),8.20–8.05(m, 2H), 8.00 (t, J=8.0Hz, 2H), 7.75 (dd, J=7.1, 1.1Hz, 1H), 7.65 (dd, J=4.5, 3.9Hz, 2H), 7.61–7.36 (m, 4H). 13 C NMR (101MHz, CDCl3) δ 158.2, 151.4, 146.8, 139.4, 137.4, 134.0, 131.6, 131.0, 129.4, 128.9, 128.5, 127.8, 126.6, 126.2, 125.6, 125.3, 64, 124.9, 123.3, 119.7, 115.3, 112.4. The structure of ligand L5 and... 1 H NMR and 13 C NMR characterization as follows Figure 6 As shown.

[0050] Example 6: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand iron complex (Fe1) according to the following steps:

[0051] Under a nitrogen atmosphere, FeCl2 (0.254 g, 2 mmol) was dissolved in 40 mL of anhydrous ethanol, and the temperature was raised to 60 °C until FeCl2 was completely dissolved. An ethanol solution of ligand L1 (0.392 g, 2 mmol) was added dropwise to the FeCl2 ethanol solution, and the reaction was carried out at 60 °C for 4 h. The solution was cooled to room temperature and incubated overnight at -20 °C. The precipitated solid was filtered and dried to constant weight in a vacuum drying oven at 40 °C to obtain the benzotriazole-substituted pyridine ligand iron complex (Fe1). Yield: 70%. ESI-MS: Theoretical value: m / z = 518.0224, Measured value: 481.0577 [M-Cl]+. The crystal structure information of the catalyst Fe1 is as follows: Figure 1 As shown.

[0052] Example 7: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand iron complex (Fe2) according to the following steps:

[0053] Under an argon atmosphere, FeCl2 (0.065 g, 0.5 mmol) and ligand L2 (0.252 g, 1.2 mmol) were added to a 100 mL Schlenk flask, followed by 50 mL of toluene. The mixture was heated to 120 °C and refluxed for 24 h. After cooling to room temperature, the precipitate was filtered, washed with toluene, and dried to constant weight in a vacuum oven at 40 °C to obtain the benzotriazole-substituted pyridine ligand iron complex (Fe2). Yield: 72%. ESI-MS: Theoretical value: m / z = 546.0537, Measured value: 509.0890 [M-Cl]+.

[0054] Example 8: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand iron complex (Fe3) according to the following steps:

[0055] Under a nitrogen atmosphere, FeCl2 (0.065 g, 0.5 mmol) and ligand L3 were added to a 100 mL Schlenk flask, followed by 50 mL of toluene. The mixture was refluxed for 1 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, then dried to constant weight in a vacuum oven at 40 °C to obtain the benzotriazole-substituted pyridine ligand iron complex (Fe3). Yield: 69%. ESI-MS: Theoretical value: m / z = 675.8414, Measured value: 636.8787 [M-Cl]+.

[0056] Example 9: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand iron complex (Fe4) according to the following steps:

[0057] Under an argon atmosphere, FeCl2 (0.065 g, 0.5 mmol) and ligand L4 were added to a 100 mL Schlenk flask, followed by 50 mL of toluene. The mixture was refluxed for 12 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, then dried to constant weight in a vacuum oven at 40 °C to obtain the benzotriazole-substituted pyridine ligand iron complex (Fe4). Yield: 64%. ESI-MS: Theoretical value: m / z = 670.0850, Measured value: 634.1166 [M-Cl]+.

[0058] Example 10: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand iron complex (Fe5) according to the following steps:

[0059] Under a nitrogen atmosphere, FeCl2 (0.065 g, 0.5 mmol) and ligand L5 were added to a 100 mL Schlenk flask, followed by 50 mL of toluene. The mixture was refluxed for 15 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, then dried to constant weight in a vacuum oven at 40 °C to obtain the benzotriazole-substituted pyridine ligand iron complex (Fe5). Yield: 62%. ESI-MS: Theoretical value: m / z = 770.1163, Measured value: 733.1581 [M-Cl]+.

[0060] Example 11: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand cobalt complex (Co1) according to the following steps:

[0061] Under a nitrogen atmosphere, CoCl2 (0.260 g, 2 mmol) and 40 mL of tetrahydrofuran were added to a Schlenk flask and stirred until completely dissolved. Then, a tetrahydrofuran solution of ligand L1 (0.392 g, 2 mmol) was added dropwise. The mixture was stirred overnight at 20 °C. The precipitate was filtered and washed with tetrahydrofuran. It was dried to constant weight in a vacuum drying oven at 40 °C, yield 73%. ESI-MS: Theoretical value: m / z = 522.2592, Measured value: 486.0513 [M-Cl]+.

[0062] Example 12: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand cobalt complex (Co2) according to the following steps:

[0063] Under a nitrogen atmosphere, CoCl2 (0.065 g, 0.5 mmol) and 40 mL of toluene were added to a Schlenk flask, stirred at 110 °C for 1 h, and L2 (0.252 g, 1.2 mmol) of toluene solution was added dropwise, followed by reflux for 8 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, then dried to constant weight in a vacuum drying oven at 50 °C, yield 71%. ESI-MS: Theoretical value: m / z = 550.3132, Measured value: 514.0826 [M-Cl]+.

[0064] Example 13: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand cobalt complex (Co3) according to the following steps:

[0065] Under a nitrogen atmosphere, CoCl2 (0.065 g, 0.5 mmol) and 40 mL of toluene were added to a Schlenk flask, stirred at 110 °C for 1 h, and L3 of toluene solution was added dropwise, followed by reflux for 10 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, then dried to constant weight in a vacuum drying oven at 50 °C, yield 69%. ESI-MS: Theoretical value: m / z = 680.0512, Measured value: 643.8718 [M-Cl]+.

[0066] Example 14: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand cobalt complex (Co4) according to the following steps:

[0067] Under a nitrogen atmosphere, CoCl2 (0.065 g, 0.5 mmol) and 40 mL of toluene were added to a Schlenk flask, stirred at 110 °C for 1 h, and then L4 of toluene solution was added dropwise, followed by reflux for 9 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, and dried to constant weight in a vacuum drying oven at 50 °C, with a yield of 65%. ESI-MS: Theoretical value: m / z = 674.4552, Measured value: 638.1160 [M-Cl]+.

[0068] Example 15: This example provides a method for synthesizing a benzotriazole-substituted pyridine ligand cobalt complex (Co5) according to the following steps:

[0069] Under a nitrogen atmosphere, CoCl2 (0.065 g, 0.5 mmol) and 40 mL of toluene were added to a Schlenk flask, stirred at 110 °C for 1 h, and then L5 of toluene solution was added dropwise, followed by reflux for 12 h. After cooling to room temperature, the precipitate was filtered and washed with toluene, and dried to constant weight in a vacuum drying oven at 50 °C, with a yield of 67%. ESI-MS: Theoretical value: m / z = 774.5752, Measured value: 738.1436 [M-Cl]+.

[0070] Example 16: This example provides a method for the polymerization of isoprene catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0071] Under an argon atmosphere, toluene, isoprene (Ip), and benzotriazole-substituted pyridine ligand iron complex (Fe1) were added sequentially to a polymerization flask at a molar ratio of Fe1 to Ip of 1:5000 and a temperature of 25°C. Methylaluminoxane (MAO) was added and reacted for 6 hours at a molar ratio of MAO to Fe1 of 100. The polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. The polymer was then coagulated, dried, and polyisoprene rubber was obtained. The yield was >99%, the number-average molecular weight was 2300 kg / mol, the molecular weight distribution was 1.72, the cis content was 56.9%, the vinyl content was 43.1%, and the Mooney viscosity was 58.

[0072] Example 17: This example provides a method for butadiene polymerization catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0073] Under an argon atmosphere, n-hexane, butadiene (Bd), and benzotriazole-substituted pyridine ligand iron complex (Fe1) were added sequentially to a polymerization flask at a molar ratio of Fe1 to Bd of 1:3000 and a temperature of 70°C. Methylaluminoxane (MAO) was added and reacted for 6 hours at a molar ratio of MAO to Fe1 of 100. The polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. The polymer was then coagulated, dried, and polybutadiene rubber was obtained. The yield was >99%, the number-average molecular weight was 5000 kg / mol, the molecular weight distribution was 2.02, the cis content was 41.4%, the vinyl content was 58.6%, and the Mooney viscosity was 88.

[0074] Example 18: This example provides a method for copolymerizing butadiene and isoprene catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0075] Under an argon atmosphere, toluene, butadiene (Bd), isoprene (Ip), and benzotriazole-substituted pyridine ligand iron complex (Fe1) were added sequentially to a polymerization flask. The molar ratio of Fe1 to (Bd+Ip) was 1:4000, and the temperature was 80℃. Methylaluminoxane (MAO) was added and reacted for 2 hours, with a molar ratio of MAO to Fe1 of 200. The polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. After coagulation and drying, polybutadiene-isoprene rubber was obtained. The yield was >99%, the number-average molecular weight was 2800 kg / mol, the molecular weight distribution was 2.02, the cis content was 53.9%, the vinyl content was 46.1%, and the Mooney viscosity was 63.

[0076] Example 19: This example provides a method for the polymerization of isoprene catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0077] Under an argon atmosphere, toluene, isoprene (Ip), and benzotriazole-substituted pyridine ligand iron complex (Fe2) were added sequentially to a polymerization flask at a molar ratio of Fe2 to Ip of 1:6000 and a temperature of 70°C. Methylaluminoxane (MAO) was added and reacted for 5 hours at a molar ratio of MAO to Fe2 of 100. The polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. The polymer was then coagulated, dried, and polyisoprene rubber was obtained. The yield was 92%, the number-average molecular weight was 1200 kg / mol, the molecular weight distribution was 1.96, the cis content was 59.9%, the vinyl content was 40.1%, and the Mooney viscosity was 55.

[0078] Example 20: This example provides a method for the polymerization of isoprene catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0079] Under an argon atmosphere, toluene, isoprene (Ip), and benzotriazole-substituted pyridine ligand iron complex (Fe1) were added sequentially to a polymerization flask. The molar ratio of Fe1 to Ip was 1:5000, and the temperature was 25°C. Triisobutylaluminum (Al) was then added. i Bu3) reacted for 1 hour, Al i The molar ratio of Bu3 to Fe1 was 20. Polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. The polymer was then coagulated, dried, and polyisoprene rubber was obtained. The yield was 89%, the number-average molecular weight was 300 kg / mol, the molecular weight distribution was 2.59, the cis content was 59.9%, the vinyl content was 40.1%, and the Mooney viscosity was 49.

[0080] Example 21: This example provides a method for the polymerization of isoprene catalyzed by benzotriazole-substituted pyridine ligand iron complexes, which is carried out according to the following steps:

[0081] Under an argon atmosphere, toluene, isoprene (Ip), and benzotriazole-substituted pyridine ligand iron complex (Fe1) were added sequentially to a polymerization flask at a molar ratio of Fe1 to Ip of 1:3000 and a temperature of 50°C. After Fe1 was completely dissolved, methylaluminoxane (MAO) was added and reacted for 6 hours at a molar ratio of MAO to Fe1 of 1000. Ethanol was added to terminate the polymerization, and the mixture was allowed to coagulate and dry to obtain polyisoprene rubber. The yield was >99%, the number-average molecular weight was 50 kg / mol, the molecular weight distribution was 2.02, the cis content was 58.9%, the vinyl content was 41.1%, and the Mooney viscosity was 25.

[0082] Example 22: This example provides a method for butadiene polymerization catalyzed by a benzotriazole-substituted pyridine ligand cobalt complex, which is carried out according to the following steps:

[0083] Under an argon atmosphere, toluene, butadiene (Bd), and a benzotriazole-substituted pyridine ligand cobalt complex (Co1) were added sequentially to a polymerization flask at a molar ratio of Co1 to Bd of 1:2000, at a temperature of 70°C. Ethyl aluminum chloride (Al2Et3Cl3) was added and reacted for 4 hours, with a molar ratio of Al2Et3Cl3 to Co1 of 10. The polymerization was terminated by adding an ethanol solution containing 1.0 wt% 2,6-di-tert-butyl-4-methylphenol and 5% hydrochloric acid. The polymer was then coagulated, dried, and polybutadiene rubber was obtained. The yield was 90%, the number-average molecular weight was 950 kg / mol, the molecular weight distribution was 2.58, the cis content was 98.1%, and the Mooney viscosity was 53.

[0084] Example 23: This example provides a method for butadiene polymerization catalyzed by a benzotriazole-substituted pyridine ligand cobalt complex, which is carried out according to the following steps:

[0085] Under an argon atmosphere, toluene, butadiene (Bd), and a benzotriazole-substituted pyridine ligand cobalt complex (Co1) were added sequentially to a polymerization flask at a molar ratio of Co1 to Bd of 1:2000 and a temperature of 100°C. Methylaluminoxane (MAO) was then added and reacted for 1 hour at a molar ratio of MAO to Co1 of 300. The polymerization was terminated by adding ethanol, followed by coagulation and drying to obtain polybutadiene rubber. The yield was 93%, the number-average molecular weight was 96 kg / mol, the molecular weight distribution was 2.01, the cis content was 96.5%, and the Mooney viscosity was 28.

[0086] Example 24: This example provides a method for butadiene polymerization catalyzed by a benzotriazole-substituted pyridine ligand cobalt complex, which is carried out according to the following steps:

[0087] Under an argon atmosphere, toluene, butadiene (Bd), and a benzotriazole-substituted pyridine ligand cobalt complex (Co5) were added sequentially to a polymerization flask at a molar ratio of Co5 to Bd of 1:2000 and a temperature of 50°C. Methylaluminoxane (MAO) was added and reacted for 4 hours at a molar ratio of MAO to Co5 of 300. The polymerization was terminated by adding ethanol, followed by coagulation and drying to obtain polybutadiene rubber. The yield was 93%, the number-average molecular weight was 50 kg / mol, the molecular weight distribution was 2.05, the cis content was 97.5%, and the Mooney viscosity was 24.9.

[0088] It can be seen that the benzotriazole-substituted pyridine post-transition metal catalyst synthesized by the technical solution of the present invention has a stable structure. On the one hand, it exhibits high catalytic activity over a wide temperature range (20-100℃), covering the industrial polymerization temperature and polymerization temperature rise of diolefins (the industrial polymerization temperature of polydiolefins is usually 50℃, and the polymerization temperature rise is about 20℃). On the other hand, the microstructure (high cis and medium vinyl) of polyconjugated dienes can be customized by varying the electronic and steric effects of the ligands.

[0089] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A class of benzotriazole-containing post-transition metal catalysts for the polymerization of conjugated dienes, characterized in that: The conjugated diene polymerization catalyst consists of a main catalyst and a co-catalyst. The main catalyst is a transition metal complex of benzotriazole-substituted pyridine, and its structural formula I is as follows: Ⅰ Wherein, M is selected from iron, cobalt, and nickel; R1 or R2 is independently selected from H, methyl, propyl, isopropyl, isobutyl, tert-butyl, bromine, phenyl, naphthyl, and biphenyl; X1 or X2 is independently selected from chlorine or bromine. The cocatalyst is one or more of the following: alkyl aluminum halide with the general formula AlZ2Y, sesquialkyl aluminum halide with the general formula Al2Z3Y3, alkyl aluminum halide with the general formula AlZ3, and methylaluminoxane, wherein Z is selected from one or more of ethyl, propyl, isopropyl, isobutyl, and tert-butyl; and Y is selected from chlorine or bromine.

2. A method for preparing the catalyst according to claim 1, characterized in that: Includes the following steps: S1: Benzotriazole, a 2,6-disubstituted pyridine derivative, and an organic solvent are added to a reaction apparatus and reacted at 50-200℃ for 0.5-24h. After cooling to room temperature, the mixture is purified to obtain benzotriazole-substituted pyridine ligand L1. The 2,6-disubstituted pyridine derivative has the structure shown in II below, wherein R' is chlorine and / or bromine, and R” is alkyl, aryl, naphthyl, cycloalkyl, or halogen. Ⅱ Alternatively, benzotriazole-substituted pyridine ligand L1, boric acid derivative, and organic solvent can be added to a reaction apparatus and reacted at 20-200℃ for 1-24 hours. After cooling to room temperature, the mixture can be purified to obtain benzotriazole-substituted pyridine ligand L2. The boric acid derivative is phenylboronic acid or 1-naphthoboronic acid. S2: Under inert gas protection, the halogenated transition metal salt and the benzotriazole-substituted pyridine ligand L1 or L2 obtained in S1 are dissolved in an organic solvent, added to the reaction apparatus, and reacted at 20-120℃ for 1-24 h to obtain the benzotriazole-substituted pyridine transition metal complex.

3. The preparation method according to claim 2, characterized in that: The organic solvent is selected from one or more of aromatic hydrocarbons and aliphatic hydrocarbons.

4. The preparation method according to claim 2, characterized in that: The organic solvent is selected from tetrahydrofuran.

5. The preparation method according to claim 3, characterized in that: The organic solvents include, but are not limited to, pentane, cyclopentane, hexane, cyclohexane, heptane, octane, benzene, and toluene.

6. A method for polymerizing conjugated dienes catalyzed by the catalyst of claim 1, characterized in that: Includes the following steps: S1. Under inert gas protection, add organic solvent, main catalyst and conjugated diene to polymerization reactor, and heat to a constant temperature of 25℃-100℃; S2. Add a co-catalyst to initiate the polymerization reaction of conjugated dienes for 5 min–6 h; S3. Add a terminator to the polymerization reaction solution to terminate the polymerization. Coagulate and dry to obtain conjugated diene rubber.

7. The method according to claim 6, characterized in that: The conjugated diene in step S1 is selected from one or more of butadiene, isoprene, and 1,3-pentadiene; The organic solvent in step S1 is selected from one or more of nonpolar aromatic hydrocarbons and nonpolar aliphatic hydrocarbons.

8. The method according to claim 6, characterized in that: The organic solvents include, but are not limited to, pentane, cyclopentane, hexane, cyclohexane, heptane, octane, benzene, and toluene.

9. The method according to claim 6, characterized in that: The molar ratio of the main catalyst to the co-catalyst is 1:10~1000.

10. The method according to claim 6, characterized in that... The conjugated diene rubber is a homopolymer or copolymer of conjugated dienes.

11. The method according to claim 6, characterized in that... The conjugated diene rubber has a number-average molecular weight range of 5 × 10⁻⁶. 4 —500×10 4 g / mol, molecular weight distribution range of 1.7-2.6, cis content of conjugated diene unit of 96.0%-99.9% or vinyl content of 40%-60%, Mooney viscosity ML1+4 min, 25-90 at 100 °C.

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