CN114249849B - Highly branched iron-based conjugated diene polymer and preparation method thereof - Google Patents

Abstract

The invention provides a highly branched iron-based conjugated diene polymer and a preparation method thereof, belonging to the field of conjugated diene catalytic polymerization. In the iron-based conjugated diene polymer provided by the invention, the 3,4-(1,2-) structure accounts for 60% to 80%, and the 1,4 structure accounts for 20% to 40%. Gel content <1% and glass transition temperature ‑80°C‑10°C. The present invention significantly improves the solubility of the iron complex in the reaction solvent by changing the anions in the iron complex. The modified aluminum reagent obtained by reacting the modifier with the alkyl aluminum, when paired with the iron complex, has excellent Compared with the existing technology, the reaction activity avoids the use of necessary dealkylation reagents in the alkyl aluminum system, reduces the process flow, reduces the reaction cost, and provides important technical support for the industrial production of iron-based rubber. The resulting conjugated diene polymer has the characteristics of high branching, low gel content or even no gel, and low glass transition temperature, which significantly improves product quality and performance.

Description

Highly branched iron-based conjugated diene polymer and preparation method thereof

Technical Field

The invention belongs to the field of conjugated diene catalytic polymerization, and specifically relates to a highly branched iron-based conjugated diene polymer and a preparation method thereof.

Background Art

Artificially synthesized highly branched polyconjugated diene is an ideal rubber material for high-performance environmentally friendly tires. It has excellent anti-skid performance, low rolling resistance, low compression heat generation and high anti-aging performance. Therefore, it is increasingly favored by the rubber industry. When highly branched butyl-pentene rubber is used as a tire support rubber, it can significantly improve the tire's anti-skid performance and greatly reduce the compression heat generation of the tire without increasing the tire's rolling resistance. It is called "China's potential eighth type of synthetic rubber" by the Synthetic Rubber Industry Association and has great application prospects in high-performance tires such as aviation tires and ship silencing and noise reduction materials. In the transition metal-catalyzed conjugated diene polymerization system, iron-based catalysts have been widely studied due to their low toxicity, low price, rich content, and unique catalytic effect.

Wang Fusong's research group prepared polyisoprene with high 3.4-structure content, but the gel content of the polymer was high, up to 10%, which affected the processing performance of the product. Moreover, the system reacts in aromatic solvents at low temperatures, and the reaction toxicity is high, which does not meet the production requirements of green chemistry. Giovanni Ricci et al. used a bidentate ligand/FeCl ₂ /MAO catalytic system to prepare highly branched isoprene polymers, but there are few reports on the iron-catalyzed copolymerization of isoprene and butadiene. In this catalytic system, the catalyst reacts in the form of a suspension, and poor solubility will lead to difficulties in continuous production and feeding, and the use of MAO aluminum reagents is costly, so it does not meet the requirements of industrial production. Therefore, there are still great limitations in promoting the industrial production of highly branched polyconjugated dienes.

Summary of the invention

The invention provides a highly branched iron-based conjugated diene polymer and a preparation method thereof. A cheap, efficient, and well-solubility bipyridine iron complex/modified aluminum catalyst system is used to prepare an iron-based conjugated diene polymer with a high content of 3,4-structure, a low gel content, and a low glass transition temperature.

In order to solve the above technical problems, the present invention provides an iron-based conjugated diene polymer, in which the proportion of 3,4-(1,2-) structure is 60% to 80%, the proportion of 1,4 structure is 20% to 40%, the gel content is <1% and the glass transition temperature is -80°C to 10°C.

Preferably, the iron-based conjugated diene polymer has a number average molecular weight of 100,000 to 800,000 and a molecular weight distribution of 1.0 to 5.0.

The present invention also provides a method for preparing an iron-based conjugated diene polymer, comprising the following steps:

In an argon atmosphere, a bipyridine iron complex and a modified aluminum catalyst system, a conjugated diene monomer and a solvent are added into a reactor to form a reaction system, and a polymerization reaction is carried out at 0°C to 90°C with stirring for 10min to 30min. After the reaction, a quencher and an anti-aging agent are added, and the mixture is washed and dried to obtain an iron-based conjugated diene polymer.

Preferably, the bipyridine iron complex is prepared by the following method:

In an argon atmosphere, an equimolar amount of an N,N-bidentate electron-rich compound and an organic iron compound are added to an anhydrous reaction solvent, and stirred at 0 to 60° C. for 1 to 36 hours to obtain a bipyridine iron complex having the following general structural formula:

Preferably, the N,N-bidentate electron-rich compound is selected from one of the following structures:

Preferably, the organic iron compound Fe(X) _n is selected from at least one of ferrous acetylacetonate, ferrous naphthenate, ferrous isooctanoate, ferrous neodecanoate, ferrous acetylacetonate, ferrous acetate, ferrous caproate, ferrous stearate and ferrous octanoate.

Preferably, the anhydrous reaction solvent is selected from at least one of aliphatic saturated hydrocarbons, aromatic hydrocarbons, aromatic halides and cycloalkanes.

Preferably, the anhydrous reaction solvent is selected from at least one of cyclohexane, n-hexane, ethanol, dichloromethane, dichloropropane, toluene and chlorobenzene.

Preferably, the reaction temperature is 20-40° C., and the reaction time is 1-12 h.

Preferably, the modified aluminum is prepared by the following method:

Under an argon atmosphere, add the modifier to the organoaluminum compound, stir and react at -10°C to 30°C for 1 min to 1 h to obtain modified aluminum.

Preferably, the organoaluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, triisopropylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, dimethylaluminum chloride, diethylaluminum hydride, diisobutylaluminum hydride and dimethylaluminum hydride.

Preferably, the modifier is selected from at least one of water, cardanol, phenol, cresol, naphthol, nitrophenol, 2,6-di-tert-butyl-p-cresol, 2,6-di-tert-butylphenol, p-tert-butylcatechol, methanol, ethanol, propanol, n-octanol, isooctyl alcohol, n-hexanol, tert-butanol, triphenylmethanol, benzyl alcohol, formic acid, acetic acid, isooctyl acid, benzoic acid, stearic acid, cyclopentyl acid and neodecanoic acid.

Preferably, the molar ratio of the organic aluminum compound to the modifier in the modified aluminum is 1:(0.01-2).

Preferably, the conjugated diene compound is selected from at least one of isoprene and butadiene.

Preferably, when the conjugated diene compound is a mixture of isoprene and butadiene, the proportion of isoprene is 1% to 99%.

Preferably, the solvent is a non-polar solvent or a polar/non-polar mixed solvent, wherein the non-polar solvent is selected from at least one of cyclohexane, n-hexane, n-heptane, petroleum ether, benzene, toluene, and xylene, and the polar solvent is selected from at least one of tetrahydrofuran, acetone, acetonitrile, pyridine, and chlorobenzene.

Preferably, in the polar/non-polar mixed solvent, the concentration of the polar solvent is 0 ppm to 400 ppm.

Preferably, the molar ratio of the conjugated diene monomer to the iron element in the bipyridine iron complex is (1000-20000):1, preferably 5000:1.

Preferably, the molar ratio of the aluminum element in the modified aluminum to the iron element in the bipyridine iron complex is (10-100):1, preferably 40:1.

Preferably, the volume ratio of the conjugated diene monomer to the solvent is 1:(1-20), preferably 1:5.

Preferably, the reaction temperature is 40-70° C., and the reaction time is 30 min.

Preferably, the quencher is a mixed solution of concentrated hydrochloric acid and methanol, wherein the volume ratio of methanol to concentrated hydrochloric acid is 50:1; and the volume ratio of the quencher to the solvent is 1:2.5.

Preferably, the volume ratio of the anti-aging agent to the solvent is 1:25, and the anti-aging agent is an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a mass concentration of 1%.

Compared with the prior art, the present invention has the following significant effects:

The conjugated diene polymer obtained by the present invention has the characteristics of high content of 3,4-structure, stable molecular weight and wide molecular weight distribution range, low gel content and glass transition temperature, which is conducive to improving its processing performance;

The present invention aims to solve the problem that the iron-based catalyst has poor solubility and the process is complicated when performing heterogeneous polymerization reaction. The inorganic anions in the iron-based catalyst are replaced with suitable organic anions, which significantly improves its solubility, thereby performing the reaction in a homogeneous polymerization system and optimizing its production process.

The present invention aims at the problem of high cost of the entire industrial production when a conventional MAO two-component system and a three-component system including a dealkylation agent are used in the existing iron-based conjugated diene polymerization process. A universal and cheaper alkyl aluminum reagent is selected to modify the system, so that the reaction system can achieve a significant reduction in cost while still having a reaction activity comparable to that of conventional two-component and conventional three-component catalyst systems, that is, most polymerization reaction yields can reach >90% within 30 minutes.

The present invention adjusts the structure of the N,N-bidentate electron-rich compound in the bipyridine iron complex and coordinates it with different organic iron compounds to form bipyridine iron complexes with different catalytic characteristics. The synergistic effect of the N,N-bidentate electron-rich compound ligand and the organic iron anion can be used to effectively change its electronic effect and the electrical properties of the metal center, affect the polymerization reaction speed and heat release rate, and thus achieve the effect of significantly reducing the gel content in the conjugated diene polymer.

The bipyridine iron complex/modified aluminum catalyst system designed by the present invention is different from the existing conjugated diene catalyst system. It has good tolerance to polar functional groups, and the introduction of some THF into the system does not affect the reaction yield. In addition, the presence of polar compounds has a stabilizing effect on the active center of the catalyst system, thereby improving the thermal stability of the reaction system. Under the premise of ensuring the reaction yield, the optimal reaction temperature of the system can be increased from 50°C to 60°C, making the production of iron-based conjugated diene polymers universal, and providing a design idea for the preparation of multifunctional iron-based rubbers;

6. The bipyridine iron complex/modified aluminum catalytic reaction system of the present invention has the characteristics of excellent solubility, high reaction activity, low reaction cost and high temperature resistance, which provides important technical support for the industrial production of iron-based rubber; the obtained conjugated diene polymer has the characteristics of high branching, low gel content or even no gel and low glass transition temperature, which significantly improves the product quality and performance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a hydrogen spectrum of the polymer obtained in Example 28 provided by the present invention;

FIG2 is a carbon spectrum of the polymer obtained in Example 28 provided by the present invention;

FIG3 is a GPC of the polymer obtained in Example 28 provided by the present invention;

FIG4 is a gel test of the polymer obtained in Example 28 provided by the present invention;

FIG5 is a DSC graph of the polymer obtained in Example 45 provided by the present invention;

FIG6 is a DSC graph of the polymer obtained in Example 53 provided by the present invention;

FIG7 is a DSC graph of the polymer obtained in Example 54 provided by the present invention;

FIG8 is a solubility comparison diagram of catalysts 1, 2, 13, and 14 provided by the present invention and ferric chloride catalysts.

DETAILED DESCRIPTION

Example 1: The structural formula of the bipyridine iron complex (catalyst 1) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(2-EHA) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L1 into it in sequence, stir and react at room temperature for 1 hour to obtain a brown-yellow liquid, i.e., the bipyridine iron complex solution.

Mass spectrum analysis: C ₃₄ H ₅₃ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 641.3253; found value: 641.3257.

Elemental analysis: C ₃₄ H ₅₃ FeN ₂ O ₆ : Theoretical value: C, 63.64%; H, 8.33%; N, 4.37%; Found value: C, 63.59%; H, 8.37%; N, 4.33%.

Example 2: The structural formula of the bipyridine iron complex (catalyst 2) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(2-EHA) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L2 into it in sequence, stir and react at room temperature for 1 hour to obtain a brown-yellow liquid, i.e., the bipyridine iron complex solution.

Mass spectrum analysis: C ₃₆ H ₅₃ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 665.3253; found value: 665.3256.

Elemental analysis: C ₃₆ H ₅₃ FeN ₂ O ₆ : Theoretical value: C, 64.96%; H, 8.03%; N, 4.21%; Found value: C, 64.93%; H, 8.09%; N, 4.27%.

Example 3: The structural formula of the bipyridine iron complex (catalyst 3) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(2-EHA) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L3 into it in sequence, stir and react at room temperature for 1 hour to obtain a brown-yellow liquid, i.e., the bipyridine iron complex solution.

Mass spectrum analysis: C ₃₆ H ₅₇ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 669.3566; found value: 669.3571.

Elemental analysis: C ₃₆ H ₅₇ FeN ₂ O ₆ : Theoretical value: C, 64.57%; H, 8.58%; N, 4.18%; Found value: C, 64.63%; H, 8.52%; N, 4.23%.

Example 4: The structural formula of the bipyridine iron complex (catalyst 4) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(2-EHA) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L4 into it in sequence, stir and react at room temperature for 1 hour to obtain a brown-yellow liquid, i.e., the bipyridine iron complex solution.

Mass spectrum analysis: C ₃₆ H ₅₇ FeN ₂ O ₆ : [M+H] ⁺ : theoretical value: 669.3566; found value: 669.3568.

Elemental analysis: C ₃₆ H ₅₇ FeN ₂ O ₆ : Theoretical value: C, 64.57%; H, 8.58%; N, 4.18%; Found value: C, 64.61%; H, 8.63%; N, 4.21%.

Example 5: The structural formula of the bipyridine iron complex (catalyst 5) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(Naph) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L1 into it in sequence, stir and react at room temperature for 1 hour to obtain a brown-yellow liquid, i.e., the bipyridine iron complex solution.

Mass spectrum analysis: C ₃₂ H ₂₂ FeN ₂ O ₄ : [M+H] ⁺ : theoretical value: 554.0929; found value: 554.0933.

Elemental analysis: C ₃₂ H ₂₂ FeN ₂ O ₄ : Theoretical value: C, 69.33%; H, 4.00%; N, 5.05%; Found value: C, 69.37%; H, 4.11%; N, 5.13%.

Example 6: The structural formula of the bipyridine iron complex (catalyst 6) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(Naph) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L2 thereto in sequence, stir and react at room temperature for 1 h to obtain a brown-yellow liquid, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₃₄ H ₂₂ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 578.0929; found value: 578.0934.

Elemental analysis: C ₃₄ H ₂₂ FeN ₂ O ₄ : Theoretical value: C, 70.60%; H, 3.83%; N, 4.84%; Found value: C, 70.55%; H, 3.87%; N, 4.79%.

Example 7: The structural formula of the bipyridine iron complex (catalyst 7) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(Naph) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L3 thereto in sequence, stir and react at room temperature for 1 h to obtain a brown-yellow liquid, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₃₄ H ₂₆ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 582.1242; found value: 582.1247.

Elemental analysis: C ₃₄ H ₂₆ FeN ₂ O ₄ : Theoretical value: C, 70.11%; H, 4.50%; N, 4.81%; Found value: C, 70.17%; H, 4.46%; N, 4.88%.

Example 8: The structural formula of the bipyridine iron complex (catalyst 8) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(Naph) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L4 thereto in sequence, stir and react at room temperature for 1 h to obtain a brown-yellow liquid, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₃₄ H ₂₆ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 582.1242; found value: 582.1245.

Elemental analysis: C ₃₄ H ₂₆ FeN ₂ O ₄ : Theoretical value: C, 70.11%; H, 4.50%; N, 4.81%; Found value: C, 70.19%; H, 4.53%; N, 4.73%.

Example 9: The structural formula of the bipyridine iron complex (catalyst 9) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L1 thereto in sequence, stir the reaction at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a brown-yellow solid product, i.e., a bipyridine iron complex solution.

Mass spectrometry analysis: C ₂₀ H ₂₂ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 411.1002; found value: 410.0999.

Elemental analysis: C ₂₀ H ₂₂ FeN ₂ O ₄ : Theoretical value: C, 58.55%; H, 5.41%; N, 6.83%; Measured value: C, 58.43%; H, 5.51%; N, 7.02%.

Example 10: The structural formula of the bipyridine iron complex (catalyst 10) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L2 thereto in sequence, stir the reaction at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₂ H ₂₂ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 435.1002; found value: 435.1007.

Elemental analysis: C ₂₂ H ₂₂ FeN ₂ O ₄ : Theoretical value: C, 60.85%; H, 5.11%; N, 6.45%; Found value: C, 61.03%; H, 5.31%; N, 6.61%.

Example 11: The structural formula of bipyridine-bipyridine iron complex (catalyst 11) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₂ and 0.2 mmol N,N-bidentate electron-rich compound L3 thereto in sequence, stir and react at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₂ H ₂₆ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 439.1315; found value: 439.1319.

Elemental analysis: C ₂₂ H ₂₆ FeN ₂ O ₄ : Theoretical value: C, 60.29%; H, 5.98%; N, 6.39%; Found value: C, 59.97%; H, 5.72%; N, 6.54%.

Example 12: The structural formula of bipyridine-bipyridine iron complex (catalyst 12) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L4 thereto in sequence, stir and react at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₂ H ₂₆ FeN ₂ O _4: [M+H] ⁺ : theoretical value: 439.1315; found value: 439.1317.

Elemental analysis: C ₂₂ H ₂₆ FeN ₂ O ₄ : Theoretical value: C, 60.29%; H, 5.98%; N, 6.39%; Found value: C, 60.18%; H, 6.11%; N, 6.46%.

Example 13: The structural formula of bipyridine-bipyridine iron complex (catalyst 13) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L1 thereto in sequence, stir the reaction at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₅ H ₂₉ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 510.1448; found value: 510.1451.

Elemental analysis: C ₂₅ H ₂₉ FeN ₂ O ₆ : Theoretical value: C, 58.95%; H, 5.74%; N, 5.50%; Found value: C, 58.71%; H, 5.67%; N, 5.65%.

Example 14: The structural formula of bipyridine-bipyridine iron complex (catalyst 14) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L2 thereto in sequence, stir the reaction at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₇ H ₂₉ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 534.1452; found value: 534.1457.

Elemental analysis: C ₂₇ H ₂₉ FeN ₂ O ₆ : Theoretical value: C, 60.80%; H, 5.48%; N, 5.25%; Found value: C, 60.65%; H, 5.37%; N, 5.17%.

Example 15: The structural formula of bipyridine-bipyridine iron complex (catalyst 15) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L3 thereto in sequence, stir the reaction at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₇ H ₃₃ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 538.1761; found value: 538.1758.

Elemental analysis: C ₂₇ H ₃₃ FeN ₂ O ₆ : Theoretical value: C, 60.34%; H, 6.19%; N, 5.21%; Found value: C, 60.25%; H, 6.34%; N, 5.15%.

Example 16: The structural formula of bipyridine-bipyridine iron complex (catalyst 16) is:

The preparation method is as follows: Under an argon atmosphere, first vacuum bake a 25 mL Schlenk tube three times, then add 20 mL of redistilled cyclohexane, 0.2 mmol Fe(acac) ₃ and 0.2 mmol N,N-bidentate electron-rich compound L4 thereto in sequence, stir and react at room temperature for 1 h, filter, concentrate, and vacuum dry for 12 h to obtain a reddish-brown solid product, i.e., a bipyridine iron complex solution.

Mass spectrum analysis: C ₂₇ H ₃₃ FeN ₂ O _6: [M+H] ⁺ : theoretical value: 538.1761; found value: 538.1759.

Elemental analysis: C ₂₇ H ₃₃ FeN ₂ O ₆ : Theoretical value: C, 60.34%; H, 6.19%; N, 5.21%; Found value: C, 60.25%; H, 6.27%; N, 5.25%.

Example 17: Modified aluminum reagent 1

It is prepared from triisobutylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 6.4 umol of water and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 1.

Example 18: Modified aluminum reagent 2

It is prepared from triisobutylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 12.8 umol of water and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 2.

Example 19: Modified aluminum reagent 3

It is prepared from triisobutylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 25.6 umol of water and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 3.

Example 20: Modified aluminum reagent 4

It is prepared from triisobutylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 0.1 mmol of water and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 4.

Example 21: Modified aluminum reagent 5

It is prepared from trimethylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 6.4 umol of water and 0.1 mmol of trimethylaluminum were mixed to obtain a modified aluminum reagent 5.

Example 22: Modified aluminum reagent 6

It is prepared from triethylaluminum and water. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 6.4 umol of water and 0.1 mmol of triethylaluminum were mixed to obtain a modified aluminum reagent 6.

Example 23: Modified aluminum reagent 7

It is prepared from triisobutylaluminum and cardanol, and the preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first evacuated and baked three times, and 6.4 umol of cardanol and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 7.

Example 24: Modified aluminum reagent 8

It is prepared from triisobutylaluminum and cardanol. The preparation method is as follows: Under an argon atmosphere, a 100 mL Schlenk tube is first vacuum-baked three times, and 12.8 umol of cardanol and 0.1 mmol of triisobutylaluminum are mixed to obtain a modified aluminum reagent 8.

Example 25: Modified aluminum reagent 9

It is prepared from triisobutylaluminum and isooctanoic acid, and the preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 6.4 umol of isooctanoic acid and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 9.

Example 26: Modified aluminum reagent 10

It is prepared from triisobutylaluminum and isooctyl alcohol. The preparation method is as follows:

Under an argon atmosphere, a 100 mL Schlenk tube was first vacuum-baked three times, and 6.4 umol of isooctyl alcohol and 0.1 mmol of triisobutylaluminum were mixed to obtain a modified aluminum reagent 10.

Example 27: Iron-based conjugated diene polymer 1

The preparation method is as follows: under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added to a 100 mL Schlenk tube in sequence, and the mixture is polymerized at 40° C. for 30 min. The reaction is then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant (an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a mass concentration of 1%, the same as in the following examples). After the clear liquid is discarded, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 1.

Example 28: Iron-based conjugated diene polymer 2

The preparation method is as follows: in an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added to a 100 mL Schlenk tube in sequence, and polymerized at 50° C. for 30 min, and then the reaction is terminated with a mixed solution of 10 mL methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant, and after the clear liquid is poured off, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 2. The hydrogen spectrum, carbon spectrum, GPC test, and gel test of the obtained iron-based conjugated diene polymer 2 are shown in Figures 1-4.

GPC test results are shown in Table 1-3:

Table 1 Molecular weight information

Table 2 Peak information table

Table 3 Peak tracking information table

Example 29: Iron-based conjugated diene polymer 3

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 60° C. for 30 min. The reaction is then terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After the clear liquid is discarded, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 3.

Example 30: Iron-based conjugated diene polymer 4

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 70 ° C for 30 min. The reaction is then terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After the clear liquid is discarded, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 4.

Example 31: Iron-based conjugated diene polymer 5

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 90 ° C for 30 min. The reaction is then terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After the clear liquid is discarded, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 5.

Example 32: Iron-based conjugated diene polymer 6

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), THF (50 ppm), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 60 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 6.

Example 33: Iron-based conjugated diene polymer 7

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), THF (200 ppm), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 60 ° C for 30 min. The reaction is then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 7.

Example 34: Iron-based conjugated diene polymer 8

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (37.5 mL), isoprene (7.5 mL, 75.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 250 mL Schlenk tube, and the polymerization is carried out at 40 ° C for 30 min. Then, the reaction is terminated with 15 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.5 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 8.

Example 35: Iron-based conjugated diene polymer 9

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (37.5 mL), isoprene (7.5 mL, 75.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 250 mL Schlenk tube, and the mixture is polymerized at 50 ° C for 30 min. The reaction is then terminated with 15 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.5 mL of an antioxidant. After discarding the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 9.

Example 36: Iron-based conjugated diene polymer 10

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 2 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 50 °C for 10 min. The reaction is then terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 10.

Example 37: Iron-based conjugated diene polymer 11

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 3 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 11.

Example 38: Iron-based conjugated diene polymer 12

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 4 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 10 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 12.

Example 39: Iron-based conjugated diene polymer 13

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 5 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 13.

Example 40: Iron-based conjugated diene polymer 14

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 6 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 14.

Example 41: Iron-based conjugated diene polymer 15

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 7 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 15.

Example 42: Iron-based conjugated diene polymer 16

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 8 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 16.

Example 43: Iron-based conjugated diene polymer 17

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 9 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the mixture is polymerized at 50 °C for 30 min. The reaction is then terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 17.

Example 44: Iron-based conjugated diene polymer 18

The preparation method is as follows: Under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 10 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) are added in sequence to a 100 mL Schlenk tube, and the polymerization is carried out at 50 ° C for 30 min. Then, the reaction is terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After pouring off the clear liquid, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 18.

Example 45: Iron-based conjugated diene polymer 19

The preparation method is as follows: under an argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 1 (1.0 ml, 10 μmol) are added to a 100 mL Schlenk tube in sequence, and the mixture is polymerized at 50° C. for 30 min, and then the reaction is terminated with a mixed solution of 10 mL of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After the clear liquid is discarded, the polymer is washed three times with ethanol to obtain an iron-based conjugated diene polymer 19. The DSC graph of the obtained iron-based conjugated diene polymer 19 is shown in FIG5 .

Example 46: Iron-based conjugated diene polymer 20

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), catalyst 1 (1.0 ml, 10 μmol), THF (50 ppm) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 20.

Example 47: Iron-based conjugated diene polymer 21

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 3 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 21.

Example 48: Iron-based conjugated diene polymer 22

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 4 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 22.

Example 49: Iron-based conjugated diene polymer 23

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 5 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 23.

Example 50: Iron-based conjugated diene polymer 24

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 6 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 24.

Example 51: Iron-based conjugated diene polymer 25

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 7 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 25.

Example 52: Iron-based conjugated diene polymer 26

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 8 (1.0 ml, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 50 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 26.

Example 53: Iron-based conjugated diene polymer 27

Under an argon atmosphere, anhydrous cyclohexane (35 mL), butadiene (3.5 mL, 40.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), and catalyst 2 (1.0 ml, 10 μmol) were added to a 100 mL Schlenk tube in sequence, and polymerized at 50° C. for 30 min. The reaction was then terminated with 14 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.4 mL of an antioxidant. After the clear liquid was discarded, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 27. The DSC graph of the obtained iron-based conjugated diene polymer 27 is shown in FIG6 .

Example 54: Iron-based conjugated diene polymer 28

Under an argon atmosphere, anhydrous cyclohexane (35 mL), butadiene (1.75 mL, 20.0 mmol) and isoprene (2.0 mL, 20.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), catalyst 2 (1.0 ml, 10 μmol) were added to a 250 mL Schlenk tube in sequence, and polymerized at 50° C. for 30 min, and then the reaction was terminated with 14 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.4 mL of an antioxidant. After the clear liquid was poured off, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 28. The DSC graph of the obtained iron-based conjugated diene polymer 28 is shown in FIG7 .

Example 55: Iron-based conjugated diene polymer 29

Under argon atmosphere, anhydrous cyclohexane (35 mL), butadiene (0.875 mL, 10.0 mmol) and isoprene (3.0 mL, 30.0 mmol), modified aluminum reagent 1 (0.4 mmol, 40 eq.), catalyst 2 (1.0 ml, 10 μmol) were added in sequence to a 250 mL Schlenk tube, and the mixture was polymerized at 50 °C for 30 min. The reaction was then terminated with 14 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.4 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 29.

Example 56: Iron-based conjugated diene polymer 30

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 0°C for 10 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 30.

Example 57: Iron-based conjugated diene polymer 31

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 10°C for 10 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 31.

Example 58: Iron-based conjugated diene polymer 32

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 30 ° C for 10 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 32.

Example 59: Iron-based conjugated diene polymer 33

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40°C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 33.

Example 60: Iron-based conjugated diene polymer 34

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 50°C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 34.

Example 61: Iron-based conjugated diene polymer 35

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5 mL, 50.0 mmol), modified aluminum reagent 1 (0.1 mmol, 20 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 35.

Example 62: Iron-based conjugated diene polymer 36

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5 mL, 50.0 mmol), modified aluminum reagent 1 (0.3 mmol, 60 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 36.

Example 63: Iron-based conjugated diene polymer 37

Under argon atmosphere, anhydrous cyclohexane (37.5 mL), isoprene (7.5 mL, 75.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 15 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.5 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 37.

Example 64: Iron-based conjugated diene polymer 38

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 2 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 38.

Example 65: Iron-based conjugated diene polymer 39

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 3 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 39.

Example 66: Iron-based conjugated diene polymer 40

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 4 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 40.

Example 67: Iron-based conjugated diene polymer 41

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 5 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 41.

Example 68: Iron-based conjugated diene polymer 42

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), modified aluminum reagent 6 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40°C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 42.

Example 69: Iron-based conjugated diene polymer 43

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 7 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 43.

Example 70: Iron-based conjugated diene polymer 44

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 8 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 44.

Example 71: Iron-based conjugated diene polymer 45

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 9 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 45.

Example 72: Iron-based conjugated diene polymer 46

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 10 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 46.

Example 73: Iron-based conjugated diene polymer 47

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 9 (4.1 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 47.

Example 74: Iron-based conjugated diene polymer 48

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 10 (4.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 48.

Example 75: Iron-based conjugated diene polymer 49

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 11 (4.4 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 49.

Example 76: Iron-based conjugated diene polymer 50

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 12 (4.4 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and the polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 50.

Example 77: Iron-based conjugated diene polymer 51

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 13 (5.1 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 51.

Example 78: Iron-based conjugated diene polymer 52

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 15 (5.4 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 52.

Example 79: Iron-based conjugated diene polymer 53

Under argon atmosphere, anhydrous cyclohexane (25 mL), isoprene (5.00 mL, 50.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 16 (5.4 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 °C for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 53.

Example 80: Iron-based conjugated diene polymer 54

Under argon atmosphere, anhydrous cyclohexane (35 mL), butadiene (3.5 mL, 40.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), and catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 100 mL Schlenk tube, and polymerization was carried out at 40 ° C for 30 min. The reaction was then terminated with 14 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.4 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 54.

Example 81: Iron-based conjugated diene polymer 55

Under argon atmosphere, anhydrous cyclohexane (35 mL), butadiene (1.75 mL, 20.0 mmol) and isoprene (2.0 mL, 20.0 mmol), modified aluminum reagent 1 (0.2 mmol, 40 eq.), catalyst 14 (5.3 mg, 10 μmol) were added in sequence to a 250 mL Schlenk tube, and the mixture was polymerized at 40 °C for 30 min. The reaction was then terminated with 14 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1.4 mL of an antioxidant. After discarding the clear liquid, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 55.

Comparative Example 1 (vs. Example 46): Iron-based conjugated diene polymer 56

Under argon atmosphere, to a 100 mL Schlenk tube were added anhydrous cyclohexane (25 mL), isoprene (5.0 mL, 50.0 mmol), [Ph ₃ C] ⁺ [B(C ₆ F ₅ ) ₄ ] ^- (9.2 mg, 10 μmol), Al ⁱ Bu ₃ (0.4 mmol, 40 eq.), catalyst 1 (1.0 ml, 10 μmol), and THF (50 ppm) in sequence, and the polymerization was carried out at 50° C. for 30 min. The reaction was then terminated with 10 mL of a mixed solution of methanol and hydrochloric acid (MeOH/HCl volume ratio = 50/1) and 1 mL of an antioxidant. After discarding the supernatant, the polymer was washed three times with ethanol to obtain an iron-based conjugated diene polymer 56.

The physical parameters of the iron-based conjugated diene polymers obtained in the above Examples 27-81 and Comparative Example 1 are shown in Table 4.

Table 4

Comparative analysis

In order to better prove that the bipyridine iron complex/modified aluminum catalyst system designed by the present invention is different from the existing conjugated diene catalyst system, it has good polar functional group tolerance, and the introduction of part of THF in the system does not affect the reaction yield. Therefore, the modified aluminum system (Example 46) and the existing conjugated diene three-component system (Comparative Example 1) are compared in the same THF concentration solvent, and it can be found that the reaction yield of the modified aluminum system of the present invention is not affected, and complete conversion can be achieved, showing good polar functional group tolerance, and the yield is also significantly better than the yield of the existing conjugated diene three-component system.

Performance Testing

The catalysts in Examples 1, 2, 13, and 14 were used as representatives to conduct a comparative experiment on solubility with two ferric chloride catalysts. The test method for solubility comparison was as follows: 10 mg of 5 different catalysts were respectively dissolved in 3 mL of n-hexane solvent. The two ferrous chloride catalysts had very poor solubility, and most of the solids remained in the bottle. The bipyridyl iron complex solutions in the present invention were all transparent and uniform solutions, which could ensure that the reaction was carried out in a homogeneous polymerization system, which was conducive to the participation of the catalyst in the reaction for catalytic polymerization, thereby obtaining a higher reaction yield and showing a higher activity.

Claims (13)

1. The preparation method of the iron conjugated diene polymer is characterized by comprising the following steps:

adding a bipyridine iron complex, a modified aluminum catalytic system, conjugated diene monomer and a solvent into a reactor under the argon atmosphere to form a reaction system, stirring at 0-90 ℃ for polymerization for 10-30 min, adding a quenching agent and an anti-aging agent after the reaction is finished, washing and drying to obtain an iron conjugated diene polymer;

wherein the molar ratio of the conjugated diene monomer to the iron element in the bipyridine iron complex is (1000-20000) 1; the molar ratio of the aluminum element in the modified aluminum to the iron element in the bipyridyl iron complex is (10-100) 1; the conjugated diene compound is at least one of isoprene and butadiene, and the solvent is a nonpolar solvent or a polar/nonpolar mixed solvent, wherein the nonpolar solvent is at least one of cyclohexane, n-hexane, n-heptane, petroleum ether, benzene, toluene and xylene, and the polar solvent is at least one of tetrahydrofuran, acetone, acetonitrile, pyridine and chlorobenzene;

In the method, the bipyridyl iron complex is prepared by the following steps:

adding an equimolar amount of an N, N-bidentate electron-rich compound and an organic iron compound into an anhydrous reaction solvent in an argon atmosphere, and stirring and reacting for 1-36 hours at 0-60 ℃ to obtain a bipyridine iron complex;

the obtained bipyridine iron complex has the following structural general formula:

；

the modified aluminum is prepared by the following steps:

adding a modifier into an organic aluminum compound in an argon atmosphere, and stirring and reacting for 1 min-1 h at the temperature of-10-30 ℃ to obtain the modified aluminum compound, wherein the molar ratio of the organic aluminum compound to the modifier is 1: (0.01-2);

the organic aluminum compound is selected from at least one of trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, triisopropylaluminum, diethylaluminum chloride, diisobutylaluminum chloride, dimethylaluminum chloride, diethylaluminum hydride, diisobutylaluminum hydride and dimethylaluminum hydride;

the modifier is at least one selected from water, cardanol, phenol, cresol, naphthol, nitrophenol, 2, 6-di-tert-butyl-p-cresol, 2, 6-di-tert-butylphenol, p-tert-butyl catechol, methanol, ethanol, propanol, n-octanol, isooctanol, n-hexanol, tert-butanol, triphenylmethanol, benzyl alcohol, formic acid, acetic acid, isooctanoic acid, benzoic acid, stearic acid, naphthenic acid and neodecanoic acid.

2. The preparation method according to claim 1, wherein the proportion of 3,4- (1, 2-) structure is 60% -80%, the proportion of 1,4 structure is 20% -40%, the gel content is < 1%, the glass transition temperature is-80 ℃ -10 ℃, the number average molecular weight is 10 ten thousand-80 ten thousand, and the molecular weight distribution is 1.0-5.0.

3. The method of claim 1, wherein the N, N-bidentate electron-rich compound is selected from one of the following structures:

、、、。

4. the production method according to claim 1, wherein the organic iron compound Fe (X) n is at least one selected from the group consisting of iron acetylacetonate, iron naphthenate, iron isooctanoate, iron neodecanoate, iron acetylacetonate, iron acetate, iron caproate, iron stearate, and iron caprylate.

5. The method according to claim 1, wherein the anhydrous reaction solvent is at least one selected from the group consisting of aliphatic saturated hydrocarbons, aromatic hydrocarbons, aryl halides and cycloalkanes.

6. The method according to claim 5, wherein the anhydrous reaction solvent is at least one selected from cyclohexane, n-hexane, ethanol, methylene chloride, dichloropropane, toluene and chlorobenzene.

7. The preparation method according to claim 1, wherein in the preparation of the bipyridyl iron complex, the reaction temperature is 20-40 ℃ and the reaction time is 1-12 h.

8. The method according to claim 1, wherein when the conjugated diene compound is a mixture of isoprene and butadiene, the ratio of isoprene is 1% to 99%.

9. The method according to claim 1, wherein the concentration of the polar solvent in the polar/nonpolar mixed solvent is 0 ppm to 400 ppm.

10. The process according to claim 1, wherein the volume ratio of conjugated diene monomer to solvent is 1: (1-20).

11. The process according to claim 1, wherein in the preparation of the iron-based conjugated diene polymer, the reaction temperature is 40 to 70 ℃ and the reaction time is 30 minutes.

12. The method of claim 1, wherein the quenching agent is a mixed solution of concentrated hydrochloric acid and methanol, wherein the volume ratio of methanol to concentrated hydrochloric acid is 50:1, a step of; the volume ratio of the quenching agent to the solvent is 1:2.5.

13. the method according to claim 1, wherein the volume ratio of the anti-aging agent to the solvent is 1:25, and the anti-aging agent is an ethanol solution of 2, 6-di-tert-butyl-4-methylphenol with a mass concentration of 1%.