Process for the preparation of polyconjugated dienes, products and uses
By using an iron-based cycloboroxane catalytic system, employing N,N-bident iron carboxylate catalysts and cycloboroxane compounds, the problems of high cost and low yield of iron-based catalysts have been solved, achieving efficient and low-cost conjugated diene polymerization, which is suitable for industrial applications.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2023-02-24
- Publication Date
- 2026-06-09
AI Technical Summary
In existing iron-based conjugated diene catalytic systems, it is difficult to balance high activity and low cost. Boron co-catalysts are expensive, which limits their industrial application, and the reaction yield is low.
An iron-based cycloboroxane catalytic system was adopted, using N,N-bident iron carboxylate catalyst, alkyl aluminum and cycloboroxane compounds to adjust the Lewis acidity of the metal center, stabilize the active center, reduce costs and improve reaction yield.
This study enabled the application of inexpensive cycloboroxane compounds in the polymerization of conjugated dienes, improving reaction yield, enhancing flowability, and avoiding problems such as sticking to the reactor, making them suitable for industrial applications.
Smart Images
Figure CN118546280B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of conjugated diene catalytic polymerization technology, specifically to methods, products, and applications for preparing polyconjugated dienes. Background Technology
[0002] Iron is the most abundant transition metal in the Earth's crust. Due to its economic and environmental friendliness, it has received increasing attention in the field of catalysis. In the field of conjugated diene polymerization, a variety of highly active and selective iron-based catalysts with ammonia and phosphorus compounds as ligands or catalyst components have been developed. Based on the catalyst composition, conjugated diene polymers such as butadiene, isoprene, and 1,3-pentadiene with different microstructures and regularity can be prepared.
[0003] Currently, iron catalysts used in the catalysis of conjugated dienes have been developed to pyridineimine iron complexes. Combined with alkylaluminum and boron co-catalysts, these can effectively form homogeneous catalytic systems, achieving high molecular weight (2.0 × 10⁻⁶) isomers in the polymerization of isoprene. 5 Polymers with g / mol g / mol g / mol g / mol g / mol g / mol (PDI = 1.4-3.3 g / mol ... + [B(CF5)4] - Boron co-catalysts are very expensive, and if they are not used, the yield of the polymerization reaction will drop sharply to about 40% due to the weak Lewis acidity of the iron metal center and the lack of a co-catalyst to improve the stability of the metal center. Therefore, finding a cheap alternative to boron co-catalysts is of great industrial significance. Summary of the Invention
[0004] The purpose of this invention is to overcome the technical problem of balancing high activity and low cost in existing iron-based polyconjugated diene catalytic systems, and to provide a method, product, and application for preparing polyconjugated dienes. This invention utilizes an iron-based cycloboroxane catalytic system to prepare polyconjugated dienes, thereby reducing costs while increasing reaction yield.
[0005] To achieve the above objectives, a first aspect of the present invention provides a method for preparing polyconjugated dienes, the method comprising: polymerizing a conjugated diene in the presence of an iron-based cycloboroxane catalytic system to obtain a polyconjugated diene; wherein the iron-based cycloboroxane catalytic system comprises an N,N-bidentate iron carboxylate catalyst, an alkyl aluminum, and a cycloboroxane compound.
[0006] A second aspect of the present invention provides a polyconjugated diene prepared by the aforementioned method, wherein the polyconjugated diene has a number-average molecular weight of 25,000-2,000,000 g / mol and a molecular weight distribution of 1.5-5.5; wherein the polyconjugated diene has a molar content of 60-80% for the 3,4-structure and a molar content of 20-40% for the 1,4-structure.
[0007] A third aspect of the present invention provides the application of the aforementioned polyconjugated diene in the preparation of automobile tires.
[0008] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:
[0009] 1) This invention applies inexpensive cycloboroxane compounds to the polymerization of conjugated dienes. The electron-donating cycloboroxane compounds are used as the third component in the catalytic system. When they coordinate with metals, they can adjust the Lewis acidity of the metal center and maintain the stability of the metal center, thereby achieving stable and efficient polymerization of conjugated dienes and reducing the cost of the catalytic system used for the catalytic polymerization of conjugated dienes.
[0010] 2) This invention is the first to introduce cycloboroxane compounds into an iron-based catalytic system and use them for the catalytic polymerization of conjugated dienes. Compared with other known catalytic systems, the introduction of cycloboroxane compounds greatly improves the fluidity of the reaction system, and the product after quenching has low viscosity, effectively avoiding problems often encountered in other catalytic systems such as sticking to the reactor and difficulty in feeding. It is very suitable for factory equipment such as reactors and tubular reactors, and has high potential for industrial application. Attached Figure Description
[0011] Figure 1 The polyisoprene obtained in Example 1 of this invention 1 H NMR spectrum;
[0012] Figure 2 The GPC spectrum of polyisoprene obtained in Example 1 of this invention is shown.
[0013] Figure 3 The image shows the DSC spectrum of polyisoprene obtained in Example 1 of this invention. Detailed Implementation
[0014] The endpoints and any values of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of the various ranges, the endpoint values of the various ranges and individual point values, and individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.
[0015] The first aspect of the present invention provides a method for preparing polyconjugated dienes, the method comprising: polymerizing a conjugated diene in the presence of an iron-based cycloboroxane catalytic system to obtain a polyconjugated diene; wherein the iron-based cycloboroxane catalytic system comprises an N,N-bident iron carboxylate catalyst, alkyl aluminum, and cycloboroxane compounds.
[0016] This invention applies inexpensive cycloboroxane compounds to the polymerization of conjugated dienes. Cycloboroxane compounds have a special cyclic electron-rich structure, which promotes the formation of active centers in the polymerization reaction and stabilizes the active centers by interacting with positively charged N,N-bident ferric carboxylate metal active centers.
[0017] This invention uses electron-donating cycloboroxane compounds as the third component in the catalytic system. When these compounds coordinate with metals, they can adjust the Lewis acidity of the metal center and maintain its stability, thereby achieving stable and efficient conjugated diene polymerization and reducing the cost of the catalytic system used for conjugated diene polymerization. This provides a possible solution to the problem of high catalytic system costs.
[0018] In some embodiments of the present invention, the N,N-bident ferric carboxylate catalyst is selected from one or more compounds having the following structural formulas:
[0019]
[0020]
[0021] Among them, EHA is Naph for
[0022] In the above structural formulas, the dashed lines represent coordinate bonds and the solid lines represent ionic bonds in the bonds connecting to Fe atoms. Fe in bonds I, II, III, and IV has a +3 valence, while Fe in bonds V, VI, VII, and VIII has a +2 valence. In the structures shown by EHA and Naph, the wavy lines indicate the positions where Fe atoms are connected.
[0023] In some embodiments of the present invention, the general structural formula of the cycloboroxane compound is: Wherein, R is a substituted or unsubstituted C2-C10 alkyl or a substituted or unsubstituted C6-C10 aryl.
[0024] In this invention, the substituted or unsubstituted C2-C10 alkyl groups can be substituted or unsubstituted straight-chain or branched alkyl groups, including but not limited to: methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, hexyl, etc.; the substituted or unsubstituted C6-C10 aryl groups include but not limited to: phenyl, fluorophenyl, bromophenyl, tolyl, ethylphenyl, etc.
[0025] In some embodiments of the present invention, the cycloboroxane compound is selected from one or more compounds having the following structural formulas:
[0026]
[0027] In some embodiments of the present invention, the alkylaluminum is selected from one or more of trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, triisobutylaluminum, and triisopropylaluminum.
[0028] Extensive research has revealed that excessively high dosages of cycloboroxane compounds result in high costs, while excessively low dosages lead to low reactivity. Therefore, the dosage of cycloboroxane compounds needs to be determined based on a comprehensive consideration of both reactivity and cost.
[0029] In some embodiments of the present invention, the molar ratio of boron in the cycloboroxane compound to iron in the N,N-bidentate iron carboxylate catalyst is (0.1-20):1, for example, 0.1:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, and any value within any range of two such values, preferably (0.1-10):1.
[0030] In some embodiments of the present invention, the molar ratio of aluminum in the alkylaluminum to iron in the N,N-bidentate iron carboxylate catalyst is (1-100):1, for example, 1:1, 5:1, 10:1, 20:1, 30:1, 40:1, 45:1, 50:1, 60:1, 65:1, 70:1, 80:1, 90:1, 100:1, and any value within the range of any two values, preferably 40-60:1.
[0031] In some embodiments of the present invention, the molar ratio of the conjugated diene to the iron element in the N,N-bident carboxylic acid iron catalyst is (5000-50000):1, for example, 5000:1, 8000:1, 10000:1, 12000:1, 15000:1, 18000:1, 20000:1, 25000:1, 30000:1, 35000:1, 40000:1, 45000:1, 50000:1, and any value within the range of any two values, preferably 10000-30000:1.
[0032] In some embodiments of the present invention, the conjugated diene is one or more of isoprene, butadiene, β-farnesene, and myrcene.
[0033] In some embodiments of the present invention, the method specifically includes the following steps:
[0034] Under anhydrous and oxygen-free conditions, conjugated dienes are polymerized in a solvent in the presence of an N,N-bidentate iron carboxylate catalyst, alkyl aluminum, and cycloboronic alkane compounds to obtain polyconjugated dienes.
[0035] In some embodiments of the present invention, the temperature of the polymerization reaction is 0-100°C, preferably 30-60°C; and the time is 10-120 min, preferably 30-120 min.
[0036] In some embodiments of the present invention, the polymerization reaction is carried out under stirring conditions, wherein the stirring speed is 100-1000 rpm, preferably 200-800 rpm, and more preferably 650 rpm.
[0037] In some embodiments of the present invention, the volume ratio of the conjugated diene to the solvent is 1:(1-20), for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, and any value within the range of any two values, preferably 1:(5-15), more preferably 1:10.
[0038] In some embodiments of the present invention, the solvent is a non-polar solvent; preferably, the non-polar solvent is one or more of cyclohexane, n-hexane, petroleum ether, toluene, and xylene.
[0039] In some embodiments of the present invention, the method further includes: after the polymerization reaction is completed, adding a quencher and an anti-aging agent.
[0040] In some embodiments of the present invention, the volume ratio of the quenching agent to the solvent is 1:(10-100), for example 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, and any value within the range of any two values, preferably 1:(30-60), more preferably 1:50.
[0041] In some embodiments of the present invention, the volume ratio of the anti-aging agent to the solvent is 1:(10-100), for example, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:85, 1:90, 1:95, 1:100, and any value within the range of any two values, preferably 1:(10-50), more preferably 1:25.
[0042] In some embodiments of the present invention, the quenching agent is a mixed solution of concentrated hydrochloric acid and methanol; preferably, the volume ratio of methanol to concentrated hydrochloric acid is 1-200:1, more preferably 1-100:1, and even more preferably 50:1.
[0043] In some embodiments of the present invention, the anti-aging agent is an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a mass concentration of 1-10%, preferably a 1-5% ethanol solution of 2,6-di-tert-butyl-4-methylphenol, and more preferably a 1% ethanol solution of 2,6-di-tert-butyl-4-methylphenol.
[0044] This invention is the first to introduce cycloboroxane compounds into an iron-based catalytic system and use them for the catalytic polymerization of conjugated dienes. Compared with other known catalytic systems, the introduction of cycloboroxane compounds greatly improves the fluidity of the reaction system, and the quenched product has low viscosity, effectively avoiding problems often encountered in other catalytic systems such as sticking to the reactor and difficulty in feeding. It is very suitable for industrial equipment such as reactors and tubular reactors, and has high potential for industrial application.
[0045] In this invention, a catalytic system composed of 1 equivalent or even 0.1 equivalent of cycloboroxane compounds can achieve a yield of >99% for polyconjugated dienes.
[0046] A second aspect of the present invention provides a polyconjugated diene prepared by the aforementioned method, wherein the polyconjugated diene has a number-average molecular weight of 2.5-2,000,000 g / mol and a molecular weight distribution of 1.5-5.5; wherein the polyconjugated diene has a molar content of 60-80% for the 3,4-structure and a molar content of 20-40% for the 1,4-structure.
[0047] A third aspect of the present invention provides the application of the aforementioned polyconjugated diene in the preparation of automobile tires.
[0048] The automobile tires prepared using the polyconjugated diene of this invention have the characteristics of high wet skid resistance and low rolling resistance.
[0049] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.
[0050] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.
[0051] In the following embodiments:
[0052] The preparation method of N,N-bident iron carboxylate catalyst includes the following steps:
[0053] Under an argon atmosphere, equimolar amounts of N,N-bident electron-rich compounds, ferric isooctanoate, and ferric naphthenate compounds were added to an anhydrous reaction solvent, and the mixture was stirred at 0-60°C for 1-36 h to obtain N,N-bident ferric carboxylate catalysts. Specific preparation methods for N,N-bident ferric carboxylate catalysts I-VIII can be found in patent CN114249849A.
[0054] Example 1
[0055] A method for efficiently preparing polyisoprene using an iron-based cycloboroxane catalytic system includes the following steps:
[0056] Under an argon atmosphere, anhydrous cyclohexane (100 mL), isoprene (6.8 g, 100 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added, and the reaction was terminated with 1 mL of a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol, and the resulting polymer was dried under vacuum to constant weight to obtain polyisoprene elastomer.
[0057] Test results: Yield of polyisoprene elastomer: 99%, number average molecular weight (M n ): 7.0×10 5 g / mol, molecular weight distribution (PDI): 2.4; molar content of different structures in the elastomer: 1,4-structure accounts for 37%, 3,4-structure accounts for 63%, glass transition temperature is -1.0℃.
[0058] 1 H NMR spectrum: Characterized by Bruker 400M nuclear magnetic resonance spectrometer.
[0059] GPC chromatogram: The polymer was dissolved in tetrahydrofuran at a concentration of 5 mg / mL, and polystyrene was used as a standard. The chromatogram was then obtained by gel permeation chromatography.
[0060] DSC spectrum: The program was set to an initial temperature of -100℃, an ending temperature of 120℃, and a heating rate of 10K / min. The spectrum was obtained using conventional detection methods.
[0061] The polyisoprene elastomer obtained in this embodiment 1 The H NMR spectrum, GPC spectrum, and DSC spectrum are shown below. Figure 1-3 As shown; among them, by Figure 1As can be seen, by integrating the proportions of characteristic hydrogens represented by the 3,4 structure and the 1,2 structure, the polymer's 3,4 structure and 1,2 structure account for 63% and 37%, respectively. Figure 2 It can be seen that the number-average molecular weight (M) of polyisoprene is... n ) is 7.0×10 5 g / mol. From Figure 3 As can be seen, the midpoint indicates that the glass transition temperature of polyisoprene is -1.0℃.
[0062] Example 2
[0063] Polyisoprene was prepared according to the method of Example 1, except that the amount of cycloboroxane compound A was (15.5 mg, 50 μmol), and the other steps and parameters were the same as in Example 1.
[0064] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 5.3×10 5 g / mol, molecular weight distribution (PDI): 2.4; molar content of different structures in the elastomer: 1,4-structure accounts for 40%, 3,4-structure accounts for 60%, glass transition temperature is -0.2℃.
[0065] Example 3
[0066] Polyisoprene was prepared according to the method of Example 1, except that the reaction temperature was 50°C, and the other steps and parameters were the same as in Example 1.
[0067] Test results: Yield of polyisoprene elastomer: 96%, number average molecular weight (M n ): 6.2×10 5 g / mol, molecular weight distribution (PDI): 2.3; molar content of different structures in the elastomer: 1,4-structure accounts for 44%, 3,4-structure accounts for 66%, glass transition temperature is -2.7℃.
[0068] Example 3
[0069] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound B in an amount of 3.7 mg (10 μmol), and 50 mL of anhydrous cyclohexane was used. Other steps and parameters were the same as in Example 1.
[0070] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 7.0×10 5g / mol, molecular weight distribution (PDI): 2.5; molar content of different structures in the elastomer: 1,4-structure accounts for 32%, 3,4-structure accounts for 68%, glass transition temperature is 3.6℃.
[0071] Example 4
[0072] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound B in an amount of 7.4 mg (20 μmol), and 50 mL of anhydrous cyclohexane was used. Other steps and parameters were the same as in Example 1.
[0073] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 6.1×10 5 g / mol, molecular weight distribution (PDI): 2.4; molar content of different structures in the elastomer: 1,4-structure accounts for 35%, 3,4-structure accounts for 65%, glass transition temperature is -3.5℃.
[0074] Example 5
[0075] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound C in an amount of (4.3 mg, 10 μmol), and the other steps and parameters were the same as in Example 1.
[0076] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 5.0×10 5 g / mol, molecular weight distribution (PDI): 2.7; molar content of different structures in the elastomer: 1,4-structure accounts for 25%, 3,4-structure accounts for 75%, glass transition temperature is -4.4℃.
[0077] Example 6
[0078] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound C in an amount of (8.6 mg, 20 μmol), and the other steps and parameters were the same as in Example 1.
[0079] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 4.5×10 5 g / mol, molecular weight distribution (PDI): 2.1; molar content of different structures in the elastomer: 1,4-structure accounts for 22%, 3,4-structure accounts for 78%, glass transition temperature is -0.5℃.
[0080] Example 7
[0081] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound D in an amount of (4.9 mg, 10 μmol), and the other steps and parameters were the same as in Example 1.
[0082] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 8.0×10 5 g / mol, molecular weight distribution (PDI): 2.3; molar content of different structures in the elastomer: 1,4-structure accounts for 37%, 3,4-structure accounts for 63%, glass transition temperature is 4.5℃.
[0083] Example 8
[0084] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound D in an amount of (24.5 mg, 50 μmol), and the other steps and parameters were the same as in Example 1.
[0085] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 6.9×10 5 g / mol, molecular weight distribution (PDI): 2.8; molar content of different structures in the elastomer: 1,4-structure accounts for 36%, 3,4-structure accounts for 64%, glass transition temperature is 4.1℃.
[0086] Example 9
[0087] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound E in an amount of (1.26 mg, 10 μmol), and the other steps and parameters were the same as in Example 1.
[0088] Test results: Yield of polyisoprene elastomer: 92%, number average molecular weight (M n ): 5.2×10 5 g / mol, molecular weight distribution (PDI): 2.5; molar content of different structures in the elastomer: 1,4-structure accounts for 33%, 3,4-structure accounts for 67%, glass transition temperature is 2.7℃.
[0089] Example 10
[0090] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was replaced with cycloboroxane compound F in an amount of (1.68 mg, 10 μmol), and the other steps and parameters were the same as in Example 1.
[0091] Test results: Yield of polyisoprene elastomer: 95%, number average molecular weight (M n ): 7.1×10 5 g / mol, molecular weight distribution (PDI): 2.3; molar content of different structures in the elastomer: 1,4-structure accounts for 35%, 3,4-structure accounts for 66%, glass transition temperature is 1.9℃.
[0092] Example 11
[0093] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst II, and the amount was (6.4 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0094] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 5.7×10 5 g / mol, molecular weight distribution (PDI): 2.2; molar content of different structures in the elastomer: 1,4-structure accounts for 25%, 3,4-structure accounts for 75%, glass transition temperature is -7.8℃.
[0095] Example 12
[0096] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst III, and the amount was (6.7 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0097] Test results: Yield of polyisoprene elastomer: 90%, number average molecular weight (M n ): 5.1×10 5 g / mol, molecular weight distribution (PDI): 3.4; molar content of different structures in the elastomer: 1,4-structure accounts for 29%, 3,4-structure accounts for 71%, glass transition temperature is -1.7℃.
[0098] Example 13
[0099] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst IV, and the amount was (6.7 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0100] Test results: Yield of polyisoprene elastomer: 92%, number average molecular weight (M n ): 4.5×10 5g / mol, molecular weight distribution (PDI): 2.9; molar content of different structures in the elastomer: 1,4-structure accounts for 22%, 3,4-structure accounts for 78%, glass transition temperature is 1.7℃.
[0101] Example 14
[0102] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst V, and the amount was (5.6 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0103] Test results: Yield of polyisoprene elastomer: 96%, number average molecular weight (M n ): 3.5×10 5 g / mol, molecular weight distribution (PDI): 5.0; molar content of different structures in the elastomer: 1,4-structure accounts for 37%, 3,4-structure accounts for 63%, glass transition temperature is 7.6℃.
[0104] Example 15
[0105] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst VI, and the amount was (5.8 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0106] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 3.6×10 5 g / mol, molecular weight distribution (PDI): 3.0; molar content of different structures in the elastomer: 1,4-structure accounts for 34%, 3,4-structure accounts for 66%, glass transition temperature is 5.5℃.
[0107] Example 16
[0108] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst VII, and the amount was (5.9 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0109] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 5.3×10 5 g / mol, molecular weight distribution (PDI): 2.5; molar content of different structures in the elastomer: 1,4-structure accounts for 33%, 3,4-structure accounts for 67%, glass transition temperature is 3.2℃.
[0110] Example 17
[0111] Polyisoprene was prepared according to the method of Example 1, except that N,N-bidentent iron carboxylate catalyst I was replaced with N,N-bidentent iron carboxylate catalyst VIII, and the amount was (5.9 mg, 10 μmol). Other steps and parameters were the same as in Example 1.
[0112] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 6.1×10 5 g / mol, molecular weight distribution (PDI): 2.3; molar content of different structures in the elastomer: 1,4-structure accounts for 32%, 3,4-structure accounts for 68%, glass transition temperature is 9.8℃.
[0113] Example 18
[0114] Polyisoprene was prepared according to the method of Example 1, except that the amount of cycloboroxane compound A was (0.3 mg, 1 μmol), and the other steps and parameters were the same as in Example 1.
[0115] Test results: Yield of polyisoprene elastomer: >99%, number average molecular weight (M n ): 6.5×10 5 g / mol, molecular weight distribution (PDI): 2.5; molar content of different structures in the elastomer: 1,4-structure accounts for 34%, 3,4-structure accounts for 66%, glass transition temperature is 7.4℃.
[0116] Example 19
[0117] Polyisoprene was prepared according to the method of Example 1, except that the amount of cycloboroxane compound A was (62 mg, 200 μmol), and the other steps and parameters were the same as in Example 1.
[0118] Test results: Yield of polyisoprene elastomer: 98%, number average molecular weight (M n ): 5.9×10 5 g / mol, molecular weight distribution (PDI): 2.2; molar content of different structures in the elastomer: 1,4-structure accounts for 33%, 3,4-structure accounts for 67%, glass transition temperature is 4.9℃.
[0119] Example 20
[0120] Polyisoprene was prepared according to the method of Example 1, except that the amount of cycloboroxane compound A was (0.09 mg, 0.3 μmol), and the other steps and parameters were the same as in Example 1.
[0121] Test results: No polymer was generated.
[0122] Example 21
[0123] Polyisoprene was prepared according to the method of Example 1, except that the amount of cycloboroxane compound A was (77.5 mg, 250 μmol), and the other steps and parameters were the same as in Example 1.
[0124] Test results: Yield of polyisoprene elastomer: 92%, number average molecular weight (M n ): 8.1×10 5 g / mol, molecular weight distribution (PDI): 2.3; molar content of different structures in the elastomer: 1,4-structure accounts for 31%, 3,4-structure accounts for 69%, glass transition temperature is 1.3℃.
[0125] Example 22
[0126] A method for efficiently preparing polybutadiene using an iron-based cycloborone catalytic system includes the following steps:
[0127] Under an argon atmosphere, anhydrous cyclohexane (100 mL), butadiene (5.4 g, 100 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added, and the reaction was terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol, and the resulting polymer was dried under vacuum to constant weight to obtain polybutadiene elastomer.
[0128] Test results: Yield of polybutadiene elastomer: 98%, number average molecular weight (M n ): 4.2×10 5 g / mol, molecular weight distribution (PDI): 2.2; molar content of different structures in the elastomer: 1,4-structure accounts for 34%, 1,2-structure accounts for 66%, glass transition temperature is -7.2℃.
[0129] Example 23
[0130] A method for efficiently preparing polyβ-farnesene using an iron-based cycloborone catalytic system includes the following steps:
[0131] Under an argon atmosphere, anhydrous cyclohexane (100 mL), β-farnesene (20.4 g, 100 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added. The reaction was then terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol. The resulting polymer was dried under vacuum to constant weight to obtain polyβ-farnesene elastomer.
[0132] Test results: Yield of polyβ-farnesene elastomer: >99%, number average molecular weight (M n ): 4.7×10 5 g / mol, molecular weight distribution (PDI): 2.7; molar content of different structures in the elastomer: 1,4-structure accounts for 30%, 3,4-structure accounts for 70%, glass transition temperature is -8.4℃.
[0133] Example 24
[0134] A method for the efficient preparation of polymyrrhene using an iron-based cycloborone catalytic system includes the following steps:
[0135] Under an argon atmosphere, anhydrous cyclohexane (100 mL), myrcene (13.7 g, 100 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added. The reaction was then terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol. The resulting polymer was dried under vacuum to constant weight to obtain polymyrcene elastomer.
[0136] Test results: Yield of polymyrrhene elastomer: 99%, number average molecular weight (M n ): 8.0×10 5 g / mol, molecular weight distribution (PDI): 2.9; molar content of different structures in the elastomer: 1,4-structure accounts for 36%, 3,4-structure accounts for 64%, glass transition temperature is 4.4℃.
[0137] Example 25
[0138] A method for efficiently preparing polyconjugated dienes using an iron-based cycloboroxane catalytic system includes the following steps:
[0139] Under an argon atmosphere, anhydrous cyclohexane (100 mL), butadiene (1.62 g, 30 mmol), isoprene (4.76 g, 70 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added. The reaction was then terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol. The resulting polymer was dried under vacuum to constant weight to obtain the isoprene-butadiene copolymer elastomer.
[0140] Test results: Yield of isoprene-butadiene copolymer elastomer: >99%, number average molecular weight (M n ): 4.7×10 5 g / mol, molecular weight distribution (PDI): 2.4; the isoprene-butadiene copolymer elastomer has a polyisoprene molar content of 69%, of which 1,4-structure accounts for 29% and 3,4-structure accounts for 71%; the polybutadiene molar content is 31%, of which 1,4-structure accounts for 25% and 1,2-structure accounts for 75%; and the glass transition temperature is -1.2℃.
[0141] Example 26
[0142] A method for efficiently preparing polyconjugated dienes using an iron-based cycloboroxane catalytic system includes the following steps:
[0143] Under an argon atmosphere, anhydrous cyclohexane (100 mL), β-farnesene (6.12 g, 30 mmol), isoprene (4.76 g, 70 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added. The reaction was then terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol. The resulting polymer was dried under vacuum to constant weight to obtain the β-farnesene-isoprene copolymer elastomer.
[0144] Test results: Yield of β-farnesene-isoprene copolymer elastomer: >99%, number average molecular weight (M n ): 5.0×10 5 g / mol, molecular weight distribution (PDI): 3.2; the β-farnesene-isoprene copolymer elastomer has a polyisoprene molar content of 69%, of which 1,4-structure accounts for 33% and 3,4-structure accounts for 67%; the polyfarnesene molar content is 31%, of which 1,4-structure accounts for 32% and 3,4-structure accounts for 68%; and the glass transition temperature is -6.6℃.
[0145] Example 27
[0146] A method for efficiently preparing polyconjugated dienes using an iron-based cycloboroxane catalytic system includes the following steps:
[0147] Under an argon atmosphere, anhydrous cyclohexane (100 mL), myrcene (4.11 g, 30 mmol), isoprene (4.76 g, 70 mmol), triisobutylaluminum (79.3 mg, 0.4 mmol), N,N-bidentate carboxylic acid iron catalyst I (6.7 mg, 10 μmol), and cycloboronic alkane compound A (3.1 mg, 10 μmol) were added sequentially to a 250 mL Schlenk tube. Polymerization was carried out at 30 °C for 120 min. Then, 4 mL of a 1% (w / w) ethanol solution of 2,6-di-tert-butyl-4-methylphenol was added. The reaction was then terminated with a mixed solution of concentrated hydrochloric acid and methanol (methanol to concentrated hydrochloric acid volume ratio of 50:1). After discarding the supernatant, the polymer was washed three times with ethanol. The resulting polymer was dried under vacuum to constant weight to obtain the myrcene-isoprene copolymer elastomer.
[0148] Test results: Yield of myrcene-isoprene copolymer elastomer: 95%, number average molecular weight (M n ): 7.7×10 5 g / mol, molecular weight distribution (PDI): 2.4; the molar content of polyisoprene in the myrcene-isoprene copolymer elastomer is 65%, of which 1,4-structure accounts for 35% and 3,4-structure accounts for 65%; the molar content of polymyrcene is 35%, of which 1,4-structure accounts for 34% and 3,4-structure accounts for 66%; the glass transition temperature is -2.2℃.
[0149] Comparative Example 1
[0150] Polyisoprene was prepared according to the method of Example 1, except that the cycloboroxane compound A was replaced with [Ph3C]. + [B(CF5)4] - (9.2 mg, 10 μmol), other steps and parameters are the same as in Example 1.
[0151] Test results: Yield of polyisoprene elastomer: 98%, number average molecular weight (M n ): 5.6×10 5 g / mol, molecular weight distribution (PDI): 2.5; molar content of different structures in the elastomer: 1,4-structure accounts for 33%, 3,4-structure accounts for 67%, glass transition temperature is 3.5℃.
[0152] Cost comparison (cost of reaction raw materials required to produce one ton of polyisoprene): The cost of Comparative Example 1 is approximately RMB 2,000 / t, and the cost of Example 1 is approximately RMB 1,200 / t.
[0153] Comparative Example 1 and Example 1 demonstrate that cycloboroxane compounds exhibit the high activity of conventional boron salts while significantly reducing reaction costs, achieving a high-activity, low-cost reaction effect with significant industrial application potential. Observations show that the system after the reaction in Example 1 exhibits significantly better flowability and lower viscosity than the system after the reaction in Comparative Example 1, facilitating smooth dispensing and reducing the risk of sticking to the reactor.
[0154] Comparative Example 2
[0155] Polyisoprene was prepared according to the method of Example 1, except that the N,N-bidentate ferric carboxylate catalyst I was replaced with a pyridineimine ferrous chloride catalyst, with the following structural formula: The dosage was (3.1 mg, 10 μmol), and the other steps and parameters were the same as in Example 1.
[0156] Test results: No polymer formation. This is because catalytic activity is determined by the synergistic catalytic effect between different components in the catalytic system. In the epoxide catalytic system, epoxide borane compounds, together with alkylaluminum and iron carboxylate catalysts, more readily form iron metal active centers and have a stabilizing effect on these active centers, thus exhibiting high reactivity.
[0157] Comparative Example 3
[0158] Polyisoprene was prepared according to the method of Example 1, except that cycloboroxane compound A was not added to the catalytic system.
[0159] Test results: No polymer was generated. This is because it is difficult to generate iron metal active centers in the system, and the generated active centers are not stabilized and deactivated by cycloboronic alkane compounds. Therefore, the reaction system does not have catalytic activity.
[0160] The results from the above examples and comparative examples show that the method of preparing polyconjugated dienes using N,N-bident iron carboxylate catalyst, alkyl aluminum and cycloboroxane compounds as catalytic systems has higher reactivity, lower reaction cost and lower reaction fluidity, thereby improving the reaction yield of polyconjugated dienes while reducing production costs.
[0161] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for preparing polyconjugated dienes, characterized in that, The method includes: polymerizing a conjugated diene in the presence of an iron-based cycloboroxane catalytic system to obtain a polyconjugated diene; wherein the iron-based cycloboroxane catalytic system includes an N,N-bident iron carboxylate catalyst, alkyl aluminum, and cycloboroxane compounds; The N,N-bidentate ferric carboxylate catalyst is selected from one or more compounds having the following structural formulas: Among them, EHA is Naph is The general structural formula of the cycloboroxane compounds is: Wherein, R is a substituted or unsubstituted C2-C10 alkyl or a substituted or unsubstituted C6-C10 aryl.
2. The method according to claim 1, wherein, The cycloboroxane compounds are selected from one or more compounds having the following structural formulas:
3. The method according to claim 1 or 2, wherein, The alkylaluminum is selected from one or more of trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, triisobutylaluminum, and triisopropylaluminum.
4. The method according to claim 1 or 2, wherein, The molar ratio of boron in the boronoxane compound to iron in the N,N-bident carboxylic acid iron catalyst is (0.1-20):
1. And / or, the molar ratio of aluminum in the alkylaluminum to iron in the N,N-bident carboxylic acid iron catalyst is (1-100):1; And / or, the molar ratio of the conjugated diene to the iron element in the N,N-bident carboxylic acid iron catalyst is (5000-50000):
1.
5. The method according to claim 1 or 2, wherein, The conjugated diene is one or more of isoprene, butadiene, β-farnesene, and myrcene.
6. The method according to claim 1 or 2, wherein, The method specifically includes the following steps: Under anhydrous and oxygen-free conditions, conjugated dienes are polymerized in a solvent in the presence of an N,N-bidentate iron carboxylate catalyst, alkyl aluminum, and cycloboronic alkane compounds to obtain polyconjugated dienes.
7. The method according to claim 6, wherein, The polymerization reaction is carried out at a temperature of 0-100℃ for a time of 10-120 min. And / or, the polymerization reaction is carried out under stirring conditions, wherein the stirring speed is 100-1000 rpm; And / or, the volume ratio of the conjugated diene to the solvent is 1:(1-20).
8. The method according to claim 7, wherein, The polymerization reaction is carried out at a temperature of 30-60℃ for 30-120 minutes.
9. The method according to claim 6 or 7, wherein, The solvent is a non-polar solvent.
10. The method according to claim 9, wherein, The nonpolar solvent is selected from one or more of cyclohexane, n-hexane, petroleum ether, toluene, and xylene.
11. The method according to claim 6 or 7, wherein, The method further includes adding a quencher and an anti-aging agent after the polymerization reaction is completed.
12. The method according to claim 11, wherein, The volume ratio of the quenching agent to the solvent is 1:(10-100); And / or, the volume ratio of the anti-aging agent to the solvent is 1:(10-100).
13. The method according to claim 11 or 12, wherein, The quenching agent is a mixed solution of concentrated hydrochloric acid and methanol in a volume ratio of 1:50; And / or, the anti-aging agent is an ethanol solution of 2,6-di-tert-butyl-4-methylphenol with a mass concentration of 1-10%.