Binuclear ruthenium carbene catalyst as well as preparation method and application thereof

Abstract

The invention provides a binuclear ruthenium carbene catalyst and a preparation method and application thereof.The binuclear ruthenium carbene catalyst has the structure shown in the formula I. The binuclear ruthenium carbene complex has the advantages of being easy to synthesize, high in activity, small in catalyst dosage and high in stability, and can solve the problem that in cycloolefin metathesis polymerization reaction, an existing Grubbs catalyst is not prone to generating side reactions in the prior art. The problems of large catalyst dosage, low catalyst stability and the like exist.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of olefin metathesis catalysis, and relates to a binuclear ruthenium carbene catalyst and a preparation method and application thereof. BACKGROUND

[0002] Olefin metathesis reaction is one of the most important and most commonly used reaction types in organic chemistry, through metal-catalyzed reaction, the carbon-carbon double bond of two olefins can be broken and recombined into two new olefin structures, and high molecular materials can be prepared through olefin metathesis polymerization, so it has wide application in natural product and drug molecule synthesis, material science.

[0003] In the olefin metathesis catalyst system, the most commercialized, most practical and most widely used is Grubbs catalyst, which is a metal complex with ruthenium-carbene structure. In 1995, the first generation of Grubbs catalyst [RuCl2(=CHPh)(PCy3)2] has good stability to water and oxygen, and good functional group tolerance to reaction substrates. In 1999, on the basis of the first generation of catalyst, one PCy3 ligand was replaced with an N-heterocyclic carbene ligand to develop the second generation of Grubbs catalyst [(H2IMes)(PCy3)RuCl2(=CHPh)], which not only has the advantages of the first generation of catalyst, but also greatly improves the reaction activity of the metal catalyst, and is widely used in the fields of drug and material industry.

[0004] Although the current ruthenium-based olefin metathesis catalysts have shown high catalytic performance in many fields, there are still many problems, such as high catalyst dosage, wide molecular weight of polymerization products, etc. Transition metal carbene complexes have attracted great research interest due to their unique structure, reaction characteristics and application in organic synthesis and catalytic reaction. Through the research of previous literatures, we found that the synthesis of ruthenium carbene catalysts is basically through the change of ligand and the change of atoms coordinated with the central atom ruthenium to improve the catalytic efficiency, universality, stability, recyclability and other properties of the catalyst.

[0005] In the study of olefin polymerization, the strategy of binuclear metal catalyst has a significant influence on the polymerization process and polymerization products. CN 109692709A discloses a chiral phosphinoamine binuclear ruthenium carbene complex structure catalyst, which shows high catalytic activity in olefin metathesis reaction. CN120081790A discloses a binuclear ruthenium catalyst with bridged bis-nitrogen heterocyclic carbene ligand, which is used for the ring-opening metathesis polymerization of dicyclopentadiene. However, the synthesis of the ligands of the above two catalysts is relatively complex, thus limiting their application.

[0006] Based on this, the application aims to provide a binuclear ruthenium carbene catalyst and a preparation method and application thereof. SUMMARY

[0007] In view of the deficiencies of the prior art, the application aims to provide a binuclear ruthenium carbene catalyst and a preparation method and application thereof. The binuclear ruthenium carbene complex of the application has the advantages of simple synthesis, high activity, small amount of catalyst and high stability, and can solve the problems of the existing Grubbs catalyst, such as large amount of catalyst and low stability of the catalyst in the ring-opening metathesis polymerization reaction of cycloolefins.

[0008] To achieve the above-mentioned purpose, the application adopts the following technical solutions.

[0009] In one aspect, the application provides a binuclear ruthenium carbene catalyst, which has the structure shown in Formula I:

[0010] ;

[0011] wherein R is a C6-C18 cycloalkyl, an alkane or a C6-C18 aromatic hydrocarbon group; n is an integer of 1-6 (for example, 1, 2, 3, 4, 5 or 6); and Ph represents a phenyl group.

[0012] NHC is a nitrogen-containing five-membered ring carbene, and its structural formula is shown in Formula II, wherein the position of the lone pair of electrons is the coordination position with the metal Ru.

[0013] .

[0014] Preferably, the binuclear ruthenium carbene catalyst is any one of the following compounds:

[0015] ;

[0016] wherein Cy represents a cyclohexyl group, Mes represents , and the wavy line represents the connection site of the group.

[0017] In another aspect, the application provides a preparation method of the binuclear ruthenium carbene catalyst as described above, which comprises the following steps:

[0018] (1) Under the protection of an inert gas, compound 1 is subjected to a substitution reaction with pyridine to obtain a ruthenium carbene complex 2 coordinated with pyridine, and the reaction formula is as follows:

[0019] ;

[0020] (2) Under the protection of an inert gas, compound 2 is subjected to a substitution reaction with compound 3 to obtain the binuclear ruthenium carbene catalyst shown in Formula I, and the reaction formula is as follows:

[0021] .

[0022] Preferably, the inert gas in step (1) is nitrogen or argon.

[0023] Preferably, the amount of pyridine used in step (1) is 2-20 L, preferably 5 L, relative to 1 mol of compound 1.

[0024] Preferably, the pyridine in step (1) is anhydrous pyridine.

[0025] Preferably, the reaction temperature of the substitution reaction in step (1) is room temperature, i.e. 15-35°C, such as 15°C, 18°C, 20°C, 25°C, 28°C, 30°C, 33°C or 35°C.

[0026] Preferably, the time of the substitution reaction in step (1) is 2-10 h, such as 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h or 10 h, preferably 5 h.

[0027] Preferably, the substitution reaction in step (1) is carried out under stirring.

[0028] Preferably, after the substitution reaction in step (1), the following post-treatment steps are further included: precipitation (preferably using petroleum ether), filtration, washing (preferably using petroleum ether) and drying (preferably vacuum drying).

[0029] Preferably, the inert gas in step (2) is nitrogen.

[0030] Preferably, the molar ratio of compound 2 to compound 3 in step (2) is 2:1.

[0031] Preferably, the substitution reaction in step (2) is carried out in an organic solvent.

[0032] Preferably, the organic solvent is one or a combination of at least two of dichloromethane, 1,2-dichloroethane, tetrahydrofuran, toluene or dioxane.

[0033] Preferably, the amount of organic solvent used is 0.5-10 L, such as 0.5 L, 1 L, 2 L, 3 L, 4 L, 5 L, 6 L, 7 L, 8 L, 9 L or 10 L, preferably 2-8 L, relative to 1 mol of compound 2.

[0034] Preferably, the reaction temperature of the substitution reaction in step (2) is room temperature, i.e. 15-35°C, such as 15°C, 18°C, 20°C, 25°C, 28°C, 30°C, 33°C or 35°C.

[0035] Preferably, the time of the substitution reaction in step (2) is 1 h to 5 h, such as 1 h, 2 h, 3 h, 4 h or 5 h, preferably 2 h.

[0036] Preferably, after the substitution reaction of step (2) ends, the following post-treatment steps are further included: precipitation (preferably using petroleum ether to precipitate), filtration, washing (preferably using petroleum ether to wash), and drying (preferably vacuum drying).

[0037] In another aspect, the present application provides the use of the dinuclear ruthenium carbene catalyst as described above in catalyzing the ring-opening metathesis polymerization of cyclic olefins.

[0038] Preferably, the cyclic olefin includes, but is not limited to, at least one of dicyclopentadiene, tricyclopentadiene, norbornene, norbornadiene, or cyclooctadiene.

[0039] Preferably, the use specifically includes the following steps:

[0040] The dinuclear ruthenium carbene catalyst is dissolved in an organic solvent to obtain a solution A, the cyclic olefin monomer and optional functional additives are mixed uniformly to obtain a solution B, and the solution A and the solution B are thoroughly mixed to undergo the ring-opening metathesis polymerization.

[0041] Preferably, the organic solvent in the use is selected from one of dichloromethane, dichloroethane, toluene, xylene, or tetrahydrofuran, or a mixture of at least two thereof.

[0042] Preferably, the molar ratio of the cyclic olefin monomer to the ruthenium carbene catalyst is 5000-200000:1, for example, 5000:1, 6000:1, 8000:1, 9000:1, 10000:1, 30000:1, 50000:1, 80000:1, 100000:1, 130000:1, 150000:1, 180000:1, or 200000:1.

[0043] Preferably, the temperature of the ring-opening metathesis polymerization is 30-100℃, for example, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, 90℃, or 100℃, and the reaction time is 0.1-10 h, for example, 0.1 h, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, or 10 h.

[0044] In the present application, in the use, the solution A and the solution B are thoroughly mixed, and then immediately injected into a mold to undergo the ring-opening metathesis polymerization, solidification molding, and removal of the mold.

[0045] Compared with the prior art, the present application has the following beneficial effects:

[0046] The dinuclear ruthenium carbene catalyst of the present application has the advantages of high catalytic activity, low catalyst dosage, and high stability in the ring-opening metathesis polymerization of cyclic olefins. DETAILED DESCRIPTION

[0047] The technical solutions of the present application are further illustrated below by specific embodiments. Those skilled in the art should understand that the embodiments are only used to help understand the present application and should not be regarded as specific limitations of the present application.

[0048] Example 1

[0049] This example provides a method for preparing a binuclear ruthenium carbene complex Ru-1

[0050]

[0051] Under nitrogen protection, a dry 250 mL single-neck flask equipped with a magnetic stirrer was charged with 8.49 g of ruthenium compound 1, and then 50 mL of anhydrous pyridine was added. The reaction was stirred at room temperature for 2.0 h. The solution turned dark green, and the stirring was stopped. The reaction mixture was added dropwise into a beaker containing 200 mL of petroleum ether, and the stirring was continuously intensified. During this process, green precipitate slowly separated from the reaction solution. After the reaction was completed, the reaction solution was filtered to obtain green solid. The solid was washed with petroleum ether three times, and was dried under vacuum to obtain green intermediate product 2, weighing 6.5 g, with a yield of 89.4%.

[0052] NMR characterization data: 1 H NMR (500MHz, CDCl3): 19.18 (s, 1H), 8.63 (s, 2H), 7.83(s, 2H), 7.67 (t, 1H), 7.63 (d, 2H), 7.48 (t, 2H), 7.27 (m, 2H), 7.06-7.09(m, 4H), 6.97 (s, 2H), 6.75 (s, 2H), 4.12 (br d, 4H, NCH2CH2N), 2.65 (s, 6H),2.24-2.36 (m, 12H).

[0053]

[0054] Under nitrogen protection, a dry 250 mL single-neck flask equipped with a magnetic stirrer was charged with 8.49 g of ruthenium compound 1, and then 50 mL of anhydrous pyridine was added. The reaction was stirred at room temperature for 2.0 h. The solution turned dark green, and the stirring was stopped. The reaction mixture was added dropwise into a beaker containing 200 mL of petroleum ether, and the stirring was continuously intensified. During this process, green precipitate slowly separated from the reaction solution. After the reaction was completed, the reaction solution was filtered to obtain green solid. The solid was washed with petroleum ether three times, and was dried under vacuum to obtain green intermediate product 2, weighing 6.5 g, with a yield of 89.4%.

[0055] NMR characterization data:

[0056] 1 H NMR (500 MHz, CDCl3): δ 19.67 (s, 2H), 7.35 (br s, 4H), 7.22 (br s,4H), 7.15-6.65 (m, 26H), 6.67 (br s, 4H), 4.02-3.88 (m, 8H), 2.51 (s, 12H), 2.31 (s, 6H), 2.17 (s, 12H), 1.91 (s, 6H), 1.75-1.57 (m, 6H) ppm.

[0057] 31 P NMR (203 MHz, CDCl3): 28.58 ppm.

[0058] Example 2

[0059] This embodiment provides a method for preparing a binuclear ruthenium carbene complex Ru-2.

[0060]

[0061] 1.47 g (2.0 mmol) of complex 2,426 mg (1.0 mmol) of 1,4-bis(diphenylphosphine)butane was added sequentially to a dry 100 mL reaction vessel equipped with a stir bar. After purging with nitrogen three times, 20 mL of dry dichloromethane was added, and the mixture was stirred at room temperature for 2 h. During this process, the solution gradually changed from green to brownish-red. After the reaction was complete, the solvent was removed by rotary evaporation, and 20 mL of petroleum ether was added to precipitate the solid. The solid was filtered through a sintered glass funnel, washed with petroleum ether 10 mL × 3 times, and dried under vacuum to give a brown solid product Ru-2, weighing 0.97 g, with a yield of 62%.

[0062] NMR characterization data:

[0063] 1 H NMR (500 MHz, CDCl3): δ 19.67 (s, 2H), 7.36 (br s, 4H), 7.21 (br s,4H), 7.15-6.65 (m, 26H), 6.67 (br s, 4H), 4.02-3.88 (m, 8H), 2.52 (s, 12H), 2.31 (s, 6H), 2.18 (s, 12H), 1.92 (s, 6H), 1.75-1.57 (m, 8H) ppm.

[0064] 31 P NMR (203 MHz, CDCl3): 28.62 ppm.

[0065] Example 3

[0066] This embodiment provides a method for preparing a binuclear ruthenium carbene complex Ru-3.

[0067]

[0068] 1.47 g (2.0 mmol) of complex 2,426 mg (1.0 mmol) of 1,4-bis(dicyclohexylphosphine)butane was added sequentially to a dry 100 mL reaction vessel equipped with a stir bar. After purging with nitrogen three times, 20 mL of dry dichloromethane was added, and the mixture was stirred at room temperature for 2 h. During this process, the solution gradually changed from green to brownish-red. After the reaction was complete, the solvent was removed by rotary evaporation, and 20 mL of petroleum ether was added to precipitate the solid. The solid was filtered through a sintered glass funnel, washed with petroleum ether 10 mL × 3 times, and dried under vacuum to give a brown solid product Ru-3, weighing 1.24 g, with a yield of 78%.

[0069] NMR characterization data:

[0070] 1 H NMR (500 MHz, CDCl3): δ 19.67 (s, 2H), 7.36-7.31 (m, 2H), 7.10-6.95(m, 12H), 6.50 (br s, 4H), 4.06-3.84 (m, 8H), 2.52 (s, 12H), 2.31 (s, 6H), 2.18 (s, 12H), 1.98 (s, 6H), 1.95-1.70 (m, 22H), 1.60-0.75 (m, 30H) ppm.

[0071] 31 P NMR (203 MHz, CDCl3): 27.85 ppm.

[0072] Example 4

[0073] This embodiment provides a method for preparing the binuclear ruthenium carbene complex Ru-4.

[0074]

[0075] 1.47 g (2.0 mmol) of complex 2,426 mg (1.0 mmol) of 1,5-bis(diphenylphosphine)pentane was added sequentially to a dry 100 mL reaction vessel equipped with a stir bar. After purging with nitrogen three times, 20 mL of dry dichloromethane was added, and the mixture was stirred at room temperature for 2 h. During this process, the solution gradually changed from green to brownish-red. After the reaction was complete, the solvent was removed by rotary evaporation, and 20 mL of petroleum ether was added to precipitate the solid. The solid was filtered through a sintered glass funnel, washed with petroleum ether 10 mL × 3 times, and dried under vacuum to give a brown solid product Ru-4, weighing 1.1 g, with a yield of 70%.

[0076] NMR characterization data:

[0077] 1 H NMR (500 MHz, CDCl3): 1 H NMR (500 MHz, CDCl3): δ 19.67 (s, 2H), 7.36 (br s, 4H), 7.21 (br s, 4H), 7.15-6.64 (m, 26H), 6.68 (br s, 4H), 4.01-3.87 (m, 8H), 2.52 (s, 12H), 2.31 (s, 6H), 2.18 (s, 12H), 1.92 (s, 6H), 1.78-1.56 (m, 10H) ppm.

[0078] 31 P NMR (203 MHz, CDCl3): 28.56 ppm.

[0079] Examples 5-8

[0080] Applications of binuclear ruthenium carbene complexes in the ring-opening metathesis polymerization of cyclic olefins

[0081] Taking the complex Ru-1 as an example, a dicyclopentadiene catalytic ring-opening metathesis polymerization reaction was carried out, with a monomer to catalyst molar ratio of 100,000:1.

[0082] (1) Prepare catalyst feed solution A

[0083] Weigh 310 mg (0.2 mmol) of the ruthenium carbene catalyst Ru-1 prepared in Example 1 in a glove box, and dissolve it in 30 mL of 1,2-dichloroethane to prepare a catalyst solution of 10 mg / mL.

[0084] (2) Prepare dicyclopentadiene feed solution B

[0085] Dicyclopentadiene (purity greater than 98%) was stirred at 40°C under nitrogen protection, and 3% (by weight) of triphenylphosphine was added and fully dissolved in advance to obtain dicyclopentadiene solution B, which was then stored under nitrogen at 30-40°C.

[0086] (3) Mixing and curing molding

[0087] Measure 4 ml of solution A and 300 g of solution B to make the molar ratio of dicyclopentadiene to catalyst 100000:1. Mix solution A and solution B rapidly under nitrogen protection. After mixing evenly, quickly pour the mixture into a reaction mold and cure at 80°C for 1 h to obtain a polydicyclopentadiene material sample.

[0088] Comparative Example 1

[0089] The difference between this comparative example and Example 5 is that the binuclear ruthenium carbene complex is replaced with a Grubbs II catalyst, and the molar ratio of monomer to catalyst is 50,000:1, while all other aspects are the same.

[0090] Comparative Example 2

[0091] The difference between this comparative example and Example 5 is that the binuclear ruthenium carbene complex is replaced with the catalyst shown in Formula A below, and the molar ratio of monomer to catalyst is 100,000:1. All other aspects are the same as in Example 5.

[0092] .

[0093] The polydicyclopentadiene material samples provided in the embodiments and comparative examples of the present invention were processed to obtain specimens that meet the performance tests of polydicyclopentadiene resin. Mechanical property tests were then conducted using the following methods:

[0094] (1) Tensile strength and tensile modulus: tested in accordance with GB / T 2567-2021;

[0095] (2) Bending strength and bending modulus: tested in accordance with GB / T 2567-2021.

[0096] The performance test results are shown in Table 1.

[0097] Table 1

[0098]

[0099] Catalysts Ru-1, Ru-2, Ru-3, and Ru-4 are bimetallic catalysts with two metal active sites, and the amount of catalyst used is reduced by half compared to single-active-site catalysts. According to the results shown in Table 2, compared to the Grubbs II catalyst, the polymers obtained by polymerization using the catalysts provided in this application exhibit improved mechanical properties such as tensile strength, flexural strength, and flexural modulus.

[0100] The applicant declares that this invention illustrates the binuclear ruthenium carbene catalyst, its preparation method, and its application through the above embodiments. However, this invention is not limited to the above embodiments, meaning that this invention does not necessarily rely on the above embodiments for implementation. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product, additions of auxiliary components, and selection of specific methods all fall within the protection and disclosure scope of this invention.

Claims

1. A dinuclear ruthenium carbene catalyst characterized by, The binuclear ruthenium carbene catalyst has a structure shown in formula I: ； wherein R is a C6-C18 cycloalkyl, a C4-C18 alkyl or a C6-C18 aromatic hydrocarbon group; n is an integer of 1-6; and Ph represents a phenyl group; NHC is a nitrogen-containing five-membered ring carbene, and its structural formula is shown in formula II, wherein the position of the lone pair of electrons is the coordination position with the metal Ru; 。 2. The dinuclear ruthenium carbene catalyst of claim 1, wherein, The binuclear ruthenium carbene catalyst is any one of the following compounds: ； wherein Cy represents a cyclohexyl group, Mes represents , the wavy line represents the point of attachment of the group.

3. A process for the preparation of the dinuclear ruthenium carbene catalyst according to claim 1 or 2, characterized in that, The preparation method comprises the following steps: (1) under the protection of inert gas, compound 1 is subjected to a substitution reaction with pyridine to obtain a pyridine-coordinated ruthenium carbene complex 2, and the reaction formula is as follows: ； (2) under the protection of inert gas, compound 2 is subjected to a substitution reaction with compound 3 to obtain the binuclear ruthenium carbene catalyst shown in formula I, and the reaction formula is as follows: 。 4. The production method according to claim 3, characterized by, In step (1), the inert gas is nitrogen or argon; Preferably, in step (1), the amount of pyridine used is 2-20 L, preferably 5 L, relative to 1 mol of compound 1; Preferably, in step (1), the pyridine is anhydrous pyridine; Preferably, in step (1), the reaction temperature of the substitution reaction is room temperature; Preferably, in step (1), the time of the substitution reaction is 2-10 h, preferably 5 h; Preferably, in step (1), the substitution reaction is carried out under stirring; Preferably, after the substitution reaction in step (1) is completed, the following post-treatment steps are further included: precipitation, filtration, washing and drying.

5. The production method according to claim 3, characterized by, In step (2), the inert gas is nitrogen; Preferably, in step (2), the molar ratio of compound 2 to compound 3 is 2:

1.

6. The preparation method according to claim 3, characterized in that, In step (2), the substitution reaction is carried out in an organic solvent; Preferably, the organic solvent is one or a combination of at least two of dichloromethane, 1,2-dichloroethane, tetrahydrofuran, toluene or dioxane; Preferably, the amount of the organic solvent used is 0.5-10 L, preferably 2-8 L, relative to 1 mol of compound 2.

7. The preparation method according to claim 3, characterized in that, In step (2), the reaction temperature of the substitution reaction is room temperature; Preferably, in step (2), the time of the substitution reaction is 1-5 h, preferably 2 h; Preferably, after the substitution reaction in step (2) is completed, the following post-treatment steps are further included: precipitation, filtration, washing and drying.

8. Use of the binuclear ruthenium carbene catalyst according to claim 1 or 2 in catalyzing a ring-opening metathesis polymerization reaction of a cyclic olefin.

9. Use according to claim 8, characterized in that, The cyclic olefin includes but is not limited to at least one of dicyclopentadiene, tricyclopentadiene, norbornene, norbornadiene or cyclooctadiene.

10. Use according to claim 8, characterized in that, The use specifically comprises the following steps: The binuclear ruthenium carbene catalyst is dissolved in an organic solvent to obtain a solution A, a cyclic olefin monomer and optionally a functional additive are uniformly mixed to obtain a solution B, and the solution A and the solution B are thoroughly mixed to occur a ring-opening metathesis polymerization reaction; Preferably, in the use, the organic solvent is selected from one or a mixture of at least two of dichloromethane, dichloroethane, toluene, xylene or tetrahydrofuran; Preferably, the molar ratio of the cyclic olefin monomer to the ruthenium carbene catalyst is 5000-200000:

1. Preferably, the temperature of the ring-opening metathesis polymerization reaction is 30-100°C, and the reaction time is 0.1-10 h.

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