A cobalt phosphine catalyst, its preparation method and application

Abstract

This invention discloses a cobalt-phosphine catalyst, its preparation method, and its applications, relating to the field of catalyst organic synthesis technology. The catalyst is prepared by a complexation reaction of a cobalt catalytic precursor and a ligand; wherein the cobalt catalytic precursor is cobalt octacarbonyl, cobalt triacetylacetonate, cobalt diacetylacetonate, cobalt chloride, cobalt bromide, cobalt iodide, or cobalt trifluoromethanesulfonate. The catalyst of this invention is highly efficient and economical; the reaction proceeds smoothly under low pressure, and olefin substrates can be selectively converted into straight-chain esters under this catalytic system. For terminal alkyne substrates, the diester selection of the product is high. Simultaneously, the catalytic system exhibits good stability and can undergo multiple cycle experiments. This invention solves the problems of resource scarcity, high cost, and difficulty in recycling faced by existing technologies using precious metal catalysts.

Description

Technical Field

[0001] This invention relates to the field of catalyst organic synthesis technology, specifically to a cobalt phosphine catalyst, its preparation method, and its application. Background Technology

[0002] Hydrogen esterification is an atomically efficient process catalyzed by transition metals, involving unsaturated bonds, carbon monoxide, and alcohols to produce esters. It enables the insertion of carbonyl groups into small molecule compounds and the construction of novel C-C bonds. Hydrogen esterification has wide applications in chemical raw material utilization and drug development, and its target products are crucial intermediates in organic synthesis. For example, the 1,4-dicarboxylic acid esters and their derivatives obtained from the diesterization of alkynes are important intermediates in biochemistry and materials science. They can be used to prepare high-value-added products such as renin inhibitors, matrix metalloproteinase inhibitors, biomaterials, and polymers.

[0003] Currently, reported hydrogen esterification reactions of olefins and alkynes typically use noble metal catalysts such as rhodium and palladium. However, due to the scarcity of noble metals and the growing demand for sustainable development, cost-effective and globally abundant inexpensive metals hold promise as ideal alternatives, especially for homogeneous catalysts that are difficult to recycle. Cobalt catalysts have come into focus due to their abundant global resources and economic viability; however, they face challenges such as low reactivity and the need for stringent reaction conditions to form the key cobalt hydride catalytically active species. Therefore, a new cobalt catalyst is urgently needed. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a cobalt phosphine catalyst, its preparation method, and its applications. This addresses the issues of resource scarcity, high cost, and difficulty in recycling encountered in the prior art when using precious metal catalysts for hydrogen esterification.

[0005] The technical solution of this invention to solve the above-mentioned technical problems is as follows: A cobalt phosphine catalyst is provided, which is prepared by a complexation reaction of a cobalt catalytic precursor and a ligand; wherein the cobalt catalytic precursor is cobalt octacarbonyl, cobalt triacetylacetonate, cobalt diacetylacetonate, cobalt chloride, cobalt bromide, cobalt iodide, or cobalt trifluoromethanesulfonate; the molecular structural formula of the ligand is:

[0006] Based on the above technical solution, the present invention can be further improved as follows:

[0007] The present invention also provides a method for preparing the above-mentioned cobalt phosphine catalyst, comprising the following steps:

[0008] (1) Add the cobalt catalytic precursor and ligand to an organic solvent and react under carbon monoxide conditions for 4-36 h to obtain a reaction solution;

[0009] (2) The reaction solution in step (1) was allowed to stand, the pressure was released, and then the solution was filtered and washed under reduced pressure to obtain the cobalt phosphine catalyst.

[0010] Furthermore, in step (1), the molar ratio of the cobalt catalytic precursor to the ligand is 1:1-2; the molar volume ratio of the ligand to the organic solvent is 1 mmol:1-2 mL.

[0011] In step (1), the molar ratio of cobalt catalytic precursor to ligand is 1:1; the molar volume ratio of ligand to organic solvent is 1 mmol: 1 mL.

[0012] In step (1), the molar ratio of cobalt catalytic precursor to ligand is 1:1; the molar volume ratio of ligand to organic solvent is 1 mmol: 2 mL.

[0013] Furthermore, in step (1), the organic solvent is methanol.

[0014] Furthermore, in step (1), the carbon monoxide pressure is 0.5-5 MPa.

[0015] Furthermore, in step (1), the pressure is 4 MPa.

[0016] Furthermore, in step (1), the reaction is carried out at 80-140℃.

[0017] Furthermore, in step (1), the reaction is carried out at 120°C.

[0018] Furthermore, in step (2), let it stand for 10-24 hours.

[0019] Furthermore, in step (2), the mixture is left to stand for 20 hours.

[0020] Furthermore, in step (2), the mixture is left to stand at room temperature.

[0021] Furthermore, in step (2), washing is performed using diethyl ether, dichloromethane, or ethyl acetate.

[0022] The present invention also provides the application of the above-mentioned cobalt phosphine catalyst in the hydrogen esterification reaction of unsaturated hydrocarbons.

[0023] Furthermore, the above application method is as follows: adding a cobalt phosphine catalyst to the hydrogen esterification reaction of unsaturated hydrocarbons to carry out the catalytic reaction; or simultaneously adding a cobalt catalytic precursor, ligand, methanol and carbon monoxide to unsaturated hydrocarbons to carry out an in-situ catalytic reaction.

[0024] Furthermore, in both catalytic and in-situ catalytic reactions, the unsaturated hydrocarbons are alkenes or alkynes.

[0025] Furthermore, during the catalytic reaction, the molar ratio of unsaturated hydrocarbons to cobalt phosphine catalyst is 20-100:1.

[0026] Furthermore, during the catalytic reaction, the molar ratio of unsaturated hydrocarbons to cobalt phosphine catalyst is 20:1.

[0027] Furthermore, the catalytic reaction was carried out under conditions of carbon monoxide pressure of 3-5 MPa, solvent methanol, and 100-140 °C.

[0028] Furthermore, the catalytic reaction was carried out under the conditions of carbon monoxide pressure of 4 MPa, solvent methanol, and 120 °C.

[0029] Furthermore, during the in-situ catalytic reaction, the molar ratio of unsaturated hydrocarbons to the in-situ generated cobalt phosphine catalyst is 20-100:1.

[0030] Furthermore, during the in-situ catalytic reaction, the molar ratio of unsaturated hydrocarbons to the in-situ generated cobalt phosphine catalyst is 20:1.

[0031] Furthermore, the in-situ catalytic reaction was carried out under conditions of carbon monoxide pressure of 3-5 MPa, solvent methanol, and 100-140 °C.

[0032] Furthermore, an in-situ catalytic reaction was carried out under conditions of 4 MPa carbon monoxide pressure, methanol solvent, and 120 °C.

[0033] The present invention has the following beneficial effects:

[0034] 1. This invention modifies the cobalt catalyst with corresponding ligands. The unique properties of the modified cobalt phosphine catalyst enable the diesterization of alkynes with high activity and high selectivity under mild conditions, and it has good stability and can be subjected to multiple cycle experiments.

[0035] 2. The catalyst of this invention is highly efficient and economical. The reaction can proceed smoothly under low pressure, and olefin substrates can be selectively converted into straight-chain esters under this catalytic system. For terminal alkyne substrates, the diester selection of the product is high. At the same time, the catalytic system has good stability and can be subjected to multiple recycling experiments. This invention solves the problems of resource scarcity, high price, and difficulty in recycling faced by existing technologies using precious metal catalysts. Attached Figure Description

[0036] Figure 1 The 1H NMR spectrum of the cobalt phosphine catalyst prepared in Example 1;

[0037] Figure 2 The phosphorus NMR spectrum of the cobalt phosphine catalyst prepared in Example 1;

[0038] Figure 3The image shows the Ortep diagram of the single crystal of the cobalt phosphine catalyst prepared in Example 1.

[0039] Figure 4 The 1H NMR spectrum of the target product 2-phenylsuccinate dimethyl ester in Example 6;

[0040] Figure 5 The carbon NMR spectrum of the target product 2-phenylsuccinate dimethyl ester in Example 6. Detailed Implementation

[0041] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0042] In the following example, the molecular structure of ligand L1 is: Example 1:

[0043] A cobalt phosphine catalyst, the preparation method of which includes the following steps:

[0044] (1) In a high-temperature reactor, 10 mmol of cobalt catalyst precursor octacarbonyl dicobalt (Co2(CO)8) and 10 mmol of ligand L1 were added to 10 mL of organic solvent methanol. Then carbon monoxide gas was introduced to form a pressure condition. The reaction was carried out at 120 °C for 20 h under a pressure of 4 MPa to obtain a reaction solution.

[0045] (2) The reaction solution from step (1) was allowed to stand at room temperature for 20 hours to allow the complex to crystallize from the mother liquor. The pressure in the reactor was slowly released, and then the mixture was filtered under reduced pressure and washed with diethyl ether to obtain orange crystals, which are the cobalt phosphine catalyst (cobalt phosphine complex [Co(CO)3(L1)]). + [Co(CO)4] - ).

[0046] The reaction formula is as follows:

[0047]

[0048] Example 2:

[0049] A cobalt phosphine catalyst, the preparation method of which includes the following steps:

[0050] (1) In a high-temperature reactor, 0.05 mmol of cobalt catalyst precursor octacarbonyl dicobalt (Co2(CO)8) and 0.075 mmol of ligand L1 were added to 0.1 mL of organic solvent methanol. Then, carbon monoxide gas was introduced to form a pressure condition. The reaction was carried out at 80 °C for 36 h under a pressure of 0.5 MPa to obtain a reaction solution.

[0051] (2) The reaction solution from step (1) was allowed to stand at room temperature for 10 hours to allow the complex to crystallize from the mother liquor. The pressure in the reactor was slowly released, and then the mixture was filtered under reduced pressure and washed with dichloromethane to obtain orange crystals, which are the cobalt phosphine catalyst (cobalt phosphine complex [Co(CO)3(L1)]). + [Co(CO)4] - ).

[0052] Example 3:

[0053] A cobalt phosphine catalyst, the preparation method of which includes the following steps:

[0054] (1) In a high-temperature reactor, 1 mmol of cobalt catalyst precursor octacarbonyl dicobalt (Co2(CO)8) and 2 mmol of ligand L1 were added to 4 mL of organic solvent methanol. Then carbon monoxide gas was introduced to form a pressure condition. The reaction was carried out at 140 °C for 4 h under a pressure of 5 MPa to obtain a reaction solution.

[0055] (2) The reaction solution from step (1) was allowed to stand at room temperature for 24 hours to allow the complex to crystallize from the mother liquor. The pressure in the reactor was slowly released, and then the mixture was filtered under reduced pressure and washed with ethyl acetate to obtain orange crystals, which are the cobalt phosphine catalyst (cobalt phosphine complex [Co(CO)3(L1)]). + [Co(CO)4] - ).

[0056] Example 4:

[0057] A cobalt phosphine catalyst, the preparation method of which includes the following steps:

[0058] (1) In a high-temperature reactor, 1 mmol of cobalt catalytic precursor cobalt chloride (CoCl2) and 1 mmol of ligand L1 were added to 2 mL of organic solvent methanol. Then, carbon monoxide gas was introduced to form a pressure condition. The reaction was carried out at 135 °C for 36 h under a pressure of 4.5 MPa to obtain a reaction solution.

[0059] (2) The reaction solution in step (1) was allowed to stand at room temperature for 20 hours to allow the complex to crystallize from the mother liquor. The pressure in the reactor was slowly released, and then the solution was filtered under reduced pressure and washed with ether to obtain orange crystals, namely cobalt phosphine catalyst (cobalt phosphine complex Co(CO)3(L1)).

[0060] The reaction formula is as follows:

[0061]

[0062] Example 5:

[0063] A cobalt phosphine catalyst, the preparation method of which includes the following steps:

[0064] (1) In a high-temperature reactor, 1 mmol of cobalt catalytic precursor cobalt diacetylacetonate (Co(acac)2) and 1 mmol of ligand L1 were added to 2 mL of organic solvent methanol. Then, carbon monoxide gas was introduced to form a pressure condition. The reaction was carried out at 110 °C for 24 h under a pressure of 3 MPa to obtain a reaction solution.

[0065] (2) The reaction solution in step (1) was allowed to stand at room temperature for 20 hours to allow the complex to crystallize from the mother liquor. The pressure in the reactor was slowly released, and then the solution was filtered under reduced pressure and washed with ether to obtain orange crystals, namely cobalt phosphine catalyst (cobalt phosphine complex Co(CO)3(L1)).

[0066] The reaction formula is as follows:

[0067]

[0068] In practical applications, the cobalt phosphine catalyst of the present invention can be prepared first and then used for catalytic reaction; alternatively, the substrate and the raw materials for preparing the catalyst can be added simultaneously for in-situ catalytic reaction, as illustrated below.

[0069] Example 6:

[0070] The method of applying a cobalt phosphine catalyst to the hydrogen esterification reaction of alkynes includes the following steps:

[0071] (1) Combine 1 mmol of phenylacetylene and 0.05 mmol of cobalt phosphine complex [Co(CO)3(L1)] + [Co(CO)4] - (The cobalt phosphine catalyst prepared in Example 1), 2 mL of methanol, were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reactor was reacted at 120 °C for 4 h to obtain a reaction solution.

[0072] (2) After the reaction was completed, the reactor was allowed to cool to room temperature and the pressure was slowly released to separate and purify the mixture. Then, the mixture was separated by column chromatography (PE:EA = 20:1) to obtain 0.56 mmol of the target product 2-phenylsuccinate dimethyl ester.

[0073] The reaction formula is as follows:

[0074]

[0075] Example 7:

[0076] The method of applying a cobalt phosphine catalyst to the hydrogen esterification reaction of alkynes includes the following steps:

[0077] (1) 1 mmol phenylacetylene, 0.01 mmol cobalt phosphine complex Co(CO)3(L1) (cobalt phosphine catalyst prepared in Example 4), and 2 mL methanol were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reaction was carried out at 120 °C for 4 h to obtain a reaction solution.

[0078] (2) After the reaction was completed, the reactor was allowed to cool to room temperature and the pressure was slowly released to separate and purify the mixture. Then, the mixture was separated by column chromatography (PE:EA = 20:1) to obtain 0.60 mmol of the target product 2-phenylsuccinate dimethyl ester.

[0079] The reaction formula is as follows:

[0080]

[0081] Example 8:

[0082] The method for applying a cobalt phosphine catalyst to the hydrogen esterification reaction of olefins includes the following steps:

[0083] (1) 1 mmol styrene, 0.05 mmol cobalt catalyst precursor Co(OTf)2, 0.05 mmol ligand L1 and 2 mL methanol were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reaction was carried out at 120 °C for 20 h to obtain a reaction solution.

[0084] (2) After the reaction was completed, the reactor was allowed to cool to room temperature and the pressure was slowly released to separate and purify the mixture. Then, the mixture was separated by column chromatography (PE:EA = 50:1) to obtain 0.71 mmol of the target product methyl 3-phenylpropionate.

[0085] The reaction formula is as follows:

[0086]

[0087] Example 9:

[0088] The method for applying a cobalt phosphine catalyst to the hydrogen esterification reaction of olefins includes the following steps:

[0089] (1) 1 mmol phenylacetylene, 0.01 mmol cobalt catalytic precursor Co(acac)2, 0.01 mmol ligand L1 and 2 mL methanol were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reaction was carried out at 120 °C for 4 h to obtain a reaction solution.

[0090] (2) After the reaction was completed, the reactor was allowed to cool to room temperature and the pressure was slowly released to separate and purify the mixture. Then, the mixture was separated by column chromatography (PE:EA = 20:1) to obtain 0.61 mmol of the target product 2-phenylsuccinate dimethyl ester.

[0091] The reaction formula is as follows:

[0092]

[0093] Example 10:

[0094] The cobalt phosphine catalyst was applied to the hydrogen esterification reaction of alkynes, and the cyclic experimental steps are as follows:

[0095] (1) 1 mmol phenylacetylene, 0.02 mmol cobalt catalyst precursor CoBr2, 0.02 mmol ligand L1 and 2 mL methanol were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reaction was carried out at 120 °C for 4 h to obtain a reaction solution.

[0096] (2) After the reaction was completed, the reaction vessel was allowed to cool to room temperature, the pressure was slowly released, 1 mmol of tridecane was added as an internal standard, and the mixed solution was quantitatively analyzed by gas chromatography to obtain 0.64 mmol of the target product 2-phenylsuccinate dimethyl ester.

[0097] (3) The mixed solution in step (2) is subjected to vacuum distillation at 140°C to remove excess solvent, product, etc., and to obtain the residual catalyst;

[0098] (4) The remaining catalyst was transferred to the reaction vessel, and the substrate phenylacetylene, carbon monoxide gas and methanol were added. The reaction in steps (1)-(2) was repeated to obtain 0.59 mmol of the target product 2-phenylsuccinate dimethyl ester.

[0099] (5) Repeated operation can achieve multiple cycles, which verifies the high stability of the cobalt phosphine catalytic system.

[0100] Comparative Example 1:

[0101] The method for applying palladium-phosphine catalysts to the hydrogen esterification reaction of alkynes includes the following steps:

[0102] (1) 1 mmol phenylacetylene, 0.05 mmol catalytic precursor Pd(OAc)2, 0.05 mmol ligand L1 and 2 mL methanol were added to a high-pressure reactor, and then carbon monoxide gas was introduced to 4 MPa. The reaction was carried out at 120 °C for 20 h to obtain a reaction solution.

[0103] (2) After the reaction was completed, the reactor was allowed to cool to room temperature, the pressure was slowly released, the mixture was separated and purified, and then separated by column chromatography (PE:EA = 50:1) to obtain 0.49 mmol of the target product methyl 2-phenylacrylate.

[0104] The reaction formula is as follows:

[0105]

[0106] The results show that the conversion from alkyne substrate to dicarbonyl product cannot be achieved in the presence of palladium phosphine catalyst; however, the cobalt phosphine catalyst of the present invention can selectively prepare the dicarbonyl product - succinate, as shown in Example 9.

[0107] Comparative Example 2:

[0108] The method of applying a cobalt phosphine catalyst to the hydrogen esterification reaction of alkynes includes the following steps:

[0109] (1) Add 1 mmol phenylacetylene, 0.05 mmol catalytic precursor CoCl2, 0.05 mmol other ligands (any one of L2-L11) and 2 mL methanol to a high-pressure reactor, then purge with carbon monoxide gas to 4 MPa, and react at 120 °C for 20 h to obtain a reaction solution.

[0110] (2) After the reaction was completed, the reactor was allowed to cool to room temperature, the pressure was slowly released, and the mixture was identified. The substrate phenylacetylene did not react.

[0111] The molecular structures of other ligands L2-L11 are as follows:

[0112]

[0113] The results show that, except for L1 of the present invention, other ligands exhibit no catalytic activity when applied to cobalt-catalyzed hydrogen esterification of alkynes.

[0114] Test case

[0115] I. The cobalt phosphine catalyst (cobalt phosphine complex [Co(CO)3(L1)]) prepared in Example 1 + [Co(CO)4] - The proton NMR spectrum was performed using a Bruker DPX-400MHz NMR spectrometer (solvent: DMSO-d6, internal standard TMS). 1 H NMR detection, phosphorus spectrum ( 31 P NMR detection and X-ray single-crystal diffraction analysis were performed, and the results are shown in […]. Figure 1-3 .

[0116] Depend on Figure 1 The proton NMR shift of the cobalt phosphine complex is as follows: 1 H NMR (400MHz, DMSO-d6) δ8.91-6.60 (m, 26H), 5.23 (s, 2H), 4.72 (s, 2H);

[0117] Depend on Figure 2 It can be seen that the phosphine spectral shift of the cobalt phosphine complex is: 31P NMR (162 MHz, DMSO-d6) δ 59.82; this result further indicates that the ligand is coordinated with cobalt.

[0118] Depend on Figure 3 It is known that the crystal structure of the cobalt phosphine catalyst is [Co(CO)3(L1)]. + [Co(CO)4] - In this composition, the two p groups of the ligand are coordinated with the cobalt center and positioned axially, while the other three carbonyl groups are located in the equatorial plane, [Co(CO)4]. - As a counteracting anion.

[0119] II. The target product 2-phenylsuccinate dimethyl ester obtained in Example 6 was subjected to 1H NMR spectroscopy (NMR spectroscopy). 1 H NMR and carbon spectroscopy (H NMR) 13 (C NMR) detection, results are shown in […]. Figure 4-5 .

[0120] Depend on Figure 4 It can be seen that, 1 H NMR (400MHz, Chloroform-d) δ7.37-7.25 (m, 5H), 4.10 (dd, J=10.2, 5.2Hz, 1H), 3.68 (s, 6H), 3.22 (dd, J=17.0, 10.1Hz, 1H), 2.68 (dd, J=17.0, 5.2Hz, 1H);

[0121] Depend on Figure 5 It can be seen that, 13 C NMR (101MHz, Chloroform-d) δ 173.57, 172.12, 137.78, 129.02, 127.85, 127.81, 52.49, 52.01, 47.21, 37.75.

[0122] This demonstrates that cobalt phosphine catalysts can achieve diesterization of alkynes, enabling the direct preparation of high-value-added dicarbonyl products—succinates—from simple alkyne substrates.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The application of a cobalt phosphine catalyst in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, This catalyst is prepared by a complexation reaction of a cobalt catalytic precursor and a ligand; wherein the cobalt catalytic precursor is cobalt octacarbonyl, cobalt triacetylacetonate, cobalt diacetylacetonate, cobalt chloride, cobalt bromide, cobalt iodide, or cobalt trifluoromethanesulfonate; the molecular structure of the ligand is as follows: ; The preparation method of the cobalt phosphine catalyst includes the following steps: (1) Add the cobalt catalytic precursor and ligand to an organic solvent and react under carbon monoxide conditions for 4-36 h to obtain a reaction solution; (2) The reaction solution in step (1) was allowed to stand, the pressure was released, and then the solution was filtered and washed under reduced pressure to obtain the cobalt phosphine catalyst.

2. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (1), the molar ratio of cobalt catalytic precursor to ligand is 1:1-2; the molar volume ratio of ligand to organic solvent is 1 mmol:1-2 mL.

3. The application of the cobalt phosphine catalyst according to claim 1 or 2 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (1), the organic solvent is methanol.

4. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (1), the carbon monoxide pressure is 0.5-5 MPa.

5. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (1), the reaction is carried out at 80-140℃.

6. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (2), let it stand for 10-24 hours.

7. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In step (2), washing is performed using diethyl ether, dichloromethane, or ethyl acetate.

8. The application of the cobalt phosphine catalyst according to claim 1 in the hydrogen esterification reaction of unsaturated hydrocarbons, characterized in that, In the hydrogen esterification reaction of unsaturated hydrocarbons, a cobalt phosphine catalyst is added to carry out the catalytic reaction; or a cobalt catalytic precursor, ligand, methanol and carbon monoxide are added to the unsaturated hydrocarbons simultaneously to carry out the in-situ catalytic reaction.

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