Schiff base-acyl cobalt homogeneous metal complex catalyst as well as preparation method and application thereof

Abstract

The invention discloses a Schiff base-acyl cobalt homogeneous metal complex catalyst as well as a preparation method and application thereof, and belongs to the technical field of beta-lactone preparation. The catalyst disclosed by the invention consists of two parts, namely Lewis metal halide and acyl cobalt species. Lewis acid metal halide is a metal complex formed by Schiff base and metal, acyl cobalt is a carbonylation active core formed by coordination of a bidentate phosphine ligand and a carbonyl cobalt species, and a flexible carbon chain structure in the bidentate phosphine ligand can adapt to steric hindrance of epoxide. Therefore, the carbonylation catalyst still has universality to epoxide with large steric hindrance. The valence state of the center metal Co in the acyl cobalt species is + 1 valence, and compared with Co with the valence of Co (CO) 4-to-1 valence at the active center of a traditional carbonylation catalyst, the acyl cobalt species can stably exist in the air and has good oxidation resistance. The catalyst provided by the invention has high activity and cycling stability, and lays a foundation for industrial application of carbonylation catalysts.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of beta-lactone preparation, and particularly relates to preparation of a Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl)[Co(CO)2] catalyst and application thereof in preparation of beta-lactone through ring expansion carbonylation. BACKGROUND

[0002] Beta-lactone is an important monomer for synthesis of chemical products such as succinic acid, acrylic acid and poly-beta-hydroxy fatty acid ester (abbreviated as PHA). PHA has wide application in fields such as food packaging, biomedical and industrial fermentation due to excellent biodegradability, environmental compatibility, biocompatibility and optical performance. Therefore, the demand for beta-lactone is increasing in industry, but the large-scale synthesis of beta-lactone is challenging, which leads to high price of PHA compared with other polymeric materials, and limits its large-scale application in industry.

[0003] Epoxide ring expansion carbonylation is an important way to prepare beta-lactone. Alper's group uses monometallic (Ph3P=)2NCo(CO)4 as a main catalyst and different Lewis acids BF3·Et2O, B(C6F5)3 and SnCl4 as cocatalysts to catalyze propylene oxide carbonylation reaction. The addition of cocatalysts increases the yield of beta-butyrolactone from 0% to 77%. Later, Coates' group developed a series of bimetallic catalysts [LA] + [Co(CO)4] - (LA is a Lewis acid). However, the application of such catalysts in beta-lactone production faces various challenges, such as active center [Co(CO)4] - Air sensitivity, easy oxidation and deactivation in the presence of oxygen during carbonylation, which significantly reduces the stability and activity of the catalyst. Therefore, there is an urgent need to develop a new type of catalyst with high activity and selectivity for catalyzing epoxide carbonylation at high temperature, which will promote the industrial application of homogeneous catalysts. SUMMARY

[0004] In view of the technical problems in the background art, the present application aims to provide preparation of a Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl)[Co(CO)2] catalyst and application thereof in preparation of beta-lactone through ring expansion carbonylation. The acyl cobalt species coordinated by diphosphine replaces the traditional carbonylation active center [Co(CO)4]-, which significantly improves the stability of the catalyst under high temperature reaction conditions. The catalyst has high activity and selectivity, which lays a foundation for industrial application of epoxide carbonylation reaction.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0006] In a first aspect, the present application provides a Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl)[Co(CO)2] catalyst, which is composed of two parts of Lewis acid metal halide and acyl cobalt species. The Lewis acid metal halide is a metal complex formed by a Schiff base ligand and a metal halide. The metal M coordinated with the Schiff base is one or more than two of Ga, Zn, Cr, Fe, Al, Rh, Mn, Ni, and Cu. The structure of the Lewis acid metal halide salphMX is as follows:

[0007]

[0008] The acyl cobalt species is a complex formed by a diphosphine ligand and a metal cobalt. The structure of the acyl cobalt species P-P(acyl)[Co(CO)2] is as follows:

[0009]

[0010] Based on the above technical solution, preferably, R in the acyl cobalt species is one or more than two of Me, Et, n-Pr, and i-Pr.

[0011] Based on the above technical solution, preferably, X in the Lewis acid metal halide salphMX is one or more than two of F, Cl, Br, and I; R1 is H, t-Bu, or OH; R2 is H; R3 is H, t-Bu, COOH, NMe, F, Cl, Br, CH2=CH2, or PhCH2=CH2; and R4 is H.

[0012] Based on the above technical solution, preferably, the Lewis acid metal halide salphMX is formed by coordination of a Schiff base ligand salph and a metal halide MX. The structure of the salph is as follows:

[0013]

[0014] Based on the above technical solution, preferably, R1 in the salph is H, t-Bu, or OH; R2 is H; R3 is H, t-Bu, COOH, NMe, F, Cl, Br, CH2=CH2, or PhCH2=CH2; and R4 is H.

[0015] Based on the above technical solution, preferably, the structure of the diphosphine ligand in the acyl cobalt species is as follows:

[0016]

[0017] In a second aspect, the present application provides a preparation method of the Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl)[Co(CO)2] catalyst mentioned above, comprising the following steps:

[0018] (1) chemically synthesizing Lewis acid metal halide salphMX, the steps being as follows:

[0019] salphMX1-salphMX5 and salphMX7: M=Cr, X=Cl, salph1, salph2, salph3, salph4, salph5 or salph7 and CrCl2 are dissolved in ultra-dry THF under an Ar atmosphere in a molar ratio of 1:1-1:1.5, stirred at room temperature for 2-6 h, then stirred in air for 2-6 h, the reaction system is extracted with diethyl ether, and the organic phase is washed with saturated NH4Cl and saturated NaCl respectively, dried with anhydrous Na2SO4, and then salphMX1-salphMX5 or salphMX7 is obtained after removal of the organic solvent;

[0020] salphMX6: M=Cr, X=Cl, salph6 and CrCl2 are refluxed in ethanol under an Ar atmosphere in a molar ratio of 1:1-1:1.5 for 0.5-2 h, heating is stopped, the reaction solution is exposed to air for 2-6 h, after removal of the solvent, the residue is dissolved in CH2Cl2, the organic phase is washed with deionized water and saturated brine successively, dried with anhydrous MgSO4, the solvent is evaporated, and salphCrCl6 is obtained after recrystallization of the residue;

[0021] salphMX8: M=Cr, X=Cl, salph8 and anhydrous CrCl2 are placed in a round-bottom flask in a molar ratio of 1:1-1:1.5 in a glove box, ultra-dry tetrahydrofuran (THF) is added, stirred at room temperature for 2-6 h, the round-bottom flask is placed in open air and stirred for 8-15 h, a brown precipitate is formed, filtered, washed with cold diethyl ether, and finally salenCrCl8 is obtained;

[0022] M=Mn, X=Cl, salen8 and Mn(OAc)2·4H2O are refluxed in ethanol in a molar ratio of 1:1-1:1.5 for 0.5-2 h, and then continue to reflux in an air atmosphere for 0.5-2 h, after completion of the reaction, the solvent is removed, the residue is dissolved in CH2Cl2, the organic phase is washed with deionized water and saturated brine successively, dried with anhydrous MgSO4, the solvent is evaporated, and salphMnCl8 is obtained after recrystallization of the residue;

[0023] salphMX9: M = Cr, X = Cl, in a glove box, salph9 and anhydrous CrCl2 were placed in a round bottom flask with a molar ratio of 1:1 to 1:1.5, super dry tetrahydrofuran (THF) was added, stirred at room temperature for 2-6 h, the round bottom flask was placed in open air and stirred for 8-15 h, a brown precipitate was formed, after filtration, washed with cold ether, and finally salphCrCl9 was obtained;

[0024] M = Al, X = Cl, salph9 and anhydrous AlCl3 were dissolved in anhydrous acetonitrile with a molar ratio of 1:1 to 1:1.5, refluxed at 60-80°C for 8-15 h, a yellow precipitate was formed, filtered and washed with pentane, and salphAlCl9 was obtained after vacuum drying;

[0025] (2) In a glove box, Na[Co(CO)4] and bisphosphine ligand were added to a Schlenk flask, and ether was added through a dropping funnel, and then transferred out of the glove box, stirred in an ice water bath for 5-30 min, and then a solution of CH3I, CH3CH2I, CH3(CH2)2I or CH3CH2ICH3 dissolved in ether was added dropwise into the Schlenk flask, reacted in an ice water bath for 0.5-2 h, and then reacted at room temperature for 2-6 h, the reaction solution was filtered in a glove box, the filtrate was concentrated, pentane was added and stirred uniformly, and the mixture was placed at -15 to -25°C for 8-20 h, and then filtered to obtain the acyl cobalt species P-P(acyl)[Co(CO)2;

[0026] (3) The Lewis acid metal halide salphMX and P-P(acly)[Co(CO)2] were mixed uniformly with a molar ratio of 1:1.5 to 1.5:1 to obtain the catalyst.

[0027] Based on the above technical solution, preferably, the synthesis step of the Schiff base salph in step (1) is as follows:

[0028] salph6: R1 = t-Bu, R2 = H, R3 = H, R4 = H, 3-tert-butylsalicylaldehyde and (1R, 2R)-(+)-1, 2-diphenylethylenediamine were dissolved in ethanol with a molar ratio of 4:1 to 2:1 and refluxed for 0.2-2 h, part of the solvent was removed, the solution was kept at 0-5°C for 8-14 h, and then filtered to obtain dark yellow crystals salph6;

[0029] salph8: R1 = t-Bu, R2 = H, R3 = t-Bu, R4 = H, 3,5-di-tert-butylsalicylaldehyde and (1R,2R)-(+)-1,2-cyclohexanediamine were dissolved in ethanol in a molar ratio of 4:1-2:1 and refluxed for 0.2-2 h, part of the solvent was removed, the solution was kept at 0-5 °C for 8-14 h, and then salph8 was obtained by filtration as dark yellow crystals;

[0030] salph9: R1 = t-Bu, R2 = H, R3 = H, R4 = H, 3-tert-butylsalicylaldehyde and 1,2-phenylenediamine were dissolved in anhydrous ethanol in a molar ratio of 4:1-2:1 and refluxed at 60-75 °C for 8-14 h to form a yellow precipitate, which was filtered, washed with cold ethanol and dried under vacuum to obtain the product.

[0031] Based on the above technical solution, preferably, the molar ratio of Na[Co(CO)4] and the bidentate phosphine ligand in step (2) is 1:1.

[0032] Based on the above technical solution, preferably, the synthesis steps of the bidentate phosphine ligand P-P8 in step (2) are as follows: under the protection of N2 atmosphere, magnesium pieces are added to a round-bottom flask, then iodine and part of bromobenzene are added to activate the magnesium pieces, after heating to the beginning of reflux, a THF solution of bromobenzene is added, the mixture is stirred under reflux conditions for 0.5-2 h, cooled to 0 °C, 1,2-bis(dichlorophosphino)cyclohexane is slowly added to the reaction solution using a syringe, stirred at 0 °C for 20-60 min, warmed to room temperature and stirred for 2-6 h, quenched with saturated NH4Cl aqueous solution and extracted with ethyl acetate for 2-5 times, and P-P8 is obtained after passing through a silica gel column.

[0033] Based on the above technical solution, preferably, the molar ratio of bromobenzene to 1,2-bis(dichlorophosphino)cyclohexane is 4-10:1.

[0034] In a third aspect, the present application provides the use of the Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl)[Co(CO)2] described above in the catalytic expansion carbonylation of epoxide to prepare β-lactone.

[0035] Based on the above technical solution, preferably, the substrate selected for the carbonylation is propylene oxide (PO), and the molar ratio np o / nc o of the substrate to the catalyst is 100-100000; the pressure for the carbonylation is 1-8.0 MPa; the reaction temperature is 40-200 °C; the reaction time is 1-500 h; and the reaction solvent is one of ethylene glycol dimethyl ether (DME) and THF.

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1. The acyl cobalt homogeneous metal complex SalphMCl-P-P(acly) [Co(CO)2] catalyst of the present application, the flexible diphosphine ligand of the carbonylation active center acyl cobalt species forms coordination structure with Co, the flexible carbon chain structure in the bidentate phosphine ligand can adapt to the steric hindrance of epoxide, so that the carbonylation catalyst still has universality for the epoxide with large steric hindrance.

[0038] 2. The Co in the acyl cobalt species coordinated by the diphosphine ligand is +1 valence, which is more stable than the traditional carbonylation active center [Co(CO)4] in which Co is -1 valence, and the change of the active center improves the stability and activity of the carbaltorylation catalyst. - The special structure of the acyl cobalt species of the present application significantly improves the cycle stability and activity of the catalyst, and further reduces the cost of the carbonylation catalyst in industrial application. - BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present application, the drawings involved in the embodiments will be briefly introduced below.

[0040] Figure 1 The infrared characterization graph of P-P3(acly) [Co(CO)2] solid after heating at 100℃. DETAILED DESCRIPTION

[0041] The present application will be described in detail below in combination with the embodiments, but the implementation of the present application is not limited thereto, and obviously, the embodiments described below are only some embodiments of the present application, and for those skilled in the art, other similar embodiments obtained without creative labor fall within the protection scope of the present application.

[0042] The structures of Salph1-Salph9 involved in the embodiments are as follows:

[0043]

[0044] The structures of P-P1-P-P11 involved in the embodiments are as follows:

[0045]

[0046] Embodiment 1

[0047] The synthesis of Salph1 is described in reference J. Org. Chem. 76, 2, 2011, in which R1=t-Bu, R2=H, R3=t-Bu, and R4=H.

[0048] ​Synthesis of SalphCrCl1: Salph1 (1.0 g) and CrCl2 (0.3 g, molar ratio of CrCl2 to Salph1 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the reaction system was exposed to air and stirred for another 4 h. The reaction system was extracted with diethyl ether, washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2), and dried over anhydrous Na2SO4. The organic solvent was removed by vacuum at room temperature, and then the vacuum was maintained at 60 °C for 8 h to obtain SalphCrCl1.

[0049] In a glove box, NaCo(CO)4 (1.0 g), P-P1 (purchased from Inorganic Technologies, 1.98 g, molar ratio of 1:1 to NaCo(CO)4), and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the device was transferred out of the glove box, the flask was stirred in ice water for 10 minutes, and then flushed with CO gas for several minutes. Under the CO environment, CH3I (0.9 g, 1.2 times the molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and reacted for 1 h in ice water and 4 h at room temperature. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was slowly added and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P1(acly)[Co(CO)2]. SalphCrCl1 and P-P1(acly)[Co(CO)2] were mixed to form a catalyst 1: SalphCrCl1-P-P1(acly)[Co(CO)2] at a molar ratio of 1:1.

[0050] Example 2

[0051] The synthesis of Salph2 can be found in the reference J. Phys. Chem. C 2017, 121, 16710-16720, where R1 = H, R2 = H, R3 = H, and R4 = H.

[0052] Synthesis of SalphCrCl2: Salph2 (0.5 g) and CrCl2 (0.249 g, molar ratio of CrCl2 to Salph2 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the reaction system was exposed to air and stirred for another 4 h. The reaction system was extracted with diethyl ether and washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2) respectively. The organic phase was dried with anhydrous Na2SO4, and the organic solvent was removed by vacuum at room temperature. Finally, the organic solvent was removed by vacuum at 60 °C for 8 h to obtain SalphCrCl2.

[0053] In a glove box, NaCo(CO)4 (1.0 g), P-P2 (purchased from Inorganica- Chems, 2.05 g, molar ratio of NaCo(CO)4 to P-P2 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the device was transferred out of the glove box, the flask was stirred in ice water for 10 minutes, and then flushed with CO gas for several minutes. Under the CO environment, CH3I (0.9 g, 1.2 times the molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and reacted for 1 hour under ice water and 4 hours at room temperature. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was slowly added and stirred. After the mixture was cooled to -20 °C in the refrigerator overnight, it was filtered and washed with pentane to obtain P-P2(acly)[Co(CO)2]. SalphCrCl2 and P-P2(acly)[Co(CO)2) were mixed to form a catalyst 2: SalphCrCl2-P-P2(acly)[Co(CO)2) with a molar ratio of 1:1.

[0054] Example 3

[0055] The synthesis of Salph3 can be found in the reference Appl. Organometal. Chem. 2015, 29, 425-432, wherein R1 = H, R2 = H, R3 = H, R4 = H.

[0056] Synthesis of SalphCrCl3: Salph3 (0.5 g) and CrCl2 (0.21 g, molar ratio of CrCl2 to Salph3 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the reaction system was exposed to air and stirred for another 4 h. The reaction system was extracted with diethyl ether and washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2) respectively. The organic phase was dried with anhydrous Na2SO4, and the organic solvent was removed by vacuum at room temperature. Finally, the product was obtained by vacuum at 60 °C for 8 h.

[0057] In a glove box, NaCo(CO)4 (1.0 g), P-P3 (purchased from Inorganic Technologies, 2.12 g, molar ratio of P-P3 to NaCo(CO)4 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the flask was removed from the glove box, the flask was stirred in ice water for 10 min, and then flushed with CO gas for several minutes. Under CO atmosphere, CH3I (0.9 g, 1.2 times of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and the reaction was carried out in ice water for 1 h and at room temperature for 4 h. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, and then pentane (20 mL) was slowly added and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P3(acly)[Co(CO)2]. SalphCrCl3 and P-P3(acly)[Co(CO)2] were mixed to form a catalyst 3: SalphCrCl3-P-P3(acly)[Co(CO)2] with a molar ratio of 1:1.

[0058] In air, P-P3(acly)[Co(CO)2] solid was heated at 100 °C for 10-50 min, and the heated solid was characterized by infrared spectroscopy to test its thermal stability. As shown in Figure 1 the results showed that there was no significant difference between the heated P-P3(acly)[Co(CO)2] solid and the unheated P-P3(acly)[Co(CO)2] solid, indicating that P-P3(acly)[Co(CO)2] has very good thermal stability and oxygen resistance.

[0059] Example 4

[0060] The synthesis of Salph4 can be found in the reference Tetrahedron 60 (2004), 3191-3204, wherein R1 = H, R2 = H, R3 = H, R4 = H.

[0061] Synthesis of SalphCrCl4: Salph4 (0.5 g) and CrCl2(0.264 g, molar ratio of CrCl2to Salph4 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the reaction system was exposed to air and stirred for another 4 h. The reaction mixture was extracted with diethyl ether and washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2) respectively. The organic phase was dried over anhydrous Na2SO4, and the organic solvent was removed by vacuum at room temperature. Finally, the product was obtained by vacuum at 60 °C for 8 h.

[0062] In a glove box, NaCo(CO)4(1.0 g), P-P4(bought from Inorganic Technologies, 2.20 g, molar ratio of P-P4to NaCo(CO)4is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the apparatus was transferred out of the glove box, the flask was stirred in ice water for 10 min, and then flushed with CO gas for several minutes. Under CO atmosphere, CH3I (0.9 g, 1.2 times of molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and the reaction was carried out in ice water for 1 h, and at room temperature for 4 h. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was added slowly and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P4(acly)[Co(CO)2]. SalphCrCl4and P-P4(acly)[Co(CO)2) were mixed to form a catalyst 4: SalphCrCl4-P-P4(acly)[Co(CO)2) with a molar ratio of 1:1.

[0063] Example 5

[0064] The synthesis of Salph5 is described in reference Tetrahedron 60 (2004), 3191-3204, wherein R1= H, R2= H, R3= H, R4= H.

[0065] Synthesis of SalphCrCl5: Salph5 (0.5 g) and CrCl2(0.222 g, molar ratio of CrCl2to Salph5 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the reaction system was exposed to air and stirred for another 4 h. The reaction mixture was extracted with diethyl ether and washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2) respectively. The organic phase was dried over anhydrous Na2SO4, and the organic solvent was removed by vacuum at room temperature. Finally, the product was obtained by vacuum at 60 °C for 8 h.

[0066] In a glove box, NaCo(CO)4(1.0 g), P-P5 (purchased from Inorganic Technologies, 2.27 g, molar ratio of NaCo(CO)4to P-P5 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the apparatus was transferred out of the glove box, the flask was stirred in ice water for 10 min, and then flushed with CO gas for several minutes. Under CO atmosphere, CH3I (0.9 g, 1.2 times of molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and the reaction was carried out in ice water for 1 h, and at room temperature for 4 h. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was added slowly and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P5(acly)[Co(CO)2]. SalphCrCl5 and P-P5(acly)[Co(CO)2) were combined to form a catalyst 5: SalphCrCl5-P-P5(acly)[Co(CO)2) with a molar ratio of 1:1.

[0067] Example 6

[0068] The synthesis of Salph6 was described in reference Tetrahedron 65 (2009) 305-311, in which R1 = t-Bu, R2 = H, R3 = H, R4 = H.

[0069] Synthesis of SalphCrCl6: Salph6 (1 g) and CrCl2(0.277 g, molar ratio of CrCl2to Salph6 is 1.2:1) were refluxed in ethanol for 1 h, then the heating was stopped and the reaction solution was exposed to air for 4 h. After the solvent was completely removed by distillation under reduced pressure, the residue was dissolved in CH2Cl2. The organic phase was washed successively with deionized water (3 x 25 mL), saturated brine (2 x 20 mL), dried over anhydrous MgSO4, and the solvent was evaporated. The residue was recrystallized from dichloromethane / n-hexane mixture solvent to obtain SalphCrCl6.

[0070] In a glove box, NaCo(CO)4(1.0 g), P-P6 (purchased from Inorganic Technologies, 2.34 g, molar ratio of NaCo(CO)4to P-P6 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the device was transferred out of the glove box, the flask was stirred in ice water for 10 minutes, and then flushed with CO gas for a few minutes. Under the CO environment, CH3I (0.9 g, 1.2 times the molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and reacted for 1 hour under ice water and 4 hours at room temperature. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was slowly added and stirred. After the mixture was cooled to -20°C in the refrigerator overnight, it was filtered and washed with pentane to obtain P-P6(acly)[Co(CO)2]. SalphCrCl6 and P-P6(acly)[Co(CO)2) were used to prepare catalyst 6: SalphCrCl6-P-P6(acly)[Co(CO)2) with a molar ratio of 1:1.

[0071] Example 7

[0072] The synthesis of Salph7 can be found in the reference Angew. Chem. Int. Ed. 2024, 63, e202409388, where R1 = t-Bu, R2 = H, R3 = H, R4 = H.

[0073] Synthesis of SalphCrCl7: Salph7 (0.5 g) and CrCl2(0.195 g, molar ratio of CrCl2to Salph7 is 1.2:1) were dissolved in 50 mL of super dry THF under Ar atmosphere. After stirring at room temperature for 4 h, the solution was exposed to air and stirred for another 4 h. The reaction mixture was extracted with diethyl ether and washed with saturated NH4Cl (20 mL x 2), saturated NaCl (20 mL x 2), respectively. The organic phase was dried over anhydrous Na2SO4, and the organic solvent was removed by vacuum at room temperature. Finally, the product was obtained by vacuum at 60 °C for 8 h.

[0074] In a glove box, NaCo(CO)4(1.0 g), P-P7 (purchased from Inorganic Technologies, 2.30 g, molar ratio of NaCo(CO)4to P-P7 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the apparatus was transferred out of the glove box, the flask was stirred in ice water for 10 min and then flushed with CO gas for several min. Under CO atmosphere, CH3I (0.9 g, 1.2 times of molar of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask and reacted for 1 h in ice water and 4 h at room temperature. After the reaction was completed, the flask was transferred into the glove box and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was added slowly and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to give P-P7(acly)[Co(CO)2]. SalphCrCl7 and P-P7(acly)[Co(CO)2) were used to form a catalyst 7: SalphCrCl7-P-P7(acly)[Co(CO)2) with a molar ratio of 1:1.

[0075] Example 8

[0076] The synthesis of Salph8 was described in the reference Macromol. Rapid Commun. 2003, 24, 194-196, where R1= t-Bu, R2= H, R3= H, R4= H.

[0077] In a glove box, salph8 (1 g) and anhydrous CrCl2(0.41 g, molar ratio of CrCl2to salph8 is 1.2:1) were placed in a 100 mL round bottom flask, and super dry tetrahydrofuran (THF) was added. The solution was stirred at room temperature (in the glove box) for 4 h, and the color of the solution changed rapidly from yellow-orange to brown-yellow. After 4 h, the round bottom flask was placed in open air and stirred overnight, and a shiny brown precipitate was formed. The precipitate was filtered and washed with cold diethyl ether, and finally salphCrCl8 was obtained.

[0078] Synthesis procedure of P-P8: Under N2atmosphere, magnesium turnings (2.4 g, 100 mmol) were added to a round bottom flask followed by a small piece of iodine and a small amount of bromobenzene to activate the magnesium turnings. After heating to reflux to start the reaction, a solution of bromobenzene (12.56 g, 80 mmol) in THF was added. After the dropwise addition, the mixture was stirred at reflux for 1 h. The reaction was then cooled to 0 °C and 1,2-bis(dichlorophosphino)cyclohexane (5.14 g, 100 mmol, purchased from Inorganics Technology, Inc.) was added slowly to the reaction solution using a syringe, stirred at 0 °C for 30 min, then slowly warmed to room temperature and stirred for 4 h. The reaction was quenched with saturated aqueous NH4Cl and extracted twice with ethyl acetate to give P-P8 after passing through a silica gel column.

[0079] In a glove box, NaCo(CO)4(1.0 g), P-P8 (2.33 g, 1:1 molar ratio to NaCo(CO)4) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the removal of the apparatus from the glove box, the flask was stirred in ice water for 10 min and then flushed with CO gas for a few minutes. Under CO atmosphere, a solution of CH3I (0.9 g, 1.2 molar equivalents to NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask and the reaction was allowed to proceed for 1 h in ice water and 4 h at room temperature. After the completion of the reaction, the flask was transferred back to the glove box and the solution was filtered under vacuum. The filtrate was concentrated under vacuum to about 20 mL, then pentane (20 mL) was added slowly and stirred. After the mixture was cooled to -20 °C in a freezer overnight, it was filtered and washed with pentane to give P-P8(acly)[Co(CO)2]. SalphCrCl8 was combined with P-P8(acly)[Co(CO)2) in a 1:1 molar ratio to form catalyst 8: SalphCrCl8-P-P8(acly)[Co(CO)2).

[0080] Example 9

[0081] The synthesis of Salph8 is described in reference Tetrahedron 65 (2009) 305-311, where R1 = t-Bu, R2 = H, R3 = H, R4 = H.

[0082] Salph8 (1 g) was refluxed with anhydrous Mn(OAc)2-4H2O (0.817 g, molar ratio of Mn(OAc)2-4H2O to salph8 was 1.2:1) in ethanol for 1 h. The mixture was continued to reflux for 1 h under air atmosphere. After the reaction was completed, the solvent was completely removed by distillation under reduced pressure, and the residue was dissolved in CH2Cl2. The organic phase was washed successively with deionized water (3 x 25 mL), saturated brine (2 x 20 mL), and dried over anhydrous MgSO4. After the solvent was evaporated, the residue was recrystallized from a mixture of dichloromethane / n-hexane, and salphMnCl8 was finally obtained.

[0083] In a glove box, NaCo(CO)4(1.0 g), P-P9 (purchased from Inorganic

[0084] Example 10

[0085] The synthesis of Salph9 is described in the reference ACS Appl. Mater. Interfaces 2019, 11, 18609-18616, where R1 = t-Bu, R2 = H, R3 = H, R4 = H.

[0086] In a glove box, salph9 (1 g) and anhydrous CrCl2(0.416 g, molar ratio of CrCl2 to salph9 was 1.2:1) were placed in a 100 mL round-bottom flask, and super-dry THF was added. The solution was stirred at room temperature (in the glove box) for 4 h, and the color of the solution was rapidly changed from yellow-orange to brown-yellow. After 4 h, the round-bottom flask was placed in open air and stirred overnight, and a shiny brown precipitate was formed. The precipitate was filtered and washed with cold diethyl ether, and salphCrCl9 was finally obtained.

[0087] In a glove box, NaCo(CO)4(1.0 g), P-P10 (purchased from Innoweave Technology, 2.76 g, molar ratio of P-P10 to NaCo(CO)4 is 1:1) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the apparatus was transferred out of the glove box, the flask was stirred in ice water for 10 minutes, then flushed with CO gas for several minutes. Under CO atmosphere, CH3I (0.9 g, 1.2 times mole of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask and reacted for 1 hour under ice water and 4 hours at room temperature. After the reaction was completed, the flask was transferred into the glove box, the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was added slowly and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P10(acly)[Co(CO)2]. SalphCrCl9 was mixed with P-P10(acly)[Co(CO)2] to form a catalyst 10:SalphCrCl9-P-P10(acly)[Co(CO)2] at a molar ratio of 1:1.

[0088] Example 11

[0089] The synthesis of Salph9 is described in the reference ACS Appl. Mater. Interfaces 2019, 11, 18609-18616, where R1 = t-Bu, R2 = H, R3 = H, R4 = H.

[0090] Salph9 (1 g) and anhydrous AlCl3 (0.451 g, molar ratio of AlCl3 to Salph9 is 1.2:1) were dissolved in anhydrous acetonitrile, refluxed at 70 °C for 12 h, a bright yellow precipitate was formed, filtered and washed with pentane, dried under vacuum to obtain SalphAlCl9.

[0091] In a glove box, NaCo(CO)4(1.0 g), P-P11(2.98 g, molar ratio of 1:1 to NaCo(CO)4) and diethyl ether (100 mL) were added to a Schlenk flask (250 mL) equipped with a dropping funnel. After the apparatus was transferred out of the glove box, the flask was stirred in ice water for 10 minutes, and then flushed with CO gas for several minutes. Under the CO atmosphere, a solution of CH3I (0.9 g, 1.2 times mole of NaCo(CO)4) in diethyl ether (10 mL) was added dropwise to the flask, and reacted for 1 hour under ice water and 4 hours at room temperature. After the reaction was completed, the flask was transferred into the glove box, and the solution was filtered under vacuum. The filtrate was concentrated to about 20 mL under vacuum, then pentane (20 mL) was slowly added and stirred. After the mixture was cooled to -20 °C in a refrigerator overnight, it was filtered and washed with pentane to obtain P-P11(acly)[Co(CO)2]. SalphAlCl9 was mixed with P-P11(acly)[Co(CO)2] to form a catalyst 11: SalphAlCl9-P-P11(acly)[Co(CO)2] in a molar ratio of 1:1.

[0092] Comparative Example 1

[0093] It is reported in the literature Org. Lett. 2006, 8, 3709-3712 that the homogeneous [(salph)Cr(THF)2] + [Co(CO)4] - The propylene oxide carbonylation reaction was catalyzed by the catalyst in DME solvent, the ratio of substrate and catalyst n(Sub.) / n(Cat.)=50, under the CO reaction pressure of 0.1 MPa, the reaction temperature of 22 °C and the reaction time of 6 h.

[0094] Comparative Example 2

[0095] It is reported in the literature Scientific Reports, 8(1), 13243 that the homogeneous [(TPP)Cr(THF)2] + [Co(CO)4] - The propylene oxide carbonylation reaction was catalyzed by the catalyst in THF solvent, the ratio of substrate and catalyst n(Sub.) / n(Cat.)=100, under the CO reaction pressure of 6.0 MPa, the reaction temperature of 60 °C and the reaction time of 3 h.

[0096] Application Example: Application of the catalyst prepared in Examples 1-11 in the reaction of preparing β-lactone from PO.

[0097] Autoclave reaction conditions: a certain mass of SalphMCl-P-P(acly)[Co(CO)2] catalyst was weighed and added into a 50 mL autoclave, 10 mL of ultra-dry THF was added, and PO was added, wherein n PO / n Co = 20000, 6.0 MPa of CO was filled in the autoclave in examples 1-11, and the reaction was carried out at 80°C.

[0098] The β-lactone yield, selectivity and carbonylation TOF results in the process of preparing the β-lactone according to the above operation are shown in Table 1.

[0099] Table 1. Homogeneous SalphMCl-P-P(acly)[Co(CO)2] catalytic epoxide carbonylation reaction results

[0100]

[0101] The results show that: by comparing the results of examples 1-11 and comparative examples 1-2, it can be seen that the SalphMCl-P-P(acly)[Co(CO)2] homogeneous catalyst of the present application has higher activity in catalyzing the carbonylation of PO, and the active center P-P(acly)[Co(CO)2] of the catalyst has good thermal stability and oxygen resistance at high temperature. The special structure of the active center acyl cobalt in the catalyst of the present application significantly improves the activity and stability of the catalyst, and further promotes the application of the carbonylation catalyst in industry.

[0102] The present application has been described in detail above, but the present application is not limited to the specific embodiments described herein. Other changes and modifications can be made without departing from the scope of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A homogeneous metal complex of Schiff base-acyl cobalt salphMX-P-P(acyl) [Co(CO)2] catalyst characterized in that, The catalyst is composed of two parts, Lewis acid metal halide and acyl cobalt species, the Lewis acid metal halide is a metal complex formed by Schiff base ligand and metal halide, the metal M coordinated with the Schiff base is one or more than two of Ga, Zn, Cr, Fe, Al, Rh, Mn, Ni, Cu; the structure of the Lewis acid metal halide salphMX is as follows: The acyl cobalt species is a complex formed by phosphine ligand and metal cobalt, the structure of the acyl cobalt species P-P(acyl)[Co(CO)2] is as follows:

2. The catalyst according to claim 1, characterized in that, R in the acyl cobalt species is one or more than two of Me, Et, n-Pr, i-Pr; X in the Lewis acid metal halide salphMX is one or more than two of F, Cl, Br, I; R1 is H, t-Bu or OH, R2 is H, R3 is H, t-Bu, COOH, NMe, F, Cl, Br, CH2=CH2 or PhCH2=CH2, and R4 is H.

3. The catalyst of claim 1, wherein The Lewis acid metal halide salphMX is formed by coordination of Schiff base ligand salph and metal halide MX, the structure of the salph is as follows: R1 in the salph is H, t-Bu or OH, R2 is H, R3 is H, t-Bu, COOH, NMe, F, Cl, Br, CH2=CH2 or PhCH2=CH2, and R4 is H.

4. The catalyst of claim 1, wherein The structure of the phosphine ligand in the acyl cobalt species is as follows:

5. Process for the preparation of the Schiff base-acyl cobalt homogeneous metal complex salphMX-P-P(acyl) [Co(CO)2] catalyst according to any one of claims 1 to 4, characterized in that, The method comprises the following steps: (1) chemically synthesizing the Lewis acid metal halide salphMX, the steps are as follows: salphMX1-salphMX5 and salphMX7: M=Cr, X=Cl, Salph1, Salph2, Salph3, Salph4, Salph5 or Salph7 and CrCl2 are dissolved in ultra-dry THF under Ar atmosphere at a molar ratio of 1:1-1:1.5, stirred at room temperature for 2-6 h, then exposed to air and stirred for 2-6 h, the reaction system is extracted with diethyl ether, washed with saturated NH4Cl and saturated NaCl respectively, the organic phase is dried with anhydrous Na2SO4, and after removal of the organic solvent, salphMX1-salphMX5 or salphMX7 is obtained; salphMX6: M=Cr, X=Cl, salph6 and CrCl2 are refluxed in ethanol under Ar atmosphere at a molar ratio of 1:1-1:1.5 for 0.5-2 h, heating is stopped, the reaction liquid is exposed to air for 2-6 h, after removal of the solvent, the residue is dissolved in CH2Cl2, the organic phase is washed with deionized water and saturated brine in sequence, dried with anhydrous MgSO4, evaporated to remove the solvent, and after recrystallization of the residue, salphCrCl6 is obtained; salphMX8: M = Cr, X = Cl, in the glove box, salph8 and anhydrous CrCl2 were placed in a round bottom flask with a molar ratio of 1:1 to 1:1.5, super dry tetrahydrofuran (THF) was added, stirred at room temperature for 2-6 h, the round bottom flask was placed in open air and stirred for 8-15 h, a brown precipitate was formed, filtered and washed with cold ether, and finally salenCrCl8 was obtained; M = Mn, X = Cl, salen8 and Mn(OAc)2.4H2O were refluxed in ethanol with a molar ratio of 1:1 to 1:1.5 for 0.5-2 h, then continued to reflux for 0.5-2 h under air atmosphere, after the reaction was completed, the solvent was removed, the residue was dissolved in CH2Cl2, the organic phase was washed with deionized water and saturated brine successively, dried over anhydrous MgSO4, the solvent was evaporated, and salphMnCl8 was obtained after recrystallization of the residue; salphMX9: M = Cr, X = Cl, in the glove box, salph9 and anhydrous CrCl2 were placed in a round bottom flask with a molar ratio of 1:1 to 1:1.5, super dry tetrahydrofuran (THF) was added, stirred at room temperature for 2-6 h, the round bottom flask was placed in open air and stirred for 8-15 h, a brown precipitate was formed, filtered and washed with cold ether, and finally salphCrCl9 was obtained; M = Al, X = Cl, salph9 and anhydrous AlCl3 were dissolved in anhydrous acetonitrile with a molar ratio of 1:1 to 1:1.5, refluxed at 60-80°C for 8-15 h to form a yellow precipitate, filtered and washed with pentane, and salphAlCl9 was obtained after vacuum drying; (2) In the glove box, Na[Co(CO)4] and the bidentate phosphine ligand were added to a Schlenk flask, and ether was added through a dropping funnel, then transferred out of the glove box, stirred in an ice water bath for 5-30 min, and then a solution of CH3I, CH3CH2I, CH3(CH2)2I or CH3CH2ICH3 dissolved in ether was added dropwise into the Schlenk flask, reacted in an ice water bath for 0.5-2 h, and then reacted at room temperature for 2-6 h, the reaction solution was filtered in the glove box, the filtrate was concentrated, stirred uniformly after adding pentane, and the mixture was placed at -15 to -25°C for 8-20 h, filtered to obtain the acyl cobalt species P-P(acyl)[Co(CO)2; (3) The Lewis acid metal halide salphMX was mixed with P-P(acly)[Co(CO)2] in a molar ratio of 1:1.5 to 1.5:1 to obtain the catalyst.

6. The production method according to claim 5, characterized by, The synthesis steps of the Schiff base salph in step (1) are as follows: salph6: R1 = t-Bu, R2 = H, R3 = H, R4 = H, 3-tert-butylsalicylaldehyde and (1R, 2R)-(+)-1, 2-diphenylethylenediamine were dissolved in ethanol with a molar ratio of 4:1 to 2:1, refluxed for 0.2-2 h, part of the solvent was removed, the solution was kept at 0-5°C for 8-14 h, and then filtered to obtain dark yellow crystals salph6; salph8: R1 = t-Bu, R2 = H, R3 = t-Bu, R4 = H, 3,5-di-tert-butylsalicylaldehyde and (1R,2R)-(+)-1,2-cyclohexanediamine were dissolved in ethanol in a molar ratio of 4:1 to 2:1 and refluxed for 0.2 to 2 h, part of the solvent was removed, the solution was kept at 0 to 5 °C for 8 to 14 h and then filtered to obtain dark yellow crystals of salph8; salph9: R1 = t-Bu, R2 = H, R3 = H, R4 = H, 3-tert-butylsalicylaldehyde and 1,2- phenylenediamine were dissolved in absolute ethanol in a molar ratio of 4:1 to 2:1 and refluxed at 60 to 75 °C for 8 to 14 h, a yellow precipitate was formed, which was filtered off, washed with cold ethanol and dried under vacuum to obtain the product.

7. The preparation method according to claim 5, characterized in that, The molar ratio of Na[Co(CO)4] to the bisphosphine ligand in step (2) is 1:

1.

8. The preparation method according to claim 5, characterized in that, The synthesis of the bisphosphine ligand P-P8 in step (2) is as follows: under N2 atmosphere, magnesium pieces were added to a round bottom flask, then iodine and part of bromobenzene were added to activate the magnesium pieces, after heating to reflux at the beginning of the reaction, a THF solution of bromobenzene was added, the mixture was stirred under reflux for 0.5 to 2 h, cooled to 0 °C, 1,2-bis(dichlorophosphino)cyclohexane was slowly added to the reaction solution using a syringe, stirred at 0 °C for 20 to 60 min, warmed to room temperature and stirred for 2 to 6 h, quenched with saturated aqueous NH4Cl solution and extracted with ethyl acetate for 2 to 5 times, obtained P-P8 after passing through a silica gel column; The molar ratio of bromobenzene to 1,2-bis(dichlorophosphino)cyclohexane is 4 to 10:

1.

9. Use of the catalyst according to any one of claims 1 to 4 for the catalytic cycloexpansion carbonylation of an epoxide to produce a β-lactone.

10. Use according to claim 9, characterized in that, The carbonylation is selected from propylene oxide (PO) as the substrate, the molar ratio n of the substrate and the catalyst is PO / n Co = 100-100000; the pressure of the carbonylation is 1-8.0 MPa; the reaction temperature is 40-200℃; the reaction time is 1-500 h; and the reaction solvent is one of ethylene glycol dimethyl ether (DME) and THF.

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