Application of bi-component metal complex and method for preparing beta-lactone by catalyzing carbonylation of epoxide

Abstract

The invention provides application of a bi-component metal complex to preparation of beta-lactone by catalyzing carbonylation of epoxide, the bi-component metal complex comprises a complex A and a complex B. The structure of the complex A is shown as a formula (I) or a formula (II), and the structure of the complex B is shown as a formula (III) or a formula (IV): # imgabs0. The invention also discloses a method for preparing beta-lactone by catalyzing carbonylation of epoxide by adopting the bi-component metal complex, and the method comprises the following steps: carrying out a ring amplification reaction on alkylene oxide and carbon monoxide CO under the catalytic action of the bi-component metal complex to prepare a four-membered ring beta-lactone compound. The bi-component metal complex is a catalytic system with good thermal stability and high reaction activity, and efficient preparation of beta-lactone can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of carbonylation reaction of epoxide compounds, and specifically relates to an application of a two-component metal complex and a method for preparing beta-lactone by catalyzing carbonylation of epoxide. Background Art

[0002] Using epoxide and carbon monoxide as raw materials, under the action of a catalyst, a ring-enlarged carbonylation reaction occurs to prepare β-lactones, which has received widespread attention. From the perspective of raw materials, carbon monoxide, as a C1 source, has been widely used as a raw material for many bulk chemicals such as methanol and phosgene, while epoxides can be efficiently prepared in one step by oxidation of olefins. Therefore, the wide range of raw material sources provides cost advantages for carbonylation reactions. From the perspective of products, four-membered ring β-lactones are not only synthetic precursors for complex chemicals, but also the four-membered ring structure with high ring tension makes it easier to undergo ring-opening polymerization to prepare polyhydroxy fatty acids. This type of polymer has been widely studied because of its superior mechanical properties, biocompatibility, and biodegradability. It can be seen that the carbonylation reaction of epoxides, which uses cheap raw materials to prepare high-value-added β-lactones, has extremely high research value in large-scale chemical production.

[0003] The key to achieving carbonylation reaction lies in the development of efficient catalysts. So far, a variety of catalytic systems have been developed. Among them, the [Lewisacid] + [Co(CO)4] - The research on the catalytic system is the most outstanding. The catalytic system has high catalytic efficiency and the metal ligand is easy to synthesize. It can catalyze the carbonylation reaction of epoxides of various structures with carbon monoxide (J.Am.Chem.Soc.2002,124,7,1174-1175; J.Am.Chem.Soc.2005,127,32,11426-11435). In addition, Dong Kaiwu et al. also achieved efficient carbonylation of propylene oxide and ethylene oxide using the TPPAlCl / Co2(CO)8 system (CN 114656426A); the applicant et al. developed a catalytic system of tetradentate metal complexes and metal carbonyl compounds, and achieved efficient ring expansion carbonylation reaction of alkylene oxides under mild reaction conditions (CN 115710241 A).

[0004] However, the catalytic systems developed so far all involve Co2(CO)8 or [Co(CO)4] - On the one hand, these two compounds are light sensitive and need to be kept away from light. On the other hand, during the carbonylation reaction, Co2(CO)8 and [Co(CO)4] -The high dosage increases the production cost of the carbonylation reaction, and the two will decompose at high temperatures and lose their catalytic activity, and the carbonylation reaction rate cannot be increased by increasing the reaction temperature. Therefore, the development of a catalytic system with good thermal stability and high catalytic efficiency is an urgent problem to be solved in the current epoxide carbonylation reaction. Summary of the invention

[0005] The purpose of the present invention is to provide an application of a two-component metal complex and a method for preparing β-lactone by catalyzing the carbonylation of epoxide. The two-component metal complex is a catalytic system with good thermal stability and high reaction activity, and can achieve efficient preparation of β-lactone.

[0006] The technical solution provided by the present invention is:

[0007] A two-component metal complex is used in catalyzing the carbonylation of epoxide to prepare β-lactone, comprising a complex A consisting of a metal center and its corresponding ligand, and the structure is shown in formula (I) or formula (II):

[0008]

[0009] And a complex B comprising another metal center and its corresponding ligand, the structure of which is shown in formula (III) or formula (IV):

[0010]

[0011] Wherein, M1 and M2 are metal centers, each independently selected from any same or different metal atoms of Al, Cr, Mn, Fe, Co, Ni, and In;

[0012] represents a single bond or a double bond;

[0013] X1 and X2 are each independently selected from N or S atoms; X3, X4, and X5 are each independently selected from N or P atoms;

[0014] Y is selected from Cl, Br, I, CH3COO, NO3, Co(CO)4, ClO4, BF4;

[0015] R1 is selected from C2-C6 alkylene, C3-C10 cycloalkylene, C6-C10 substituted or unsubstituted arylene;

[0016] Among them, R1 is preferably but not limited to the following structure:

[0017]

[0018] in, For a single key.

[0019] R2-R4 are one or more of H, halogen, nitro, substituted or unsubstituted C1-C10 alkyl, C1-C10 cycloalkyl, C1-C10 alkenyl, C1-C10 alkynyl, C1-C10 alkoxy, C1-C10 aromatic, C1-C10 heterocyclic, and C1-C10 heteroaryl;

[0020] R2 to R4 are preferably but not limited to the following structures:

[0021]

[0022] R5 is selected from C2-C6 alkylene;

[0023] R6~R9、R 11 ~R 13 is one or more of H, halogen, nitro, substituted or unsubstituted C1-C10 alkyl, C1-C10 cycloalkyl, C1-C10 alkenyl, C1-C10 alkynyl, C1-C10 alkoxy, C1-C10 aromatic, C1-C10 heterocyclic, and C1-C10 heteroaryl; wherein R6 and R7, R8 and R9 may form a bond to form a ring, and R 11 ~R 13 Any two can form a bond to form a ring;

[0024] R 10 It is a substituted or unsubstituted C1-C6 alkyl group with or without branch, wherein the branch and the main chain are substituted by one or more atoms of O, S, and N.

[0025] R6~R9、R 11 ~R 13 The following structures are preferred but not limited to:

[0026]

[0027] The complex A is preferably but not limited to the following structure:

[0028]

[0029] The complex B is preferably but not limited to the following structure:

[0030]

[0031] The technical concept of the present invention is that the metal center and the ligand in the structure of formula (I) and formula (II) in the complex A together form a planar conjugated structure, and the formula (III) and formula (IV) in the complex B are both composed of metal center + CO + acyl group + organic ligand. The planar structure of formula (I) and formula (II) enables the metal center in the complex A and the complex B to coordinate with the epoxy substrate during the reaction process, thereby activating the epoxy substrate; at the same time, the metal center in formula (III) and formula (IV) can attack the activated epoxy substrate to open its ring; after the ring is opened, the coordinated CO in formula (III) and formula (IV) can be ectopically inserted into the opened epoxide to realize carbonylation; in addition, the acyl group in the structure also plays an important role in stabilizing the catalyst and the intermediate in the carbonylation process.

[0032] Furthermore, the complex A is prepared by the following method:

[0033] (1) Preparation of ligand

[0034] Under nitrogen atmosphere protection, the salicylaldehyde compound represented by formula a and the diamine compound represented by formula b were dissolved in anhydrous methanol at a molar ratio of 2:1, heated under reflux for 4 hours, and the obtained reaction solution was filtered to obtain the ligand represented by formula c. C was dispersed in anhydrous methanol, sodium borohydride (the equivalent ratio of c to sodium borohydride was 1:25), stirred until the solution was clear, extracted with a dichloromethane / water system, and the organic phase was removed from the solvent to obtain the ligand represented by formula d;

[0035]

[0036] Under the protection of nitrogen atmosphere, the thiolamino compound or its salt compound shown in formula e is dissolved in anhydrous tetrahydrofuran, and then 1.25 equivalents of triethylamine are added, and after stirring, a tetrahydrofuran solution of a salicylaldehyde compound shown in formula a is added, and the mixture is heated to reflux for 2 hours. The solid is removed by filtration under the protection of nitrogen, and 1.25 equivalents of triethylamine are added to the filtrate again, and then a tetrahydrofuran solution of a 6-bromomethylphenol compound shown in formula f is added dropwise, and stirred at room temperature for 2 hours. The obtained reaction solution is post-treated to obtain a ligand shown in formula g; the ligand g is further reduced with sodium borohydride to obtain a ligand shown in formula h; the molar ratio of the thiolamino compound or its salt compound shown in formula e, the salicylaldehyde compound shown in formula a, and the 6-bromomethylphenol compound shown in formula f is 1:1.25:1;

[0037]

[0038] Under nitrogen atmosphere protection, the dithiol compound represented by formula i is dissolved in anhydrous tetrahydrofuran, and then triethylamine is added. After stirring evenly, a tetrahydrofuran solution of a 6-bromomethylphenol compound represented by formula f is added dropwise, and the mixture is stirred for reaction at room temperature for 4 hours. The obtained reaction solution is post-treated to obtain a ligand represented by formula j. The reaction formula is shown in the following formula; the molar ratio of the dithiol compound represented by formula i, triethylamine, and the 6-bromomethylphenol compound represented by formula f is 1:2.5:2;

[0039]

[0040] Pyrrole represented by formula K and aldehyde represented by formula L were added into the bottle, followed by propionic acid, and the reaction solution was refluxed for 45 minutes. The equivalent ratio of pyrrole, aldehyde and propionic acid was 1:1:6. After the reaction, the mixture was filtered and washed with methanol to obtain the ligand represented by formula M.

[0041]

[0042] (2) Preparation of complex A

[0043] Under nitrogen atmosphere, the ligands represented by formula c, d, g, h, j, and m are dissolved in tetrahydrofuran solvent respectively, and then mixed with the metal organic compound M1Y s (R alkyl ) v Stir the reaction at room temperature or with metal salt M1Y w After stirring the reaction at room temperature, oxygen is introduced for oxidation, and the resulting reaction solution is post-treated to obtain the corresponding metal complex A. Wherein, M1 and Y are as defined above, and R alky It is a C1-C5 alkyl group, and s, v and w are integers of 1-4.

[0044] The complex B is prepared by the following method:

[0045] In a nitrogen atmosphere, NaM2(CO)4 and the ligand of formula n or p are dissolved in ether. Stir under ice water for 10 minutes and purge with CO gas for a few minutes. In a CO environment, drip the ether solution of the iodine reagent of formula o into a flask, react under ice water for 1 hour and then at room temperature for 4 hours. After the reaction is completed, vacuum filter the solution. Concentrate the filtrate in vacuo and slowly add pentane under stirring. Cool the mixture in a refrigerator at -20°C overnight, filter and wash with pentane to obtain the complex of formula (III) or (IV).

[0046]

[0047] The present invention also provides a method for preparing β-lactone by carbonylation of epoxide catalyzed by a two-component metal complex, the method comprising: performing a ring expansion reaction on an alkylene oxide represented by formula (V) and carbon monoxide (CO) under the catalytic action of the two-component metal complex to prepare a four-membered ring β-lactone compound represented by formula (VI), which is represented by:

[0048]

[0049] Among them, in formula (V) and (VI), R a , R b Each is independently H, C1-C10 alkyl, C1-C10 alkoxy, or C6-C10 aromatic;

[0050] The H on the C1-C10 alkyl group or C1-C10 alkoxy group is not substituted or is substituted with one or more substituents D, and the substituents D are C6-C10 aromatic groups, C1-C5 alkyl groups, C1-C5 alkoxy groups or halogens;

[0051] The H on the C6-C10 aromatic group is not substituted or is substituted by one or more substituents E, and the substituents E are C1-C5 alkyl, C1-C5 alkoxy or halogen;

[0052] The R a , R b It can form a bond to form a ring, and together with the two carbon atoms on the epoxy group, it can form a C4-C8 cycloalkyl group or a heterocyclic group containing one or more of O, N, and S atoms in the carbon chain; the H on the cycloalkyl or heterocyclic group is not substituted or is substituted by one or more substituents C, and the substituent C is a C1-C5 alkyl group, a C1-C5 alkoxy group or a halogen.

[0053] Furthermore, the molar ratio of the two-component metal complex to the alkylene oxide is 1:100 to 200,000; preferably 1:100 to 100,000;

[0054] Furthermore, in the two-component metal complex, the molar ratio of complex A to complex B is 1:1-4.

[0055] Furthermore, the method can be carried out without solvent or in the presence of an organic solvent, wherein the organic solvent is any one of tetrahydrofuran, ethylene glycol dimethyl ether, toluene, benzene and dichloromethane.

[0056] The reaction temperature of the ring amplification reaction is 60-180° C., the reaction time is 0.1-170 hours, and the pressure of carbon monoxide is 0.1-10 MPa.

[0057] Furthermore, the method further comprises: after completion, placing in a -10°C cold bath to cool for 30 minutes, slowly releasing carbon monoxide, and performing vacuum distillation to obtain the β-lactone shown in formula (VI); after separating the product by vacuum distillation, continuing to add the epoxide shown in formula (V) and carbon monoxide into the system, and the carbonylation reaction can still be carried out.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The present invention adopts a two-component metal complex catalytic system to catalyze the carbonylation of epoxides to prepare β-lactones. The catalytic system solves the problem of traditional Co2(CO)8 or [Co(CO)4] - The components have the problems of high catalyst usage, high temperature resistance (instability at high temperature), and are not conducive to reducing the cost of industrial production. At the same time, the catalytic system requires low dosage, high catalytic efficiency, good thermal stability, the conversion rate of the substrate is up to more than 99%, and the regional selectivity of the product is up to more than 99%, which is expected to improve the industrial production efficiency of the carbonylation reaction of alkylene oxides and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 is the H NMR spectrum of β-butyrolactone;

[0061] Figure 2 This is the H NMR spectrum of β-propiolactone. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention.

[0063] Component A and its number in the catalyst system used in the examples are as follows:

[0064]

[0065] Component B and its number in the catalyst system used in the examples are as follows:

[0066] The epoxy substrates used in the examples and their numbers are as follows:

[0067]

[0068] The solvents and their abbreviations used in the examples are as follows:

[0069]

[0070] Embodiment 1-44

[0071] In a glove box, in a 50mL stainless steel autoclave, add catalytic component A (complex A), catalyst component B (complex B), epoxy substrate and solvent (if any) in turn at room temperature, then introduce a certain pressure of carbon monoxide, and quickly raise the temperature to the set temperature. After the specified reaction time, stop stirring, place in a -10°C cold bath to cool for 30 minutes, slowly release carbon monoxide, take the reaction solution and characterize it with nuclear magnetic resonance hydrogen spectrum, then distill the reaction solution to obtain pure β-lactone product. The experimental results are shown in Table 1. The obtained β-propiolactone and β-butyrolactone nuclear magnetic resonance spectra are shown in Figure 1 and Figure 2 shown.

[0072] Table 1 Epoxide carbonylation reaction conditions and results

[0073]

[0074]

[0075]

[0076] In the table:

[0077] Synthesis method of A-1:

[0078] Under nitrogen atmosphere, 2,3-butanedithiol (0.33 g, 2.0 equiv.) was dissolved in anhydrous tetrahydrofuran, followed by the addition of triethylamine (0.27 g, 2.5 equiv.), stirred evenly, and then a tetrahydrofuran solution of o-hydroxybenzyl bromide (1.0 g, 1.0 equiv.) was added dropwise, stirred at room temperature for 4 hours, and the resulting reaction solution was post-treated to obtain a ligand; under nitrogen protection, the above ligand (0.5 g, 1.0 equiv.) was dissolved in 20 mL of anhydrous tetrahydrofuran, followed by the addition of anhydrous chromium dichloride (0.22 g, 1.1 equiv.) to the reaction solution, stirred at room temperature for 24 hours, and then a sufficient amount of oxygen was introduced into the reaction system, and stirred for 3 hours. The solvent was then removed, and the crude product was washed with n-hexane to obtain a metal complex A-1.

[0079]

[0080] A-2 synthesis method:

[0081] Under nitrogen atmosphere, a thiolamino compound (0.63 g, 1.0 equiv.) was dissolved in anhydrous tetrahydrofuran, and then triethylamine (1.03 g, 1.25 equiv.) was added. After stirring, a tetrahydrofuran solution of salicylaldehyde (1.00 g, 1.0 equiv.) was added. The mixture was heated to reflux for 2 hours. The solid was removed by filtration under nitrogen protection. Triethylamine (1.03 g, 1.25 equiv.) was added to the filtrate again, and then a tetrahydrofuran solution of o-hydroxybenzyl bromide (1.53 g, 1.0 equiv.) was added dropwise. The mixture was stirred at room temperature for 2 hours. The reaction solution was post-treated to obtain a ligand. The ligand was added with Cr in the same manner as the above-mentioned preparation method of A-1.

[0082]

[0083] Synthesis method of A-3, A-4, A-7 and A-8:

[0084] Under nitrogen atmosphere, salicylaldehyde compound (2.1 equiv.) and diamine compound (1.0 equiv.) were dissolved in anhydrous methanol, heated under reflux for 4 hours, and the obtained reaction solution was filtered to obtain the ligand. The method of introducing Co and Mn into the ligand is the same as the method of introducing Cr, and A-3 and A-7 can be prepared accordingly; the method of introducing Al into the ligand is as follows: under nitrogen atmosphere, the ligand (1.0 equiv.) was dissolved in anhydrous dichloromethane, and then diethylaluminum chloride (1.1 equiv.) was added to the reaction solution, and the solvent was removed after stirring at room temperature for 24 hours, and the crude product was washed with n-hexane to obtain the metal complex A-4. The synthesis method of A-8: under nitrogen atmosphere, the ligand (1.0 equiv.) was dissolved in anhydrous tetrahydrofuran, and then manganese acetate (1.1 equiv.) was added to the reaction solution, and the solvent was removed after stirring at room temperature for 24 hours, and the crude product was washed with n-hexane to obtain the metal complex A-8.

[0085] Synthesis method of A-5, A-6 and A-9:

[0086] Pyrrole (1.0 equiv.) and aldehyde (1.0 equiv.) were added to the bottle, followed by propionic acid (6.0 equiv.), and the reaction solution was refluxed for 45 min. After the reaction, the mixture was filtered and washed with methanol to obtain the ligand. The method of introducing Cr, Al, and Co into the ligand is the same as above, and A-5, A-6, and A-9 can be prepared.

[0087]

[0088] Synthesis method of B-1 to B-8:

[0089] Taking B-3 as an example, NaCo(CO)4 (1.0 equiv.) and ligand (1.0 equiv.) are dissolved in ether in a nitrogen atmosphere. Stir under ice water for 10 minutes and purge with CO gas for a few minutes. Under a CO environment, drip methyl iodide (1.0 equiv.) in ether into the flask, react under ice water for 1 hour and then at room temperature for 4 hours. After the reaction is completed, vacuum filter the solution. Concentrate the filtrate in vacuo and slowly add pentane while stirring. Cool the mixture in a refrigerator at -20°C overnight, filter and wash with pentane to obtain B-3. The remaining metal complexes only need to use the corresponding sodium salts and ligands.

Claims

1. Application of a two-component metal complex in catalyzing the carbonylation of epoxides to prepare β-lactones. It is characterized in that The two-component metal complex comprises a complex A and a complex B, and the structure of the complex A is shown in formula (I) or formula (II): The structure of complex B is shown in formula (III) or formula (IV): Among them, M 1 、M 2 are metal centers, each independently selected from any same or different metal atoms of Al, Cr, Mn, Fe, Co, Ni, and In; represents a single or double bond; X 1 , X 2 are each independently selected from N or S atoms; X 3 , X 4 , X 5 are each independently selected from N or P atoms; Y is selected from Cl, Br, I, CH 3 COO, NO 3 , Co(CO) 4 , ClO 4 , BF 4 ; R 1 Selected from C2-C6 alkylene, C3-C10 cycloalkylene, C6-C10 substituted or unsubstituted arylene; R 2 ~R 4 is one or more of H, halogen, nitro, substituted or unsubstituted C1-C10 alkyl, C1-C10 cycloalkyl, C1-C10 alkenyl, C1-C10 alkynyl, C1-C10 alkoxy, C1-C10 aromatic, C1-C10 heterocyclic, and C1-C10 heteroaryl; R 5 An alkylene group selected from C2 to C6; R 6 ~R 9 , R 11 ~R 13 is one or more of H, halogen, nitro, substituted or unsubstituted C1-C10 alkyl, C1-C10 cycloalkyl, C1-C10 alkenyl, C1-C10 alkynyl, C1-C10 alkoxy, C1-C10 aromatic, C1-C10 heterocyclic, and C1-C10 heteroaryl; wherein R 6 With R 7 , R 8 With R 9 Can form bonds and rings, R 11 ~R 13 Any two can form a bond to form a ring; R 10 It is a substituted or unsubstituted C1-C6 alkyl group with or without branch, wherein the branch and the main chain are substituted by one or more atoms of O, S, and N.

2. The use according to claim 1, It is characterized in that The R 1 Select from the following structures: in, is a single bond; R 2 ~R 4 Select from the following structures: R 6 ~R 9 , R 11 ~R 13 Select from the following structures:

3. The use according to claim 1, It is characterized in that The structure of the complex A is selected from the following structures:

4. The use according to claim 1, It is characterized in that The structure of the complex B is selected from the following structures:

5. A method for preparing β-lactone by carbonylation of epoxide catalyzed by a two-component metal complex, It is characterized in that The method comprises: an alkylene oxide represented by formula (V) and carbon monoxide CO are subjected to a ring expansion reaction under the catalytic action of a two-component metal complex as described in any one of claims 1 to 4 to prepare a four-membered ring β-lactone compound represented by formula (VI), which is represented by: Among them, in formula (V) and (VI), R a , R b Each is independently H, C1-C10 alkyl, C1-C10 alkoxy, or C6-C10 aromatic; The H on the C1-C10 alkyl group or C1-C10 alkoxy group is not substituted or is substituted with one or more substituents D, and the substituents D are C6-C10 aromatic groups, C1-C5 alkyl groups, C1-C5 alkoxy groups or halogens; The H on the C6-C10 aromatic group is not substituted or is substituted by one or more substituents E, and the substituents E are C1-C5 alkyl, C1-C5 alkoxy or halogen; The R a , R b It can form a bond to form a ring, and together with the two carbon atoms on the epoxy group, it can form a C4-C8 cycloalkyl group or a heterocyclic group containing one or more of O, N, and S atoms in the carbon chain; the H on the cycloalkyl or heterocyclic group is not substituted or is substituted by one or more substituents C, and the substituent C is a C1-C5 alkyl group, a C1-C5 alkoxy group or a halogen.

6. The method for preparing β-lactone by carbonylation of epoxide catalyzed by a two-component metal complex as claimed in claim 5, It is characterized in that The molar ratio of the two-component metal complex to the alkylene oxide is 1:100-100000; in the two-component metal complex, the molar ratio of the complex A to the complex B is 1:1-4.

7. The method for preparing β-lactone by carbonylation of epoxide catalyzed by a two-component metal complex as claimed in claim 5, It is characterized in that The ring amplification reaction is carried out without solvent or in an organic solvent; when carried out in an organic solvent, the organic solvent is any one of tetrahydrofuran, ethylene glycol dimethyl ether, toluene, benzene and dichloromethane.

8. The method for preparing β-lactone by carbonylation of epoxide catalyzed by a two-component metal complex as claimed in claim 5, It is characterized in that The reaction temperature of the ring amplification reaction is 60-180° C., the reaction time is 0.1-170 hours, and the pressure of carbon monoxide is 0.1-10 MPa.

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