CN112812045B - A kind of onium salt organic catalyst and its preparation method and application - Google Patents

Abstract

The invention discloses an onium salt organic catalyst, which has a structure shown in formula (I), wherein L is a urea or thiourea group; M is a charged onium salt structure; y represents a urea or thiourea group. The number can be any integer between 1 and 100000; z represents the number of onium salt groups and can be any integer between 1 and 100000. The invention also discloses a preparation method of an onium salt organic catalyst _: mixing and stirring any reaction raw material W1 and any reaction raw material W2 in a solution, stirring at room temperature for ₁ to 500 hours, removing impurities and organic solvents, An onium salt organocatalyst is obtained. The invention also discloses the application of an onium salt organic catalyst in the preparation of small organic molecules and macromolecular polymers. The onium salt organic catalyst provided by the invention has the advantages of easy weighing, high catalytic activity, controllable reaction, etc.; the preparation method provided by the invention is simple and has high yield.

Description

A kind of onium salt organic catalyst and its preparation method and application

technical field

The invention relates to the field of catalysis, in particular to the development and application of an organic catalyst that can be used in the preparation of small organic molecule fine chemicals and high molecular polymer materials.

Background technique

Compared with metal catalysts, organic catalysts have the advantages of simple synthesis, low cost, and low biological toxicity. The most widely studied organic catalysts include heterocyclic carbene (NHC), N-heterocyclic base (NHCB), hindered Lewis pair (FLP), ammonium tetrahydroxide/onium salt (PTC), polyphenols, fluoroalcohols, Silane diols with co-catalysts and ionic liquids (ILs), etc. The use of hydrogen bonding to catalyze reactions has the advantage of simplicity and ease, such as alcohols, polyphenols, carboxylic acids, silanediols, squaramides, and thioureas, which have been reported recently as the most widely studied hydrogen bonding catalysts. Among them, thiourea or urea is considered to have unique advantages in terms of toxicity, sustainability, and use under milder conditions, and has the advantages of high catalytic activity, simple preparation, and easy structure modulation.

Although urea and thiourea have good hydrogen bonding, urea or thiourea alone often does not achieve good catalytic efficiency, and generally requires quaternary ammonium salts, organic bases, etc. as co-catalysts to form an efficient catalytic system. Recently, a novel two-component catalyst consisting of a strong base and a weak acid of urea or thiourea showing high efficiency, controllability and good chemoselectivity in ring-opening polymerization of lactones was reported in [Nat.Chem.2016 , 8, 1047-1053]. Utilizing urea and thiourea as hydrogen bond donors and changing strong bases (such as sodium/potassium alkoxides) can also prepare new two-component catalysts with higher activity [J.Am.Chem.Soc.2017,139 , 1645-1652; Macromolecules 2018, 51, 2048-2053]. Similar to urea and thiourea, Kleij et al. used TEAB (Et4N ⁺ Br ^- ) and aromatic amide as a two-component catalytic system to achieve the fixation of carbon dioxide at a pressure of 10–30 bar, and obtained a high yield of cyclic carbonate[ ACS Catal. 2017, 7, 3532].

In recent years, the intramolecular combination of urea or thiourea and nucleophilic groups has more obvious advantages in the preparation of bifunctional organic catalysts in the same molecule. For example, Werner et al. developed a series of bifunctional ammonium salts and phosphorus salts, which were used to catalyze the cycloaddition reaction of carbon dioxide and epoxides [ChemCatChem.2015,7,459], and prepared various cyclic carbonate compounds. Inspired by urea or thiourea catalysts, Toda and Shirakawa introduced urea-like groups and quaternary phosphonium salts into one molecule to prepare a bifunctional catalyst that can efficiently synthesize cyclic carbonates under atmospheric pressure [ACSCatal. 2016, 6, 6906; Green Chem. 2016, 18, 4611].

In summary, the bifunctional organic catalyst has a synergistic effect of hydrogen bond activation and nucleophilic attack, which has a good effect on many organic reactions such as the activation and fixation of carbon dioxide to the synthesis of cyclic carbonates, showing more superior performance. Unfortunately, the above-mentioned catalysts still have many problems such as complex preparation, low activity, and difficult structure regulation.

Contents of the invention

The invention provides a preparation method of an onium salt organic catalyst, the preparation method is simple and the yield is high; the invention also provides the application of the onium salt organic catalyst in the preparation of fine chemicals with high added value.

The technical scheme provided by the present invention is:

A kind of onium salt organic catalyst, is characterized in that, has the structure shown in formula (I):

Wherein L is a urea or thiourea group; M is a charged onium salt structure; y represents the number of urea or thiourea groups, which can be any integer between 1 and 100000; z represents the number of onium salt groups The number can be any integer between 1 and 100000;

When y=1, K is selected from any unsubstituted or substituted C ₃ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl, C ₃ -C ₁₈ alkenyl, C ₃ -C ₁₈ alkyne One or a combination of at least two of C ₇ -C ₁₈ aryl, C ₃ -C ₁₈ heterocyclic or C ₇ -C ₁₈ heteroaryl; the substituent is selected from halogen atoms, having 1 to 10 carbon atoms branched or straight chain hydrocarbon group, 1 to 10 carbon atoms branched or straight chain alkoxy group, 3 to 10 carbon atoms branched or straight chain cycloalkyl group, 6 to 18 One or a combination of at least two aromatic groups with carbon atoms, heteroaryl groups with 5 to 18 carbon atoms;

When y is an integer ≥ 2, K is selected from unsubstituted or substituted C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl, C ₃ -C ₁₈ alkenyl, C3-C ₁₈ alkyne One or a combination of at least two of C ₆ -C ₁₈ aryl, C ₃ -C ₁₈ heterocyclic or C ₅ -C ₁₈ heteroaryl; the substituent is selected from halogen atoms, having 1 to 10 carbon atoms branched or straight chain hydrocarbon group, 1 to 10 carbon atoms branched or straight chain alkoxy group, 3 to 10 carbon atoms branched or straight chain cycloalkyl group, 6 to 18 One or a combination of at least two aryl groups with carbon atoms, heteroaryl groups with 5 to 18 carbon atoms.

Preferably, the structural formula of L is as shown in formula (II):

表示为连接键。Wherein, R ₁ , R ₃ , and R ₄ are each independently selected from H, unsubstituted, substituted, or the following groups containing one or at least two combinations of O, S, N, Si, and P atoms : C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl, C ₃ -C ₁₈ alkenyl, C3-C ₁₈ alkynyl, C ₆ -C ₁₈ aryl, C ₃ -C ₁₈ heterocyclyl or One or a combination of at least two of C ₅ -C ₁₈ heteroaryl groups; the substituents are selected from halogen atoms, branched or linear hydrocarbon groups with 1 to 10 carbon atoms, and 1 to 10 carbon atoms Of the branched or linear alkoxy groups, the branched or linear cycloalkyl groups of 3 to 10 carbon atoms, the aromatic groups of 6 to 18 carbon atoms, and the heteroaryl groups of 5 to 18 carbon atoms One or a combination of at least two; R ₂ is O or S;

Represented as a connection key.

Preferably, the M is selected from one or a combination of at least two of the following structural formulas:

Wherein, R ₅ -R ₃₈ are each independently selected from H, unsubstituted or substituted C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ cycloalkyl, C ₃ -C ₁₈ alkenyl, C3-C ₁₈ Alkynyl, C ₆ -C ₁₈ aryl, C ₃ -C ₁₈ heterocyclic or C ₅ -C ₁₈ heteroaryl or a combination of at least two; the substituent is selected from halogen atoms, having 1 Branched or straight-chain hydrocarbon groups of up to 10 carbon atoms, branched or straight-chain alkoxy groups of 1 to 10 carbon atoms, branched or straight-chain cycloalkyl groups of 3 to 10 carbon atoms, 6 to 10 carbon atoms One or a combination of at least two aromatic groups with 18 carbon atoms and heteroaryl groups with 5 to 18 carbon atoms;

X represents negative ion, selected from F ^– , Cl ^– , Br ^– , I ^– , NO ₃ ^– , CH ₃ COO ^– , CCl ₃ COO ^– , CF ₃ COO ^– , ClO ₄ ^– , BF ₄ ^– , BPh ₄ ^– , N ₃ ^– , OH ^– , p-toluate, p-toluenesulfonate, o-nitrophenolate, p-nitrophenolate, m-nitrophenolate, 2,4-dinitrophenolate, 3 ,5-Dinitrophenoloxy, 2,4,6-trinitrophenoloxy, 3,5-dichlorophenoloxy, carbonate, bicarbonate, 3,5-difluorophenoloxy, 3,5- One or a combination of at least two of di-trifluoromethylphenol oxide or pentafluorophenol oxide anion;

Any groups in each of R ₅ -R ₃₈ may form bonds with each other to form a ring.

Further preferably, the onium salt organic catalyst is:

The present invention also provides a method for preparing an onium salt organic catalyst. The preparation method is as follows _: mixing and stirring any reaction raw material W1 and any reaction raw material W2 in a solution, and stirring at room temperature for ₁ to 500 hours, Impurities and organic solvents are removed to obtain an onium salt organic catalyst; the reaction raw materials W ₁ and W ₂ are respectively:

Wherein, R ₀ is a sulfur atom or an oxygen atom; R' ₁ , R' ₂ , and R' ₃ are each independently selected from H, unsubstituted or substituted C ₁ -C ₁₈ alkyl, C ₃ -C ₁₈ ring One or at least two of alkyl, C ₃ -C ₁₈ alkenyl, C3-C ₁₈ alkynyl, C ₆ -C ₁₈ aryl, C ₃ -C ₁₈ heterocyclic or C ₅ -C ₁₈ heteroaryl The combination of species; the substituent is selected from a halogen atom, a branched or straight chain hydrocarbon group with 1 to 10 carbon atoms, a branched or straight chain alkoxy group with 1 to 10 carbon atoms, 3 to 10 One or a combination of at least two of branched or linear cycloalkyl groups of carbon atoms, aromatic groups of 6 to 18 carbon atoms, and heteroaryl groups of 5 to 18 carbon atoms;

M is a charged onium salt structure; y represents the number of urea or thiourea groups, which can be any integer between 1 and 100,000; z represents the number of onium salt groups, which can be between 1 and 100,000 any integer of .

Wherein, the organic solvent is selected from tetrahydrofuran, benzene, toluene, chloroform, hexane, ether, dichloromethane, ethyl acetate, dimethyl sulfoxide, carbon tetrachloride, 1,4-dioxane or pyridine one or more.

The reaction equation that above-mentioned preparation method involves is as follows:

The present invention also provides an application of an onium salt organic catalyst in the preparation of small organic molecules and macromolecular polymers, wherein one or at least two cyclic monomers are bulk polymerized under the contact of the organic catalyst to obtain macromolecular polymers; One or more cyclic monomers react with carbon dioxide, carbon disulfide, carbon oxysulfide or carbon monoxide in contact with an onium salt organic catalyst to obtain cyclic carbonates, cyclic lactones, cyclic thiocarbonate small molecule compounds and macromolecules polymer.

Preferably, the cyclic monomer is selected from any one or more of the following structural formulas:

The onium salt organic catalyst provided by the present invention is a kind of bifunctional organic catalyst containing urea or thiourea and onium salt simultaneously. The catalyst concentration, reaction time, reaction temperature, etc. to control the catalytic efficiency and yield) and other advantages. The preparation method provided by the invention has the advantages of simple preparation, high yield, less dosage and low cost. The onium salt organic catalyst provided by the invention can effectively synthesize fine chemicals with high added value such as cyclic carbonate, thiocyclic carbonate lactone and the like.

Description of drawings

Fig. 1 is the digital photo of the onium salt organocatalyst prepared by embodiment 1-5;

Fig. 2 is the NMR figure of the onium salt organocatalyst prepared in Example 2.

detailed description

The present invention is specifically introduced below by specific embodiment:

Alkylene oxides and their abbreviations used below

Cyclic lactones and their abbreviations used below

Example 1

(1) Add 1mmol A to a 100ml round bottom flask, add 10mL dichloromethane therein, stir until dissolved, then add 1mmol phenyl isothiocyanate, stir and react overnight at room temperature, drain to remove dichloromethane, and obtain The residue was precipitated with diethyl ether several times to remove impurities, and dried to obtain B with a yield of 83%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(2) Add 1mmol B to a 100ml round bottom flask, add 10mL acetonitrile, then add 1mmol benzyl bromide, stir and react overnight at room temperature, drain to remove acetonitrile, remove impurities by sedimentation with ethyl acetate several times, and dry to obtain onium Salt organic catalyst (catalyst 1), the yield was 87%, and the product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

Example 2

(1) Add 1mmol C to a 100ml round bottom flask, add 10mL dichloromethane therein, stir until dissolved, then add 1mmol phenyl isothiocyanate, stir and react overnight at room temperature, drain to remove dichloromethane, and obtain The residue was precipitated with diethyl ether several times to remove impurities, and dried to obtain D with a yield of 85%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(2) Add 1mmol D to a 100ml round bottom flask, add 10mL acetonitrile, then add 1.3mmol iodomethane and 1.5mmol potassium carbonate, stir and react overnight at 60°C, drain to remove acetonitrile, and remove impurities by sedimentation with ether several times , and dried to obtain an onium salt organic catalyst (catalyst 2) with a yield of 95%. The product was characterized by NMR, as shown in FIG. 2 (deuterated reagent: deuterated chloroform CDCl ₃ ).

Example 3

(1) Add 1mmol E to a 100ml round bottom flask, add 50mL methanol to it, add 1mL triethylamine and 1mmol benzaldehyde to it at low temperature, stir for 0.5h, add 2mmol NaBH ₄ in batches at low temperature, stir Reaction 1h. The resulting solution was neutralized with 4 mol/L hydrochloric acid (5 ml) and extracted with diethyl ether, the ether phase was discarded, the aqueous phase was neutralized with solid NaHCO ₃ , extracted with ethyl acetate, drained to remove ethyl acetate, and dried to obtain F, The yield was 43%, and the product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(2) Add 1mmol F to a 100ml pressure bottle, add 20mL acetonitrile, 1.5mmol potassium carbonate solid and 2.2mmol methyl iodide to it, stir and react at 50°C for 2 days, filter to remove potassium carbonate, drain to remove acetonitrile, and use Diethyl ether was precipitated several times to remove impurities and dried to obtain G with a yield of 73%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(3) Add 1mmol G to a 100ml round bottom flask, add 10mL dichloromethane to it, stir until dissolved, add 2ml trifluoroacetic acid at low temperature, and stir for 2h. Drain to remove dichloromethane, remove impurities by sedimentation with ether several times, add 10mL of dichloromethane to it, then add excess triethylamine and 2mmol phenyl isothiocyanate, stir the reaction overnight, and sedimentation with ethyl acetate several times Impurities were removed and dried to obtain an onium salt organic catalyst (catalyst 3) with a yield of 74%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

Example 4

(1) Add 1mmol diethylamine to a 100ml pressure bottle, add 10mL acetonitrile and 1.5mmol potassium carbonate solid, then add 2.5mmol I, stir and react at 50°C for 2 days, filter to remove potassium carbonate, and drain to remove Acetonitrile was precipitated with diethyl ether several times to remove impurities, and dried to obtain J with a yield of 37%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(2) Add 1mmol J to a 100ml round bottom flask, add 10mL dichloromethane into it, stir until dissolved, add 2ml trifluoroacetic acid at low temperature, and stir for 2h. Drain to remove dichloromethane, settle with ether several times to remove impurities, add 10mL of dichloromethane to it, then add excess triethylamine and 2mmol phenyl isothiocyanate, stir the reaction overnight, and remove impurities by sedimentation with ether several times , and dried to obtain an onium salt organic catalyst (catalyst 4) with a yield of 62%. The product was characterized by NMR (deuterated reagent: deuterated dimethyl sulfoxide DMSO-d6).

Example 5

(1) Add 1mmol piperidine to a 100ml pressure bottle, add 10mL acetonitrile and 1.5mmol potassium carbonate solid, then add 2.5mmol I, stir and react at 50°C for 2 days, filter to remove potassium carbonate, and drain to remove acetonitrile , was precipitated with diethyl ether several times to remove impurities, and dried to obtain K with a yield of 40%. The product was characterized by NMR (deuterated reagent: deuterated chloroform CDCl ₃ ).

(2) Add 1mmol K to a 100ml round bottom flask, add 10mL dichloromethane into it, stir until dissolved, add 2ml trifluoroacetic acid at low temperature, and stir for 2h. Drain to remove dichloromethane, settle with ether several times to remove impurities, add 10mL of dichloromethane to it, then add excess triethylamine and 2mmol phenyl isothiocyanate, stir the reaction overnight, and remove impurities by sedimentation with ether several times , and dried to obtain an onium salt organic catalyst (catalyst 5) with a yield of 58%. The product was characterized by NMR (deuterated reagent: deuterated dimethyl sulfoxide DMSO-d6).

The digital photos of Catalyst 1-Catalyst 5 prepared respectively in Examples 1-5 are shown in FIG. 1 .

Application example 1-13: Using catalyst 1-5 to catalyze the ring-opening of alkylene oxide to form cyclic carbonate

The catalyst (0.07mmol) prepared in Example 1-5 was put into an autoclave, and 35mmol of alkylene oxide was added, filled with 1.2MPa of CO ₂ , and reacted at a given temperature for 20h. Then carbon dioxide was released, and the reaction solution was taken to measure NMR to characterize the conversion rate of the monomer. The catalytic results and characterization are shown in Table 1.

The test result of the catalytic product of table 1 application example 1-13

Application Example 14-18: Using Catalyst 3 to Catalyze Homopolymerization of Cyclic Lactones

In the glove box, the catalyst 3 (0.01 mmol) prepared in Example 3 was added to a serum bottle, and a cyclic lactone (0.01 mol), 1 ml of toluene was added, and reacted at 80° C. for 6 h. The reaction solution was taken for NMR measurement to characterize the conversion rate of the monomer and the selectivity of the product, and after drying, the target polyester could be obtained. The polymers were characterized by GPC. The polymerization results and characterizations are shown in Table 2.

The test result of the polymerization product of table 2 application example 14-18

^a M _n : number average molecular weight, measured by gel permeation chromatography; ^b PDI: molecular weight distribution, measured by gel permeation chromatography.

The above-mentioned specific embodiments have described the technical solutions and beneficial effects of the present invention in detail. It should be understood that the above-mentioned are only the most preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, supplements and equivalent replacements made within the scope shall be included in the protection scope of the present invention.

Claims (2)

1. An onium salt organic catalyst, wherein the onium salt organic catalyst is:

、

、

、

or

。

2. A process for preparing the onium salt organic catalyst of claim 1, wherein said process comprises: any one of the reaction raw materials W ₁ And any one of the reaction materials W ₂ Mixing and stirring in the solution, and after stirring for 1 to 500 hours at room temperature, removing impurities and an organic solvent to obtain an onium salt organic catalyst; the reaction raw material W ₁ And W ₂ Respectively as follows:

、

；

wherein R is ₀ Is a sulfur atom or an oxygen atom; r' ₁ 、R’ ₂ 、R’ ₃ Each independently selected from H, C ₆ -C ₁₈ An aromatic group;

m is an onium salt structure with a charge; y is any integer between 1 and 100000; z is any integer between 1 and 100000;

when y =1, K is selected from unsubstituted C ₃ -C ₁₈ An alkyl group;

when y is an integer of 2 or more, K is selected from unsubstituted C ₁ -C ₁₈ An alkyl group.

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