A deep eutectic solvent, its preparation method and application

Abstract

This application provides a deep eutectic solvent, its preparation method, and its application. The method involves mixing and reacting a hydrogen bond donor and a hydrogen bond acceptor to obtain the deep eutectic solvent. This application also provides a method for preparing an acidic, halogen-free deep eutectic solvent that is acidity controllable, simple to prepare, and highly efficient. The obtained deep eutectic solvent is applied to the alkoxycarbonylation reaction of alkenes and / or alkynes. The acidic, halogen-free deep eutectic solvent acts as an acid co-catalyst in the system, achieving self-separation of the catalyst in the alkoxycarbonylation reaction of alkenes and / or alkynes, thus reducing the cost of catalyst separation. Compared to conventional homogeneous reactions, after product separation, the acidic, halogen-free deep eutectic solvent retains more activity than the homogeneous system using conventional acid co-catalysts.

Description

Technical Field

[0001] This application relates to the field of chemical process technology, specifically to a deep eutectic solvent, its preparation method, and its application. Background Technology

[0002] Palladium-catalyzed alkoxycarbonylation of alkenes and alkynes can synthesize esters with extremely high selectivity and 100% atomic efficiency, and has attracted much attention due to its compliance with the green requirements of modern industry. However, because palladium-catalyzed alkoxycarbonylation is a homogeneous reaction, the catalyst, formed in situ by ligands, acid-co-catalysts, and palladium salts, is miscible with the products and difficult to separate. Traditional separation methods such as distillation and rectification require high temperatures to separate products with larger molecular weights, and the complex structure of ligands is highly temperature-sensitive, easily leading to catalyst deactivation at high temperatures. Since ligands are often more expensive than precious metals, catalyst recovery is a pressing issue that needs to be addressed in this homogeneous reaction.

[0003] A common method for catalyst recovery is supported catalysts. However, supported catalysts suffer from high leaching rates and can only partially recover catalyst, resulting in some catalyst remaining in the product, leading to less than ideal results. Furthermore, compared to homogeneous catalysts, traditional supported catalysts experience significant loss of catalytic activity due to limited mass transfer.

[0004] Therefore, it is necessary to develop a highly stable eutectic solvent to achieve homogeneous catalysis and heterogeneous separation of the catalytic system to facilitate catalyst recovery. Summary of the Invention

[0005] This application provides a deep eutectic solvent, its preparation method, and its application, which solves the problems of difficult catalyst recovery and low activity after recovery in the current alkoxycarbonylation reaction of olefins and / or alkynes.

[0006] The method for preparing a deep eutectic solvent according to the first embodiment of this application includes: mixing and reacting a hydrogen bond donor and a hydrogen bond acceptor to obtain a deep eutectic solvent.

[0007] Optionally, in other embodiments of this application, the hydrogen bond donor includes one or more of p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, 4-nitrobenzenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, formic acid, acetic acid, oxalic acid, propionic acid, or benzoic acid.

[0008] Optionally, in other embodiments of this application, the hydrogen bond acceptor includes one or more of L-carnitine, urea, lidocaine, acetamide, benzamide, 4-aminotoluene-3-sulfonic acid, 4-pyridinecarboxylic acid, proline, 2-pyridinecarboxylic acid, N-β-hydroxyethylpiperazine, or β-alanine.

[0009] Optionally, in other embodiments of this application, the molar ratio of hydrogen bond donor to hydrogen bond acceptor is (0.2-5):1.

[0010] Optionally, in other embodiments of this application, the reaction temperature is 25°C to 200°C.

[0011] Optionally, in other embodiments of this application, the reaction time is 0.5h to 48h.

[0012] According to the eutectic solvent in the second embodiment of this application, the eutectic solvent is prepared by the above-described preparation method, and the pH value of the eutectic solvent is 0.5-7.0.

[0013] Optionally, in other embodiments of this application, the eutectic solvent is halogen-free.

[0014] The deep eutectic solvent prepared according to the preparation method described in the third embodiment of this application, or the application of the deep eutectic solvent described above in the alkoxycarbonylation reaction of olefins and / or alkynes.

[0015] Optionally, in other embodiments of this application, the alkoxycarbonylation reaction includes:

[0016] The eutectic solvent, alcohol, palladium salt and ligand are mixed in an autoclave;

[0017] Seal the autoclave and introduce carbon monoxide to purge the air from the autoclave;

[0018] Heat the autoclave, introduce carbon monoxide, add olefins and / or alkynes to react, and cycle and repeat this step.

[0019] The reaction was quenched by cooling the autoclave.

[0020] Optionally, in other embodiments of this application, the olefin includes one or more of ethylene, propylene, butene, 1,3-butadiene, 1-pentene, 2-methyl-1,3-butadiene, 1-hexene, 1,2,3,4-tetrahydrobenzene, heptene, vinylbenzene, or allylbenzene.

[0021] Optionally, in other embodiments of this application, the alkyne includes one or more of acetylene, propyne, dimethylacetylene, pentyne, hexyne, heptyne, acetylenoid, 1-phenyl-1-propyne, or 3-phenyl-1-propyne.

[0022] Optionally, in other embodiments of this application, the mass ratio of the eutectic solvent to the alcohol is (0.1 to 1.5):1.

[0023] Optionally, in other embodiments of this application, the alcohols include one or more of methanol, ethanol, ethylene glycol, 1-propanol, 2-methylpropanol, 1,2,3-propanetriol, 1-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, 2,2-dimethylpropanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, or 3-hexanol.

[0024] Optionally, in other embodiments of this application, the palladium salt includes one or more of palladium acetate, palladium chloride, palladium bromide, bis(dibenzylacetone)palladium, tris(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium, bis(triphenylphosphine)palladium(II) dichloride, palladium nitrite, palladium sulfate, ammonium tetrachloropalladate, potassium hexachloropalladate, dichlorodiammonium complex palladium, tetraammonium chloride, bis(triphenylphosphine)palladium acetate(II), or trans-bis(benzylnitrile)palladium(II).

[0025] Optionally, in other embodiments of this application, the ligand includes one or more of diphenyl-2-pyridinium phosphine, 1,2-bis(di-tert-butylphosphinemethyl)benzene, 1,1'-bis(diphenylphosphine)ferrocene, 1,3-bis(diphenylphosphinemethyl)propane, 1,2-bis(diphenylphosphinemethyl)benzene, bis[(2-diphenylphosphineyl)phenyl] ether, dimethylphenylphosphine, 1,4-bis(diphenylphosphinemethyl)butane, tripropylphosphine, 1,5-bis(diphenylphosphinemethyl)pentane, 1,2-bis(diphenylphosphinemethyl)ethane, or diphenylcyclohexylphosphine.

[0026] Optionally, in other embodiments of this application, the temperature for heating the autoclave is 60°C to 160°C.

[0027] The method for preparing the deep eutectic solvent according to the embodiments of this application has at least the following technical effects:

[0028] 1) The eutectic solvent prepared in this application has controllable acidity, serving as an acid co-catalyst in the alkoxycarbonylation reaction system of olefins and / or alkynes. This is because the reactants are alcohols and the main catalyst is Pd. 2+ The reaction involves highly polar alcohols and their products, esters, which are less polar. In the reaction, the more polar alcohols and catalysts are enriched in the polar eutectic solvent phase, while the less polar esters form a separate phase. This enables the automatic separation of the catalysts and reduces the cost of catalyst separation.

[0029] 2) The deep eutectic solvent prepared in this application is used in the alkoxycarbonylation reaction of olefins and / or alkynes. It adopts homogeneous catalysis, has no mass transfer limitation, has high catalytic activity, and the catalyst does not need to be separated at high temperature, thus avoiding catalyst deactivation.

[0030] 3) The method for preparing the deep eutectic solvent in this application is simple and has a low cost. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram showing the relationship between the degree of phase separation and time after the reaction system of Example 3 of this application has undergone 5 cycles and has been left to stand at 80°C. Detailed Implementation

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. In addition, it should be understood that the specific embodiments described herein are only for illustration and explanation of this application and are not intended to limit this application. In this application, unless otherwise stated, directional terms such as "up," "down," "left," and "right" generally refer to up, down, left, and right in the actual use or working state of the device, specifically the drawing directions in the accompanying drawings.

[0034] This application provides a deep eutectic solvent, its preparation method, and its application. These are described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments.

[0035] This application provides a method for preparing a deep eutectic solvent, comprising: mixing and reacting a hydrogen bond donor and a hydrogen bond acceptor to obtain the deep eutectic solvent. The preparation method of the deep eutectic solvent in this application is simple, requiring only a simple constant-temperature water bath and stirring. This application provides a simple, low-cost, and acidic halogen-free deep eutectic solvent with controllable acidity, which can be used in the alkoxycarbonylation reaction of olefins and alkynes. This method achieves automatic catalyst separation after the reaction of the alkoxycarbonylation system of olefins and alkynes, reducing the cost of catalyst separation and slowing down catalyst deactivation.

[0036] In some embodiments of this application, the hydrogen bond donor includes one or more of p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, 4-nitrobenzenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, formic acid, acetic acid, oxalic acid, propionic acid, or benzoic acid.

[0037] In some embodiments of this application, the hydrogen bond acceptor includes one or more of L-carnitine, urea, lidocaine, acetamide, benzamide, 4-aminotoluene-3-sulfonic acid, 4-pyridinecarboxylic acid, proline, 2-pyridinecarboxylic acid, N-β-hydroxyethylpiperazine, or β-alanine.

[0038] In some embodiments of this application, the molar ratio of hydrogen bond donor to hydrogen bond acceptor can be (0.2–5):1, (1–4):1, or (1.05–2):1. The acidity of the eutectic solvent in this application is controllable; acidity regulation can be achieved by changing the molar ratio between the hydrogen bond donor and hydrogen bond acceptor.

[0039] In some embodiments of this application, the reaction temperature can be 25°C to 200°C, 50°C to 150°C, or 80°C to 100°C.

[0040] In some embodiments of this application, the reaction time can be 0.1h to 48h, 2h to 40h, or 10h to 30h.

[0041] Accordingly, this application also provides a deep eutectic solvent, which is prepared by the above-described method. The pH value of the deep eutectic solvent can be 0.5-7.0, 1.0-6.0, or 2.0-5.0. A deep eutectic solvent refers to a two- or three-component deep eutectic mixture composed of hydrogen bond acceptors and hydrogen bond donors in a certain stoichiometric ratio, whose freezing point is significantly lower than the melting point of each pure component.

[0042] In some embodiments of this application, the eutectic solvent is halogen-free. Currently commonly used acidic eutectic solvents all contain halogens, and high concentrations of halogens can corrode equipment and poison the catalyst used in alkoxycarbonylation reactions. The eutectic solvent prepared in this application is halogen-free, reducing equipment wear and tear and preventing catalyst poisoning.

[0043] This application also provides the application of a deep eutectic solvent prepared by the above-described preparation method or the above-described deep eutectic solvent in the alkoxycarbonylation reaction of olefins and / or alkynes.

[0044] In some embodiments of this application, the alkoxycarbonylation reaction includes:

[0045] The eutectic solvent, alcohol, palladium salt and ligand are mixed in an autoclave;

[0046] Seal the autoclave and introduce carbon monoxide to purge the air from the autoclave;

[0047] Heat the autoclave, introduce carbon monoxide, add olefins and / or alkynes to react, and cycle and repeat this step.

[0048] The reaction was quenched by cooling the autoclave.

[0049] Catalysts for palladium-catalyzed alkoxycarbonylation of olefins and alkynes include palladium salts, ligands, and acid co-catalysts. The acid co-catalyst is typically a strong acid with weak coordination ability, such as p-toluenesulfonic acid or methanesulfonic acid. The main catalyst is the palladium salt. The main role of the ligand in the palladium-catalyzed alkoxycarbonylation system is to stabilize the catalyst and enhance its activity by regulating steric hindrance and charge density. The main role of the acid co-catalyst is to generate the reaction intermediate Pd-H species. Since palladium-catalyzed alkoxycarbonylation is a homogeneous reaction, the catalyst formed in situ by the ligands, acid co-catalyst, and palladium salt is miscible with the product and difficult to separate. The deep eutectic solvent used in this application as an acid co-catalyst offers advantages over traditional recovery methods. It involves fewer synthesis steps, uses low-cost chemicals as raw materials, and allows for flexible control of acidity. It can achieve simple catalyst separation while retaining the high activity characteristics of homogeneous catalysis.

[0050] In some embodiments of this application, the olefins include one or more of ethylene, propylene, butene, 1,3-butadiene, 1-pentene, 2-methyl-1,3-butadiene, 1-hexene, 1,2,3,4-tetrahydrobenzene, heptene, vinylbenzene, or allylbenzene.

[0051] In some embodiments of this application, the alkyne includes one or more of acetylene, propyne, dimethylacetylene, pentyne, hexyne, heptyne, acetylenoid, 1-phenyl-1-propyne, or 3-benzene-1-propyne.

[0052] In some embodiments of this application, the mass ratio of the eutectic solvent to the alcohol can be (0.1-1.5):1, (0.3-1.3):1, or (0.5-1):1.

[0053] In some embodiments of this application, alcohols include one or more of methanol, ethanol, ethylene glycol, 1-propanol, 2-methylpropanol, 1,2,3-propanetriol, 1-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, 2,2-dimethylpropanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, or 3-hexanol.

[0054] In some embodiments of this application, the palladium salt includes one or more of palladium acetate, palladium chloride, palladium bromide, bis(dibenzylacetone)palladium, tris(dibenzylacetone)palladium, tetra(triphenylphosphine)palladium, bis(triphenylphosphine)palladium(II) dichloride, palladium nitrite, palladium sulfate, ammonium tetrachloropalladate, potassium hexachloropalladate, dichlorodiammonium complex palladium, tetraammonium chloride, bis(triphenylphosphine)palladium acetate(II) or trans-bis(benzylnitrile)palladium(II) dichloride.

[0055] In some embodiments of this application, the ligand includes one or more of diphenyl-2-pyridinium phosphine, 1,2-bis(di-tert-butylphosphinemethyl)benzene, 1,1'-bis(diphenylphosphine)ferrocene, 1,3-bis(diphenylphosphinemethyl)propane, 1,2-bis(diphenylphosphinemethyl)benzene, bis[(2-diphenylphosphino)phenyl] ether, dimethylphenylphosphine, 1,4-bis(diphenylphosphinemethyl)butane, tripropylphosphine, 1,5-bis(diphenylphosphinemethyl)pentane, 1,2-bis(diphenylphosphinemethyl)ethane, or diphenylcyclohexylphosphine.

[0056] In some embodiments of this application, the temperature during the heating step of the autoclave can be 60°C to 160°C, 80°C to 150°C, or 100°C to 130°C.

[0057] In practice, the steps of the alkoxycarbonylation reaction include:

[0058] 1) Mix acidic halogen-free eutectic solvent and alcohol in a mass ratio of (0.1~1.5):1 in an autoclave, and add palladium salt and ligand;

[0059] 2) Seal the autoclave and introduce carbon monoxide to 0.1-6.0 MPa. Stir for 1-30 minutes and then release the gas. Repeat the operation twice to remove the air from the autoclave.

[0060] 3) After the temperature is raised to 60-160℃, olefins and alkynes are introduced with carbon monoxide in a molar ratio of (0.1-10):1. The reaction begins when the total pressure reaches 0.1-8.0 MPa. The experimental conversion rate and selectivity are recorded after the reaction time is reached, and this is recorded as cycle 1. Repeat step 3) until the reaction ends.

[0061] 4) Turn off the heating and quickly cool down to quench the reaction. After the autoclave temperature is cooled to room temperature, remove the remaining gas from the autoclave, open the autoclave body to collect the product and analyze it using gas chromatography.

[0062] The following description is based on specific embodiments.

[0063] Example 1

[0064] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0065] The method for preparing the deep eutectic solvent in this embodiment includes:

[0066] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0372 mol, 7.12 g) in a flask were mixed at a molar ratio of 1:1, and the mixture was stirred in a 90°C water bath for 4 h. A transparent liquid, acidic, halogen-free eutectic solvent No. 1 was obtained.

[0067] The application of acidic halogen-free eutectic solvent No. 1 in the synthesis of propyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-propanol includes the following steps:

[0068] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 1 (70 wt%, 5.6 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0069] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0070] 3) Heat the reactor to 100℃, and introduce a mixed gas of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a molar ratio of 1:1 to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0071] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is 72% and the selectivity of propyl propionate is >99%.

[0072] Example 2

[0073] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0074] The method for preparing the deep eutectic solvent in this embodiment includes:

[0075] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0744 mol, 14.15 g) in a molar ratio of 1:2 were mixed in a flask and stirred in a constant temperature water bath at 80 °C for 2 h to obtain a transparent liquid acidic halogen-free eutectic solvent No. 2.

[0076] The application of acidic halogen-free eutectic solvent No. 2 in the synthesis of propyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-propanol includes the following steps:

[0077] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 2 (70 wt%, 5.6 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0078] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0079] 3) Heat the reactor to 80°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0080] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is 78% and the selectivity of propyl propionate is 98%.

[0081] Example 3

[0082] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0083] The method for preparing the deep eutectic solvent in this embodiment includes:

[0084] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0391 mol, 7.43 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 80 °C for 2 h to obtain a transparent liquid No. 3 acidic halogen-free eutectic solvent at room temperature.

[0085] The application of acidic halogen-free eutectic solvent No. 3 in the synthesis of propyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-propanol includes the following steps:

[0086] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 3 (70 wt%, 5.6 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0087] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0088] 3) Heat the reactor to 80°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0089] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is >99% and the selectivity of propyl propionate is >99%.

[0090] After the reaction is complete, the clear organic phase at the top of the system is the product propyl propionate phase, and the yellow phase at the bottom is the eutectic solvent phase containing the catalyst. The organic phase at the top is poured into a flask, the product is distilled off, and 9 ml of n-propanol is added to wash the flask. This 9 ml of n-propanol is then added to the eutectic solvent phase at the bottom. The above washing and reaction steps are repeated. The catalyst can maintain a conversion rate of over 80% and a selectivity of >99% within 18 cycles. Example 3 shows that 18 cycles can be completed without a significant decrease in activity, indicating its high stability. Furthermore, the eutectic solvent and the organic product phase can be rapidly separated under reaction conditions of 80°C. Figure 1 As shown. Figure 1 The state of Example 3 after 5 catalytic cycles is shown, which separated into a clear, transparent upper organic phase and a yellow, catalyst-containing lower eutectic solvent phase. The palladium concentration in the upper product and the lower eutectic solvent phase was obtained using inductively coupled plasma optical emission spectrometry (ICP-OES), as shown in Table 1. Table 1 shows the palladium content in the upper propyl propionate phase and the lower eutectic solvent phase formed after 5 catalytic cycles of Example 3, as measured by ICP-OES. Palladium is mainly enriched in the lower eutectic solvent phase, indicating that the addition of the eutectic solvent can effectively achieve catalyst separation.

[0091] Table 1

[0092] Palladium concentration / ppm Upper propyl propionate phase 3 Lower deep eutectic solvent phase 286

[0093] Example 4

[0094] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0095] The method for preparing the deep eutectic solvent in this embodiment includes:

[0096] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0391 mol, 7.43 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 80 °C for 8 h to obtain a transparent liquid acidic halogen-free eutectic solvent No. 4 at room temperature.

[0097] The application of acidic halogen-free eutectic solvent No. 4 in the synthesis of methyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and methanol includes the following steps:

[0098] 1) Add methanol (6.328 g, 8 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 4 (70 wt%, 4.4 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0099] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0100] 3) Heat the reactor to 120°C, and introduce a 1:1 mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) to 2.0 MPa. Start timing and record the reaction pressure after 0.5 h, which is recorded as cycle 1. After cycle 1, introduce the mixture at 2.0 MPa again and record the reaction pressure after 2 h, which is recorded as cycle 2. Repeat the same steps until cycle 7.

[0101] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is >99% and the selectivity of methyl propionate is >99%.

[0102] Example 5

[0103] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0104] The method for preparing the deep eutectic solvent in this embodiment includes:

[0105] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0391 mol, 7.43 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 60 °C for 0.5 h to obtain a transparent liquid No. 5 acidic halogen-free eutectic solvent at room temperature.

[0106] The application of acidic halogen-free eutectic solvent No. 5 in the synthesis of ethyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and ethanol includes the following steps:

[0107] 1) Add ethanol (6.314 g, 8 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 5 (70 wt%, 4.4 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0108] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0109] 3) Heat the reactor to 120°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 4.

[0110] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is >99% and the selectivity of ethyl propionate is >99%.

[0111] Example 6

[0112] This embodiment provides a method for preparing a deep eutectic solvent and an alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0113] The method for preparing the deep eutectic solvent in this embodiment includes:

[0114] L-carnitine (0.0372 mol, 6 g) and p-toluenesulfonic acid monohydrate (0.0391 mol, 7.43 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 70 °C for 12 h to obtain a transparent liquid No. 6 acidic halogen-free eutectic solvent at room temperature.

[0115] The application of acidic halogen-free eutectic solvent No. 6 in the synthesis of n-butyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-butanol includes the following steps:

[0116] 1) Add n-butanol (8.098g, 10ml), palladium acetate (0.0133mmol, 3.0mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534mmol, 21.0mg) and acidic halogen-free eutectic solvent No. 6 (70wt, 5.7g) to a 50ml autoclave lined with tetrafluoroethylene;

[0117] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0118] 3) Heat the reactor to 90°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 4.

[0119] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is >99% and the selectivity of butyl propionate is >99%.

[0120] Comparative Example 1

[0121] This comparative example provides the alkoxycarbonylation reaction of olefins. The application of commercially available p-toluenesulfonic acid in the alkoxycarbonylation of ethylene with carbon monoxide and n-propanol to synthesize propyl propionate includes the following steps:

[0122] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and p-toluenesulfonic acid (0.2615 mmol, 0.05 g) to a 50 ml autoclave lined with tetrafluoroethylene;

[0123] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0124] 3) Heat the reactor to 80°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0125] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis. The conversion rate of cycle 1 is >99% and the selectivity of propyl propionate is >99%.

[0126] After cycle 5, the product containing the catalyst was distilled. 10 ml of propanol was added to the remaining catalyst after distillation, and the reaction was repeated in an autoclave. The reaction maintained a conversion rate of >80% for the first 7 cycles, but the conversion rate dropped sharply to 43% starting in the 8th cycle.

[0127] Compared with Example 3, Comparative Example 1 showed a sharp drop in conversion rate to 43% starting from the 8th cycle, while Example 3 maintained a conversion rate of over 80% and a selectivity of >99% for 18 cycles. This demonstrates that using the deep eutectic solvent of this application as an acid co-catalyst can maintain the catalyst's high catalytic activity and stability.

[0128] Comparative Example 2

[0129] This comparative example provides a method for preparing a deep eutectic solvent and the alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0130] The preparation method of the deep eutectic solvent in this comparative example includes:

[0131] Choline chloride (0.0358 mol, 5 g) and p-toluenesulfonic acid monohydrate (0.0376 mol, 7.15 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 80 °C for 2 h to obtain a transparent liquid No. 7 acidic halogen-free eutectic solvent at room temperature.

[0132] The application of eutectic solvent No. 7 in the synthesis of propyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-propanol includes the following steps:

[0133] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 7 (70 wt%, 5.6 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0134] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0135] 3) Heat the reactor to 80°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0136] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas from the autoclave. Open the autoclave body, collect the product and perform chromatographic analysis to obtain a conversion rate of 0 for cycle 1.

[0137] Compared with Example 3, the halogen-free eutectic solvent in Comparative Example 2 could complete 18 cycles, while the halogen-containing eutectic solvent in Comparative Example 2 did not react, indicating that the halogen-free eutectic solvent prepared by the method of this application improves the catalytic activity.

[0138] Comparative Example 3

[0139] This comparative example provides a method for preparing a deep eutectic solvent and the alkoxycarbonylation reaction of olefins. The specific steps are as follows:

[0140] The preparation method of the deep eutectic solvent in this comparative example includes:

[0141] L-carnitine (0.0372 mol, 6 g) and benzoic acid (0.0391 mol, 4.77 g) in a molar ratio of 1:1.05 were mixed in a flask and stirred in a constant temperature water bath at 80 °C for 2 h to obtain a transparent liquid No. 8 acidic halogen-free eutectic solvent at room temperature.

[0142] The application of eutectic solvent No. 8 in the synthesis of propyl propionate by alkoxycarbonylation of ethylene with carbon monoxide and n-propanol includes the following steps:

[0143] 1) Add n-propanol (8.04 g, 10 ml), palladium acetate (0.0133 mmol, 3.0 mg), 1,2-bis(di-tert-butylphosphine)benzene (0.0534 mmol, 21.0 mg) and acidic halogen-free eutectic solvent No. 7 (70 wt%, 5.6 g) to a 50 ml autoclave lined with tetrafluoroethylene.

[0144] 2) Seal and introduce carbon monoxide to 0.5 MPa, stir vigorously for 5 minutes and then release the gas. Repeat twice to remove the air from the autoclave.

[0145] 3) Heat the reactor to 80°C, and introduce a mixture of ethylene (0.0196 mol, 0.549 g) and carbon monoxide (0.0196 mol, 0.549 g) in a 1:1 molar ratio to 2.0 MPa. Start timing and record the reaction pressure after 2 hours, which is recorded as cycle 1. After cycle 1, introduce the mixed gas at 2.0 MPa again and record the reaction pressure after 2 hours, which is recorded as cycle 2. Repeat the same steps until cycle 5.

[0146] 4) Remove the autoclave, quickly cool it to room temperature and remove the remaining gas in the autoclave. Open the autoclave, collect the product and perform chromatographic analysis to obtain a conversion rate of 5% for cycle 1.

[0147] Comparing Comparative Example 3 with Example 3, the halogen-free eutectic solvent using p-toluenesulfonic acid as the hydrogen bond donor could complete 18 cycles, while the halogen-free eutectic solvent using benzoic acid as the hydrogen bond donor had extremely low reactivity. This indicates that the halogen-free eutectic solvent prepared by the method of this application is reasonably designed and improves the catalytic activity.

[0148] This application provides a method for preparing an acidic halogen-free deep eutectic solvent that is acidic, simple to prepare, and highly efficient. The obtained deep eutectic solvent is applied to the alkoxycarbonylation reaction of olefins and / or alkynes. The acidic halogen-free deep eutectic solvent acts as an acid co-catalyst in the system, achieving self-separation of the catalyst in the alkoxycarbonylation reaction of olefins and / or alkynes, thus reducing the cost of catalyst separation. Compared to conventional homogeneous reactions, after product separation, the acidic halogen-free deep eutectic solvent retains more activity than the acid co-catalyst in conventional homogeneous systems.

[0149] The above provides a detailed description of a deep eutectic solvent, its preparation method, and its application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. The application of a deep eutectic solvent in the alkoxycarbonylation reaction of olefins and / or alkynes, characterized in that, The method for preparing the deep eutectic solvent includes: The hydrogen bond donor and hydrogen bond acceptor are mixed and reacted to obtain the deep eutectic solvent; the hydrogen bond donor includes one or more of p-toluenesulfonic acid, p-toluenesulfonic acid monohydrate, 4-nitrobenzenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, formic acid, acetic acid, oxalic acid, propionic acid, or benzoic acid; the hydrogen bond acceptor includes one or more of L-carnitine, urea, lidocaine, acetamide, benzamide, 4-aminotoluene-3-sulfonic acid, 4-pyridinecarboxylic acid, proline, 2-pyridinecarboxylic acid, N-β-hydroxyethylpiperazine, or β-alanine; The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor is (0.2–5):1; the eutectic solvent prepared by the method is halogen-free, and the pH value of the eutectic solvent is 0.5–7.

0.

2. The application according to claim 1, characterized in that, The reaction temperature is 25℃~200℃.

3. The application according to claim 1, characterized in that, The reaction time is 0.5 h to 48 h.

4. The application according to claim 1, characterized in that, The alkoxycarbonylation reaction includes: The deep eutectic solvent, alcohol, palladium salt and ligand are mixed in an autoclave; The autoclave is sealed and carbon monoxide is introduced to purge the air from the autoclave. The autoclave is heated, carbon monoxide is introduced, and the olefin and / or alkyne are added to carry out the reaction. The reaction is quenched by cooling the autoclave.

5. The application according to claim 1, characterized in that, The olefins include one or more selected from ethylene, propylene, butene, 1,3-butadiene, 1-pentene, 2-methyl-1,3-butadiene, 1-hexene, 1,2,3,4-tetrahydrobenzene, hepten, vinylbenzene, or allylbenzene; and / or, The alkynes include one or more of acetylene, propyne, dimethylacetylene, pentyne, hexyne, heptyne, acetynebenzene, 1-phenyl-1-propyne, or 3-benzene-1-propyne.

6. The application according to claim 4, characterized in that, The mass ratio of the eutectic solvent to the alcohol is (0.1–1.5):

1.

7. The application according to claim 4, characterized in that, The alcohols include one or more of methanol, ethanol, ethylene glycol, 1-propanol, 2-methylpropanol, 1,2,3-propanetriol, 1-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 2-butanol, 1-pentanol, 3-methyl-1-butanol, 2,2-dimethylpropanol, 2-methyl-2-butanol, 1-hexanol, 2-hexanol, or 3-hexanol; and / or, The palladium salt comprises one or more of palladium acetate, palladium chloride, palladium bromide, bis(benzylacetone)palladium, tris(benzylacetone)palladium, tetra(triphenylphosphine)palladium, bis(triphenylphosphine)palladium(II) dichloride, palladium nitrite, palladium sulfate, ammonium tetrachloropalladate, potassium hexachloropalladate, dichlorodiammonium complex palladium, tetraammonium palladium chloride, bis(triphenylphosphine)palladium(II) acetate, or trans-bis(benzylnitrile)palladium(II) dichloride; and / or, The ligands include one or more of diphenyl-2-pyridinium phosphine, 1,2-bis(di-tert-butylphosphinemethyl)benzene, 1,1'-bis(diphenylphosphine)ferrocene, 1,3-bis(diphenylphosphinemethyl)propane, 1,2-bis(diphenylphosphinemethyl)benzene, bis[(2-diphenylphosphine)phenyl] ether, dimethylphenylphosphine, 1,4-bis(diphenylphosphinemethyl)butane, tripropylphosphine, 1,5-bis(diphenylphosphinemethyl)pentane, 1,2-bis(diphenylphosphinemethyl)ethane, or diphenylcyclohexylphosphine.

8. The application according to claim 4, characterized in that, In the step of heating the autoclave, the temperature is 60℃ to 160℃.

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