Method for synthesizing carbonic ester by generating active catalytic species through electrolysis

Abstract

The invention discloses a method for synthesizing carbonic ester by electrolytically generating an active catalytic species, and belongs to the field of electrolytic preparation of organic compounds, the method comprises the following steps: electrolyzing an alcohol or phenol solution of a halogen element-containing substance in a carbon monoxide atmosphere; or adding alcohol or phenol into the solution of the halogen element-containing substance for electrolysis in the atmosphere of carbon monoxide; and after the electrolytic reaction is finished, carbonic ester is collected. The synthesis method disclosed by the invention is mild in condition, simple and easy to implement, easily available in raw materials and suitable for being widely applied to conversion, transformation and derivatization of bulk industrial products such as alcohols and phenols. The carbonic ester and the derivative thereof prepared by the synthesis method have the characteristics of high synthesis efficiency, high atom economy and the like, and can be widely applied to conversion and comprehensive utilization of alcohol and phenolic compounds.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic preparation of organic compounds, and in particular to a method for synthesizing carbonate by electrolytically generating active catalytic species. Background Art

[0002] As an important bulk industrial product, carbonate is widely used in the production of electric vehicle battery electrolytes and polycarbonate chemical products. The traditional production method of carbonate is to use phosgene and alcohol to react under heating conditions to obtain carbonate and equivalent hydrochloric acid. This method requires the use of highly toxic and difficult to control phosgene as a raw material, and produces equivalent hydrochloric acid at the same time. All of the above has brought many troubles to the detection and post-processing in the production process.

[0003] In order to solve the above problems, in recent years, new carbonate synthesis methods have been reported repeatedly. For example, CN114602530A uses dimethyl carbonate as a raw material, uses copper chloride and its imidazole complex, and uses a porous material loaded with copper as a catalyst, oxidizes methanol by copper to obtain a methoxy copper complex, then inserts carbon monoxide into the copper oxygen bond, and undergoes a subsequent reduction elimination process to obtain dimethyl carbonate, while completing the circulation of the copper catalyst. In addition, CN116751124A and CN104892423A directly use a mixed gas of oxygen, carbon monoxide and methanol vapor, react under heating and pressurization conditions, and directly obtain dimethyl carbonate, thereby avoiding potential catalyst deactivation and acidic byproducts from corroding the equipment.

[0004] The current method for synthesizing carbonates requires the use of a mixed gas of carbon monoxide and oxygen, and the reaction has a certain pressure. Considering that carbon monoxide has a relatively large explosion range, the above methods all have certain safety risks in actual production applications. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention selects a suitable electrochemical medium so that substrates such as alcohols and phenols and carbon monoxide can be used to obtain carbonate products in an electrolytic cell in one step, and green hydrogen can be co-produced at the same time.

[0006] In order to achieve the above object, the present invention provides a method for synthesizing carbonate by electrolyzing active catalytic species, comprising: In a carbon monoxide atmosphere, an alcohol or phenol solution containing a halogen element is electrolyzed; or, In a carbon monoxide atmosphere, alcohol or phenol is added to a solution containing a halogen element for electrolysis; After the electrolysis reaction is completed, the carbonate is collected.

[0007] Furthermore, the concentration of the halogen-containing substance in the alcohol or phenol solution of the halogen-containing substance is 1-15 mol / L or is a saturated concentration; The concentration of the halogen-containing substance in the solution of the halogen-containing substance is 1-15 mol / L or a saturated concentration, and the alcohol or phenol is added at a concentration of 0.5-3 mol / L.

[0008] Further, the halogen-containing solute of the halogen-containing element solution includes metal halides, ammonium halides, and hydrogen halides. Exemplarily, the metal halide can be at least one of lithium chloride, sodium chloride, calcium chloride, potassium chloride, magnesium chloride, zinc chloride, cesium chloride, lithium bromide, sodium bromide, calcium bromide, potassium bromide, magnesium bromide, zinc bromide, cesium bromide, etc.; the ammonium halide can be at least one of ammonium chloride, tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, tetramethylammonium bromide, tetraethylammonium bromide, and tetrabutylammonium bromide; the hydrogen halide can be at least one of hydrogen chloride, hydrogen chloride, etc.

[0009] Furthermore, the carbon monoxide introduction rate is 5-800 mL / min.

[0010] Furthermore, the electrolysis is carried out at a constant voltage of 2-50V or a current density of 15-2000mA / cm 2 Constant current electrolysis.

[0011] Furthermore, the anode material used in the electrolysis is an inert material. Exemplarily, the inert material may be a carbon rod, carbon felt, carbon sheet, platinum, titanium plated with ruthenium, titanium plated with palladium, or titanium plated with rhodium. The cathode material does not need to be strictly limited and may be a carbon rod, carbon felt, carbon sheet, platinum, nickel, copper, iron, or stainless steel.

[0012] Furthermore, the alcohol in the alcohol solution of the halogen-containing substance includes, At least one of methanol, ethanol, ethylene glycol, ethanolamine, trifluoroethanol, acetaldehyde, n-propanol, isopropanol, hexafluoroisopropanol, cyclopropanol, allyl alcohol, propargyl alcohol, n-butanol, isobutanol, tert-butanol, cyclobutanol, alkynyl alcohol, tert-amyl alcohol, cyclopentanol, cyclohexanol, n-heptanol, cycloheptanol, n-octanol, cyclooctanol, menthol and piperonyl alcohol.

[0013] Further, the phenol in the phenol solution containing halogen element substance includes, At least one of phenol, 2-methoxyphenol and 4-methoxyphenol.

[0014] Furthermore, the solvent in the solution of the halogen-containing substance includes at least one of water, ethyl acetate, ethyl formate, acetic acid, acetonitrile, nitromethane, dichloromethane, dichloroethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and hexamethylphosphoric triamide.

[0015] The present invention also provides a carbonate ester, which is obtained by adopting the above-mentioned method for synthesizing the carbonate ester by electrolyzing and generating active catalytic species.

[0016] The concept of the present invention is that under electrolysis conditions, the halogen ions at the anode are oxidized to be converted into halogen free radicals and self-coupled into halogen elements, that is, the halogen ions are used as electrochemical media to generate halogen free radicals, which react with carbon monoxide to obtain carbonyl halides, and react with alcohols or phenols to complete the regeneration of halogen ions and obtain carbonate products.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses halogen ions as electrochemical mediators to generate halogen free radicals, which react with carbon monoxide to obtain carbonyl halides, and react with alcohols or phenols to complete the regeneration of halogen ions and obtain carbonate products. The synthesis method of the present invention has mild conditions, is simple and easy to operate, and the raw materials are easily available, and is suitable for being widely used in the conversion, transformation and derivatization of bulk industrial alcohols and phenols. The carbonates and their derivatives prepared by the synthesis method of the present invention have the characteristics of high synthesis efficiency, high atomic economy, etc., and can be widely used in the conversion and comprehensive utilization of alcohols and phenol compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic diagram of an electrolysis device used in an embodiment of the present invention is shown; Figure 2 The H-NMR spectrum of dimethyl carbonate prepared in Example 1 is shown; Figure 3 The NMR carbon spectrum of dimethyl carbonate prepared in Example 1 is shown; Figure 4 The H-NMR spectrum of ethylene carbonate prepared in Example 4 is shown; Figure 5 The NMR carbon spectrum of ethylene carbonate prepared in Example 4 is shown; Description of reference numerals; 1. Cathode cell; 11. Cathode electrode; 12. Air outlet; 2. Anode cell; 21. Anode electrode; 22. Air inlet; 3. Injection pump; 4. Cooling component. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in the present invention.

[0021] The following will be combined with the specific embodiments of the present invention and the drawings of the specification to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] In order to adapt to the conditions of the method for synthesizing carbonate esters by electrolysis to generate active catalytic species of the present invention, the following was adopted: Figure 1 The device shown adopts a separated electrolytic cell, which includes a cathode pool 1 and an anode pool 2 separated by a diaphragm, as well as an injection pump 3, an external power supply, a carbon monoxide component, a cooling component 4, a hydrogen collection component, and an exhaust gas treatment component; the external power supply, the carbon monoxide component, the hydrogen collection component, and the exhaust gas treatment component are not shown in the figure; a cathode electrode 11 and an anode electrode 21 are respectively arranged in the cathode pool 1 and the anode pool 2; the cathode electrode 11 and the anode electrode 21 are connected to the external power supply; the carbon monoxide component is connected to the air inlet 22 at the top of the anode pool 2; the anode pool 2 is connected to the cooling component 4 and the exhaust gas treatment component in turn; the hydrogen collection component is connected to the air outlet 12 at the top of the cathode pool 1; and the injection pump 3 is used to inject reactants into the anode pool 2. The preparation conditions of the following embodiments are all provided by this device.

[0023] Example 1 Add 15 mL of 2 mol / L methanol solution of hydrogen chloride to the cathode and anode cells respectively. Use the graphite sheet as cathode and the platinum electrode as anode at 100 mA / cm 2 The electrolysis was carried out at a constant current density of 12 hours. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the fraction with a boiling range of 89-90°C was collected by distillation, totaling 1.11 g. The product was mainly dimethyl carbonate determined by gas chromatography, and the purity of dimethyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 55%. 1 H NMR (400 MHz, CDCl3) δ3.78 (s, 6H), 13 C NMR (125 MHz, CDCl3) δ54.8, 156.3. Figure 2 and Figure 3 .

[0024] Example 2 15 mL of saturated lithium chloride methanol solution was added to the cathode cell and the anode cell respectively. The graphite sheet was used as the cathode and the platinum electrode was used as the anode. 2 The electrolysis was carried out at a constant current density of 12 hours. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the fraction with a boiling range of 89-90°C was collected by distillation, totaling 1.35 g. The product was mainly dimethyl carbonate determined by gas chromatography, and the purity of dimethyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 67%.

[0025] Example 3 Add 15 mL of 2.5 mol / L methanol solution of hydrogen bromide to the cathode and anode cells respectively. Use the graphite sheet as cathode and the platinum electrode as anode at 100 mA / cm 2 The electrolysis was carried out at a constant current density of 12 hours. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the fraction with a boiling range of 89-90°C was collected by distillation, totaling 1.27 g. The product was mainly dimethyl carbonate determined by gas chromatography, and the purity of dimethyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 63%.

[0026] Example 4 15 mL of 2 mol / L aqueous solution of hydrogen chloride was added to the cathode cell and the anode cell respectively. Then ethylene glycol was added to the anode cell using a syringe pump until its concentration in the anode cell was 2 mol / L. The graphite sheet was used as the cathode and the titanium ruthenium-plated electrode was used as the anode. The flow rate was 100 mA / cm 2 The electrolysis was carried out at a constant current density of 12 h. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.25 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum drying, and the residue was 1.06 g in total. The product was mainly ethylene carbonate determined by gas chromatography, and the purity of ethylene carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 54%. 1 H NMR (400 MHz, CDCl3) δ4.51 (s, 4H), 13 CNMR (125 MHz, CDCl3) δ64.5, 155.4. For NMR characterization, see Figure 4 and Figure 5 .

[0027] Example 5 15 mL of 2 mol / L aqueous solution of hydrogen bromide was added to the cathode cell and the anode cell respectively. Then, ethylene glycol was added to the anode cell using a syringe pump until its concentration in the anode cell was 1 mol / L. A graphite sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The flow rate was 100 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 1000 nm for 12 h, during which carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.25 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum drying, and a total of 1.42 g of residue was obtained. The product was determined by gas chromatography to be mainly ethylene carbonate, and the purity of ethylene carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 72%.

[0028] Example 6 15 mL of 2 mol / L aqueous solution of hydrogen chloride was added to the cathode cell and the anode cell respectively. Then n-propanol was added to the anode cell using a syringe pump until its concentration in the anode cell was 5 mol / L. The graphite sheet was used as the cathode and the titanium ruthenium-plated electrode was used as the anode. The flow rate was 100 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 1000 nm for 12 h, during which carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. The reaction solution was alkalized with a 0.25 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, excess solvent was removed under vacuum, leaving a total of 1.57 g of residue. The product was mainly dipropyl carbonate determined by gas chromatography, and the purity of dipropyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 48%.

[0029] Example 7 15 mL of 2 mol / L aqueous solution of hydrogen bromide was added to the cathode cell and the anode cell respectively. Then, n-propanol was added to the anode cell using a syringe pump until its concentration in the anode cell was 2.5 mol / L. A graphite sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The flow rate was 100 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 1000 nm for 12 h, during which carbon monoxide was continuously introduced into the reaction system at a flow rate of 10 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.25 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum, and a total of 1.80 g of residue was obtained. The product was mainly dipropyl carbonate determined by gas chromatography, and the purity of dipropyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 55%.

[0030] Example 8 15 mL of saturated sodium chloride solution in N,N-dimethylformamide was added to the cathode and anode cells respectively. Phenol was then added to the anode cell using a syringe pump until its concentration in the anode cell was 2 mol / L. A platinum sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The reaction was carried out at 200 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 3 h for 3 h. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 5 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.5 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum, and a total of 0.79 g of residue was obtained. The product was mainly diphenyl carbonate determined by gas chromatography, and the purity of diphenyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 33%.

[0031] Example 9 15 mL of 2 mol / L hydrogen chloride in N,N-dimethylformamide solution was added to the cathode and anode cells respectively. Phenol was then added to the anode cell using a syringe pump until its concentration in the anode cell was 1 mol / L. A platinum sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The reaction was carried out at 200 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 3 h for 3 h. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 5 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.5 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum, and a total of 1.01 g of residue was obtained. The product was mainly diphenyl carbonate determined by gas chromatography, and the purity of diphenyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 42%.

[0032] Example 10 15 mL of 2 mol / L hydrogen bromide in N,N-dimethylformamide solution was added to the cathode and anode cells respectively. Phenol was then added to the anode cell using a syringe pump until its concentration in the anode cell was 2 mol / L. A platinum sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The reaction was carried out at 200 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 3 h for 3 h. During the process, carbon monoxide was continuously introduced into the reaction system at a flow rate of 5 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.5 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum, and a total of 1.08 g of residue was obtained. The product was mainly diphenyl carbonate determined by gas chromatography, and the purity of diphenyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 45%.

[0033] Embodiment 11 15 mL of 2 mol / L hydrogen chloride in dimethyl sulfoxide solution was added to the cathode and anode cells respectively. Phenol was then added to the anode cell using a syringe pump until its concentration in the anode cell was 2 mol / L. A platinum sheet was used as the cathode and a titanium ruthenium-plated electrode was used as the anode. The reaction was carried out at 200 mA / cm 2 The reaction mixture was electrolyzed at a constant current density of 3 h for 3 h, during which carbon monoxide was continuously introduced into the reaction system at a flow rate of 5 mL / min using a carbon monoxide component. After the electrolysis reaction was completed, the reaction solution was alkalized with a 0.5 mol / L sodium hydroxide aqueous solution, extracted with ether, and the organic phase was collected. After drying over anhydrous magnesium sulfate, the excess solvent was removed under vacuum, and a total of 1.46 g of residue was obtained. The product was mainly diphenyl carbonate determined by gas chromatography, and the purity of diphenyl carbonate was greater than 98%; the Faraday efficiency of the electrolysis process was 61%.

[0034] In summary, the present invention uses halogen ions as electrochemical mediators to generate halogen free radicals, which react with carbon monoxide to obtain carbonyl halides, and react with alcohols or phenols to complete the regeneration of halogen ions and obtain carbonate products. The synthesis method of the present invention has mild conditions, is simple and easy to operate, and the raw materials are easily available, and is suitable for being widely used in the conversion, transformation and derivatization of bulk industrial alcohols and phenols. The carbonates and their derivatives prepared by the synthesis method of the present invention have the characteristics of high synthesis efficiency, high atomic economy, etc., and can be widely used in the conversion and comprehensive utilization of alcohols and phenolic compounds.

[0035] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for synthesizing carbonates by electrolyzing active catalytic species, characterized in that: include, In a carbon monoxide atmosphere, an alcohol or phenol solution containing a halogen element is electrolyzed; or, In a carbon monoxide atmosphere, alcohol or phenol is added to a solution containing a halogen element for electrolysis; After the electrolysis reaction is completed, the carbonate is collected.

2. The method for synthesizing carbonate by electrolytic generation of active catalytic species according to claim 1, characterized in that: The concentration of the halogen-containing substance in the alcohol or phenol solution of the halogen-containing substance is 1-15 mol / L or is a saturated concentration; The concentration of the halogen-containing substance in the solution of the halogen-containing substance is 1-15 mol / L or a saturated concentration, and the alcohol or phenol is added at a concentration of 0.5-3 mol / L.

3. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The carbon monoxide introduction rate is 5-800 mL / min.

4. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The electrolysis adopts constant voltage electrolysis with a voltage of 2-50V or a current density of 15-2000mA / cm 2 Constant current electrolysis.

5. The method for synthesizing carbonate by electrolytic generation of active catalytic species according to claim 1, characterized in that: The anode material used in the electrolysis is an inert material.

6. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The halogen-containing solute of the halogen-containing element solution includes metal halides, ammonium halides and hydrogen halides.

7. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The alcohol in the alcohol solution of the halogen-containing substance includes: At least one of methanol, ethanol, ethylene glycol, ethanolamine, trifluoroethanol, acetaldehyde, n-propanol, isopropanol, hexafluoroisopropanol, cyclopropanol, allyl alcohol, propargyl alcohol, n-butanol, isobutanol, tert-butanol, cyclobutanol, alkynyl alcohol, tert-amyl alcohol, cyclopentanol, cyclohexanol, n-heptanol, cycloheptanol, n-octanol, cyclooctanol, menthol and piperonyl alcohol.

8. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The phenol in the phenol solution containing halogen element substances includes: At least one of phenol, 2-methoxyphenol and 4-methoxyphenol.

9. The method for synthesizing carbonate by electrolytically generating active catalytic species according to claim 1, characterized in that: The solvent in the solution of the halogen-containing substance includes at least one of water, ethyl acetate, ethyl formate, acetic acid, acetonitrile, nitromethane, dichloromethane, dichloroethane, chloroform, tetrahydrofuran, N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, and hexamethylphosphoric triamide.

10. A carbonate ester, characterized in that The method for synthesizing carbonate by electrolyzing active catalytic species as described in any one of claims 1 to 9 is used to obtain the carbonate.

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