Oxidation method for toluene and / or derivative thereof

Abstract

The present application relates to an oxidation method for toluene and / or a derivative thereof. The oxidation method for toluene and / or a derivative thereof comprises the following steps: using an electrolytic process to electrolyze one or more components of the toluene and the derivative thereof to oxidize the toluene and / or the derivative thereof, wherein an anolyte used in the electrolytic process contains divalent cobalt ions.

Description

Method for oxidizing toluene and / or its derivatives

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202311024622.3, filed on August 15, 2023, entitled “Process for the oxidation of toluene and its derivatives,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of organic chemical synthesis, and in particular to a method for oxidizing toluene and / or its derivatives. Background Art

[0004] The oxidation of toluene and / or its derivatives is an important method for producing aromatic aldehydes and aromatic acids. For example, benzoic acid and its sodium salt, the oxidation products of toluene, are widely used as preservatives and feed additives in food and beverages, and are also widely used in plasticizers, pharmaceuticals, dyes, and other fields. Another product, benzaldehyde, is used as a specialty fragrance and, due to its readily reactive aldehyde group, is a valuable intermediate for various fine chemicals. Furthermore, terephthalic acid, the oxidation product of p-xylene, is a major organic raw material used extensively in the production of polyester materials relevant to the national economy.

[0005] Currently, the primary method used industrially to oxidize toluene and its derivatives is liquid-phase oxidation, with the SINA process being the most widely used. Due to the insufficient oxidizing capacity of oxygen, the SINA process requires temperatures and pressures of 165°C and 1 MPa, respectively, for oxidation to occur. Furthermore, the reaction takes place in a stirred tank, creating a large gas phase space and posing an explosion risk under high temperature and pressure. Furthermore, since the reaction process does not utilize a solvent, the formation of cobalt salts is a serious problem. Consequently, liquid-phase oxidation methods for toluene and its derivatives, such as the SINA process, suffer from harsh reaction conditions, high energy consumption, and poor safety.

[0006] In response to this, some researchers have designed new co-catalysts and reactors to improve the efficiency of the oxidation reaction, but the problems of harsh conditions and high safety risks of the liquid-phase oxidation method have not been avoided.

[0007] Summary of the Invention

[0008] Based on this, it is necessary to provide a method for oxidizing toluene and / or its derivatives, which has the characteristics of low energy consumption, mild reaction conditions, good safety, and can improve the yield of toluene and / or its derivatives oxidation products.

[0009] The present application provides a method for oxidizing toluene and / or its derivatives, comprising the following steps:

[0010] One or more components of toluene and its derivatives are electrolyzed by an electrolysis method to oxidize the toluene and / or its derivatives; the anolyte used in the electrolysis method contains divalent cobalt ions.

[0011] In some embodiments, in the anolyte, the concentration of the divalent cobalt ions is 0.03 mol / L to 0.2 mol / L.

[0012] In some embodiments, the step of electrolyzing one or more components of toluene and its derivatives by electrolysis comprises:

[0013] preparing an anolyte and a catholyte, wherein the anolyte comprises divalent cobalt ions;

[0014] The anolyte and the cathode liquid are assembled to form an electrolytic cell, and one or more components of toluene and its derivatives are added to the anolyte to perform electrolysis to oxidize the toluene and / or its derivatives.

[0015] In some embodiments, the anolyte further comprises a first supporting electrolyte, and the catholyte further comprises a second supporting electrolyte.

[0016] In some embodiments, the first supporting electrolyte and the second supporting electrolyte are independently selected from one or more of tetrabutylammonium acetate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate, tetraethylammonium tetrafluoroborate, tetraethylammonium perchlorate and lithium tetrafluoroborate.

[0017] In some embodiments, in the anolyte, the concentration of the first supporting electrolyte is 0.05 mol / L to 0.2 mol / L.

[0018] In some embodiments, in the cathode solution, the concentration of the second supporting electrolyte is 0.05 mol / L to 0.2 mol / L.

[0019] In some embodiments, in the anolyte, the concentration of toluene and / or its derivatives is 0.05 mol / L to 0.2 mol / L.

[0020] In some embodiments, the electrolysis temperature is 30° C. to 110° C., and the cell voltage is 2V to 5V.

[0021] In some embodiments, the step of preparing the anolyte comprises:

[0022] The divalent cobalt salt and the first supporting electrolyte are dissolved in acetic acid to form the anolyte.

[0023] In some embodiments, the step of preparing the cathode liquid comprises:

[0024] The second supporting electrolyte is dissolved in acetic acid to form the cathode solution.

[0025] In some embodiments, the step of assembling the anolyte and the catholyte to form an electrolytic cell comprises:

[0026] placing the anolyte and the anode in an anode chamber, wherein the anode is disposed in the anolyte;

[0027] placing the catholyte and cathode in a cathode chamber, wherein the cathode is disposed in the catholyte;

[0028] The anolyte in the anode chamber and the catholyte in the cathode chamber are separated by a proton exchange membrane; and

[0029] The anode and the cathode are electrically connected. In some embodiments, the proton exchange membrane is a proton exchange membrane, and the proton exchange membrane includes nafion 115, nafion 117, N1110 or NC700;

[0030] In some embodiments, the anode includes a graphite electrode, a titanium electrode, a platinum electrode, or a glassy carbon electrode.

[0031] In some embodiments, the cathode comprises a platinum electrode, a stainless steel electrode, a graphite electrode, or a glassy carbon electrode.

[0032] In some embodiments, the divalent cobalt salt includes one or more of cobalt acetate, cobalt perchlorate hexahydrate, and cobalt tetrafluoroborate hexahydrate.

[0033] In some embodiments, the structural formula of the toluene derivative is shown in formula (I):

[0034] Wherein, R1 is -H, halogen, nitro, alkyl or alkoxy, and R2 is -H, alkyl or phenyl.

[0035] In some embodiments, when R2 is -H, the general formula for the oxidation reaction of toluene and / or its derivatives is as shown in Formula (II):

[0036] In some embodiments, when R2 is an alkyl group or a phenyl group, the general formula for the oxidation reaction of toluene and / or its derivatives is as shown in Formula (III):

[0037] In some embodiments, R1 is -H, -F, -Cl, nitro, methyl, tert-butyl, or methoxy, and R2 is -H, methyl, or phenyl.

[0038] Compared with traditional liquid-phase oxidation methods, the oxidation method provided in this application has the advantages of mild reaction conditions, low energy consumption and high safety, and is green and sustainable; and the yield of the oxidation products formed, especially aldehyde products, is higher than that of traditional oxidation methods.

[0039] In addition, during the electrolysis process, that is, during the electrochemical oxidation process, divalent cobalt ions (Co 2+ ) as an electrochemical mediator, thereby achieving mediated oxidation of toluene and / or its derivatives, that is, the anode first oxidizes divalent cobalt ions to trivalent cobalt ions (Co 3+ ), then Co 3+ Toluene and / or its derivatives are oxidized, thereby reducing the voltage required for the electrolysis process and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0041] FIG1 is a schematic diagram of a method for oxidizing toluene and / or its derivatives according to one embodiment. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0044] the term:

[0045] As used herein, the term "and / or" includes any one of two or more of the listed items, as well as any and all combinations of the listed items, including any combination of any two, any more, or all of the listed items. For example, "A and / or B" includes A, B, and the combination of A and B.

[0046] In this document, unless otherwise specified, "one or more" means any one of the listed items or any combination of the listed items. Similarly, "one or more" and other expressions that mean "one or more" are also understood in the same way unless otherwise specified.

[0047] As used herein, the terms "further," "further," "particularly," "for example," "such as," "example," and "for instance" are used for descriptive purposes to indicate that the preceding and following technical solutions are related in terms of their coverage, but should not be construed as limiting the preceding technical solution or the scope of protection herein. As used herein, unless otherwise specified, "A (such as B)" means that B is a non-limiting example of A, and it should be understood that A is not limited to B.

[0048] As used herein, "optionally," "optional," and "optional" mean optional, that is, any one of the two parallel options of "with" or "without." If multiple "optional" items appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" item is independent of the other. In this application, descriptions such as "optionally contain" and "optionally include" mean "containing or not containing." "Optional component X" means the presence or absence of component X, or the presence or absence of component X.

[0049] In this document, the terms "first," "second," "third," and "fourth," etc., are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first," "second," "third," and "fourth," etc., serve only as non-exhaustive enumeration and description and should not constitute a closed-ended limitation on quantity.

[0050] In this article, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0051] Herein, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is considered continuous and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows for broad inclusion of numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0052] In this document, if a method flow involves multiple steps, unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be performed in an order other than the order described. Moreover, any step can include multiple sub-steps or multiple stages, and these sub-steps or stages do not necessarily need to be completed at the same time, but can be performed at different times, and their execution order does not necessarily need to be sequential, but can be performed in rotation, alternation, or simultaneously with other steps or parts of sub-steps or stages of other steps.

[0053] Traditional liquid-phase oxidation methods suffer from harsh reaction conditions, poor safety, and high energy consumption. While some researchers have proposed electrochemical oxidation methods for ethylbenzene or tetralin, these methods are ineffective when used with toluene and / or its derivatives, which are more difficult to oxidize. Therefore, this application provides a method for oxidizing toluene and / or its derivatives to address these current challenges.

[0054] The present application provides a method for oxidizing toluene and / or its derivatives, comprising the following steps:

[0055] One or more components of toluene and its derivatives are electrolyzed by electrolysis to oxidize the toluene and / or its derivatives; wherein the anolyte used in the electrolysis contains divalent cobalt ions.

[0056] Compared with traditional liquid-phase oxidation methods, the oxidation method provided in this application has the advantages of mild reaction conditions, low energy consumption and high safety, and is green and sustainable; and the yield of the oxidation products formed, especially aldehyde products, is higher than that of traditional oxidation methods.

[0057] In addition, during the electrolysis process, that is, during the electrochemical oxidation process, divalent cobalt ions (Co 2+) as an electrochemical mediator, thereby achieving mediated oxidation of toluene and / or its derivatives, that is, the anode first oxidizes divalent cobalt ions to trivalent cobalt ions (Co 3+ ), then Co 3+ Toluene and / or its derivatives are oxidized, thereby reducing the voltage required for the electrolysis process and reducing energy consumption.

[0058] In some embodiments, the step of electrolyzing one or more components of toluene and its derivatives by electrolysis comprises:

[0059] Step S100: preparing an anolyte and a catholyte, wherein the anolyte contains divalent cobalt ions;

[0060] Step S200: assembling the anolyte and the catholyte to form an electrolytic cell, and adding one or more components of toluene and its derivatives to the anolyte; and

[0061] Step S300: electrolyzing one or more components of toluene and its derivatives through the electrolytic cell to oxidize the toluene and / or its derivatives.

[0062] In some embodiments, the anolyte further comprises a first supporting electrolyte and the catholyte comprises a second supporting electrolyte.

[0063] Furthermore, the concentrations of the first supporting electrolyte and the second supporting electrolyte refer to their concentrations immediately upon addition; the concentration of the first supporting electrolyte in the anolyte and the concentration of the second supporting electrolyte in the catholyte may be the same or different, and in one embodiment, are the same. It will be appreciated that as electrolysis proceeds, the concentrations of cations in the first supporting electrolyte in the anolyte and the second supporting electrolyte in the catholyte reach a dynamic equilibrium, maintaining substantially the same concentration, while the concentration of anions remains constant due to the barrier effect of the proton exchange membrane.

[0064] It is understood that the supporting electrolyte is an electrolyte that improves the conductivity of the electrolytic cell electrolyte, and itself does not participate in the electrochemical reaction. In the present application, the selection of the first supporting electrolyte and the second supporting electrolyte is not limited, and any supporting electrolyte known in the art can be selected. As an exemplary illustration, the first supporting electrolyte and the second supporting electrolyte can be independently selected from one or more of tetrabutylammonium acetate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate, tetraethylammonium tetrafluoroborate, tetraethylammonium perchlorate and lithium tetrafluoroborate. In one embodiment, the first supporting electrolyte and the second supporting electrolyte are identical.

[0065] In some embodiments, the step of preparing the anolyte comprises:

[0066] A divalent cobalt salt and a first supporting electrolyte are dissolved in acetic acid to form the anolyte.

[0067] In some embodiments, the divalent cobalt salt includes one or more of cobalt acetate, cobalt perchlorate hexahydrate, and cobalt tetrafluoroborate hexahydrate. In one embodiment, the divalent cobalt salt is cobalt acetate. The acetate in the cobalt acetate can coordinate with the cobalt ion, thereby making the cobalt species in the solution electrically neutral and more susceptible to oxidation at the anode.

[0068] In some embodiments, the concentration of divalent cobalt ions in the anolyte is 0.03 mol / L to 0.2 mol / L, for example, 0.04 mol / L, 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, and 0.18 mol / L; the concentration of the supporting electrolyte is 0.05 mol / L to 0.2 mol / L, for example, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, and 0.18 mol / L. By regulating the concentration of divalent cobalt ions within the above range, a higher yield can be achieved; and by regulating the concentration of the first supporting electrolyte within the above range, the conductivity of the solution can be ensured and the side reaction of acetic acid decarboxylation can be suppressed to a certain extent.

[0069] In some embodiments, the step of preparing the catholyte comprises:

[0070] The second supporting electrolyte is dissolved in acetic acid to form the catholyte.

[0071] In some embodiments, in the cathode solution, the concentration of the second supporting electrolyte is 0.05 mol / L to 0.2 mol / L, for example, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.18 mol / L.

[0072] It is understood that toluene derivatives refer to more complex products derived from toluene in which hydrogen atoms on the toluene are replaced by other atoms or atomic groups. In this application, the selection of toluene derivatives is not limited.

[0073] In some embodiments, the structural formula of the toluene derivative is shown in Formula (I):

[0074] Wherein, R1 is -H, halogen, nitro, alkyl or alkoxy, and R2 is -H, alkyl or phenyl. Specifically, the alkyl group may include a straight-chain alkyl group or a branched-chain alkyl group. For example, the straight-chain alkyl group may be a methyl group, and the branched-chain alkyl group may be a tert-butyl group.

[0075] In some embodiments, when R2 is -H, the general formula for the oxidation reaction of toluene and / or its derivatives is as shown in Formula (II):

[0076] In some embodiments, when R2 is an alkyl group or a phenyl group, the general formula for the oxidation reaction of toluene and / or its derivatives is as shown in Formula (III):

[0077] In some embodiments, R1 is -H, -F, -Cl, nitro, methyl, tert-butyl, or methoxy, and R2 is -H, methyl, or phenyl.

[0078] Furthermore, the toluene derivative may include one or more of p-fluorotoluene, tert-butyltoluene, m-chlorotoluene, ethylbenzene and diphenylmethane.

[0079] Taking toluene as an example, the process of electrochemically mediated oxidation reaction is shown in the following formula (II):

[0080] Principle: Using oxygen from air as the oxygen source and the catalysis of cobalt ions, toluene can be electrochemically oxidized under mild conditions of 30°C to 110°C at atmospheric pressure. This method does not require a high-temperature or high-pressure reaction environment, and the oxygen partial pressure in the reaction system is low, ensuring a safe process.

[0081] In some embodiments, the electrolysis temperature is 30°C to 110°C, for example, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C. In one embodiment, the electrolysis temperature is 60°C to 100°C.

[0082] It is understood that the cell voltage refers to the voltage applied between the two electrodes by an external power source to promote the electrode reaction between the two electrodes, that is, the voltage between the cathode and anode electrodes in the electrolytic cell. In some embodiments, the cell voltage for electrolysis is 2V to 5V, for example, 3V or 4V.

[0083] In some embodiments, in the anolyte, the concentration of toluene and / or its derivatives is 0.05 mol / L to 0.2 mol / L, for example, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.15 mol / L, 0.16 mol / L, 0.18 mol / L.

[0084] In some embodiments, the step of assembling the anolyte and the catholyte to form an electrolytic cell includes steps S201 to S202:

[0085] Step S201: placing the anolyte and the anode in the anolyte chamber, and placing the catholyte and the cathode in the cathode chamber, wherein the anolyte chamber and the cathode chamber are separated by a proton exchange membrane;

[0086] Step S202: electrically connecting the anode and the cathode.

[0087] In this application, the type of proton exchange membrane is not limited, and any proton exchange membrane commonly used in the electrolytic cell field can be selected. In some embodiments, the proton exchange membrane includes Nafion 115, Nafion 117, N1110, or NC700.

[0088] In this application, the anode and cathode are not limited and can be any electrode known in the art of electrolytic cells, for example, a metal electrode or a carbon electrode. For example, the anode includes a graphite electrode, a titanium electrode, a platinum electrode, or a glassy carbon electrode; the cathode includes a platinum electrode, a stainless steel electrode, a graphite electrode, or a glassy carbon electrode.

[0089] In some embodiments, after electrolysis, the process further includes separating and purifying the anolyte. It is understood that the purpose of separation and purification is mainly to separate and purify the toluene and / or its derivatives obtained from the anolyte.

[0090] Optionally, the separation and purification method includes extraction, distillation, and chromatography. The process conditions of extraction, distillation, and chromatography are not limited, as long as the toluene and / or its derivatives in the anolyte are completely extracted. The chromatography can specifically be column chromatography.

[0091] Referring to FIG. 1 , according to a specific embodiment, the method for oxidizing toluene and / or its derivatives includes:

[0092] 1) dissolving a divalent cobalt salt and a first supporting electrolyte in acetic acid to form an anolyte; dissolving a second supporting electrolyte in acetic acid to form a catholyte;

[0093] 2) placing a catholyte and a cathode in a cathode chamber, wherein the cathode is disposed in the catholyte, placing an anolyte and an anode in an anolyte chamber, wherein the anode is disposed in the anolyte, and separating the catholyte in the cathode chamber from the anolyte in the anolyte chamber using a proton exchange membrane;

[0094] 3) electrically connecting the cathode and the anode using an external power supply;

[0095] 4) adding one or more components of toluene and its derivatives to the anolyte and performing electrolysis to oxidize the toluene and / or its derivatives;

[0096] 5) Separating and purifying the anolyte after electrolysis in step 4).

[0097] The present application will be further described in detail below with reference to specific examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. For experimental methods in the following examples where specific conditions are not specified, reference should be made to the instructions provided in this application, or to experimental manuals or conventional conditions in the art, or to conditions recommended by the manufacturer, or to experimental methods known in the art.

[0098] In the following specific examples, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument testing accuracy or operational accuracy are allowed.

[0099] Example 1

[0100] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 42.1% and the yield of benzoic acid was 39.5%.

[0101] Example 2

[0102] The preparation method of Example 2 is basically the same as that of Example 1, except that the compositions of the cathode liquid and the anode liquid are different. The specific steps are as follows:

[0103] 0.27g of cobalt acetate and 0.49g of tetrabutylammonium tetrafluoroborate were dissolved in 15mL of acetic acid to form an anolyte. 0.49g of tetrabutylammonium tetrafluoroborate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber. The cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 35.4% and the yield of benzoic acid was 30.0%.

[0104] Example 3

[0105] The preparation method of Example 3 is basically the same as that of Example 1, except that the compositions of the cathode liquid and the anode liquid are different. The specific steps are as follows:

[0106] 0.27g of cobalt acetate and 0.34g of tetraethylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.34g of tetraethylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode chamber and the anode chamber were separated by a proton exchange membrane Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography analysis showed that the yield of benzaldehyde was 37.9% and the yield of benzoic acid was 36.6%.

[0107] Example 4

[0108] The preparation method of Example 4 is basically the same as that of Example 1, except that the compositions of the cathode liquid and the anode liquid are different. The specific steps are as follows:

[0109] 0.27g of cobalt acetate and 0.14g of lithium tetrafluoroborate were dissolved in 15mL of acetic acid to form an anolyte. 0.14g of lithium tetrafluoroborate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode chamber and the anode chamber were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 12.5% ​​and the yield of benzoic acid was 9.8%.

[0110] Example 5

[0111] The preparation method of Example 5 is basically the same as that of Example 1, except that the temperature of the electrolytic cell is controlled to be 30° C. The specific steps are as follows:

[0112] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode chamber and the anode chamber were separated by a proton exchange membrane Nafion 117. The temperature of the electrolytic cell was controlled at 30°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography analysis showed that the yield of benzaldehyde was 5.7% and the yield of benzoic acid was 1.3%.

[0113] Example 6

[0114] The preparation method of Example 6 is basically the same as that of Example 1, except that the proton exchange membrane NC700 is used instead of the proton exchange membrane nafion 117. The specific steps are as follows:

[0115] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode chamber and the anode chamber were separated by a proton exchange membrane NC700. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography analysis showed that the yield of benzaldehyde was 33.3% and the yield of benzoic acid was 29.1%.

[0116] Example 7

[0117] The preparation method of Example 7 is basically the same as that of Example 1, except that the compositions of the cathode liquid and the anode liquid are different. The specific steps are as follows:

[0118] 0.54g of cobalt acetate and 0.49g of tetrabutylammonium tetrafluoroborate were dissolved in 15mL of acetic acid to form an anolyte. 0.49g of tetrabutylammonium tetrafluoroborate was dissolved in 15mL of acetic acid to form a catholyte. Using an H-type electrolytic cell, the anolyte was placed in the anode chamber and the catholyte was placed in the cathode chamber, and the cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 40.4% and the yield of benzoic acid was 43.7%.

[0119] Example 8

[0120] The preparation method of Example 8 is basically the same as that of Example 1, except that the composition of the cathode liquid and the anode liquid and the cell voltage are different. The specific steps are as follows:

[0121] 0.27g of cobalt acetate and 0.98g of tetrabutylammonium tetrafluoroborate were dissolved in 15mL of acetic acid to form an anolyte. 0.98g of tetrabutylammonium tetrafluoroborate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber. The cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 2V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 34.2% and the yield of benzoic acid was 29.5%.

[0122] Example 9

[0123] The preparation method of Example 9 is basically the same as that of Example 1, except that the cell voltage is different. The specific steps are as follows:

[0124] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 5V for 6h to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 25.3% and the yield of benzoic acid was 33.1%.

[0125] Example 10

[0126] The preparation method of Example 10 is basically the same as that of Example 1, except that p-fluorotoluene is used instead of toluene. The specific steps are as follows:

[0127] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode compartment and the catholyte placed in the cathode compartment. The cathode and anode compartments were separated by a proton exchange membrane, Nafion 117. The cell temperature was controlled at 100°C, 0.15g of p-fluorotoluene was added to the anode compartment, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize p-fluorotoluene to form p-fluorobenzaldehyde and p-fluorobenzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis revealed a yield of 35.8% for p-fluorobenzaldehyde and 28.4% for p-fluorobenzoic acid.

[0128] Example 11

[0129] The preparation method of Example 11 is basically the same as that of Example 1, except that tert-butyltoluene is used instead of toluene. The specific steps are as follows:

[0130] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber. The cathode and anode chambers were separated by a proton exchange membrane, Nafion 117. The cell temperature was controlled at 100°C, 0.23g of tert-butyltoluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h. Tert-butyltoluene was oxidized to form tert-butylbenzaldehyde and tert-butylbenzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis revealed a 7.8% yield of tert-butylbenzaldehyde and an 89.9% yield of tert-butylbenzoic acid.

[0131] Example 12

[0132] The preparation method of Example 12 is basically the same as that of Example 1, except that m-chlorotoluene is used instead of toluene. The specific steps are as follows:

[0133] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode compartment and the catholyte placed in the cathode compartment. The cathode and anode compartments were separated by a proton exchange membrane, Nafion 117. The cell temperature was controlled at 100°C, 0.16g of m-chlorotoluene was added to the anode compartment, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize m-chlorotoluene to form m-chlorobenzaldehyde and m-chlorobenzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis revealed a 7.8% yield of m-chlorobenzaldehyde and an 89.9% yield of m-chlorobenzoic acid.

[0134] Example 13

[0135] The preparation method of Example 13 is basically the same as that of Example 1, except that ethylbenzene is used instead of toluene. The specific steps are as follows:

[0136] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. Using an H-type electrolytic cell, the anolyte was placed in the anode chamber and the catholyte was placed in the cathode chamber, with the cathode and anode chambers separated by a proton exchange membrane, Nafion 117. The cell temperature was controlled at 100°C, 0.15g of ethylbenzene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize ethylbenzene to form acetophenone. Ultra-high performance liquid chromatography revealed a yield of 59.9% for acetophenone.

[0137] Example 14

[0138] The preparation method of Example 14 is basically the same as that of Example 1, except that diphenylmethane is used instead of toluene. The specific steps are as follows:

[0139] 0.27g of cobalt acetate and 0.51g of tetrabutylammonium perchlorate were dissolved in 15mL of acetic acid to form an anolyte. 0.51g of tetrabutylammonium perchlorate was dissolved in 15mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber, and the cathode chamber and the anode chamber were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.27g of diphenylmethane was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4V for 6h to oxidize diphenylmethane to form benzophenone. Ultra-high performance liquid chromatography analysis showed that the yield of benzophenone was 54.7%.

[0140] Comparative Example 1

[0141] The preparation method of Comparative Example 1 is basically the same as that of Example 1, except that no cobalt acetate is added to the anolyte, that is, a pure electrochemical oxidation method is used. The specific steps are as follows:

[0142] 0.51 g of tetrabutylammonium perchlorate was dissolved in 15 mL of acetic acid to form an anolyte. 0.51 g of tetrabutylammonium perchlorate was dissolved in 15 mL of acetic acid to form a catholyte. An H-type electrolytic cell was used, with the anolyte placed in the anode chamber and the catholyte placed in the cathode chamber. The cathode chamber and the anode chamber were separated by a proton exchange membrane, Nafion 117. The temperature of the electrolytic cell was controlled at 100°C, 0.14 g of toluene was added to the anode chamber, and electrolysis was carried out at a cell voltage of 4 V for 6 hours to oxidize the toluene to form benzaldehyde and benzoic acid. Ultra-high performance liquid chromatography (UPLC) analysis showed that the yield of benzaldehyde was 12.5%, and the yield of benzoic acid was 10.8%.

[0143] The raw material ratio parameters in the preparation methods of Examples 1 to 14 and Comparative Example 1 are listed in Table 1 below:

[0144] Table 1

[0145] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0146] The above-described embodiments merely represent several embodiments of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A method for oxidizing toluene and / or its derivatives, characterized in that: The following steps are involved: One or more components of toluene and its derivatives are electrolyzed by electrolysis to oxidize the toluene and / or its derivatives; the anolyte used in the electrolysis contains divalent cobalt ions.

2. The method for oxidizing toluene and / or its derivatives according to claim 1, characterized in that: In the anolyte, the concentration of the divalent cobalt ions is 0.03 mol / L to 0.2 mol / L.

3. The method for oxidizing toluene and / or its derivatives according to claim 1 or 2, characterized in that: The step of electrolyzing one or more components in toluene and its derivatives by electrolysis comprises: preparing an anolyte and a catholyte, wherein the anolyte comprises divalent cobalt ions; Assembling the anolyte and the cathode solution to form an electrolytic cell, and adding one or more components of toluene and its derivatives to the anolyte; and One or more components of toluene and its derivatives are electrolyzed by the electrolytic cell to oxidize the toluene and / or its derivatives.

4. The method for oxidizing toluene and / or its derivatives according to claim 3, characterized in that: The anolyte further includes a first supporting electrolyte, and the catholyte includes a second supporting electrolyte.

5. The method for oxidizing toluene and / or its derivatives according to claim 4, characterized in that: The first supporting electrolyte and the second supporting electrolyte are independently selected from one or more of tetrabutylammonium acetate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate, tetraethylammonium tetrafluoroborate, tetraethylammonium perchlorate and lithium tetrafluoroborate.

6. The method for oxidizing toluene and / or its derivatives according to claim 4 or 5, characterized in that: In the anolyte, the concentration of the first supporting electrolyte is 0.05 mol / L to 0.2 mol / L.

7. The method for oxidizing toluene and / or its derivatives according to any one of claims 4 to 6, characterized in that: In the cathode liquid, the concentration of the second supporting electrolyte is 0.05 mol / L to 0.2 mol / L.

8. The method for oxidizing toluene and / or its derivatives according to any one of claims 1 to 7, characterized in that: In the anolyte, the concentration of toluene and / or its derivatives is 0.05 mol / L to 0.2 mol / L.

9. The method for oxidizing toluene and / or its derivatives according to any one of claims 1 to 8, characterized in that: The electrolysis temperature is 30°C to 110°C, and the cell voltage is 2V to 5V.

10. The method for oxidizing toluene and / or its derivatives according to any one of claims 4 to 7, characterized in that: The step of preparing the anolyte comprises: The divalent cobalt salt and the first supporting electrolyte are dissolved in acetic acid to form the anolyte.

11. The method for oxidizing toluene and / or its derivatives according to any one of claims 4 to 7, characterized in that: The step of preparing the cathode liquid comprises: The second supporting electrolyte is dissolved in acetic acid to form the cathode solution.

12. The method for oxidizing toluene and / or its derivatives according to any one of claims 4 to 7, characterized in that: The step of assembling the anolyte and the catholyte to form an electrolytic cell comprises: placing the anolyte and the anode in an anode chamber, wherein the anode is disposed in the anolyte; placing the catholyte and the cathode in a cathode chamber, wherein the cathode is disposed in the catholyte; The anolyte in the anode chamber and the catholyte in the cathode chamber are separated by a proton exchange membrane; and The anode and the cathode are electrically connected.

13. The method for oxidizing toluene and / or its derivatives according to claim 12, characterized in that: The proton exchange membrane is a proton exchange membrane, and the proton exchange membrane includes nafion115, nafion117, N1110 or NC700.

14. The method for oxidizing toluene and / or its derivatives according to claim 12 or 13, characterized in that: The anode includes a graphite electrode, a titanium electrode, a platinum electrode or a glassy carbon electrode.

15. The method for oxidizing toluene and / or its derivatives according to any one of claims 12 to 14, characterized in that: The cathode includes a platinum electrode, a stainless steel electrode, a graphite electrode or a glassy carbon electrode.

16. The method for oxidizing toluene and / or its derivatives according to claim 10, characterized in that: The divalent cobalt salt includes one or more of cobalt acetate, cobalt perchlorate hexahydrate and cobalt tetrafluoroborate hexahydrate.

17. The method for oxidizing toluene and / or its derivatives according to any one of claims 1 to 16, characterized in that: The structural formula of the toluene and / or its derivatives is shown in formula (I): Wherein, R1 is -H, halogen, nitro, alkyl or alkoxy, and R2 is -H, alkyl or phenyl.

18. The method for oxidizing toluene and / or its derivatives according to claim 17, characterized in that: When R2 is -H, the general formula of the oxidation reaction of toluene and / or its derivatives is as shown in formula (II): When R2 is an alkyl group or a phenyl group, the general formula for the oxidation reaction of toluene and / or its derivatives is as shown in formula (III):

19. The method for oxidizing toluene and / or its derivatives according to claim 18, characterized in that: R1 is -H, -F, -Cl, nitro, methyl, tert-butyl or methoxy, and R2 is -H, methyl or phenyl.

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