A method for synthesizing 1-aminoanthraquinone by electrocatalytic hydrogenation using palladium nanocluster catalyst

Abstract

The present invention discloses an application of a sequencing batch electrochemical hydrogenation system. The sequencing batch electrochemical hydrogenation system uses a titanium sheet as an anode and a platinum sheet as a cathode, and the entire system can be operated in a beaker. The sequencing batch electrochemical hydrogenation system proposed by the present invention has simple equipment, rapid reaction, mild reaction conditions, and is environmentally friendly. Palladium nanoclusters are used in conjunction with a sequencing batch electrochemical hydrogenation system to reduce 1-nitroanthraquinone to prepare 1-aminoanthraquinone. The palladium nanoclusters are not only good catalysts for catalyzing the production of hydrogen at the cathode, but also have the ability to absorb hydrogen, which can also gather more hydrogen produced by electrolysis, reduce the escape of hydrogen in the system, improve the efficiency of electrochemical hydrogenation, and achieve rapid and efficient reduction of 1-nitroanthraquinone to prepare 1-aminoanthraquinone.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, and in particular to a method for synthesizing 1-aminoanthraquinone by electrocatalytic hydrogenation using a palladium nanocluster catalyst. Background Art

[0002] Among many dyes, anthraquinone dyes have become one of the most commonly used dyes due to their advantages such as high light fastness, good thermal stability and bright colors. They are widely used in the fields of inks, optoelectronic materials, etc. 1-aminoanthraquinone, as an important intermediate for the synthesis of anthraquinone dyes, is a key raw material for the production of dyes such as bromoamic acid, disperse red RLZ, and reactive brilliant blue X-BR. Therefore, the development of a simple and efficient process for the synthesis of 1-aminoanthraquinone undoubtedly has extremely high economic value and broad application prospects. At present, the commonly used industrial production process in China is to use 1-nitroanthraquinone as a raw material, reduce it with hydrosulfite and alkali sulfide, and then oxidize it to obtain 1-aminoanthraquinone. Although this method has stable product quality and simple operation, it will produce a large amount of three wastes and pollute the environment. In addition, the ammonolysis method, catalytic hydrogenation reduction method and CO / H2O reduction method can all use 1-nitroanthraquinone to prepare 1-aminoanthraquinone. There are two ways of ammonolysis: one is to add 1-nitroanthraquinone to ammonia water and perform ammonolysis under high temperature and pressure; the other is to use liquid ammonia in an organic solvent. The former method affects industrial application because of the explosive ammonium nitrite generated in the process. The latter method produces amino compounds, nitrogen and water in the production process, which belongs to clean production and has good prospects. The catalytic hydrogenation reduction method usually uses transition metals such as palladium and nickel and their compounds as catalysts, and uses hydrogen as a reducing agent to reduce nitro compounds to prepare amino compounds. Although catalytic hydrogenation is green and clean, and the product purity is high, hydrogen is not only flammable and explosive, but also reduces the carbonyl group of anthraquinone while reducing the nitro group. The amount of catalyst required for the reaction is large, and the product and catalyst need to be separated. The CO / H2O reduction method is a method of reducing the nitro group to form an amino group by introducing CO under the action of a catalyst. This method can selectively reduce the nitro group on the aromatic ring without destroying the carbonyl group in the anthraquinone structure, but the reducing agent CO is highly toxic and the required catalyst synthesis method is more complicated or more expensive.

[0003] The present invention provides an electrochemical reduction method which can be used to prepare 1-aminoanthraquinone. The method has the advantages of simple operation, easy reaction control, simplified reactor, high product purity, high yield and environmental friendliness. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an application of a sequencing batch electrochemical hydrogenation system for reducing 1-nitroanthraquinone to prepare 1-aminoanthraquinone, the method having simple technical operation, fast reaction rate and good substrate reduction effect. Moreover, the reaction system can be built in a beaker.

[0005] In order to solve the above problems, the technical solution provided by the present invention is as follows: a method for synthesizing 1-aminoanthraquinone by electrocatalytic hydrogenation using a palladium nanocluster catalyst, comprising the following steps:

[0006] (1) adding N-methylpyrrolidone into a reactor to dissolve 1-nitroanthraquinone;

[0007] (2) Adding Na2SO4 and ultrapure water to another reactor, stirring and dissolving, and then pouring the resulting solution into the reactor in step (1) as the system electrolyte solution;

[0008] (3) Adding palladium nanoclusters as catalysts for hydrogen production at the cathode;

[0009] (4) inserting the cathode and anode into the reactor;

[0010] (5) 1-Aminoanthraquinone is prepared by cathode hydrogenation reduction of 1-nitroanthraquinone under a certain applied voltage.

[0011] Preferably, in step (4), the anode is a titanium sheet and the cathode is a platinum sheet; or the anode is a platinum sheet and the cathode is a titanium sheet.

[0012] Preferably, the preparation method of the palladium nanocluster catalyst comprises the following steps:

[0013] (1) adding sodium chloropalladate aqueous solution into ultrapure water;

[0014] (2) adding an aqueous solution of 2-hydroxy-4-methylthiobutyric acid to the sodium chloropalladate solution in step (1), and stirring to obtain a mixed solution;

[0015] (3) successively adding sodium hydroxide solution and sodium borohydride solution to the mixed solution obtained in step (2), and stirring to obtain the product.

[0016] Preferably, the mass ratio of the catalyst volume to 1-nitroanthraquinone (ml:mg) is 0-0.4:1.

[0017] Preferably, the voltage is 0-10V, and direct current is used.

[0018] Preferably, the mass ratio of the volume of N-methylpyrrolidone to 1-nitroanthraquinone (ml:mg) is 10-30:25, and the mass ratio of the mass of Na2SO4, the volume of ultrapure water to 1-nitroanthraquinone (mg:mL:mg) is 25-30:40:25.

[0019] Preferably, in the palladium nanocluster catalyst: the sodium chloropalladate ultrapure water solution is a 1.5mM-2.5mM aqueous solution, the 2-hydroxy-4-methylthiobutyric acid solution is a 4mM-6mM aqueous solution, the sodium hydroxide solution is a 0.5M-1.5M aqueous solution, and the sodium borohydride solution is a 105mM-125mM aqueous solution; the volume ratio of sodium chloropalladate ultrapure water solution: 2-hydroxy-4-methylthiobutyric acid solution: sodium hydroxide solution: sodium borohydride solution is 26:20:3:1.

[0020] The principle of the present invention is as follows:

[0021] Under the action of an applied voltage, the 1-nitroanthraquinone near the platinum sheet (cathode) in the solution receives electrons and is reduced to 1-aminoanthraquinone, and part of the precipitated 1-nitroanthraquinone will form flocs suspended in the solution, which can also undergo a reduction reaction by contacting the platinum sheet (cathode). The cathode produces hydrogen by electrolyzing water, and the addition of palladium nanocluster catalysts can accelerate the rate of hydrogen production at the cathode, playing a role in assisting the electrochemical hydrogenation reduction of 1-nitroanthraquinone.

[0022] The advantages of the present invention are:

[0023] (1) The sequencing batch electrochemical hydrogenation system proposed in the present invention has simple equipment, rapid reaction, mild reaction conditions, and is environmentally friendly, and provides a practical operating method for the electrochemical preparation of 1-aminoanthraquinone.

[0024] (2) The present invention uses palladium nanoclusters as catalysts, which not only effectively accelerates the system's cathode hydrogen production but also stores part of the generated hydrogen, reduces hydrogen escape in the system, and improves the reaction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a comparison chart of the yield of 1-aminoanthraquinone prepared by reducing 1-nitroanthraquinone in the sequencing batch electrochemical hydrogenation system in Example 1 and Comparative Example 1 when different materials are used as cathodes;

[0026] Figure 2 This is a comparison chart of the yield of 1-aminoanthraquinone prepared by reducing 1-nitroanthraquinone in the sequencing batch electrochemical hydrogenation system at different applied voltages in Example 1 and Comparative Example 2;

[0027] Figure 3 This is a comparison chart of the yield of 1-aminoanthraquinone prepared by reducing 1-nitroanthraquinone in the sequencing batch electrochemical hydrogenation system at different palladium nanocluster dosages in Example 1 and Comparative Example 3. DETAILED DESCRIPTION

[0028] The present invention is described below with reference to examples, but the present invention is not limited thereto. In the art, simple replacement or improvement made by technicians in the field to the present invention belongs to the technical solution protected by the present invention.

[0029] Embodiment 1:

[0030] A method for reducing 1-nitroanthraquinone to prepare 1-aminoanthraquinone by a sequencing batch electrochemical hydrogenation system of the present invention is specifically described as follows:

[0031] (1) Pour 20 mL of NMP solution into a 100 mL beaker, weigh 25 mg of 1-nitroanthraquinone, add it, and stir to fully dissolve. Take another beaker, pour 40 mL of ultrapure water, weigh 28.4 mg of Na2SO4, add it, and stir to fully dissolve.

[0032] (2) Pour the prepared Na2SO4 solution into a 100 mL beaker, add 4 mL of palladium nanoclusters, stir to fully mix, and then insert electrodes, with the anode being a titanium sheet and the cathode being a platinum sheet, and the applied voltage being 4 V.

[0033] The preparation method of the palladium nanocluster catalyst comprises the following steps:

[0034] (1) Add 25 mL of 20 mM sodium chloropalladate aqueous solution to 235 mL of ultrapure water to a final volume of 260 mL;

[0035] (2) adding 200 mL of 5 mM 2-hydroxy-4-methylthiobutyric acid (MHA) solution to the sodium chloropalladate solution in step (1), and stirring for 2 min to obtain a mixed solution;

[0036] (3) Add 30 mL of 1 M sodium hydroxide solution and 10 mL of 114 mM sodium borohydride solution to the mixed solution obtained in step (2) in sequence, stir for 3 h, and then place in a refrigerator at 8° C. for later use.

[0037] (3) A zero sample was taken before power was turned on, and samples were taken every 20 minutes during the operation. After the experiment, the 1-aminoanthraquinone content in the sample was determined by high performance liquid chromatography. The yield was about 2.7 mg / h after 60 minutes of operation. After the reaction, the 1-aminoanthraquinone content was about 366 mg / L, and the conversion rate was about 99.2%.

[0038] Comparative Example 1:

[0039] The difference between this comparative example and Example 1 is that the cathode used in this comparative example is a titanium sheet and the anode is a platinum sheet.

[0040] Comparative Example 2:

[0041] The difference between this comparative example and Example 1 is that the applied voltages are 0V, 3V, 5V and 10V respectively.

[0042] Comparative Example 3:

[0043] The difference between this comparative example and Example 1 is that the dosage of the palladium nanocluster catalyst is 0 mL, 2 mL, 5 mL and 10 mL respectively.

[0044] The test data of Example 1 and Comparative Example 1 are as follows Figure 1 As shown. Figure 1 It can be seen that the reduction effect of the system when the platinum sheet is used as the cathode is slightly higher than that when the titanium sheet is used as the cathode. The main reason is that the resistivity of platinum is much smaller than that of titanium, which is more conducive to electron transfer. However, when both are used as cathodes, the system has a good reduction effect on 1-nitroanthraquinone, which shows that there are many choices for cathode materials in the sequencing batch electrochemical hydrogenation system.

[0045] The test data of Example 1 and Comparative Example 2 are as follows Figure 2 As shown. Figure 2 It can be seen that the reduction rate of 1-nitroanthraquinone is almost zero when no electricity is applied. It can be seen that the main reaction power of this method for preparing 1-aminoanthraquinone comes from the applied voltage. When the voltage is 10V, 1-nitroanthraquinone cannot be correctly reduced to 1-aminoanthraquinone but generates other products. The reason is that the voltage is too large and side reactions occur. When the voltage is 3-5V, the yield of 1-aminoanthraquinone gradually increases, but the yields of 4V and 5V are significantly higher than 3V. According to preliminary experiments, the reaction rate of 5V shows a downward trend after a period of time, while the reaction rate of 4V is relatively stable. In the later stage, it can gradually catch up with the yield of 5V. The final conversion rates of the two are close, so 4V can be selected for reaction to reduce energy consumption.

[0046] The test data of Example 1 and Comparative Example 3 are as follows Figure 3 As shown. Figure 3 It can be seen that adding an appropriate amount of catalyst can improve the reduction rate of 1-nitroanthraquinone in the system, while excessive addition will affect the reaction. The reason is that adding a large amount of catalyst will reduce the concentration of the substrate in the system, reduce the contact between the cathode and the substrate, and is not conducive to the transfer of electrons; in addition, excessive palladium nanoclusters may absorb a large amount of hydrogen generated by the cathode, hindering the reaction of the substrate with it, and affecting the reduction effect.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for synthesizing 1-aminoanthraquinone by electrocatalytic hydrogenation using a palladium nanocluster catalyst, characterized in that: The following steps are involved: (1) adding N-methylpyrrolidone into a reactor to dissolve 1-nitroanthraquinone; (2) Adding Na2SO4 and ultrapure water to another reactor, stirring and dissolving, and then pouring the resulting solution into the reactor in step (1) as the system electrolyte solution; (3) adding palladium nanoclusters as a catalyst for cathode hydrogen production; the mass ratio of the catalyst volume to 1-nitroanthraquinone is 0.08-0.2 ml: 1 mg; (4) inserting a cathode and an anode into a reactor; the anode is a titanium sheet and the cathode is a platinum sheet; or the anode is a platinum sheet and the cathode is a titanium sheet; (5) Producing 1-aminoanthraquinone by cathode hydrogenation reduction of 1-nitroanthraquinone under a certain applied voltage; the voltage is 3 to 5 V, and direct current is used.

2. The method according to claim 1, characterized in that The preparation method of the palladium nanocluster catalyst comprises the following steps: (1) adding sodium chloropalladate aqueous solution into ultrapure water; (2) adding an aqueous solution of 2-hydroxy-4-methylthiobutyric acid to the sodium chloropalladate solution in step (1), and stirring to obtain a mixed solution; (3) successively adding sodium hydroxide solution and sodium borohydride solution to the mixed solution obtained in step (2), and stirring to obtain the product.

3. The method according to claim 1, characterized in that The mass ratio of the volume of N-methylpyrrolidone to 1-nitroanthraquinone is 10-30 ml:25 mg, and the mass ratio of the mass of Na2SO4, the volume of ultrapure water to 1-nitroanthraquinone is 25-30 mg:40 ml:25 mg.

4. The method according to claim 2, characterized in that In the palladium nanocluster catalyst: the sodium chloropalladate ultrapure water solution is a 1.5mM-2.5mM aqueous solution, the 2-hydroxy-4-methylthiobutyric acid solution is a 4mM-6mM aqueous solution, the sodium hydroxide solution is a 0.5M-1.5M aqueous solution, and the sodium borohydride solution is a 105mM-125mM aqueous solution; the volume ratio of the sodium chloropalladate ultrapure water solution: the 2-hydroxy-4-methylthiobutyric acid solution: the sodium hydroxide solution: the sodium borohydride solution is 26:20:3:1.

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