A method for preparing a selective debenzylization catalyst

Abstract

The application discloses a preparation method of a selective debenzylization catalyst, and comprises the following steps: step one, washing activated carbon with deionized water until neutral, filtering, and drying to obtain treated activated carbon; step two, mixing hydrochloric acid solution and nitric acid solution to obtain a mixed acid solution; step three, dissolving a palladium source in the mixed acid solution to obtain a mixed acid solution containing an active component; step four, placing the treated activated carbon in the mixed acid solution containing the active component, and stirring until uniformly dispersed; and step five, continuously stirring the dispersed system to stabilize, filtering, and drying to obtain the selective debenzylization catalyst. The preparation method of the selective debenzylization catalyst can effectively avoid the rapid reduction of the active component to an element at the initial stage of impregnation, and the element continues to grow as a metal nucleus and forms agglomeration with the impregnation, so that the surface active component of the obtained catalyst is more uniformly dispersed, and the activity and selectivity are higher in the selective debenzylization reaction.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of catalysis technology, and particularly relates to a preparation method of a selective debenzyl catalyst. BACKGROUND

[0002] Organic synthesis is often a multi-step reaction. Due to the presence of functional groups in raw materials, side reactions often occur. Protecting the functional groups and removing the protecting groups at the end of the reaction is one of the effective means to avoid the above-mentioned side reactions. For example, the -N group in free amine is unstable and needs to be protected by benzyl during the reaction, and the benzyl is removed to obtain a free amino group again after the reaction.

[0003] Pd / C catalyst is a widely used benzyl removal catalyst, which has a significant catalytic effect in catalyzing debenzyl reaction. However, the current Pd / C catalyst still cannot avoid the occurrence of undesirable side reactions, such as the often accompanied dehalogenation process. Therefore, providing a catalyst with high selective debenzyl is the key to solving the above technical problems. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a preparation method of a selective debenzyl catalyst to overcome the shortcomings of the prior art. The preparation method of the selective debenzyl catalyst of the present application comprises placing activated carbon in a mixed acid solution containing active components for stabilization, which can effectively avoid the rapid reduction of active components to elemental substances by the carrier at the initial stage of impregnation, and then the elemental substances continue to grow as metal nuclei and form agglomeration as the impregnation proceeds. The catalyst prepared by the method of the present application has more uniform dispersion of active components on the surface, and has higher activity and selectivity in selective debenzyl reaction.

[0005] To solve the above technical problems, the technical solution adopted by the present application is: a preparation method of a selective debenzyl catalyst, characterized in that it comprises:

[0006] Step one, washing the activated carbon with deionized water until neutral, filtering, and drying to less than 1wt% of water content to obtain treated activated carbon;

[0007] Step two, mixing a hydrochloric acid solution and a nitric acid solution to obtain a mixed acid solution;

[0008] Step three, dissolving a palladium source in the mixed acid solution of step two to obtain a mixed acid solution containing active components;

[0009] Step four, placing the treated activated carbon of step one in the mixed acid solution containing active components of step three and stirring until uniform dispersion;

[0010] Step five, the dispersed system of step four is continuously stirred to be stable, filtered to obtain the post-stabilized material, and the post-stabilized material is dried to have water content <1 wt% to obtain the selective debenzylization catalyst.

[0011] The selective debenzylization catalyst preparation method has the characteristics that in step one, the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000 m 2 / g.

[0012] The selective debenzylization catalyst preparation method has the characteristics that in step two, the mass of the nitric acid solution is 4 times the mass of the hydrochloric acid solution, the mass percentage of the hydrochloric acid solution is 1%-20%, and the mass percentage of the nitric acid solution is 1%-20%.

[0013] The selective debenzylization catalyst preparation method has the characteristics that in step two, the mass of the nitric acid solution is 4 times the mass of the hydrochloric acid solution, the mass percentage of the hydrochloric acid solution is 1%-20%, and the mass percentage of the nitric acid solution is 1%-20%.

[0014] The selective debenzylization catalyst preparation method has the characteristics that in step two, the mass of the nitric acid solution is 4 times the mass of the hydrochloric acid solution, the mass percentage of the hydrochloric acid solution is 1%-20%, and the mass percentage of the nitric acid solution is 1%-20%.

[0015] The selective debenzylization catalyst preparation method has the characteristics that in step three, the palladium source includes palladium chloride, palladium nitrate or potassium chloropalladite; and in step three, the mass of the mixed acid solution is 80-200 times the mass of the palladium.

[0016] The selective debenzylization catalyst preparation method has the characteristics that in step four, the mass of the mixed acid solution containing the active component is 4-10.5 times the mass of the treated activated carbon.

[0017] The selective debenzylization catalyst preparation method has the characteristics that in step four, the mass of the mixed acid solution containing the active component is 4-10.5 times the mass of the treated activated carbon.

[0018] The selective debenzylization catalyst preparation method has the characteristics that in step five, the time of the continuous stirring is 2-24 h.

[0019] The selective debenzylization catalyst preparation method has the characteristics that in step five, the time of the continuous stirring is 2-24 h.

[0020] The reaction equation of the selective debenzylization catalyst preparation method is as follows:

[0021]

[0022] Compared with the prior art, the selective debenzylization catalyst preparation method has the following advantages:

[0023] 1. The preparation method of the selective debenzyl catalyst of the present application is creatively based on the influence of the reduction stage of the active component in the impregnation reaction process of the active component and the carrier on the performance of the product catalyst, and provides a method for preparing the selective debenzyl catalyst which can effectively avoid premature and rapid reduction of the catalyst. The catalyst obtained by using the preparation method comprising the limited pre-reduction has the characteristics of significantly improved activity and selectivity.

[0024] 2. The preparation method of the selective debenzyl catalyst of the present application comprises placing the activated carbon in a mixed acid solution containing the active component for stabilization, which can effectively avoid reduction of the active component to an element by the carrier at the initial stage of impregnation, avoid agglomeration, and make the active component more uniformly dispersed, so that the obtained selective debenzyl catalyst has higher activity and selectivity.

[0025] 3. The preparation method of the selective debenzyl catalyst of the present application comprises mixing a nitric acid solution and a hydrochloric acid solution to prepare a mixed acid solution, which is used as an impregnation and stabilization reaction system of the active component on the carrier activated carbon, so as to effectively increase the surface acid sites of the product catalyst and promote the hydrogenolysis to proceed in the direction of debenzyl reaction.

[0026] 4. Preferably, in the preparation method of the selective debenzyl catalyst of the present application, the mass percentage content of the hydrochloric acid solution is 3% to 10%, the mass percentage content of the nitric acid solution is 10% to 20%, the mass of the mixed acid solution is 5 to 8 times the mass of the treated activated carbon, and the stabilization and impregnation time is 2 to 8 hours. By using the method of the present application, the selective debenzyl catalyst is obtained under the above limited acid mass percentage content, raw material ratio and reaction parameters, and the selectivity can be as high as 99%.

[0027] The technical solutions of the present application will be further described in detail below in combination with examples. DETAILED DESCRIPTION

[0028] Example 1

[0029] The present embodiment provides a preparation method of a selective debenzyl catalyst, which comprises:

[0030] Step one, wash the activated carbon with deionized water until neutral, filter, and dry in an oven at 120°C until the water content is <1wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200 to 400 mesh, and the specific surface area is >1000m 2 / g;

[0031] Step two, mix 100g of a hydrochloric acid solution with a mass percentage content of 10% and 400g of a nitric acid solution with a mass percentage content of 10% to obtain a mixed acid solution;

[0032] Step three, dissolve 5g of palladium chloride containing palladium in the mixed acid solution in step two to obtain a mixed acid solution containing an active component;

[0033] Step four, 95g of the treated activated carbon in step one is placed in the mixed acid solution containing active components in step three, and stirred at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0034] Step five, the dispersed system in step four is continuously stirred for 8h to stabilize, filtered, and the stabilized material is placed in an oven at 105°C to dry to a water content of <1wt%, to obtain a selective debenzyl catalyst.

[0035] Example 2

[0036] The present example provides a method for preparing a selective debenzyl catalyst, comprising:

[0037] Step one, the activated carbon is washed with deionized water until neutral, filtered, and dried in an oven at 120°C to a water content of <1wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000m 2 / g;

[0038] Step two, 100g of a 10wt% hydrochloric acid solution and 400g of a 10wt% nitric acid solution are mixed to obtain a mixed acid solution;

[0039] Step three, 5g of palladium chloride containing palladium is dissolved in the mixed acid solution in step two to obtain a mixed acid solution containing active components;

[0040] Step four, 95g of the treated activated carbon in step one is placed in the mixed acid solution containing active components in step three, and stirred at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0041] Step five, the dispersed system in step four is continuously stirred for 8h to stabilize, filtered, and the stabilized material is placed in an oven at 105°C to dry to a water content of <1wt%, to obtain a selective debenzyl catalyst.

[0042] Example 3

[0043] The present example provides a method for preparing a selective debenzyl catalyst, comprising:

[0044] Step one, the activated carbon is washed with deionized water until neutral, filtered, and dried in an oven at 120°C to a water content of <1wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000m 2 / g;

[0045] Step two, 100g of a 10wt% hydrochloric acid solution and 400g of a 10wt% nitric acid solution are mixed to obtain a mixed acid solution;

[0046] Step three, dissolve palladium chloride containing 5g palladium into the mixed acid solution described in step two to obtain a mixed acid solution containing active components;

[0047] Step four, place 95g of the treated activated carbon described in step one into the mixed acid solution containing active components described in step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0048] Step five, continue stirring the system after dispersion in step four for 24h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in an oven at 105°C to dry until the water content is <1wt%, and obtain the selective debenzylation catalyst.

[0049] Example 4

[0050] The example provides a method for preparing a selective debenzylation catalyst, comprising:

[0051] Step one, wash the activated carbon with deionized water until neutral, filter, and dry in an oven at 120°C until the water content is <1wt%, and obtain the treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000m 2 / g;

[0052] Step two, mix 100g of a 10wt% hydrochloric acid solution and 400g of a 20wt% nitric acid solution to obtain a mixed acid solution;

[0053] Step three, dissolve palladium chloride containing 5g palladium into the mixed acid solution described in step two to obtain a mixed acid solution containing active components;

[0054] Step four, place 95g of the treated activated carbon described in step one into the mixed acid solution containing active components described in step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0055] Step five, continue stirring the system after dispersion in step four for 24h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in an oven at 105°C to dry until the water content is <1wt%, and obtain the selective debenzylation catalyst.

[0056] Example 5

[0057] The example provides a method for preparing a selective debenzylation catalyst, comprising:

[0058] Step one, wash the activated carbon with deionized water until neutral, filter, and dry in an oven at 120°C until the water content is <1wt%, and obtain the treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000m 2 / g;

[0059] Step two, mix 100 g of 3.5% hydrochloric acid solution and 400 g of 10% nitric acid solution to obtain a mixed acid solution;

[0060] Step three, dissolve 5 g of palladium chloride containing palladium in the mixed acid solution of step two to obtain a mixed acid solution containing active components;

[0061] Step four, place 95 g of the treated activated carbon of step one in the mixed acid solution containing active components of step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0062] Step five, continue to stir the dispersed system of step four for 8 h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in an oven at 105°C to dry to less than 1 wt% water content to obtain a selective debenzylization catalyst.

[0063] Example 6

[0064] The present example provides a method for preparing a selective debenzylization catalyst, comprising:

[0065] Step one, wash the activated carbon with deionized water until neutral, filter, and dry in an oven at 120°C to less than 1 wt% water content to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is greater than 1000 m 2 / g;

[0066] Step two, mix 150 g of 10% hydrochloric acid solution and 600 g of 10% nitric acid solution to obtain a mixed acid solution;

[0067] Step three, dissolve 5 g of palladium chloride containing palladium in the mixed acid solution of step two to obtain a mixed acid solution containing active components;

[0068] Step four, place 95 g of the treated activated carbon of step one in the mixed acid solution containing active components of step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0069] Step five, continue to stir the dispersed system of step four for 2 h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in an oven at 105°C to dry to less than 1 wt% water content to obtain a selective debenzylization catalyst.

[0070] Example 7

[0071] The present example provides a method for preparing a selective debenzylization catalyst, comprising:

[0072] Step one, wash the activated carbon with deionized water until neutral, filter, and bake in a 120°C oven until the water content is <1 wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000 m 2 / g;

[0073] Step two, mix 100 g of a 10% mass percentage hydrochloric acid solution and 400 g of a 10% mass percentage nitric acid solution to obtain a mixed acid solution;

[0074] Step three, dissolve 5 g of palladium nitrate containing palladium in the mixed acid solution described in step two to obtain a mixed acid solution containing active components;

[0075] Step four, place 95 g of the treated activated carbon described in step one in the mixed acid solution containing active components described in step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0076] Step five, continue to stir the dispersed system of step four for 6 h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in a 105°C oven until the water content is <1 wt% to obtain a selective debenzylization catalyst.

[0077] Example 8

[0078] The present embodiment provides a method for preparing a selective debenzylization catalyst, comprising:

[0079] Step one, wash the activated carbon with deionized water until neutral, filter, and bake in a 120°C oven until the water content is <1 wt% to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is >1000 m 2 / g;

[0080] Step two, mix 150 g of a 10% mass percentage hydrochloric acid solution and 600 g of a 10% mass percentage nitric acid solution to obtain a mixed acid solution;

[0081] Step three, dissolve 5 g of potassium chloropalladite containing palladium in the mixed acid solution described in step two to obtain a mixed acid solution containing active components;

[0082] Step four, place 95 g of the treated activated carbon described in step one in the mixed acid solution containing active components described in step three, and stir at room temperature until evenly dispersed; the room temperature is 20-25°C;

[0083] Step five, continue to stir the dispersed system of step four for 8 h to stabilize, filter, and obtain the stabilized material, and place the stabilized material in a 105°C oven until the water content is <1 wt% to obtain a selective debenzylization catalyst.

[0084] Example 9

[0085] The embodiment provides a preparation method of a selective debenzylization catalyst, which comprises the following steps:

[0086] Step one, washing activated carbon with deionized water until neutral, filtering, and baking in a 120 DEG C oven until the water content is less than 1 wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is greater than 1000 m 2 / g;

[0087] Step two, mixing 80 g of a 1 wt% hydrochloric acid solution and 320 g of a 1 wt% nitric acid solution to obtain a mixed acid solution;

[0088] Step three, dissolving 5 g of palladium chloride containing palladium in the mixed acid solution in step two to obtain a mixed acid solution containing an active component;

[0089] Step four, placing 95 g of the treated activated carbon in step one into the mixed acid solution containing the active component in step three, and stirring at room temperature until uniformly dispersed; the room temperature is 20-25 DEG C;

[0090] Step five, continuing to stir the system after dispersion in step four for 12 h to stabilize, filtering, and obtaining a stabilized material; and placing the stabilized material in a 105 DEG C oven until the water content is less than 1 wt%, to obtain a selective debenzylization catalyst.

[0091] Example 10

[0092] The embodiment provides a preparation method of a selective debenzylization catalyst, which comprises the following steps:

[0093] Step one, washing activated carbon with deionized water until neutral, filtering, and baking in a 120 DEG C oven until the water content is less than 1 wt%, to obtain treated activated carbon; the particle size of the activated carbon is 200-400 mesh, and the specific surface area is greater than 1000 m 2 / g;

[0094] Step two, mixing 200 g of a 20 wt% hydrochloric acid solution and 800 g of a 20 wt% nitric acid solution to obtain a mixed acid solution;

[0095] Step three, dissolving 5 g of palladium chloride containing palladium in the mixed acid solution in step two to obtain a mixed acid solution containing an active component;

[0096] Step four, placing 95 g of the treated activated carbon in step one into the mixed acid solution containing the active component in step three, and stirring at room temperature until uniformly dispersed; the room temperature is 20-25 DEG C;

[0097] Step five, the dispersion system of step four is continuously stirred for 20h to be stable, filtered to obtain the post-stabilization material, and the post-stabilization material is placed in an oven at 105℃ to be baked until the water content is less than 1wt%, to obtain the selective debenzylation catalyst.

[0098] Performance evaluation

[0099] The performance of the catalysts prepared in Examples 1-10 of the present application is evaluated, and the evaluation method specifically includes:

[0100] Into a 250ml stainless steel autoclave, 5.0g of 4-chloro-N,N-dibenzyl aniline, 100ml of tetrahydrofuran and 0.25g of the catalyst are sequentially added, the gas in the autoclave is replaced with nitrogen and hydrogen three times in turn, hydrogen is continuously introduced until the pressure in the autoclave is 0.25MPa, the pressure in the autoclave is kept unchanged, the temperature is controlled at 50℃, and the catalytic reaction is carried out for 70min, after the reaction is completed, the temperature is lowered to 25℃, the H2 in the autoclave is replaced with N2 three times, sampling is performed into liquid chromatography for characterization, and the reaction results are as shown in Table 1.

[0101] Table 1 reaction results

[0102]

[0103]

[0104] According to Table 1, it can be seen that the selective debenzylation catalyst of the present application is basically completely converted in the catalytic hydrogenolysis debenzylation reaction of 4-chloro-N,N-dibenzyl aniline, indicating that the catalyst of the present application has high catalytic activity.

[0105] In the preparation method of the present application, when the stabilization time is 2-8h, and the mass percentage of hydrochloric acid solution and nitric acid solution is both 10%, the catalyst prepared in this way has the highest selectivity of product 4-chloro-aniline in the reaction, which can be as high as 99%, which may be due to the reaction modification of mixed acid to the carrier activated carbon affecting the structure and performance of the catalyst.

[0106] The above is only a preferred embodiment of the present application, and does not limit the present application in any way, and any simple modification, change and equivalent structural change made to the above embodiment according to the technical essence of the present application are still within the protection scope of the technical solution of the present application.

Claims

1. The application of a catalyst in the catalytic debenzylation reaction of 4-chloro-N,N-dibenzylaniline, characterized in that, The method for preparing the catalyst includes: Step 1: Wash the activated carbon with deionized water until neutral, filter, and dry until the water content is <1wt% to obtain the treated activated carbon; Step 2: Mix hydrochloric acid solution and nitric acid solution to obtain a mixed acid solution; the mass of the nitric acid solution is 4 times the mass of the hydrochloric acid solution, the mass percentage of the hydrochloric acid solution is 10%, and the mass percentage of the nitric acid solution is 10%. Step 3: Dissolve the palladium source in the mixed acid solution described in Step 2 to obtain a mixed acid solution containing the active component; Step 4: Place the activated carbon treated in Step 1 into the mixed acid solution containing the active components described in Step 3, and stir until it is evenly dispersed; Step 5: Continue stirring the dispersed system from Step 4 for 2-8 hours to stabilize it, filter it to obtain the stabilized material, and dry the stabilized material until the water content is <1wt% to obtain the selective debenzylating catalyst.

2. The application of the catalyst according to claim 1 in the catalytic debenzylation reaction of 4-chloro-N,N-dibenzylaniline, characterized in that, In step one, the activated carbon has a particle size of 200-400 mesh and a specific surface area >1000 m². 2 / g.

3. The application of the catalyst according to claim 1 in the catalytic debenzylation reaction of 4-chloro-N,N-dibenzylaniline, characterized in that, In step three, the palladium source includes palladium chloride, palladium nitrate, or potassium palladium chloride; in step three, the mass of the mixed acid solution is 80 to 200 times the mass of palladium.

4. The application of the catalyst according to claim 1 in the catalytic debenzylation reaction of 4-chloro-N,N-dibenzylaniline, characterized in that, In step four, the mass of the mixed acid solution containing the active components is 4 to 10.5 times the mass of the treated activated carbon.

5. The application of the catalyst according to claim 4 in the catalytic debenzylation reaction of 4-chloro-N,N-dibenzylaniline, characterized in that, The mass of the mixed acid solution is 5 to 8 times the mass of the treated activated carbon.

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