CN115555051B - A Pd/CuMOF-x composite catalyst, preparation method and application - Google Patents

Abstract

The invention discloses a Pd/CuMOF-x composite material catalyst, a preparation method and application thereof, wherein the chemical expression of the CuMOF is { [ Cu (L) (H) ₂ O)]} _n Wherein L is ^2‑ 4-pyridine methylene phosphonic acid radical is represented, and is a metal organic framework material containing Cu ions and taking 4-pyridine methylene phosphonic acid as a ligand; x represents the mass percent of Pd in the composite material and 0<x<10. The Pd/CuMOF-x composite material is a Pd/Cu bimetallic heterogeneous catalyst, can efficiently catalyze 3, 4-dichloronitrobenzene to synthesize diuron technical by a one-pot method in CO atmosphere, avoids the use of highly toxic phosgene, and has the advantages of short synthetic route, convenient post-treatment, low cost, high reaction yield, environmental friendliness and the like.

Description

A Pd/CuMOF-x composite catalyst, preparation method and application

Technical field

The invention relates to the field of pesticide synthesis catalysts, and specifically relates to a Pd/CuMOF-x composite material catalyst, a preparation method and its application.

Background technique

Diuron, whose chemical name is N-(3,4-dichlorophenyl)-N',N'-dimethylurea, is an asymmetrically substituted urea herbicide and is suitable for rice, cotton, and corn. , sugar cane, fruit, gum, mulberry, and tea gardens to control barnyard grass, crabgrass, setaria, polygonum, pigweed, and cabbage. Its structure is shown in the following formula (I):

At present, the synthesis methods of diuron mainly include the phosgene method (CN201210191499.X; CN201710421976.X) and the non-phosgene method. Among them, the phosgene method (also known as the isocyanate method) requires a three-step process of reduction, esterification, and water addition. It requires the use of several times an excess of the highly toxic gas phosgene. Therefore, the safety requirements of the production process are extremely high, and it also requires A large amount of highly corrosive chlorine-containing compounds will be produced, and the post-treatment process and equipment are complex. The non-phosgene method uses CO instead of the highly toxic phosgene as the carbonylation reagent, and directly synthesizes diuron (see the figure below) through the selective redox carbonylation method. It is more popular because of its fewer reaction steps, atom economy and environmental friendliness. attracting more and more attention.

For example, Zhang Xiaopeng et al. reported the "one-pot" synthesis of diuron by selenium-catalyzed redox carbonylation reaction (Chemical Bulletin, 2016, 79(12):1192-1195); Wang Yan in his master's thesis "Se-catalyzed carbonylation synthesis" There are similar reports in "Diuron, 4-pyridylurea and benzimidazol-2-yl carbamate". In addition, noble metal catalysts such as Rh, Ru and Pd can also catalyze redox carbonylation reactions to synthesize various substituted urea compounds (diuron analogs) (Journal of Molecular Catalysis, 1990 (1): L15-L18; Chemistry Progress, 2002, 14(6): 433-437.) The above-mentioned non-phosgene methods for synthesizing diuron have some shortcomings. For example, the method of synthesizing diuron through selenium-catalyzed carbonylation also needs to add the substrate 3,4-dichloronitrobenzene. Twice the molar amount of triethylamine was used as a cocatalyst, and the yield of diuron was not high enough. In the method of synthesizing substituted urea compounds using a single noble metal Pd(CH ₃ COO) ₂ catalytic reduction carbonylation reaction, it is also necessary to add PPh ₃ and cocatalyst NEt ₄ Cl.

The present invention uses CuMOF material with large specific surface area, adjustable pore size and good stability as a catalyst carrier, grafts the active center Pd onto the CuMOF carrier, and prepares a Pd/CuMOF-x composite catalyst, using Pd as the active center and Cu as the The synergistic effect of metals, under CO atmosphere, ensures the catalyst's high catalytic activity and higher reaction yield during the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron.

Contents of the invention

The present invention aims to provide a preparation method of a Pd/CuMOF-x composite catalyst for the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron, so as to solve the problem that the existing technology is not environmentally friendly and the existing catalysis The technical problem is that the yield of the target product of the system is not high enough.

In order to achieve the above objects, the technical solutions adopted by the present invention are as follows:

A Pd/CuMOF-x composite catalyst, which is used for the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron. The chemical expression of CuMOF is {[Cu(L)(H ₂ O)]}n, is a Cu ²⁺ -containing metal-organic framework material with 4-pyridylmethylenephosphonic acid as the ligand; L ^2- represents 4-pyridylmethylenephosphonate, and Pd is loaded on CuMOF. x represents the mass percentage of Pd in the composite catalyst, 0<x<10.

Each asymmetric unit of the CuMOF contains 1 deprotonated organic ligand L ^2- , 1 copper ion and 1 coordinated water molecule, and its molecular structure is as follows:

Preferably, the mass percentage of Pd in the composite material is 4.12%, and the prepared composite material is Pd/CuMOF-4.

A method for preparing a Pd/CuMOF-x composite catalyst for the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron. First, CuMOF (chemical expression is {[Cu(L)(H ₂ O)]} _n ) as a catalyst carrier, and then Pd is loaded on the CuMOF carrier to prepare a bimetallic Pd/CuMOF-x composite catalyst.

Preferably, the specific preparation steps of the Pd/CuMOF-x composite catalyst are as follows:

(1) Dissolve copper nitrate and 4-pyridylmethylenephosphonic acid in ultrapure water, mix them evenly by ultrasonic, and adjust the pH of the solution system to 4.0. Then transfer the mixture to a container with polytetrafluoroethylene The reaction is carried out in a lined high-pressure reactor in an oven. After natural cooling, filtering, washing, and drying, the CuMOF material is obtained.

(2) Dissolve the CuMOF material and Pd(II) salt prepared in step (1) in DMF, and mix them evenly by ultrasonic. The mixture was then transferred to a high-pressure reactor lined with polytetrafluoroethylene and reacted in an oven. After natural cooling, filtering, washing, and drying, the Pd/CuMOF-x composite material was obtained.

Further, the Pd(II) salt described in step (2) is selected from one of PdCl ₂ , Pd(OAc) ₂ , and Pd(TFA) ₂ .

Furthermore, in step (2), the reaction temperature in the oven is 120-160°C, and the reaction time is 36-72 hours.

Furthermore, in step (2), the mass percentage of Pd in the composite material is x%=1%~10%.

Compared with the prior art, the present invention has the following beneficial effects:

1. Bimetallic Pd/CuMOF-x composites with 4-pyridylmethylenephosphonate as ligand were prepared for the first time.

2. Through the synergistic catalytic effect of Pd and Cu in the Pd/CuMOF-x composite material, the reaction yield of the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron is effectively improved.

3. Use cheap and easily available CO to replace the highly toxic phosgene, and Pd/CuMOF-x composite materials to replace Se as the catalyst to directly synthesize the original drug of diuron, which has the advantages of short synthesis route, increased reaction yield, and environmental friendliness.

Description of the drawings

Figure 1 shows the X-ray diffraction pattern of Pd/CuMOF-4 composite material;

Figure 2 shows the infrared spectrum of Pd/CuMOF-4 composite material;

Figure 3 is the infrared spectrum of the diuron product prepared by the one-pot method;

Figure 4 is a high-resolution mass spectrum (ESI-HRMS) image of the diuron product prepared by the one-pot method.

Detailed ways

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with various embodiments and drawings. Implementation methods of the present invention include but are not limited to the following embodiments.

Example 1: Preparation of CuMOF

Add 0.483g Cu(NO ₃ ) ₂ ·3H ₂ O and 0.342g 4-pyridylmethylenephosphonic acid to 40 mL of deionized water respectively, then adjust the pH to 4.0 with 1.0 M NaOH, and transfer to a 100 mL high-pressure reaction kettle. , reacted in an oven at 110°C for 72h. After cooling to room temperature, it is washed with ultrapure water and absolute ethanol, and dried to obtain blue crystals, which are CuMOF. Grind the CuMOF material into small particles for later use.

Example 2: Preparation of Pd/CuMOF-2 composite catalyst

Dissolve the ground 0.0505g CuMOF material and 0.0035g PdCl ₂ in 10mL DMF and mix them evenly by ultrasonic. The mixture was then transferred to a 50 mL high-pressure reactor lined with polytetrafluoroethylene, and the sealed container was heated at 120°C for 36 h. After natural cooling, filter, and the solid obtained is washed thoroughly with ultrapure water and ethanol, and dried in a vacuum oven at 50-60°C for 24 hours. The blue-black crystals obtained are Pd/CuMOF-x composite materials with a loading ratio of 2.32%, recorded is Pd/CuMOF-2.

Example 3: Preparation of Pd/CuMOF-4 composite catalyst

Dissolve the ground 0.0505g CuMOF material and 0.0090g Pd(OAc) ₂ in 10mL DMF, and mix them evenly by ultrasonic. The mixture was then transferred to a 50 mL high-pressure reactor lined with polytetrafluoroethylene, and the sealed container was heated at 140°C for 48 h. After natural cooling, filter, and the solid obtained is washed thoroughly with ultrapure water and ethanol, and dried in a vacuum oven at 50-60°C for 24 hours. The blue-black crystals obtained are Pd/CuMOF-x composite materials with a loading ratio of 4.12%, recorded is Pd/CuMOF-4.

The X-ray diffraction pattern of the obtained Pd/CuMOF-4 is shown in Figure 1, and the infrared spectrum pattern is shown in Figure 2. The infrared spectrum data is IR (KBr, cm ^-1 ): 3016 (m), 2948 (m), 2915 (m), 1608 (s), 1419 (m), 1250 (m), 1216 (m), 1130 ( s), 1042(s), 992(s), 831(m), 561(s).

Example 4: Preparation of Pd/CuMOF-6 composite catalyst

Dissolve the ground 0.0505g CuMOF material and 0.0200g Pd(TFA) ₂ in 10mL DMF, and mix them evenly by ultrasonic. The mixture was then transferred to a 50 mL high-pressure reactor lined with polytetrafluoroethylene, and the sealed container was heated at 160°C for 72 h. After natural cooling, filter, and the solid obtained is washed thoroughly with ultrapure water and ethanol, and dried in a vacuum oven at 50-60°C for 24 hours. The blue-black crystals obtained are Pd/CuMOF-x composite materials with a loading ratio of 6.28%, recorded is Pd/CuMOF-6.

Example 5: Preparation of Pd/CuMOF-8 composite catalyst

Dissolve the ground 0.0505g CuMOF material and 0.0220g PdCl ₂ in 10mL DMF, and mix them evenly by ultrasonic. The mixture was then transferred to a 50 mL high-pressure reactor lined with polytetrafluoroethylene, and the sealed container was heated at 160°C for 72 h. After natural cooling, filter, and the solid obtained is washed thoroughly with ultrapure water and ethanol, and dried in a vacuum oven at 50-60°C for 24 hours. The blue-black crystals obtained are Pd/CuMOF-x composite materials with a loading ratio of 8.26%, recorded is Pd/CuMOF-8.

Related performance testing

The Pd/CuMOF-x composite catalyst prepared in Examples 1 to 4 was catalytically reduced and carbonylated to synthesize diuron in a CO atmosphere.

Example 6: Synthesis of diuron through catalytic reduction and carbonylation reaction of Pd/CuMOF-2 composite material

In a cold 100mL stainless steel reactor, add 3,4-dichloronitrobenzene (5mmol), dimethylamine hydrochloride (10mmol), Pd/CuMOF-2 catalyst (30mg) and THF (20mL) in sequence, and seal . Replace the air with 1.0MPa CO three times, and then raise the CO pressure in the reactor to 3.0MPa. Start the stirring device of the reaction kettle, and heat the reaction kettle to 180°C for 3 hours.

After the reaction is completed, the reaction kettle is cooled to room temperature and the residual gas is released. Open the reaction kettle, place it in the air and stir for another 1 hour. Then the filter residue is removed by suction filtration, and then the solvent is removed under reduced pressure. Finally, the target product diuron is obtained through column chromatography (eluent: petroleum ether/ethyl acetate volume ratio 6:1). Yield: 77.4%.

The melting point of the synthesized diuron was measured to be 157–158°C, and the literature value was 158–159°C (Zhu Liangtian. Handbook of Fine Chemical Products—Pesticide Volume. Beijing: Chemical Industry Press, 2004, 411-412).

The infrared spectrum (Figure 3) data is: IR (ν, cm ^-1 ): 3301, 2928, 1656, 1587, 863, 814, 755, 635, 574. Among them, 3301cm ^-1 is the NH bond stretching vibration absorption peak; 2928cm ^-1 is the methyl stretching vibration absorption Peak; 1656cm ^-1 is the carbonyl stretching vibration absorption peak; 1587cm ^-1 is the benzene ring skeleton vibration; 863cm ^-1 , 814cm ^-1 and 755cm ^-1 are the benzene ring substituted out-of-plane bending vibration and skeleton out-of-plane bending vibration absorption peaks; 635cm ^-1 and 574cm ^-1 are C-Cl bond stretching vibration absorption peaks.

High-resolution mass spectrometry (HRMS (ESI), Figure 4) data is: m/z[M+H] ⁺ The measured value is 233.0246, which is consistent with the theoretical value 233.0243 (calcd.forC ₉ H ₁₁ Cl ₂ N ₂ O).

Example 7: Synthesis of diuron through catalytic reduction and carbonylation reaction of Pd/CuMOF-4 composite material

In a cold 100mL stainless steel reactor, add 3,4-dichloronitrobenzene (5mmol), dimethylamine hydrochloride (10mmol), Pd/CuMOF-4 catalyst (30mg) and THF (20mL) in sequence, and seal . Replace the air with 1.0MPa CO three times, and then raise the CO pressure in the reactor to 3.0MPa. Start the stirring device of the reaction kettle, and heat the reaction kettle to 180°C for 3 hours.

After the reaction is completed, the reaction kettle is cooled to room temperature and the residual gas is released. Open the reaction kettle, place it in the air and stir for another 1 hour. Then the filter residue is removed by suction filtration, and then the solvent is removed under reduced pressure. Finally, the target product diuron is obtained through column chromatography (eluent: petroleum ether/ethyl acetate volume ratio 6:1). Yield: 84.5%.

The melting point, hydrogen nuclear magnetic spectrum, infrared, high-resolution mass spectrum and other data are the same as those in Example 6.

Example 8: Synthesis of diuron through catalytic reduction and carbonylation reaction of Pd/CuMOF-6 composite material

In a cold 100mL stainless steel reactor, add 3,4-dichloronitrobenzene (5mmol), dimethylamine hydrochloride (10mmol), Pd/CuMOF-6 catalyst (30mg) and THF (20mL) in sequence, and seal . Replace the air with 1.0MPa CO three times, and then raise the CO pressure in the reactor to 3.0MPa. Start the stirring device of the reaction kettle, and heat the reaction kettle to 180°C for 3 hours.

After the reaction is completed, the reaction kettle is cooled to room temperature and the residual gas is released. Open the reaction kettle, place it in the air and stir for another 1 hour. Then the filter residue is removed by suction filtration, and then the solvent is removed under reduced pressure. Finally, the target product diuron is obtained through column chromatography (eluent: petroleum ether/ethyl acetate volume ratio 6:1). Yield: 81.2%.

The melting point, hydrogen nuclear magnetic spectrum, infrared, high-resolution mass spectrum and other data are the same as those in Example 6.

Example 9: Synthesis of diuron through catalytic reduction and carbonylation reaction of Pd/CuMOF-8 composite material

In a cold 100mL stainless steel reactor, add 3,4-dichloronitrobenzene (5mmol), dimethylamine hydrochloride (10mmol), Pd/CuMOF-8 catalyst (30mg) and THF (20mL) in sequence, and seal . Replace the air with 1.0MPa CO three times, and then raise the CO pressure in the reactor to 3.0MPa. Start the stirring device of the reaction kettle, and heat the reaction kettle to 180°C for 3 hours.

After the reaction is completed, the reaction kettle is cooled to room temperature and the residual gas is released. Open the reaction kettle, place it in the air and stir for another 1 hour. Then the filter residue is removed by suction filtration, and then the solvent is removed under reduced pressure. Finally, the target product diuron is obtained through column chromatography (eluent: petroleum ether/ethyl acetate volume ratio 6:1). Yield: 80.6%.

The melting point, hydrogen nuclear magnetic spectrum, infrared, high-resolution mass spectrum and other data are the same as those in Example 6.

Taking the above-mentioned ideal embodiments of the present invention as inspiration and through the above description, relevant workers can make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the description, and must be determined based on the scope of the claims.

Claims (6)

1. The application of a Pd/CuMOF-x composite catalyst in the synthesis of diuron, which is characterized by: using 3,4-dichloronitrobenzene, dimethylamine and carbon monoxide as raw materials, and using Pd/CuMOF-x The composite material is used as a catalyst to synthesize diuron in one step; the composite catalyst is used for the reductive carbonylation of 3,4-dichloronitrobenzene to synthesize diuron. The chemical expression of CuMOF is {[Cu(L)(H ₂ O)]} _n , is a Cu ²⁺ -containing metal-organic framework material with 4-pyridylmethylenephosphonic acid as the ligand; L ^2- represents 4-pyridylmethylenephosphonate, and Pd is loaded on CuMOF , x represents the mass percentage of Pd in the composite catalyst, 0<x<10. 2. Application of the Pd/CuMOF-x composite catalyst in diuron synthesis according to claim 1, characterized in that: each asymmetric unit of the CuMOF contains 1 deprotonated organic ligand L ^2- , 1 copper ion and 1 coordinated water molecule, its molecular structure is as follows: . 3. Application of the Pd/CuMOF-x composite catalyst in diuron synthesis according to claim 1, characterized in that: the mass percentage of Pd in the composite material is 4.12%, and the prepared composite The material is Pd/CuMOF-4. 4. Application of the Pd/CuMOF-x composite catalyst in diuron synthesis according to claim 1, characterized in that the catalyst preparation steps are as follows: (1) Dissolve copper nitrate and 4-pyridylmethylenephosphonic acid in ultrapure water, mix them evenly by ultrasonic, adjust the pH of the solution system to 4.0, and then transfer the mixture to a polytetrafluoroethylene container. The reaction is carried out in a lined high-pressure reactor in an oven. After natural cooling, the CuMOF material is obtained by filtering, washing and drying; (2) Dissolve the CuMOF material and Pd(II) salt prepared in step (1) in DMF, mix them evenly by ultrasonic, and then transfer the mixture to a high-pressure reactor lined with polytetrafluoroethylene. , react in an oven, and after natural cooling, filter, wash, and dry to obtain Pd/CuMOF-x composite material. 5. The application of Pd/CuMOF-x composite catalyst in diuron synthesis according to claim 4, characterized in that: the Pd(II) salt is selected from PdCl ₂ , Pd(OAc) ₂ , Pd( TFA) ₂ . 6. The application of the Pd/CuMOF-x composite catalyst in the synthesis of diuron according to claim 4, characterized in that: in the step (2), the reaction temperature is 120 ~ 160 ° C, and the reaction time is 36~72 hours.