Method for cyanation of carbon-sulfur bond in sulfur-containing compound

Abstract

The invention provides a method for cyanation of a carbon-sulfur bond in a sulfur-containing compound. The method comprises the following steps: adding a sulfur-containing compound, an ammonia source and a nitrogen-doped mesoporous carbon-loaded iron-based monatomic catalyst into a solvent, putting into a pressure container, sealing, introducing oxygen source gas of 0.2-2.0 MPa, and reacting at 100-180 DEG C for 6-30 hours, so as to oxidize and break a carbon-sulfur bond into the corresponding nitrile compound. The system has the advantages that the catalyst activity is high, the method is wide in application range, reaction conditions are easy to control, the catalyst can be recycled, post-treatment is simple and the like, and the system has a good application prospect.

Description

Technical Field

[0001] The invention relates to the field of chemistry and chemical engineering, and in particular to a method for cyanation of carbon-sulfur bonds in sulfur-containing compounds. Background Art

[0002] Cyano compounds, also known as organic nitriles, are an important component of pharmaceuticals, pesticides and fine chemicals. In 2010, more than 30 cyano organic compounds were identified with different medicinal indications, and more than 20 nitrile compounds are available for clinical development. In organic chemistry, nitriles can be used as important intermediates for the production of a large number of heterocycles, and can also be used to synthesize amines, amides, aldehydes and different carboxylic acid derivatives.

[0003] The traditional synthesis methods of nitrile compounds are: 1) nucleophilic substitution of alkyl and aryl halides and the classic Sandmeyer reaction, but usually require the use of highly toxic hydrocyanic acid or metal cyanide. 2) dehydration of amides or aldoximes, elimination of oxime ethers or oxime esters and oxidation of primary amines to corresponding nitriles. 3) preparation of aromatic nitriles using aromatic amines as raw materials; 4) preparation of aromatic nitriles using methyl aromatics as raw materials. However, from the perspective of green chemistry, the use of toxic solvents and expensive reagents, cumbersome operations and the generation of a large amount of inorganic waste limit their widespread application. In view of this, it is very urgent to develop a green, efficient, non-toxic and pollution-free catalytic system for direct ammoxidation of cheap and readily available alcohols to prepare nitriles, which has attracted widespread attention from researchers.

[0004] Therefore, it is worthwhile to develop a new highly active heterogeneous catalyst system for realizing efficient synthesis of organic nitriles. The present invention aims to develop a method for preparing nitrile compounds by catalyzing the oxidative cleavage of the carbon-sulfur bond of sulfur-containing compounds, which can realize the synthesis of aromatic, heterocyclic and aliphatic esters, and can be recycled for multiple times, and has industrial application prospects. Summary of the invention

[0005] The invention provides a novel preparation method of benzonitrile. The method uses a sulfur-containing compound as a substrate, oxygen as an oxygen source and ammonia as an ammonia source. Under the action of a catalyst, the sulfur-containing compound undergoes oxidative cracking to generate a nitrile compound. The substrate has wide applicability and the catalyst can be recycled.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing nitrile compounds by oxidatively breaking carbon-sulfur bonds of sulfur-containing compounds: adding the sulfur-containing compound, an iron-based single-atom catalyst supported by nitrogen-doped mesoporous carbon, an amine inorganic substance and a solvent into a 5 mL reaction bottle, and sealing the bottle with a polytetrafluoroethylene stopper with holes; transferring the bottle to a stainless steel high-pressure reactor, flushing with oxygen, emptying the bottle, and repeating the process for three times, then filling with 0.1-2 MPa of oxygen and 0.1-1 MPa of ammonia; placing the reactor in an oil bath at 130-150° C. for reaction for 6-30 hours, so that the carbon-sulfur bonds can be oxidatively broken to form corresponding nitrile compounds.

[0008] 1. In the above technical scheme, the preparation method of the nitrogen-doped mesoporous carbon-supported iron-based single-atom catalyst is as follows: weigh a certain amount of silica sol, add it to N,N-dimethylformamide (DMF), stir at room temperature, and mix by ultrasound to obtain a mixed solution A; weigh a certain amount of iron phthalocyanine (II), add it to solution A, stir at room temperature, and mix by ultrasound to obtain a mixed solution B, stir solution B at 170-200°C (specifically 180°C here), evaporate the solvent, obtain a dry solid, and then calcine it at 900°C in a nitrogen atmosphere for 2 hours (heating rate is 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in a 18% by mass HF solution for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C for 12 hours to obtain the target catalyst Fe-NC; wherein the Fe mass content is 0.1-2wt%, and the N mass content is 1-5wt%.

[0009] 2. In the above technical scheme, the sulfur-containing compound molecules include aromatic, heterocyclic and aliphatic. For the aromatic compounds, other substituents on the benzene ring are one or more of -CH3, -OCH3, -C(CH3)3, -F, -Cl, -Br, -CF3; for the sulfur-containing compounds with other substituents on the benzene ring, the positions of the other substituents are ortho, meta or para; for the sulfur-containing compounds with other substituents on the benzene ring, the number of the other substituents is 1, 2, 3, 4 or 5; the heterocyclic compounds are one or more of naphthyl, furan ring, thiophene ring and pyridine ring; the aliphatic compounds do not contain branches and have 3-10 carbon atoms.

[0010] 3. In the above technical solution, the ammonia source used is an amine inorganic compound, including one or more of ammonia water, ammonium carbonate, ammonium bicarbonate, ammonium sulfate, ammonium acetate, and ammonium chloride.

[0011] 4. In the above technical solution, the molar ratio of the amount of catalyst added to the amount of sulfur compound reactant added is 0.01-0.05, preferably 0.05.

[0012] 5. In the above technical solution, the oxygen pressure used is 0.1-2MPa, preferably 0.5MPa, and the ammonia pressure used is 0.1-1MPa, preferably 0.5MPa.

[0013] 6. In the above technical solution, the reaction temperature used is 80-150°C, and the reaction time is 6-30h, preferably 150°C, 9h.

[0014] 7. In the above technical solution, the oxygen source used is one or both of pure oxygen and air.

[0015] 8. In the above technical scheme, the solvent used for the oxidation of sulfur-containing compounds is one or more of toluene, tert-amyl alcohol, 1,4-dioxane, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, n-heptane, methanol, and ethanol. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope (SEM) image of the nitrogen-doped mesoporous carbon-supported iron-based catalyst prepared as described below.

[0017] Figure 2 This is a transmission electron microscope (TEM) image of the nitrogen-doped mesoporous carbon-supported iron-based catalyst prepared as described below. DETAILED DESCRIPTION

[0018] The following examples will help to understand the present invention, but the present invention is not limited thereto.

[0019] The preparation method of the nitrogen-doped mesoporous carbon-supported iron-based single-atom catalyst used in the following examples is:

[0020] A certain amount of silica sol was weighed and added to N,N-dimethylformamide (DMF), stirred at room temperature and ultrasonicated until mixed uniformly to obtain a mixed solution A; a certain amount of iron phthalocyanine (II) was weighed and added to solution A, stirred at room temperature and ultrasonicated until mixed uniformly to obtain a mixed solution B, and solution B was stirred at 170-200°C (specifically 180°C in this case), the solvent was evaporated to obtain a dry solid, and then calcined at 900°C in a nitrogen atmosphere for 2 hours (heating rate of 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in a 18% by mass dilute HF solution for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C for 12 hours to obtain the target catalyst Fe-NC with a porous structure. The Fe content is 1wt%. Figure 1 , 2 , we can see the porous morphology of Fe-NC, and the pore size is about 2-50nm, which proves its mesoporous structure. Figure 2, it can be seen that Fe-NC does not exist in particle form, indicating that there is no iron oxide, proving that it is a single atom catalyst.

[0021] A certain amount of silica sol was weighed and added to N,N-dimethylformamide (DMF), stirred at room temperature and ultrasonicated until mixed uniformly to obtain a mixed solution A; a certain amount of iron phthalocyanine (II) was weighed and added to solution A, stirred at room temperature and ultrasonicated until mixed uniformly to obtain a mixed solution B, and solution B was stirred at 170-200°C (specifically 180°C in this case), the solvent was evaporated to obtain a dry solid, and then calcined at 900°C in a nitrogen atmosphere for 2 hours (heating rate of 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was dried in an oven at 80°C for 12 h to obtain the target catalyst Fe-NC (not acid-washed).

[0022] The preparation method of the nitrogen-doped mesoporous carbon-supported copper-based catalyst used in the following example is as follows: a certain amount of silica sol is weighed, added to N,N-dimethylformamide (DMF), stirred at room temperature, and ultrasonicated until mixed uniformly to obtain a mixed solution A; a certain amount of copper phthalocyanine (II) is weighed, added to solution A, stirred at room temperature, and ultrasonicated until mixed uniformly to obtain a mixed solution B, and the B solution is stirred at 170-200°C (specifically 180°C in this case), the solvent is evaporated, and a dry solid is obtained, which is then calcined at 900°C in a nitrogen atmosphere for 2 hours (the heating rate is 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in a 18% by mass HF solution for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C for 12 hours to obtain the target catalyst Cu-NC.

[0023] The preparation method of the nitrogen-doped mesoporous carbon-supported nickel-based catalyst used in the following example is as follows: a certain amount of silica sol is weighed, added to N,N-dimethylformamide (DMF), stirred at room temperature, and ultrasonicated until mixed to obtain a mixed solution A; a certain amount of nickel phthalocyanine (II) is weighed, added to solution A, stirred at room temperature, and ultrasonicated until mixed to obtain a mixed solution B, and solution B is stirred at 170-200°C (specifically 180°C in this case), the solvent is evaporated, and a dry solid is obtained, which is then calcined at 900°C in a nitrogen atmosphere for 2 hours (heating rate is 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in a dilute HF solution for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C for 12 hours to obtain the target catalyst Ni-NC.

[0024] The preparation method of the nitrogen-doped mesoporous carbon-supported non-metal catalyst used in the following example is as follows: a certain amount of silica sol is weighed, added to N,N-dimethylformamide (DMF), stirred at room temperature, and ultrasonicated until mixed to obtain a mixed solution A; a certain amount of phthalocyanine is weighed, added to solution A, stirred at room temperature, and ultrasonicated until mixed to obtain a mixed solution B, and solution B is stirred at 170-200°C, the solvent is evaporated, and a dry solid is obtained, which is then calcined at 900°C in a nitrogen atmosphere for 2 hours (heating rate is 5°C min -1 ), calcined and cooled to room temperature to obtain a black powder, which was soaked in a dilute HF solution for more than 24 hours, and finally washed with deionized water until neutral, and dried in an oven at 80°C for 12 hours to obtain the target catalyst NC.

[0025] Example 1

[0026] Fe-NC (in terms of iron, 5 mol% relative to the raw material), benzyl mercaptan (0.25 mmol) and 2 mL of acetonitrile were added to a 5 mL reaction bottle in sequence, and then transferred to a stainless steel high-pressure reactor, filled with ammonia pressure to 0.5 MPa, and oxygen pressure to 0.5 MPa. The reactor was placed in a 150° C. oil bath and stirred at 550 rpm for 9 h. After the reaction, the reactor was cooled to room temperature, opened, and internal standard naphthalene (20 mg) was added. The qualitative product was detected by gas chromatography-mass spectrometry. The quantitative conversion rate of the substrate benzyl mercaptan and the yield of the product benzonitrile by gas chromatography internal standard method are shown in Table 1.

[0027] Example 2-28

[0028] Except for the catalyst and dosage, pressure and reaction time, the catalyst activity evaluation is the same as that in Example 1. The reaction conditions and catalytic reaction results are shown in Table 1. It can be seen from Table 1 that the catalyst and dosage, oxygen pressure, ammonia pressure, reaction temperature and reaction time have an effect on the catalytic effect. With the increase of reaction temperature (Examples 1 and 2, 3), reaction time (Examples 1 and 4, 5), the yield increases, and the ratio and pressure of oxygen and ammonia (Examples 1 and 6-17), solvent type (Examples 1 and 18-24), the dosage and type of catalyst (Examples 1 and 25-31), the catalytic effect is also different.

[0029] Table 1 Preparation of organic nitrile by oxidative cleavage of benzyl mercaptan

[0030]

[0031]

[0032] The amount of catalyst refers to the mol% of the raw material in terms of iron (Cu, Ni); NC means it is the same as Fe-NC;

[0033] Examples 32-59

[0034] Except for the different substrates, the catalyst activity evaluation and reaction conditions were the same as those in Example 1, and the reaction time was 9-24 h. The substrates and catalytic reaction results are shown in Table 2. All sulfur-containing compound substrates can undergo oxidative cleavage to generate corresponding organic nitrile compounds, which indicates the universality of this method.

[0035] Table 2 Oxidative cleavage of sulfur-containing substrates

[0036]

[0037]

[0038]

[0039] The catalytic oxidation method of the present invention has high efficiency, strong specificity and high product yield; the oxidant is economical and environmentally friendly oxygen or air, and has high application value.

Claims

1. A method for cyanation of carbon-sulfur bonds in sulfur-containing compounds, characterized in that: A sulfur-containing compound and a nitrogen-doped mesoporous carbon-supported iron-based catalyst are added to a solvent, placed in a sealed pressure vessel, introduced with 0.1-2MPa oxygen source gas and 0.1-1MPa ammonia source gas, and reacted at 100-180°C for 6-30 hours to oxidatively break the carbon-sulfur bond into the corresponding nitrile compound.

2. The method according to claim 1, characterized in that The nitrogen-doped mesoporous carbon-supported catalyst is an iron-based single-atom catalyst supported by nitrogen-doped mesoporous carbon. The preparation method of the nitrogen-doped mesoporous carbon-supported copper-based single-atom catalyst is as follows: Weigh 1-3g silica sol (preferably 1.25-2g), add it to 40-60mL N,N-dimethylformamide (DMF) (preferably 45-55mL), stir at room temperature, and mix by ultrasound to obtain a mixed solution A; weigh 0.2-1g phthalocyanine iron (II) (preferably 0.4-0.6g), add it to solution A, stir at room temperature, and mix by ultrasound to obtain a mixed solution B, stir solution B at 170-200°C, evaporate the solvent, obtain a dry solid, and then calcine at 800-900°C in a nitrogen atmosphere for more than 2 hours (the heating rate from room temperature to 800-900°C is 3-10°C min -1 ), calcined and cooled to room temperature to obtain a black powder, soaked in 15-30% HF for more than 24 hours, finally washed with deionized water until neutral, and dried in an oven at 80-120°C to obtain the target catalyst Fe-NC; wherein the Fe mass content is 0.1-2wt%, and the N mass content is 1-5wt%.

3. The method according to claim 1, characterized in that: The molar ratio of the amount of catalyst (calculated as iron) added to the amount of sulfur-containing compound reactants charged is 0.02-0.2, preferably 0.05-0.

1.

4. The method according to claim 1, characterized in that: The solvent is one or more of toluene, tert-amyl alcohol, 1,4-dioxane, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile, n-heptane, methanol and ethanol.

5. The method according to claim 1, characterized in that The reaction temperature is 100-180°C, preferably 130-150°C; the oxygen pressure is 0.2-2.0MPa, preferably 0.5MPa; the ammonia pressure is 0.1-1Mpa, preferably 0.5MPa; and the reaction time is 6-30h, preferably 9-24h.

6. The method according to claim 1 or 2, characterized in that: The sulfur-containing compound is a C1-C20 alkyl mercaptan (or ether) or a benzyl mercaptan (or ether) compound. (Benzyl mercaptan: R2 = H; benzyl sulfide: R2 = one or more of C1-C20 alkyl, phenyl or phenyl with C1-C10 alkyl on the benzene ring, naphthyl, thiophene ring, pyridine ring), in the benzyl mercaptan (ether) compound molecule, the substituent R1 on the benzene ring is one or more of phenyl, naphthyl, thiophene ring, pyridine ring, -H, -CH3, -OCH3, -C(CH3)3, -F, -Cl, -Br, -CF3; or, the benzene ring can be replaced by a naphthalene ring, a thiophene ring or a pyridine ring; In the benzyl mercaptan (ether) compound having other substituents on the benzene ring, the position of the other substituent R1 is ortho, meta or para; In the benzyl mercaptan (ether) compound having other substituents on the benzyl ring, the number of the other substituents is 1, 2, 3, 4 or 5.

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