阅读说明：本技术 一种α-羰基磺酸酯的合成方法及其使用的催化剂 (Synthetic method of alpha-carbonyl sulfonate and catalyst used by same ) 是由 杨勇 宋涛 张银潘 于 2021-01-07 设计创作，主要内容包括：本发明提供一种用于合成α-羰基磺酸酯的氮和碳共掺杂的Nb-2O-5催化剂,其制备方法,以及使用所述催化剂在可见光驱动下合成α-羰基磺酸酯中的方法。其中,基于催化剂的总重量,所述氮的含量0.01wt％～1wt％；所述碳的含量为0.01wt％～1.5wt％。本发明所述的催化剂用于烯烃需氧氧化制备α-羰基磺酸酯,反应条件温和,氧气作为氧化剂,不需要使用其它氧化剂。所述催化剂的所有原料资源丰富,价格低廉,且催化剂可循环使用不失活,对空气、水和热都很稳定。(The invention provides nitrogen and carbon co-doped Nb for synthesizing alpha-carbonyl sulfonate 2 O 5 Catalysts, methods of making the same, and methods of using the catalysts in the synthesis of alpha-carbonyl sulfonates driven by visible light. Wherein, based on the total weight of the catalyst, the content of the nitrogen is 0.01wt percent to 1wt percent; the content of the carbon is 0.01 wt% -1.5 wt%. The catalyst of the invention is used for preparing alpha-carbonyl sulfonate by aerobic oxidation of olefin, the reaction condition is mild, oxygen is used as an oxidant, and other oxidants are not needed. All raw material resources of the catalyst are rich, the cost is low, and the catalyst can be recycled without inactivation and is stable to air, water and heat.)

1. Nitrogen and carbon co-doped Nb for synthesizing alpha-carbonyl sulfonate₂O₅A catalyst, wherein the nitrogen content is from 0.01 wt% to 1 wt%, preferably from 0.02 wt% to 0.8 wt%, more preferably from 0.03 wt% to 0.65 wt%, based on the total weight of the catalyst; the content of the carbon is 0.01 wt% to 1.5 wt%, preferably 0.01 wt% to 1 wt%, and more preferably 0.015 wt% to 0.85 wt%.

2. A method of preparing the catalyst of claim 1, comprising the steps of:

1) mixing a precursor containing carbon and nitrogen and a precursor containing niobium in a mixed solvent of water and alcohol, wherein the molar ratio of nitrogen to niobium is 1: 1-6, preferably 1: 2-4, most preferably 1: 3; the molar ratio of nitrogen to carbon is 1: 0.25 to 4, preferably 1: 0.3 to 3; the weight ratio of the mixed solvent to the precursor containing niobium is 10-50: 1, preferably 15 to 40: 1

2) Putting the product obtained in the step 1) into a sealed hydrothermal reaction kettle for hydrothermal process;

3) the product obtained in step 2) is calcined at a temperature of 200-600 ℃, more preferably 250-550 ℃ after separation, washing and drying.

3. The method of claim 2, wherein,

in the step 1) of the process,

the precursor containing carbon and nitrogen is a mixture of a precursor containing carbon and a precursor containing nitrogen respectively or a precursor containing carbon and nitrogen simultaneously; more preferably one or more selected from the group consisting of 2-methylimidazole, urea, melamine and ethanolamine;

preferably, the precursor containing niobium is a niobium salt, more preferably one or more selected from niobium oxalate and niobium chloride;

preferably, the volume ratio of water to alcohol in the mixed solvent in step 1) is 1: 0.1 to 10; more preferably 1: 1-6;

preferably, the alcohol is an aliphatic alcohol having 1 to 6 carbon atoms, more preferably ethanol or propanol;

preferably, the mixing in step 1) is carried out at a temperature of from 20 ℃ to 70 ℃, more preferably from 40 ℃ to 70 ℃.

4. The method of claim 2, wherein,

in the step 2) of the process,

the temperature of the hydrothermal process is 120-250 ℃, more preferably 160-200 ℃, and most preferably 180 ℃;

preferably, the hydrothermal process is carried out for a period of time of 12 to 36 hours, preferably 18 to 28 hours.

5. The method of claim 2, wherein,

in the step 3) of the process,

the calcination time is 1-5 hours, preferably 1.5-3 hours;

preferably, the heating rate is 2 ℃/min to 10 ℃/min;

preferably, the separation is carried out by centrifugation, preferably at 3000-7000 rpm for 5-15 minutes;

preferably, the washing is repeated 3 times using ethanol and the drying is carried out in vacuo at 60 ℃ for 12 hours.

6. A method of preparing an alpha-carbonyl sulfonate, comprising the steps of:

dispersing an olefin with a sulfinate in a solvent under an oxygen atmosphere in a nitrogen and carbon co-doped Nb for synthesizing an alpha-carbonyl sulfonate according to claim 1₂O₅Catalyst or nitrogen and carbon co-doped Nb for synthesizing alpha-carbonyl sulfonates prepared according to the method of any one of claims 2 to 5₂O₅In the presence of a catalyst, alpha-carbonyl sulfonate is obtained by reaction under the condition of illumination.

7. The method for producing alpha-carbonyl sulfonate according to claim 6, wherein,

the olefin is an aromatic terminal olefin, an aliphatic terminal olefin or an internal olefin, more preferably styrene which is unsubstituted or substituted with hydrogen on the benzene ring;

preferably, the sulfinate is a substituted or unsubstituted arylsulfinate, more preferably a substituted or unsubstituted phenylsulfinate; even more preferably an alkali metal salt of substituted or unsubstituted benzenesulfinic acid or an alkaline earth metal salt of substituted or unsubstituted benzenesulfinic acid;

preferably, the molar ratio of olefin to arylsulfinate salt is 1: 2-6;

preferably, the mass ratio of the catalyst to the olefin is 0.5-3: 1.

8. the method for producing alpha-carbonyl sulfonate according to claim 7, wherein,

the substituent in the substituted aryl sulfinate is selected from C_1～10One or more of alkyl, halogen, ester group, cyano and trifluoromethyl;

the substituent of styrene in which the hydrogen on the benzene ring is substituted is selected from C_1～10One or more of alkyl, halogen, ester group, cyano and trifluoromethyl.

9. The method for producing alpha-carbonyl sulfonate according to claim 6 or 7, wherein,

the solvent is one or more selected from acetonitrile, tetrahydrofuran, dichloromethane and trifluorotoluene, and is preferably trifluorotoluene;

preferably, the concentration of the olefin is 0.01-1 mol/L, more preferably 0.01-0.5 mol/L;

preferably, the illumination condition is that the used light source is an LED blue light lamp with the power of 5-30W, and more preferably 5-10W;

preferably, the reaction time is 12 to 48 hours, more preferably 18 to 36 hours.

10. The nitrogen and carbon co-doped Nb for the synthesis of alpha-carbonyl sulfonate according to claim 1₂O₅Catalyst or nitrogen and carbon co-doped Nb for synthesizing alpha-carbonyl sulfonates prepared according to the method of any one of claims 2 to 5₂O₅Use of a catalyst for the preparation of an alpha-carbonyl sulfonate.

Technical Field

The invention belongs to green synthesis of fine chemicals, and particularly relates to nitrogen and carbon co-doped Nb₂O₅A catalyst, a preparation method thereof and a method for synthesizing alpha-carbonyl sulfonate ester under the drive of visible light by using the catalyst. The method adopts green oxygen as an oxidant, and realizes the high-efficiency synthesis of the alpha-carbonyl sulfonate under the mild condition by using visible light drive.

Background

The alpha-carbonyl sulfonate is an important organic synthesis intermediate and is widely applied to the preparation of important medical active intermediates. The development of the preparation method is relatively delayed compared to its wide application. So far, the reaction is basically carried out under severe conditions by using peroxides, hypervalent iodine compounds or persulfides as oxidizing agents and using substrates such as alkynes and ketones. But also has the disadvantages of low activity, poor selectivity, limited substrate application range and the like. Therefore, the development of a catalyst and a catalytic system with mild conditions and wide substrate applicability has important research significance and practical value.

Sulfonates (OTs) are widely used as an important synthetic building block in organic synthesis. The conversion and modification of the α -carbonyl sulfonate backbone is also benefited by the good reactivity and applicability of OTs.

By virtue of good reactivity and important application value of the alpha-carbonyl sulfonate, the alpha-carbonyl sulfonate is widely applied to heterocyclic ring preparation reaction containing nitrogen, oxygen, sulfur and other impurities.

Although alpha-carbonyl sulfonates have important application values in the field of organic synthesis and application methods and strategies have been developed further in recent years. However, the development of the production method is relatively delayed with respect to the search for the application. The current preparation method is usually carried out under relatively severe conditions by using strong oxidants such as peroxide, high-valence iodine compounds, and persulfide and taking alkyne or ketone as a substrate. The use of oxygen as an oxidant is the most desirable oxidation strategy, both for basic research and industrial applications. Based on the important application value of alpha-carbonyl sulfonate and the defects of the existing preparation method, the bifunctional Nb with Lewis property and oxidability is developed₂O₅The catalyst is applied to the reaction of preparing alpha-carbonyl sulfonate by aerobic oxidation of olefin, and has important research value for the preparation of the important synthetic building block and the development of the bifunctional catalyst.

Disclosure of Invention

In view of the problems in the prior art, the present invention aims to develop a catalyst for synthesizing alpha-carbonyl sulfonate, which has the advantages of simple preparation process, cheap and easily available raw materials, green catalytic process and environmental protection.

It is another object of the present invention to provide a process for preparing the catalyst according to the present invention.

It is still another object of the present invention to provide a method for preparing alpha-carbonyl sulfonate using the catalyst according to the present invention.

It is a further object of the present invention to provide the use of the catalyst according to the present invention for the preparation of alpha-carbonyl sulfonates.

According to a first aspect of the present invention, there is provided a nitrogen and carbon co-doped Nb for the synthesis of alpha-carbonyl sulfonates₂O₅A catalyst, wherein the nitrogen content is from 0.01 wt% to 1 wt%, preferably from 0.02 wt% to 0.8 wt%, more preferably from 0.03 wt% to 0.65 wt%, based on the total weight of the catalyst; the content of the carbon is 0.01 wt% to 1.5 wt%, preferably 0.01 wt% to 1 wt%, and more preferably 0.015 wt% to 0.85 wt%.

According to a second aspect of the present invention, there is provided a method for preparing the catalyst, comprising the steps of:

1) mixing a precursor containing carbon and nitrogen and a precursor containing niobium in a mixed solvent of water and alcohol, wherein the molar ratio of nitrogen to niobium is 1: 1-6, preferably 1: 2-4, most preferably 1: 3; the molar ratio of nitrogen to carbon is 1: 0.25 to 4, preferably 1: 0.3 to 3; wherein the weight ratio of the mixed solvent to the precursor containing niobium is 10-50: 1, preferably 15 to 40: 1

2) Putting the product obtained in the step 1) into a sealed hydrothermal reaction kettle for hydrothermal process;

3) the product obtained in step 2) is calcined at a temperature of 200-600 ℃, more preferably 250-550 ℃ after separation, washing and drying.

In the step 1) of the process,

preferably, the precursor containing carbon and nitrogen is a mixture of a precursor containing carbon and a precursor containing nitrogen respectively or a precursor containing carbon and nitrogen simultaneously; more preferably one or more selected from the group consisting of 2-methylimidazole, urea, melamine and ethanolamine.

Preferably, the niobium-containing precursor is a niobium salt, more preferably one or more selected from niobium oxalate and niobium chloride.

Preferably, the volume ratio of water to alcohol in the mixed solvent in step 1) is 1: 0.1 to 10; more preferably 1: 1 to 6.

Preferably, the alcohol is an aliphatic alcohol having 1 to 6 carbon atoms, more preferably ethanol or propanol.

Preferably, the mixing in step 1) is carried out at a temperature of from 20 ℃ to 70 ℃, more preferably from 40 ℃ to 70 ℃.

In the step 2) of the process,

preferably, the temperature of the hydrothermal process is from 120 ℃ to 250 ℃, more preferably from 160 ℃ to 200 ℃, and most preferably 180 ℃.

Preferably, the hydrothermal process is carried out for a period of time of 12 to 36 hours, preferably 18 to 28 hours.

In the step 3) of the process,

preferably, the calcination time is 1 to 5 hours, preferably 1.5 to 3 hours.

Preferably, the rate of temperature rise is 2 ℃/min to 10 ℃/min, preferably 5 ℃/min.

Preferably, the separation is performed by centrifugation, preferably at 3000-7000 rpm for 5-15 minutes, preferably 5000rpm for 10 minutes.

Preferably, the washing is repeated 3 times using ethanol and the drying is carried out in vacuo at 60 ℃ for 12 hours.

According to a third aspect of the present invention, there is provided a process for preparing an α -carbonyl sulfonate, comprising the steps of:

dispersing olefin and sulfinate in solvent under oxygen atmosphere in nitrogen and carbon co-doped Nb according to the invention₂O₅In the presence of a catalyst, alpha-carbonyl sulfonate is obtained by reaction under the condition of illumination.

Preferably, the olefin is an aromatic terminal olefin, an aliphatic terminal olefin or an internal olefin, more preferably styrene which is unsubstituted or substituted with hydrogen on the benzene ring.

Preferably, the sulfinate is a substituted or unsubstituted arylsulfinate, more preferably a substituted or unsubstituted phenylsulfinate; even more preferably an alkali metal salt of a substituted or unsubstituted benzenesulfinic acid or an alkaline earth metal salt of a substituted or unsubstituted benzenesulfinic acid.

Preferably, the molar ratio of olefin to arylsulfinate salt is 1: 2 to 6.

Preferably, the mass ratio of the catalyst to the olefin is 0.5-3: 1.

preferably, the substituents in the substituted arylsulfinate salt are selected from C_1～10One or more of alkyl, halogen, ester group, cyano and trifluoromethyl.

Preferably, the substituent of styrene in which the hydrogen on the benzene ring is substituted is selected from C_1～10One or more of alkyl, halogen, ester group, cyano and trifluoromethyl.

Preferably, the solvent is one or more selected from acetonitrile, tetrahydrofuran, dichloromethane and trifluorotoluene, preferably trifluorotoluene.

Preferably, the concentration of the olefin is 0.01-1 mol/L, and more preferably 0.01-0.5 mol/L.

Preferably, the illumination condition is that the used light source is an LED blue light lamp with the power of 5-30W, and more preferably 5-10W.

Preferably, the reaction time is 12 to 48 hours, more preferably 18 to 36 hours.

According to a fourth aspect of the present invention there is provided the use of a catalyst according to the present invention in the preparation of an alpha-carbonyl sulfonate.

The invention has the advantages that:

1. the preparation process of the catalyst is simple, and the raw materials are cheap and easy to obtain;

2. the catalytic process is green and environment-friendly;

3. oxygen is the only oxidant;

4. the substrate has wide application range;

5. the obtained product has important application in the preparation of medicine and material intermediates.

Drawings

Fig. 1 is a graph showing the results of the uv-vis diffuse reflection test of the catalysts obtained in preparation examples 1 to 4 according to the present invention and comparative preparation example 1.

FIG. 2 is the results of steady-state fluorescence lifetime tests of the catalysts obtained in preparation examples 1 to 4 according to the present invention and comparative preparation example 1.

Fig. 3 is a XRD test result of the catalysts obtained in preparation examples 1 to 4 according to the present invention and comparative preparation example 1.

Fig. 4 is a nuclear magnetic hydrogen spectrum of the catalyst obtained in preparation example 2 according to the present invention.

FIG. 5 is a nuclear magnetic carbon spectrum of the catalyst obtained in preparation example 2 according to the present invention.

Detailed Description

The present invention will be described in detail with reference to specific examples. Before the description is made, it should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.

The invention codope Nb with nitrogen and carbon₂O₅The semiconductor material is used as a catalyst for preparing alpha-carbonyl sulfonate through aerobic oxidation of olefin, the reaction conditions are mild, oxygen is used as an oxidant, and other oxidants are not required. All raw material resources of the catalyst are rich, the cost is low, and the catalyst can be recycled without inactivation and is stable to air, water and heat. According to the photocatalyst and the catalytic system, the yield of alpha-carbonyl sulfonate prepared by aerobic oxidation of olefin is over 60 percent.

Characterization of the instrument used:

1) ultraviolet-visible diffuse reflectance spectrometer: model PerkinElmer Lambda 365UV-vis, PerkinElmer Inc.

2) A steady-state fluorescence spectrometer: the model is Hitachi F-4600 spectrophotometer, and the manufacturer is Hitachi.

3) An element analyzer: model number Vario-EL-cube, manufacturer Elementary

4) XRD powder diffractometer: model number Bruker D8 Advance diffractometer, manufactured by Bruker.

5) Nuclear magnetic resonance spectrometer: model DRX-400 manufacturer Bruker.

Preparation of example 1

Nitrogen and carbon codoped Nb₂O₅And (3) preparing a catalyst.

0.0345g of 2-methylimidazole (0.00042mol) was used as the carbon source and the nitrogen source, 1.02g of niobium oxalate (0.0019mol) was used as the starting material, and physical mixing was performed at 60 ℃ using a mixed solution of water and ethanol at a volume mixing ratio of 0.3/1 (total volume 20 mL). The temperature of the hydrothermal process is 180 ℃, and the hydrothermal time is 24 hours. And centrifuging, washing, drying and calcining. The temperature was raised from room temperature at a rate of 5 ℃/min and the high temperature calcination temperature was 250 ℃ and calcination was continued at that temperature for 2 hours. Taking out the sample after the temperature of the tube furnace is reduced to the room temperature to obtain the nitrogen and carbon co-doped Nb₂O₅A catalyst. The resulting catalyst had a nitrogen content of 0.624 wt.% and a carbon content of 0.793 wt.% as determined by elemental analysis.

Preparation examples 2 to 4

The catalyst was prepared by the same procedure as in preparation example 1 except that the calcination temperature was as shown in table 1 below, and the results are shown in table 1.

Comparative preparation examples 1 to 2

The catalyst was prepared by the same procedure as in preparation example 1 except that the amount of 2-methylimidazole used as a carbon source and a nitrogenogen and the sintering temperature were as shown in table 2, and the results are shown in table 2. The nitrogen and carbon doping levels are shown in table 2 below.

TABLE 1

	Calcination temperature/. degree.C	Catalyst and process for preparing same	Nitrogen content/wt%	Carbon content/wt%
					Preparation of example 1	250	NC-Nb2O5-250	0.624	0.793
Preparation of example 2	350	NC-Nb2O5-350	0.112	0.582
					Preparation of example 3	450	NC-Nb2O5450	0.093	0.404
Preparation of example 4	550	NC-Nb2O5-550	0.034	0.015

TABLE 2

Testing

The catalysts prepared in preparation examples 1 to 4 and comparative preparation example 1 were passed through the ultraviolet-visible light diffuse reflection test, and the results are shown in fig. 1. As can be seen from fig. 1, the catalysts prepared according to preparation examples 1 to 4 have significant absorption in the visible light region.

The catalysts prepared according to preparation examples 1 to 4 and comparative preparation example 1 were subjected to the steady-state fluorescence spectrum test, and the results are shown in fig. 2. As can be seen from fig. 2, the nitrogen and carbon doping in the catalysts prepared according to preparation examples 1 to 4 of the present invention effectively suppresses electron recombination, thereby improving reaction efficiency.

In addition, an XRD spectrum, a nuclear magnetic hydrogen spectrum, and a nuclear magnetic carbon spectrum of the catalyst obtained in preparation example 2 according to the present invention are shown in fig. 4 and 5, respectively.

Comparative examples 1 to 2

Under the condition of closed reaction, adding 0.2mmol of styrene and 0.6mmol of sodium p-toluenesulfinate, using 20mg of the catalyst obtained in comparative preparation examples 1 to 2 and 2mL of trifluorotoluene, reacting at room temperature for 24 hours under the irradiation of 5w of blue light LED light in an oxygen atmosphere at normal pressure, filtering the reaction solution, and carrying out silica gel column chromatography to obtain the 2-oxo-2-phenylethyl 4-methylbenzenesulfonate structure which is determined by NMR nuclear magnetic test. The reaction results are shown in table 3.

Examples 1 to 5

Under the condition of closed reaction, adding 0.2mmol of styrene and 0.6mmol of sodium p-toluenesulfinate, respectively using 20mg of the catalyst obtained in preparation examples 1 to 4 and 2mL of trifluorotoluene, reacting at room temperature for 24 hours under the irradiation of 5w of blue light LED light in an oxygen atmosphere at normal pressure, filtering the reaction solution, and carrying out silica gel column chromatography to obtain 2-oxo-2-phenylethyl 4-methylbenzenesulfonate, wherein the structure is determined by NMR nuclear magnetic test. The specific reaction conditions are as follows:

TABLE 3

	Catalyst and process for preparing same	Nitrogen content/%)	Carbon content/%)	Yield/%)
					Comparative example 1	Nb2O5-CE1	0	0	11
Comparative example 2	Nb2O5-CE2	1.081	1.531	13
					Example 1	NC-Nb2O5-250	0.624	0.793	77
Example 2	NC-Nb2O5-350	0.112	0.582	83
					Example 3	NC-Nb2O5-450	0.093	0.404	63
Example 4	NC-Nb2O5-550	0.034	0.015	60

Examples 5 to 12

The operation and the steps are the same as those of the example 1, the types of the olefin and the sodium sulfinate (namely the substrate) are changed, the corresponding alpha-carbonyl sulfonate compounds (products) are obtained, the conversion rate is more than 99%, and the yield is different from 60% to 90%, and the specific results are shown in table 4:

TABLE 4

Example 13

Catalyst circulation

The method takes styrene and sodium p-toluenesulfinate for reaction to prepare 2-oxo-2-phenylethyl 4-methylbenzenesulfonate as a template reaction for carrying out a catalyst circulation experiment, and comprises the following steps:

under a sealed reaction condition, 0.2mmol of styrene, 0.6mmol of sodium p-toluenesulfinate, 20mg of the catalyst obtained in preparation example 2, and 2mL of trifluorotoluene were added, and the mixture was reacted at room temperature for 24 hours under irradiation of 5W blue LED light in an oxygen atmosphere, and the reaction solution was filtered and subjected to gas chromatography. The reaction solution was centrifuged (10000rpm, 15min), the supernatant was removed, 5mL of ethanol was added, the supernatant was removed by centrifugation, the above operation was repeated 3 times, and the resulting solid was dried in a vacuum oven at 40 ℃ for 12h for the next round of catalyst recycling. The catalyst according to the invention was confirmed in a recycle experiment to maintain a conversion of > 99% and a product selectivity of > 99% after 4 reuses.

The following examples are given by way of illustration of embodiments of the invention and are not to be construed as limiting the invention, and it will be understood by those skilled in the art that modifications may be made without departing from the spirit and scope of the invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.