Preparation method of biomass-based 2, 5-dimethyl-N-substituted pyrrole derivative
Technical Field
The invention relates to a method for preparing a 2, 5-dimethyl-N-substituted pyrrole derivative by using renewable magnetic carbon-based sulfonic acid as a catalyst and biomass-based 2, 5-dimethylfuran as a raw material through ring opening to generate 2, 5-hexanedione and amine condensation dehydration reaction in sequence.
Background
Due to the increasing problems of resource shortage, environmental badness and the like, industrial production raw materials are gradually shifted from the traditional petrochemical resources to renewable biomass. Nitrogen-containing compounds are important organic compounds and play a significant role in medicine, pesticides, materials and dyes. At present, the synthesis method of the biomass-based nitrogen-containing compound mainly comprises the following 4 methods: (A) directly catalyzing and degrading natural nitrogenous biomass such as protein and chitin; (B) aldehyde/ketone reductive amination; (C) alcohol amination by hydrogen; (D) alkene/alkyne hydroamination reaction. These methods are effective in promoting the formation of C-N bonds, especially supported noble metals and homogeneous organometallic catalysts, which promote the production of higher yields of amides. In contrast, the non-noble metal has a large reserve and is cheap, and has application potential in the aspect of heterogeneous catalytic synthesis of biomass-based nitrogen-containing compounds, but the stability of the corresponding catalyst is poor, and side reactions such as over-alkylation and the like are difficult to avoid. Therefore, the design and preparation of the non-noble metal functional material which is easy to separate and recycle and is green have important research value for catalyzing the biomass raw material to be converted into the nitrogen-containing compound with high efficiency and high selectivity.
The pyrrole derivatives are important five-membered nitrogen heterocyclic compounds, and besides having excellent biological activity, the pyrrole derivatives are also widely applied to the fields of macromolecules, catalysts, dyes, foods and the like. Based on petrochemical products, the pyrrole derivative can be prepared by the reactions of Knorr, pal-Knorr, Barton-Zard, multi-component condensation, cycloaddition and the like. In recent years, domestic and foreign subject groups such as professor yao of science and technology university of china, professor jinguang of shanghai transportation university, George w.huber professor of madison university of wisconsin, professor Ning Yan of singapore national university, professor SanghoKoo of korea university of science and technology university of wisconsin, and the like, have reported that the pyrrole derivatives are synthesized by directly catalyzing biomass raw materials such as chitin, shrimp shells, bagasse and the like, but the obtained yield (20%) is not ideal and the reaction conditions are harsh (300 + 600 ℃). In addition, the biomass platform small molecules (furan, 2, 5-hexanedione and the like) are selected as raw materials in subject groups such as professor Cao Yong of compound denier university, professor Zhang Zeuze of Zhongnan university, professor Johannes G.de Vries of Germany Labrunitz catalysis research institute, and the like, so that high catalytic amination activity can be obtained under mild reaction conditions. Doulei et al, the research institute of science and technology of the university of Compound Dan, selects zeolite solid acid as a catalyst to catalyze the reaction of 2, 5-dimethylfuran and amine compounds. Although the yield of the obtained pyrrole is high, the used catalyst has the defects of high energy consumption, complicated operation process and the like.
Disclosure of Invention
The invention aims to: the method uses renewable biomass-based 2, 5-dimethylfuran and amine compounds as raw materials, and synthesizes the 2, 5-dimethyl-N-substituted pyrrole derivative by heating in an oil bath kettle so as to overcome the defects of higher cost of the existing catalyst or catalyst system, unsustainable reaction process and the like.
In order to achieve the purpose, the invention adopts the technical scheme that: dissolving 2, 5-dimethylfuran and amine compounds in an organic solvent, and reacting at a certain temperature and time to prepare the 2, 5-dimethyl-N-substituted pyrrole derivative. The principle of synthesizing the 2, 5-dimethyl-N-substituted pyrrole derivative is shown in the following figure: the 2, 5-dimethylfuran is subjected to ring opening under the action of heating and a magnetic acid catalyst to generate an intermediate of 2, 5-hexanedione, and then the intermediate and amine substances are subjected to amination, ring closing and dehydration to obtain a final product.
Wherein R is substituted phenyl, thiophene or furan; the substituent on the substituted phenyl is bromine, fluorine, nitro, hydroxyl or methoxy.
The preparation of the 2, 5-dimethyl-N-substituted pyrrole derivative is carried out in an oil bath kettle which is equipped with magnetic stirring, the oil bath kettle is opened, the specified reaction temperature is set, the reaction system is rapidly heated to the specified temperature through heat transfer, and the reaction temperature is kept constant by the temperature control of a thermocouple. The preparation process of the 2, 5-dimethyl-N-substituted pyrrole derivative comprises the following steps: putting 2, 5-dimethylfuran, an amine compound, a catalyst, distilled water and 2mL of solvent into a reaction kettle; and putting the assembled reaction kettle into an oil bath pan for heating. The reaction temperature is 110-170 ℃, the reaction time is 1-3h, and the consumption of distilled water is 0-250 mu L. After the reaction, the catalyst was separated from the reaction mixture system by a magnet.
The mass ratio of the 2, 5-dimethylfuran to the amine compound is 1: 1.
The amine compound is p-methoxyaniline, 3-fluoroaniline, 3-methoxyaniline, m-toluidine, o-toluidine, n-butylamine, 3-nitroaniline, 4-nitroaniline, p-trifluoromethylaniline, p-hydroxyphenylamine, n-hexylamine, furfurylamine, 2-thiophenemethylamine or benzylamine.
The organic solvent is absolute methanol, absolute ethanol, propanol, isopropanol, n-butanol, toluene, cyclohexane, dichloroethane or tetrahydrofuran.
Catalyst Fe of the invention3O4@SiO2@CS-SO3The amount of H is 5-20 wt%.
Compared with the prior art, the invention has the advantages that:
(1) the invention takes biomass-based 2, 5-dimethylfuran as a raw material, so that the whole reaction is more environment-friendly and sustainable.
(2) Compared with other similar catalytic systems, the magnetic catalyst used in the invention is cheaper and easy to recover, namely, the catalyst is separated from the reaction mixed system by using a magnet.
Drawings
FIG. 1 shows catalyst Fe3O4@SiO2@CS-SO3NH of H3-a TPD map;
FIG. 2 shows catalyst Fe3O4@SiO2@CS-SO3XRD pattern of H;
FIG. 3 shows catalyst Fe3O4@SiO2@CS-SO3A TGA profile of H;
FIG. 4 shows catalyst Fe3O4@SiO2@CS-SO3FT-IR plot of H;
FIG. 5 shows catalyst Fe3O4@SiO2@CS-SOH3XPS spectrum (A is scanning catalyst Fe)3O4@SiO2@CS-SOH3B is Fe 2p, C is O1 s);
FIG. 6 is a mass spectrum of 2, 5-dimethyl-1-phenylpyrrole.
Detailed Description
The technical solutions of the present invention will be described in further detail with reference to examples, but they are not intended to limit the present invention.
Example 1
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol of 2, 5-dimethylfuran, 1mmol of aniline, 14.4mg of catalyst, 200. mu.L of distilled water and 2mL of anhydrous methanol were put into a high-pressure reactor and reacted at 170 ℃ for 3 hours. The conversion of 2, 5-dimethylfuran was determined by GC to be 96.1% and the yield of 2, 5-dimethyl-1-phenylpyrrole was determined to be 79.9%.
Example 2
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol2, 5-dimethylfuran, 1mmol aniline, 14.4mg catalyst, 200. mu.L distilled water and 2mL absolute methanol were added to an autoclave and reacted at 150 ℃ for 3 hours. The conversion of 2, 5-dimethylfuran was determined by GC to be 96.1% and the yield of 2, 5-dimethyl-1-phenylpyrrole was determined to be 79.7%
Example 3
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol of 2, 5-dimethylfuran, 1mmol of aniline, 14.4mg of catalyst, 200. mu.L of distilled water and 2mL of anhydrous methanol were put into a high-pressure reactor and reacted at 110 ℃ for 3 hours. The conversion of 2, 5-dimethylfuran was 77.6% and the yield of 2, 5-dimethyl-1-phenylpyrrole was 29.2% by GC.
Example 4
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol2, 5-dimethylfuran, 1mmol aniline, 14.4mg catalyst, 200. mu.L distilled water and 2mL anhydrous methanol were added to an autoclave and reacted at 170 ℃ for 2.5 h. The conversion of 2, 5-dimethylfuran was determined by GC to be 95.8% and the yield of 2, 5-dimethyl-1-phenylpyrrole to be 83.8%.
Example 5
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol of 2, 5-dimethylfuran, 1mmol of aniline, 14.4mg of catalyst, 200. mu.L of distilled water and 2mL of anhydrous methanol were put into a high-pressure reactor and reacted at 110 ℃ for 1 hour. The conversion of 2, 5-dimethylfuran was determined by GC to be 51.2% and the yield of 2, 5-dimethyl-1-phenylpyrrole was 8.8%.
Example 6
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol of 2, 5-dimethylfuran, 1mmol of aniline, 14.4mg of catalyst, 200. mu.L of distilled water and 2mL of an organic solvent (methanol, DMF, dichloromethane, absolute ethanol, tetrahydrofuran, cyclohexane, n-propanol or n-butanol) were put into a high-pressure reactor and reacted at 170 ℃ for 2.5 hours. The yields of 2, 5-dimethyl-1-phenylpyrrole determined by GC are shown in table 1.
TABLE 1 yield of 2, 5-dimethyl-1-phenylpyrrole in different solvents
Example 7
One-pot method for catalytic synthesis of 2, 5-dimethyl-1-phenylpyrrole by using magnetic catalyst
1mmol of 2, 5-dimethylfuran, 1mmol of aniline, 14.4mg of catalyst, distilled water (50-300. mu.L) and 2mL of methanol as solvents were added together to a high-pressure reaction vessel and reacted at 170 ℃ for 2.5 hours. The yields of 2, 5-dimethyl-1-phenylpyrrole determined by GC are shown in table 2.
TABLE 2 yield of 2, 5-dimethyl-1-phenylpyrrole at different water contents
Serial number
|
Water content (μ L)
|
Yield (%)
|
1
|
50
|
66.0
|
2
|
100
|
82.9
|
3
|
150
|
82.1
|
4
|
200
|
88.9
|
5
|
250
|
82.3
|
6
|
300
|
68.6 |
Example 8
Catalytic synthesis of 2, 5-dimethyl-1- (3-methylphenyl) -pyrrole by oil bath pan
1mmol2, 5-dimethylfuran, 1mmol 3-methylaniline, 14.4mg catalyst, 200. mu.L distilled water and 2mL of anhydrous methanol were added to a high pressure reaction vessel and reacted at 170 ℃ for 2.5 hours. Determination of 2, 5-dimethyl-1- (3-methyl) by GCPhenyl) -pyrrole yield was 82.5%. Mass spectrum data of 2, 5-dimethyl-1- (3-methylphenyl) -pyrrole is M/z 185.7 (M)+)、170.2、154.4、129.2、91.5、65.3、51.7。
Example 9
Catalytic synthesis of 2, 5-dimethyl-1- (2-methylphenyl) -pyrrole by oil bath pan
1mmol2, 5-dimethylfuran, 1mmol 2-methylaniline, 14.4mg catalyst, 200uL distilled water and 2mL of anhydrous methanol were added to a high pressure reaction vessel and reacted at 170 ℃ for 2.5 h. The yield of 2, 5-dimethyl-1- (2-methylphenyl) -pyrrole was 78.3% by GC. Mass spectral data of 2, 5-dimethyl-1- (2-methylphenyl) -pyrrole is M/z 185.7 (M)+)、170.2、154.4、91.5、51.7。
Example 10
Oil bath pan catalyzed synthesis of 2, 5-dimethyl-1- (4-methoxyphenyl) -pyrrole
Adding 1mmol2, 5-dimethylfuran, 1mmol p-anisidine, 14.4mg catalyst, 2mL absolute methanol and 200uL distilled water into a high-pressure reaction kettle, and reacting at 170 ℃ for 2.5h to obtain the product. The yield of 2, 5-dimethyl-1- (3-fluorophenyl) -pyrrole was 46.65% by GC. Mass spectrum data of 2, 5-dimethyl-1- (4-methoxyphenyl) -pyrrole is M/z 201.8 (M)+)、186.7、160.2、144.8、117.6、77.2、62.8、39.1。
Example 11
Oil bath pan catalyzed synthesis of 2, 5-dimethyl-1-butyl-pyrrole
1mmol of 2, 5-dimethylfuran, 1mmol of n-butylamine, 14.4mg of a catalyst, 200uL of distilled water and 2mL of anhydrous methanol were put into a high-pressure reaction vessel and reacted at 170 ℃ for 2.5 hours. The yield of 2, 5-dimethyl-1-butyl-pyrrole was determined by GC to be 2.3%. Mass spectral data of 2, 5-dimethyl-1-butyl-pyrrole is M/z151.6 (M)+)、136.2、108.2、94.2。