Preparation method of 4-benzoyl pyridine derivative

Abstract

The invention relates to the technical field of benzoyl pyridine synthesis, in particular to a preparation method of a 4-benzoyl pyridine derivative, which comprises the following steps: uniformly mixing a 4-benzylpyridine derivative, an iron-based catalytic material and water, introducing oxygen, and reacting at a set temperature for a set time to obtain the 4-benzoyl pyridine derivative, green and economical molecular oxygen is used as an oxidizing agent, water is used as a solvent, and 4-benzyl pyridine and the derivative thereof are efficiently oxidized to obtain the corresponding 4-benzoyl pyridine derivative. The method is simple to operate and mild in reaction condition, and water is used as a solvent, so that the economic and environmental cost is greatly reduced.

Description

Technical Field

[0001] This invention relates to the technical field of benzoylpyridine synthesis, and in particular to a method for preparing a 4-benzoylpyridine derivative. Background Technology

[0002] 4-Benzoylpyridine, as an important organic synthesis intermediate, has wide applications in the fields of chemistry and medicine. It can participate in the construction of complex compounds through various reactions, such as the synthesis of heterocyclic compounds containing pyridine rings, drug precursors, and functional material intermediates. In some drug development, its structural units can provide specific biological activities or physicochemical properties to molecules. Simultaneously, it can also act as a ligand to form complexes with metal ions for catalytic reactions or materials science research. Furthermore, in organic synthetic chemistry, it is often used as a key building block for constructing more complex molecular skeletons, driving synthetic innovation and application development in related fields.

[0003] The oxidation of benzylpyridine to obtain 4-benzoylpyridine is an important synthetic method. However, most of the catalytic systems currently studied have limitations: most oxidation systems use organic solvents (DMA, DMF, DMSO, chlorobenzene), which are not environmentally friendly; the polyacid catalysts used (such as heteropolyoxovanadates) are complex to synthesize and have poor stability, resulting in high costs; the reaction often requires strong oxidants (such as TBHP, Na2S2O8, etc.), which can cause side reactions or safety issues; and catalytic systems using molecular oxygen O2 as an oxidant have problems such as requiring large amounts of molecular oxygen O2 or the need for additives.

[0004] Water is an environmentally friendly green solvent, and developing a highly efficient catalytic system for the oxidation of benzylpyridine molecules using water as a solvent has important practical significance.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing 4-benzoylpyridine derivatives. Using green and economical molecular oxygen as an oxidant and water as a solvent, 4-benzylpyridine and its derivatives are efficiently oxidized to obtain the corresponding 4-benzoylpyridine derivatives. This invention is simple to operate, has mild reaction conditions, and uses water as a solvent, which greatly reduces economic and environmental costs.

[0007] The present invention provides a method for preparing a 4-benzoylpyridine derivative, comprising: uniformly mixing a 4-benzylpyridine derivative, an iron-based catalyst and water, introducing oxygen, and reacting at a set temperature for a set time to obtain the 4-benzoylpyridine derivative.

[0008] More specifically, firstly, the surface of the iron-based catalyst is covered with organic molecules, which gives it a stronger affinity for oil than conventional inorganic catalysts. In aqueous systems, it repels water but has better compatibility with benzylpyridine molecules, which is beneficial for the contact activation of reactant molecules and catalysts.

[0009] Secondly, the iron-based catalytic material structure simultaneously contains Fe, which activates molecular oxygen. 2+ Species and Fe with strong electron acceptance 3+ Through sequential hydrogen atom transfer and electron transfer processes, 4-benzylpyridine derivatives can be converted into reactive carbocation intermediates. The reaction equation is as follows (taking 4-benzylpyridine as an example):

[0010]

[0011] Finally, unlike the traditional pathway where free radical intermediates react directly with molecular oxygen to form peroxides, in this reaction system, water reacts with the carbocation intermediate to form an intermediate alcohol, which is further oxidized to generate a 4-benzoylpyridine derivative. The reaction equation is as follows (taking 4-benzylpyridine as an example):

[0012]

[0013] As a preferred embodiment of the present invention, the iron-based catalytic material is an organic-inorganic hybrid material synthesized by reacting Fe-containing hydrotalcite with organic acids.

[0014] As a preferred embodiment of the present invention, the iron-based catalytic material further includes at least one of Ni, Mg and Al.

[0015] More specifically, the introduction of the aforementioned metals can regulate the electron density of Fe species, thereby modulating their activation ability for molecular oxygen; they can also synergistically construct a more stable hybrid framework with Fe, inhibiting Fe... 2+ / Fe 3+ The aggregation or loss of catalysts can extend their service life.

[0016] As a preferred embodiment of the present invention, the organic acid includes at least one of hexanoic acid, valeric acid, benzoic acid and butyric acid.

[0017] More specifically, the aforementioned organic acids contain alkyl or aryl groups of varying chain lengths. Through reaction with Fe-containing hydrotalcites, suitable hydrophobic groups are introduced onto the material surface, resulting in a more precise match with 4-benzylpyridine derivatives and promoting efficient substrate adsorption and activation. Simultaneously, their carboxyl groups can form stable coordination with the metal ions of the hydrotalcite-like minerals, enhancing the organic-inorganic interface and reducing the shedding of organic components during the reaction. Furthermore, these organic acids possess moderate acidity, avoiding excessive disruption of the layered structure of the hydrotalcite-like minerals while simultaneously allowing the reaction between the acid radical and Fe...2+ / Fe 3+ The interaction modulates its electronic state, optimizes the efficiency of hydrogen atom transfer and carbocation intermediate formation, and ultimately improves reaction selectivity and target product yield.

[0018] As a preferred embodiment of the present invention, the method for preparing iron-based catalytic materials includes:

[0019] Fe-containing hydrotalcite, organic acid and n-alkanes are mixed and heated and stirred for 20-48 hours. After the reaction is completed, the mixture is filtered and washed, and then dried in an oven at 70-100℃ to obtain the iron-based catalyst.

[0020] More specifically, in the above process, Fe-containing hydrotalcites serve as an inorganic framework, providing reactive Fe. 2+ / Fe 3+ With the presence of metal ions and layered structures, organic acids can coordinate with metal ions in hydrotalcite-like materials through carboxyl groups or replace some interlayer anions, thereby regulating the electronic properties of the central metal ion.

[0021] n-Alkanes, as hydrophobic reaction media, provide a suitable environment for interfacial reactions between low-polarity organic acids and high-polarity Fe-based hydrotalcites, reducing the repulsion caused by polarity differences and promoting full contact and uniform reaction between the two.

[0022] Heating and stirring accelerate the interaction between organic acids and the surface / layers of hydrotalcite by increasing molecular kinetic energy. Washing removes unreacted free organic acids and n-alkanes. Drying at 70-100℃ removes residual solvents and moisture, ultimately forming an organic-inorganic hybrid material with organic acid-derived organic groups on the surface, retaining the layered structure of Fe hydrotalcite and active Fe species inside. This lays the structural foundation for substrate activation and oxygen molecule utilization in subsequent catalytic reactions.

[0023] As a preferred embodiment of the present invention, the temperature is set to 80-100°C and the time is set to 12-48 hours.

[0024] More specifically, 80–100℃ can provide sufficient energy to activate Fe on the surface of iron-based catalysts. 2+ / Fe 3+ The active site accelerates the adsorption and activation of O2 molecules and the hydrogen atom transfer process, promoting the formation of carbocation intermediates; it also avoids catalyst deactivation caused by high temperature (such as Fe species aggregation or organic ligand decomposition) and the aggravation of side reactions (such as excessive oxidation to produce carboxylic acids).

[0025] As a preferred embodiment of the present invention, the amount of iron-based catalytic material relative to each mole of 4-benzylpyridine derivative is 100-200g.

[0026] More specifically, the lower limit of 100g can avoid the lack of active sites caused by insufficient catalyst dosage, and prevent the reaction rate from being too slow and the conversion rate from being too low; while the upper limit of 200g can avoid the waste of resources caused by excessive catalyst, and at the same time reduce the increase in mass transfer resistance caused by catalyst accumulation, thereby maintaining a high catalytic efficiency.

[0027] As a preferred embodiment of the present invention, the molar ratio of oxygen to 4-benzylpyridine derivative is 10 to 100:1.

[0028] More specifically, a lower limit of 10:1 ensures sufficient oxidant in the system, avoiding incomplete oxidation of raw materials and low conversion rate due to insufficient oxygen, while an upper limit of 100:1 avoids resource waste caused by excessive oxygen.

[0029] In the prior art, the molar ratio of oxygen to 4-benzylpyridine derivative is about 300-500:1. The amount of oxygen required in this invention is greatly reduced because the iron-based catalytic material can specifically promote the directional conversion of benzyl to benzoyl groups and suppress the ineffective consumption of oxygen by side reactions.

[0030] As a preferred embodiment of the present invention, the molar ratio of water to the 4-benzylpyridine derivative is 200 to 300:1.

[0031] More specifically, low water usage affects mass transfer in the reaction system and reduces catalytic reaction efficiency; excessive water usage results in low concentrations of reactants and catalysts, which also affects catalytic efficiency.

[0032] As a preferred embodiment of the present invention, the system is under normal pressure when oxygen is introduced. Normal pressure reaction does not require high pressure reaction equipment and conventional open or simple sealed reactors can be used directly, which greatly reduces the special requirements for equipment pressure resistance and airtightness.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention uses green and economical molecular oxygen as an oxidant and water as a solvent to efficiently oxidize 4-benzylpyridine and its derivatives to obtain the corresponding 4-benzoylpyridine derivatives. The present invention is simple to operate, has mild reaction conditions, and uses water as a solvent, which greatly reduces economic and environmental costs.

[0034] This invention uses heterogeneous iron-based materials as catalysts, which can be reused. It solves the problem of low catalyst selectivity in existing systems and has the advantages of simple reaction system, good product selectivity, reusable catalyst, and simple process flow, and has good application prospects. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below.

[0036] In specific embodiments of the present invention, the sources of each commercially available material are shown in Table 1:

[0037] Table 1: Sources of Commercially Available Materials

[0038]

[0039] The preparation methods of iron-based catalytic materials include the following three approaches:

[0040] (1) 100 mg of Mg2Fe-type hydrotalcite (Mg2Fe-LDH), 0.3 mmol of benzoic acid (BA) and 2 mL of dodecane were added to the reactor and reacted at 120 °C for 20 h with stirring. After the reaction was completed, the mixture was filtered and washed with ethyl acetate. Then it was dried in an oven at 80 °C for 12 h to obtain the iron-based catalyst BA-Mg2Fe.

[0041] (2) 100 mg of Mg2Fe hydrotalcite, 0.1 mmol of hexanoic acid (HA) and 2 mL of hexane were added to the reactor and reacted at 80 °C for 36 h with stirring. After the reaction was completed, the mixture was filtered and washed with ethyl acetate. Then it was dried in an oven at 80 °C for 12 h to obtain the iron-based catalyst HA-Mg2Fe.

[0042] (3) Add 100 mg of Mg2Fe-type hydrotalcite, 0.4 mmol of n-butyric acid (BTA) and 2 mL of n-nonane to the reactor, and react for 10 h under stirring at 140 °C. After the reaction is completed, filter and wash with ethyl acetate, and then dry in an oven at 80 °C for 12 h to obtain iron-based catalyst BTA-Mg2Fe.

[0043] In the examples and comparative examples, the conversion rate = (m1 / m2)*100%, where m1 is the weight of the 4-benzylpyridine derivative consumed in the reaction, and m2 is the weight of the initially added 4-benzylpyridine derivative.

[0044] Selectivity = (m3 / m4)*100%, where m3 is the amount of 4-benzoylpyridine derivative generated and m4 is the amount of 4-benzylpyridine derivative consumed in the reaction.

[0045] Yield = Conversion Rate * Selectivity;

[0046] Example 1

[0047] 0.5 mmol of 4-benzylpyridine, 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 90 °C and 400 r / min for 24 h.

[0048] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 92.0% and the selectivity was 93.5%.

[0049] Example 2

[0050] 0.5 mmol of 4-benzylpyridine, 80 mg of HA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 90 °C and 400 r / min for 24 h.

[0051] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 88.2% and the selectivity was 90.5%.

[0052] Example 3

[0053] 0.5 mmol of 4-benzylpyridine, 80 mg of BTA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 90 °C and 400 r / min for 24 h.

[0054] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 90.5% and the selectivity was 94.2%.

[0055] Example 4

[0056] 0.5 mmol of 4-benzylpyridine, 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to a reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 80:1. The reaction was carried out at 80 °C and 400 r / min for 12 h. The mass of the reactant 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution were analyzed by gas chromatography with internal standard method, using biphenyl as the internal standard. The calculated conversion rate was 44.3%, and the selectivity was 83.2%.

[0057] Example 5

[0058] 0.5 mmol of 4-benzylpyridine, 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 90 °C and 400 r / min for 36 h.

[0059] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 99.0% and the selectivity was 93.0%.

[0060] Example 6

[0061] 0.5 mmol of 4-benzylpyridine, 100 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 100:1. The reaction was carried out at 90 °C and 400 r / min for 12 h.

[0062] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 79.9% and the selectivity was 94.8%.

[0063] Example 7

[0064] 0.5 mmol of 4-benzylpyridine, 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 100 °C and 400 r / min for 12 h.

[0065] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 76.2% and the selectivity was 86.2%.

[0066] Example 8

[0067] 1.0 mmol of 4-benzylpyridine, 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 10:1. The reaction was carried out at 90 °C and 400 r / min for 12 h.

[0068] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 74.7% and the selectivity was 90.6%.

[0069] Example 9

[0070] 0.5 mmol of 4-benzylpyridine, 50 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced under stirring, with an oxygen / 4-benzylpyridine molar ratio of 50:1. The reaction was carried out at 90 °C and 400 r / min for 12 h.

[0071] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, and biphenyl was used as internal standard. The conversion rate of the reaction was calculated to be 81.2% and the selectivity was 93.0%.

[0072] Examples 10-19 (replacing the R group in RC6H5CH2C5H4N), the reaction equations are as follows:

[0073]

[0074] 0.5 mmol of 4-benzylpyridine derivatives (1b–1k), 80 mg of BA-Mg2Fe catalyst, and 2 mL of deionized water were added to the reactor. Oxygen was introduced and the mixture was heated to 90 °C at a rotation speed of 400 r / min for 24–48 h. The yield of the reaction was analyzed by GC-MS normalization. The structure of the products (2b–2k) was confirmed by NMR spectroscopy. The results are shown in Table 2.

[0075] Table 2: Raw materials, products, time, and yield results for Examples 1 and 10-19

[0076]

[0077]

[0078]

[0079] The products of Examples 10-19 are characterized as follows:

[0080] 4-Benzoylpyridine (2a), yellow solid; 1 H NMR (600MHz, CDCl3) δ8.83(d,J=5.8Hz,2H),7.89–7.80(m,2H),7.69–7.64(m,1H),7.60(dd,J=4.4,1.6Hz,2H),7.53(t,J=7.8Hz,2H). 13 C NMR (126MHz, CDCl3) δ195.2,150.3,144.4,135.9,133.6,130.2,128.7,122.9.

[0081] (4-Nitrophenyl)(pyridin-4-yl)methyl ketone (2b), white solid; 1H NMR (600MHz, CDCl3) δ8.80(d,J=5.5Hz,2H),8.30(d,J=8.6Hz,2H),7.91(d,J=8.6Hz,2H),7.52(d,J=5.5Hz,2H). 13 CNMR (126MHz, CDCl3) δ193.50,150.78,150.41,142.80,140.78,130.93,123.87,122.66.

[0082] 4-Pyridyl[4-(trifluoromethyl)phenyl]methyl ketone (2c), white solid; 1 H NMR (600MHz, CDCl3) δ8.77(dd,J=4.5,1.5Hz,2H),7.85(d,J=8.1Hz,2H),7.72(d,J=8.2Hz,2H),7.52(dd,J=4.4,1.5Hz,2H). 13 C NMR (126MHz, CDCl3) δ193.09,149.59,142.36,137.81,134.06,133.84,133.63,133.41,129.28,124.73,123.34,121.77.

[0083] 4-(4-pyridylcarbonyl)benzyl nitrile (2d), yellow solid; 1 H NMR (600MHz, CDCl3) δ8.80(dd,J=4.4,1.6Hz,2H),7.73(d,J=8.2Hz,2H),7.57(dd,J=4.4,1.6Hz,2H),7.31(d,J=8.0Hz,2H). 13 CNMR (126MHz, CDCl3) δ194.80,150.16,144.92,144.69,133.25,130.36,130.15,129.38,128.6.

[0084] 4-(4-fluorobenzoyl)pyridine (2e), white solid; 1 H NMR (600MHz, CDCl3) δ8.82(dd,J=4.4,1.6Hz,2H),8.00–7.71(m,2H),7.56(dd,J=4.4,1.6Hz,2H),7.23–7.16(m,2H). 13 C NMR (126MHz, CDCl3) δ193.63,166.86,165.16,150.44,144.28,132.87,122.71,116.04,115.89.

[0085] 4-(4-chlorobenzyloxy)pyridine (2f), white solid; 1 H NMR (600MHz, CDCl3) δ8.77(dd,J=4.3,1.6Hz,2H),7.75–7.69(m,2H),7.51(dd,J=4.3,1.6Hz,2H),7.46–7.41(m,2H). 13 C NMR (126MHz, CDCl3) δ193.8,150.4,143.9,140.1,134.1,131.5,129.0,122.7.

[0086] (4-Bromophenyl)-4-pyridine-benzene (2g), white solid; 1 H NMR (600MHz, CDCl3) δ8.93–8.73(m,2H),8.73–7.58(m,4H),7.56(dd,J=4.4,1.5Hz,2H). 13 C NMR (126MHz, CDCl3) δ194.11,150.49,143.91,134.60,132.06,131.56,128.92,122.83–122.61.

[0087] (4-Methoxyphenyl)(4-pyridyl)methyl ketone (2h), white solid; 1 H NMR (600MHz, CDCl3) δ8.79(dd,J=4.3,1.6Hz,2H),7.83(d,J=8.9Hz,2H),7.54(dd,J=4.3,1.6Hz,2H),6.99(d,J=8.9Hz,2H),3.90(s,3H) 13 C NMR (126MHz, CDCl3) δ193.76,164.07,150.25,145.26,132.69,128.64,122.73,113.97,55.62.

[0088] 4-(4-Toluene-2-pyridine) (2i), yellow solid; 1 H NMR (600MHz, CDCl3) δ8.86 (dd, J = 4.5, 1.4Hz, 2H), 7.92 (d, J = 8.4Hz, 2H), 7.85 (d, J = 8.4Hz, 2H), 7.59 (d, J = 5.9Hz, 2H), 1.34 (s, 3H). 13C NMR (126MHz, CDCl3) δ194.80,150.17,144.92,144.69,133.25,130.35,129.38,128.68,122.90,21.76.

[0089] 4-Isonicotinylbenzoate (2j), a yellow oily substance; 1 H NMR (600MHz, CDCl3) δ8.84 (dd, J=4.4, 1.6Hz, 2H), 8.19 (d, J=8.4Hz, 2H), 7.87 (d, J=8 .4Hz,2H),7.60(dd,J=4.4,1.6Hz,2H),4.44(q,J=7.1Hz,2H),1.44(t,J=7.1Hz,3H). 13 C NMR (126MHz, CDCl3) δ194.54,165.48,150.48,143.60,139.18,134.54,129.78,122.81,61.57,14.24.

[0090] 2-Naphthyl(pyridin-4-yl)methyl ketone (2k), white solid; 1 H NMR(600MHz, CDCl3)δ8.75(d,J=5.7Hz,2H),8.15(s,1H),7.87(d,J=0.4Hz,2H),7 .83(d,J=8.6Hz,2H),7.55(dd,J=11.2,3.4Hz,3H),7.48(dd,J=11.4,4.4Hz,1H). 13 C NMR (126MHz, CDCl3) δ194.05,149.27,143.77,134.66,132.11,131.57,131.14,128.57,127.98,127.77,126.86,126.11,124.06,121.94.

[0091] Comparative Example 1

[0092] Unlike Example 1, no iron-based catalyst BA-Mg2Fe was added. The steps were as follows: 0.5 mmol of 4-benzylpyridine and 2 mL of deionized water were added to the reactor, oxygen was introduced, and the molar ratio of oxygen to 4-benzylpyridine was 50:1. The reaction was carried out at a temperature of 90°C and a rotation speed of 400 r / min for 24 h.

[0093] The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution was analyzed by gas chromatography with internal standard method, using biphenyl as the internal standard. The calculated conversion rate was 1.5%, and the selectivity was 99%.

[0094] Compared to Example 1, no catalyst was added in Comparative Example 1. The results showed that the conversion rate of 4-benzylpyridine and the yield of 4-benzoylpyridine were significantly reduced, indicating that the addition of the catalyst BA-Mg2Fe has a significant promoting effect on the conversion of 4-benzylpyridine.

[0095] Comparative Example 2

[0096] Unlike Example 1, air was used instead of oxygen. The steps were as follows: 0.5 mmol of 4-benzylpyridine, 2 mL of deionized water, and 80 mg of BA-Mg2Fe catalyst were added to the reactor. Air was introduced, and the reaction was carried out at 90°C and 400 r / min for 24 h. The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution were analyzed by gas chromatography with internal standard method, using biphenyl as the internal standard. The calculated conversion rate was 69.8%, and the selectivity was 86.1%.

[0097] Compared to Example 1, Comparative Example 2 used air as the oxidant, and the conversion rate of 4-benzylpyridine was significantly reduced. This indicates that molecular oxygen plays a key role as an oxidant in the oxidation process. The reduced oxygen concentration in the air affected the catalytic activation ability of the catalyst, resulting in a decrease in the conversion rate of 4-benzylpyridine and thus affecting the conversion rate of the reactants.

[0098] Comparative Example 3

[0099] Unlike Example 1, MgO, Mg2Al-LDH, and Fe2O3 were used instead of the BA-Mg2Fe catalyst. The steps were as follows: 0.5 mmol of 4-benzylpyridine, 2 mL of deionized water, and 80 mg each of catalysts MgO, Mg2Al-LDH, and Fe2O3 were added to the reactor. Air was introduced, and the reaction was carried out at 90°C and 400 r / min for 24 h. The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution were analyzed by gas chromatography with internal standard method, using biphenyl as the internal standard. Calculations showed that the conversion rate was less than 3% when using MgO and Mg2Al-LDH as catalysts, and 6.4% when using Fe2O3 as catalysts.

[0100] Compared to Example 1, Comparative Example 3 used MgO, Mg2Al-LDH, and Fe2O3 as catalysts. The results showed that the conversion rate of 4-benzylpyridine was significantly reduced, indicating the key role of Fe in the catalyst.

[0101] Comparative Example 4

[0102] Unlike Example 1, untreated Mg2Fe-LD was used instead of the BA-Mg2Fe catalyst. The steps were as follows: 0.5 mmol of 4-benzylpyridine, 2 mL of deionized water, and 80 mg of Mg2Fe-LDH catalyst were added to the reactor. Oxygen was introduced, with a molar ratio of oxygen to 4-benzylpyridine of 50:1. The reaction was carried out at 90°C and 400 r / min for 24 h. The mass of the raw material 4-benzylpyridine and the product 4-benzoylpyridine in the reaction solution were analyzed by gas chromatography with internal standard method, using biphenyl as the internal standard. The calculated conversion rate was 4.6%, and the selectivity was 88.9%.

[0103] Compared to Example 1, Comparative Example 4 used Mg2Fe-LDH as a catalyst, and the results showed that the conversion rate of 4-benzylpyridine was significantly reduced. This indicates that the catalytic activity of Mg2Fe-LDH is not as good as that of BA-Mg2Fe, and that the hybrid material that successfully hybridizes with organic acid has a significant promoting effect on the conversion of 4-benzylpyridine.

[0104] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a 4-benzoylpyridine derivative, characterized in that, include: A 4-benzylpyridine derivative, an iron-based catalyst, and water were uniformly mixed, oxygen was introduced, and the mixture was reacted at a set temperature for a set time to obtain the 4-benzoylpyridine derivative.

2. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The iron-based catalytic material is an organic-inorganic hybrid material synthesized by reacting Fe-containing hydrotalcite with organic acids.

3. The method for preparing the 4-benzoylpyridine derivative as described in claim 2, characterized in that, The iron-based catalytic material also includes at least one of Ni, Mg and Al.

4. The method for preparing the 4-benzoylpyridine derivative as described in claim 2, characterized in that, The organic acid includes at least one of hexanoic acid, valeric acid, benzoic acid, and butyric acid.

5. The method for preparing the 4-benzoylpyridine derivative as described in claim 2, characterized in that, The preparation method of the iron-based catalytic material includes: Fe-containing hydrotalcite, organic acid and n-alkanes are mixed and heated and stirred for 20-48 hours. After the reaction is completed, the mixture is filtered and washed, and then dried in an oven at 70-100℃ to obtain the iron-based catalytic material.

6. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The set temperature is 80~100℃; the set time is 12~48h.

7. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The amount of the iron-based catalytic material used is 100-200g per mole of 4-benzylpyridine derivative.

8. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The molar ratio of oxygen to the 4-benzylpyridine derivative is 10~100:

1.

9. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The molar ratio of water to the 4-benzylpyridine derivative is 200-300:

1.

10. The method for preparing the 4-benzoylpyridine derivative as described in claim 1, characterized in that, The system is under normal pressure when oxygen is introduced.

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