Methyl acetoacrylate, preparation method thereof and preparation method of acetoacrylic acid

Abstract

The invention relates to the technical field of chemical synthesis of acetoacrylic acid and methyl ester thereof, and discloses methyl acetoacrylate and a preparation method thereof and a preparation method of acetoacrylic acid.The method comprises the steps that 1, in oxygen-containing gas, in the presence of an organic photosensitizer, 5-methylfurfural is subjected to a photocatalytic oxidation reaction in a methanol solvent, and 5-methylfurfural is obtained; the 5-methyl-5-methoxy-2 (5H)-furanone is subjected to a reaction to obtain 5-methyl-5-methoxy-2 (5H The wavelength of light in the photocatalytic oxidation reaction is 400 to 800 nm; (2) in the presence of hafnium trifluoromethanesulfonate, carrying out an isomerization reaction on the 5-methyl-5-methoxy-2 (5H)-furanone in a solvent 1 to obtain methyl acetoacrylate; the solvent 1 comprises dichloromethane and / or deuterated chloroform. According to the preparation method disclosed by the invention, high-selectivity acetoacrylic acid or methyl acetoacrylate can be obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis of acetylacrylic acid and its methyl ester, and specifically relates to methyl acetylacrylate and its preparation method, and the preparation method of acetylacrylic acid. Background Art

[0002] In recent years, photocatalytic technology, as a powerful alternative to traditional heterogeneous thermal catalysis, has been widely studied and applied, especially showing great potential in the synthesis of furan compounds. Photocatalysis can not only achieve reactions under mild light conditions, but more importantly, through the generation of free radical intermediates by light, it can achieve unconventional selectivities that are difficult to obtain by traditional heterogeneous thermal catalysis.

[0003] However, the current photocatalytic conversion of 5-methylfurfural is mainly limited to only the generation of furan compounds and cannot be effectively further converted and utilized, which limits the development and application scope of 5-methylfurfural.

[0004] CN114478445A discloses a method for photocatalytic oxidative reforming of biomass-based furan compounds, which includes the following steps: using 5-hydroxymethylfurfural and / or its derivatives as reaction substrates and adding them to an organic solvent, adding an organic photosensitizer, and then under an oxygen-containing atmosphere, using light for photocatalytic oxidation to obtain a reformed product; the wavelength of the light for the photocatalytic oxidation is 300 - 800 nm. However, this scheme has the problem of low yield of the main reaction product 3-acetylacrylic acid, which means that most of the MF may undergo side reactions and the selectivity of the reaction is poor.

[0005] Therefore, using 5-methylfurfural to obtain furan compounds and further improving the potential of furan biorefining is of great significance to the chemical industry. Summary of the Invention

[0006] The object of the present invention is to overcome the technical problems in the prior art that in the process of preparing acetylacrylic acid and its methyl ester from 5-methylfurfural, the conversion rate of 5-methylfurfural is low, and the yield and selectivity of acetylacrylic acid and its methyl ester are low.

[0007] To achieve the above object, the first aspect of the present invention provides a method for preparing methyl acetylacrylate, which includes:

[0008] (1) In an oxygen-containing gas and in the presence of an organic photosensitizer, subject 5-methylfurfural to photocatalytic oxidation reaction in a methanol solvent to obtain 5-methyl-5-methoxy-2(5H)-furanone; the wavelength of the light in the photocatalytic oxidation reaction is 400 - 800 nm;

[0009] (2) In the presence of hafnium trifluoromethanesulfonate, isomerize the 5-methyl-5-methoxy-2(5H)-furanone in Solvent 1 to obtain methyl acetylacrylate; Solvent 1 includes dichloromethane and / or deuterated chloroform.

[0010] The second aspect of the present invention provides methyl acetylacrylate prepared by the method described in the first aspect.

[0011] The third aspect of the present invention provides a method for preparing acetylacrylic acid, the method comprising:

[0012] (S1) Under an oxygen-containing gas and in the presence of an organic photosensitizer, carry out a photocatalytic oxidation reaction on 5-methylfurfural in an acetonitrile solvent to obtain Solution 1 containing 5-methyl-5-hydroxy-2(5H)-furanone; the wavelength of the light in the photocatalytic oxidation reaction is 400 - 800 nm;

[0013] (S2) Carry out an isomerization reaction on Solution 1 to obtain acetylacrylic acid; the conditions of the isomerization reaction include: temperature is 40 - 60 °C, and time is 24 - 36 h.

[0014] The present invention has at least the following advantages:

[0015] (1) By using the preparation method of the present invention, the conversion rate of 5-methylfurfural is high and high-yield and high-selectivity acetylacrylic acid or methyl acetylacrylate can be obtained.

[0016] (2) The preparation method of the present invention has the advantages of mild reaction conditions, simple operation and low production cost, and is suitable for large-scale industrial production. Detailed Embodiments

[0017] The endpoints and any values within the ranges disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0018] The selectivity in the present invention refers to the ratio of the actually converted raw material to the target product.

[0019] As described above, the first aspect of the present invention provides a method for preparing methyl acetylacrylate, the method comprising:

[0020] (1) In an oxygen-containing gas and in the presence of an organic photosensitizer, 5-methylfurfural is subjected to a photocatalytic oxidation reaction in a methanol solvent to obtain 5-methyl-5-methoxy-2(5H)-furanone; the wavelength of the light in the photocatalytic oxidation reaction is 400 - 800 nm;

[0021] (2) In the presence of hafnium trifluoromethanesulfonate, the 5-methyl-5-methoxy-2(5H)-furanone is subjected to an isomerization reaction in Solvent 1 to obtain methyl acryloylacetate; Solvent 1 includes dichloromethane and / or deuterated chloroform.

[0022] In the technical solution of the present invention, 5-methylfurfural is subjected to a photocatalytic oxidation reaction in a specific solvent to obtain a 5-methyl-5-methoxy-2(5H)-furanone intermediate, and the intermediate is subjected to a specific isomerization treatment to obtain methyl acryloylacetate with high yield and high selectivity.

[0023] Preferably, in step (2), the conditions of the isomerization reaction include: the temperature is 60 - 70 °C and the time is 24 - 39 h. The inventors of the present invention have found that under these preferred conditions, the yield and selectivity of the methyl acryloylacetate are higher.

[0024] Preferably, the photocatalytic reaction is carried out under stirring conditions, and the stirring speed is 300 - 800 rpm.

[0025] Preferably, in step (2), relative to every 1 mol of the 5-methyl-5-methoxy-2(5H)-furanone, the amount of hafnium trifluoromethanesulfonate used is 50 - 70 g.

[0026] Further preferably, in step (2), the concentration of the 5-methyl-5-methoxy-2(5H)-furanone in Solvent 1 is 0.14 - 0.17 mol / L.

[0027] Preferably, in step (1), the concentration of the 5-methylfurfural in the methanol solvent is 0.03 - 5 mol / L.

[0028] Further preferably, the molar amount of the organic photosensitizer accounts for 0.5 - 5% of the molar amount of the 5-methylfurfural, and more preferably 0.77 - 1.5%.

[0029] According to a preferred embodiment, the organic photosensitizer is selected from at least one of eosin Y, methylene blue, 9-mesityl-10-methylacridinium perchlorate, and rhodamine B; more preferably, the organic photosensitizer is eosin Y.

[0030] Preferably, the yield of the methyl acryloylacetate is 26.5 - 47%.

[0031] Preferably, the wavelength of the light in the photocatalytic oxidation reaction is 450 - 480 nm.

[0032] According to a particularly preferred embodiment, the method described in step (1) further includes: purifying the mixed solution obtained from the photocatalytic oxidation reaction to obtain the 5-methyl-5-methoxy-2(5H)-furanone;

[0033] The operations of the purification treatment include:

[0034] (1-1) Evaporating the mixed solution to obtain mixed solution 1; the temperature of the evaporation treatment is 100 - 150 °C;

[0035] (1-2) Distilling the mixed solution 1, and the fraction obtained during the distillation process is the 5-methyl-5-methoxy-2(5H)-furanone; the conditions of the distillation treatment include: the pressure is -0.1 Mpa to -0.09 Mpa, and the temperature is 200 °C - 230 °C.

[0036] More preferably, during the distillation treatment, when a dark brown substance appears at the branch nozzle of the distillation tube, the distillation is stopped. The inventors of the present invention found that under this preferred condition, the obtained 5-methyl-5-methoxy-2(5H)-furanone has a higher purity.

[0037] The present invention has no particular limitation on the time of the evaporation treatment in step (1-1), as long as the methanol solvent therein can be removed, so that the mass content of methanol in the mixed solution 1 ≤ 0.5 wt%.

[0038] Preferably, the volume fraction of oxygen in the oxygen-containing gas ≥ 21%, and more preferably, the oxygen-containing gas is oxygen or air.

[0039] More preferably, the solvent 1 is dichloromethane.

[0040] According to a particularly preferred embodiment, the photocatalytic oxidation reaction is carried out in a continuous reaction treatment mode. Specifically, the operations of the continuous reaction treatment include:

[0041] Mix the 5-methylfurfural, the organic photosensitizer, and the methanol solvent for the first time to obtain reaction solution 1, and transport reaction solution 1 to a gas-liquid mixer through a peristaltic pump; at the same time, transport the oxygen-containing gas to the gas-liquid mixer for a second mixing with reaction solution 1 to obtain reaction solution 2; then introduce reaction solution 2 into a photoreactor for the photocatalytic oxidation treatment; wherein, the photoreactor is formed by spirally winding a Teflon tube, and the complete passage of reaction solution 2 through the photoreactor is one cycle of reaction; in the photoreactor, after each cycle of reaction ends, take a sample and detect the conversion degree of 5-methylfurfural by thin-layer chromatography (TLC). If the 5-methylfurfural is not completely converted, continue with the next cycle of treatment until the complete conversion of 5-methylfurfural is achieved. ； Among them, when the spot corresponding to the raw material 5-methylfurfural on the TLC plate completely disappears, it indicates that the 5-methylfurfural is completely converted.

[0042] Preferably, the inner diameter of the Teflon tube is 2-4 mm, and the effective volume is 26-55 mL.

[0043] More preferably, the excitation light source in the photocatalytic oxidation reaction is an LED lamp placed on an aluminum alloy heat sink, and the excitation light source and the photoreactor are cooled by circulating water to avoid overheating of the light source and ensure a stable reaction temperature to maintain efficient photocatalytic conditions.

[0044] According to another preferred embodiment, in the present invention, toluene is used as an internal standard, and a gas chromatograph is used to sample and detect and analyze the components during the reaction process; wherein, the chromatographic column of the gas chromatograph is HP-5MS (30 m×0.25 mm×0.25 μm).

[0045] The inventors of the present invention found that using the internal standard method for quantitative analysis of the components during the reaction process has the advantages of high precision, good stability, strong comparability, and simple operation.

[0046] As described above, the second aspect of the present invention provides methyl acryloylacetate prepared by the method described in the first aspect.

[0047] Preferably, the purity of the methyl acryloylacetate is ≥95%.

[0048] As described above, the third aspect of the present invention provides a method for preparing acrylic acid, the method comprising:

[0049] (S1) Under an oxygen-containing gas and in the presence of an organic photosensitizer, carry out a photocatalytic oxidation reaction on 5-methylfurfural in an acetonitrile solvent to obtain solution 1 containing 5-methyl-5-hydroxy-2(5H)-furanone; the wavelength of the light in the photocatalytic oxidation reaction is 400-800 nm;

[0050] (S2) Isomerize the solution 1 to obtain acetoacrylic acid; the conditions for the isomerization reaction include: temperature is 40 - 60 °C, and time is 24 - 36 h.

[0051] In the technical solution of the present invention, 5 - methylfurfural is subjected to photocatalytic oxidation reaction in a specific solvent to obtain a 5 - methyl - 5 - hydroxy - 2(5H) - furanone intermediate, and the intermediate is subjected to specific isomerization treatment to obtain acetoacrylic acid with high yield and high selectivity.

[0052] Preferably, in step (S1), the concentration of 5 - methylfurfural in the acetonitrile solvent is 0.03 - 5 mol / L.

[0053] Preferably, in step (S1), the molar amount of the organic photosensitizer accounts for 0.5 - 5% of the molar amount of 5 - methylfurfural.

[0054] More preferably, the organic photosensitizer is selected from at least one of eosin Y, methylene blue, 9 - mesityl - 10 - methylacridinium perchlorate, and rhodamine B.

[0055] Preferably, the yield of acetoacrylic acid is 45 - 55%.

[0056] According to a preferred embodiment, toluene is used as an internal standard in the present invention, and a gas chromatograph is used to sample and detect the components during the reaction; among them, the chromatographic column of the gas chromatograph is HP - 5MS (30 m × 0.25 mm × 0.25 μm).

[0057] The inventors of the present invention found that using the internal standard method for quantitative analysis of the components during the reaction has the advantages of high precision, good stability, strong comparability, and simple operation.

[0058] In the following examples, unless otherwise specified, the raw materials are all ordinary commercially available products.

[0059] Dodecane: CAS No.: 112 - 40 - 3, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0060] Hafnium trifluoromethanesulfonate: CAS No.: 161337 - 67 - 3, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0061] Preparation Example 1

[0062] 5-Methylfurfural and methanol were added into a glass reaction tube with a side arm and ground glass stopper to form a solution. Then eosin Y was added, and a balloon filled with oxygen was installed at the top of the reaction tube, using oxygen as the oxidant. A 40 W blue LED lamp (wavelength λ = 467 nm) was used as the excitation light source (maintaining a distance of 2 mm between the excitation light source and the reaction tube wall), and a photocatalytic oxidation reaction was carried out with an air-cooled irradiation device to obtain a reaction solution containing 5-methyl-5-methoxy-2(5H)-furanone. Among them, the photocatalytic oxidation reaction was carried out under stirring conditions, and the stirring speed was 600 rpm. The specific process parameters are shown in Table 1.

[0063] Preparation Example 2

[0064] The same process flow as in Preparation Example 1 was used, except that methanol was replaced with an equal volume of acetonitrile, and the rest remained unchanged. A reaction solution containing 5-methyl-5-hydroxy-2(5H)-furanone was prepared, and the specific process parameters are shown in Table 1.

[0065] Preparation Example 3

[0066] (1) 5-Methylfurfural and methanol were added into a round-bottom flask to form a solution. Then eosin Y was added, and a 40 W blue LED lamp (wavelength λ = 467 nm) was used as the excitation light source (maintaining a distance of 2 mm between the excitation light source and the reaction tube wall), and a photocatalytic oxidation reaction was carried out with an air-cooled irradiation device to obtain a reaction solution containing 5-methyl-5-methoxy-2(5H)-furanone. Among them, the photocatalytic oxidation reaction was carried out under stirring conditions, and the stirring speed was 600 rpm. The specific process parameters are shown in Table 1;

[0067] Meanwhile, during the entire photocatalytic oxidation reaction, oxygen was continuously introduced into the flask to make the reaction system proceed in an oxygen atmosphere;

[0068] (2) The reaction solution obtained by photocatalytic oxidation treatment was evaporated by a rotary evaporator to remove the methanol solvent. The evaporation conditions were: temperature 100 - 150 °C, time 40 min;

[0069] The temperature was further increased for distillation treatment, and the fractions were collected to obtain 5-methyl-5-methoxy-2(5H)-furanone. The distillation conditions were: pressure -0.0975 MPa, temperature 200 - 230 °C. When a dark brown substance appeared at the side arm of the distillation head, the distillation was stopped. At this time, the gas fraction collected was 5-methyl-5-methoxy-2(5H)-furanone.

[0070] Preparation Example 4

[0071] The same process flow as in Preparation Example 3 was adopted, except that eosin Y was replaced with an equimolar amount of methylene blue, and the rest remained unchanged, to obtain 5-methyl-5-methoxy-2(5H)-furanone. The specific process parameters are shown in Table 1.

[0072] Preparation Example 5

[0073] In this preparation example, a continuous reaction device was used for the reaction. Specifically:

[0074] 5-Methylfurfural, methanol, and eosin Y were configured into a solution, and the solution was delivered to a gas-liquid mixer through a peristaltic pump at a rate of 3 mL / min. At the same time, oxygen with a flow rate of 50 mL / min was delivered to the gas-liquid mixer to be mixed with the solution, and the mixed solution was continuously introduced into a photoreactor formed by coiling a Teflon tube with an inner diameter of 2 mm for photocatalytic oxidation reaction. The effective volume of the photoreactor was 26 mL; the specific process parameters are shown in Table 1.

[0075] In the photocatalytic oxidation reaction, 2 LED lamps with a power of 144 W (wavelength = 450 nm) were used as the excitation light source, and the excitation light source was fixed on an aluminum alloy heat sink. The excitation light source device and the photoreactor were cooled by circulating cold water to avoid overheating of the light source and ensure the stability of the reaction temperature, maintaining an efficient photocatalytic oxidation reaction.

[0076] The solution mixed with oxygen passing completely through the photoreactor was one cycle of reaction. After each cycle of reaction ended, a sample was taken and the conversion degree of 5-methylfurfural was detected by thin-layer chromatography until 5-methylfurfural was completely converted, and the cycle reaction was stopped; a reaction solution containing 5-methyl-5-methoxy-2(5H)-furanone was obtained.

[0077] Preparation Examples 6 - 9

[0078] The same process flow as in Preparation Example 5 was adopted, except that the raw material components and process parameters were different, and the rest remained unchanged, to obtain a reaction solution containing 5-methyl-5-methoxy-2(5H)-furanone. The specific process parameters are shown in Table 1.

[0079] Table 1

[0080]

[0081] Note: The dosage / moL% of the organic photosensitizer refers to the molar percentage of the organic photosensitizer in 5-methylfurfural.

[0082] Test Example 1

[0083] After sampling the reaction solution containing 5-methyl-5-methoxy-2(5H)-furanone or the reaction solution containing 5-methyl-5-hydroxy-2(5H)-furanone obtained in the foregoing preparation example, toluene was added and analyzed using a gas chromatograph to determine the contents of 5-methyl-5-methoxy-2(5H)-furanone and 5-methyl-5-hydroxy-2(5H)-furanone, and the conversion rate of 5-methylfurfural and the yields of 5-methyl-5-methoxy-2(5H)-furanone and 5-methyl-5-hydroxy-2(5H)-furanone were calculated. The results are shown in Table 2;

[0084] The gas chromatography test conditions were as follows: The yields and conversion rates were determined by an Agilent 7890B gas chromatograph (GC) equipped with an HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm, Agilent). The typical temperature program of the GC column oven was as follows: The initial temperature was 80 °C, held for 2 min, then heated to 200 °C at a rate of 10 °C / min, and subsequently heated to 300 °C at a rate of 25 °C / min and held for 2 min;

[0085] The elution times of each component were as follows:

[0086] HP-5MS column: 5-methylfurfural (4.3 min), 5-methyl-5-methoxy-2(5H)-furanone (4.7 min), methyl acryloylacetate (5.1 min), 5-methyl-5-hydroxy-2(5H)-furanone (5.5 min), acryloylacetic acid (5.9 min);

[0087] Calculation method for conversion rate: Conversion rate = (1 - molar amount of 5-methylfurfural after reaction / molar amount of 5-methylfurfural before reaction) × 100%;

[0088] Calculation method for yield: Yield = molar amount of the target product after reaction / molar amount of 5-methylfurfural before reaction × 100%.

[0089] Test Example 2

[0090] The test method for the purity of 5-methyl-5-methoxy-2(5H)-furanone was as follows: The product purity was determined by nuclear magnetic resonance (NMR), and quantitative analysis was performed using the 1 1H NMR method combined with the internal standard method. The specific steps were as follows: First, a pure sample of 5-methoxy-5-methylfuran-2(5H)-one was taken, and 4-bromophenyl methyl ether with a known purity and no interaction with the product was selected as the internal standard, and the purity of the product was determined by nuclear magnetic resonance (NMR) spectroscopy; The results are shown in Table 2.

[0091] Table 2

[0092]

[0093]

[0094] Example 1

[0095] Hafnium trifluoromethanesulfonate and 5-methyl-5-methoxy-2(5H)-furanone prepared in Preparation Example 3 were added to 3 mL of deuterated chloroform solvent for isomerization reaction to obtain a reaction solution containing methyl acryloylacetate; the isomerization reaction was carried out under an oil bath condition, and the conditions of the isomerization reaction were: the temperature was 50 °C and the time was 14 h;

[0096] The concentration of 5-methyl-5-methoxy-2(5H)-furanone in the deuterated chloroform solvent was 0.15 mol / L; with respect to every 1 moL of 5-methyl-5-methoxy-2(5H)-furanone, the dosage of hafnium trifluoromethanesulfonate was 66.7 g.

[0097] Example 2

[0098] The same process flow as in Example 1 was adopted, the difference being that the time of the isomerization reaction was adjusted to 24 h, and the rest remained unchanged, to obtain a reaction solution containing methyl acryloylacetate.

[0099] Example 3

[0100] The same process flow as in Example 1 was adopted, the difference being that the time of the isomerization reaction was adjusted to 39 h, and the rest remained unchanged, to obtain a reaction solution containing methyl acryloylacetate.

[0101] Example 4

[0102] The same process flow as in Example 2 was adopted, the difference being that the temperature of the isomerization reaction was adjusted to 70 °C, and the rest remained unchanged, to obtain a reaction solution containing methyl acryloylacetate.

[0103] Example 5

[0104] The same process flow as in Example 4 was adopted, the difference being that deuterated chloroform was replaced with dichloromethane in an equal volume dosage, and the rest remained unchanged, to obtain a reaction solution containing methyl acryloylacetate, wherein the purity of methyl acryloylacetate was 95%;

[0105] In the present invention, it is not necessary to further purify the reaction solution containing methyl acryloylacetate. By testing the reaction solution with a gas chromatograph, methyl acryloylacetate with a purity of 95% can be determined.

[0106] Example 6

[0107] It is carried out using the same process flow as in Example 5, except that the temperature of the isomerization reaction is adjusted to 90 °C, and the rest remains unchanged, to obtain a reaction solution containing methyl acryloylformate.

[0108] Example 7

[0109] The reaction solution containing 5-methyl-5-hydroxy-2(5H)-furanone prepared in Preparation Example 2 is subjected to an isomerization reaction to obtain a reaction solution containing acryloylformic acid; the conditions of the isomerization reaction are: temperature is 50 °C, and time is 24 h.

[0110] Example 8

[0111] It is carried out using the same process flow as in Example 5, except that, with the amount of 5-methyl-5-methoxy-2(5H)-furanone remaining unchanged, the amount of hafnium trifluoromethanesulfonate is adjusted to 40 g relative to every 1 moL of 5-methyl-5-methoxy-2(5H)-furanone, and the rest remains unchanged, to obtain a reaction solution containing methyl acryloylformate.

[0112] Comparative Example 1

[0113] It is carried out using the same process flow as in Example 4, except that the deuterated chloroform solvent is replaced with dodecane solvent in an equal volume amount, and the rest remains unchanged, to obtain a reaction solution.

[0114] Comparative Example 2

[0115] It is carried out using the same process flow as in Example 4, except that the deuterated chloroform solvent is replaced with dimethylformamide solvent in an equal volume amount, and the rest remains unchanged, to obtain a reaction solution.

[0116] Comparative Example 3

[0117] It is carried out using the same process flow as in Example 4, except that hafnium trifluoromethanesulfonate is replaced with trifluoromethanesulfonic acid in an equal mass amount, and the rest remains unchanged, to obtain a reaction solution.

[0118] In the reaction solutions prepared from Comparative Examples 1-3, no methyl acryloylformate is formed, that is, if the specific preparation method of the present invention is not adopted, it is impossible to convert and generate methyl acryloylformate.

[0119] Comparative Example 4

[0120] It is carried out using the same process flow as in Example 7, except that: the temperature of the isomerization reaction is adjusted to 30 °C, and the rest remains unchanged, to obtain a reaction solution.

[0121] Test Example 3

[0122] Samples of the reaction solutions prepared in the foregoing examples and comparative examples were taken and toluene was added, and then detected and analyzed using a gas chromatograph-mass spectrometer. The conversion rate of 5-methyl-5-methoxy-2(5H)-furanone, the selectivity of methyl acryloylacetate, the conversion rate of 5-methylfurfural, the selectivity of the conversion of 5-methylfurfural to methyl acryloylacetate, and the purities of methyl acryloylacetate and methyl acrylate were calculated. The results are shown in Table 3;

[0123] The gas chromatography test conditions were as follows: The yields and conversion rates were determined by an Agilent 7890B gas chromatograph (GC) equipped with an HP-5MS capillary column (30 m × 0.25 mm × 0.25 μm, Agilent). The typical temperature program of the GC column oven was as follows: The initial temperature was 80 °C and held for 2 min, then heated to 200 °C at a rate of 10 °C / min, and subsequently heated to 300 °C at a rate of 25 °C / min and held for 2 min;

[0124] The peak elution times of each component were as follows:

[0125] HP-5MS column: 5-methylfurfural (4.3 min), 5-methyl-5-methoxy-2(5H)-furanone (4.7 min), methyl acryloylacetate (5.1 min), 5-methyl-5-hydroxy-2(5H)-furanone (5.5 min), methyl acrylate (5.9 min);

[0126] Calculation method for the conversion rate of 5-methyl-5-methoxy-2(5H)-furanone: Conversion rate = (1 - molar amount of 5-methyl-5-methoxy-2(5H)-furanone after reaction / molar amount of 5-methyl-5-methoxy-2(5H)-furanone before reaction) × 100%;

[0127] Calculation method for the yield of methyl acryloylacetate: Yield = molar amount of the target product after reaction / molar amount of 5-methyl-5-methoxy-2(5H)-furanone before reaction × 100%;

[0128] Calculation method for the selectivity of methyl acryloylacetate: Selectivity = yield of the target product / conversion rate of 5-methyl-5-methoxy-2(5H)-furanone × 100%.

[0129] Calculation method for the conversion rate of 5-methylfurfural: Conversion rate = (1 - molar amount of 5-methylfurfural after reaction / molar amount of 5-methylfurfural before reaction) × 100%;

[0130] Calculation method for the yield of methyl acrylate: Yield = molar amount of the target product after reaction / molar amount of 5-methylfurfural before reaction × 100%;

[0131] Selectivity calculation method of acetylacrylic acid: Selectivity = Yield of target product / Conversion rate of 5-methylfurfural × 100%.

[0132] Purity calculation of methyl acetylacrylate: Purity = Peak area of target product / Total peak area of all chromatographic peaks × 100%.

[0133] Table 3

[0134]

[0135]

[0136] As can be seen from the above, the preparation methods of methyl acetylacrylate and acetylacrylic acid in the present invention adopt the methods of photocatalytic oxidation rearrangement and isomerization treatment, which have the advantages of mild experimental conditions, safe products, reduction of environmental pollution and reduction of the use of organic solvents; in addition, the methods are simple and easy to operate, can reduce the loss of target products, and also have a very high yield; and it can be seen from Comparative Example 4 that if the technical solution of the present invention with specific isomerization treatment is not adopted, the yield of acetylacrylic acid will be significantly reduced.

[0137] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for preparing methyl acetylacrylate, characterized in that: The method includes: (1) subjecting 5-methylfurfural to a photocatalytic oxidation reaction in a methanol solvent in an oxygen-containing gas in the presence of an organic photosensitizer to obtain 5-methyl-5-methoxy-2(5H)-furanone; the wavelength of light in the photocatalytic oxidation reaction is 400-800 nm; (2) In the presence of hafnium trifluoromethanesulfonate, the 5-methyl-5-methoxy-2(5H)-furanone is subjected to an isomerization reaction in a solvent 1 to obtain methyl acetylacrylate; the solvent 1 comprises dichloromethane and / or deuterated chloroform.

2. The method according to claim 1, characterized in that In step (2), the isomerization reaction conditions include: temperature of 60-70° C. and time of 24-39 h.

3. The method according to claim 1 or 2, characterized in that: In step (2), the amount of hafnium trifluoromethanesulfonate used is 50-70 g per 1 mol of the 5-methyl-5-methoxy-2(5H)-furanone; And / or, in step (2), the concentration of the 5-methyl-5-methoxy-2(5H)-furanone in the solvent 1 is 0.14-0.17 mol / L.

4. The method according to claim 1 or 2, characterized in that: In step (1), the concentration of 5-methylfurfural in the methanol solvent is 0.03-5 mol / L; And / or, in step (1), the molar amount of the organic photosensitizer is 0.5-5% of the molar amount of the 5-methylfurfural.

5. The method according to claim 1 or 2, characterized in that: The organic photosensitizer is selected from at least one of eosin Y, methylene blue, 9-mesityl-10-methylacridine perchlorate and rhodamine B; And / or, the yield of methyl acetylacrylate is 26.5-47%.

6. The method according to claim 1 or 2, characterized in that: The method described in step (1) further comprises: purifying the mixed solution obtained by the photocatalytic oxidation reaction to obtain the 5-methyl-5-methoxy-2(5H)-furanone; The purification process comprises: (1-1) subjecting the mixed solution to evaporation treatment to obtain a mixed solution 1; the evaporation treatment temperature is 100-150° C.; (1-2) The mixed solution 1 is subjected to distillation treatment, and the fraction obtained during the distillation treatment is the 5-methyl-5-methoxy-2(5H)-furanone; the conditions of the distillation treatment include: a pressure of -0.1Mpa to -0.09Mpa, and a temperature of 200°C to 230°C.

7. Methyl acetylacrylate prepared by the method according to any one of claims 1 to 6; Preferably, the purity of the methyl acetylacrylate is ≥95%.

8. A method for preparing acetyl acrylic acid, characterized in that: The method includes: (S1) subjecting 5-methylfurfural to a photocatalytic oxidation reaction in an acetonitrile solvent in the presence of an organic photosensitizer under an oxygen-containing gas to obtain a solution 1 containing 5-methyl-5-hydroxy-2(5H)-furanone; the wavelength of light in the photocatalytic oxidation reaction is 400-800 nm; (S2) subjecting the solution 1 to an isomerization reaction to obtain acetyl acrylic acid; the isomerization reaction conditions include: a temperature of 40-60° C. and a time of 24-36 hours.

9. The method according to claim 8, characterized in that In step (S1), the concentration of 5-methylfurfural in the acetonitrile solvent is 0.03-5 mol / L; And / or, in step (S1), the molar amount of the organic photosensitizer is 0.5-5% of the molar amount of the 5-methylfurfural.

10. The method according to claim 8 or 9, characterized in that: The organic photosensitizer is selected from at least one of eosin Y, methylene blue, 9-mesityl-10-methylacridine perchlorate and rhodamine B.

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