A method for preparing anisole compounds

Abstract

The application belongs to the field of catalytic material preparation and organic synthesis, and discloses a preparation method of anisole compounds. The application first uses Fe@Ag / TiO2 catalyst to perform selective hydrogenation and deoxidation treatment on syringa alcohol, so that synthesis of anisole compounds is realized. The application uses Fe@Ag / TiO2 catalyst, and does not need reduction treatment, and the selectivity of anisole compounds in the final reaction product is greater than 90%. The reaction temperature is controlled in the range of 473K to 673K, and syringa alcohol can realize hydrogenation reaction, and complete conversion can be realized at the fastest speed at 673K. The catalyst preparation method provided by the application is simple, does not need reduction treatment, has good reaction performance, and has high product selectivity.

Description

Technical Field

[0001] This invention belongs to the field of catalytic material preparation and organic synthesis, and specifically relates to a method for preparing anisole compounds. More particularly, it relates to a method for synthesizing the final product, anisole compound, from syringin alcohol. Background Technology

[0002] Anisole compounds are important intermediates in chemical and pharmaceutical synthesis. They are used as solvents in organic synthesis, as fragrance and organic synthesis intermediates, and are also widely used in the formulation of many floral flavorings, especially gardenia, lilac, and sunflower flavorings. They are also used as antioxidants in beer, UV stabilizers for ethylene polymers, and raw materials for intestinal insecticides.

[0003] 2,6-Dimethoxyphenol, also known as syringol, is a structural monomer formed after lignin cracking and can be obtained through biomass lignin conversion. Lignin is abundant and widely distributed in nature, and can replace petroleum as a raw material for biofuels or chemicals. The use of renewable resources to prepare anisole compounds is a future trend in biomass energy development and has received considerable attention. Heterogeneous or homogeneous catalysis can achieve the important process of hydrodeoxygenation of lignin and its degradation products, and heterogeneous catalysts have been widely used in this field due to their convenient separation and easy regeneration. However, there are currently no reports on the production of anisole through the hydrodeoxygenation of syringol.

[0004] Vo [1] A bimetallic NiMo-supported Al2O3 microsphere catalyst (NiMo@Al2O3) was prepared by combining sol-gel and spray pyrolysis. Then, anatase TiO2 was modified onto the NiMo@Al2O3 shell to prepare a NiMo@Al2O3@TiO2 microsphere catalyst. This catalyst can catalyze the production of methyl-substituted cyclohexane from syringinol (selectivity approximately 87.7%), with the benzene ring, methoxy group, and hydroxyl group in the feedstock being hydrogenated or removed. (Ishikawa et al.) [2]Ru–MnOx / C catalyst was prepared by impregnation method. When syringol was used as the raw material, the selectivity of the main product cyclohexanol was 70%. The benzene ring in the raw material was hydrogenated and the methoxy group was hydrogenated and removed. Guo et al. [3] prepared Ni1Co3Al2-600 (calcined at 600℃) layered catalyst using layered double hydroxide (LDH) Ni1Co3Al2-LDH as the precursor. The main product of HDO reaction using syringol as raw material was also cyclohexanol (selectivity up to 90%). Mukundan et al. [4] anchored Ni metal on MoS2 / C by microemulsion synthesis method. Using syringol as raw material, the selectivity of guaiacol in the product was 25%, followed by phenol and cyclohexanol. It can be found from the above literature that the products of hydrogenation deoxygenation reaction using syringol as raw material are mainly phenol, cyclohexanol or cyclohexane. This not only wastes the function of the methoxy group, but also causes a large amount of hydrogen to be consumed.

[0005] Currently, there are no reports on the use of Fe@Ag / TiO2 as a catalyst for the selective hydrogenation and deoxygenation of syringol to prepare anisole compounds.

[0006] References:

[0007] [1]Vo T K.Bimetallic NiMo-supportedAl2O3@TiO2 core-shell microsphereswithhighhydrodeoxygenation efficiencytowardsyringol[J].JournalofSol-GelScienceandTechnology,2023,105:804-813.

[0008] [2]Ishikawa M, Tamura M, Nakagawa Y, et al. Demethoxylation ofguaiacoland methoxybenzenes over carbon-supportedRu-Mncatalyst[J].AppliedCatalysisB:Environmental,2016,182:193-203.

[0009] [3]Guo D,Cai B,Kang R,etal.Selective hydrodeoxygenation ofguaiacol tocyclohexanol overNixCoyAlz catalystsundermildconditions[J].JournalofAnalyticalandAppliedPyrolysis,2023,170:105876.

[0010] [4]Mukundan S,Atanda L,Beltramini J,et al.Thermocatalytic cleavage ofC-C and CO bonds in model compoundsandkraftligninbyNiMoS2 / Cnanocatalyst[J].SustainableEnergyFuels,2019,3(5):1317-1328. Summary of the Invention

[0011] To overcome the shortcomings of existing technologies, this invention provides a method for preparing anisole compounds. This invention, for the first time, uses a Fe@Ag / TiO2 catalyst to selectively hydrogenate and deoxygenate syringol, achieving the synthesis of the final product, anisole compounds. The catalyst preparation method provided by this invention is simple, requires no reduction treatment, exhibits good reaction performance, and demonstrates high product selectivity.

[0012] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0013] A method for preparing an anisole compound, comprising the following steps:

[0014] S1. Preparation of Fe@Ag / TiO2 catalyst by equal-volume impregnation method:

[0015] (1) To determine the water absorption of TiO2, weigh 1g of dry TiO2 and place it in a beaker. Use a pipette to transfer an appropriate amount of deionized water into the beaker, following the principle of small amounts multiple times, and continuously stir with a glass rod. When the TiO2 in the beaker becomes slightly sticky and no water seeps out, it is the state of TiO2 water absorption saturation. Record the volume of water transferred in as the water absorption; specifically, it is preferably 0.8ml / g.

[0016] (2) Dissolve the Ag-containing compound and the Fe-containing compound in water to prepare Ag solution (such as silver nitrate solution) and Fe solution (such as ferric nitrate solution) with a concentration of 4.0 mol / L. Take the corresponding volume of Ag solution and Fe solution according to the required mmol ratio of catalyst TiO2 to Ag and Fe per gram. Mix the Ag solution and Fe solution to obtain a mixed solution. Add deionized water to make up the liquid volume required for impregnation. The volume is the water absorption measured in step (1). Add TiO2 to the mixed solution and mix evenly. After standing for 2 to 12 hours, dry at 353 K to 383 K for 12 to 24 hours. Then calcine at 623 K to 723 K for 1 to 4 hours in air. Seal and store for later use. Obtain Fe@Ag / TiO2 catalyst.

[0017] S2. Preparation of anisole compounds:

[0018] During the reaction, the catalyst, organic solvent, and syringol were added to a high-temperature and high-pressure batch reactor. After sealing, the air inside the reactor was replaced three times with nitrogen gas at 3.0 MPa. After purging, hydrogen gas at 0.1 MPa to 3.0 MPa was introduced. The reaction temperature range was 473 to 673 K, and the reaction time was 30 min to 12 h. The product was obtained after the reaction.

[0019] The amount of Fe@Ag / TiO2 catalyst used is 5-30% of the mass of syringol.

[0020] In step S2, the organic solvent is any one of n-decane, n-dodecane, and n-tetradecane.

[0021] Furthermore, in step S1, 1g TiO2 is loaded with 0.1-1.0 mmol (0.0108-0.1080g) of Ag and 1.0-2.0 mmol (0.056-0.112g) of Fe.

[0022] Furthermore, in step S1, the Ag-containing compound is silver nitrate; the Fe-containing compound is either ferric nitrate or ferric chloride; and the TiO2 is nano-anatase titanium dioxide with a size between 50-200 mm.

[0023] The advantages of this invention compared to the prior art are:

[0024] This invention utilizes a Fe@Ag / TiO2 catalyst without reduction treatment, achieving a selectivity of over 90% for anisole compounds in the final reaction product. The reaction temperature is controlled between 473 and 673 K, allowing for the hydrogenation of syringol, with 673 K being the optimal temperature for the fastest and most complete conversion. Detailed Implementation

[0025] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0026] The Ag and Fe contents in the catalyst of this invention can be determined by ICP. The range of metal loading on 1g TiO2 is: 0.1-1.0 mmol (0.0108-0.1080 g) of Ag and 1.0-3.0 mmol (0.056-0.168 g) of Fe per 1g TiO2, which yields good reaction performance. During the reaction, the catalyst, organic solvent, and syringol are added to a high-temperature, high-pressure batch reactor. After sealing, the air inside the reactor is replaced three times with 3.0 MPa nitrogen. After purging, hydrogen gas at 0.1 MPa-3.0 MPa is introduced. The reaction temperature range is 473-673 K, and the reaction time is 30 min-12 h. After a period of reaction, samples are taken to calculate the conversion rate of the raw materials and the yield of each product.

[0027]

[0028]

[0029] n0: The amount of syringol in the reaction raw materials (mol);

[0030] n1: The amount of syringol in the reaction solution after the reaction is complete (mol);

[0031] n2: The amount of anisole compound in the reaction solution (mol) after the reaction is complete.

[0032] Since the valence state of the supported metal is not unique after calcination, the loading of Ag and Fe in the catalyst is expressed as the mass ratio of Ag and Fe elements to TiO2. The metal loading is reflected in the "Catalyst Composition" in the example list. For example, 2Fe@0.5Ag / TiO2 means that 1g TiO2 is loaded with 0.5mmol Ag and 2mmol Fe elements.

[0033] Example 1

[0034] A method for preparing an anisole compound, comprising the following steps:

[0035] S1. Preparation of Fe@Ag / TiO2 catalyst by equal-volume impregnation method:

[0036] (1) First, determine the water absorption of TiO2. Weigh 1g of dry TiO2 and place it in a beaker. Use a pipette to transfer an appropriate amount of deionized water into the beaker, following the principle of small amounts multiple times, and continuously stir with a glass rod. When the TiO2 in the beaker becomes slightly sticky and no water seeps out, it is the state of TiO2 water saturation. Record the volume of water transferred in as the water absorption; specifically, 0.8mL.

[0037] (2) Dissolve Ag and Fe compounds separately in water to prepare silver nitrate solution and ferric nitrate solution with concentrations of 4.0 mol / L and 4.0 mol / L, respectively. Mix a certain amount of Ag and Fe solution with deionized water (to make up the liquid volume required for impregnation, i.e., the water absorption determined in step 1). Add 1 g of TiO2 to the solution and stir evenly. After standing for 12 h, dry at 353 K for 12 h and calcine at 673 K for 2 h in air. Seal and store for later use. Obtain Fe@Ag / TiO2 catalyst. The amount of Ag solution added is 0.025 mL; the amount of Fe solution added is 0.5 mL; the catalyst composition is 2Fe@0.1Ag / TiO2.

[0038] S2. Preparation of anisole compounds:

[0039] Before the reaction, 0.05 g of catalyst, 0.5 g of syringol, and 10 ml of n-dodecane were added to a batch reactor. After sealing, the air inside the reactor was replaced three times with nitrogen gas at 3.0 MPa. After purging, hydrogen gas at 3.0 MPa was introduced. The reaction temperature was 573 K, the stirring speed was 700 rpm, and the reaction was carried out for 8 h. The reaction results are shown in Table 1.

[0040] Example 2

[0041] In step (2) of S1, the amount of Ag solution added was 0.075 mL; the amount of Fe solution added was 0.5 mL; and the catalyst composition was 2Fe@0.3Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0042] Example 3

[0043] In step (2) of S1, the amount of Ag solution added was 0.125 mL; the amount of Fe solution added was 0.5 mL; and the catalyst composition was 2Fe@0.5Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0044] Example 4

[0045] In step (2) of S1, the amount of Ag solution added was 0.175 mL; the amount of Fe solution added was 0.5 mL; and the catalyst composition was 2Fe@0.7Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0046] Example 5

[0047] In step (2) of S1, the amount of Ag solution added was 0.25 mL; the amount of Fe solution added was 0.5 mL; and the catalyst composition was 2Fe@1Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0048] Example 6

[0049] In step (2) of S1, the amount of Ag solution added was 0.125 mL; the amount of Fe solution added was 0.25 mL; and the catalyst composition was 1Fe@0.5Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0050] Example 7

[0051] In step (2) of S1, the amount of Ag solution added was 0.125 mL; the amount of Fe solution added was 0.75 mL; and the catalyst composition was 3Fe@0.5Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0052] Example 8

[0053] In step (2) of S1, after standing for 2 hours, it is dried at 353K for 12 hours, and the rest is the same as in Example 3. The reaction results are shown in Table 1.

[0054] Example 9

[0055] In step (2) of S1, after standing for 6 hours, it is dried at 353K for 12 hours, and the rest is the same as in Example 3. The reaction results are shown in Table 1.

[0056] Example 10

[0057] In step (2) of S1, after standing for 12 hours, dry at 373K for 12 hours, and so on, as in Example 3. The reaction results are shown in Table 1.

[0058] Example 11

[0059] In step (2) of S1, after standing for 12 hours, dry at 383K for 12 hours, and so on, as in Example 3. The reaction results are shown in Table 1.

[0060] Example 12

[0061] In step (2) of S1, after standing for 12 hours, it was dried at 383K for 18 hours, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0062] Example 13

[0063] In step (2) of S1, after standing for 12 hours, it was dried at 383K for 24 hours, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0064] Example 14

[0065] In step (2) of S1, the mixture was calcined at 623K for 1 hour in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0066] Example 15

[0067] In step (2) of S1, the mixture was calcined at 623K for 4 hours in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0068] Example 16

[0069] In step (2) of S1, the sample was calcined at 673K ​​for 1 hour in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0070] Example 17

[0071] In step (2) of S1, the sample was calcined at 673K ​​for 4 hours in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0072] Example 18

[0073] In step (2) of S1, the sample was calcined at 723K for 1 hour in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0074] Example 19

[0075] In step (2) of S1, the sample was calcined at 723K for 2 hours in air, and the rest was the same as in Example 3. The reaction results are shown in Table 1.

[0076] Example 20

[0077] In step (2) of S1, Ag and Fe compounds were dissolved in water to prepare silver nitrate solution and ferric chloride solution with concentrations of 4.0 mol / L and 4.0 mol / L, respectively. Other steps were the same as in Example 3. The reaction results are shown in Table 1.

[0078] Example 21

[0079] In step S2, 0.05 g of catalyst, 1 g of syringol, and 15 ml of n-dodecane were added to a batch reactor, and the rest of the reaction was the same as in Example 3. The reaction results are shown in Table 1.

[0080] Example 22

[0081] In step S2, 0.025 g of catalyst, 0.5 g of syringol, and 10 ml of n-dodecane were added to a batch reactor, and the rest of the reaction was the same as in Example 3. The reaction results are shown in Table 1.

[0082] Example 23

[0083] In step S2, 0.10 g of catalyst, 0.5 g of syringol, and 10 ml of n-dodecane were added to a batch reactor, and the rest of the reaction was the same as in Example 3. The reaction results are shown in Table 1.

[0084] Example 24

[0085] In step S2, 0.15 g of catalyst, 0.5 g of syringol, and 10 ml of n-dodecane were added to a batch reactor, and the rest of the reaction was the same as in Example 3. The reaction results are shown in Table 1.

[0086] Example 25

[0087] In step S2, 0.5 g of catalyst, 0.05 g of syringol, and 8 ml of n-dodecane were added to a batch reactor, and the rest of the reaction was the same as in Example 3. The reaction results are shown in Table 1.

[0088] Example 26

[0089] In S2, the reaction temperature was 473 K, the stirring rate was 700 rpm, and the reaction time was 8 h. Other parameters were the same as in Example 3. The reaction results are shown in Table 1.

[0090] Example 27

[0091] In S2, the reaction temperature was 673 K, the stirring rate was 700 rpm, and the reaction time was 8 h. Other procedures were the same as in Example 3. The reaction results are shown in Table 1.

[0092] Example 28

[0093] In S2, the reaction temperature was 573 K, the stirring rate was 700 rpm, and the reaction time was 0.5 h. Other parameters were the same as in Example 3. The reaction results are shown in Table 1.

[0094] Example 29

[0095] In S2, the reaction temperature was 573 K, the stirring rate was 700 rpm, and the reaction time was 4 h. Other procedures were the same as in Example 3. The reaction results are shown in Table 1.

[0096] Example 30

[0097] In S2, the reaction temperature was 573 K, the stirring rate was 700 rpm, and the reaction time was 12 h. Other procedures were the same as in Example 3. The reaction results are shown in Table 1.

[0098] Comparative Example 1

[0099] In step (2) of S1, the amount of Ag solution added was 0 mL; the amount of Fe solution added was 0.5 mL; and the catalyst composition was 2Fe / TiO2. Everything else was the same as in Example 1. The reaction results are shown in Table 1.

[0100] Comparative Example 2

[0101] In step (2) of S1, the amount of Ag solution added was 0.125 mL; the amount of Fe solution added was 0 mL; and the catalyst composition was 0.5 Ag / TiO2. Other steps were the same as in Example 1. The reaction results are shown in Table 1.

[0102] Table 1 Summary of Reaction Results

[0103]

[0104]

[0105] As shown in Table 1, Fe and Ag alone cannot efficiently catalyze the hydrogenation and deoxygenation of syringol. However, their combination and synergistic effect allow the Fe@Ag / TiO2 catalyst to efficiently convert syringol to anisole, resulting in a single final product. Oxygen atoms in the feedstock can be selectively hydrogenated and removed. Increased temperature improves the reaction rate and the distribution of aromatic compounds. After 8 hours of reaction at 673K, syringol is completely converted, and the selectivity for anisole compounds exceeds 90%. Examples 1-7 and Comparative Examples 1-2 demonstrate that the synergistic effect of Ag and Fe effectively improves the conversion rate of syringol and the selectivity for anisole.

[0106] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing anisole compounds, characterized in that, The specific steps are as follows: S1. Preparation of Fe@Ag / TiO2 catalyst by equal-volume impregnation method: (1) To determine the water absorption of TiO2, weigh 1g of dry TiO2 and place it in a beaker. Use a pipette to transfer an appropriate amount of deionized water into the beaker, following the principle of small amounts and multiple times, and continuously stir with a glass rod. When the TiO2 in the beaker becomes slightly sticky and no water seeps out, it is the state of TiO2 water absorption saturation. Record the volume of water transferred in as the water absorption. (2) Dissolve the Ag-containing compound and the Fe-containing compound in water to prepare Ag solution and Fe solution with a concentration of 4.0 mol / L and 4.0 mol / L respectively. Take the corresponding volume of Ag solution and Fe solution according to the required mmol ratio of each gram of catalyst TiO2 to Ag and Fe. Mix the Ag solution and Fe solution to obtain a mixed solution. Add deionized water to make up the liquid volume required for impregnation. The volume is the water absorption measured in step (1). Add TiO2 to the mixed solution and mix evenly. After standing for 2 to 12 hours, dry at 353 K to 383 K for 12 to 24 hours. Then calcine at 623 K to 723 K in air for 1 to 4 hours. Seal and store for later use. Obtain Fe@Ag / TiO2 catalyst. S2. Preparation of anisole compounds: During the reaction, Fe@Ag / TiO2 catalyst, organic solvent and syringol were added to a high-temperature and high-pressure batch reactor. After sealing, the air inside the reactor was replaced three times with nitrogen gas at 3.0 MPa. After purging, hydrogen gas at 0.1 MPa to 3.0 MPa was introduced. The reaction temperature range was 473 to 673 K, and the reaction time was 30 min to 12 h. The product was obtained after the reaction.

2. The method for preparing an anisole compound as described in claim 1, characterized in that, The amount of Fe@Ag / TiO2 catalyst used is 5-30% of the mass of syringol.

3. The method for preparing an anisole compound as described in claim 1, characterized in that, In step S2, the organic solvent is any one of n-decane, n-dodecane, and n-tetradecane.

4. The method for preparing an anisole compound as described in claim 1, characterized in that, step... In S1, 1g TiO2 is loaded with 0.1-1.0 mmol of Ag and 1.0-2.0 mmol of Fe.

5. The method for preparing an anisole compound as described in claim 1, characterized in that, In step S1, the Ag-containing compound is silver nitrate.

6. The method for preparing an anisole compound as described in claim 1, characterized in that, In step S1, the Fe-containing compound is either ferric nitrate or ferric chloride.

7. The method for preparing an anisole compound as described in claim 1, characterized in that, TiO2 is nano-anatase titanium dioxide.

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