A kind of preparation method of 3-methylphenethyl ether

Abstract

The present invention relates to a method for preparing 3-methylphenethyl ether, the method comprising the following steps: under the action of a catalyst, catalyzing m-methylphenol and ethanol to generate 3-methylphenethyl ether, wherein the catalyst is a silver-tin-zinc composite nitrogen silicon compound. The yield of the present invention is as high as more than 90%, and can be continuously and stably operated for 3000h. The process has high carbon atom utilization rate, adopts a continuous fixed bed process, has high reaction efficiency, does not need to use other solvents, and has low separation cost. And ethanol cost is low, and the overall process cost is greatly reduced. In addition, the reaction steps are simple, synthesis is achieved in one step, has good reactivity and selectivity, can achieve long-term stable operation, and is an ideal process for industrial production.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a process for preparing 3-methylphenethyl ether by reacting m-methylphenol with ethanol. Background Art

[0002] 3-Methylphenetole, also known as m-methylphenetole, is an important chemical intermediate that can be used to synthesize compounds such as Benzenemethanol, 3-ethoxy-, 1-benzoate, Benzoic acid, 3,4,5-trimethoxy-, (3-ethoxyphenyl) methyl ester, and Benzenemethanol, 3-ethoxy-, 1-(2-nitrobenzoate). There are a variety of synthesis schemes for this compound in the prior art. Ahmad proposed (Synthetic Communications: An International Journal for Rapid Communication of Synthetic Organic Chemistry) a two-step synthesis process. In the first step, sodium ethoxide is reacted with m-cresol to obtain sodium 3-methylphenolate; in the second step, sodium 3-methylphenolate is reacted with diethyl carbonate in an N,N-dimethylacetamide solvent system at 137°C for 46h to obtain 3-methylphenetole. The reaction produces ethanol and carbon dioxide as byproducts, with an overall yield of 73%. Overall, the process has low carbon atom utilization, produces carbon dioxide, has a long reaction time, has low production efficiency, and needs to remove N,N-dimethylacetamide and ethanol after the reaction, resulting in high energy consumption.

[0003] Ahmad R.Massah (Synthetic Communicationsw, 37:1807–1815, 2007) proposed to use m-cresol and diethyl sulfate in a molar ratio of 1:1.5 at 60°C for 4.5 hours, and the yield of 3-methylphenyl ether was 88%. However, potassium carbonate and sodium bicarbonate were added as substrates in the reaction, which made subsequent separation very difficult. In addition, diethyl sulfate is highly toxic and is listed in the list of Class 2A carcinogens, which poses a great safety risk to personnel during production and operation.

[0004] Jumbam (Molecules 2019, 24, 3720) used boron trifluoride ether complex to react with m-cresol and reflux overnight to produce 3-methylphenethyl ether, boron trifluoride and ethanol, with a yield of 3-methylphenethyl ether of 90%. Although this process can be achieved in one step, the boron trifluoride ether complex needs to be specially customized, which is expensive and not suitable for industrialization.

[0005] As can be seen from the above, the existing processes have great disadvantages and are difficult to achieve industrial production. How to develop a simple, efficient, low-cost and safe process is an urgent research direction in the future. Summary of the invention

[0006] The object of the present invention is to provide a method for preparing 3-methylphenethyl ether, wherein a novel catalyst is used to catalyze the generation of m-methylphenol and ethanol to obtain 3-methylphenethyl ether. The process has high carbon atom utilization rate, adopts a continuous fixed bed process, has high reaction efficiency, does not need to use other solvents, and has low separation cost. The ethanol cost is low, and the overall process cost is greatly reduced. In addition, the reaction steps are simple, the synthesis is achieved in one step, has good reactivity and selectivity, can achieve long-term stable operation, and is an ideal process for industrial production.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A method for producing 3-methylphenethyl ether comprises the following steps: catalyzing m-methylphenol and ethanol to generate 3-methylphenethyl ether under the action of a catalyst, wherein the catalyst is a silver-tin-zinc composite nitrogen silicon compound.

[0009] In a preferred embodiment, in the catalyst of the present invention, the molar ratio of silver element to tin element is 5.5-14.2, and the molar ratio of silver element to zinc element is 4.0-20.6.

[0010] In a preferred embodiment, the catalytic reaction of m-cresol and ethanol is carried out in a fixed bed; preferably, the amount of m-cresol added is 30-80% of the total mass of m-cresol and ethanol.

[0011] In a preferred embodiment, the reaction temperature of m-cresol and ethanol is 240-320° C., and the reaction pressure is 0.1-2.5 bar(G).

[0012] In a preferred embodiment, the liquid hourly mass space velocity of m-cresol is 0.1-0.8h -1 .

[0013] In a preferred embodiment, the method for preparing the silver-tin-zinc composite nitrogen silicide catalyst comprises the following steps:

[0014] (1) placing a silver source, a tin source, a zinc source, an alkali source and an ionic liquid in a certain proportion into a polytetrafluoroethylene crystallization kettle, and placing them in a sealed state at a certain temperature for a period of time;

[0015] (2) filtering and washing the liquid after the reaction until it is neutral, and drying;

[0016] (3) placing the dried solid in an air atmosphere, heating it to a certain temperature and maintaining it for a period of time;

[0017] (4) mixing the calcined solid with a certain amount of silica gel and drying;

[0018] (5) placing the solid dried in step (4) in an ammonia atmosphere, heating it to a certain temperature and maintaining it for a period of time, and finally obtaining a catalyst.

[0019] Wherein, in the step (1), the mass ratio of the silver source to the tin source is 5-10, the mass ratio of the silver source to the zinc source is 3-7, the mass ratio of the silver source to the alkali source is 20-40, and the mass ratio of the silver source to the ionic liquid is 30-60.

[0020] The silver source of the present invention is one or more of silver acetate and silver nitrate.

[0021] The tin source of the present invention is one or more of tin tetrachloride, stannous oxalate and stannous sulfate.

[0022] The zinc source of the present invention is one or more of zinc nitrate hexahydrate, zinc chloride and zinc sulfate.

[0023] The alkali source of the present invention is one of sodium hydroxide, potassium hydroxide and rubidium hydroxide hydrate.

[0024] The ionic liquid of the present invention is one or more of hexafluoroantimonate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium tetrafluoroborate.

[0025] In step (1) of the present invention, the crystallization is carried out in a sealed polytetrafluoroethylene reactor at 170-230° C. for 12-72 hours.

[0026] Wherein, in the step (3), the heating temperature is 350-600°C and the heating time is 4-12h.

[0027] Wherein, in the step (4), the amount of silica gel added accounts for 5-20% of the mass of the solid after calcination.

[0028] Wherein, in the step (5), the heating temperature is 300-600° C. and the heating time is 4-12 h.

[0029] The larger groups of ionic liquids can effectively disperse metals, forming more uniform active sites and more easily forming highly active sites with single-atom structures. Silver-zinc-tin loaded on nitrogen-silicon compounds will form active sites of Ag-O-Zn-O-Sn composite structure after calcination, which can effectively adsorb and activate m-methylphenol and ethanol, catalyzing their reactions. DETAILED DESCRIPTION

[0030] In order to better understand the technical solution of the present invention, the following examples will further illustrate the method provided by the present invention, but the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the claims of the present invention.

[0031] The present invention is further described below with reference to the embodiments, but does not constitute any limitation.

[0032] Reactor used in the embodiment: The reaction adopts a fixed bed reactor made of 316L material, the inner diameter of the reaction tube is 20mm, and 316L distillation filler is loaded at both ends of the catalyst. The composition of the m-methylphenol-ethanol reaction solution is analyzed by gas chromatography, and the operating conditions are: Shimadzu GC-2030 gas chromatograph, GL C18-H 5um4.6X50mm chromatographic column, N, N-dimethylformamide as dilution solvent. The vaporization chamber temperature is 320°C, the column flow rate is 0.8.00mL / min, and the injection volume is 0.3μL. The chromatographic column is programmed to heat: first, the temperature is increased from 40°C to 160°C at a heating rate of 3°C / min, and finally the temperature is increased to 270°C at a heating rate of 5°C / min.

[0033] The raw materials in the examples are shown in Table 1.

[0034] Table 1 Source of raw materials

[0035]

[0036]

[0037] Embodiment 1:

[0038] The preparation method of the catalyst is as follows:

[0039] (1) silver acetate, stannous sulfate, zinc chloride, potassium hydroxide and hexafluoroantimonate are placed in a polytetrafluoroethylene crystallization reactor in a certain ratio, and placed in a sealed state at 210° C. for 14 hours, wherein the mass ratio of silver acetate to stannous sulfate is 6, the mass ratio of silver acetate to zinc chloride is 4, the mass ratio of silver acetate to potassium hydroxide is 22, and the mass ratio of silver acetate to hexafluoroantimonate is 58;

[0040] (2) filtering and washing the liquid after the reaction until it is neutral, and drying it at 120° C. for 12 h;

[0041] (3) placing the dried solid in an air atmosphere, heating to 450°C and maintaining for 6 hours;

[0042] (4) The calcined solid silica gel is mixed evenly, the amount of silica sol added is 18% of the calcined solid, and dried at 120° C. for 12 h;

[0043] (5) The solid dried in step (4) was placed in an ammonia atmosphere, heated to 350° C. and maintained for 11 h to finally obtain a catalyst.

[0044] The reaction conditions of m-cresol and ethanol are as follows:

[0045] The catalytic reaction of m-cresol and ethanol was carried out in a fixed bed. The amount of m-cresol added was 40% of the total mass of m-cresol and ethanol. The reaction temperature was 250°C, the reaction pressure was 0.8 bar(G), and the liquid hourly mass space velocity of m-cresol was 0.2 h -1 .

[0046] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0047] Embodiment 2:

[0048] The preparation method of the catalyst is as follows:

[0049] (1) silver nitrate, tin tetrachloride, zinc nitrate hexahydrate, sodium hydroxide and 1-butyl-3-methylimidazolium tetrafluoroborate are placed in a polytetrafluoroethylene crystallization reactor in a certain ratio, and placed in a sealed state at 180° C. for 68 hours, wherein the mass ratio of silver nitrate to tin tetrachloride is 8, the mass ratio of silver nitrate to zinc nitrate hexahydrate is 6, the mass ratio of silver nitrate to sodium hydroxide is 38, and the mass ratio of silver nitrate to 1-butyl-3-methylimidazolium tetrafluoroborate is 46;

[0050] (2) filtering and washing the liquid after the reaction until it is neutral, and drying it at 120° C. for 12 h;

[0051] (3) placing the dried solid in an air atmosphere, heating to 350°C and maintaining for 8 hours;

[0052] (4) The calcined solid silica gel was mixed evenly, with the amount of silica sol added accounting for 16% of the calcined solid, and dried at 120° C. for 12 h;

[0053] (5) The solid dried in step (4) is placed in an ammonia atmosphere, heated to 580° C. and maintained for 8 h to finally obtain a catalyst.

[0054] The reaction conditions of m-cresol and ethanol are as follows:

[0055] The catalytic reaction of m-cresol and ethanol was carried out in a fixed bed. The amount of m-cresol added was 70% of the total mass of m-cresol and ethanol. The reaction temperature was 280°C, the reaction pressure was 0.4 bar(G), and the liquid hourly mass space velocity of m-cresol was 0.4 h -1 .

[0056] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0057] Embodiment 3:

[0058] The preparation method of the catalyst is as follows:

[0059] (1) silver nitrate, stannous oxalate, zinc sulfate, rubidium hydroxide hydrate and 1-butyl-3-methylimidazolium tetrafluoroborate are placed in a polytetrafluoroethylene crystallization reactor in a certain ratio, and placed in a sealed state at 190° C. for 50 hours, wherein the mass ratio of silver nitrate to stannous oxalate is 7, the mass ratio of silver nitrate to zinc sulfate is 5, the mass ratio of silver nitrate to rubidium hydroxide hydrate is 26, and the mass ratio of silver nitrate to 1-butyl-3-methylimidazolium tetrafluoroborate is 39;

[0060] (2) filtering and washing the liquid after the reaction until it is neutral, and drying it at 120° C. for 12 h;

[0061] (3) placing the dried solid in an air atmosphere, heating to 400°C and maintaining for 10 hours;

[0062] (4) mixing the calcined solid silica gel evenly, with the amount of silica sol added accounting for 50% of the calcined solid, and drying at 120° C. for 12 h;

[0063] (5) The solid dried in step (4) is placed in an ammonia atmosphere, heated to 520° C. and maintained for 7 h to finally obtain a catalyst.

[0064] The reaction conditions of m-cresol and ethanol are as follows:

[0065] The catalytic reaction of m-cresol and ethanol was carried out in a fixed bed. The amount of m-cresol added was 50% of the total mass of m-cresol and ethanol. The reaction temperature was 310°C, the reaction pressure was 2.1 bar(G), and the liquid hourly mass space velocity of m-cresol was 0.7 h -1 .

[0066] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0067] Embodiment 4:

[0068] The preparation method of the catalyst is as follows:

[0069] (1) silver acetate, stannous sulfate, zinc nitrate hexahydrate, sodium hydroxide and 1-butyl-3-methylimidazolium hexafluorophosphate are placed in a polytetrafluoroethylene crystallization reactor in a certain ratio, and placed in a sealed state at 220° C. for 35 hours, wherein the mass ratio of silver acetate to stannous sulfate is 9, the mass ratio of silver acetate to zinc nitrate hexahydrate is 7, the mass ratio of silver acetate to sodium hydroxide is 31, and the mass ratio of silver acetate to 1-butyl-3-methylimidazolium hexafluorophosphate is 49;

[0070] (2) filtering and washing the liquid after the reaction until it is neutral, and drying it at 120° C. for 12 h;

[0071] (3) placing the dried solid in an air atmosphere, heating to 550°C and maintaining for 12 hours;

[0072] (4) The calcined solid silica gel is mixed evenly, the amount of silica sol added is 12% of the calcined solid, and dried at 120° C. for 12 h;

[0073] (5) The solid dried in step (4) is placed in an ammonia atmosphere, heated to 410° C. and maintained for 5 h to finally obtain a catalyst.

[0074] The reaction conditions of m-cresol and ethanol are as follows:

[0075] The catalytic reaction of m-cresol and ethanol was carried out in a fixed bed. The amount of m-cresol added was 60% of the total mass of m-cresol and ethanol. The reaction temperature was 290°C, the reaction pressure was 1.5 bar(G), and the liquid hourly mass space velocity of m-cresol was 0.5 h -1 .

[0076] After the reaction is stable, samples are taken and the results are analyzed by gas chromatography. The specific results of the embodiment are shown in Table 1.

[0077] The catalyst prepared in Example 3 was used for life test. The specific reaction steps were the same as those in Example 3. After running for 3000 hours, the conversion rate was 92% and the selectivity was 96.4%. The activity and selectivity did not decrease significantly.

[0078] Comparative Example 1:

[0079] The preparation method of the catalyst is basically the same as that of Example 1, the only difference being that the ionic liquid hexafluoroantimonate is not added.

[0080] The reaction conditions of m-cresol and ethanol are the same as those in Example 1.

[0081] Comparative Example 2:

[0082] The preparation method of the catalyst is substantially the same as that of Example 1, the only difference being that silver acetate is not added.

[0083] The reaction conditions of m-cresol and ethanol are the same as those in Example 1.

[0084] Comparative Example 3:

[0085] The preparation method of the catalyst is substantially the same as that of Example 1, the only difference being that stannous sulfate is not added.

[0086] The reaction conditions of m-cresol and ethanol are the same as those in Example 1.

[0087] Comparative Example 4:

[0088] The preparation method of the catalyst is basically the same as that of Example 1, the only difference being that zinc chloride is not added.

[0089] The reaction conditions of m-cresol and ethanol are the same as those in Example 1.

[0090] Table 2 Conversion rate and selectivity of each example

[0091] Serial number Meta-cresol conversion rate % 3-Methylphenethyl ether selectivity % Example 1 93 98 Example 2 91 99 Example 3 97 97 Example 4 94 99 Comparative Example 1 54 79 Comparative Example 2 37 72 Comparative Example 3 41 81 Comparative Example 4 29 64

[0092] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for preparing 3-methylphenethyl ether, comprising catalyzing m-methylphenol and ethanol to generate 3-methylphenethyl ether under the action of a catalyst, wherein: The catalyst is a silver-tin-zinc composite nitrogen-silicon compound; the catalyst preparation method comprises the following steps: (1) placing a silver source, a tin source, a zinc source, an alkali source and an ionic liquid in a certain proportion into a polytetrafluoroethylene crystallization kettle, and placing them in a sealed state at a certain temperature for a period of time; (2) filtering and washing the liquid after the reaction until it is neutral, and drying; (3) placing the dried solid in an air atmosphere, heating it to a certain temperature and maintaining it for a period of time; (4) mixing the calcined solid with a certain amount of silica gel and drying; placing the dried solid in step (4) under an ammonia atmosphere, heating to a certain temperature and maintaining it for a period of time, and finally obtaining a catalyst; The ionic liquid is one or more of hexafluoroantimonate, 1-butyl-3-methylimidazolium hexafluorophosphate and 1-butyl-3-methylimidazolium tetrafluoroborate.

2. The method according to claim 1, characterized in that In the catalyst, the molar ratio of silver element to tin element is 5.5-14.2, and the molar ratio of silver element to zinc element is 4.0-20.

6.

3. The method according to claim 1, characterized in that The catalytic reaction of m-cresol and ethanol is carried out in a fixed bed; the added amount of m-cresol is 30-80% of the total mass of m-cresol and ethanol.

4. The method according to claim 1, characterized in that The reaction temperature of m-cresol and ethanol is 240-320°C, and the reaction pressure is 0.1-2.5 barG.

5. The method according to claim 1, characterized in that The liquid hourly mass space velocity of m-cresol is 0.1-0.8h -1 .

6. The method according to claim 1, characterized in that In the step (1), the mass ratio of the silver source to the tin source is 5-10, the mass ratio of the silver source to the zinc source is 3-7, the mass ratio of the silver source to the alkali source is 20-40, and the mass ratio of the silver source to the ionic liquid is 30-60.

7. The method according to claim 1, characterized in that The silver source is one or more of silver acetate and silver nitrate; the tin source is one or more of tin tetrachloride, stannous oxalate and stannous sulfate; the zinc source is one or more of zinc nitrate hexahydrate, zinc chloride and zinc sulfate.

8. The method according to claim 1, characterized in that In the step (4), the amount of silica gel added is 5-20% of the mass of the solid after calcination.

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