Tert-butyl hydroxy anisd and preparation method thereof

Abstract

The invention relates to the technical field of fine chemical engineering, in particular to tert-butyl hydroxy anisd and a preparation method thereof.The method is carried out in a two-phase reaction-extraction coupling system composed of methyl alcohol and n-hexane and comprises the following steps that 1, in the presence of a basic catalyst, tert-butyl hydroquinone and methyl alcohol are subjected to an etherification reaction, and tert-butyl hydroxy anisd is obtained; a reaction mixture containing the tert-butyl hydroxy anisd is generated; 2) carrying out phase separation on the reaction mixture obtained in the step 1) to obtain an n-hexane phase rich in tert-butyl hydroxy anisd as a light phase and a methanol phase rich in unreacted tert-butyl hydroquinone and a catalyst as a heavy phase; and step 3) separating from the n-hexane light phase and purifying to obtain the n-hexane. The method has the advantages that the raw materials are safe, the method is environment-friendly, the operation is simple and convenient, and a novel green synthesis process which is high in conversion rate, high in 3-BHA selectivity and easy in product separation can be realized at the same time.

Description

Technical Field

[0001] This invention relates to the field of fine chemical technology, and in particular to a tert-butylhydroxyanisole and its preparation method. Background Technology

[0002] tert-butylhydroxyanisole (BHA) is a high-performance synthetic phenolic antioxidant. Its commercial products are typically a mixture of two isomers: 3-tert-butyl-4-hydroxyanisole (3-BHA) and 2-tert-butyl-4-hydroxyanisole (2-BHA). Tert-butylhydroxyanisole has the following two isomers: 3-tert-butyl-4-hydroxyanisole (3-BHA) and 2-tert-butyl-4-hydroxyanisole (2-BHA):

[0003]

[0004] BHA's antioxidant effect is 5 times that of butylated hydroxytoluene (BHT). Adding 0.005% to lard can extend the time before it begins to spoil by 4 to 5 times, and adding 0.01% can extend it by 6 times. It can also be used in oils, butter, dried fish and shellfish, salted products, frozen products, and frozen whale meat, with good results. Commercially available BHA antioxidants are mixtures of 3-BHA and 2-BHA, but the antioxidant capacity of 3-BHA is 1.5 to 2 times that of 2-BHA; therefore, a high content of 3-BHA is generally required.

[0005] Currently, the synthetic routes for BHA mainly revolve around the following methods:

[0006] 1) Alkylation of p-hydroxyanisole;

[0007] This method introduces a tert-butyl group from p-hydroxyanisole and tert-butanol or isobutylene under the action of an acid or basic catalyst. The main drawback of this method is the complexity of the reaction process, which generates various alkylated isomers and polyalkylated byproducts, leading to difficulties in separating and purifying the target product, and resulting in unsatisfactory yields and selectivity.

[0008] 2) TBHQ highly toxic methylation reagent method;

[0009] Using tert-butylhydroquinone (TBHQ) as a raw material, it reacts with methylating agents such as dimethyl sulfate or dimethyl carbonate. Dimethyl sulfate is a highly toxic and corrosive chemical, posing a serious challenge to production equipment, operational safety, and environmental protection; while dimethyl carbonate, although a green reagent, suffers from low reactivity and low conversion rate, which restricts its industrial application.

[0010] 3) TBHQ-methanol acid catalytic method;

[0011] The reaction involves TBHQ with methanol under reflux in the presence of an acidic catalyst. While this route offers advantages such as simple reaction steps and high conversion rates, it faces the challenge of complex post-processing of the product. Multiple extractions, washings, and recrystallizations are required to obtain a qualified product, resulting in a long process flow and significant waste generation.

[0012] 4) TBHQ-halomethane base catalysis;

[0013] Under alkaline conditions, TBHQ is etherified with halomethanes (such as chloromethane and iodomethane). The drawback of this route is that halomethanes are highly toxic, and the reaction produces equivalent amounts of halide salts, creating a solid waste treatment problem, which contradicts the current development concept of green chemistry.

[0014] In summary, existing synthetic technologies generally suffer from the following common defects: they either use highly hazardous and toxic raw materials, generate a large number of by-products and waste, have complex and costly product separation and purification processes, or are not satisfactory in controlling the regioselectivity of 3-BHA. Summary of the Invention

[0015] The purpose of this invention is to overcome the shortcomings of the prior art and provide a new green synthesis process for tert-butylhydroxyanisole and its preparation method. This method uses safe raw materials, is environmentally friendly, and is easy to operate. It can simultaneously achieve high conversion rate, high 3-BHA selectivity, and easy product separation.

[0016] This invention is achieved through the following technical solution: On one hand, it provides a method for preparing tert-butylhydroxyanisole, which is carried out in a two-phase reaction-extraction coupled system composed of methanol and n-hexane, and includes the following steps:

[0017] Step 1) In the presence of an alkaline catalyst, tert-butylhydroquinone is etherified with methanol to generate a reaction mixture containing tert-butylhydroxyanisole.

[0018] Step 2) Separate the reaction mixture obtained in Step 1) to obtain a hexane phase rich in tert-butylhydroquinone as the light phase and a methanol phase rich in unreacted tert-butylhydroquinone and catalyst as the heavy phase.

[0019] Step 3) Separate and purify the n-hexane light phase to obtain the final product.

[0020] Through the above technical solution, this invention uses TBHQ and methanol as raw materials, methanol as the first-phase solvent, n-hexane as the second-phase solvent, and an alkaline substance as a catalyst. It can be used in various reaction devices such as batch reactor, continuous reactor, fluidized bed, fixed bed, and microchannel reactors. Utilizing the different solubilities of the raw material TBHQ and the product BHA in the methanol and n-hexane phases, most of the generated BHA dissolves in the n-hexane phase, while most of the raw material TBHQ dissolves in the methanol phase. The by-product water and the salt-forming effect of TBHQ with the alkaline catalyst further enhance the polarity of the methanol phase, making the separation of TBHQ and BHA more thorough, thereby promoting the forward reaction. After the reaction, cooling and phase separation can separate most of the residual raw material TBHQ and BHA. The heavy phase (methanol phase) is distilled under negative pressure to remove water, and the recovered methanol is mixed with the distillation vessel residue for reuse. The light phase (n-hexane phase) is distilled under negative pressure to recover n-hexane (containing a small amount of methanol), and then BHA is obtained by negative pressure distillation.

[0021] Further, in step 1), the mass ratio of tert-butylhydroquinone to methanol is 1:0.58 to 0.96; the mass ratio of tert-butylhydroquinone to n-hexane is 1:5 to 10.

[0022] Through the above technical solution, the product BHA and the raw material TBHQ can be rapidly separated in the methanol-n-hexane two-phase reaction-extraction coupling system. Most of BHA is in the n-hexane phase, and most of the raw material TBHQ is in the methanol phase, thereby promoting the forward reaction.

[0023] Further, in step 1), the temperature of the etherification reaction is 120℃~180℃, and the reaction time is 4h~16h.

[0024] The above technical solution allows the etherification reaction to proceed under sufficient temperature conditions, ensuring a relatively complete reaction.

[0025] Further, in step 1), the alkaline catalyst is selected from one or more of inorganic strong bases, organic strong bases, or solid base catalysts; wherein,

[0026] The inorganic strong base is selected from sodium hydroxide and potassium hydroxide;

[0027] The organic strong base is any one of sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, and triethylamine; the solid base catalyst is selected from one of supported strong bases, hydrotalcite-based catalysts, and composite solid bases.

[0028] Furthermore, when the alkaline catalyst is an inorganic strong base or an organic strong base, its molar ratio with tert-butylhydroquinone is 0.05:1 to 0.1:1;

[0029] When the alkaline catalyst is a solid alkaline catalyst, its dosage is 10% to 20% of the mass of tert-butylhydroquinone.

[0030] Through the above technical solution, this process uses a solid base catalyst. Compared with the catalyst dissolved in the reaction system, the solid base can achieve rapid separation from the reaction liquid, making it convenient for recycling.

[0031] Further, in step 1), the etherification reaction is carried out in a reaction apparatus selected from the group consisting of: batch reactor, continuous reactor, fluidized bed reactor, fixed bed reactor or microchannel reactor;

[0032] Among them, when using inorganic strong base or organic strong base catalysts, the reaction is carried out in batch reactor, continuous reactor, fluidized bed reactor or microchannel reactor;

[0033] When using a solid base catalyst, the reaction is carried out in a batch reactor, a continuous reactor, a fluidized bed reactor, or a fixed bed reactor.

[0034] Furthermore, for batch reactors, tert-butylhydroquinone, methanol, alkaline catalyst, and n-hexane are fed in at once;

[0035] For continuous batch reaction, a mixture of raw materials formed by premixing tert-butylhydroquinone, methanol and alkaline catalyst is continuously pumped into the reaction system in proportion to n-hexane;

[0036] When the reaction is carried out continuously in a fixed-bed reactor or a microchannel reactor with a catalyst sintering layer, the mass hourly space velocity (MSV) based on tert-butylhydroquinone is 0.1 h⁻¹. - 1~1.0h - 1.

[0037] Through the above technical solutions, fixed-bed reactors or microchannel reactors with catalyst sintering layers can greatly improve reaction stability and production efficiency.

[0038] Furthermore, the method also includes the processing and application of the methanol heavy phase obtained in step 2):

[0039] After the methanol heavy phase is devolatilized, the methanol, unreacted tert-butylhydroquinone, and alkaline catalyst contained therein can be recycled; wherein, when an inorganic strong base or an organic strong base catalyst is used, the conversion rate of tert-butylhydroquinone is not lower than that of the first round of reaction.

[0040] Furthermore, when using the catalyst, fresh alkaline catalyst is added as a supplement, with the amount added being 1% to 10% of the mass of the catalyst added in the first round.

[0041] The above technical solution allows for the reuse of methanol, n-hexane, unreacted tert-butylhydroquinone, and catalysts, thereby reducing process costs.

[0042] Another tert-butylhydroxyanisole is provided, which is prepared by the above method; the conversion rate of tert-butylhydroquinone is ≥90%; the total selectivity of the obtained tert-butylhydroxyanisole is ≥95%; and the purity of the obtained tert-butylhydroxyanisole is above 98%.

[0043] Beneficial effects

[0044] This invention features a simple process flow, mild reaction conditions, and applicability to various reaction devices such as batch reactors, continuous reactors, fluidized beds, fixed beds, and microchannels. It also offers convenient separation and purification, high production efficiency, and is particularly suitable for industrial production. The TBHQ single-pass conversion rate of this invention can reach over 90%, the 3-BHA selectivity can reach over 85%, and the purity of the separated and purified BHA product can reach over 98%. Attached Figure Description

[0045] Figure 1 This is a process flow diagram illustrating the batch reactor process of this invention;

[0046] Figure 2 This is a process flow diagram illustrating the continuous reaction in a fixed bed, as described in this invention.

[0047] Figure 1 In the diagram, 1-Premix tank; 2-Stirred reactor; 3-Precision filter; 4-Phase separation tank; 5-Light phase tank; 6-Distillation column A; 7-Condenser A; 8-Recovered n-hexane tank; 9-Product tank; 10-Heavy component temporary storage tank; 11-Heavy phase tank; 12-Distillation column B; 13-Condenser B; 14-Recovered methanol tank; 15-Water tank; 16-Fixed bed reactor. Detailed Implementation

[0048] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0049] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer. Unless otherwise stated, all percentages, ratios, proportions, or parts are by weight.

[0050] Unless otherwise specified, the reagents and raw materials used in the embodiments and comparative examples of this invention are commercially available.

[0051] The raw material TBHQ has a purity of ≥98.0% and was purchased from Ron Reagents. The solid base catalyst was purchased from Jiangyin Nanda Synthetic Chemical Co., Ltd., Qinzhou Yamei Chemical Co., Ltd., and Hydrotalcite (Shandong) Technology Development Co., Ltd.

[0052] External standard method detection conditions for liquid chromatography: Instrument: Thermo Fisher U3000; Detector: UV detector; Column: C18 (250mm*4.6mm, 5μm); Detection wavelength: 353nm; Mobile phase:

[0053] H2O / CH3OH = 15 / 85, after 15 min, switch to pure methanol, and stop the injection after 30 min; flow rate: 1.0 ml / min; injection volume: 4 μL, the concentration range of the external standard curve should be prepared as needed.

[0054] Gas chromatograph area normalization method detection conditions: Instrument: Agilent 8860; Detector: FID; Column: HP-5; Vaporization chamber temperature: 180℃; Detector temperature: 180℃; Column oven temperature: initial temperature 50℃, hold for 5 min, heating rate 10℃ / min, final temperature 150℃, hold for 1 min; Injection volume: 0.4 μL; Carrier gas (N2) flow rate: 2.0 ml / min; Air flow rate: 300 ml / min; Hydrogen flow rate: 30 ml / min.

[0055] Example 1

[0056] 100.00 g (0.6 mol) of TBHQ, 57.83 g (1.8 mol) of methanol, and 1.63 g (0.03 mol) of sodium methoxide were weighed and added sequentially to the reactor. 500 g of n-hexane was then weighed and added. The reactor was sealed, and high-purity nitrogen gas (0.5 MPa) was introduced four times to purge excess nitrogen. Stirring was started, and after 10 minutes of stirring, heating was initiated. The mixture was heated to 150°C and maintained at this temperature for a certain period, followed by stirring to lower the temperature. After cooling to room temperature, the mixture was separated into liquids, revealing a clear stratification interface. The light and heavy phases were weighed and sampled separately. Samples were taken at 4 h, 7 h, 10 h, 13 h, and 16 h of reaction time to determine the content of TBHQ, 2-BHA, and 3-BHA. The conversion rate of TBHQ and the selectivity of BHA were calculated.

[0057] Calculation formula:

[0058]

[0059] Note: TBHQ, 3-BHA, and 2-BHA in both the light and heavy phases were detected using external standard method in liquid chromatography. The results are summarized below:

[0060]

[0061] As shown in the table above, the optimal reaction time is 10 hours. Longer reaction times tend to produce more tar and reduce reaction selectivity.

[0062] Examples 2-5

[0063] Sodium hydroxide, potassium hydroxide, potassium methoxide, sodium ethoxide, and triethylamine were used as catalysts, respectively. The operation steps and molar ratios were the same as in Example 1, and the reaction time was 10 h.

[0064] The reaction results are as follows:

[0065] Example catalyst TBHQ conversion rate 3-BHA selectivity BHA total selectivity Example 1 Sodium methoxide 93.67％ 85.39％ 96.42％ Example 2 Sodium hydroxide 91.35％ 85.64％ 95.77％ Example 3 potassium hydroxide 93.15％ 86.27％ 96.31％ Example 4 Potassium methoxide 94.41％ 86.32％ 95.65％ Example 5 Sodium ethoxide 90.21％ 83.10％ 92.67％ Example 6 Triethylamine 44.53％ 63.77％ 87.36％

[0066] As shown in the table above, sodium methoxide, sodium hydroxide, potassium hydroxide, and potassium methoxide all exhibit good catalytic performance, with TBHQ conversion exceeding 90%, 3-BHA selectivity exceeding 85%, and total BHA selectivity exceeding 95%.

[0067] Examples 7-9

[0068] HND-64 solid superalkali produced by Jiangyin Nanda Synthetic Chemical Co., Ltd., potassium fluoride / activated alumina solid alkali catalyst produced by Qinzhou Yamei Chemical Co., Ltd., and aluminum-magnesium hydrotalcite produced by hydrotalcite (Shandong) Technology Development Co., Ltd. were used as catalysts for the reaction. The amount of catalyst added was 15% of the mass of TBHQ. Other feed ratios and process parameters were the same as in Example 1. The reaction was carried out in a batch reactor (see process flow chart). Figure 1 The reaction time was 10 hours, and these were recorded as Examples 5, 6, and 7, respectively. After the reaction was completed, the mixture was cooled and filtered. Subsequent operations were the same as in Example 1.

[0069] The reaction results are summarized below:

[0070] Example catalyst TBHQ conversion rate 3-BHA selectivity BHA total selectivity Example 7 HND-64 94.41％ 82.22％ 95.74％ Example 8 <![CDATA[KF / Al2O3]]> 90.03％ 78.36％ 93.27％ Example 9 Aluminum-magnesium hydrotalcite 76.82％ 63.96％ 90.45％

[0071] As shown in the table above, HND-64 exhibits good response results.

[0072] Example 10

[0073] HND-64 solid superbase, produced by Jiangyin Nanda Synthetic Chemical Co., Ltd., was used as a fixed-bed catalyst. The catalyst was tableted using a 30MPa tablet press, crushed, and then sieved through a 10-12 mesh standard sieve before being packed into a fixed-bed reactor with an inner diameter of 2cm and a length of 60cm (process flow is available in [link]). Figure 2 The catalyst loading is 54g. TBHQ and methanol are mixed uniformly at a molar ratio of 1:3 and a mass ratio of TBHQ to n-hexane of 1:5. The mass hourly space velocity (WHSV) for TBHQ is 0.2h. -1The reaction temperature was 150℃. The mixed raw materials were pumped into the reactor using a high-pressure metering pump. After cooling, the reaction solution entered a collection tank. Samples were taken and tested every 2 hours. Some results are summarized below:

[0074]

[0075]

[0076] As shown in the table above, the color of the reaction solution darkened significantly after continuous operation for more than 40 hours, and the catalyst performance decreased significantly after more than 52 hours. After cooling and unloading the catalyst, it was found to be dark brown, with some parts in a viscous state, indicating that the tar coating caused the catalyst activity to decrease.

[0077] Comparative Example

[0078] Except for the absence of hexane, the conditions were the same as in Example 1.

[0079] Results: The reaction system was a homogeneous phase, and separation was not possible after the reaction; dilution with water and extraction were required, making the operation complex. The TBHQ conversion rate was 89.45%, but the overall selectivity for BHA was only 90.11%, and the reaction mixture was dark in color with a significant increase in tar-like byproducts.

[0080] Effect Example

[0081] To verify the reusability of the catalysts, representative inorganic / organic strong base and solid base catalysts were selected. The inorganic / organic strong base catalysts were derived from the heavy components of methanol phase distillation. The heavy phase (methanol phase) was distilled off by separating methanol and water sequentially under slight negative pressure; the residue in the distillation vessel was the catalyst to be used. Solid base catalysts could be directly reused through filtration, with the amount of fresh catalyst added being 5% of the initial batch mass.

[0082] like Figure 1 The batch reactor process shown is used to process a mixture of methanol, TBHQ, and n-hexane, with the addition of a catalyst (Gat). Liquid or methanol- or hexane-soluble catalysts are added via pipeline, while solid acid catalysts are added via hopper. The steps are as follows:

[0083] Step 1: Raw material premixing; Methanol, TBHQ and n-hexane are transported to premixing tank 1 in proportion through pipeline and mixed. TBHQ is melted at 140℃ and the pipeline is heated and kept warm. Catalysts that are soluble in methanol or n-hexane can be added by dissolving a small amount of methanol or n-hexane and then transporting it through pipeline. Catalysts that cannot be dissolved, such as solid alkali, can be added to batch reactor 2 in one go through the hopper.

[0084] Step 2: Etherification reaction; the mixture is transferred to reactor 2, and a solid alkali catalyst is added for intermittent reaction. After nitrogen purging, stirring and heat source are turned on to heat to the reaction temperature. After a certain reaction time, the heat source is turned off and the coolant is turned on to cool down to 30±5℃.

[0085] Step 3: Solid-liquid separation; After the reaction is completed, for batch reactions using solid base catalysts, the reaction mixture is filtered through precision filter 3 to remove the solid catalyst. Dissolved catalysts do not need to go through this step and the reaction liquid is directly pumped into phase separation tank 4.

[0086] Step 4: Phase separation; After filtration, the mixture enters phase separation tank 4 and is allowed to stand and separate into light and heavy phases. The light phase is the n-hexane phase, and the heavy phase is the methanol phase.

[0087] Step 5: Light phase (n-hexane phase) treatment; The light phase enters the light phase tank 5, and is then pumped to distillation column A 6. In distillation column A 6, the components are separated; The vapor at the top of the column is condensed by condenser A 7, and the recovered n-hexane enters the n-hexane recovery tank 8. This step is operated at atmospheric pressure or slightly negative pressure. Specific parameters can be obtained experimentally or calculated by technicians. After the n-hexane recovery is completed, the product is distilled. The product is distilled under high vacuum. First, the unqualified fore-fraction is distilled off, and then the product is obtained. The product enters the product tank 9, and the heavy components enter the heavy component temporary storage tank 10. Specific parameters can be obtained experimentally or calculated by technicians.

[0088] The distilled heavy components can be reused multiple times. Once the total amount of active ingredients (BHA and TBHQ) is less than 30%, it is treated as waste liquid and sent to a qualified unit for disposal.

[0089] Step 6: Heavy Phase (Methanol Phase) Treatment; The heavy phase enters the heavy phase tank 11 from the phase separation tank 4, and is then pumped to the distillation column B 12. In the distillation column B 12, the top vapor is condensed by the condenser B 13, and the recovered methanol enters the methanol recovery tank 14. Water is then distilled off, and the distilled water enters the water tank 15, which is then treated as wastewater. This step is carried out under a slight negative pressure condition. Specific parameters can be obtained experimentally or calculated by technicians. The residue in the distillation kettle mainly consists of catalyst (or its salt with THBQ), unreacted TBHQ, a small amount of BHA, and tar. The recovered methanol is pumped back to the distillation column, and the residue in the distillation kettle is washed out and reused in the next reaction vessel.

[0090] like Figure 2 The fixed-bed continuous reaction shown can be achieved by those skilled in the art using conventional technical means, based on the above scheme.

[0091] Based on the above scheme, the first batch reaction used fresh raw materials TBHQ, methanol, n-hexane, and catalyst. The results of the subsequent batch reaction with multiple reuses of the catalyst are as follows:

[0092]

[0093] As shown in the table above, both potassium hydroxide and potassium methoxide exhibit good reusability. Since the raw material TBHQ and the alkaline catalyst already form a salt, TBHQ is no longer consumed, thus improving the conversion rate of TBHQ. After four reusable cycles, the activity of the HND-64 solid alkaline catalyst significantly decreased. The reason for this decrease is still the formation of tar coating the catalyst. Soaking and washing the tar with acetone can restore most of the activity.

[0094] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing tert-butylhydroxyanisole, characterized in that, This method is carried out in a two-phase reaction-extraction coupled system consisting of methanol and n-hexane, and includes the following steps: Step 1) In the presence of an alkaline catalyst, tert-butylhydroquinone is etherified with methanol to generate a reaction mixture containing tert-butylhydroxyanisole. Step 2) Separate the reaction mixture obtained in Step 1) to obtain a hexane phase rich in tert-butylhydroquinone as the light phase and a methanol phase rich in unreacted tert-butylhydroquinone and catalyst as the heavy phase. Step 3) Separate and purify the n-hexane light phase to obtain the final product.

2. The method for preparing tert-butylhydroxyanisole according to claim 1, characterized in that, In step 1), the mass ratio of tert-butylhydroquinone to methanol is 1:0.58 to 0.96; the mass ratio of tert-butylhydroquinone to n-hexane is 1:5 to 10.

3. The method for preparing tert-butylhydroxyanisole according to claim 1, characterized in that, In step 1), the etherification reaction is carried out at a temperature of 120°C to 180°C for 4 hours to 16 hours.

4. The method for preparing tert-butylhydroxyanisole according to claim 1, characterized in that, In step 1), the alkaline catalyst is selected from one or more of inorganic strong bases, organic strong bases, or solid base catalysts; wherein, The inorganic strong base is selected from sodium hydroxide and potassium hydroxide; The organic strong base is any one of sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, and triethylamine; the solid base catalyst is selected from one of supported strong bases, hydrotalcite-based catalysts, and composite solid bases.

5. The method for preparing tert-butylhydroxyanisole according to claim 4, characterized in that, When the alkaline catalyst is an inorganic strong base or an organic strong base, its molar ratio with tert-butylhydroquinone is 0.05:1 to 0.1:

1. When the alkaline catalyst is a solid alkaline catalyst, its dosage is 10% to 20% of the mass of tert-butylhydroquinone.

6. The method for preparing tert-butylhydroxyanisole according to claim 1, characterized in that, In step 1), the etherification reaction is carried out in a reaction apparatus selected from the group consisting of: batch reactor, continuous reactor, fluidized bed reactor, fixed bed reactor or microchannel reactor; Among them, when using inorganic strong base or organic strong base catalysts, the reaction is carried out in batch reactor, continuous reactor, fluidized bed reactor or microchannel reactor; When using a solid base catalyst, the reaction is carried out in a batch reactor, a continuous reactor, a fluidized bed reactor, or a fixed bed reactor.

7. The method for preparing tert-butylhydroxyanisole according to claim 6, characterized in that, For batch reactors, tert-butylhydroquinone, methanol, alkaline catalyst, and n-hexane are fed in at once. For continuous batch reaction, a mixture of raw materials formed by premixing tert-butylhydroquinone, methanol and alkaline catalyst is continuously pumped into the reaction system in proportion to n-hexane; When the reaction is carried out continuously in a fixed-bed reactor or a microchannel reactor with a catalyst sintering layer, the mass hourly space velocity (MSV) based on tert-butylhydroquinone is 0.1 h⁻¹. - 1~1.0h - 1.

8. The method for preparing tert-butylhydroxyanisole according to claim 1, characterized in that, The method also includes the processing and application of the methanol heavy phase obtained in step 2): After the methanol heavy phase is devolatilized, the methanol, unreacted tert-butylhydroquinone, and alkaline catalyst contained therein can be recycled; wherein, when an inorganic strong base or an organic strong base catalyst is used, the conversion rate of tert-butylhydroquinone is not lower than that of the first round of reaction.

9. The method for preparing tert-butylhydroxyanisole according to claim 8, characterized in that, When using catalysts, fresh alkaline catalyst should be added as a supplement, with the amount added being 1% to 10% of the mass of the catalyst added in the first round.

10. A tert-butylhydroxyanisole, characterized in that, It is prepared by the method according to any one of claims 1-9; the conversion rate of the tert-butylhydroquinone is ≥90%; the total selectivity of the obtained tert-butylhydroxyanisole is ≥95%; and the purity of the obtained tert-butylhydroxyanisole is ≥98%.

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