Method for producing m-ethyl anisole and p-ethyl anisole from xylenol oil

Abstract

The invention belongs to the technical field of coal coking and production and separation of organic chemical products, and particularly relates to a method for producing m-ethyl anisole and p-ethyl anisole from xylenol oil. According to the method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil, provided by the invention, a mixture containing 2, 3-dimethyl anisole / m-p-ethyl anisole / 3, 5-dimethyl anisole is obtained through etherification reaction and rectification treatment; and sequentially adding a sulfuric acid solution and isobutene to react, and carrying out rectification and other steps to prepare ethyl anisole and p-ethyl anisole. The raw material used in the method is the low-price xylenol phenol oil fraction, the production cost is low, the reaction conditions are mild, only etherates are generated in the reaction process, side reactions of alkylation and dealkylation on benzene rings are basically avoided, and pure products of m-ethyl anisole and p-ethyl anisole are obtained through reaction with isobutene, rectification, tert-butyl removal and rectification.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal coking and production and separation of organic chemical products, and particularly relates to a method for producing m-ethylanisole and p-ethylanisole from xylenol phenol oil. Background Art

[0002] Fractionation or rectification of phenol-containing coal tar can obtain a xylenol phenol oil fraction (208-222 °C) rich in 2,4 / 2,5-xylenol, m / p-ethylphenol, 3,5-xylenol, and 2,3-xylenol. The contents of m-cresol, p-cresol, and o-ethylphenol are relatively small. Direct rectification of the xylenol phenol oil fraction cannot achieve the separation of phenol and phenol oil. Extraction with an alkaline substance gives a mixture of xylenols. In the mixture, the contents of m / p-ethylphenol and 3,5-xylenol are high, and the contents of 2,3-xylenol and 2,4 / 2,5-xylenol are secondary. Their boiling points are 218 °C, 219 °C, 217 °C, and 211 °C respectively, with a small difference in boiling points. The relative volatility of 2,3-xylenol is high, and only partial separation of m / p-ethylphenol / 3,5-xylenol and 2,3-xylenol can be achieved in a high-efficiency rectification tower, and the resulting product is still a mixture.

[0003] When the xylenol phenol oil fraction is hydrogenated to produce gasoline and diesel, the presence of phenolic materials will consume a large amount of hydrogen, resulting in too high hydrogen consumption and a large increase in production costs. A large amount of water is generated in the hydrogenation reaction, which will cause the loss and agglomeration of the hydrogenation catalyst, seriously affecting the catalyst life and easily leading to production failures. Therefore, xylenols in the phenol oil need to be extracted before hydrogenation of the xylenol phenol oil fraction. The commonly used method is to extract xylenols in the phenol oil with alkaline water, then neutralize with sulfuric acid, and let it stand for stratification to obtain a cresol mixture containing 10% water, and a large amount of high-salt wastewater containing phenol and sodium sulfate is generated. This method has now been clearly phased out. In addition, the solvent extraction method currently under development is to extract xylenols in the xylenol phenol oil with an alcoholamine solvent. This method has many steps and high operating costs, and there is no very successful industrial application in China at present.

[0004] m-Ethylanisole, also known as 3-ethylanisole, with the English name 3-ethylanisole, is an important chemical intermediate and can be used to synthesize various substances such as m-methoxyacetophenone, 2-ethyl-3-methoxyacetophenone, and 2-ethyl-3-bromoanisole. The current synthesis method is to react m-ethylphenol with a methylation reagent to produce m-ethylanisole, and the methylation reagent includes methyl iodide and dimethyl sulfate.

[0005] CN117820088A discloses a preparation method of m-ethylanisole, in which methanol and m-ethylphenol are introduced into Ti supported on BiO 2 -CeO 2The catalyst on the composite support is used to prepare m-ethyl anisole by reaction. The conversion rate of m-ethyl phenol is high, and the selectivity of m-ethyl anisole is high. It can operate continuously and stably for 3000 h. The raw material used in the method of this invention is expensive m-ethyl phenol (price: 80,000 - 100,000 yuan / ton), and an efficient composite catalyst is developed. Using a continuous fixed-bed process, the selectivity of m-ethoxy anisole is high, and the yield of m-ethyl anisole can reach 97%.

[0006] Therefore, how to prepare m-ethyl anisole and p-ethyl anisole using the inexpensive xylenol fraction has received increasing attention. Summary of the Invention

[0007] This invention is made based on the inventor's discovery and understanding of the following facts and problems:

[0008] m-ethyl anisole, p-ethyl anisole, 2,4-dimethyl anisole, etc. are important organic synthesis intermediates, which are often prepared from expensive m-ethyl phenol, p-ethyl phenol, and 2,4-xylenol. However, the xylenol fraction cannot extract m / p-ethyl phenol, 2,4-xylenol, o-isopropyl phenol, etc. through rectification, and it is even more impossible to produce directly pure m-ethyl phenol, p-ethyl phenol, 2,4-xylenol, 2,5-xylenol, o-isopropyl phenol, etc. These products are often only sold at a low price or disposed of as waste without being reasonably utilized.

[0009] The methods of the prior art can only ensure high etherification selectivity at low mixed phenol conversion rates or with high-temperature efficient catalysts. The yield is low, the energy consumption is high, and the production cost is very high. Moreover, they are aimed at mixed xylenol or pure xylenol, mainly pure xylenol. Most of the products synthesized and extracted from mixed xylenol are mixtures of phenolic ethers, and the separation of m / p-ethyl anisole is not carried out. It is very difficult, almost impossible, to separate the etherified products by rectification to produce m-ethyl anisole and p-ethyl anisole. Therefore, the prior art is difficult to be popularized and applied industrially, and the cost is relatively high.

[0010] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, an embodiment of the present invention provides a method for producing m-ethyl anisole and p-ethyl anisole from xylenol fraction. By reacting an alkaline catalyst, an etherification reagent with the xylenol fraction, the boiling points of various dimethyl benzyl ethers or ethyl benzyl ethers obtained are significantly lower than those of the de-phenolized oil. Thus, various dimethyl benzyl ethers and various ethyl benzyl ethers of phenolic derivatives can be separated from the phenolic oil in the xylenol fraction by layering or direct rectification, and the de-phenolized oil is sent for hydrogenation, reducing the production cost.

[0011] The method for producing m-ethyl anisole and p-ethyl anisole from xylenol fraction according to the embodiment of the present invention is characterized by including the following steps:

[0012] (1) Mix the xylenol phenolic oil fraction and the aqueous alkali solution, let it stand and separate into layers to obtain the de-phenol phenolic oil layer and the water layer. First, heat up and reflux to distill out the neutral oil in the water layer, then add an alkylating agent to the water layer for etherification reaction. After the reaction, let it stand to obtain a material layer and a water layer. The material layer is washed to obtain a feed layer; the phenolic substances in the xylenol phenolic oil fraction include: 2,4-xylenol 0.1 - 30 wt%, 2,5-xylenol 0.1 - 20 wt%, m / p-ethylphenol 30 - 100 wt%, 3,4-xylenol 0.1 - 50 wt%, 2,3-xylenol 0.1 - 30 wt%, 3,5-xylenol 0.1 - 50 wt%, o-isopropylphenol 0.1 - 20 wt%.

[0013] (2) Carry out rectification treatment on the feed layer to obtain a 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture, a 2,3-dimethylanisole / m / p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture, an o-isopropylanisole / 3,4-dimethylanisole mixture, and rectification still residue 1.

[0014] (3) Add concentrated sulfuric acid solution to the 2,3-dimethylanisole / m / p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture obtained in step (2), introduce isobutene. After the reaction ends, add an alkali solution to neutralize, let it stand to obtain a material layer. The material layer is rectified under reduced pressure to successively obtain diisobutene, 3,5-dimethylanisole, a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture, a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture, 4,6-di-tert-butyl-2,3-dimethylanisole, a 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole mixture, and still residue 4,6-di-tert-butyl-3-ethylanisole.

[0015] (4) Carry out rectification treatment on the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture to obtain a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture and 4,6-di-tert-butyl-2,3-dimethylanisole.

[0016] (5) Add concentrated sulfuric acid solution to the 2,6 - di - tert - butyl - 4 - ethyl anisole / 4,6 - di - tert - butyl - 2 - isopropyl anisole mixture obtained in step (3) or step (4) for reaction. After the reaction, neutralize with an alkaline solution, separate the layers, and subject the obtained material layer to vacuum distillation to successively obtain 99% p - ethyl anisole, a p - ethyl anisole / o - isopropyl anisole mixture, and o - isopropyl anisole;

[0017] (6) Add concentrated sulfuric acid solution to the residue 4,6 - di - tert - butyl - 3 - ethyl anisole obtained in step (3) for reaction. After the reaction, neutralize with an alkaline solution, separate the layers of the obtained material layer, and subject the material layer to vacuum distillation to obtain m - ethyl anisole.

[0018] The advantages and technical effects brought by the method for producing m - ethyl anisole and p - ethyl anisole from xylenol phenolic oil in the embodiments of the present invention are as follows: 1. In the method of the embodiments of the present invention, an alkaline aqueous solution is used to extract the xylenol phenolic oil fraction to obtain the upper - layer phenol - removed phenolic oil and the aqueous layer of sodium phenolate solution. After heating, impurities such as neutral oil in the sodium phenolate aqueous solution can be removed, and then an etherification reaction is carried out with an alkylating agent to obtain water - insoluble dimethylbenzene alkyl ethers, ethylbenzene alkyl ethers, etc. The separated material layer can be distilled to obtain mixtures or pure substances of various specific dimethylbenzene alkyl ethers and ethylbenzene alkyl ethers, which is convenient for subsequent separation by tert - butylation to obtain various dimethylbenzene alkyl ethers and ethylbenzene alkyl ethers; 2. In the method of the embodiments of the present invention, a basic catalyst and an etherification reagent are used to react with the xylenol phenolic oil fraction. The boiling points of substances such as dimethylbenzyl ether obtained are significantly lower than those of the corresponding xylenols (the melting points also decrease). Thus, xylenols (which have formed ether compounds) can be separated from the phenolic oil in the xylenol phenolic oil fraction by layer separation or direct distillation, and at the same time, preliminary separation of various dimethylbenzene alkyl ethers is achieved. The phenolic oil after phenol removal is sent for hydrogenation, reducing the production cost; 3. In the method of the embodiments of the present invention, the boiling points of substances such as dimethylbenzene alkyl ethers obtained are lower than the boiling points of the corresponding xylenols (the melting points also decrease significantly). During distillation, the energy consumption is reduced, and there will be no problem that the materials are easily blocked in the pipeline during distillation. The operation is convenient, and the production cost is also reduced; 4. In the method of the embodiments of the present invention, the relatively inexpensive xylenol phenolic oil fraction is used, and the production cost of m - ethyl anisole and p - ethyl anisole is low, with very considerable economic benefits and good market competitiveness; 5. In the method of the embodiments of the present invention, the reaction conditions are mild. During the reaction, only ether compounds are formed, and basically no side reactions such as alkylation and dealkylation on the benzene ring occur. Then, through reaction with isobutene, distillation, de - tert - butylation, and distillation, pure products of m - ethyl anisole and p - ethyl anisole are obtained. The conversion rates of various xylenols and ethylphenols in the reaction can be controlled above 98%; 6. In the method of the embodiments of the present invention, the process has good operability and strong usability, with significant economic benefits, and is convenient for popularization and application in industrial production.

[0019] In some embodiments, in step (1), the method for preparing the xylenol phenol oil fraction includes: adding phenol-containing coal tar into the bottom of a rectification column, first removing water under normal pressure, and then performing vacuum rectification to successively obtain a light oil fraction below 170 °C, a phenol oil fraction of 170 - 230 °C, a cresol fraction of 230 - 240 °C, a catechol fraction of 240 - 250 °C, a 5-indanol fraction of 250 - 270 °C, and a resorcinol / hydroquinone fraction of 270 - 300 °C; wherein the phenol oil fraction of 170 - 230 °C is further rectified to obtain a xylenol phenol oil fraction of 209 - 222 °C;

[0020] And / or, in step (1), the aqueous alkali solution includes at least one of an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution;

[0021] And / or, in step (1), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkali is 1:1 - 3;

[0022] And / or, in step (1), the xylenol phenol oil fraction and the aqueous alkali solution are mixed, first heated and stirred and then allowed to stand and separate layers. The temperature for heating and stirring is 30 - 80 °C, and the time for heating and stirring is 0.5 - 2 h;

[0023] And / or, in step (1), the temperature for heating and refluxing is 105 - 110 °C, and the time for heating and refluxing is 0.5 - 2 h;

[0024] And / or, in step (1), the alkylating agent includes at least one of an iodoalkane, a chloroalkane, a dialkyl sulfate, or a dialkyl carbonate;

[0025] And / or, in step (1), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkylating agent is 1:0.5 - 5;

[0026] And / or, in step (1), the temperature of the etherification reaction is 0 - 150 °C, the time of the etherification reaction is 4 - 20 h, and the pressure required for the etherification reaction is 0 - 1 MPa;

[0027] And / or, in step (1), after the etherification reaction, standing and separating layers are carried out at 70 - 90 °C;

[0028] And / or, in step (1), the washing includes: adding a sulfuric acid solution to the material layer and washing for 0.5 - 2 h, then separating layers, washing the obtained material layer with water, and separating layers to remove the washing water;

[0029] And / or, in step (2), the pressure for the rectification treatment is -0.05 - 0.1 MPa, and the reflux ratio is 15 - 25:1;

[0030] And / or, in the step (2), the residue 1 in the rectification still mainly contains 3,4-dimethylanisole, and 3,4-dimethylanisole is obtained after rectifying the residue 1 in the rectification still;

[0031] And / or, in the step (3), the mass of the concentrated sulfuric acid solution is 1-5% of the mass of the 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture;

[0032] And / or, in the step (3), the temperature for introducing isobutene for reaction is 60-120 °C, and after the reaction, an alkali solution is added to neutralize to pH 7-8;

[0033] And / or, in the step (3), the mass of the isobutene is 1-3 times the mass of the 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture;

[0034] And / or, in the step (3), after introducing isobutene for reaction, sampling and analysis are carried out, and when the content of 6-tert-butyl-3-ethylanisole ≤ 0.5%, it indicates that the reaction is completed;

[0035] And / or, in the step (5), the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture;

[0036] And / or, in the step (5), the temperature of the reaction is 180-200 °C, the reaction time is 1-3 h, sampling and analysis are carried out, and when the content of 2-tert-butyl-4-ethylanisole ≤ 0.5%, it indicates that the reaction is completed, and after the reaction, an alkali solution is added to neutralize to pH 7-8;

[0037] And / or, in the step (6), the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of 4,6-di-tert-butyl-3-ethylanisole;

[0038] And / or, in the step (6), the temperature of the reaction is 180-200 °C, the reaction time is 1-3 h, sampling and analysis are carried out, and when the content of 6-tert-butyl-3-ethylanisole ≤ 0.5%, it indicates that the reaction is completed, and after the reaction, an alkali solution is added to neutralize to pH 7-8.

[0039] In some embodiments, in the step (2), the separation of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture includes the following steps:

[0040] S1. Add the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture and the concentrated sulfuric acid solution into a reactor, and while stirring, heat up to 60-120 °C and introduce isobutene for reaction;

[0041] S2. After the reaction is completed, an alkali solution is added to neutralize the pH to 7 - 8. After separating the aqueous layer, the material layer is rectified to obtain diisobutylene, 6-tert-butyl-2,4-dimethylanisole, intermediate fraction 1, 4-tert-butyl-2,5-dimethylanisole, intermediate fraction 2, and still residue 2; the intermediate fraction 1 is a mixture of 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole, the intermediate fraction 2 is a mixture of 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole, and the still residue 2 is 4,6-di-tert-butyl-2,3-dimethylanisole;

[0042] S3. The intermediate fraction 1 is rectified to obtain 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole; the intermediate fraction 2 is rectified to obtain 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole;

[0043] S4. Deisobutenylation of tert-butylated products: Concentrated sulfuric acid solution is added to 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole, and 4,6-di-tert-butyl-2,3-dimethylanisole respectively for deisobutenylation reaction. After the reaction is completed, an alkali solution is added to neutralize to pH 7 - 8. After liquid separation, the obtained material layer is rectified to obtain 2,4-dimethylanisole, 2,5-dimethylanisole, and 2,3-dimethylanisole.

[0044] In some embodiments, in S1, the mass of the concentrated sulfuric acid solution is 1 - 5% of the mass of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture;

[0045] And / or, in S1, the mass of isobutene is 1 - 3 times the mass of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture;

[0046] And / or, in S1, after introducing isobutene for reaction, sampling and analysis show that when 6-tert-butyl-2,3-xylenol ≤ 0.5%, the reaction is completed;

[0047] And / or, in S2, the reflux ratio of the rectification is 10 - 25:1;

[0048] And / or, in S4, the mass of the concentrated sulfuric acid solution is 0.5 - 3% of the mass of 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole, and 4,6-di-tert-butyl-2,3-dimethylanisole respectively;

[0049] And / or, in S4, the temperature of the isobutene removal reaction is 180 to 200 °C, and the time of the isobutene removal reaction is 1 to 3 h.

[0050] In some embodiments, in step (2), the separation method of the o-isopropyl anisole / 3,4-dimethyl anisole mixture comprises the following steps:

[0051] (a) Add concentrated sulfuric acid solution to the o-isopropyl anisole / 3,4-dimethyl anisole mixture, stir and heat up to 60 to 120 °C, introduce isobutene for reaction, after the reaction is completed, add alkali solution to neutralize to pH 7 to 8, separate the layers, and subject the obtained material layer to vacuum distillation to obtain 6-tert-butyl-3,4-dimethyl anisole, and the residue in the kettle is 4,6-di-tert-butyl-2-isopropyl anisole, and recycle the recovered isobutene;

[0052] (b) Deisobutenylation of tert-butylated products: Add concentrated sulfuric acid solution to 6-tert-butyl-3,4-dimethyl anisole and 4,6-di-tert-butyl-2-isopropyl anisole respectively for deisobutenylation reaction. After the reaction is completed, cool down and then add alkali solution to neutralize to pH 7 to 8. After separating the layers, subject the material layer to vacuum distillation to obtain 3,4-dimethyl anisole and 99% o-isopropyl anisole, and recycle the recovered isobutene.

[0053] In some embodiments, in step (a), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of the o-isopropyl anisole / 3,4-dimethyl anisole mixture;

[0054] And / or, in step (a), the mass of the isobutene is 1 to 3 times the mass of the o-isopropyl anisole / 3,4-dimethyl anisole mixture;

[0055] And / or, in step (a), after introducing the isobutene for reaction, sample and analyze. When the content of 6-tert-butyl-2-isopropyl anisole ≤ 0.5%, it indicates that the reaction is completed;

[0056] And / or, in step (b), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of 6-tert-butyl-3,4-dimethyl anisole and 4,6-di-tert-butyl-2-isopropyl anisole respectively;

[0057] And / or, in step (b), the temperature of the isobutene removal reaction is 180 to 200 °C, and the time of the isobutene removal reaction is 1 to 3 h.

[0058] In some embodiments, step (3) further comprises: subjecting the 4,6-di-tert-butyl-2,3-dimethyl anisole / 4,6-di-tert-butyl-3-ethyl anisole mixture to rectification treatment to obtain 4,6-di-tert-butyl-2,3-dimethyl anisole;

[0059] Concentrated sulfuric acid solution was added to 4,6 - di - tert - butyl - 2,3 - dimethylanisole, and the mixture was stirred and heated to 180 - 200 °C for reaction for 1 - 3 hours. Then, an alkaline solution was added to neutralize it to pH 7 - 8, and after stratification, the obtained material layer was subjected to vacuum distillation to successively obtain 2,3 - dimethylanisole;

[0060] Preferably, the mass of the concentrated sulfuric acid solution is 0.5 - 3% of the mass of 4,6 - di - tert - butyl - 2,3 - dimethylanisole;

[0061] During the reaction process, samples were taken for analysis. When the content of 6 - tert - butyl - 2,3 - dimethylanisole ≤ 0.5%, it indicates the end of the reaction.

[0062] The method for producing m - ethylanisole and p - ethylanisole from xylenol phenol oil provided in the embodiments of the present invention may further include the following steps:

[0063] (A) The xylenol phenol oil fraction and an aqueous alkaline solution were mixed, and after standing and stratifying, a dephenolized phenol oil layer and a water layer were obtained. First, the neutral oil in the water layer was distilled off by heating under reflux, and then an alkylating agent was added to the water layer for etherification reaction. After the reaction, it was left standing to obtain a material layer and a water layer. The material layer was washed to obtain a feed layer; the composition of phenolic substances in the xylenol phenol oil fraction includes: 30 - 100 wt% of m - p - ethylphenol, 0.1 - 30 wt% of 2,3 - xylenol, and 0.1 - 50 wt% of 3,5 - xylenol;

[0064] (B) The feed layer was subjected to rectification treatment to obtain a mixture of 2,3 - dimethylanisole / m - p - ethylanisole / 3,5 - dimethylanisole and still residue;

[0065] (C) Concentrated sulfuric acid was added to the mixture of 2,3 - dimethylanisole / m - p - ethylanisole / 3,5 - dimethylanisole obtained in step (B), and then isobutene was introduced for reaction. Then, an alkaline solution was introduced for neutralization. After separating the water layer, the feed layer was subjected to vacuum distillation to successively obtain diisobutene, 3,5 - dimethylanisole, 2,6 - di - tert - butyl - 4 - ethylanisole, a mixture of 2,6 - di - tert - butyl - 4 - ethylanisole / 4,6 - di - tert - butyl - 2,3 - dimethylanisole, 4,6 - di - tert - butyl - 2,3 - dimethylanisole, a mixture of 4,6 - di - tert - butyl - 2,3 - dimethylanisole / 4,6 - di - tert - butyl - 3 - ethylanisole, and still residue 4,6 - di - tert - butyl - 3 - ethylanisole; the mixture of 2,6 - di - tert - butyl - 4 - ethylanisole / 4,6 - di - tert - butyl - 2,3 - dimethylanisole was rectified to obtain 2,6 - di - tert - butyl - 4 - ethylanisole and 4,6 - di - tert - butyl - 2,3 - dimethylanisole; the mixture of 4,6 - di - tert - butyl - 2,3 - dimethylanisole / 4,6 - di - tert - butyl - 3 - ethylanisole was rectified to obtain 4,6 - di - tert - butyl - 2,3 - dimethylanisole;

[0066] (D) Concentrated sulfuric acid is added to 2,6 - di - tert - butyl - 4 - ethyl anisole. After the reaction, an alkali solution is added for neutralization and layering treatment. The obtained material layer is subjected to vacuum distillation to obtain p - ethyl anisole;

[0067] (E) Concentrated sulfuric acid is added to 4,6 - di - tert - butyl - 3 - ethyl anisole. After the reaction, an alkali solution is added for neutralization and layering treatment. The obtained material layer is subjected to vacuum distillation to obtain m - ethyl anisole.

[0068] In some embodiments, in the step (A), the preparation method of the xylenol phenol oil fraction includes: adding phenol - containing coal tar into the bottom of the distillation column, first removing water under atmospheric pressure, and then performing vacuum distillation to successively obtain a light oil fraction below 170 °C, a phenol oil fraction at 170 - 230 °C, a cresol fraction at 230 - 240 °C, a catechol fraction at 240 - 250 °C, a 5 - indanol fraction at 250 - 270 °C, and a resorcinol / hydroquinone fraction at 270 - 300 °C; among which, the phenol oil fraction at 170 - 230 °C is further distilled to obtain a xylenol phenol oil fraction at 209 - 222 °C;

[0069] And / or, in the step (A), the aqueous alkali solution includes at least one of an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution;

[0070] And / or, in the step (A), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkali is 1:1 - 3;

[0071] And / or, in the step (A), the xylenol phenol oil fraction and the aqueous alkali solution are mixed, first heated and stirred and then allowed to stand for layering. The temperature of the heating and stirring is 30 - 80 °C, and the time of heating and stirring is 0.5 - 2 h;

[0072] And / or, in the step (A), the temperature of the heating and refluxing is 105 - 110 °C, and the time of heating and refluxing is 0.5 - 2 h;

[0073] And / or, in the step (A), the alkylating agent includes at least one of iodoalkanes, chloroalkanes, dialkyl sulfates, or dialkyl carbonates;

[0074] And / or, in the step (A), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkylating agent is 1:0.5 - 5;

[0075] And / or, in the step (A), the temperature of the etherification reaction is 0 - 150 °C, the time of the etherification reaction is 4 - 20 h, and the pressure required for the etherification reaction is 0 - 1 MPa;

[0076] And / or, in the step (A), after the etherification reaction, standing for layering is carried out at 70 - 90 °C;

[0077] And / or, in the step (A), the washing includes: adding a sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, then separating the layers, washing the obtained material layer with water, and separating the layers to remove the washing water;

[0078] And / or, in the step (B), the pressure of the rectification treatment is -0.05 to 0.1 MPa, the reflux ratio of the rectification treatment is 20 to 25:1, the bottom residue is a mixture of 2,3-dimethylanisole / m - p - ethylanisole / 3,5-dimethylanisole and other inevitable impurities, and the bottom residue is used for rectification to obtain a mixture of 2,3-dimethylanisole / m - p - ethylanisole / 3,5-dimethylanisole;

[0079] And / or, in the step (C), the dosage of the concentrated sulfuric acid is 1 to 5% of the mass of the mixture of 2,3-dimethylanisole / m - p - ethylanisole / 3,5-dimethylanisole, and the mass of the isobutene is 1 to 3 times the mass of the mixed m - p - methylanisole;

[0080] And / or, in the step (C), the reaction temperature for introducing the isobutene is 60 to 120 °C; introducing an alkali solution to neutralize the pH to 7 to 8, and the reflux ratio of the vacuum rectification is 15 to 30:1;

[0081] And / or, further includes the step (F), adding concentrated sulfuric acid to 4,6 - di - tert - butyl - 2,3 - dimethylanisole, reacting, then adding an alkali solution for neutralization and separation treatment, and subjecting the obtained material layer to vacuum rectification to obtain 2,3 - dimethylanisole.

[0082] The embodiment of the present invention also provides a synthesis of xylenol:

[0083] Mix any one of the prepared p - ethylanisole, 2,5 - dimethylanisole, 3,4 - dimethylanisole, 3,5 - dimethylanisole, o - isopropylbenzene, or any one of the prepared p - ethylanisole, 3,5 - dimethylanisole, 2,3 - dimethylanisole and mesitylene, heat up to 130 to 150 °C, dropwise add 45 to 55% hydrobromic acid and react for 4 to 6 hours. The generated bromomethane gas is cooled to -10 °C by a condenser and a two - stage cold trap and enters the bromoalkane storage tank. After the reaction is completed, stop collecting the bromoalkane, collect the generated bromomethane, then slightly cool the reaction solution and separate out the aqueous hydrobromic acid solution. Wash the solvent layer once and separate the layers. Combine the water layers to obtain a recovered hydrobromic acid solution. Send the hydrobromic acid solution to other sections for concentration to recover 47% hydrobromic acid. Subject the material layer to vacuum rectification to obtain xylenol, and recycle the mesitylene for reuse;

[0084] Preferably, the mesitylene includes at least one of 1,2,3 - trimethylbenzene, 1,2,4 - trimethylbenzene, and 1,3,5 - trimethylbenzene;

[0085] And / or, the dosage of the mesitylene is 1 to 3 times the mass of the m-ethylanisole or p-ethylanisole;

[0086] And / or, the molar ratio of hydrogen bromide to m-ethylanisole or p-ethylanisole in the hydrobromic acid is 1 to 3. Specific embodiments

[0087] The embodiments of the present invention will be described in detail below. The embodiments are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0088] A method for producing m-ethylanisole and p-ethylanisole from xylenol phenol oil in an embodiment of the present invention is characterized by comprising the following steps:

[0089] (1) Mix the xylenol phenol oil fraction and the aqueous alkali solution, stand and layer to obtain a de-phenol phenol oil layer and a water layer. First, heat up and reflux to distill out the neutral oil in the water layer, and then add an alkylating agent to the water layer for etherification reaction. After the reaction, stand and layer to obtain a material layer and a water layer. The material layer is washed to obtain a feed layer; the phenolic substances in the xylenol phenol oil fraction include: 0.1 to 30 wt% of 2,4-xylenol, 0.1 to 20 wt% of 2,5-xylenol, 30 to 100 wt% of m,p-ethylphenol, 0.1 to 50 wt% of 3,4-xylenol, 0.1 to 30 wt% of 2,3-xylenol, 0.1 to 50 wt% of 3,5-xylenol, and 0.1 to 20 wt% of o-isopropylphenol;

[0090] (2) Subject the feed layer to rectification treatment to obtain a 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture, a 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture, an o-isopropylanisole / 3,4-dimethylanisole mixture, and rectification still residue 1;

[0091] (3) Add concentrated sulfuric acid solution to the 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture obtained in step (2), introduce isobutene, after the reaction, neutralize with an alkali solution, stand to obtain a material layer, and subject the material layer to vacuum rectification to obtain diisobutene, 3,5-dimethylanisole, a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture, a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture, 4,6-di-tert-butyl-2,3-dimethylanisole, a 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole mixture, and still residue 4,6-di-tert-butyl-3-ethylanisole;

[0092] (4) The mixture of 2,6-di-tert-butyl-4-ethyl anisole / 4,6-di-tert-butyl-2-isopropyl anisole / 4,6-di-tert-butyl-2,3-dimethyl anisole is subjected to rectification to obtain a mixture of 2,6-di-tert-butyl-4-ethyl anisole / 4,6-di-tert-butyl-2-isopropyl anisole and 4,6-di-tert-butyl-2,3-dimethyl anisole;

[0093] (5) Concentrated sulfuric acid solution is added to the mixture of 2,6-di-tert-butyl-4-ethyl anisole / 4,6-di-tert-butyl-2-isopropyl anisole obtained in the above step (3) or step (4) for reaction. After the reaction, an alkali solution is added for neutralization, and then layering is carried out. The obtained material layer is subjected to vacuum rectification to successively obtain 99% p-ethyl anisole, a mixture of p-ethyl anisole / o-isopropyl anisole, and o-isopropyl anisole;

[0094] (6) Concentrated sulfuric acid solution is added to the still residue 4,6-di-tert-butyl-3-ethyl anisole obtained in the above step (3) for reaction. After the reaction, an alkali solution is added for neutralization, and the obtained material layer is layered. The material layer is subjected to vacuum rectification to obtain m-ethyl anisole.

[0095] The method for producing m-ethylanisole and p-ethylanisole from xylenol phenol oil in the embodiments of the present invention involves extracting the xylenol phenol oil fraction with an aqueous alkali solution to obtain the upper layer of phenol-removed phenol oil and the aqueous layer of sodium phenate solution. After heating, impurities such as neutral oil in the sodium phenate aqueous solution can be removed, and then an etherification reaction is carried out with an alkylating agent to obtain water-insoluble dimethylphenylalkyl ethers, ethylphenylalkyl ethers, etc. The mixture or pure substance of various specific dimethylphenylalkyl ethers and ethylphenylalkyl ethers can be obtained by fractional distillation of the stratified material layer, which is convenient for subsequent separation of various dimethylphenylalkyl ethers and ethylphenylalkyl ethers by tert-butylation; in the method of the embodiments of the present invention, a basic catalyst, an etherification reagent are reacted with the xylenol phenol oil fraction, and the boiling points of substances such as dimethylbenzyl ether obtained are significantly lower than those of the corresponding xylenols (the melting points also decrease). Thus, the xylenols (which have formed ether compounds) can be separated from the phenol oil in the xylenol phenol oil fraction by stratification or direct fractional distillation, and at the same time, the preliminary separation of various dimethylphenylalkyl ethers is achieved. The phenol-removed phenol oil is sent for hydrogenation, reducing the production cost; in the method of the embodiments of the present invention, the boiling points of substances such as dimethylphenylalkyl ethers obtained are lower than the boiling points of the corresponding xylenols (the melting points also decrease significantly), the energy consumption during fractional distillation is reduced, and there will be no problem that the materials are prone to clogging the pipeline during fractional distillation, the operation is convenient, and the production cost is also reduced; in the method of the embodiments of the present invention, the relatively inexpensive xylenol phenol oil fraction is used, and the production cost of m-ethylanisole and p-ethylanisole is low, the economic benefit is very remarkable, and it has good market competitiveness; in the method of the embodiments of the present invention, the reaction conditions are mild, only ether compounds are formed during the reaction process, and basically no side reactions of alkylation and dealkylation on the benzene ring occur. Then, through reaction with isobutene, fractional distillation, de-tert-butylation, and fractional distillation, pure products of m-ethylanisole and p-ethylanisole are obtained, and the conversion rates of various xylenols and ethylphenols in the reaction can be controlled above 98%; in the method of the embodiments of the present invention, the process has good operability and strong usability, the economic benefit is remarkable, and it is convenient for popularization and application in industrial production.

[0096] In some embodiments, preferably, in the step (1), the preparation method of the xylenol phenol oil fraction includes: adding phenol-containing coal tar into the bottom of a distillation column, first removing water under normal pressure, and then carrying out vacuum distillation to successively obtain a light oil fraction below 170 °C, a phenol oil fraction of 170 - 230 °C, a cresol fraction of 230 - 240 °C, a catechol fraction of 240 - 250 °C, a 5-indanol fraction of 250 - 270 °C, and a resorcinol / hydroquinone fraction of 270 - 300 °C; among them, the phenol oil fraction of 170 - 230 °C is further distilled to obtain a xylenol phenol oil fraction of 209 - 222 °C.

[0097] In some embodiments, preferably, the phenolic substances in the xylenol phenolic oil fraction include: 2,4-xylenol 0.1 to 20 wt%, 2,5-xylenol 0.1 to 15 wt%, meta-para-ethylphenol 60 to 90 wt%, 3,4-xylenol 0.1 to 10 wt%, 2,3-xylenol 0.1 to 20 wt%, 3,5-xylenol 0.1 to 20 wt%, o-isopropylphenol 0.1 to 10 wt%.

[0098] In some embodiments, preferably, in the step (1), the aqueous alkali solution includes at least one of an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution. More preferably, the aqueous alkali solution is an aqueous sodium hydroxide solution.

[0099] In some embodiments, preferably, in the step (1), the molar ratio of the phenolic substances in the xylenol phenolic oil fraction to the alkali is 1:1 to 3;

[0100] And / or, in the step (1), the temperature for heating and stirring is 30 to 80 °C, and the time for heating and stirring is 0.5 to 2 h;

[0101] And / or, in the step (1), the temperature for heating and refluxing is 105 to 110 °C, and the time for heating and refluxing is 0.5 to 2 h.

[0102] In some embodiments, preferably, in the step (1), the alkylating agent includes at least one of an iodoalkane, a chloroalkane, a dialkyl sulfate, or a dialkyl carbonate;

[0103] And / or, the molar ratio of the phenolic substances in the xylenol phenolic oil fraction to the alkylating agent is 1:0.5 to 5. More preferably, the alkylating agent is dimethyl carbonate, the molar ratio of the phenolic substances in the xylenol phenolic oil fraction to the alkylating agent is 1:1 to 3, and the dimethyl carbonate is added to the reactor in a dropwise manner, and the temperature during dropwise addition is not higher than 80 °C.

[0104] In the embodiments of the present invention, the dosage of the alkylating agent is preferably selected. If the dosage of the alkylating agent is too low, it cannot ensure the complete etherification of the phenolic material, and raw materials such as xylenol will still exist in the product. The unreacted xylenol and the like are dissolved in the ether. During rectification, since the boiling point of 3,4-dimethylanisole is 203 °C, while the boiling point of 2,4 / 2,5-xylenol is 211 °C, the incomplete reaction of 2,4 / 2,5-xylenol has some influence on the extraction of 3,4-dimethylanisole, and has little influence on other dimethylanisoles or ethylanisoles, and the overall influence is not significant. Therefore, the degree of etherification reaction can be adjusted according to the composition of the xylenol phenolic oil. If the dosage of the alkylating agent is too high, the reaction yield is guaranteed, but excessive alkylating agents such as dimethyl carbonate will be dissolved in the etherified product generated by the reaction. A small amount of dimethyl carbonate dissolved in water will gradually hydrolyze in water, resulting in waste of the alkylating agent and increasing the burden on the treatment of wastewater. Before rectification, dimethyl carbonate is recovered at normal pressure first, and then the etherified product is obtained by vacuum rectification, and most of the dimethyl carbonate can be recovered. Excessive use of the alkylating agent has little influence on the product quality under normal temperature conditions, but will affect the product quality at high temperatures. Further preferably, the alkylating agent is dimethyl carbonate with lower toxicity, which improves the safety of production operation, reduces poisoning behavior, and is beneficial to the health of operators.

[0105] In some embodiments, preferably, in the step (1), the temperature of the etherification reaction is 0 to 150 °C, the time of the etherification reaction is 4 to 20 h, and the pressure required for the etherification reaction is 0 to 1 MPa. Further preferably, the temperature of the etherification reaction is 40 to 100 °C, and the pressure required for the etherification reaction is 0 to 1 MPa.

[0106] In some embodiments, preferably, in the step (1), after the etherification reaction, static separation is carried out at 70 to 90 °C;

[0107] And / or, the washing treatment includes: adding a sulfuric acid solution to the material layer and washing for 0.5 to 2 h, then separating the layers, washing the obtained material layer with water, and separating and removing the washing water.

[0108] In some embodiments, preferably, in the step (2), the pressure of the rectification treatment is -0.05 to 0.1 MPa, and the reflux ratio is 15 to 25:1;

[0109] And / or, in the step (2), the rectification still residue 1 mainly contains 3,4-dimethylanisole, and 3,4-dimethylanisole is obtained after rectifying the rectification still residue 1.

[0110] In some embodiments, preferably, in the step (3), the mass of the sulfuric acid solution is 1 to 5% of the mass of the 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole / o-isopropylbenzene mixture;

[0111] And / or, in the step (3), the temperature for introducing isobutene for reaction is 60-120°C, and after the reaction, an alkali solution is added to neutralize to pH 7-8

[0112] And / or, in the step (3), the mass of the isobutene is 1-3 times the mass of the 2,3-dimethylanisole / m -ethylanisole / p -ethylanisole / 2-isopropylanisole mixture;

[0113] And / or, in the step (3), after introducing the isobutene for reaction, sampling and analysis are carried out. When the content of 6-tert-butyl-3-ethylanisole is ≤0.5%, it indicates the end of the reaction.

[0114] In some embodiments, preferably, in the step (5), the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture;

[0115] And / or, in the step (5), the temperature of the reaction is 180-200°C, the reaction time is 1-3 h, sampling and analysis are carried out. When the content of 2-tert-butyl-4-ethylanisole is ≤0.5%, it indicates the end of the reaction, and after the reaction, an alkali solution is added to neutralize to pH 7-8.

[0116] In some embodiments, preferably, in the step (6), the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of 4,6-di-tert-butyl-3-ethylanisole;

[0117] And / or, in the step (6), the temperature of the reaction is 180-200°C, the reaction time is 1-3 h, sampling and analysis are carried out. When the content of 6-tert-butyl-3-ethylanisole is ≤0.5%, it indicates the end of the reaction, and after the reaction, an alkali solution is added to neutralize to pH 7-8.

[0118] In some embodiments, preferably, in the step (2), the separation of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture includes the following steps:

[0119] S1. Add the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture and the concentrated sulfuric acid solution into a reactor, and while stirring, heat up to 60-120°C and introduce isobutene for reaction;

[0120] S2. After the reaction is completed, add an alkaline solution to neutralize the pH to 7-8. After separating the aqueous layer, rectify the material layer to obtain diisobutene, 6-tert-butyl-2,4-dimethylanisole, intermediate fraction 1, 4-tert-butyl-2,5-dimethylanisole, intermediate fraction 2, and residue 2; the intermediate fraction 1 is 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole, the intermediate fraction 2 is 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole, and the residue 2 is 4,6-di-tert-butyl-2,3-dimethylanisole;

[0121] S3. Rectify the intermediate fraction 1 to obtain 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole; rectify the intermediate fraction 2 to obtain 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole;

[0122] S4. Deisobutenylation of tert-butylated products: Add concentrated sulfuric acid solution to 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole, and 4,6-di-tert-butyl-2,3-dimethylanisole respectively for deisobutenylation reaction. After the reaction is completed, add an alkaline solution to neutralize to pH 7-8. After stratification, rectify the obtained material layer to obtain 2,4-dimethylanisole, 2,5-dimethylanisole, and 2,3-dimethylanisole.

[0123] In some embodiments, preferably, in S1, the mass of the concentrated sulfuric acid solution is 1-5% of the mass of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture;

[0124] and / or, in S1, the mass of the isobutene is 1-3 times the mass of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture;

[0125] and / or, in S1, after introducing the isobutene for reaction, sampling and analysis shows that the reaction is completed when 6-tert-butyl-2,3-xylenol ≤ 0.5%;

[0126] and / or, in S2, the reflux ratio of the rectification is 10-25:1;

[0127] and / or, in S4, the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole, and 4,6-di-tert-butyl-2,3-dimethylanisole respectively;

[0128] and / or, in S4, the temperature of the deisobutenylation reaction is 180-200 °C, and the time of the deisobutenylation reaction is 1-3 h.

[0129] In some embodiments, preferably, in step (2), the separation method of the o-isopropyl anisole / 3,4-dimethyl anisole mixture comprises the following steps:

[0130] (a) Add concentrated sulfuric acid solution to the o-isopropyl anisole / 3,4-dimethyl anisole mixture, stir and heat up to 60 - 120 °C, introduce isobutene for reaction. After the reaction is completed, add alkali solution to neutralize to pH 7 - 8, separate the layers, and subject the obtained material layer to vacuum distillation to obtain 6-tert-butyl-3,4-dimethyl anisole, and the residue in the kettle is 4,6-di-tert-butyl-2-isopropyl anisole. Recover isobutene for reuse;

[0131] (b) Deisobutenylation of tert-butylated products: Add concentrated sulfuric acid solution to 6-tert-butyl-3,4-dimethyl anisole and 4,6-di-tert-butyl-2-isopropyl anisole respectively for deisobutenylation reaction. After the reaction is completed, cool down and then add alkali solution to neutralize to pH 7 - 8. After separating the layers, subject the material layer to vacuum distillation to obtain 3,4-dimethyl anisole and 99% o-isopropyl anisole. Recover isobutene for reuse.

[0132] In some embodiments, preferably, in step (a), the mass of the concentrated sulfuric acid solution is 0.5 - 3% of the mass of the o-isopropyl anisole / 3,4-dimethyl anisole mixture;

[0133] and / or, in step (a), the mass of the isobutene is 1 - 3 times the mass of the o-isopropyl anisole / 3,4-dimethyl anisole mixture;

[0134] and / or, in step (a), after introducing the isobutene for reaction, sample and analyze. When the content of 6-tert-butyl-2-isopropyl anisole ≤ 0.5%, it indicates that the reaction is completed;

[0135] and / or, in step (b), the mass of the concentrated sulfuric acid solution is 0.5 - 3% of the mass of 6-tert-butyl-3,4-dimethyl anisole and 4,6-di-tert-butyl-2-isopropyl anisole respectively;

[0136] and / or, in step (b), the temperature of the deisobutenylation reaction is 180 - 200 °C, and the time of the deisobutenylation reaction is 1 - 3 h.

[0137] In some embodiments, preferably, step (3) further comprises: subjecting the 4,6-di-tert-butyl-2,3-dimethyl anisole / 4,6-di-tert-butyl-3-ethyl anisole mixture to distillation treatment to obtain 4,6-di-tert-butyl-2,3-dimethyl anisole;

[0138] Concentrated sulfuric acid solution was added to 4,6 - di - tert - butyl - 2,3 - dimethylanisole, and the mixture was stirred and heated to 180 - 200 °C for reaction for 1 - 3 hours. Then, an alkali solution was added to neutralize it to pH 7 - 8, and after layering, the obtained material layer was subjected to vacuum distillation to successively obtain 2,3 - dimethylanisole;

[0139] Preferably, the mass of the concentrated sulfuric acid solution is 0.5 - 3% of the mass of 4,6 - di - tert - butyl - 2,3 - dimethylanisole;

[0140] During the reaction process, samples were taken for analysis. When the content of 6 - tert - butyl - 2,3 - dimethylanisole ≤ 0.5%, it indicated that the reaction was completed.

[0141] In some embodiments, preferably, in step (5), the reaction temperature for adding the concentrated sulfuric acid solution is 180 - 200 °C, the reaction time is 1 - 3 hours, and the alkali solution is added to neutralize it to pH 7 - 8.

[0142] In some embodiments, preferably, in step (6), the reaction temperature for adding the concentrated sulfuric acid solution is 180 - 200 °C, the reaction time is 1 - 3 hours, and the alkali solution is added to neutralize it to pH 7 - 8.

[0143] The method for producing m - ethylanisole and p - ethylanisole from xylenol phenol oil provided by the embodiments of the present invention may further include the following steps:

[0144] (A) Mix the xylenol phenol oil fraction and an aqueous alkali solution, let it stand and layer to obtain a dephenolized phenol oil layer and a water layer. First, heat and reflux to distill out the neutral oil in the water layer, and then add an alkylating agent to the water layer for etherification reaction. After the reaction, let it stand to obtain a material layer and a water layer. The phenolic substances in the xylenol phenol oil fraction include: 30 - 100 wt% of m - p - ethylphenol, 0.1 - 30 wt% of 2,3 - xylenol, and 0.1 - 50 wt% of 3,5 - xylenol;

[0145] (B) Subject the material layer to rectification treatment to obtain a mixture of 2,3 - dimethylanisole / m - ethylanisole / 3,5 - dimethylanisole and the still residue;

[0146] (C) Concentrated sulfuric acid is added to the mixture of 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole obtained in step (B), and isobutene is introduced for reaction, then an alkaline solution is introduced for neutralization. After separating the aqueous layer, the material layer is subjected to vacuum distillation to successively obtain diisobutene, 3,5-dimethylanisole, 2,6-di-tert-butyl-4-ethylanisole, a mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole, 4,6-di-tert-butyl-2,3-dimethylanisole, a mixture of 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole, and the still residue 4,6-di-tert-butyl-3-ethylanisole; the mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole is subjected to rectification to obtain 2,6-di-tert-butyl-4-ethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole; the mixture of 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole is subjected to rectification to obtain 4,6-di-tert-butyl-2,3-dimethylanisole;

[0147] (D) Concentrated sulfuric acid is added to 2,6-di-tert-butyl-4-ethylanisole for reaction, then an alkaline solution is added for neutralization and layering treatment, and the obtained material layer is subjected to vacuum distillation to obtain p-ethylanisole;

[0148] (E) Concentrated sulfuric acid is added to 4,6-di-tert-butyl-3-ethylanisole for reaction, then an alkaline solution is added for neutralization and layering treatment, and the obtained material layer is subjected to vacuum distillation to obtain m-ethylanisole.

[0149] In some embodiments, preferably, in step (A), the preparation method of the xylenol phenol oil fraction includes: adding phenol-containing coal tar to the bottom of the rectification column, first removing water under atmospheric pressure, and then performing vacuum distillation to successively obtain a light oil fraction below 170 °C, a phenol oil fraction of 170 - 230 °C, a cresol fraction of 230 - 240 °C, a catechol fraction of 240 - 250 °C, a 5-indanol fraction of 250 - 270 °C, and a resorcinol / hydroquinone fraction of 270 - 300 °C; among them, the phenol oil fraction of 170 - 230 °C is further rectified to obtain a xylenol phenol oil fraction of 209 - 222 °C;

[0150] And / or, in step (A), the phenolic substances in the xylenol phenol oil fraction are composed of: m,p-ethylphenol 30 - 100 wt%, 2,3-xylenol 0.1 - 30 wt%, 3,5-xylenol 0.1 - 50 wt%;

[0151] And / or, in step (A), the alkaline aqueous solution includes at least one of an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution;

[0152] And / or, in the step (A), the molar ratio of the phenolic substances in the xylenol phenolic oil fraction to the base is 1:1 to 3;

[0153] And / or, in the step (A), the xylenol phenolic oil fraction and the aqueous base solution are mixed, first heated and stirred and then allowed to stand for separation. The temperature for heating and stirring is 30 to 80 °C, and the time for heating and stirring is 0.5 to 2 h;

[0154] And / or, in the step (A), the temperature for heating under reflux is 105 to 110 °C, and the time for heating under reflux is 0.5 to 2 h;

[0155] And / or, in the step (A), the alkylating agent includes at least one of iodoalkanes, chloroalkanes, dialkyl sulfates or dialkyl carbonates;

[0156] And / or, in the step (A), the molar ratio of the phenolic substances in the xylenol phenolic oil fraction to the alkylating agent is 1:0.5 to 5;

[0157] And / or, in the step (A), the temperature of the etherification reaction is 0 to 150 °C, the time of the etherification reaction is 4 to 20 h, and the pressure required for the etherification reaction is 0 to 1 MPa;

[0158] And / or, in the step (A), after the etherification reaction, it is allowed to stand for separation at 70 to 90 °C;

[0159] And / or, in the step (A), the washing includes: adding a sulfuric acid solution to the material layer for washing for 0.5 to 2 h, then separating the layers, washing the obtained material layer with water, and separating and removing the washing water;

[0160] And / or, in the step (B), the pressure of the rectification treatment is -0.05 to 0.1 MPa, the reflux ratio of the rectification treatment is 20 to 25:1, the bottom residue is a mixture of 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole and other inevitable impurities, and the bottom residue is used for rectification to obtain a mixture of 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole;

[0161] And / or, in the step (C), the amount of concentrated sulfuric acid used is 1 to 5% of the mass of the mixture of 2,3-dimethylanisole / m -p-ethylanisole / 3,5-dimethylanisole, and the mass of isobutene is 1 to 3 times the mass of the mixed m -p-methylanisole;

[0162] And / or, in the step (C), the reaction temperature for introducing isobutene is 60 - 120°C. During the reaction process, samples are taken for analysis. When the content of 6-tert-butyl-3-ethyl anisole ≤ 0.5%, it indicates the end of the reaction; an alkali solution is introduced to neutralize the pH to 7 - 8, and the reflux ratio of the vacuum distillation is 15 - 30:1;

[0163] And / or, it further includes the step (F), adding concentrated sulfuric acid to 4,6-di-tert-butyl-2,3-dimethyl anisole, reacting, then adding an alkali solution for neutralization and separation by layers, and subjecting the obtained material layer to vacuum distillation to obtain 2,3-dimethyl anisole

[0164] In some embodiments, preferably, in the step (D), the mass of the concentrated sulfuric acid is 1 - 5% of the mass of 2,6-di-tert-butyl-4-ethyl anisole, the reaction temperature is 150 - 200°C, and the reaction time is 1 - 3 h; an alkali solution is added to neutralize the pH to 7 - 8, and the reflux ratio of the vacuum distillation is 20 - 25:1.

[0165] In some embodiments, preferably, in the step (E), the mass of the concentrated sulfuric acid is 1 - 5% of the mass of 4,6-di-tert-butyl-3-ethyl anisole, the reaction temperature is 150 - 200°C, and the reaction time is 1 - 3 h; an alkali solution is added to neutralize the pH to 7 - 8, and the reflux ratio of the vacuum distillation is 20 - 25:1.

[0166] In some embodiments, preferably, in the step (F), the mass of the concentrated sulfuric acid is 1 - 5% of the mass of 4,6-di-tert-butyl-2,3-dimethyl anisole, the reaction temperature is 150 - 200°C, and the reaction time is 1 - 3 h; an alkali solution is added to neutralize the pH to 7 - 8, and the reflux ratio of the vacuum distillation is 20 - 25:1.

[0167] The embodiments of the present invention also provide a synthesis of xylenol:

[0168] Mix any one of the above-prepared p-ethylanisole, 2,5-dimethylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, o-isopropylanisole or any one of the above-prepared p-ethylanisole, 3,5-dimethylanisole, 2,3-dimethylanisole with mesitylene, heat up to 130-150 °C, dropwise add 45-55% hydrobromic acid and react for 4-6 h. The generated methyl bromide gas is cooled to -10 °C by a condenser and a two-stage cold trap and enters the alkyl bromide storage tank. After the reaction is completed, stop collecting the alkyl bromide, collect the generated methyl bromide, then slightly cool the reaction solution and separate out the aqueous hydrobromic acid solution. Wash the solvent layer once and then separate the layers. Combine the water layers to obtain the recovered hydrobromic acid solution. Send the hydrobromic acid solution to other sections for concentrating and recovering 47% hydrobromic acid. Subject the material layer to vacuum distillation to obtain xylenol, and recycle the mesitylene for reuse;

[0169] Preferably, the mesitylene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene;

[0170] And / or, the dosage of the mesitylene is 1-3 times the mass of the m-ethylanisole or p-ethylanisole;

[0171] And / or, the molar ratio of hydrogen bromide to m-ethylanisole or p-ethylanisole in the hydrobromic acid is 1-3. Further preferably, add the mesitylene and heat up to 110-140 °C; and / or, the concentration of the hydrobromic acid is 30-60%.

[0172] In the embodiment of the present invention, high-purity p-ethylphenol is generated by reacting hydrobromic acid with p-ethylanisole.

[0173] In the embodiment of the present invention, high-purity 2,5-xylenol is generated by reacting hydrobromic acid with 2,5-dimethylanisole, which can be used for vitamin E, gemfibrozil, etc., and has great economic benefits.

[0174] In the embodiment of the present invention, high-purity 3,4-xylenol is generated by reacting hydrobromic acid with 3,4-dimethylanisole. 3,4-xylenol is a raw material for the special engineering plastic soluble polyimide.

[0175] In the embodiment of the present invention, high-purity 3,5-xylenol is generated by reacting hydrobromic acid with 3,5-dimethylanisole, and high-efficiency fungicide 4-chloro-3,5-xylenol, etc. are produced.

[0176] In the embodiment of the present invention, high-purity o-isopropylphenol is generated by reacting hydrobromic acid with o-isopropylanisole. o-Isopropylphenol is used to synthesize the pesticide isoprocarb and antibacterial drugs, etc.

[0177] In the embodiment of the present invention, high-purity 2,3-xylenol is generated by reacting hydrobromic acid with 2,3-dimethylanisole.

[0178] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0179] Example 1

[0180] (1) Cutting of xylenol phenol oil fraction (boiling range 209 - 222 °C):

[0181] 640,000 parts of phenol - containing coal tar from coal pyrolysis of an energy enterprise in Xinjiang were added to the bottom of the distillation column. First, 1,104.8 parts of water were removed (at 200 mmHg column), and then under reduced pressure (200 - 5 mmHg column), distillation was carried out to obtain 8,645 parts of light oil fraction below 170 °C, 88,239 parts of phenol oil fraction at 170 - 230 °C, 13,156 parts of cresol phenol oil fraction at 230 - 240 °C, 11,711 parts of catechol phenol oil fraction at 240 - 250 °C, 36,929 parts of 5 - indanol phenol oil fraction at 250 - 270 °C, and 59,524 parts of resorcinol / hydroquinone phenol oil fraction at 270 - 300 °C in sequence.

[0182] 40,000 parts of the phenol oil fraction at 170 - 230 °C were added to the distillation kettle, and after distillation, 10,084 parts of mixed xylenol phenol oil were obtained. The content of phenolic products in the phenol oil was 47.6%, and the phenolic composition was 2,4 / 2,5 - xylenol 24 wt% (2,4 - xylenol 13.6 wt%, 2,5 - xylenol 10.4 wt%), 3,5 - xylenol 23 wt%, m - p - ethylphenol 32 wt% (m - ethylphenol 17.4 wt%, p - ethylphenol 14.6 wt%), 2,3 - xylenol 8.1 wt%, 3,4 - xylenol 8 wt%, and o - isopropylphenol 4.9 wt%.

[0183] (2) Extraction of xylenol phenol oil fraction

[0184] 10,084 parts of the mixed xylenol phenol oil (containing 4,800 parts of phenol) obtained in step (1) and 10,178 parts of 20% sodium hydroxide aqueous solution (the molar ratio of phenolic substances in cresol phenol oil to sodium hydroxide is 1:1.30) were added to the enamel reaction kettle. Stirring was started, and the temperature was raised to 80 °C and stirred for 1 hour, then left to stand for 1 hour for stratification, obtaining 14,966.5 parts of aqueous solution and separating out 5,251 parts of dephenolized phenol oil.

[0185] 15,006.5 parts of the aqueous solution (containing sodium xylenolate) were added to the reaction kettle equipped with a reflux water separator, and the temperature was raised to 105 - 110 °C to remove neutral oil. The time for removing neutral oil was 1 hour. At this time, the distilled water was clear and transparent, and the distillation was ended. The temperature was lowered to 65 °C, and another 40.2 parts of neutral oil were removed. The neutral oil was incorporated into the dephenolized phenol oil (total neutral oil 5,291.3 parts).

[0186] (3) Etherification of phenolate and washing of etherified product

[0187] The aqueous solution of sodium xylenolate in the reactor after removing neutral oil is cooled to 65°C, the stirring is started, and 2290 parts of dimethyl carbonate (the molar ratio of dimethyl carbonate to phenolic substances is 0.65:1) are added dropwise. The dropping time is 5 hours. After dropping, the mixture is kept at 95 - 100°C for 4 hours for sampling and analysis. The content of m-ethylphenol is 0.18%, which is qualified. Then it is cooled to 80°C and allowed to stand for layering. The lower aqueous layer is separated and sent to the wastewater treatment station. 300 parts of water are added to the material layer, and 50 parts of sulfuric acid are added dropwise under stirring for 1 hour to remove aniline and pyridine base. The pH of the aqueous solution is 4, and then it is layered. The material layer is washed with 200 parts of water, and the water is completely separated. The washed material layer is subjected to the following treatment.

[0188] (4) Rectification separation of etherified products

[0189] The above-mentioned material layer is added to a rectification kettle, and rectification is carried out under reduced pressure (-0.085 MPa). The reflux ratio is 20 - 25:1. For every 4 hours of rectification, total reflux is carried out for 1.5 hours. Under chromatographic analysis, 1461.7 parts of a mixture of 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole (719.1 parts of 2,4-dimethylanisole, 549.9 parts of 2,5-dimethylanisole, 192.7 parts of 2,3-dimethylanisole), 3258.8 parts of a mixture of 2,3-dimethylanisole / p-ethylanisole / m-ethylanisole / 3,5-dimethylanisole / o-isopropylbenzene (235.6 parts of 2,3-dimethylanisole, 772 parts of p-ethylanisole, 919.8 parts of m-ethylanisole, 1216.1 parts of 3,5-dimethylanisole, 115.3 parts of o-isopropylbenzene), and 310.1 parts of a mixture of o-isopropylbenzene / 3,4-dimethylanisole (140.9 parts of o-isopropylbenzene, 169.2 parts of 3,4-dimethylanisole) are accurately collected. The residue in the kettle is 255.1 parts (253.8 parts of 3,4-dimethylanisole).

[0190] The residue in the kettle is added to another rectification column (50 parts of a high-boiling solvent are added to the kettle as the bottom liquid), and rectification is carried out under reduced pressure (-0.085 MPa). The reflux ratio is 5 - 10:1, and 248.1 parts of 99.85% 3,4-dimethylanisole are obtained.

[0191] (5) Separation of 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture by tert-butylation

[0192] S1: Add 1461.7 parts of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture from step (4) (719.1 parts of 2,4-dimethylanisole, 549.9 parts of 2,5-dimethylanisole, and 192.7 parts of 2,3-dimethylanisole) and 50 parts of sulfuric acid (3.42% of the mass of the mixed dimethylanisole) into the reactor. While stirring, heat up to 60 °C and introduce 1800 parts of isobutene for reaction (1.23 times the mass of the mixed dimethylanisole). The time for introducing isobutene is 8 hours. After introducing isobutene, keep the temperature for reaction for 3 hours. Sampling analysis shows that 0.27% of 6-tert-butyl-2,3-dimethylanisole is qualified, and 992.8 parts of isobutene are recovered for reuse. Add 130 parts of 31% liquid caustic soda to neutralize to pH 8, separate the aqueous layer. Add the material layer into a high-efficiency rectification column and rectify at a reflux ratio of 10 - 25:1 to obtain 91.3 parts of diisobutene, 960.7 parts of 99.8% 6-tert-butyl-2,4-dimethylanisole, 68.7 parts of fraction 1 (40.8 parts of 6-tert-butyl-2,4-dimethylanisole, 27.9 parts of 4-tert-butyl-2,5-dimethylanisole), 679.1 parts of 99.3% 4-tert-butyl-2,5-dimethylanisole, 101.8 parts of fraction 2 (62.2 parts of 4-tert-butyl-2,5-dimethylanisole, 39.6 parts of 4,6-di-tert-butyl-2,3-dimethylanisole), and 306.4 parts of still residue 2 (305.3 parts of 4,6-di-tert-butyl-2,3-dimethylanisole).

[0193] Rectify fraction 1 to obtain 99% 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole; rectify fraction 2 to obtain 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole.

[0194] S2: Remove isobutene from the tert-butylated product and rectify

[0195] 960.7 parts of 99.8% 6-tert-butyl-2,4-dimethylanisole and 10 parts of 98% concentrated sulfuric acid (1.04% of the mass of 6-tert-butyl-2,4-dimethylanisole). Start stirring and heat up to 190 °C for reaction for 2 hours. Sampling analysis shows that the content of 6-tert-butyl-2,4-dimethylanisole is 0.41% qualified. Add 26 parts of 31% caustic soda solution to neutralize to pH 7.5, separate the layers. The material layer is rectified under reduced pressure to obtain 640.1 parts of 99.83% 2,4-dimethylanisole, with a yield of 94.1%, and 274.6 parts of isobutene are recovered for reuse.

[0196] 679.1 parts of 99.3% 4-tert-butyl-2,5-dimethylanisole and 10 parts of 98% concentrated sulfuric acid (1.47% of the mass of 4-tert-butyl-2,5-dimethylanisole). Start stirring and heat up to 200 °C for reaction for 1.5 hours. Take samples for analysis. When the content of 4-tert-butyl-2,5-dimethylanisole is 0.29%, it is qualified. Add 26 parts of 31% alkali solution to neutralize to pH 7.5. Separate the layers. The material layer is subjected to vacuum distillation to obtain 452.3 parts of 99.58% 2,5-dimethylanisole, and 194.1 parts of recycled isobutene are recycled for use.

[0197] 306.4 parts of still residue 2 (305.3 parts of 4,6-di-tert-butyl-2,3-dimethylanisole) and 5 parts of 98% concentrated sulfuric acid (1.63% of the mass of 4,6-di-tert-butyl-2,3-dimethylanisole). Start stirring and heat up to 200 °C for reaction for 2 hours. Take samples for analysis. When the content of 6-tert-butyl-2,3-dimethylanisole is 0.39%, it is qualified. Add 13 parts of 31% alkali solution to neutralize to pH 7.5. Separate the layers. The material layer is subjected to vacuum distillation to obtain 159.8 parts of 99.81% 2,3-dimethylanisole, with a yield of 95.3%. 134.2 parts of recycled isobutene are recycled for use.

[0198] (6) Separation of 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole mixture / o-isopropylbenzene

[0199] S1: Add 3258.8 parts of the 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole mixture / o-isopropylanisole in step (4) (235.6 parts of 2,3-dimethylanisole, 772 parts of p-ethylanisole, 919.8 parts of m-ethylanisole, 1216.1 parts of 3,5-dimethylanisole, 115.3 parts of o-isopropylanisole) and 90 parts of 98% sulfuric acid (2.76% of the mass of the mixed anisole) into the reactor. While stirring, heat up to 110 °C and introduce 3500 parts of isobutene for reaction (1.07 times the mass of the mixed anisole). The time for introducing isobutene is 5 hours. After introducing isobutene, keep the temperature for reaction for 2 hours. Take a sample for analysis. 0.12% of 6-tert-butyl-3-ethylanisole is qualified. Recover 1510.9 parts of the excessive isobutene. Add 232.5 parts of 31% liquid alkali to neutralize to pH 7 - 7.5. Separate the aqueous layer. Add the material layer into a high-efficiency rectifying column. Under a reflux ratio of 15 - 30:1, subject the material layer to vacuum rectification to obtain 190.6 parts of diisobutene, 1208.1 parts of 99.83% 3,5-dimethylanisole, a mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole 1467.5 parts (1283.4 parts of 2,6-di-tert-butyl-4-ethylanisole, 184.1 parts of 4,6-di-tert-butyl-2-isopropylanisole), a mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole 195.2 parts (104.6 parts of 2,6-di-tert-butyl-4-ethylanisole, 14.2 parts of 4,6-di-tert-butyl-2-isopropylanisole, 76.4 parts of 4,6-di-tert-butyl-2,3-dimethylanisole), 256.4 parts of 99.4% 4,6-di-tert-butyl-2,3-dimethylanisole, a mixture of 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole 226.8 parts (90.5 parts of 4,6-di-tert-butyl-2,3-dimethylanisole, 136.3 parts of 4,6-di-tert-butyl-3-ethylanisole), and 1525.3 parts of still residue (1521.2 parts of 4,6-di-tert-butyl-3-ethylanisole). Recover the isobutene parts for reuse.

[0200] The mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole is subjected to rectification treatment to obtain a mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole and 99% 4,6-di-tert-butyl-2,3-dimethylanisole; the mixture of 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole is subjected to rectification treatment to obtain 99% 4,6-di-tert-butyl-2,3-dimethylanisole.

[0201] S2: Deisobutenylation and rectification of tert-butylated product

[0202] 1467.5 parts of a mixture of 2,6-di-tert-butyl-4-ethyl anisole / 4,6-di-tert-butyl-2-isopropyl anisole (1283.4 parts of 2,6-di-tert-butyl-4-ethyl anisole and 184.1 parts of 4,6-di-tert-butyl-2-isopropyl anisole), 21 parts of 98% concentrated sulfuric acid (1.43% of the mass of the mixed anisole), start stirring, heat up to 200 °C for reaction for 2 hours, take samples for analysis, the content of 2-tert-butyl-4-ethyl anisole is 0.22% which is qualified, add 54.3 parts of 31% lye to neutralize to pH 7.5, separate the layers, and subject the material layer to vacuum rectification (reflux ratio 25 - 30:1, pre-add 100 parts of dimethyl diphenyl ether solvent with a boiling point of 285 °C to the bottom of the rectification column), obtaining 643.5 parts of 99.6% p-ethyl anisole, 86.3 parts of a mixture of p-ethyl anisole / o-isopropyl anisole (55.2 parts of p-ethyl anisole and 31.1 parts of o-isopropyl anisole), 71.2 parts of 99.1% o-isopropyl anisole; 645.1 parts of recycled isobutene are recycled for use.

[0203] 256.4 parts of 99.4% 4,6-di-tert-butyl-2,3-dimethyl anisole, 5 parts of 98% concentrated sulfuric acid (1.95% of the mass of 4,6-di-tert-butyl-2,3-dimethyl anisole), start stirring, heat up to 195 °C for reaction for 2 hours, take samples for analysis, the content of 6-tert-butyl-2,3-dimethyl anisole is 0.38% which is qualified, add 13 parts of 31% lye to neutralize to pH 7.5, separate the layers, and subject the material layer to vacuum rectification to obtain 133.5 parts of 99.52% 2,3-dimethyl anisole, and 113.5 parts of recycled isobutene are recycled for use.

[0204] 1525.3 parts of still residue (1521.2 parts of 4,6-di-tert-butyl-3-ethyl anisole), 20 parts of 98% concentrated sulfuric acid (1.31% of the mass of the still residue), start stirring, heat up to 190 °C for reaction for 2.5 hours, take samples for analysis, the content of 6-tert-butyl-3-ethyl anisole is 0.26% which is qualified, add 52 parts of 31% lye to neutralize to pH 8, separate the layers, and subject the material layer to vacuum rectification to obtain 793.6 parts of 99.75% m-ethyl anisole in sequence, with a yield of 94.9%, and 675.1 parts of recycled isobutene are recycled for use.

[0205] (7) Separation of o-isopropyl anisole / 3,4-dimethyl anisole mixture

[0206] S1: 310.1 parts of o-isopropyl anisole / 3,4-dimethyl anisole (140.9 parts of o-isopropyl anisole, 169.2 parts of 3,4-dimethyl anisole), 9 parts of concentrated sulfuric acid (2.9% of the mass of the mixed dimethyl anisole), heated to 80 °C with stirring and reacted with 350 parts of isobutene (1.13 times the mass of the mixed dimethyl anisole). The time for introducing isobutene is 7 hours. After introduction, keep the temperature for reaction for 3 hours. Sampling analysis shows that 0.33% of 6-tert-butyl-2-isopropyl anisole is qualified. 141.9 parts of recycled isobutene are reused. Add 23.5 parts of 31% liquid caustic soda to neutralize to pH 8, separate the aqueous layer. The material layer is added to a high-efficiency rectification column and rectified at a reflux ratio of 10 - 25:1 to obtain 19.1 parts of diisobutene and 231.8 parts of 99.6% 6-tert-butyl-3,4-dimethyl anisole, and 229.1 parts of still residue (227.1 parts of 4,6-di-tert-butyl-2-isopropyl anisole).

[0207] S2: Removal of isobutene and rectification of tert-butylated product

[0208] 231.8 parts of 99.6% 6-tert-butyl-3,4-dimethyl anisole, 3 parts of 98% concentrated sulfuric acid (1.29% of the mass of 4,6-di-tert-butyl-3,4-dimethyl anisole). Start stirring, heat to 200 °C for reaction for 1.5 hours. Sampling analysis shows that the content of 6-tert-butyl-3,4-dimethyl anisole is 0.44% qualified. Add 8 parts of 31% caustic soda solution to neutralize to pH 8, separate the layers. The material layer is rectified under reduced pressure to obtain 156 parts of 99.89% 3,4-dimethyl anisole, and 66.2 parts of recycled isobutene are reused.

[0209] 229.1 parts of still residue (227.1 parts of 4,6-di-tert-butyl-2-isopropyl anisole), 3 parts of 98% concentrated sulfuric acid (1.31% of the mass of the still residue). Start stirring, heat to 200 °C for reaction for 2 hours. Sampling analysis shows that the content of 6-tert-butyl-2-isopropyl anisole is 0.15% qualified. Add 8 parts of 31% caustic soda solution to neutralize to pH 8, separate the layers. The material layer is rectified under reduced pressure to obtain 123.6 parts of 99.52% o-isopropyl anisole, and 95.9 parts of recycled isobutene are reused.

[0210] (8) Synthesis of 2,5-xylenol, etc.

[0211] Add 248.1 parts of 99.85% 3,4 - dimethylanisole obtained in step (4) and 300 parts of mixed trimethylbenzenes into the reactor, heat up to 130 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to -10 °C by a condenser and a two - stage cold trap and enters the alkyl bromide storage tank (-15 °C). After the reaction is completed, stop collecting the alkyl bromide. A total of 600 parts of 47% hydrobromic acid is dropwise added, 168.8 parts of methyl bromide is collected, and the yield is 97.5%. Then, after the reaction solution is slightly cooled, the hydrobromic acid aqueous solution is separated out. The solvent layer is washed once with 20 parts of water, layered, and the water layers are combined to obtain 470.3 parts of 28.4% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 294.8 parts of trimethylbenzene is recovered from the material layer in the distillation kettle for reuse, and then 213.7 parts of 99.93% 3,4 - dimethylphenol is obtained by distillation.

[0212] Add 300 parts of 99.58% 2,5 - dimethylanisole obtained in step (5) S2 and 300 parts of mixed trimethylbenzenes into the reactor, heat up to 130 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to -10 °C by a condenser and a two - stage cold trap and enters the alkyl bromide storage tank (-15 °C). After the reaction is completed, stop collecting the alkyl bromide. A total of 700 parts of 47% hydrobromic acid is dropwise added, 203 parts of methyl bromide is collected, and the yield is 96.9%. Then, after the reaction solution is slightly cooled, the hydrobromic acid aqueous solution is separated out. The solvent layer is washed once with 20 parts of water, layered, and the water layers are combined to obtain 539.8 parts of 27.8% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 295.1 parts of trimethylbenzene is recovered from the material layer in the distillation kettle for reuse, and then 259.3 parts of 99.85% 2,5 - dimethylphenol is obtained by distillation.

[0213] Add 600 parts of 99.83% 3,5 - dimethylanisole obtained in step (6) S1 and 600 parts of mixed trimethylbenzenes into the reactor, heat up to 135 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to -10 °C by a condenser and a two - stage cold trap and enters the alkyl bromide storage tank (-15 °C). After the reaction is completed, stop collecting the alkyl bromide. A total of 1300 parts of 47% hydrobromic acid is dropwise added, 203 parts of methyl bromide is collected, and the yield is 96.9%. Then, after the reaction solution is slightly cooled, the hydrobromic acid aqueous solution is separated out. The solvent layer is washed once with 50 parts of water, layered, and the water layers are combined to obtain 987.3 parts of 27.5% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 587.4 parts of trimethylbenzene is recovered from the material layer in the distillation kettle for reuse, and then 519.5 parts of 99.9% 3,5 - dimethylphenol is obtained by distillation.

[0214] Add 300 parts of 99.6% p - ethyl anisole obtained in step (6) S2 and 300 parts of mixed trimethylbenzenes into the reactor, heat up to 135 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to - 10 °C by a condenser and a double cold trap and enters the alkyl bromide storage tank (- 15 °C). After the reaction is completed, stop collecting alkyl bromide. A total of 800 parts of 47% hydrobromic acid is dropwise added, and 202.2 parts of methyl bromide is collected, with a yield of 96.5%. Then, after the reaction solution is slightly cooled, the hydrobromic acid aqueous solution is separated out. The solvent layer is washed once with 30 parts of water, layered, and the water layers are combined to obtain 643.5 parts of 30.1% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 293.4 parts of trimethylbenzene is recovered from the material layer in the distillation kettle for reuse, and then 259 parts of 99.7% p - ethyl phenol is obtained by distillation.

[0215] Add 123.6 parts of 99.52% o - isopropyl anisole obtained in step (7) S2 and 150 parts of mixed trimethylbenzenes into the reactor, heat up to 135 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to - 10 °C by a condenser and a double cold trap and enters the alkyl bromide storage tank (- 15 °C). After the reaction is completed, stop collecting alkyl bromide. A total of 280 parts of 47% hydrobromic acid is dropwise added, and 76.1 parts of methyl bromide is collected, with a yield of 97.3%. Then, after the reaction solution is slightly cooled, the hydrobromic acid aqueous solution is separated out. The solvent layer is washed once with 10 parts of water, layered, and the water layers are combined to obtain 220.6 parts of 28.6% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 146.5 parts of trimethylbenzene is recovered from the material layer in the distillation kettle for reuse, and then 107.3 parts of 99.6% o - isopropyl phenol is obtained by distillation.

[0216] Example 2

[0217] (1) Cutting of m - p - ethyl phenol / 3,5 - xylenol / 2,3 - xylenol phenol oil fraction (boiling range 217.5 - 219 °C):

[0218] Add 960000 parts of phenol - containing coal tar from coal pyrolysis of an energy enterprise in Xinjiang into the bottom of the distillation column. First, (200 mmHg column) remove 1657.2 parts of water, and then under reduced pressure (200 - 5 mmHg column), distill to obtain 12967.5 parts of light oil fraction < 170 °C, 132358.5 parts of phenol oil fraction 170 - 230 °C, 19734 parts of cresol phenol oil fraction 230 - 240 °C, 17566.5 parts of catechol phenol oil fraction 240 - 250 °C, 55393.5 parts of 5 - indanol phenol oil fraction 250 - 270 °C, and 89286 parts of resorcinol / hydroquinone phenol oil fraction 270 - 300 °C in sequence.

[0219] Add 72,000 parts of phenol oil fraction at 170 - 230 °C to a distillation kettle (about 250 theoretical plates), and distill at -0.085 MPa and a reflux ratio of 25 - 30:1 to collect the fraction at 217 - 219.5 °C, obtaining 3,684 parts of m,p-ethylphenol / 3,5-xylenol / 2,3-xylenol phenol oil fraction with a phenol content of 50.3% and 1,853 parts of phenol (91.2 parts of 3,5-xylenol, 883.2 parts of m-ethylphenol, 736.8 parts of p-ethylphenol, 127.2 parts of 2,3-xylenol, and 14.6 parts of others).

[0220] (2) Salt formation of xylenol fraction

[0221] Add 3,684 parts of m,p-ethylphenol / 3,5-xylenol / 2,3-xylenol phenol oil fraction (containing 1,853 parts of phenol) obtained in step (1) and 4,253 parts of 20% aqueous sodium hydroxide solution (the molar ratio of phenolic substances in the phenol-containing phenol oil to sodium hydroxide is 1:1.40) to an enamel reaction kettle. Start stirring, heat up to 75 °C and stir for 1 hour, then let it stand for 1 hour to separate layers, obtaining 6,108.8 parts of aqueous solution and separating 1,821.2 parts of phenol-depleted phenol oil.

[0222] Add 6,108.8 parts of aqueous solution (containing sodium salts of m,p-ethylphenol, etc.) to a reaction kettle equipped with a reflux water separator, heat up to 105 - 110 °C to remove neutral oil for 1.5 hours. At this time, the distilled water is clear and transparent, and the water returns to the kettle through the water separator to end the distillation. Cool down to 70 °C and remove another 6.5 parts of neutral oil. The neutral oil is incorporated into the phenol-depleted phenol oil (total neutral oil is 1,827.7 parts), obtaining 6,090.5 parts of aqueous solution of sodium salts of m,p-ethylphenol / 3,5-xylenol / 2,3-xylenol (containing 1,843.7 parts of phenol (90.7 parts of 3,5-xylenol, 878.8 parts of m-ethylphenol, 733.1 parts of p-ethylphenol, 126.6 parts of 2,3-xylenol, and 14.5 parts of others).

[0223] (3) Etherification of phenol sodium salt and washing of etherified product

[0224] Cool the 6,090.5 parts of aqueous solution of sodium salts of m,p-ethylphenol / 3,5-xylenol / 2,3-xylenol in the reactor to 70 °C, start stirring, and begin to dropwise add 1,362 parts of dimethyl carbonate (the molar ratio of dimethyl carbonate to phenolic substances is 1:1). The dropping time is 4.5 hours. After dropping, keep the temperature at 98 - 100 °C for 4 hours for sampling and analysis. The m-ethylphenol content of 0.31% is qualified, and 585 parts of dimethyl carbonate are recovered for reuse. Cool down to 75 °C and let it stand for layer separation. Separate the lower water layer, and send the water layer to the wastewater treatment station. Add 100 parts of water to the material layer and dropwise add 8 parts of sulfuric acid while stirring for 1 hour to remove aniline and pyridine bases. The pH of the aqueous solution is 4, then separate layers. Wash the material layer with 100 parts of water, drain all the water, and the washed material layer of 2,3-dimethylanisole / m,p-ethylanisole / 3,5-dimethylanisole mixture is subjected to the following treatment.

[0225] (4) Rectification separation of etherified products

[0226] Add the above material layer into the rectification still, and conduct rectification under reduced pressure (-0.085 MPa), with a reflux ratio of 20 - 25:1. For every 4 hours of rectification, conduct total reflux for 1.5 hours. Under chromatographic analysis, collect 1953.7 parts of the 2,3-dimethylanisole / m - and p - ethylanisole / 3,5-dimethylanisole mixture (135.5 parts of 2,3-dimethylanisole, 784.6 parts of p - ethylanisole, 940.5 parts of m - ethylanisole, 85.1 parts of 3,5-dimethylanisole, and 8 parts of others), and 80.4 parts of residue in the still (73.1 parts of the 2,3-dimethylanisole / m - and p - ethylanisole / 3,5-dimethylanisole mixture and 7.3 parts of others).

[0227] The residue in the still is used for rectifying the 2,3-dimethylanisole / m - and p - ethylanisole / 3,5-dimethylanisole mixture.

[0228] (5) Separation of the 2,3-dimethylanisole / m - and p - ethylanisole / 3,5-dimethylanisole mixture

[0229] S1: Add 1953.7 parts of the 2,3 - dimethylanisole / m - p - ethylanisole / 3,5 - dimethylanisole mixture in step (4) (135.5 parts of 2,3 - dimethylanisole, 784.6 parts of p - ethylanisole, 940.5 parts of m - ethylanisole, 85.1 parts of 3,5 - dimethylanisole, 8 parts of others) and 60 parts of 98% sulfuric acid (3.07% of the mass of the mixed anisoles) into the reactor. Heat up to 105°C with stirring and introduce 3000 parts of isobutene for reaction (1.535 times the mass of the mixed m - p - methylanisoles). The time for introducing isobutene is 7.5 hours. After introduction, keep the temperature for reaction for 2.5 hours. Sampling analysis shows that 0.24% of 6 - tert - butyl - 3 - ethylanisole is qualified. Recycle 1292.3 parts of the excessive isobutene for reuse. Add 155 parts of 31% liquid caustic soda to neutralize to pH 7.5, separate the aqueous layer. Add the material layer into a high - efficiency rectifying column (about 250 theoretical plates), and under a reflux ratio of 15 - 30:1, subject the material layer to vacuum rectification to obtain 179.6 parts of diisobutene, 82.6 parts of 99.72% 3,5 - dimethylanisole, 634.6 parts of 99.7% 2,6 - di - tert - butyl - 4 - ethylanisole, 157.3 parts of a 2,6 - di - tert - butyl - 4 - ethylanisole / 4,6 - di - tert - butyl - 2,3 - dimethylanisole mixture (135.6 parts of 2,6 - di - tert - butyl - 4 - ethylanisole, 21.7 parts of 4,6 - di - tert - butyl - 2,3 - dimethylanisole), 74.9 parts of 99.2% 4,6 - di - tert - butyl - 2,3 - dimethylanisole, 287.3 parts of a 4,6 - di - tert - butyl - 2,3 - dimethylanisole / 4,6 - di - tert - butyl - 3 - ethylanisole mixture (30.1 parts of 4,6 - di - tert - butyl - 2,3 - dimethylanisole, 257.2 parts of 4,6 - di - tert - butyl - 3 - ethylanisole), and 1453.4 parts of still residue (1440.7 parts of 4,6 - di - tert - butyl - 3 - ethylanisole).

[0230] The 2,6 - di - tert - butyl - 4 - ethylanisole / 4,6 - di - tert - butyl - 2,3 - dimethylanisole mixture is subject to double distillation to obtain 99% 2,6 - di - tert - butyl - 4 - ethylanisole and 99% 4,6 - di - tert - butyl - 2,3 - dimethylanisole; the 4,6 - di - tert - butyl - 2,3 - dimethylanisole / 4,6 - di - tert - butyl - 3 - ethylanisole mixture is subject to double distillation to obtain 99% 4,6 - di - tert - butyl - 2,3 - dimethylanisole.

[0231] S2: Deisobutenation and rectification of tert - butylated products

[0232] 634.6 parts of 99.7% 2,6 - di - tert - butyl - 4 - ethyl anisole and 7.2 parts of 98% concentrated sulfuric acid (1.13% of the mass of 2,6 - di - tert - butyl - 4 - ethyl anisole). Start stirring, heat up to 200 °C for reaction for 1.5 hours. Take a sample for analysis. The content of 2 - tert - butyl - 4 - ethyl anisole is 0.29% which is qualified. Add 18.6 parts of 31% lye to neutralize to pH 7.5. Separate the layers. The material layer is subjected to vacuum distillation (about 250 trays, reflux ratio 20 - 25, and 50 parts of dimethyl diphenyl ether solvent with a boiling point of 285 °C is pre - added to the bottom of the distillation column), and 343.1 parts of 99.9% p - ethyl anisole are obtained; 280.5 parts of isobutene are recovered and reused.

[0233] 74.9 parts of 99.2% 4,6 - di - tert - butyl - 2,3 - dimethyl anisole and 1.5 parts of 98% concentrated sulfuric acid (2.0% of the mass of 4,6 - di - tert - butyl - 2,3 - dimethyl anisole). Start stirring, heat up to 190 °C for reaction for 2.5 hours. Take a sample for analysis. The content of 6 - tert - butyl - 2,3 - dimethyl anisole is 0.17% which is qualified. Add 3.9 parts of 31% lye to neutralize to pH 7.5. Separate the layers. The material layer is subjected to vacuum distillation (reflux ratio 20 - 25), and 39 parts of 99.6% 2,3 - dimethyl anisole are obtained. 33.1 parts of isobutene are recovered and reused.

[0234] 1453.4 parts of still residue (1440.7 parts of 4,6 - di - tert - butyl - 3 - ethyl anisole) and 19 parts of 98% concentrated sulfuric acid (1.31% of the mass of the still residue). Start stirring, heat up to 195 °C for reaction for 2 hours. Take a sample for analysis. The content of 6 - tert - butyl - 3 - ethyl anisole is 0.24% which is qualified. Add 49.1 parts of 31% lye to neutralize to pH 7.5. Separate the layers. The material layer is subjected to vacuum distillation (reflux ratio 20 - 25) to obtain 746.2 parts of 99.61% m - ethyl anisole, with a yield of 94.1%. 637 parts of isobutene are recovered and reused.

[0235] (6) Synthesis of 3,5 - xylenol, etc.

[0236] Add 82.6 parts of 99.72% 3,5 - dimethyl anisole obtained in step (5) S1 and 90 parts of mixed trimethylbenzenes to the reaction kettle. Heat up to 135 - 140 °C and dropwise add 47% hydrobromic acid for reaction. The generated bromomethane gas is cooled to - 10 °C by a condenser and a two - stage cold trap and enters the bromoalkane storage tank (- 15 °C). After the reaction is completed, stop collecting bromoalkanes. A total of 179 parts of 47% hydrobromic acid are dropwise added, and 55.7 parts of bromomethane are collected, with a yield of 97.1%. Then, after the reaction solution is slightly cooled, the aqueous hydrobromic acid solution is separated out. The solvent layer is washed once with 6 parts of water, and the layers are separated. The water layers are combined to obtain 135 parts of 27.6% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 88.9 parts of trimethylbenzene are recovered from the distillation kettle of the material layer and reused. Then, 71.4 parts of 99.83% 3,5 - xylenol are obtained by distillation.

[0237] Add 343.1 parts of 99.9% p - ethylanisole obtained in step (5) S2 and 350 parts of mixed trimethylbenzenes into the reaction kettle, heat up to 135 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to - 10 °C by a condenser and a two - stage cold trap and enters the alkyl bromide storage tank (-15 °C). After the reaction is completed, stop collecting the alkyl bromide. A total of 915.8 parts of 47% hydrobromic acid is dropwise added, and 233.3 parts of methyl bromide is collected, with a yield of 97.3%. Then, after the reaction solution is slightly cooled, the aqueous hydrobromic acid solution is separated out. The solvent layer is washed once with 50 parts of water, layered, and the water layers are combined to obtain 742.1 parts of 29.7% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 345.8 parts of trimethylbenzene recovered from the distillation kettle of the material layer is recycled, and then 295.6 parts of 99.95% p - ethylphenol is obtained by distillation.

[0238] Add 39 parts of 99.6% 2,3 - dimethylanisole obtained in step (5) S1 and 50 parts of mixed trimethylbenzenes into the reaction kettle, heat up to 135 - 140 °C, dropwise add 47% hydrobromic acid for reaction. The generated methyl bromide gas is cooled to - 10 °C by a condenser and a two - stage cold trap and enters the alkyl bromide storage tank (-15 °C). After the reaction is completed, stop collecting the alkyl bromide. A total of 85 parts of 47% hydrobromic acid is dropwise added, and 26.1 parts of methyl bromide is collected, with a yield of 96.4%. Then, after the reaction solution is slightly cooled, the aqueous hydrobromic acid solution is separated out. The solvent layer is washed once with 3 parts of water, layered, and the water layers are combined to obtain 63.9 parts of 27.5% hydrobromic acid solution (sent for heating to recover 47% hydrobromic acid). 49.1 parts of trimethylbenzene recovered from the distillation kettle of the material layer is recycled, and then 33.6 parts of 99.75% 2,3 - dimethylphenol is obtained by distillation.

[0239] In the present invention, the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0240] Although the above - mentioned embodiments have been shown and described, it can be understood that the above - mentioned embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions, and variations made by those of ordinary skill in the art to the above - mentioned embodiments are within the protection scope of the present invention.

Claims

1. A method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil, characterized in that: The following steps are involved: (1) mixing a xylenol phenol oil fraction and an alkaline aqueous solution, standing to separate into layers to obtain a dephenolized phenol oil layer and a water layer, first heating and refluxing to evaporate the neutral oil in the water layer, then adding an alkylating agent to the water layer to carry out an etherification reaction, standing to obtain a material layer and a water layer after the reaction, and washing the material layer to obtain a material layer; The phenolic substances in the dimethylol phenol oil fraction include: 0.1-30wt% of 2,4-dimethylol, 0.1-20wt% of 2,5-dimethylol, 30-100wt% of m-p-ethylphenol, 0.1-50wt% of 3,4-dimethylol, 0.1-30wt% of 2,3-dimethylol, 0.1-50wt% of 3,5-dimethylol, and 0.1-20wt% of o-isopropylphenol; (2) subjecting the material layer to rectification treatment to obtain a 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture, a 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole mixture, an o-isopropylanisole / 3,4-dimethylanisole mixture and a rectification still residue 1; (3) adding concentrated sulfuric acid solution to the mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole obtained in step (2), introducing isobutylene, adding alkali solution to neutralize after the reaction, standing to obtain a material layer, and subjecting the material layer to vacuum distillation to obtain diisobutylene, 3,5-dimethylanisole, 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole in sequence; 4,6-di-tert-butyl-3-ethylanisole mixture, 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture, 4,6-di-tert-butyl-2,3-dimethylanisole, 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole mixture and still residue 4,6-di-tert-butyl-3-ethylanisole; (4) distilling the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture to obtain a 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture and 4,6-di-tert-butyl-2,3-dimethylanisole; (5) adding concentrated sulfuric acid solution to the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture obtained in step (3) or step (4) for reaction, adding alkali solution for neutralization after the reaction, layering, and subjecting the obtained material layer to vacuum distillation to sequentially obtain p-ethylanisole, a p-ethylanisole / o-isopropylanisole mixture, and o-isopropylanisole; (6) adding concentrated sulfuric acid solution to the still residue 4,6-di-tert-butyl-3-ethylanisole obtained in step (3) for reaction, adding alkali solution for neutralization after the reaction, separating the layers to obtain a material layer, and subjecting the material layer to vacuum distillation to obtain m-ethylanisole.

2. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 1, wherein: In the step (1), the preparation method of the xylenol phenol oil fraction comprises: adding phenol-containing coal tar into a distillation tower kettle, first removing water at normal pressure, and then distilling under reduced pressure to obtain a light oil fraction of less than 170°C, a phenol oil fraction of 170-230°C, a tricresol fraction of 230-240°C, a catechol fraction of 240-250°C, a 5-indanol fraction of 250-270°C, and a resorcinol / hydroquinone fraction of 270-300°C in sequence; wherein the phenol oil fraction of 170-230°C is further distilled to obtain a xylenol phenol oil fraction of 209-222°C; And / or, in step (1), the alkaline aqueous solution comprises at least one of a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution; and / or, in the step (1), the molar ratio of phenolic substances in the xylenol phenol oil fraction to the alkali is 1:1 to 3; And / or, in the step (1), the xylenol phenol oil fraction and the alkaline aqueous solution are mixed, heated and stirred, and then allowed to stand for stratification, the temperature of the heating and stirring is 30 to 80° C., and the time of the heating and stirring is 0.5 to 2 hours; And / or, in the step (1), the temperature of the heating and reflux is 105-110° C., and the time of the heating and reflux is 0.5-2 h; And / or, in the step (1), the alkylating agent comprises at least one of iodoalkanes, chloroalkanes, difatty sulfates or difatty carbonates; and / or, in the step (1), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkylating agent is 1:0.5-5; And / or, in the step (1), the temperature of the etherification reaction is 0 to 150° C., the time of the etherification reaction is 4 to 20 hours, and the pressure required for the etherification reaction is 0 to 1 MPa; And / or, in the step (1), after the etherification reaction is completed, the mixture is allowed to stand at 70 to 90° C. for stratification; And / or, in the step (1), the washing comprises: adding a sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, then washing the obtained material layer in layers with water, and removing the washing water in layers; And / or, in the step (2), the pressure of the distillation treatment is -0.05 to 0.1 MPa, and the reflux ratio is 15 to 25:1; And / or, in the step (2), the distillation still residue 1 mainly contains 3,4-dimethylanisole, and the distillation still residue 1 is distilled to obtain 3,4-dimethylanisole; And / or, in step (3), the mass of the concentrated sulfuric acid solution is 1 to 5% of the mass of the mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole; And / or, in the step (3), the temperature of introducing the isobutylene for reaction is 60 to 120° C., and after the reaction, alkaline solution is added to neutralize to pH 7 to 8; And / or, in the step (3), the mass of the isobutylene is 1 to 3 times the mass of the mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole / o-isopropylanisole; And / or, in the step (3), after the isobutylene is introduced for reaction, sampling and analysis are performed, and a 6-tert-butyl-3-ethylanisole content of ≤0.5% indicates that the reaction is complete; And / or, in step (5), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of the 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2-isopropylanisole mixture; And / or, in the step (5), the reaction temperature is 180-200° C., the reaction time is 1-3 h, sampling and analysis, 2-tert-butyl-4-ethylanisole content ≤ 0.5% indicates that the reaction is complete, and after the reaction, alkali solution is added to neutralize to pH 7-8; And / or, in step (6), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of 4,6-di-tert-butyl-3-ethylanisole; And / or, in the step (6), the reaction temperature is 180-200° C., the reaction time is 1-3 h, sampling and analysis, 6-tert-butyl-3-ethylanisole content ≤ 0.5% indicates the end of the reaction, and alkali solution is added after the reaction to neutralize to pH 7-8.

3. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 1, wherein: In the step (2), the separation of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture comprises the following steps: S1. Add a mixture of 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole and a concentrated sulfuric acid solution into a reactor, heat to 60-120° C. under stirring, and introduce isobutylene for reaction; S2, after the reaction is completed, alkali solution is added to neutralize the pH to 7-8, and after the water layer is separated, the material layer is distilled to obtain diisobutylene, 6-tert-butyl-2,4-dimethylanisole, transition fraction 1, 4-tert-butyl-2,5-dimethylanisole, transition fraction 2, and still residue 2; the transition fraction 1 is 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole, the transition fraction 2 is 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole, and the still residue 2 is 4,6-di-tert-butyl-2,3-dimethylanisole; S3, distilling the transition fraction 1 to obtain 6-tert-butyl-2,4-dimethylanisole and 4-tert-butyl-2,5-dimethylanisole; distilling the transition fraction 2 to obtain 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole; S4, deisobutylene treatment of tert-butylated products: Concentrated sulfuric acid solution is added to the 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole respectively to carry out deisobutylene reaction, and after the reaction, alkaline solution is added to neutralize to pH 7-8, and after separation, the obtained material layer is distilled to obtain 2,4-dimethylanisole, 2,5-dimethylanisole and 2,3-dimethylanisole.

4. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 3, wherein: In S1, the mass of the concentrated sulfuric acid solution is 1 to 5% of the mass of the 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole mixture; And / or, in S1, the mass of the isobutylene is 1 to 3 times the mass of the mixture of 2,4 / 2,5-dimethylanisole / 2,3-dimethylanisole; And / or, in S1, after the isobutylene is introduced for reaction, sampling and analysis of 6-tert-butyl-2,3-dimethylphenol ≤ 0.5% indicates that the reaction is complete; And / or, in S2, the reflux ratio of the distillation is 10 to 25:1; And / or, in S4, the mass of the concentrated sulfuric acid solution is 0.5-3% of the mass of 6-tert-butyl-2,4-dimethylanisole, 4-tert-butyl-2,5-dimethylanisole, and 4,6-di-tert-butyl-2,3-dimethylanisole, respectively; And / or, in S4, the temperature of the deisobutylene reaction is 180-200° C., and the time of the deisobutylene reaction is 1-3 h.

5. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 1, wherein: In the step (2), the method for separating the o-isopropylanisole / 3,4-dimethylanisole mixture comprises the following steps: (a) add concentrated sulfuric acid solution in o-isopropylanisole / 3,4-dimethylanisole mixture, stir and be warming up to 60~120 ℃ and pass into isobutylene reaction, after reaction finishes, add alkali lye and be neutralized to pH7~8, layer, the material layer rectification under reduced pressure obtained is obtained 6-tert-butyl-3,4-dimethylanisole, still residual 4,6-di-tert-butyl-2-isopropylanisole, reclaim isobutylene and apply mechanically; (b) Deisobutylene treatment of tert-butylated products: Concentrated sulfuric acid solution is added to 6-tert-butyl-3,4-dimethylanisole and 4,6-di-tert-butyl-2-isopropylanisole respectively to carry out deisobutylene reaction. After the reaction is completed, alkaline solution is added to neutralize to pH 7-8. After separation, the material layer is subjected to vacuum distillation to obtain 3,4-dimethylanisole and o-isopropylanisole, and isobutylene is recovered for reuse.

6. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 5, characterized in that, In the step (a), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of the o-isopropylanisole / 3,4-dimethylanisole mixture; And / or, in the step (a), the mass of the isobutylene is 1 to 3 times the mass of the mixture of o-isopropylanisole / 3,4-dimethylanisole; And / or, in the step (a), after the isobutylene is introduced into the reaction and a sample is taken for analysis, a 6-tert-butyl-2-isopropylanisole content of ≤0.5% indicates that the reaction is complete; And / or, in step (b), the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of 6-tert-butyl-3,4-dimethylanisole and 4,6-di-tert-butyl-2-isopropylanisole respectively; And / or, in the step (b), the temperature of the deisobutylene reaction is 180-200° C., and the time of the deisobutylene reaction is 1-3 hours.

7. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 1, wherein: The step (3) further comprises: distilling the 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole mixture to obtain 4,6-di-tert-butyl-2,3-dimethylanisole; Add concentrated sulfuric acid solution to 4,6-di-tert-butyl-2,3-dimethylanisole, stir and heat to 180-200° C. to react for 1-3 hours, then add alkali solution to neutralize to pH 7-8, separate layers, and perform vacuum distillation on the obtained material layers to obtain 2,3-dimethylanisole in turn; Preferably, the mass of the concentrated sulfuric acid solution is 0.5 to 3% of the mass of 4,6-di-tert-butyl-2,3-dimethylanisole; During the reaction, sampling and analysis were performed, and if the content of 6-tert-butyl-2,3-dimethylanisole was ≤0.5%, it indicated that the reaction was complete.

8. A method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil, characterized in that: The following steps are involved: (A) mixing a xylenol phenol oil fraction and an alkaline aqueous solution, standing to separate into layers to obtain a dephenolized phenol oil layer and a water layer, first heating and refluxing to evaporate the neutral oil in the water layer, then adding an alkylating agent to the water layer to carry out an etherification reaction, standing to obtain a material layer and a water layer after the reaction, and washing the material layer to obtain a material layer; The phenolic substances in the dimethylol phenol oil fraction include: 30-100wt% of m-p-ethylphenol, 0.1-30wt% of 2,3-dimethylphenol, and 0.1-50wt% of 3,5-dimethylphenol; (B) subjecting the material layer to rectification treatment to obtain a 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole mixture and a kettle residue; (C) adding concentrated sulfuric acid to the 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole mixture obtained in step (B), passing isobutylene to react, then passing alkali solution to neutralize, dividing the water layer and subjecting the material layer to vacuum distillation to obtain diisobutylene, 3,5-dimethylanisole, 2,6-di-tert-butyl-4-ethylanisole, 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole mixture, 4,6-di-tert-butyl-2,3-dimethylanisole, 4,6-di-tert-butyl-2,3 -dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole mixture and still residue 4,6-di-tert-butyl-3-ethylanisole; distilling a mixture of 2,6-di-tert-butyl-4-ethylanisole / 4,6-di-tert-butyl-2,3-dimethylanisole to obtain 2,6-di-tert-butyl-4-ethylanisole and 4,6-di-tert-butyl-2,3-dimethylanisole; distilling a mixture of 4,6-di-tert-butyl-2,3-dimethylanisole / 4,6-di-tert-butyl-3-ethylanisole to obtain 4,6-di-tert-butyl-2,3-dimethylanisole; (D) adding concentrated sulfuric acid to 2,6-di-tert-butyl-4-ethyl anisole and then adding alkali lye to neutralize and layer the material layer, and carrying out rectification under reduced pressure to obtain p-ethyl anisole; (E) adding concentrated sulfuric acid to 4,6-di-tert-butyl-3-ethylanisole, adding alkali solution for reaction and neutralizing, and layering, and subjecting the obtained material layer to rectification under reduced pressure to obtain m-ethylanisole.

9. The method for producing m-ethyl anisole and p-ethyl anisole from xylenol phenol oil according to claim 8, wherein: In the step (A), the preparation method of the xylenol phenol oil fraction comprises: adding phenol-containing coal tar into a distillation tower kettle, first removing water at normal pressure, and then distilling under reduced pressure to obtain a light oil fraction of less than 170°C, a phenol oil fraction of 170-230°C, a tricresol fraction of 230-240°C, a catechol fraction of 240-250°C, a 5-indanol fraction of 250-270°C, and a resorcinol / hydroquinone fraction of 270-300°C in sequence; wherein the phenol oil fraction of 170-230°C is further distilled to obtain a xylenol phenol oil fraction of 209-222°C; And / or, in step (A), the alkaline aqueous solution comprises at least one of a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution; and / or, in the step (A), the molar ratio of phenolic substances in the xylenol phenol oil fraction to the alkali is 1:1 to 3; And / or, in the step (A), the xylenol phenol oil fraction is mixed with an alkaline aqueous solution, first heated and stirred, and then allowed to stand for stratification, the temperature of the heating and stirring is 30 to 80° C., and the time of the heating and stirring is 0.5 to 2 hours; And / or, in the step (A), the temperature of the heating and reflux is 105-110° C., and the time of the heating and reflux is 0.5-2 h; And / or, in the step (A), the alkylating agent comprises at least one of iodoalkanes, chloroalkanes, difatty sulfates or difatty carbonates; and / or, in the step (A), the molar ratio of the phenolic substances in the xylenol phenol oil fraction to the alkylating agent is 1:0.5-5; And / or, in the step (A), the temperature of the etherification reaction is 0 to 150° C., the time of the etherification reaction is 4 to 20 hours, and the pressure required for the etherification reaction is 0 to 1 MPa; And / or, in the step (A), after the etherification reaction is completed, the reaction is allowed to stand at 70-90° C. for stratification; And / or, in the step (A), the washing comprises: adding a sulfuric acid solution to the material layer for washing for 0.5 to 2 hours, then washing the obtained material layer in layers with water, and removing the washing water in layers; And / or, in the step (B), the pressure of the distillation treatment is -0.05 to 0.1 MPa, the reflux ratio of the distillation treatment is 20 to 25:1, the still residue is a mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole and other inevitable impurities, and the still residue is used for distillation to obtain a mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole; And / or, in the step (C), the amount of the concentrated sulfuric acid is 1 to 5% of the mass of the mixture of 2,3-dimethylanisole / m-p-ethylanisole / 3,5-dimethylanisole, and the mass of the isobutylene is 1 to 3 times the mass of the mixed m-p-methylanisole; And / or, in the step (C), the reaction temperature of introducing the isobutylene is 60-120° C., sampling and analysis are performed during the reaction, and a 6-tert-butyl-3-ethylanisole content of ≤0.5% indicates that the reaction is complete; an alkali solution is introduced to neutralize the pH to 7-8, and the reflux ratio of the vacuum distillation is 15-30:

1. And / or, the method further comprises step (F), wherein concentrated sulfuric acid is added to 4,6-di-tert-butyl-2,3-dimethylanisole, followed by neutralization with alkaline solution and separation by stratification, and the obtained material layer is subjected to vacuum distillation to obtain 2,3-dimethylanisole.

10. A method for synthesizing xylenol, characterized in that: The following steps are involved: Mix any one of p-ethylanisole, 2,5-dimethylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, and o-isopropylanisole obtained according to any one of claims 1 to 7 or any one of p-ethylanisole, 3,5-dimethylanisole, and 2,3-dimethylanisole obtained according to claim 8 or 9 with trimethylbenzene, heat to 130-150° C., drop 45-55% hydrobromic acid and react for 4-6 hours, cool the generated methyl bromide gas to -10° C. through a condenser and two cold traps and enter a bromoalkane storage tank, stop collecting bromoalkane after the reaction, collect the generated methyl bromide, then cool the reaction solution slightly to separate the hydrobromic acid aqueous solution, wash the solvent layer with water once and then separate the layers, combine the water layers to obtain a recovered hydrobromic acid solution, send the hydrobromic acid solution to other sections for concentration and recovery of 47% hydrobromic acid, perform vacuum distillation on the material layer to obtain xylenol, and recover trimethylbenzene for reuse; Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene; And / or, the amount of the trimethylbenzene used is 1 to 3 times the mass of the m-ethylanisole or p-ethylanisole; And / or, the molar ratio of hydrogen bromide to m-ethylanisole or p-ethylanisole in the hydrobromic acid is 1-3.