Method for producing o-methyl benzene alkyl ethers and 2, 6-dimethyl benzene alkyl ethers

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 o-methyl benzene alkyl ether and 2, 6-dimethyl benzene alkyl ether. The method for producing o-methyl benzene alkyl ether and 2, 6-dimethyl benzene alkyl ether, provided by the invention, comprises the following steps: (1) adding o-cresol post-fraction, a catalyst and an alkylating agent into a reactor for etherification reaction; and (2) after the etherification reaction is finished, carrying out standing layering, toluene extraction and washing treatment, carrying out normal pressure rectification on the obtained material layer to recover toluene for reuse, then carrying out reduced pressure rectification, and collecting o-methyl benzene alkyl ether, a middle fraction, 2, 6-dimethyl benzene alkyl ether and rectification kettle residues under chromatographic analysis. An alkylating agent is adopted to perform etherification reaction with phenol substances such as o-cresol and 2, 6-xylenol, boiling point difference can be increased, effective separation is performed, and then rectification is performed to obtain o-toluene alkyl ether and 2, 6-xylene alkyl ether products with good quality and high purity.

Description

Technical Field

[0001] The invention belongs to the technical field of coal coking and production and separation of organic chemical products, and specifically relates to a method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether. Background Art

[0002] When the o-cresol fraction obtained in the refining of crude phenol is distilled to produce 99.5% refined o-cresol, some o-cresol fractions containing various impurities will be produced. The main components are o-cresol, 2,6-dimethylphenol and a small amount of m-cresol. The impurities are mainly naphthalene, aniline, etc. The boiling points of m-cresol, o-cresol and 2,6-dimethylphenol are 202°C, 191°C and 203°C, respectively. The boiling points of phenolic substances are relatively small, and 2,6-dimethylphenol is highly volatile and difficult to separate from o-cresol at high concentrations. In addition, naphthalene, as an impurity, will azeotrope with o-cresol and is difficult to remove. The o-cresol fraction after distillation has many impurities and cannot be further purified from o-cresol, making its price much lower than 99.5% refined o-cresol and 99% 2,6-dimethylphenol. Therefore, the economic benefits of using the o-cresol fraction to replace refined o-cresol and pure 2,6-dimethylphenol to produce the corresponding alkyl ethers are very considerable.

[0003] Patent CN109942383A of Dalian Institute of Chemical Physics, Chinese Academy of Sciences, discloses a method for producing mixed ether by gas phase etherification of mixed phenol and methanol, which comprises at least the following steps: passing a mixture containing mixed phenol (phenol before crude phenol distillation at 220°C, various cresols, at least two of various xylenols) and methanol through a reaction zone containing an etherification catalyst to react and obtain ether. The method for producing mixed ether by mixed phenol and methanol uses mixed phenol and methanol as raw materials, the selectivity of etherification products can reach more than 98%, and the catalyst has good stability; and there is no equipment corrosion during the production process, and it is an environmentally friendly catalyst with good industrial application prospects. The reaction temperature used in the invention is above 250°C, and the reaction needs to be carried out at a low mixed phenol conversion rate to ensure high etherification selectivity (the conversion rate is generally 20-50%), with low single-pass yield, high energy consumption, and high production cost; at the same time, the reaction generates anisole, various methyl anisole, various dimethyl anisole, a small amount of trimethyl anisole, phenol, various cresols, various xylenols, and various trimethylphenols (methylation reaction also occurs on the benzene ring during etherification to generate phenol with one more methyl group; cresols and xylenols are easy to undergo transposition reaction at high temperature and in the presence of molecular sieve catalysts). Due to the high temperature, diphenyl ether and its homologues will inevitably be formed between phenols, and the composition is very complex: for example, the reaction of phenol, o-cresol, 2,6-dimethylphenol, and m-p-cresol with methanol will produce anisole, o-methylanisole, m-methylanisole, p-methylanisole, and 2,6-dimethylanisole. At the same time, various cresols, various dimethylphenols (2,6- / 2,4- / 2,5- / 2,3- / 3,5- / 3,4-dimethylphenol), and various trimethylphenols (mainly 2,4,6-trimethylphenol, 2,3,6-trimethylphenol, etc.) will also be produced. These phenolic products will Etherification generates 2,4- / 2,5- / 3,4- / 3,5- / 2,3-dimethylanisole, 2,4,6- / 2,3,6- / 2,3,5-trimethylanisole and other substances, so the reaction product is a mixture of the above substances; the boiling points of each substance are respectively m-p-methylanisole (boiling point at 175-176°C), o-methylanisole 171°C, 2,6-dimethylanisole 182°C (phenol 182°C), 2,4- / 2,5-dimethylanisole 190-192°C (o-cresol 191°C), 2,3- / 3,5-dimethylanisole 1 94~195℃ (o-cresol 191℃), 3,4-dimethylanisole 203℃ (m-cresol 201~202℃), 2,4,6-trimethylanisole 205.8℃ (m-cresol 201~202℃, o-ethylphenol 204.5℃), 2,3,5-trimethylanisole 220℃ (m-ethylphenol 218~219℃, 3,5-dimethylphenol 220℃), so it is very difficult to separate the etherified products from the phenolic products by distillation. Only the etherification catalyst with very good selectivity can extract the mixed anisole products at a low conversion rate.

[0004] Therefore, how to use the post-ortho-cresol fraction to prepare the corresponding alkyl ethers has received increasing attention. Summary of the invention

[0005] The present invention is made based on the inventor's discovery and understanding of the following facts and problems: when crude o-cresol or o-cresol fraction is distilled to obtain refined o-cresol to the rear section, a section containing impurities such as 2,6-dimethylphenol, benzene, aniline, etc. is inevitably produced, and these rear fractions containing a large amount of impurities cannot continue to extract high-content o-cresol. If they are to be mixed with low-grade cresol fractions, the high content of aniline and naphthalene will also cause the subsequent cresol to have a dark color, easy to change color and high neutral oil content.

[0006] The prior art method requires a low mixed phenol conversion rate to ensure high etherification selectivity, low single-pass yield, high energy consumption, and high production cost. In addition, the product composition generated by the method is very complex, and it is very difficult to separate the etherified product by distillation. Therefore, the method is difficult to promote and apply in industry.

[0007] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, the embodiment of the present invention provides a method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether, wherein the reaction conditions of the method are mild, the conversion rates of o-cresol and 2,6-dimethylbenzene alkyl ether can be controlled to be above 98% during the reaction, and only etherified products are generated, and the side reactions of alkylation and dealkylation on the benzene ring are basically not generated, the etherification selectivity is good, and high-purity o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether can be easily obtained by distillation separation.

[0008] A method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether according to an embodiment of the present invention comprises the following steps:

[0009] (1) adding the o-cresol fraction, a catalyst and an alkylating agent into a reactor to carry out an etherification reaction;

[0010] The catalyst comprises at least one of sodium methoxide, sodium ethoxide, sodium hydroxide, potassium hydroxide, pyridine and its homologues, and methylaminopyridine;

[0011] The alkylating agent includes at least one of iodoalkanes, chloroalkanes, di-fatty sulfates, and di-fatty carbonates;

[0012] (2) After the etherification reaction is completed, the mixture is allowed to stand and separated into a material layer and a water layer, toluene is added to the water layer for extraction to obtain a toluene layer and a separated water layer, and the toluene layer and the material layer are mixed and then washed to obtain a material layer;

[0013] (3) The material layer obtained in step (2) is first subjected to atmospheric distillation to recover toluene for reuse, and then subjected to vacuum distillation to collect o-methylbenzene alkyl ether, intermediate fraction, 2,6-dimethylbenzene alkyl ether and distillation still residue under chromatographic analysis.

[0014] The advantages and technical effects brought by the method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether of the embodiment of the present invention are as follows: 1. In the method of the embodiment of the present invention, the o-cresol fraction is reacted with an alkylating agent. Since impurities such as naphthalene and aniline are insoluble in alkaline substances and their aqueous solutions, impurities such as naphthalene and aniline can be removed during the reaction. The o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether obtained by distillation have good product quality and can be comparable to the products obtained by etherification of petrochemical o-cresol and 2,6-dimethylbenzene alkyl ether. Naphthalene can also be obtained while producing benzene alkyl ether materials; 2. The method of the embodiment of the present invention only produces etherified products, and basically does not produce The alkyl group on the raw benzene ring reacts with dealkylation, and the etherification selectivity is good. The conversion rates of o-cresol and 2,6-dimethylphenol in the reaction can be controlled to be above 98%, so it is easy to obtain high-purity o-toluene alkyl ether and 2,6-dimethylphenyl alkyl ether through distillation separation; 3. The method of the embodiment of the present invention adopts the o-cresol rear fraction with high impurity content, which is difficult to further purify o-cresol and has low price to replace refined o-cresol and pure 2,6-dimethylphenol to produce the corresponding alkyl ethers, and the economic benefit is very considerable; 4. The method of the embodiment of the present invention is simple and easy to implement, has good process operability, strong usability, remarkable economic benefit, and is convenient for popularization and application in industrial production.

[0015] In some embodiments, in step (1), the o-cresol post-fraction is obtained from the o-cresol fraction or the crude o-cresol distillation;

[0016] And / or, the o-cresol fraction comprises: 10-98% o-cresol, 1-60% 2,6-dimethylphenol, 0-5% aniline, 0-20% naphthalene, and 0-10% m-p-cresol, calculated in percentage by mass.

[0017] In some embodiments, in step (1), the temperature of the etherification reaction is 0 to 250° C., the pressure required for the etherification reaction is 0 to 10 MPa, and the time of the etherification reaction is 2 to 20 hours.

[0018] In some embodiments, in step (1), the amount of the catalyst added is 100 to 300 mol% of the phenolic substances in the o-cresol fraction;

[0019] And / or, the amount of the alkylating agent added is such that the molar ratio of the phenolic substances to the alkylating agent in the o-cresol fraction is 1:0.5-5.

[0020] In some embodiments, in the step (2), the washing treatment comprises: mixing the toluene layer and the material layer, adding sulfuric acid for washing, then washing the material layer by layers, removing the washing water by layers to obtain a material layer, combining the washing water from the sulfuric acid washing and the washing water to obtain washing water containing aniline sulfate;

[0021] Preferably, the obtained aniline sulfate washing water is added to a reaction kettle, 20-30% sodium hydroxide solution is added dropwise to neutralize to pH 7-8 under stirring, a water-insoluble solvent is added, the temperature is raised to 60-90° C. and stirred for 0.5-2 hours, the mixture is allowed to stand for stratification, the aniline solution is washed with water, and the washing water is removed by standing for stratification; the temperature is then raised to dehydrate and remove the solvent, and after the solvent is recovered, the material is transferred to a distillation tower, firstly vacuum distilled to recover the residual solvent, and then distilled to obtain more than 98% of aniline.

[0022] In some embodiments, the non-water-soluble solvent includes at least one of benzene, ketones, esters, halogenated alkanes, halogenated aromatic hydrocarbons, and ethers;

[0023] And / or, the amount of the water-insoluble solvent is 1 to 3 times the weight of aniline.

[0024] In some embodiments, in step (3), the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 15 to 25:1.

[0025] In some embodiments, in the step (3), the middle fraction comprises o-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether;

[0026] And / or, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, o-methylbenzene alkyl ether fraction, m-p-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether fraction, 2,6-dimethylbenzene alkyl ether and kettle residue.

[0027] In some embodiments, the m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140°C, and then hydrobromic acid is added for reaction. The brominated alkane gas generated by the reaction is cooled to -10°C to room temperature through a condenser and a cold trap and enters a brominated alkane storage tank. The reaction solution is then cooled and allowed to stand for stratification, and the hydrobromic acid aqueous solution is separated and recovered for reuse. The solvent layer is washed with water, and the separated material layer is first distilled and trimethylbenzene is recovered for reuse. Then, distillation is performed to obtain high-purity petrochemical-grade m-p-cresol of more than 99.5%, and the by-product brominated alkane can be reused as an alkylating agent. Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene, and the amount of the trimethylbenzene is 1-3 times the mass of the m-p-methylbenzene alkyl ether; the amount of the hydrobromic acid is 1-3 times the molar mass of the m-p-methylbenzene alkyl ether, and the concentration of the hydrobromic acid is 40-50%.

[0028] In some embodiments, in step (3), the distillation still residue comprises naphthalene and 2,6-dimethylbenzene alkyl ether, and the distillation still residue is added to a distillation still and subjected to vacuum distillation. The pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 10 to 15:1 to obtain 2,6-dimethylbenzene alkyl ether and naphthalene. DETAILED DESCRIPTION

[0029] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0030] A method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether according to an embodiment of the present invention comprises the following steps:

[0031] (1) adding the o-cresol fraction, a catalyst and an alkylating agent into a reactor to carry out an etherification reaction;

[0032] The catalyst comprises at least one of sodium methoxide, sodium ethoxide, sodium hydroxide, potassium hydroxide, pyridine and its homologues, and methylaminopyridine;

[0033] The alkylating agent includes at least one of iodoalkanes, chloroalkanes, di-fatty sulfates, and di-fatty carbonates;

[0034] (2) After the etherification reaction is completed, the mixture is allowed to stand and separated into a material layer and a water layer, toluene is added to the water layer for extraction to obtain a toluene layer and a separated water layer, and the toluene layer and the material layer are mixed and then washed to obtain a material layer;

[0035] (3) The material layer obtained in step (2) is first subjected to atmospheric distillation to recover toluene for reuse, and then subjected to vacuum distillation to collect o-methylbenzene alkyl ether, intermediate fraction, 2,6-dimethylbenzene alkyl ether and distillation still residue under chromatographic analysis.

[0036] In the method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether according to the embodiment of the present invention, the o-cresol fraction is reacted with an alkylating agent. Since impurities such as naphthalene and aniline are insoluble in alkaline substances and their aqueous solutions, the impurities such as naphthalene and aniline can be removed during the reaction. The o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether obtained by distillation have good product quality and can be comparable to the products obtained by etherification of petrochemical o-cresol and 2,6-dimethylbenzene alkyl ether. Naphthalene can also be obtained while producing benzene alkyl ether materials. The method according to the embodiment of the present invention only produces etherified products, and basically does not produce alkyl groups on the benzene ring and dealkylated groups. The alkyl reaction has good etherification selectivity, and the conversion rates of o-cresol and 2,6-xylenol in the reaction can be controlled to be above 98%, so high-purity o-toluene alkyl ether and 2,6-dimethylbenzene alkyl ether can be easily obtained through distillation separation; the method of the embodiment of the present invention adopts the o-cresol rear fraction with high impurity content, which is difficult to further purify o-cresol and has low price to replace refined o-cresol and pure 2,6-xylenol to produce corresponding alkyl ethers, and the economic benefit is very considerable; the method of the embodiment of the present invention is simple and easy to implement, has good process operability, strong usability, remarkable economic benefit, and is convenient for popularization and application in industrial production.

[0037] In some embodiments, preferably, in the step (1), the o-cresol post-fraction is obtained from the o-cresol fraction or the crude o-cresol distillation;

[0038] And / or, the o-cresol fraction comprises: 10-98% o-cresol, 1-60% 2,6-dimethylphenol, 0-5% aniline, 0-20% naphthalene, 0-10% m-p-cresol, in terms of mass percentage. Further preferably, the o-cresol fraction comprises: 50-95% o-cresol, 5-50% 2,6-dimethylphenol, 0-1% aniline, 0-10% naphthalene, 0-5% m-p-cresol, in terms of mass percentage.

[0039] In some embodiments, preferably, in step (1), the temperature of the etherification reaction is 0-250°C, the pressure required for the etherification reaction is 0-10 MPa, and the time of the etherification reaction is 2-20 hours. Further preferably, the temperature of the etherification reaction is 40-150°C, and the pressure required for the etherification reaction is 0-1 MPa.

[0040] In some embodiments, in step (1), the amount of the catalyst added is 100 to 300 mol% of the phenolic substances in the o-cresol fraction;

[0041] And / or, the amount of the alkylating agent added is such that the molar ratio of the phenolic substances in the o-cresol fraction to the alkylating agent is 1:0.5 to 5. More preferably, the amount of the alkylating agent added is such that the molar ratio of the phenolic substances in the o-cresol fraction to the alkylating agent is 1:1 to 3.

[0042] In some embodiments, preferably, in step (1), the catalyst is an aqueous sodium hydroxide solution; and / or the alkylating agent is dimethyl carbonate. Further preferably, the dimethyl carbonate is added to the reactor by dropwise addition, and the temperature during dropwise addition is not higher than 60°C.

[0043] In the embodiment of the present invention, the alkylating agent is further preferably dimethyl carbonate with low toxicity, which improves the safety of production operation, reduces poisoning behavior, and is beneficial to the health of operators.

[0044] In some embodiments, in the step (2), the static stratification is carried out at 70-90°C.

[0045] In some embodiments, preferably, in the step (2), the washing treatment comprises: mixing the toluene layer and the material layer, adding sulfuric acid for washing, then washing the material layer by water in layers, removing the washing water by layers to obtain a material layer, combining the washing water from the sulfuric acid washing and the washing water to obtain washing water containing aniline sulfate; preferably, adding the obtained aniline sulfate washing water to a reactor, adding dropwise 20-30% sodium hydroxide solution to neutralize to pH 7-8 under stirring, adding a non-water-soluble solvent, heating to 60-90° C. and stirring for 0.5-2 hours, standing to separate, washing the aniline solution with water, standing to separate to remove the washing water; then heating to dehydrate and desolventize, recovering the solvent, and transferring the material to a distillation tower, firstly performing vacuum distillation to recover the residual solvent, and then continuing distillation to obtain more than 98% of aniline.

[0046] In some embodiments, preferably, the non-aqueous solvent includes at least one of benzene, ketones, esters, halogenated alkanes, halogenated aromatic hydrocarbons, and ethers; and / or, the amount of the non-aqueous solvent is 1 to 3 times the weight of aniline. Further preferably, the non-aqueous solvent is toluene.

[0047] In some embodiments, preferably, in the step (3), the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 15 to 25:1.

[0048] In some embodiments, preferably, in the step (3), the middle fraction comprises o-methylbenzene alkyl ether, m / p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether;

[0049] And / or, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, o-methylbenzene alkyl ether fraction, m-p-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether fraction, 2,6-dimethylbenzene alkyl ether and kettle residue.

[0050] In some embodiments, preferably, the m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140°C, and then hydrobromic acid is added for reaction. The brominated alkane gas generated by the reaction is cooled to -10°C to room temperature through a condenser and a cold trap and enters a brominated alkane storage tank (-15°C to room temperature). After the reaction is completed, the collection of brominated alkanes is stopped, and then the reaction solution is cooled and allowed to stand for stratification, the hydrobromic acid aqueous solution is separated and recycled for reuse, the solvent layer is washed with water, and the separated material layer is recycled for trimethylbenzene in a distillation kettle for reuse, and then distilled to obtain more than 99.5% of m-p-cresol, and the by-product brominated alkanes are reused as alkylating agents. Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene, and the amount of the trimethylbenzene is 1 to 3 times the mass of the m-p-methylbenzene alkyl ether; the amount of the hydrobromic acid is 1 to 3 times the molar mass of the m-p-methylbenzene alkyl ether, and the concentration of the hydrobromic acid is 40 to 50%.

[0051] In the embodiment of the present invention, hydrobromic acid is reacted with m-p-methylbenzene alkyl ether to generate high-purity m-p-cresol, which can be used to produce high-grade photoresist and flame-retardant plasticizer tricresyl phosphate for aerospace, and has great economic benefits. In addition, hydrobromic acid can also be reacted with o-methylbenzene alkyl ether or 2,6-dimethylbenzene alkyl ether to generate high-purity o-cresol and high-purity 2,6-dimethylphenol, which are applied in industrial production.

[0052] In some embodiments, preferably, the reactor is a reactor or an enameled reactor.

[0053] In some embodiments, preferably, in the step (3), the distillation still residue comprises naphthalene and 2,6-dimethylbenzene alkyl ether, the distillation still residue is added to a distillation still, and vacuum distillation is performed, the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 10 to 15:1, to obtain 2,6-dimethylbenzene alkyl ether and naphthalene.

[0054] The technical solution of the present application is described in detail below in conjunction with specific embodiments.

[0055] Example 1

[0056] (1) 40,000 parts of the o-cresol fraction (in the examples, all are measured by weight) were added to the bottom of a distillation tower (the o-cresol fraction contained 75.1% o-cresol, 10.6% phenol, 4.1% 2,6-dimethylphenol, 1.7% naphthalene, 0.6% aniline, 7.6% m-cresol, and 0.3% others, all of which are measured by weight percentage in the examples), and vacuum distilled (vacuum degree -0.085 MPa, reflux ratio 10-15:1) to obtain 2367.9 parts of 95% phenol (composition: 95.4% phenol, 4.4% o-cresol, and 0.2% others), 1961.9 parts of mixed phenol (composition: 64.8% phenol, 34.7% o-cresol, and 0.5% others), and 2545.4 parts of the o-cresol fraction (composition: Phenol 15.4%, o-cresol 84.2%, others 0.4%), 99.5% refined o-cresol 18723.4 parts (composition: phenol 0.17%, o-cresol 99.51%, 2,6-xylenol 0.12%, aniline 0.07%, naphthalene 0.06%, others 0.07%), o-cresol back fraction 11197.4 parts (composition: o-cresol 74.4%, 2,6-xylenol 14.1%, aniline 2.0%, naphthalene 5.8%, m-p-cresol 3.5%, others 0.2%), distillation still residue 2956.7 parts (composition: o-cresol 8.2%, 2,6-xylenol 0.9%, aniline 0.17%, naphthalene 0.75%, m-p-cresol 88.55%, others 1.43%);

[0057] The distillation yield of 99.5% refined o-cresol is 62.1%, which is sold as a product; 95.4% phenol is sold outside; the o-cresol fraction is used for the distillation of refined o-cresol; the mixed phenol is used for the distillation of phenol; multiple batches of still residues are concentrated and used to extract different grades of m-p-cresol products; the o-cresol fraction is the raw material used in this embodiment.

[0058] (2) Add 2940 parts of the o-cresol fraction obtained in step (1) (74.4% o-phenol, 14.1% 2,6-dimethylphenol, 2.0% aniline, 5.8% naphthalene, 3.5% m-cresol, and 0.2% others) and 6750 parts of a 20% aqueous sodium hydroxide solution (the molar ratio of sodium hydroxide to phenolic substances in the o-cresol fraction is 1.37:1) into an enameled reactor, start stirring, and begin to dropwise add 1500 parts of dimethyl carbonate (the molar ratio of phenolic substances in the o-cresol fraction to dimethyl carbonate is 1:1.48), control the dropping temperature not to exceed 70°C, and the dropping time The reaction was continued for about 4 hours, and the reaction was kept warm for 10 hours under slightly boiling conditions (100°C) for sampling and analysis. The content of o-cresol was 0.26%. The temperature was lowered to 80°C and allowed to stand for stratification. The lower aqueous layer was separated and the aqueous layer was extracted once with 500 parts of toluene. The stratified aqueous layer was sent to a wastewater station. The toluene layer was mixed with the material layer, and 50 parts of sulfuric acid was added dropwise under 100 parts of water and stirred for 1 hour to remove aniline. The material layer was separated and washed with 100 parts of water. The washing water was completely removed by separation. The material layer was subjected to the following treatment. 309.8 parts of washing water were combined to obtain washing water containing aniline sulfate (containing aniline sulfate and 58.1 parts of aniline).

[0059] (3) The material layer obtained in step (2) was added to a distillation kettle, and 495.6 parts of toluene were recovered by atmospheric distillation for repeated use, and then vacuum distillation (-0.085 MPa) was changed to a reflux ratio of 15 to 20:1, and full reflux was performed for 1.5 hours for every 3 hours of distillation. Under chromatographic analysis, 2212.3 parts of 99.5% o-methyl anisole (99.51% of o-methyl anisole, 0.45% of m / p-methyl anisole, and 0.04% of others) and an intermediate fraction 4 were accurately collected. 06.7 parts (60.1% of o-methyl anisole, 24.7% of m- / p-methyl anisole, 14.9% of 2,6-dimethyl anisole, and 0.03% of others), 376.5 parts of 99.3% 2,6-dimethyl anisole (0.72% of m- / p-methyl anisole, 99.26% of 2,6-dimethyl anisole, and 0.02% of others), and 192.9 parts of the distillation still residue (including 169.6 parts of naphthalene and 23 parts of 2,6-dimethyl anisole).

[0060] (4) 3098 parts of washing water containing aniline sulfate from 10 batches (including 581 parts of aniline) were collected and added to a reaction kettle. A 20% sodium hydroxide solution was added dropwise under stirring to neutralize to pH 7-8. 1000 parts of recovered toluene and fresh toluene were added. The temperature was raised to 70° C. and stirred for 1 hour. The mixture was allowed to stand for stratification. The toluene solution was washed with 50 parts of water and allowed to stand for stratification to remove the washing water. The temperature was then raised to dehydrate and toluene, and 900 parts of toluene were recovered. The material was transferred to a distillation tower, and the toluene was first recovered by vacuum distillation. The distillation was then continued to obtain 531.4 parts of aniline with a concentration of 98.6%.

[0061] (5) 10 batches of distillation still residues were collected and added to a distillation still, and vacuum distillation (-0.085 MPa) was performed at a reflux ratio of 10 to 15:1 to obtain 216.8 parts of 99.7% 2,6-dimethylanisole and 1589.8 parts of 99% naphthalene.

[0062] The embodiment of the present invention produces: 99.5% o-methylanisole, 98.6% aniline, 99% naphthalene, 99.3% 2,6-dimethylanisole and an intermediate fraction, the intermediate fraction is incorporated into the distillation product of the next batch of etherification; o-methylanisole and 2,6-dimethylanisole are sold out.

[0063] Example 2

[0064] (1) The same as step (1) of Example 1.

[0065] (2) Add 2940 parts of the o-cresol fraction obtained in step (1) (74.4% o-cresol, 14.1% 2,6-dimethylphenol, 2.0% aniline, 5.8% naphthalene, 3.5% m-cresol, and 0.2% others) and 6750 parts of a 20% aqueous sodium hydroxide solution (the molar ratio of sodium hydroxide to phenolic substances in the o-cresol fraction is 1.37:1) to an enameled reactor, start stirring, and begin to dropwise add 1800 parts of dimethyl carbonate (the molar ratio of phenolic substances in the o-cresol fraction to dimethyl carbonate is 1.37:1). The dropping temperature is controlled not to exceed 60°C, the dropping time is about 4 hours, and after the dropping is completed, the reaction is kept warm under slightly boiling conditions (90°C) for 8 hours for sampling and analysis, o-cresol 0.08%, cooled to 80°C and allowed to stand for stratification, the lower water layer is separated, the water layer is sent to the waste water station, 100 parts of water are added to the material layer while stirring, 50 parts of sulfuric acid are added dropwise for washing for 1 hour to remove aniline, the material layer is separated, 100 parts of water are washed, the washing water is removed by stratification, the material layer is subjected to the following treatment, and the washing water is combined to obtain washing water containing aniline sulfate.

[0066] (3) The material layer obtained in step (2) was added to a distillation kettle, and vacuum distillation was performed (-0.085 MPa), with a reflux ratio of 20 to 25:1, and full reflux for 1.5 hours for every 4 hours of distillation. Under chromatographic analysis, 2308 parts of 99.7% o-methyl anisole (o-methyl anisole 99.71%, m- / p-methyl anisole 0.28%, and other 0.01%), 294.4 parts of the intermediate fraction (o-methyl anisole 49.1 %, m / p-methylanisole 36.3%, 2,6-dimethylanisole 14.5%, others 0.1%), 99.5% 2,6-dimethylanisole 400.3 parts (m / p-methylanisole 0.45%, 2,6-dimethylanisole 99.50%, others 0.05%), 184.5 parts of distillation still residue (including 167.6 parts of naphthalene, 15.8 parts of 2,6-dimethylanisole and 1.1 parts of others).

[0067] (4) The treatment of the washing water containing aniline sulfate is the same as step (4) of Example 1 to recover aniline.

[0068] (5) The treatment of the distillation still residue is the same as step (5) of Example 1, and 2,6-dimethylanisole and naphthalene are obtained by distillation.

[0069] (6) After combining multiple batches of intermediate fractions, 4000 parts (49.1% of o-methyl anisole, 36.3% of m- / p-methyl anisole, 14.5% of 2,6-dimethyl anisole, and 0.1% of others) were added to a high-efficiency rectification kettle and subjected to vacuum distillation to obtain 1227.4 parts of 99.2% o-methyl anisole (1217.6 parts of o-methyl anisole), 1101.8 parts of o-methyl anisole fraction (65.29% of o-methyl anisole, 34.65% of m-p-methyl anisole), and 786.6 parts of m-p-methyl anisole. (1.35% o-methylanisole, 97.71% m-methylanisole, 0.89% 2,6-dimethylanisole), 429.6 parts of m-methylanisole fraction (64.34% m-methylanisole, 35.61% 2,6-dimethylanisole), 292.4 parts of 99.38% 2,6-dimethylanisole (0.48% m-methylanisole, 99.38% 2,6-dimethylanisole), and 126.6 parts of still residue (124.2 parts of 2,6-dimethylanisole).

[0070] (7) 500 parts of m-p-methylanisole (1.35% of o-methylanisole, 97.71% of m-p-methylanisole, and 0.89% of 2,6-dimethylanisole) and 500 parts of mixed trimethylbenzene were added to the reaction kettle, the temperature was raised to 120° C., 47% hydrobromic acid was added dropwise for reaction, and the methyl bromide gas generated by the reaction was cooled to −10° C. by a condenser and two cold traps and then entered into a bromoalkane storage tank (−15° C.). After the reaction was completed, the collection of bromoalkane was stopped, and a total of 1,400 parts of 47% hydrobromic acid was added dropwise, and 381.4 parts of methyl bromide were collected, with a yield of 98.1%. The reaction solution was then cooled slightly and hydrogen was separated. Bromic acid aqueous solution, the solvent layer is washed once with 50 parts of water, the layers are separated, the water layers are combined, and 1094.1 parts of 28.1% hydrobromic acid solution are obtained (47% of the hydrobromic acid is recovered by heating), 486.3 parts of trimethylbenzene are recovered in the material layer distillation kettle and reused, and then distilled to obtain 41.3 parts of the fore fraction (78.9% of meta-cresol, 12.6% of o-cresol, 8.3% of 2,6-xylenol), 333.8 parts of high-purity meta-cresol (99.82% of meta-cresol, 0.09% of o-cresol, 0.06% of 2,6-xylenol), and 69.8 parts of the kettle residue (including 61.2 parts of meta-cresol).

[0071] The embodiment of the present invention produces: 99.7% o-methyl anisole, 99.5% 2,6-dimethyl anisole and high-purity m-p-cresol, and the o-methyl anisole and 2,6-dimethyl anisole products are sold outside.

[0072] Example 3

[0073] (1) The same as step (1) of Example 1.

[0074] (2) Add 2940 parts of the o-cresol fraction obtained in step (1) (74.4% o-cresol, 14.1% 2,6-xylenol, 2.0% aniline, 5.8% naphthalene, 3.5% m-cresol, and 0.2% others) and 5500 parts of a 20% aqueous sodium hydroxide solution (the molar ratio of sodium hydroxide to phenolic substances in the o-cresol fraction is 1.13:1) to a high-pressure reactor, start stirring, and pressurize 2800 parts of methyl bromide (the molar ratio of phenolic substances in the o-cresol fraction to methyl bromide is 1:0.83). Close the container, raise the temperature to 90°C, and keep it warm for reaction. Sampling and analysis should be carried out every 6 hours, and the o-cresol 0.13% is qualified. 452.8 parts of methyl bromide are recovered by pressure relief and reused, and the temperature is lowered to 60°C and allowed to stand for stratification. 7493 parts of the lower water layer (containing 2533.2 parts of sodium bromide, accounting for 33.8%) are separated, and the water layer is sent to recover bromine or hydrobromic acid (or sodium bromide). 100 parts of water are added to the material layer, and 50 parts of sulfuric acid are added dropwise while stirring to wash for 1 hour to remove alkaline substances such as aniline. The material layer is separated, and 100 parts of water are washed for the material layer. The washing water is removed by separation, and the material layer is subjected to the following treatment. The washing water is combined to obtain washing water containing aniline sulfate.

[0075] (3) The material layer obtained in step (2) is added to a distillation kettle, and distilled under reduced pressure (-0.085 MPa), with a reflux ratio of 20 to 25:1, and full reflux for 2 hours for every 4 hours of distillation. Under chromatographic analysis, 2326.2 parts of 99.80% o-methyl anisole (2321.6 parts of o-methyl anisole, 4.4 parts of m- / p-methyl anisole, and 0.2 parts of others) and 263.9 parts of the intermediate fraction (124. 2 parts, m / p-methyl anisole 107.0 parts, 2,6-dimethyl anisole 32.4 parts, others 0.3 parts), 99.48% 2,6-dimethyl anisole 406.7 parts (m / p-methyl anisole 1.9 parts, 2,6-dimethyl anisole 404.6 parts, others 0.2 parts), distillation still residue 181.1 parts (including naphthalene 168.1 parts, 2,6-dimethyl anisole 11.7 parts, others 1.3 parts).

[0076] Steps (4) to (7) are the same as steps (4) to (7) of Example 2: washing water containing aniline sulfate recovers aniline; multiple batches of residual naphthalene in the distillation still are combined and then distilled; the intermediate fractions are concentrated and used for secondary distillation to extract high-content m-p-methylanisole, and the high-content m-p-methylanisole is used to produce 99.5% high-purity m-p-cresol.

[0077] (8) The 33.8% sodium bromide aqueous solution produced in step (2) is sold to a bromine production enterprise to recover bromine or is distilled by acid addition to produce a 45% or higher grade hydrogen bromide aqueous solution, and the hydrogen bromide aqueous solution is reused in the step of demethylating m-p-anisole to produce high-purity m-p-cresol and methyl bromide.

[0078] The embodiment of the present invention produces: 99.80% of o-methyl anisole, 99.48% of 2,6-dimethyl anisole and 99.5% of high-purity m-p-cresol, and the o-methyl anisole and 2,6-dimethyl anisole products are sold outside.

[0079] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0080] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether, characterized in that: The steps include: (1) adding the o-cresol fraction, a catalyst and an alkylating agent into a reactor to carry out an etherification reaction; The catalyst comprises at least one of sodium methoxide, sodium ethoxide, sodium hydroxide, potassium hydroxide, pyridine and its homologues, and methylaminopyridine; The alkylating agent includes at least one of iodoalkanes, chloroalkanes, di-fatty sulfates, and di-fatty carbonates; (2) After the etherification reaction is completed, the mixture is allowed to stand and separated into a material layer and a water layer, toluene is added to the water layer for extraction to obtain a toluene layer and a separated water layer, and the toluene layer and the material layer are mixed and then washed to obtain a material layer; (3) The material layer obtained in step (2) is first subjected to atmospheric distillation to recover toluene for reuse, and then subjected to vacuum distillation to collect o-methylbenzene alkyl ether, intermediate fraction, 2,6-dimethylbenzene alkyl ether and distillation still residue under chromatographic analysis.

2. The method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether according to claim 1, characterized in that: In the step (1), the o-cresol rear fraction is obtained by distilling the o-cresol fraction or the crude o-cresol; And / or, the o-cresol fraction comprises: 10-98% o-cresol, 1-60% 2,6-dimethylphenol, 0-5% aniline, 0-20% naphthalene, and 0-10% m-p-cresol, calculated in percentage by mass.

3. The method for producing o-methylbenzene alkyl ether and 2,6-xylyl alkyl ether according to claim 1, characterized in that: In the step (1), the temperature of the etherification reaction is 0 to 250° C., the pressure required for the etherification reaction is 0 to 10 MPa, and the time of the etherification reaction is 2 to 20 hours.

4. The method for producing o-methylbenzene alkyl ether and 2,6-xylyl alkyl ether according to claim 1, characterized in that: In the step (1), the amount of the catalyst added is 100 to 300 mol% of the phenolic substances in the o-cresol fraction; And / or, the amount of the alkylating agent added is such that the molar ratio of the phenolic substances to the alkylating agent in the o-cresol fraction is 1:0.5-5.

5. The method for producing o-toluene alkyl ether and 2,6-dimethylbenzene alkyl ether according to claim 1, characterized in that: In the step (2), the washing treatment comprises: mixing the toluene layer and the material layer, adding sulfuric acid for washing, then washing the material layer by layers, removing the washing water by layers to obtain the material layer, combining the washing water from the sulfuric acid washing and the washing water to obtain the washing water containing aniline sulfate; Preferably, the obtained aniline sulfate washing water is added to a reaction kettle, 20-30% sodium hydroxide solution is added dropwise to neutralize to pH 7-8 under stirring, a water-insoluble solvent is added, the temperature is raised to 60-90° C. and stirred for 0.5-2 hours, the mixture is allowed to stand for stratification, the aniline solution is washed with water, and the washing water is removed by standing for stratification; the temperature is then raised to dehydrate and remove the solvent, and after the solvent is recovered, the material is transferred to a distillation tower, firstly vacuum distilled to recover the residual solvent, and then distilled to obtain more than 98% of aniline.

6. The method for producing o-toluene alkyl ether and 2,6-dimethylbenzene alkyl ether according to claim 5, characterized in that: The non-water-soluble solvent includes at least one of benzene, ketones, esters, halogenated alkanes, halogenated aromatic hydrocarbons, and ethers; And / or, the amount of the water-insoluble solvent is 1 to 3 times the weight of aniline.

7. The method for producing o-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether according to claim 1, characterized in that: In the step (3), the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 15 to 25:

1.

8. The method for producing o-methylphenyl alkyl ether and 2,6-dimethylphenyl alkyl ether according to claim 1, characterized in that: In the step (3), the middle fraction includes o-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether and 2,6-dimethylbenzene alkyl ether; And / or, the middle fraction is subjected to vacuum distillation to obtain o-methylbenzene alkyl ether, o-methylbenzene alkyl ether fraction, m-p-methylbenzene alkyl ether, m-p-methylbenzene alkyl ether fraction, 2,6-dimethylbenzene alkyl ether and kettle residue.

9. The method for producing o-methylphenyl alkyl ether and 2,6-dimethylphenyl alkyl ether according to claim 7, characterized in that: The m-p-methylbenzene alkyl ether and trimethylbenzene are added to a reactor, the temperature is raised to 110-140° C., and then hydrobromic acid is added for reaction. The bromoalkane gas generated by the reaction is cooled to -10° C. to room temperature through a condenser and a cold trap and enters a bromoalkane storage tank. Then, the reaction solution is cooled and allowed to stand for stratification, and the hydrobromic acid aqueous solution is separated and recovered for reuse. The solvent layer is washed with water, and the separated material layer is first distilled and trimethylbenzene is recovered for reuse. Then, more than 99.5% of m-p-cresol is obtained by distillation, and the by-product bromoalkane is reused as an alkylating agent. Preferably, the trimethylbenzene includes at least one of 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene and 1,3,5-trimethylbenzene, and the amount of the trimethylbenzene is 1-3 times the mass of the m-p-methylbenzene alkyl ether. The amount of the hydrobromic acid is 1-3 times the molar mass of the m-p-methylbenzene alkyl ether, and the concentration of the hydrobromic acid is 40-50%.

10. The method for producing o-methylphenyl alkyl ether and 2,6-dimethylphenyl alkyl ether according to claim 1, characterized in that: In the step (3), the distillation still residue comprises naphthalene and 2,6-dimethylbenzene alkyl ether, and the distillation still residue is added to a distillation still and subjected to vacuum distillation, wherein the pressure of the vacuum distillation is -0.05 to -0.1 MPa, and the reflux ratio is 10 to 15:1, to obtain 2,6-dimethylbenzene alkyl ether and naphthalene.