High-efficiency continuous catalytic distillation synthesis method of aryl methyl ether

Abstract

The invention relates to the technical field of compound synthesis, in particular to an efficient continuous catalytic distillation synthesis method of aryl methyl ether, which comprises the following steps: feeding a saturated nitrogen heterocyclic compound as a catalyst into a reactive distillation tower, continuously pumping a mixed raw material of aryl phenol and dimethyl carbonate into the reactive distillation tower, and carrying out methylation reaction under normal pressure; the generated reaction product aryl methyl ether, unreacted dimethyl carbonate, methanol and other reaction byproducts enter a first rectifying tower from the tower top of the reactive rectifying tower for separation, the reaction product aryl methyl ether is obtained at the tower bottom of the first rectifying tower, and tower top components enter a second rectifying tower for further separation; the saturated nitrogen heterocyclic compound is 1, 3-dimethyl-2-imidazolinone and / or 1, 3-dimethyl-tetrahydro-2-pyrimidinone, and the saturated nitrogen heterocyclic compound is 1, 3-dimethyl-2-imidazolinone and / or 1, 3-dimethyl-tetrahydro-2-pyrimidinone; the molar ratio of aryl phenol to dimethyl carbonate exceeds 1: 2; the raw materials are simple in variety, continuous production can be achieved, the product yield is at least 96%, and the product purity is at least 99%.

Description

Technical Field

[0001] The invention relates to the technical field of compound synthesis, and in particular to a method for efficiently and continuously catalytically distilling and synthesizing aryl methyl ether. Background Art

[0002] The structure of aryl methyl ether consists of an aromatic ring, a methyl group and a methoxy substituent, and can be a substitution product at different positions, such as p-methyl anisole, m-methyl anisole and other compounds.

[0003] Traditional production (CN1105974A) anisole adopts the method for the reaction of phenol and dimethyl sulfate, but dimethyl sulfate is a highly toxic substance, which seriously corrodes reaction equipment, produces a large amount of highly toxic waste water and solid waste, and the waste liquid and waste solid production is large, and environmental pollution is very serious, and the processing cost is higher, which is not conducive to the development as a core technology. Environmental protection requirements are constantly upgraded, and there is an urgent need to seek a more economical and environmentally friendly industrial synthesis method. Existing methyl iodide, dimethyl carbonate (DMC) and methanol etc. are also developed as methylating agents for the hydroxy etherification of phenolic compounds. The reaction process of part technology (CN110841663A) uses the lower toxic dimethyl carbonate as methylating agent, but is intermittent reaction, and the operating pressure is higher, and the reaction time is longer, and the products obtained yield is only 80% (optimum condition 95%), which is not conducive to industrialization. Summary of the invention

[0004] In order to solve the technical problems of low yield of aryl methyl ether and intermittent reaction being unfavorable for industrial production in the prior art, a highly efficient continuous catalytic distillation synthesis method of aryl methyl ether is provided. The raw materials of the present invention are simple, and only saturated nitrogen heterocyclic compounds are used as catalysts to methylate aryl phenol to obtain aryl methyl ether of corresponding structure. The method of the present invention can be continuously produced, and the product yield is at least 96%, and the product purity is at least 99%.

[0005] In order to achieve the above objectives, the present invention is implemented by the following technical solutions:

[0006] The invention discloses a highly efficient continuous catalytic distillation synthesis method for aryl methyl ether, comprising the following steps:

[0007] A saturated nitrogen heterocyclic compound is added as a catalyst into a reaction distillation tower, and a mixed raw material of aromatic phenol and dimethyl carbonate is continuously pumped into the reaction distillation tower to perform a methylation reaction under normal pressure;

[0008] The generated reaction product aryl methyl ether, the unreacted dimethyl carbonate, and the reaction by-products enter the first distillation tower from the top of the reaction distillation tower for separation, and the reaction product aryl methyl ether is obtained at the bottom of the first distillation tower;

[0009] Wherein, the saturated nitrogen heterocyclic compound is selected from one or more of 1,3-dimethyl-2-imidazolidinone (DMI) and 1,3-dimethyl-tetrahydro-2-pyrimidinone (DMPU);

[0010] Wherein, the molar ratio of the aromatic phenol to the dimethyl carbonate is controlled to be greater than 1:2.

[0011] Furthermore, the molar ratio of the aromatic phenol to the dimethyl carbonate is controlled to be 1:3-4.

[0012] Furthermore, the feed rate of the mixed raw material is controlled within the range of 200 mL / h to 1000 mL / h, and preferably the feed rate of the mixed raw material is 300 mL / h to 900 mL / h.

[0013] Furthermore, the amount of the saturated nitrogen heterocyclic compound is in the range of 2% to 6% of the total molar amount of the mixed raw material. Those skilled in the art can obtain the flow rates of the arylphenol and dimethyl carbonate based on the molar ratio of the arylphenol and dimethyl carbonate and the feed rate of the mixed raw material.

[0014] Preferably, the amount of the saturated nitrogen heterocyclic compound is 3.5% to 5.5% of the total molar amount of the mixed raw materials.

[0015] Further, the temperature of the methylation reaction is in the range of 180-230° C. Preferably, the temperature of the methylation reaction is 200-220° C.

[0016] Furthermore, the aromatic phenol is selected from phenol and methylphenol (the methyl substituent is at any position).

[0017] Furthermore, the reactor temperature of the reactive distillation tower ensures that the temperature of the methylation reaction is within the range of 180-230° C., the tower top temperature is 125-130° C., the reflux temperature is 40-50° C., and the recovery ratio is 2:3;

[0018] The bottom temperature of the first distillation tower is 1-10°C lower than the boiling point of the product aromatic methyl ether, the top temperature is in the range of 70-85°C, and the recovery ratio is 3:4.

[0019] Furthermore, the unreacted dimethyl carbonate and alcohol reaction byproducts are taken out from the top of the first distillation tower and enter the second distillation tower for separation, the unreacted dimethyl carbonate is taken out from the bottom of the second distillation tower and recycled into the mixed raw material for application, and the alcohol reaction byproducts are taken out and collected from the top of the second distillation tower, wherein the taken alcohol reaction byproducts contain a small amount of dimethyl carbonate;

[0020] The top temperature of the second distillation tower is in the range of 65-75°C.

[0021] Furthermore, the bottom flow of the reactive distillation tower is

[0022] Beneficial technical effects:

[0023] The present invention uses DMPU and / or DMI as catalysts, and allows aromatic phenol and dimethyl carbonate to undergo methylation reaction under normal pressure in a reaction distillation tower to obtain a mixture containing the corresponding product aromatic methyl ether, and subsequently, the aromatic methyl ether with a purity of at least 99% can be obtained by a single distillation purification, and the yield of the aromatic methyl ether is at least 96%. The present invention has high production efficiency, is environmentally friendly and is highly efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow chart of the highly efficient continuous catalytic distillation synthesis method of aryl methyl ether. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. All other embodiments obtained by ordinary technicians in this field without creative work based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Unless otherwise specifically stated, the numerical value set forth in these embodiments does not limit the scope of the present invention. The technology and method known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology and method should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values.

[0027] The experimental methods in the following examples without specifying specific conditions are usually measured in accordance with national standards; if there is no corresponding national standard, the method is carried out in accordance with the general standard requirements or general methods.

[0028] Other names for the reaction distillation tower include distillation tower reactor, distillation reactor, reaction distillation unit, reactor distillation tower, etc.

[0029] Example 1

[0030] This case is a highly efficient continuous catalytic distillation synthesis method for m-methyl anisole. The process flow diagram is shown in the figure. Figure 1 As shown, Figure 1 Where T1 represents a reactive distillation tower, T2 represents a first distillation tower, and T3 represents a second distillation tower, and the steps are as follows:

[0031] 500 g (3.901 mol) of DMPU was added to the reactor of the reaction distillation tower as a catalyst, and a mixed raw material of 2487 g (22.998 mol) of m-methylphenol and 6219 g (69.040 mol) of DMC was continuously pumped into the reactor of the reaction distillation tower, and the feed rate of the mixed raw material was controlled to be 600 mL / h ( Figure 1 The figure shows that the two raw materials are pumped in respectively, and the feed rates of the two raw materials can be obtained according to the controlled molar ratio of m-cresol to DMC and the feed rates of the two mixed raw materials. The methylation reaction is carried out at normal pressure. The temperature of the reactor of the reaction distillation tower is set to ensure that the temperature of the methylation reaction is 220°C, the tower top temperature is 125-130°C, the reflux temperature is 40-50°C, and the recovery ratio is 2:3; in the present invention, a certain amount of DMPU catalyst is pre-loaded in the reaction distillation tower, and the mixed raw materials continuously enter the reaction distillation tower. At a certain moment, the ratio of the catalyst to the mixed raw materials is much greater than 1, thereby rapidly generating a methylation reaction; the carbon dioxide waste gas generated during the reaction is discharged from the exhaust port of the reaction distillation tower, and the methylation reaction is carried out at normal pressure in turn;

[0032] The m-methylanisole produced during the methylation reaction reacts with the unreacted DMC and the methanol byproduct ( Figure 1 The first distillation tower is at normal pressure during purification, the bottom temperature of the first distillation tower is 173° C., the top temperature is in the range of 75-80° C., the recovery ratio is 3:4, and the reaction product m-methyl anisole is obtained at the bottom of the first distillation tower;

[0033] At the same time, the azeotrope of methanol and DMC is taken out from the top of the first distillation tower ( Figure 1 The dimethyl carbonate is extracted from the bottom of the second distillation tower and recycled into the mixed raw material for application to improve the reaction efficiency. Methanol is extracted and collected from the top of the second distillation tower. Figure 1 The methanol reaction byproduct P3 produced contains a small amount of dimethyl carbonate), and the raw materials are completely consumed (this is the first reaction).

[0034] Then, a mixed raw material of 2487g of m-methylphenol and 6219g of DMC was continuously pumped in again, and the reaction distillation tower was filled with DMPU from the first reaction (before the subsequent application begins, the DMPU catalyst can be taken out from the bottom of the reaction distillation tower and directly circulated into the kettle of the reaction distillation tower by a pump; or a catalyst feed tank can be added to make the DMPU catalyst taken out from the bottom of the tower circulated and pumped into the catalyst feed tank before entering the kettle of the reaction distillation tower), and the first application was carried out under the conditions of the above-mentioned first reaction to produce m-methylanisole, and so on.

[0035] In addition, if the DMPU catalyst is not loaded into the reactor of the reaction distillation tower in advance, Figure 1 As shown in , the DMPU catalyst is injected into the reaction distillation tower, flows to the bottom of the reaction distillation tower, and then is pumped out by a pump and pumped into the tower to realize the circulation of the DMPU catalyst in the reaction distillation tower.

[0036] The application results are shown in Table 1 below.

[0037] Table 1 Cycle application results

[0038] Catalyst application times Product purity wt% First reaction 99.50 First application 99.13 Second application 99.37 Fifth application 99.41 Tenth application 99.56

[0039] As shown in Table 1, no deactivation of the catalyst was found after multiple cycles of use of DMPU as a catalyst.

[0040] Example 2

[0041] This case is a highly efficient continuous catalytic distillation synthesis method of m-methyl anisole, which includes the following steps:

[0042] 500 g of DMPU was added to the reactor of the reaction distillation tower as a catalyst, and a mixed raw material of 2487 g of m-cresol and DMC was continuously pumped into the reactor of the reaction distillation tower, the molar ratio of m-cresol to DMC was 1:2-4, the feed rate of the mixed raw material was 300-1000 mL / h, and the methylation reaction was carried out under normal pressure. The reactor temperature of the reaction distillation tower was set to ensure that the methylation reaction temperature was 180-220 ° C, the tower top temperature was 125-130 ° C, the reflux temperature was 40-50 ° C, and the recovery ratio was 2:3

[0043] The m-methylanisole produced during the methylation reaction, the unreacted DMC, and the methanol reaction byproduct enter the first distillation tower from the top of the reactive distillation tower for purification. The first distillation tower is at normal pressure during purification. The bottom temperature of the first distillation tower is 173° C., the top temperature is in the range of 75-80° C., and the recovery ratio is 3:4. The reaction product m-methylanisole is obtained at the bottom of the first distillation tower.

[0044] At the same time, an azeotrope of methanol and DMC is extracted from the top of the first distillation tower and pumped into a subsequent second distillation tower for further separation and purification. The second distillation tower is at normal pressure during purification, and the top temperature of the second distillation tower is in the range of 65-75° C. Dimethyl carbonate is extracted from the bottom of the second distillation tower and recycled into the mixed raw material for application to improve the reaction efficiency. Methanol is extracted and collected from the top of the second distillation tower (a small amount of dimethyl carbonate will be contained in the extracted methanol reaction by-product) until the raw material is completely consumed.

[0045] The specific parameters and results are shown in Appendix 2.

[0046] Table 2 Parameters and results

[0047]

[0048] (Note: The data in the table are the results of the first reaction)

[0049] As can be seen from Table 2, the feed rate of the mixed raw material is in the range of 200 mL / h to 1000 mL / h, DMPU is used as the catalyst, the molar ratio of m-cresol to DMC is 1:3-4, the methylation reaction temperature is in the range of 180 to 220° C. (preferably the reaction temperature is 200-220° C.), the product yield is above 96 wt %, and the product purity is above 99 wt %.

[0050] Example 3

[0051] The synthesis process of this case is the same as that of Example 1, except that DMPU is replaced by DMI, the mixed raw materials are p-methylphenol and DMC, the amount of DMI is 620 g (5.431 mol), the amount of p-methylphenol is 2500 g (23.118 mol), and the amount of DMC is 6300 g (76.600 mol). The temperature setting of the bottom of the reaction distillation tower ensures that the temperature of the methylation reaction is 210°C.

[0052] The yield of the product p-methylanisole obtained in this case is 96.56wt% and the product purity is 99.30wt%.

[0053] Example 4

[0054] The synthesis process of this case is the same as that of Example 1, except that the mixed raw materials are o-methylphenol and DMC, the amount of DMPU is 600 g (4.681 mol), the amount of o-methylphenol is 2400 g (22.193 mol), and the amount of DMC is 6000 g (66.609 mol).

[0055] The yield of the product o-methylanisole obtained in this case is 96.60wt% and the product purity is 99.04wt%.

[0056] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A highly efficient continuous catalytic distillation synthesis method for aromatic methyl ethers, characterized in that: The steps include: A saturated nitrogen heterocyclic compound is added as a catalyst into a reaction distillation tower, and a mixed raw material of aromatic phenol and dimethyl carbonate is continuously pumped into the reaction distillation tower to perform a methylation reaction under normal pressure; The generated reaction product aryl methyl ether, the unreacted dimethyl carbonate, and the reaction by-products enter the first distillation tower from the top of the reaction distillation tower for separation, and the reaction product aryl methyl ether is obtained at the bottom of the first distillation tower; Wherein, the saturated nitrogen heterocyclic compound is selected from one or more of 1,3-dimethyl-2-imidazolidinone and 1,3-dimethyl-tetrahydro-2-pyrimidinone; Wherein, the molar ratio of the aromatic phenol to the dimethyl carbonate is controlled to be greater than 1:

2.

2. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 1, characterized in that: The molar ratio of the aromatic phenol to the dimethyl carbonate is controlled to be 1:3-4.

3. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 2, characterized in that: The feed rate of the mixed raw material is controlled within the range of 200 mL / h to 1000 mL / h.

4. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 2, characterized in that: The amount of the saturated nitrogen heterocyclic compound used is in the range of 2% to 6% of the total molar amount of the mixed raw materials.

5. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 4, characterized in that: The amount of the saturated nitrogen heterocyclic compound used is 3.5% to 5.5% of the total molar amount of the mixed raw materials.

6. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 2, characterized in that: The temperature of the methylation reaction is in the range of 180-230°C.

7. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 2, characterized in that: The aromatic phenol is selected from phenol and methylphenol.

8. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to any one of claims 1 to 7, characterized in that: The reactor temperature of the reactive distillation tower ensures that the temperature of the methylation reaction is within the range of 180-230°C, the tower top temperature is 125-130°C, the reflux temperature is 40-50°C, and the recovery ratio is 2:3; The bottom temperature of the first distillation tower is 1-10°C lower than the boiling point of the product aromatic methyl ether, the top temperature is in the range of 70-85°C, and the recovery ratio is 1:

4.

9. The method for efficiently and continuously synthesizing aryl methyl ether by catalytic distillation according to claim 8, characterized in that: The unreacted dimethyl carbonate and reaction byproducts are taken out from the top of the first distillation tower and enter the second distillation tower for purification, the unreacted dimethyl carbonate is taken out from the bottom of the second distillation tower and recycled into the mixed raw material for application, and the alcohol reaction byproducts are taken out and collected from the top of the second distillation tower; The top temperature of the second distillation tower is in the range of 65-75°C.

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