CN111233678A - Improved method for preparing diphenyl ether derivative by micro-channel process - Google Patents

Abstract

The invention relates to a method for preparing diphenyl ether derivatives by an improved microchannel process, which comprises the steps of preparing a slurry by using a raw material containing diphenyl ether, a palladium-carbon catalyst and a solvent according to a certain proportion, and continuously inputting the slurry into a microchannel reactor by a slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; wherein in the slurry as configured, a diluted alkaline substance is further mixed in an amount of about 0.1 wt% to 2.0 wt% based on the total weight of the entire slurry. According to the process route of the invention, the continuous production performance of diphenyl ether derivatives can be further improved, and the reaction steps of the process can be smoothly carried out in a long-time continuous production state. And according to the process of the invention, existing production devices and equipment of the existing industrial or laboratory grade do not need to be changed.

Description

Improved method for preparing diphenyl ether derivative by micro-channel process

Technical Field

The invention relates to and provides a preparation process of chemical raw materials, and particularly relates to a preparation method of organic chemical raw materials (diphenyl ether and derivatives thereof). More particularly, the present invention relates to a process for preparing diphenyl ether derivatives (e.g., 4' -diaminodiphenyl ether) by a microchannel process.

Background

Diphenyl ether derivative is an important chemical raw material, and can be used not only as a raw material of a terminal chemical product, but also in a plurality of fields such as biology, medicine and the like. Wherein 4,4 '-diaminodiphenyl ether is abbreviated as 4,4' -ODA (similarly, 4 '-diaminodiphenyl ether; 4,4' -diaminodiphenyl ether p-aminodiphenyl ether; 4, 4-diaminodiphenyl ether; 4,4 '-oxydianiline; 4,4' -diaminodiphenyl ether), can be used as one of the most important raw materials of polyimide materials. Polyimide is used as an excellent engineering plastic material and has wide application in the fields of aerospace, microelectronics, machining and the like.

There are numerous methods for synthesizing, preparing, purifying and/or improving the preparation of diphenyl ether derivative compounds. Usually with a batch hydrogenation kettle, and a process for the preparation of 4,4' -diaminodiphenyl ether by continuous hydrogenation (e.g. the microchannel process). The continuous method such as microchannel has the advantages of continuous reaction, shortened reaction time, obviously improved reaction efficiency, easy purification and the like, and is a promising manufacturing process of the diaminodiphenyl ether.

For example, chinese patent application 201910715813.1 provides a method for preparing 4,4' -diaminodiphenyl ether using a microchannel continuous flow reactor. The process indicates that the high-purity diaminodiphenyl ether can be prepared by the following similar method: preparing 4,4' -dinitrodiphenyl ether, a palladium-carbon catalyst and a solvent into slurry according to a certain proportion, and pumping the slurry into a microchannel reactor through a slurry pump; simultaneously introducing hydrogen with a certain proportion into the microchannel reactor through a hydrogen feeding system; reacting for 10-180s at 50-200 ℃ under the pressure of 0.3-1.8 MPa, separating from the microchannel reactor, feeding into a material receiving kettle, filtering to remove the palladium-carbon catalyst, removing most of the solvent in vacuum, performing primary recrystallization, separating out solids, performing secondary recrystallization, and separating and drying to obtain the 4,4' -diaminodiphenyl ether.

However, the inventors of the present invention found in practice that, in the case of a 4,4' -diaminodiphenyl ether system, although the discontinuous reaction is more continuous in practice, the phenomenon of flow choking and clogging of the microchannel occurs after the reaction has continued for a certain period of time (for example, more than 0.5 hour), or longer, even if the microchannel reactor of a different brand or a manufacturer is replaced.

In fact, the problem of clogging of microchannel reactors has been improved on a targeted basis by researchers and scholars. However, the existing methods are mainly directed to the improvement of the structure itself of the channel reactor in general. For example, chinese patent CN206474136U provides a microchannel reactor, which relates to: the device is including dismantling mainboard and the apron that the lid closed, the mainboard with the one side that the lid closed of apron is provided with concave to microchannel in the mainboard, microchannel is including feed channel, hybrid channel, reaction channel and the discharging channel who communicates in proper order, feed channel and discharging channel extend to the border of mainboard, feed channel's quantity is one at least, reaction channel includes a plurality of similar rhombus's that communicate in proper order two-way passageway, an angle intercommunication next rhombus passageway of last rhombus passageway. This patent design utilizes a specially shaped channel configuration and shape to avoid plugging and accumulation of solid matter.

However, under the system of the present inventors, the replacement of the microchannel apparatus requires the rearrangement of the entire reaction system and parameters, which is disadvantageous for the advancement of industrial production. In addition, under the working condition of long-time reaction of some systems, the problems of reduction and blockage of the reaction efficiency of the microchannel reaction device can be caused to a certain extent.

For another example, chinese patent CN105363476A proposes a method for regenerating and utilizing palladium/carbon catalyst. However, the method aims at solving the technical problems of catalyst poisoning and reduction of reaction efficiency caused by the catalyst poisoning, and is not the problem faced by the application of the palladium/carbon catalyst in a microchannel reaction device.

It is therefore highly desirable to provide an improved microchannel process for the preparation of diphenyl ether derivatives, particularly 4,4' -diaminodiphenyl ether.

The applicant hereby states that the present invention may incorporate some or all of the technical solutions represented by the patent documents mentioned in this background section, and may impose further improvements thereto, as long as such solutions or improvements are known to those skilled in the art upon reading the present invention.

Disclosure of Invention

In view of the above-described related art, it is an aspect of the present invention to provide a method for preparing a diphenyl ether derivative suitable for an improved microchannel process, which solves the disadvantages of one or more of the above-described problems. In particular, the present inventors have unexpectedly found that the continuous productivity for the preparation of diphenyl ether derivatives can be further improved by the process route of the present invention, and the reaction steps of the process can be smoothly carried out in a continuous production state for a long period of time without hindrance. And according to the process of the invention, existing production devices and equipment of the existing industrial or laboratory grade do not need to be changed.

According to one aspect of the present invention, there is provided a method for preparing diphenyl ether derivatives by an improved microchannel process, the method comprising preparing a slurry comprising a diphenyl ether raw material, a palladium-on-carbon catalyst, and a solvent in a certain ratio, continuously feeding the slurry into a microchannel reactor by a slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; wherein, in the slurry configured, diluted alkaline substance is further mixed in an amount of about 0.1 wt% to 2.0 wt% based on the total weight of the entire slurry. The diphenyl ether derivative may refer to a compound containing a diphenyl ether group, and may be 4,4' -diaminodiphenyl ether in embodiments.

As will be described in more detail below, the inventors have unexpectedly found that the addition of a small amount of an alkaline substance to a process for producing a diphenyl ether derivative in a microchannel can effectively alleviate and solve the clogging and stagnation of solid substances (mainly, solid catalyst) in the microchannel reactor, and enhance and improve the continuous productivity of the microchannel reactor. In the process, a small amount of alkaline substance, particularly diluted alkaline substance, is added on the basis of the existing slurry material composition, so that the continuous production problem of the microchannel reactor concerned by the invention can be improved and solved.

In an alternative, the dilute alkaline material selected comprises a dilute sodium bicarbonate solution.

The sodium bicarbonate solution is preferably selected and used in the test process, mainly considering that the sodium bicarbonate solution has relatively weak alkalinity, the mass concentration is convenient to control, the commercially available high-purity product is more easily obtained, and the preparation of stable process parameters is facilitated. Furthermore, tests have found that the degree of reaction between the more dilute sodium bicarbonate solution and the possible target products is lower, with little or no effect on the purity of the reaction products and the main reaction process, and also with a reduced risk of poisoning the catalyst.

In an alternative embodiment, the diluted alkaline substance is a sodium bicarbonate solution with a mass fraction of 1 wt% to 10 wt%, preferably a sodium bicarbonate solution with a mass fraction of 1 wt% to 5 wt%, most preferably a sodium bicarbonate solution with a mass fraction of 1 wt% to 2 wt%, in the method for preparing a diphenyl ether derivative according to the microchannel process of the present invention.

It has been shown by research and experimental results that it seems that acidic/basic species may cause a decrease in catalyst efficiency and even cause catalyst poisoning such that the main reaction of the carbon/palladium catalyst does not proceed. However, the inventor unexpectedly found through experiments that the use of a small amount of sodium bicarbonate solution in the microchannel process not only has a limited effect on the main reaction, but also solves the possible blockage phenomenon of the microchannel process. However, when the basic substance is high, there arise problems that the reaction end product is lowered and the reaction efficiency is lowered. Presumably, the catalyst performance may be lowered by the influence of a high concentration of alkali, and the reaction end product may react with a high concentration of alkali substance.

In a preferred embodiment, the diphenyl ether derivatives synthesized by the present invention include or are 4,4' -diaminodiphenyl ether; and wherein the diphenyl ether starting material comprises or is 4,4' -dinitrodiphenyl ether.

According to an alternative, the palladium on carbon catalyst mass is from about 0.05% to about 25%, preferably 10 to 20%, 12% to 18%, most preferably 15% to 18% of the diphenyl ether starting material.

According to the technical scheme of the invention, the efficiency can be improved and further improved, and one reason is that the proportion of the catalyst in the reaction process can be further improved. In the case of conventional microchannel reaction processes, the typical palladium on carbon catalyst mass does not exceed 10% wt of the total reactant system or corresponding diphenyl ether derivative starting material in order to reduce the risk of solid material clogging the reaction path. According to the process of the present invention, the mass fraction of the catalyst used can be further increased, which may further improve the overall reaction rate and efficiency.

For a particular embodiment of the invention, the method of the invention may comprise the steps of:

preparing 4,4' -dinitrodiphenyl ether, a palladium-carbon catalyst and a solvent (preferably alcohols, and also can be amide or aromatic solvent) into slurry, and mixing sodium bicarbonate solution which accounts for about 0.1-2 wt% of the total weight of the whole slurry and has the mass fraction of 1-2 wt% into the prepared slurry; after the mixture is uniformly mixed, continuously pumping the mixture into a micro-channel reactor by using a slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; reacting at the pressure of 0.3-1.8 MPa and the temperature of 50-200 ℃ to separate from the microchannel reactor and enter a material receiving kettle, filtering to remove the palladium-carbon catalyst, removing the solvent in vacuum, then carrying out primary recrystallization, separating out solids, then carrying out secondary recrystallization, and separating and drying to obtain the product mainly comprising 4,4' -diaminodiphenyl ether. The solution of the invention also contemplates the use of dilute strongly basic substances such as sodium hydroxide and its solutions.

In a further alternative, optionally, after filtering to remove the palladium on carbon catalyst, a step of washing the product with deionized water is included before removing the solvent in vacuo. The stripping step helps to remove a small amount of alkaline substances contained in the system.

In an alternative scheme, the mass ratio of the noble metal in the palladium-carbon catalyst is 1-10%, and preferably 3-5%. If a commercially available catalyst is used, a 5 wt% palladium on carbon or a 10 wt% palladium on carbon catalyst may optionally be used.

In a further alternative scheme, the molar ratio of the 4,4' -dinitrodiphenyl ether to the hydrogen is 1: 6.01-1: 6.6.

The microchannel reactor of the present invention may be used with existing microchannel processes, preferably using microchannel parameters and equipment set by the inventors. In the apparatus:

the micro-channel continuous flow reactor is formed by connecting 1-20 micro-channel reactor modules;

the depth (or width and diameter) of the inner channel of the microchannel reactor is 100 mu m-10 mm.

The liquid holdup of the microchannel reactor is 5-2500 mL;

and, optionally,

the module structure of the microchannel reactor is one of a micro-tubular structure, a groove-shaped structure, a T-shaped structure, a spherical baffle structure, a water drop-shaped structure, an umbrella-shaped structure or a heart-shaped structure; the microchannel reactor is made of one of special glass, silicon carbide, sapphire, corrosion-resistant alloy and fluoropolymer.

The technical solutions and advantages of the present invention will be explained and explained in more detail below with reference to specific embodiments. It should be understood that the contents presented in the description and the detailed description are only for more clearly illustrating the technical solutions and the advantages of the present invention, and do not limit the protection scope of the present invention. In the present invention, the numbers and ratios not specified are mass or mass percentage ratios of substances/materials/products. When compounds or materials expressed by other units/names are used, the specification makes corresponding specific description thereof.

On the basis of the disclosure of the specification, a person skilled in the art can modify the technical solution according to various reasonable changes, and the modified technical solution should be understood as being included in the protection scope of the invention as long as the person does not depart from the spirit of the invention.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosed embodiments and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the principles of the disclosure and not to limit the disclosure.

FIG. 1 is a front view and a cross-sectional view of a microchannel reactor assembly according to one embodiment of the invention;

fig. 2 is a cross-sectional view of an angular channel of a microfluidic channel of the present invention taken along an axial direction.

Detailed Description

The present invention is described in more detail below to facilitate an understanding of the invention.

Before the description of the specific embodiments, the essential fact that part of the main raw materials used have been sourced is described in the present specification. It should be noted that the sources of the raw materials described in the embodiments herein are not limiting, and those skilled in the art can select appropriate raw materials and testing equipment to perform the relevant tests and obtain the corresponding results according to the teaching and teaching of the present invention, and for raw materials which do not describe a specific manufacturer or route, those skilled in the art can select raw materials as the reaction starting materials to meet the corresponding requirements according to the disclosure and requirements of the present specification. It will also be understood from the disclosure of the present specification that the starting materials for the synthesis of a portion of the compounds are from the first products of synthesis in some of the preceding steps.

The method mainly comprises the following steps:

the microchannel device adopts a microchannel continuous flow reactor provided in Chinese patent application 201810774661.8 and an improved reactor based on the microchannel continuous flow reactor provided in 201810774661.8; alternatively, Advanced-

G1 series carbon silicon ceramic reactors.

The microscopic test apparatus used for the experiment was from a scanning electron microscope of JSM500 series manufactured by JEOL corporation of Japan.

The 4,4' -dinitrodiphenyl ether is a commercial product from Shenzhen Rigji Tech Co., Ltd., purity is 99%; sodium bicarbonate and solution products were prepared from commercial products of the marching chemical industry, texas. The pressure hydrogen is provided by Shandongchang gas Co. The palladium-carbon catalyst is 5 wt% Pd/C and 10 wt% Pd/C provided by Talida technologies, Inc., Suzhou.

Experiment 1: synthesis process of 4,4' -diaminodiphenyl ether

Preparing 4,4 '-dinitrodiphenyl ether, a palladium-carbon catalyst (5 wt% Pd/C) and a solvent (DMF) into a slurry (the mass ratio of the 4,4' -dinitrodiphenyl ether to the solvent DMF is 1: 2.5), and mixing sodium bicarbonate solution which accounts for about 0.1 wt% to 2 wt% of the total weight of the whole slurry and has the mass fraction of 1 wt% to 2 wt% into the prepared slurry; after uniform mixing, continuously pumping the mixture into a microchannel reactor by using a slurry pump, and continuously introducing reactants for 3-60 min; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; controlling the gas transmission pressure to be 0.3-1.8 MPa, controlling the hydrogen flow to be 3-5 liters/min, controlling the temperature to be 50-200 ℃ for reaction until the gas is separated from the microchannel reactor and enters a material receiving kettle, and monitoring the pressure change inside the microchannel reactor in the reaction process; detecting, filtering and removing the palladium-carbon catalyst, removing the solvent in vacuum, then carrying out primary recrystallization, separating out solids, then carrying out secondary recrystallization according to the purity requirement, and separating and drying to obtain the product mainly comprising 4,4' -diaminodiphenyl ether. Optionally, the resulting product is washed one or more times with deionized water. The specific experimental parameters are shown in the following table

Table 1: experiment 1-Synthesis Process of 4,4' -diaminodiphenyl ether of the invention (Main Experimental parameters)

As can be seen from the above series of experiments, examples 1-3 can be continuously run in a microchannel reactor under continuous reaction conditions for a long time (more than 30 minutes to 2 hours). In contrast, in the condition of comparative example 1, when the time for continuously feeding the reaction material was increased to 30min or more, there was a phenomenon that the internal pressure of the pipe in the reactor was increased and the outlet flow rate was decreased. This phenomenon is considered to cause a deterioration in fluidity of the liquid phase in the pipe, and a pipe clogging phenomenon may occur in the pipe.

Here, the inventors conducted an in-depth analysis of the interior of the microflow reactor of comparative example 1, and the results of the analysis are shown in fig. 1 and 2. As shown in fig. 1, (a) of fig. 1 shows a front microscope photograph of the microfluidic channel of the present invention, and (b) of fig. 1 is a schematic view of an interface obtained by cutting a single microfluidic channel in a longitudinal direction, in which it can be seen that a plurality of more minute transverse channels are contained. Fig. 2 is a cross-section taken along the axial direction of each of the angular microchannels (i.e., the up-down direction of fig. 1 (a)), and the angular channel shape thereof can be seen, while some aggregated solid matter, presumably agglomerated particles of the catalyst, can be seen. Fig. 2 shows that there is some agglomeration of solid particles in the diverging portion of the pipe section. The circled portion indicates where a blockage is likely, such that the passage of the liquid phase reactant can only be passed along one side in the direction of the arrow, thereby affecting the patency of the microfluidic channel. The inventors do not wish to be bound by any theory. However, the inventors believe that the weak basic environment may act to activate the movement of the particulate catalyst ions and prevent agglomeration of the particles. The experimental parameters in example 1 are preferred parameters, and a better yield of the final product, 4' -diaminodiphenyl ether, is obtained (the yield in the whole reaction time can reach more than 99%).

It can also be seen that in the examples consistent with embodiments of the present invention, even palladium on carbon catalyst ratios as high as 15% did not result in significant pipe plugging. In the comparative example, when the catalyst is added in a proportion of about 10%, there is a disadvantage that the pressure in the pipe increases after the reaction for a long time and the particles are clogged.

Experiment 2: alkaline solution concentration and addition test

The same parameters as in example 1 were used, except that the amount and ratio of the alkali added were varied. The effect of the base addition on the reaction system was tested. The main results are shown in Table 2.

Table 2: experiment 2-test conditions for different alkali concentrations

In the present invention, "yield" is defined as the ratio of the mass of the product (4, 4' -diaminodiphenyl ether) obtained in the actual production to the mass of the product which should theoretically be obtained using the corresponding mass of 4,4' -dinitrodiphenyl ether starting material employed (since hydrogen is in excess, the solvent and the catalyst are sufficient, and the theoretical yield of 4,4' -dinitrodiphenyl ether starting material is employed).

From the above reaction experiments, it can be seen that sodium bicarbonate solutions within the scope of the examples do not lead to a significant yield reduction. When the proportion of the sodium bicarbonate solution is increased to more than 10%, although the reaction process is still smooth, the yield of the product is obviously reduced. It is to be noted that when sodium hydroxide is used as the basic substance, the decrease in yield is remarkable even when a lower ratio of the sodium hydroxide solution and the solution concentration is used. This indicates that NaOH is not an ideal basic starting material. The inventors hypothesize that this may be related to the effect of the very strong basic species on the palladium on charcoal catalyst. From the series of experimental schemes, when the ratio of the sodium bicarbonate solution (wt%)/the concentration of the sodium bicarbonate solution (wt%) is 0.5 wt% and 2 wt%, respectively, a comprehensive excellent effect is obtained, so that the smoothness of the microchannel reactor in the reaction process is ensured, the good yield of the product is also ensured, and the waste and excessive consumption of raw materials and energy sources are avoided.

Experiment 3: improved microchannel reactor

Because the slurry improves the blocking effect, the structure and production parameters of the microchannel reactor can be further improved in order to further improve the reaction efficiency, so as to achieve the aim of further improving the production efficiency. In the preferred microchannel reactor structure, the channel in the microchannel reactor comprises a blocking structure, wherein the blocking structure is one or more protrusions arranged on the tube wall of the microchannel reactor (the protrusions can be arranged by methods such as microparticle flow deposition and the like as long as the microparticles do not react with subsequent reaction slurry, or a microchannel reactor device with a tube wall partition plate or a partition wall is adopted); the length-diameter ratio of the channel of the microchannel reactor is set to be 25000 to 40000; in the reaction process, the reaction linear speed of the fed slurry is 100-3000 m/min; the pressure in the channel gradually decreases as the slurry advances in the channel, the pressure between the inlet and the outlet being set between 4 and 6 bar.

The inventors further utilized the experiments of examples 1, 2, 3 and comparative example 1 shown in experiment 1 to apply to the microchannel reactor with a barrier structure of experiment 3. It was found in the experiment that when the parameters of comparative example 1 were applied, the microchannel reactor exhibited flow failure earlier. In the case of the embodiments 1 and 2, the arrangement of the blocking device and the arrangement of the large pressure difference do not hinder the smoothness of the microchannel reactor, and the reaction efficiency/speed can be improved by 5-10%. Experiment 3 further verifies the technological feasibility of the technical scheme of the invention and the adaptability of wider equipment devices.

According to the embodiments and technical contents described in the present specification, the present invention can provide at least the following technical means: while the present disclosure includes specific embodiments, it will be apparent to those skilled in the art that various substitutions or alterations in form and detail may be made to these embodiments without departing from the spirit and scope of the invention as defined by the appended claims and their equivalents. The embodiments described herein are to be considered in all respects only as illustrative and not restrictive. The description of features and aspects in each embodiment is believed to be applicable to similar features and aspects in other embodiments. Therefore, the scope of the present disclosure should be defined not by the detailed description but by the claims, and all changes within the scope of the claims and equivalents thereof should be construed as being included in the technical solution of the present disclosure.

According to the invention concept of the inventor, the invention can at least provide the following technical scheme:

1. a method for preparing diphenyl ether derivative by improved microchannel process comprises preparing slurry from raw diphenyl ether, Pd/C catalyst and solvent in certain proportion, and continuously feeding the slurry into microchannel reactor via slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; it is characterized in that the preparation method is characterized in that,

in the slurry thus prepared, a diluted alkaline substance is further mixed in an amount of about 0.1 to 2.0 wt% based on the total weight of the entire slurry.

2. The method of scheme 1, wherein the dilute alkaline material comprises sodium bicarbonate.

3. The process according to scheme 2, wherein the diluted alkaline substance is a sodium bicarbonate solution with a mass fraction of 1 to 10 wt%, preferably 1 to 5 wt%, most preferably 1 to 2 wt%.

4. The process according to any of schemes 1 through 3, wherein the diphenyl ether starting material comprises or is 4,4 '-dinitrodiphenyl ether and the diphenyl ether derivative comprises or is 4,4' -diaminodiphenyl ether.

5. The method according to any of embodiments 1-3, wherein the palladium on carbon catalyst mass is about 0.05% to about 25%, preferably 10 to 20%, 12% to 18%, most preferably 15% to 18% of the diphenyl ether starting material.

6. The method according to any of the schemes 1 to 3, wherein the method specifically comprises the steps of:

preparing 4,4' -dinitrodiphenyl ether, a palladium-carbon catalyst and a solvent into slurry, and mixing sodium bicarbonate solution which accounts for about 0.1-2 wt% of the total weight of the slurry and has the mass fraction of 1-2 wt% into the prepared slurry; after the mixture is uniformly mixed, continuously pumping the mixture into a micro-channel reactor by using a slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; reacting at the pressure of 0.3-1.8 MPa and the temperature of 50-200 ℃ until the palladium-carbon catalyst is separated from the microchannel reactor and enters a material receiving kettle, filtering to remove the palladium-carbon catalyst, removing the solvent in vacuum, performing primary recrystallization, separating out solids, performing secondary recrystallization, and separating and drying to obtain the product mainly comprising 4,4' -diaminodiphenyl ether.

7. The method of scheme 6, wherein optionally after filtering to remove the palladium on carbon catalyst and before vacuum removal of the solvent, comprising a step of washing the product with deionized water.

8. The method according to any one of aspects 1 to 7, wherein the mass proportion of the noble metal in the palladium-on-carbon catalyst is 1 to 10%, preferably 3 to 5%.

9. The process according to any one of schemes 1 to 8, wherein the molar ratio of the 4,4' -dinitrodiphenyl ether to hydrogen is 1:6.01 to 1: 6.6.

10. The process of any of schemes 1 through 9, wherein the microchannel reactor is a continuous flow microchannel reactor device;

the micro-channel continuous flow reactor is formed by connecting 1-20 micro-channel reactor modules;

the depth of the inner channel of the micro-channel reactor is 100 mu m-10 mm.

The liquid holdup of the microchannel reactor is 5-2500 mL;

and, optionally,

the module structure of the microchannel reactor is one of a micro-tubular structure, a groove-shaped structure, a T-shaped structure, a spherical baffle structure, a water drop-shaped structure, an umbrella-shaped structure or a heart-shaped structure;

the microchannel reactor is made of one of special glass, silicon carbide, sapphire, corrosion-resistant alloy and fluoropolymer.

11. The process according to any of the preceding embodiments, wherein the proportion of noble metal in the palladium on carbon catalyst is between 1 and 10%, preferably between 3 and 5%.

12. The method according to any one of the preceding claims, wherein the mass ratio of the 4,4' -dinitrodiphenyl ether to the solvent is 1: 1.5-1: 20.

13. The method according to any one of the preceding claims, wherein the solvent is one or more of an amide solvent, an aromatic solvent and an alcohol solvent.

14. The method according to any one of the preceding claims, wherein the molar ratio of the 4,4' -dinitrodiphenyl ether to the hydrogen gas is 1:5 to 1: 7.

15. The method according to any of the preceding claims, wherein the post-treatment comprises filtration, distillation, recrystallization and the like.

16. The method according to any of the preceding claims, wherein the solvent used for recrystallization comprises an aromatic hydrocarbon solvent, an alcohol solvent and water.

17. The method of any of the preceding aspects, wherein:

the channel in the microchannel reactor comprises a blocking structure, wherein the blocking structure is one or more protrusions arranged on the tube wall of the microchannel reactor; the length-diameter ratio of the channel of the microchannel reactor is more than 10000; preferably the aspect ratio of the channels is between 25000 and 40000; in the reaction process, the reaction linear speed of the slurry is 100-3000 m/min; and

the pressure in the passageway decreases progressively as the slurry advances in the passageway, the pressure difference between the inlet and outlet being between 2 and 6bar, preferably between 4 and 6 bar.

18. The method according to any of the preceding claims, wherein the parameters of the present invention may further be selected from one or more of the following:

the catalyst can be metal catalyst, lanthanum niobium nickel catalyst, palladium carbon catalyst, platinum carbon catalyst and ruthenium carbon catalyst; and/or

The alkaline substance is selected from one or more of organic base, triethylamine, trimethylamine, aniline, tert-butylamine, pyridine and piperidine alternatively or mixedly.

Claims (10)

1. A method for preparing diphenyl ether derivative by improved microchannel process comprises preparing raw diphenyl ether, palladium-carbon catalyst and solvent into slurry according to a certain proportion, and continuously inputting the slurry into microchannel reactor by slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; it is characterized in that the preparation method is characterized in that,

in the slurry thus prepared, a diluted alkaline substance is further mixed in an amount of about 0.1 to 2.0 wt% based on the total weight of the entire slurry.

2. The method of claim 1, wherein the dilute alkaline substance comprises a weakly alkaline substance, such as comprising sodium bicarbonate.

3. The process according to claim 2, wherein the diluted alkaline substance is a sodium bicarbonate solution with a mass fraction of 1 to 10 wt%, preferably 1 to 5 wt%, most preferably 1 to 2 wt%.

4. A process according to any one of claims 1 to 3 wherein the diphenyl ether starting material comprises or is 4,4 '-dinitrodiphenyl ether and the diphenyl ether derivative comprises or is 4,4' -diaminodiphenyl ether.

5. The method according to any one of claims 1 to 3, wherein the palladium on carbon catalyst mass is from about 0.05% to about 25%, preferably 10 to 20%, 12% to 18%, most preferably 15% to 18% of the diphenyl ether starting material.

6. The method according to any one of claims 1 to 3, wherein the method comprises in particular the steps of:

preparing 4,4' -dinitrodiphenyl ether, a palladium-carbon catalyst and a solvent into slurry, and mixing sodium bicarbonate solution which accounts for about 0.1-2 wt% of the total weight of the slurry and has the mass fraction of 1-2 wt% into the prepared slurry; after the mixture is uniformly mixed, continuously pumping the mixture into a micro-channel reactor by using a slurry pump; simultaneously, introducing hydrogen into the microchannel reactor through a hydrogen feeding part; reacting at the pressure of 0.3-1.8 MPa and the temperature of 50-200 ℃ until the palladium-carbon catalyst is separated from the microchannel reactor and enters a material receiving kettle, filtering to remove the palladium-carbon catalyst, removing the solvent in vacuum, performing primary recrystallization, separating out solids, performing secondary recrystallization, and separating and drying to obtain the product mainly comprising 4,4' -diaminodiphenyl ether.

7. The method of claim 6, optionally comprising a step of washing the product with deionized water after filtering to remove the palladium on carbon catalyst and before removing the solvent in vacuo.

8. The process according to any one of claims 1 to 7, wherein the mass percentage of noble metal in the palladium on carbon catalyst is 1-10%, preferably 3-5%; and/or

Wherein the molar ratio of the 4,4' -dinitrodiphenyl ether to the hydrogen is 1: 6.01-1: 6.6.

9. The process of any one of claims 1 to 8, wherein the microchannel reactor is a microchannel continuous flow reactor;

the micro-channel continuous flow reactor is formed by connecting 1-20 micro-channel reactor modules;

the depth of the inner channel of the micro-channel continuous flow reactor is 100 mu m-10 mm,

the liquid holdup of the micro-channel continuous flow reactor is 5-2500 mL;

and, optionally,

the module structure of the micro-channel continuous flow reactor is one of a micro-tubular structure, a groove-shaped structure, a T-shaped structure, a spherical structure, a water drop-shaped structure, an umbrella-shaped structure or a heart-shaped structure;

the material of the micro-channel continuous flow reactor is one of special glass, silicon carbide, sapphire, corrosion-resistant alloy and fluoropolymer.

10. The method of any one of claims 1 to 9, wherein

The channel in the microchannel reactor comprises a blocking structure, wherein the blocking structure is one or more protrusions arranged on the tube wall of the microchannel reactor; the length-diameter ratio of the channel of the microchannel reactor is more than 10000; preferably the aspect ratio of the channels is between 25000 and 40000; in the reaction process, the reaction linear speed of the slurry is 100-3000 m/min; and

the pressure in the channel gradually decreases as the slurry advances in the channel, and the pressure difference between the inlet and the outlet of the microchannel continuous flow reactor is 2bar to 6bar, preferably 4bar to 6 bar.

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