Method for continuously preparing aromatic aldehyde
By reacting the replacement benzene with the oxidant in the microchannel reaction device, the problems of long reaction time and poor selectivity in the traditional aromatic aldehyde production process are solved, and efficient and safe aromatic aldehyde synthesis is achieved, with high product yield and shorter production cycles. .
Patent Information
- Application Number
- CN202310781055.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-28
- Publication Date
- 2024-12-31
AI Technical Summary
Traditional aromatic aldehyde production processes have problems such as long reaction time, poor selectivity, high energy consumption, environmental pollution and unsafe production. Especially due to the design of the reactor, the heat release is not timely, the temperature control is not accurate, the stirring is not uniform, and the side reactions are not uniform. frequently.
The aromatic aldehyde is continuously prepared by using a microchannel reaction device. By reacting the substituted benzene with the oxidant in an organic solvent in the micro reactor, the heat transfer and mass transfer process are accelerated by the miniaturized structure of the microchannel to achieve efficient aromatic aldehyde synthesis.
It has achieved short reaction time, high product conversion rate, high safety, reduced side reactions, shortened production cycle, and the yield of aromatic aldehydes can reach 97.5%, overcoming the shortcomings of traditional processes and having the characteristics of high efficiency and safety.
Smart Images
Figure CN119219478A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of chemical synthesis and process technology, and in particular to a method for continuously preparing aromatic aldehydes. Background Art
[0002] Aromatic aldehydes are important chemical raw materials. In the synthesis of medicines, pesticides, new materials, etc., aromatic aldehydes play an important role as reaction intermediates. Due to their good thermal stability and high fat solubility, the application field of aromatic aldehydes has been continuously expanded in recent years, and the market demand has increased greatly. For example, p-fluorobenzaldehyde can be used to synthesize phenylnaphthylpyran, a drug for treating immune system diseases and diabetic complications, fluphenazine, a drug for treating nervous system diseases, and rosuvastatin, a lipid-lowering drug. Aromatic aldehydes are often used as raw materials to synthesize many important chemicals. For example, p-fluorobenzaldehyde, yeast and glucose can react to produce (1R, 2S)-1-naphthyl-1,2-propanediol; solid substrates are aluminum oxide, and p-fluorobenzaldehyde reacts with fluorene in the presence of potassium fluoride to prepare phenylene organic compounds. In addition, aromatic aldehydes can also be used as cosmetic additives, plant protection agents and fungicides, etc., and have a wide range of uses. Therefore, the development of aromatic aldehydes has good economic and social benefits.
[0003] The production of aromatic aldehydes is mainly concentrated in Japan and the United States. The domestic production capacity of aromatic aldehydes is very small, the technology is backward, and most of it depends on imports. With the continuous expansion of its application fields, the demand at home and abroad has increased sharply, and the development prospects of the product are broad. The development and research of aromatic aldehydes is of great significance.
[0004] Aromatic aldehydes are produced in large reactors in industrial production, which have the disadvantages of not being able to release the heat released by the reaction in time, not being able to accurately control the reaction temperature, uneven stirring of the reaction liquid, large amounts of "three wastes", and high costs. These disadvantages can easily lead to side reactions, complex process operations, and unsafe production. The traditional chemical method for preparing aromatic aldehydes has the disadvantages of long reaction time, poor reaction selectivity (there are a lot of over-reduction products, aromatic alcohols), and high consumption of reducing agents. Summary of the invention
[0005] The purpose of the present invention is to provide a method for continuously preparing aromatic aldehydes, so as to overcome the defects of a traditional reactor and the problems of long production cycle, large amount of trifluoroacetic acid, high energy consumption, environmental pollution, unsafe production, etc. in the prior art.
[0006] In order to achieve the above-mentioned object, the present invention provides a method for continuously preparing aromatic aldehydes, which comprises: reacting substituted benzene with an oxidant in a microchannel reaction device in the presence of an organic solvent, wherein the microchannel reaction device comprises a microreactor, and the microreactor comprises a microchannel and a plurality of spaced mixed structure units arranged in the microchannel.
[0007] Preferably, each of the mixing structure units comprises 2-6 fin structures arranged around the inner wall of the microchannel.
[0008] Preferably, the fin structure is a triangle, preferably an isosceles triangle, and more preferably an isosceles triangle with an acute vertex angle.
[0009] Preferably, the top angle of the fin structure is 5-85°, preferably 30-75°.
[0010] Preferably, the tip of the fin structure faces a direction opposite to the flow direction of the fluid in the microchannel.
[0011] Preferably, the angle between the fin structure and the inner wall of the microchannel is 5-75°, preferably 60-75°.
[0012] Preferably, the inner diameter of the microchannel is 0.2-2 mm.
[0013] Preferably, the holding volume in the microchannel is 0.2-6 mL.
[0014] Preferably, the height of the fin structure is 0.02-1 mm, preferably 0.3-0.8 mm.
[0015] Preferably, the distance between two adjacent hybrid structure units is 1-5 cm.
[0016] Preferably, the microreactor is a coil structure.
[0017] Preferably, the microchannel reaction device further comprises a micro mixer and a receiver, the reaction materials are first mixed in the micro mixer and then enter the microreactor for reaction, and the mixture obtained after the reaction enters the receiver.
[0018] Preferably, the length of the connecting pipe between the micromixer and the microreactor is 10-50 cm, and the length of the connecting pipe between the microreactor and the receiver is 10-50 cm.
[0019] Preferably, the substituted benzene and the oxidant are fed in the following manner: dissolving the substituted benzene in the organic solvent to obtain a substituted benzene solution, dissolving the oxidant in the organic solvent to obtain an oxidant solution, and then injecting the substituted benzene solution and the oxidant solution into the micromixer respectively.
[0020] Preferably, the molar ratio of the substituted benzene to the oxidant is 1:1-3.
[0021] Preferably, the substituted benzene is as shown in formula (I),
[0022]
[0023] Wherein, R is a C1-C10 alkyl group, a C6-C15 aryl group, an acyl group, an ether group or a halogen group.
[0024] Preferably, the oxidant is one or any combination of two or more of hexamethylenetetramine, potassium permanganate, potassium dichromate, chromium trioxide and ruthenium tetroxide.
[0025] Preferably, the organic solvent is one of trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, acetic acid and propionic acid, or any combination of two or more thereof.
[0026] Preferably, the flow rate of the continuous flow entering the microreactor is 0.05-0.2 mL / min, preferably 0.8-1.2 mL / min.
[0027] Preferably, the reaction conditions in the microreactor include: a temperature of 60-120° C., preferably 95-105° C.; and a reaction time of 5-30 min, preferably 10-20 min.
[0028] In the method for continuously preparing aromatic aldehydes described in the present invention, the reaction process of substituted benzene and oxidant is carried out in the microchannel of the microreactor. The diffusion distance between molecules in the microchannel is short, the specific surface area of the microchannel is large, and the miniaturization of the size strengthens the heat transfer and mass transfer process of the equipment. Therefore, the method described in the present invention uses a microreactor to replace the traditional reactor to produce aromatic aldehydes, which can overcome the shortcomings of the traditional production process and is of great significance.
[0029] Compared with the prior art, the technical solution of the present invention has the following advantages:
[0030] (1) The present invention adopts a microreactor to synthesize aromatic aldehydes, which has a short reaction time (generally less than 30 minutes), a high product conversion rate, is easy to operate, and is highly safe. It can overcome the shortcomings of traditional reaction kettles (bottles) and is both efficient and safe.
[0031] (2) The present invention can achieve continuous production through precise control of the reaction, with a short production cycle, thus avoiding the generation of a large number of side reactions;
[0032] (3) The yield of the target aromatic aldehyde product in the present invention can be as high as 97.5%. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 It is a structural schematic diagram of a microchannel reaction device used in the method for continuously preparing aromatic aldehydes according to the present invention;
[0034] Figure 2 Schematic diagram of the internal structure of a microreactor in a microchannel reaction device, wherein the direction of the arrow indicates the fluid flow direction of the reaction material;
[0035] Figure 3 is a radial cross-sectional view of the microreactor.
[0036] Description of Reference Numerals
[0037] 1. Microreactor; 2. Micromixer; 3. Receiver; 4. First injector; 5. Second injector; 6. Fin structure. DETAILED DESCRIPTION
[0038] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.
[0039] The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.
[0040] The method for continuously preparing aromatic aldehydes of the present invention comprises: reacting substituted benzene with an oxidant in a microchannel reaction device in the presence of an organic solvent.
[0041] In the present invention, if Figure 1 As shown, the microchannel reaction device comprises a microreactor 1, and the microreactor 1 comprises a microchannel and a plurality of mixing structure units arranged at intervals in the microchannel.
[0042] In a preferred embodiment, in the microreactor 1, Figure 2 and 3 As shown, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel. Specifically, the number of fin structures 6 may be 2, 3, 4, 5 or 6, for example.
[0043] In a preferred embodiment, in order to obtain a higher yield of the target product, the fin structure 6 is a triangle, more preferably an isosceles triangle, and further preferably an isosceles triangle with an acute vertex angle. Figure 3 As shown), the top angle of the fin structure 6 can be 5-85°, preferably 30-75°, specifically, for example, 30°, 40°, 45°, 50°, 60°, 65°, 70° or 75°.
[0044] In a preferred embodiment, in order to obtain a higher yield of the target product, the tip of the fin structure 6 is oriented in the opposite direction to the flow direction of the fluid in the microchannel (eg Figure 2 Further preferably, the angle between the fin structure and the inner wall of the microchannel (also referred to as "fin inclination angle") is 5-75°, more preferably 60-75°, and specifically, for example, 60°, 65°, 70° or 75°.
[0045] In the microreactor 1, the inner diameter of the microchannel can be 0.2-2mm, preferably 0.5-2mm, specifically, for example, can be 0.5mm, 0.8mm, 1mm, 1.2mm, 1.5mm, 1.8mm or 2mm. Most preferably, the inner diameter of the microchannel is 1mm. In this article, the inner diameter of the microchannel refers to the radius of the microchannel lumen.
[0046] In the microreactor 1, the holding volume in the microchannel may be 0.2-6 mL, preferably 1-6 mL, and more preferably 2-4 mL.
[0047] In the microreactor 1, the height of the fin structure 6 can be 0.02-1mm, preferably 0.3-0.8mm, specifically, for example, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm or 0.8mm. In this article, the height of the fin structure 6 refers to the vertical height from the apex angle of the fin (i.e. the apex of the tip) to the tube wall.
[0048] In the microreactor 1, the distance between two adjacent mixing structure units in the microchannel may be 1-5 cm, specifically, for example, 1 cm, 2 cm, 3 cm, 4 cm or 5 cm.
[0049] In a more preferred embodiment, in order to obtain a higher yield of the target product, the microreactor is a coil structure.
[0050] In the present invention, if Figure 1As shown, the microchannel reaction device may also include a micromixer 2 and a receiver 3. The reaction materials are first mixed in the micromixer 2 and then enter the microreactor 1 for reaction. The mixture obtained after the reaction enters the receiver 3. The length of the connecting pipe between the micromixer 2 and the microreactor 1 can be 10-50cm, and the length of the connecting pipe between the microreactor 1 and the receiver 3 can be 10-50cm. Further, the microchannel reaction device also includes a first injector 4 and a second injector 5. The substituted benzene is injected into the micromixer 2 in the form of a solution through the first injector 4, or directly injected into the microreactor 1; the oxidant is injected into the micromixer 2 in the form of a solution through the second injector 5, or directly injected into the microreactor 1.
[0051] In the present invention, the micro mixer 2 may be a conventional structure in the art. In some embodiments, the micro mixer 2 includes a micro channel and an enhanced mixing structure disposed in the micro channel, and the enhanced mixing structure may be, for example, a tee.
[0052] In the present invention, the material of the microreactor 1 is preferably a corrosion-resistant material, such as a titanium-based material or a silicon carbide material.
[0053] In the present invention, the connecting pipe between the micro-mixer 2 and the micro-reactor 1 and the connecting pipe between the micro-reactor 1 and the receiver 3 are preferably made of corrosion-resistant materials, such as polytetrafluoroethylene.
[0054] According to some embodiments of the present invention, the microchannel reaction device includes a microreactor 1 and a receiver 3, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction material enters the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of spaced mixing structure units arranged in the microchannel, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the fin structure 6 is triangular, and the spacing between two adjacent mixing structure units in the microchannel is 1-5 cm.
[0055] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1 and a receiver 3, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction material enters the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of spaced mixed structure units arranged in the microchannel, each of the mixed structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the fin structure 6 is an isosceles triangle, the inner diameter of the microchannel is 0.2-2mm, the holding volume in the microchannel is 0.2-6mL, the spacing between two adjacent mixed structure units in the microchannel is 1-5cm, and the height of the fin structure 6 is 0.02-1mm.
[0056] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1 and a receiver 3, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction material enters the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of spaced mixing structure units arranged in the microchannel, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the fluid flow in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, and the height of the fin structure 6 is 0.3-0.8mm.
[0057] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1 and a receiver 3, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction material enters the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of spaced mixing structure units arranged in the microchannel, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the fluid flow direction in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, and the vertex angle of the fin structure 6 is 5-85°, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, the height of the fin structure 6 is 0.3-0.8mm, and the angle between the fin structure and the inner wall of the microchannel is 5-75°.
[0058] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1 and a receiver 3, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction material enters the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of spaced mixing structure units arranged in the microchannel, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the fluid flow direction in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, and the vertex angle of the fin structure 6 is 30-75°, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, the height of the fin structure 6 is 0.3-0.8mm, the angle between the fin structure and the inner wall of the microchannel is 60-75°, and the microreactor is a coil structure.
[0059] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1, a micromixer 2 and a receiver 3, the micromixer 2 and the microreactor 1 are connected by a connecting pipe, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction materials are first mixed in the micromixer 2 and then enter the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of mixing structure units arranged at intervals in the microchannel, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the flow direction of the fluid in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, and the height of the fin structure 6 is 0.3-0.8mm.
[0060] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1, a micromixer 2 and a receiver 3, the micromixer 2 and the microreactor 1 are connected by a connecting pipe, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the reaction materials are first mixed in the micromixer 2 and then enter the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of mixing structure units arranged at intervals in the microchannel, each of the mixing structure units includes a microchannel surrounding the microchannel 2-6 fin structures 6 are arranged on the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the flow direction of the fluid in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, and the vertex angle of the fin structure 6 is 5-85°, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, the height of the fin structure 6 is 0.3-0.8mm, and the angle between the fin structure and the inner wall of the microchannel is 5-75°.
[0061] According to some other embodiments of the present invention, the microchannel reaction device includes a microreactor 1, a micromixer 2, a receiver 3, a first injector 4 and a second injector 5, the micromixer 2 and the microreactor 1 are connected by a connecting pipe, the microreactor 1 and the receiver 3 are connected by a connecting pipe, the substituted benzene is injected into the micromixer 2 in the form of a solution through the first injector 4, the oxidant is injected into the micromixer 2 in the form of a solution through the second injector 5, then the materials are mixed in the micromixer 2, and then enter the microreactor 1 for reaction, and the mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a A plurality of spaced-apart mixing structure units, each of the mixing structure units includes 2-6 fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the flow direction of the fluid in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, and the vertex angle of the fin structure 6 is 30-75°, the inner diameter of the microchannel is 0.5-2mm, the holding volume in the microchannel is 1-6mL, the spacing between two adjacent mixing structure units in the microchannel is 1-5cm, the height of the fin structure 6 is 0.3-0.8mm, the angle between the fin structure and the inner wall of the microchannel is 60-75°, and the microreactor is a coil structure.
[0062] In the method for continuously preparing aromatic aldehydes described in the present invention, preferably, the substituted benzene and the oxidant are fed in the following manner: the substituted benzene is dissolved in the organic solvent to obtain a substituted benzene solution, the oxidant is dissolved in the organic solvent to obtain an oxidant solution, and then the substituted benzene solution and the oxidant solution are respectively injected into the micromixer 2 or the microreactor 1.
[0063] In the method for continuously preparing aromatic aldehydes described in the present invention, the molar ratio of the substituted benzene to the oxidant can be 1:1-3, preferably 1:1-2, and specifically, for example, can be 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9 or 1:2.
[0064] In the method for continuously preparing aromatic aldehydes of the present invention, the substituted benzene is as shown in formula (I),
[0065]
[0066] Wherein, R is a C1-C10 alkyl group, a C6-C15 aryl group, an acyl group, an ether group or a halogen group.
[0067] In the present invention, the structural formula of the acyl group is -CO-R1, wherein R1 is a C1-C10 alkyl group or a C6-C15 aryl group.
[0068] In the present invention, the structural formula of the ether group is -R2-O-R3, wherein R2 is a C1-C10 alkylene group or a C6-C15 arylene group, and R3 is a C1-C10 alkyl group or a C6-C15 aryl group.
[0069] In the present invention, alkyl refers to a straight chain alkyl, a branched alkyl or a cycloalkyl. Specifically, examples of alkyl include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, tert-pentyl, neopentyl, n-hexyl, n-heptyl, n-octyl, n-decyl, cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, 4-ethylcyclohexyl, 4-n-propylcyclohexyl and 4-n-butylcyclohexyl.
[0070] In the present invention, examples of aryl include, but are not limited to, phenyl, 4-methylphenyl, 4-ethylphenyl, dimethylphenyl, and vinylphenyl.
[0071] In the present invention, halogen is fluorine, chlorine, bromine or iodine.
[0072] In the method for continuously preparing aromatic aldehydes described in the present invention, the oxidant can be selected from one or any combination of two or more of hexamethylenetetramine (also known as "urotropine"), potassium permanganate, potassium dichromate, chromium trioxide and ruthenium tetroxide, and hexamethylenetetramine is most preferred.
[0073] In the method for continuously preparing aromatic aldehydes of the present invention, the organic solvent can be selected from one or any combination of two or more of trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, acetic acid and propionic acid, and trifluoroacetic acid is most preferred.
[0074] In the method for continuously preparing aromatic aldehydes described in the present invention, the flow rate of the continuous flow entering the microreactor can be 0.05-0.2 mL / min, preferably 0.8-1.2 mL / min, specifically, for example, it can be 0.8 mL / min, 0.9 mL / min, 1 mL / min, 1.1 mL / min or 1.2 mL / min.
[0075] In the method for continuously preparing aromatic aldehydes of the present invention, the reaction conditions in the microreactor may include: a temperature of 60-120° C., preferably 95-105° C.; and a reaction time of 5-30 min, preferably 10-20 min.
[0076] According to some specific embodiments of the method for continuously preparing aromatic aldehydes according to the present invention, the method comprises: in the presence of an organic solvent, reacting substituted benzene with an oxidant in a microreactor 1 of a microchannel reaction device, wherein the molar ratio of the substituted benzene to the oxidant is 1:1-3, the flow rate of the continuous flow entering the microreactor is 0.05-0.2 mL / min, and the reaction conditions in the microreactor include: a temperature of 60-120°C and a reaction time of 5-30 min.
[0077] According to other specific embodiments of the method for continuously preparing aromatic aldehydes according to the present invention, the method comprises: in the presence of an organic solvent, reacting substituted benzene with an oxidant in a microreactor 1 of a microchannel reaction device, wherein the molar ratio of the substituted benzene to the oxidant is 1:1-2, the flow rate of the continuous flow entering the microreactor is 0.8-1.2 mL / min, and the reaction conditions in the microreactor include: a temperature of 95-105°C and a reaction time of 10-20 min.
[0078] According to other specific embodiments of the method for continuously preparing aromatic aldehydes according to the present invention, the method comprises: the substituted benzene is injected into the micromixer 2 in the form of a solution through the first injector 4, the oxidant is injected into the micromixer 2 in the form of a solution through the second injector 5, then the materials are mixed in the micromixer 2, and then enter the microreactor 1 for reaction, wherein the molar ratio of the substituted benzene to the oxidant is 1:1-2, the flow rate of the continuous flow entering the microreactor is 0.8-1.2mL / min, and the reaction conditions in the microreactor include: temperature of 95-105°C, reaction time of 10-20min.
[0079] According to some other specific embodiments of the method for continuously preparing aromatic aldehydes according to the present invention, the method comprises: the substituted benzene is injected into the micro mixer 2 in the form of a solution through the first injector 4, the oxidant is injected into the micro mixer 2 in the form of a solution through the second injector 5, and then the materials are mixed in the micro mixer 2 and then enter the microreactor 1 for reaction, wherein the substituted benzene is as shown in formula (I),
[0080]
[0081] Wherein, R is C1-C10 alkyl, C6-C15 aryl, acyl, ether or halogen;
[0082] The oxidant is selected from one or any combination of two or more of hexamethylenetetramine, potassium permanganate, potassium dichromate, chromium trioxide and ruthenium tetroxide;
[0083] The organic solvent used in the solution of substituted benzene and the solution of oxidant is selected from one or any combination of two or more of trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, acetic acid and propionic acid;
[0084] The molar ratio of the substituted benzene to the oxidant is 1:1-2, the flow rate of the continuous flow entering the microreactor is 0.8-1.2 mL / min, and the reaction conditions in the microreactor include: temperature of 95-105° C., and reaction time of 10-20 min.
[0085] According to some other specific embodiments of the method for continuously preparing aromatic aldehydes according to the present invention, the method comprises: the substituted benzene is injected into the micro mixer 2 in the form of a solution through the first injector 4, the oxidant is injected into the micro mixer 2 in the form of a solution through the second injector 5, and then the materials are mixed in the micro mixer 2 and then enter the microreactor 1 for reaction, wherein the substituted benzene is as shown in formula (I),
[0086] Wherein, R is C1-C6 alkyl (especially methyl);
[0087] The oxidant is hexamethylenetetramine, and the organic solvent used in the solution of substituted benzene and the solution of the oxidant is trifluoroacetic acid; the molar ratio of the substituted benzene to the oxidant is 1:1-2, the flow rate of the continuous flow entering the microreactor is 0.8-1.2 mL / min, and the reaction conditions in the microreactor include: temperature of 95-105° C. and reaction time of 10-20 min.
[0088] In the method for continuously preparing aromatic aldehydes described in the present invention, in order to obtain the target product aromatic aldehyde, the method also includes collecting the reaction mixture with a receiver 3 (such as a beaker), adding ice water to quench, then adjusting the pH value to 7-8 with an alkali solution (such as a saturated sodium carbonate aqueous solution), and then extracting with ethyl acetate and concentrating to obtain the product.
[0089] The method for continuously preparing aromatic aldehydes of the present invention is further illustrated by examples. The examples are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the present invention is not limited to the following examples.
[0090] The experimental methods in the following examples, unless otherwise specified, are all conventional methods in the art. The experimental materials used in the following examples, unless otherwise specified, are all commercially available.
[0091] The microchannel reaction device used in the following embodiments includes a microreactor 1, a micromixer 2, a receiver 3, a first injector 4 and a second injector 5. The micromixer 2 is connected to the microreactor 1 by a connecting pipe, and the microreactor 1 is connected to the receiver 3 by a connecting pipe. The substituted benzene is injected into the micromixer 2 in the form of a solution through the first injector 4, and the oxidant is injected into the micromixer 2 in the form of a solution through the second injector 5. Then the materials are mixed in the micromixer 2 and then enter the microreactor 1 for reaction. The mixture obtained after the reaction enters the receiver 3, wherein the microreactor 1 includes a microchannel and a plurality of mixing structure units arranged at intervals in the microchannel, each of the mixing structure units includes a plurality of fin structures 6 arranged around the inner wall of the microchannel, the tip of the fin structure 6 faces the direction opposite to the flow direction of the fluid in the microchannel, the fin structure 6 is an isosceles triangle with an acute vertex angle, and the microreactor is a coil structure. The relevant structural parameters of the fin structure and the microchannel are specifically given in each embodiment.
[0092] Example 1
[0093] Take toluene (25.00ml, 0.145mol) and dissolve it in trifluoroacetic acid (125mL), and load it in the first raw material storage tank after it is completely dissolved; take urotropine (20.40g, 0.145mol) and dissolve it in trifluoroacetic acid (125mL), and load it in the second raw material storage tank after it is completely dissolved. The feed liquid in the first raw material storage tank and the second raw material storage tank is pumped into the microchannel reaction device through the first injector 4 and the second injector 5 respectively. Specifically, the feed liquid enters the microreactor 1 for reaction after mixing by the micro mixer 2. The inner diameter of the coil of the microreactor 1 is 1mm, and the holding volume is 2mL. The structural parameters of the mixed structure unit in the microchannel of the microreactor 1 are: the height of the fin structure is 0.7mm, the top angle of the fin structure is 60°, the number of fins is 4, the inclination angle of the fin is 60°, and the spacing between two adjacent mixed structure units is 2cm; set the microreactor parameters: the flow rate of the continuous flow is 0.1mL / min, the reaction temperature is 100°C, and the reaction time is 10min. The reaction mixture was collected in a beaker and quenched by adding an appropriate amount of ice water. The pH value of the reaction mixture was then adjusted to 7-8 with a saturated aqueous sodium carbonate solution. The mixture was then extracted with an appropriate amount of ethyl acetate and concentrated to obtain the product p-methylbenzaldehyde in a yield of 97.5%.
[0094] Example 2
[0095] p-Tolualdehyde was prepared according to the method of Example 1, except that the height of the fin structure was 0.3 mm in the structural parameters of the mixing structure unit in the microchannel of the microreactor 1. As a result, the yield of the product p-Tolualdehyde was 83.1%.
[0096] Example 3
[0097] p-Tolualdehyde was prepared according to the method of Example 1, except that the height of the fin structure was 0.8 mm in the structural parameters of the mixing structure unit in the microchannel of the microreactor 1. As a result, the yield of the product p-Tolualdehyde was 97.7%.
[0098] Example 4
[0099] p-Tolualdehyde was prepared according to the method of Example 1, except that the top angle of the fin structure in the structural parameters of the mixing structure unit in the microchannel of the microreactor 1 was 30°. As a result, the yield of the product p-Tolualdehyde was 87.4%.
[0100] Example 5
[0101] p-Tolualdehyde was prepared according to the method of Example 1, except that the number of fins in the structural parameters of the mixing structural unit in the microchannel of the microreactor 1 was 3. As a result, the yield of the product p-Tolualdehyde was 86.1%.
[0102] Example 6
[0103] p-Tolualdehyde was prepared according to the method of Example 1, except that the fin inclination angle was 30° in the structural parameters of the mixing structural unit in the microchannel of the microreactor 1. As a result, the yield of the product p-Tolualdehyde was 79.9%.
[0104] Example 7
[0105] p-Tolualdehyde was prepared according to the method of Example 1, except that the distance between two adjacent mixing structural units in the microchannel of the microreactor 1 was 1 cm. As a result, the yield of the product p-Tolualdehyde was 98.1%.
[0106] Example 8
[0107] p-Tolualdehyde was prepared according to the method of Example 1, except that the distance between two adjacent mixing structure units in the microchannel of the microreactor 1 was 5 cm. As a result, the yield of the product p-Tolualdehyde was 91.3%.
[0108] Example 9
[0109] p-Tolualdehyde was prepared according to the method of Example 1, except that the number of fins in the structural parameters of the mixing structural unit in the microchannel of the microreactor 1 was 2. As a result, the yield of the product p-Tolualdehyde was 86.7%.
[0110] Example 10
[0111] p-Tolualdehyde was prepared according to the method of Example 1, except that in the structural parameters of the mixing structural unit in the microchannel of the microreactor 1, the number of fins was 2 and the fin inclination angle was 75°. As a result, the yield of the product p-Tolualdehyde was 95.7%.
[0112] Embodiment 11
[0113] p-Tolualdehyde was prepared according to the method of Example 1, except that the top angle of the fin structure in the structural parameters of the mixing structure unit in the microchannel of the microreactor 1 was 75°. As a result, the yield of the product p-Tolualdehyde was 93.3%.
[0114] Example 12
[0115] p-Tolualdehyde was prepared according to the method of Example 1, except that the reaction temperature was 80° C. As a result, the yield of the product p-Tolualdehyde was 82.0%.
[0116] Embodiment 13
[0117] p-Tolualdehyde was prepared according to the method of Example 1, except that the reaction temperature was 120° C. As a result, the yield of the product p-Tolualdehyde was 93.8%.
[0118] Embodiment 14
[0119] The p-methylbenzaldehyde was prepared according to the method of Example 1, except that the reaction time was 5 min. As a result, the yield of the product p-methylbenzaldehyde was 90.2%.
[0120] Embodiment 15
[0121] The p-methylbenzaldehyde was prepared according to the method of Example 1, except that the reaction time was 20 min. As a result, the yield of the product p-methylbenzaldehyde was 92.5%.
[0122] Example 16
[0123] The p-methylbenzaldehyde was prepared according to the method of Example 1, except that the reaction time was 30 min. As a result, the yield of the product p-methylbenzaldehyde was 94.9%.
[0124] Embodiment 17
[0125] p-Tolualdehyde was prepared according to the method of Example 1, except that the inner diameter of the coil was 0.2 mm and the height of the fin structure was 0.14 mm. As a result, the yield of the product p-Tolualdehyde was 93.9%.
[0126] Embodiment 18
[0127] p-Tolualdehyde was prepared according to the method of Example 1, except that the inner diameter of the coil was 0.5 mm and the height of the fin structure was 0.35 mm. As a result, the yield of the product p-Tolualdehyde was 96.9%.
[0128] Embodiment 19
[0129] p-Tolualdehyde was prepared according to the method of Example 1, except that the inner diameter of the coil was 2 mm and the height of the fin structure was 1.4 mm. As a result, the yield of the product p-Tolualdehyde was 84.9%.
[0130] Embodiment 20
[0131] p-Tolualdehyde was prepared according to the method of Example 1, except that the holding volume of the coil was 0.2 mL. As a result, the yield of the product p-Tolualdehyde was 84.9%.
[0132] Embodiment 21
[0133] p-Tolualdehyde was prepared according to the method of Example 1, except that the holding volume of the coil was 1 mL. As a result, the yield of the product p-Tolualdehyde was 90.9%.
[0134] Embodiment 22
[0135] p-Tolualdehyde was prepared according to the method of Example 1, except that the holding volume of the coil was 4 mL. As a result, the yield of the product p-Tolualdehyde was 91.9%.
[0136] Embodiment 23
[0137] p-Tolualdehyde was prepared according to the method of Example 1, except that the holding volume of the coil was 6 mL. As a result, the yield of the product p-Tolualdehyde was 95.9%.
[0138] Embodiment 24
[0139] p-Tolualdehyde was prepared according to the method of Example 1, except that the flow rate of the continuous flow was 0.05 mL / min. As a result, the yield of the product p-Tolualdehyde was 97.2%.
[0140] Embodiment 25
[0141] p-Tolualdehyde was prepared according to the method of Example 1, except that the flow rate of the continuous flow was 0.2 mL / min. As a result, the yield of the product p-Tolualdehyde was 89.9%.
[0142] Comparative Example 1
[0143] Toluene (25.00 ml, 0.145 mol), trifluoroacetic acid (250 ml) and urotropine (20.40 g, 0.145 mol) were added to a glass reaction bottle in sequence, the temperature was raised to 100°C and stirred for 12 h, the trifluoroacetic acid was evaporated under reduced pressure, and ice water (250 ml) was added. Under stirring, the pH value of the reaction mixture was adjusted to 7-8 with a saturated aqueous sodium carbonate solution, and then extracted with an appropriate amount of ethyl acetate and concentrated to obtain the product p-methylbenzaldehyde with a yield of 75.5%.
[0144] It can be seen from the results of the above examples that the aromatic aldehydes prepared according to the method of the present invention have a high product yield, can achieve continuous production, have a short production cycle (generally less than 30 minutes), are easy to operate, and are highly safe.
[0145] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.
Claims
1. A method for continuously preparing aromatic aldehydes, characterized in that: The method comprises: reacting substituted benzene with an oxidant in a microchannel reaction device in the presence of an organic solvent, wherein the microchannel reaction device comprises a microreactor, and the microreactor comprises a microchannel and a plurality of spaced mixed structural units arranged in the microchannel.
2. The method according to claim 1, characterized in that Each of the mixing structure units includes 2-6 fin structures arranged around the inner wall of the microchannel; Preferably, the fin structure is a triangle, preferably an isosceles triangle, and more preferably an isosceles triangle with an acute vertex angle; Preferably, the top angle of the fin structure is 5-85°, preferably 30-75°.
3. The method according to claim 2, characterized in that The tip of the fin structure faces a direction opposite to the flow direction of the fluid in the microchannel; Preferably, the angle between the fin structure and the inner wall of the microchannel is 5-75°, preferably 60-75°.
4. The method according to claim 2 or 3, characterized in that: The inner diameter of the microchannel is 0.2-2 mm; Preferably, the holding volume in the microchannel is 0.2-6 mL; Preferably, the height of the fin structure is 0.02-1 mm, preferably 0.3-0.8 mm; Preferably, the distance between two adjacent hybrid structure units is 1-5 cm.
5. The method according to any one of claims 1 to 4, characterized in that: The microreactor is a coil structure.
6. The method according to any one of claims 1 to 5, characterized in that: The microchannel reaction device also includes a micro mixer and a receiver. The reaction materials are first mixed in the micro mixer and then enter the micro reactor for reaction. The mixture obtained after the reaction enters the receiver.
7. The method according to claim 6, characterized in that The substituted benzene and the oxidant are fed in the following manner: the substituted benzene is dissolved in the organic solvent to obtain a substituted benzene solution, the oxidant is dissolved in the organic solvent to obtain an oxidant solution, and then the substituted benzene solution and the oxidant solution are respectively injected into the micromixer.
8. The method according to any one of claims 1 to 7, characterized in that: The molar ratio of the substituted benzene to the oxidant is 1:1-3.
9. The method according to any one of claims 1 to 8, characterized in that: The substituted benzene is as shown in formula (I), Wherein, R is a C1-C10 alkyl group, a C6-C15 aryl group, an acyl group, an ether group or a halogen group.
10. The method according to any one of claims 1 to 8, characterized in that: The oxidant is one of hexamethylenetetramine, potassium permanganate, potassium dichromate, chromium trioxide and ruthenium tetroxide, or any combination of two or more thereof.
11. The method according to any one of claims 1 to 8, characterized in that: The organic solvent is one of trifluoroacetic acid, difluoroacetic acid, monofluoroacetic acid, acetic acid and propionic acid, or any combination of two or more thereof.
12. The method according to any one of claims 1 to 11, characterized in that: The flow rate of the continuous flow entering the microreactor is 0.05-0.2 mL / min, preferably 0.8-1.2 mL / min.
13. The method according to any one of claims 1 to 12, characterized in that: The reaction conditions in the microreactor include: a temperature of 60-120° C., preferably 95-105° C.; and a reaction time of 5-30 min, preferably 10-20 min.