CN106588602A - Method for preparing 2,6-dichlorobenzaldehyde through continuous oxidization of 2,6-dichlorotoluene - Google Patents

Abstract

The invention discloses a method for preparing 2,6-dichlorobenzaldehyde by continuous oxidation of 2,6-dichlorotoluene, which belongs to the technical field of organic synthesis technology. The method uses 2,6-dichlorotoluene compound as raw material, one or more metal ion complexes of cobalt, molybdenum, and bromine as catalyst, hydrogen peroxide as oxidant, and acetic acid as solvent, and the Process technology for preparing 2,6-dichlorobenzaldehyde by oxidation of 2,6-dichlorotoluene. The method has mild conditions, short reaction time, high raw material utilization rate, effective control in the reaction process, safety and stability, continuous operation and high production efficiency.

Description

A kind of method for preparing 2,6-dichlorobenzaldehyde by continuous oxidation of 2,6-dichlorotoluene

technical field

The invention belongs to the technical field of organic synthesis technology, and relates to a method for preparing 2,6-dichlorobenzaldehyde by continuous oxidation of 2,6-dichlorotoluene under liquid-phase reaction conditions, more specifically, using 2,6-dichlorobenzaldehyde Chlorotoluene is used as a substrate, hydrogen peroxide is used as an oxidant, one or several metal ion complexes of cobalt, molybdenum, and bromine are used as catalysts, and monocarboxylic acids are used as solvents. Continuously prepare 2 in tubular reactors with different microstructures, 6-Dichlorobenzaldehyde product.

Background technique

2,6-Dichlorobenzaldehyde, molecular formula: C ₇ H ₄ Cl ₂ O, molecular weight 175.01, the finished product is white to yellow needle-like crystal, with strong odor, melting point 67-71 ℃, soluble in ethanol, ether, petroleum Organic solvents such as ether, 2,6-dichlorobenzaldehyde is one of the important raw materials for the synthesis of fine chemicals, and is used for the synthesis of dyes, pesticides and pharmaceutical intermediates. In the pesticide industry, it is mainly used to synthesize the intermediate of the herbicide dichonil and the insecticide diflubenzuron; in the dye industry, it is mainly used to synthesize the intermediate of dye acid medium bleaching blue B; in the pharmaceutical industry, it is mainly used to synthesize dichlorobenzene Sodium azole penicillin.

The current synthesis and production methods of 2,6-dichlorobenzaldehyde include toluene direct chlorination method, nitrotoluene method, o-nitrotoluene method, p-tert-butyltoluene method, o-toluenesulfonyl chloride decomposition method, etc.:

(1) Chlorination hydrolysis

Using 2,6-dichlorotoluene as the starting material, 2,6-dichlorobenzaldehyde was synthesized by chlorination and hydrolysis. The disadvantage of this reaction is that the chlorination time is too long, and the degree of chlorination is difficult to control, and a large amount of by-products are easily produced.

(2) Chlorination and hydrolysis of nitrotoluene

Using 2-chloro-6-nitrotoluene as the starting material, heating and melting in an oil bath, passing dry chlorine gas under light, controlling the reaction temperature at 180-200°C, and the reaction time is about 15 hours to obtain 2,6 - mixtures of dichlorobenzylidene dichlorides. Then add the above mixture, p-toluenesulfonic acid monohydrate and zinc chloride into the reactor according to the appropriate proportion, heat it up to 110-120° C. under stirring, and obtain 2,6-dichlorobenzaldehyde after post-treatment. However, there are obvious defects in the above-mentioned production method: difficult production control, low output, high cost, and can not be suitable for its market demand.

The method described above optimizes and improves the preparation of 2,6-dichlorobenzaldehyde by oxidation of 2,6-dichlorotoluene from different angles, but there are still some problems to be solved: firstly, batch kettles are still mainly used in large-scale production Batch production; secondly, in the above-mentioned method, large-scale chlorination and then hydrolysis preparation are still the main method, and the degree of chlorination is difficult to control, which easily causes the increase of by-products. The continuous oxidation of 2,6-dichlorotoluene to synthesize 2,6-dichlorobenzaldehyde using a continuous flow tubular reactor with a specific structure can solve many shortcomings of the existing technology in many ways.

Tubular reactor is a general term for small reactors with microstructure. Compared with conventional reactors, tubular reactors have small volume, large specific surface area, easy enlargement, continuous process, good rapid mixing effect, and good heat transfer effect. With the characteristics of high temperature and high pressure resistance, the continuous flow tube reactor with a specific structure can effectively control the mixing of reaction materials, mass transfer and heat transfer process. By controlling the length of the tubular reactor and the reaction residence time, the distribution of raw materials and products can be further optimized and controllable; by adjusting the flow rate of the raw material pump, the substrate 2,6-dichlorotoluene and the oxidant can enter in proportion The reaction in the tubular reactor greatly reduces the back mixing, further reduces the occurrence of side reactions, the stability of the oxidant and the selectivity of the target product are also greatly improved; by setting the pressure safety valve in the tubular reactor, it can be discharged in time The excess oxidant in the reactor ensures the safety of the reaction and minimizes the risk rate. The method for preparing 2,6-dichlorobenzaldehyde by continuous oxidation of 2,6-dichlorotoluene in a tubular reactor with a specific structure in the present invention has incomparable advantages over traditional batch-type production methods, and can be industrialized Improvement in continuous production provides an important avenue.

Contents of the invention

The present invention aims at the above shortcomings, and provides a method for continuously oxidizing 2,6-dichlorotoluene in a tubular reactor to prepare 2,6-dichlorobenzaldehyde. The method has short reaction time, high production efficiency, greatly optimized mass transfer and heat transfer, and a more stable and controllable reaction process. The further object of the present invention is to realize the stable and controllable continuous oxidation of 2,6-dichlorotoluene and reduce the generation of by-products through the process method of the present invention. Through the intensification of mass transfer and heat transfer process and process optimization, the effective utilization rate of reaction materials can be improved, the usage of oxidants and catalysts can be further reduced, and the use of co-catalysts can be avoided in the reaction process, so as to effectively save production costs and improve the existing industrialization production method.

To achieve the above object, the technical solution adopted in the present invention is:

A method for preparing 2,6-dichlorobenzaldehyde by continuous oxidation of 2,6-dichlorotoluene by a tubular reactor of special structure, carried out according to the following steps:

(1) At first, at room temperature, the substrate 2,6-dichlorotoluene and part of the carboxylic acid solvent are stirred and mixed uniformly with a volume ratio of 1:1, and the oxidant and part of the carboxylic acid solvent are mixed uniformly with a volume ratio of 1:1, and then Mix the metal complex and pour it into the 2,6-dichlorotoluene-carboxylic acid solution, and pour the sodium salt into the hydrogen peroxide-carboxylic acid solution; through the required reaction time, calculate the different flow rates of the two materials, respectively It is continuously pumped into the tubular reactor by the metering pump, preheated and mixed, and then enters the reaction zone for reaction. The reaction temperature is controlled by the external heat exchange system;

(2) Control the molar ratio of the reaction materials by adjusting the flow rate and weighing method, and control the residence time of the mixed reaction of the materials by 60-1800s by changing the inner diameter of the pipe of the tubular reactor from 0.5 to 15mm and the volume from 25 to 750ml; Finally, the product flows out from the end of the reactor into the collection tank, the product is separated by rectification, the unreacted 2,6-dichlorotoluene is recycled, and the product 2,6-dichlorobenzaldehyde is collected after rectification and purification, wherein the target product 2, The yield of 6-dichlorobenzaldehyde can reach 20%-35%.

The catalyst described therein is one or more metal complex catalysts of cobalt, molybdenum and bromine, which mainly include: cobalt acetate, cobalt oxalate, cobalt carbonate, cobalt naphthenate, sodium molybdate, ammonium molybdate, bromide Sodium, ammonium bromide, etc., among which the oil-soluble catalyst is the main one, which can be fully dissolved in 2,6-dichlorotoluene, and the molar ratio of its dosage to the substrate 2,6-dichlorotoluene is (0.005～0.15): 1, wherein the preferred molar ratio is (0.01-0.08):1.

Wherein said oxidizing agent is hydrogen peroxide, and its solution concentration is 5%-50% in terms of mass concentration, preferably 10%-35%. The preferred molar ratio of hydrogen peroxide to the substrate 2,6-dichlorotoluene is (1.0-7.0):1.

The hydrogen peroxide mentioned therein, in the tubular reactor, when the hydrogen peroxide passes through the reactor with a volume of 50ml, the hydrogen peroxide begins to decompose rapidly and release a large amount of molecular oxygen. When it passes through 100ml, it is almost in the form of molecular oxygen. Additional equal-concentration hydrogen peroxide is added to the reaction volume to participate in the reaction again.

The carboxylic acid solvent described therein includes: formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, octanoic acid and the like. Wherein the volume ratio of solvent to 2,6-dichlorotoluene is (1-8):1.

Wherein the reaction temperature is 60-140°C, preferably the reaction temperature is 90-125°C, and the reaction residence time is 60s-1800s.

In a further technical solution, after the reaction is completed, sodium dichloromethane is used to quench the oxidant not involved in the reaction, and then extracted with an organic solvent, and the target product is obtained after separation and purification by distillation.

In the above technical solution, the reaction system includes different functional areas such as a raw material storage tank, a reaction area, and a product collection area. Reactor channel structures include: circular tube straight-through channel structure, round cake pulse variable diameter rectangular flat tube structure, oblique square cake pulse variable diameter rectangular flat tube structure, enhanced mixing circular cake type rectangular flat tube structure and Corning Heart Cell channel structure.

The present invention has the following advantages:

1. The present invention adopts a continuous production method with short reaction time, mild reaction conditions, safe and controllable process, and high production efficiency.

2. By adopting tubular reactors with different structures, the present invention can realize effective control of the reaction process, so that the reaction product stays in the aldol step.

3. Through the enhancement of mass transfer and heat transfer in the reaction process, the reaction rate and the utilization rate of raw materials are greatly improved, and the amount of oxidant and catalyst used is effectively reduced, and the use of co-catalyst is avoided, so that the production cost is effectively reduced saving.

4. The present invention has the advantages of simple operation, wide application range and flexible production, and the production scale can be enlarged through parallel connection of reaction devices.

Description of drawings

Fig. 1 is the process flow diagram of the present invention for the continuous oxidation of 2,6-dichlorotoluene to prepare 2,6-dichlorobenzaldehyde.

Fig. 2 is the device figure of continuous flow tubular reactor used in the present invention: 1,2-raw material tank, 3,4-raw material metering pump, 5-preheating zone, 6,7-reaction zone, 8-product quenching collection area.

Fig. 3 is a schematic diagram of the channel structure of the tubular reactor used in the present invention, wherein a-straight-flow channel structure, b-round cake type pulse variable diameter rectangular flat pipe, c-orthorhombic cake type pulse variable diameter rectangular flat pipe , d-enhanced mixed round pie flat pipe, e-Corning's Heart Cell structure microchannel.

detailed description

Dissolve cobalt acetate and sodium molybdate in the 1# tank containing 2,6-dichlorotoluene and acetic acid, and send it into the 5# preheating reactor through the 3# pump, and the preheating reactor is heated to 50 °C; Dissolve sodium bromide in the 2# tank with hydrogen peroxide and acetic acid, and send it into the 6# preheating reactor through the 4# pump. The preheating reactor is heated to 50 ° C, and then the two preheated materials are transported to 7 In # and 8# reactors, the temperature of the reactors was set at the required temperature for the reaction, and the product flowed out through the 8# reactor, cooled at 0°C, and the resulting product was collected.

The present invention will be described in detail below in conjunction with the examples, but the following examples are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited thereto, and any person familiar with the technical field of the present invention is within the technical scope disclosed in the present invention Within the technical scheme of the present invention and its inventive concept, any equivalent substitution or change shall be covered within the protection scope of the present invention.

Example 1

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3b) straight-line channel + round cake-type pulse variable-diameter rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction residence time. The time is determined, and the heat exchange medium is heat transfer oil.

(2) Dissolve 4.04g of cobalt acetate and 4.04g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.01:1, 4.04g sodium bromide is dissolved in 15% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.01:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.33ml/min and 10.67ml/min, at this time n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=3:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 60°C, and the residence time was 60s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 50.3%, and the yield of 2,6-dichlorobenzaldehyde was 27.1%.

Example 2

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3c) straight-line channel + oblique square cake-type pulse variable-diameter rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction. The residence time is determined, and the heat transfer medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 15% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 8.33ml/min and 16.67ml/min, at this time n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 65°C, and the residence time was 200s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 56.0%, and the yield of 2,6-dichlorobenzaldehyde was 31.7%.

Example 3

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3d) straight-through channel + enhanced mixing round cake type rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction residence time. Make sure that the heat exchange medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 15% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 8.33ml/min and 16.67ml/min, at this time n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=3:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 105°C, and the residence time was 600s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 41.8%, and the yield of 2,6-dichlorobenzaldehyde was 22.2%.

Example 4

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3b) straight-line channel + round cake-type pulse variable-diameter rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction residence time. The time is determined, and the heat exchange medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.33ml/min and 10.67ml/min, at this time n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 105°C, and the residence time was 600s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 51.5%, and the yield of 2,6-dichlorobenzaldehyde was 25.1%.

Example 5

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3c) straight-line channel + oblique square cake-type pulse variable-diameter rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction. The residence time is determined, and the heat transfer medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 8.33ml/min and 16.67ml/min, at this time n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 105°C, and the residence time was 600s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 50.7%, and the yield of 2,6-dichlorobenzaldehyde was 29.1%.

Example 6

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3d) straight-through channel + enhanced mixing round cake type rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction residence time. Make sure that the heat exchange medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.56ml/min and 11.11ml/min respectively. n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 105°C, and the residence time was 900s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 34.7%, and the yield of 2,6-dichlorobenzaldehyde was 25.0%.

Example 7

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipe type is: (3a+3e) straight-through channel + Corningde Heart Cell structure. The inner diameter and volume of the pipe are determined according to the flow rate and reaction residence time. The heat exchange medium For heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.56ml/min and 11.11ml/min respectively. n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 90°C, and the residence time was 900s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 50.8%, and the yield of 2,6-dichlorobenzaldehyde was 28.0%.

Example 8

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3d) straight-through channel + enhanced mixing round cake type rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction residence time. Make sure that the heat exchange medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.56ml/min and 11.11ml/min respectively. n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 120°C, and the residence time was 1200s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 37.9%, and the yield of 2,6-dichlorobenzaldehyde was 26.1%.

Example 9

(1) Device: Refer to Figure 2 to determine the connection mode of the tubular reactor. The pipeline type is: (3a+3c) straight-line channel + oblique square cake-type pulse variable-diameter rectangular flat pipeline. The inner diameter and volume of the pipeline are based on the flow rate and reaction. The residence time is determined, and the heat transfer medium is heat transfer oil.

(2) Dissolve 6.06g of cobalt acetate and 6.06g of sodium molybdate in 200ml of 2,6-dichlorotoluene and 200ml of acetic acid respectively to form a mixed solution. At this time, n(cobalt acetate):n(2,6-dichlorotoluene)= 0.015:1, 6.06g sodium bromide is dissolved in 25% H ₂ O ₂ to form H ₂ O ₂ -acetic acid solution, at this time n(sodium bromide):n(2,6-dichlorotoluene)=0.015:1 , 2,6-dichlorotoluene-acetic acid solution and H ₂ O ₂ -acetic acid solution were injected into the tubular reactor with continuous heat exchange through the constant flow pump at the flow rate of 5.56ml/min and 11.11ml/min respectively. n(H ₂ O ₂ ):n(2,6-dichlorotoluene)=2:1, the microchannel reactor shown in Figure 2 was used, the reaction temperature was controlled at 140°C, and the residence time was 1800s. The outlet material was cooled at 0°C, and the reaction solution was quenched with dichloromethane. After GC analysis, the conversion rate of 2,6-dichlorotoluene was 40.1%, and the yield of 2,6-dichlorobenzaldehyde was 27.2%.

Claims (6)

1. a kind of method that 2,6-DCT continuous oxidation prepares 2,6- dichlorobenzaldehydes, it is characterised in that as steps described below Carry out：

（1）Under room temperature, by substrate 2,6-DCT and part carboxylic acid solvent with volume ratio 1:1 is uniformly mixed, will oxidation Agent and part carboxylic acid solvent are with volume ratio 1:1 mix homogeneously, then pours metal complex mixing into 2,6-DCT-carboxylic acid Solution, sodium salt is poured in hydrogen peroxide-carboxylic acid solution；By the required response time, the not cocurrent flow of two kinds of materials is calculated Speed, continuously squeezes in tubular reactor Jing dosing pump respectively and is reacted into reaction zone after preheated mixing, reaction temperature by Outer loop heat-exchange system is controlled；

（2）The mol ratio of reaction mass is controlled by the method for adjusting flow velocity and weight calculation, by the pipeline for changing tubular reactor 0.5 ~ 15mm of internal diameter, 25 ~ 750ml of volume carry out the time of staying of control material hybrid reaction；After completion of the reaction, product is from reaction Device end exits into collecting tank, and product rectification is separated, unreacted 2,6-DCT circular response, product 2,6- dichloro-benzenes Formaldehyde rectification is collected after purification.

2. the method that a kind of 2,6-DCT continuous oxidation according to claims 1 prepares 2,6- dichlorobenzaldehydes, It is characterized in that described catalyst is cobalt, molybdenum, sodium one or more metal complex catalysts, which mainly includes：Cobalt acetate, Cobalt oxalate, cobalt carbonate, cobalt naphthenate, sodium molybdate, ammonium molybdate, sodium bromide, ammonium bromide etc., wherein based on oil-soluble catalyst, Can fully dissolve in 2,6-DCT, its consumption is existed with the mol ratio of substrate 2,6-DCT（0.005~0.15）: 1, Wherein preferred molar ratio is（0.01~0.08）∶1.

3. the method that a kind of 2,6-DCT continuous oxidation according to claims 1 prepares 2,6- dichlorobenzaldehydes, It is characterized in that described oxidant is hydrogen peroxide, its solution concentration is calculated as 5% ~ 50% with mass concentration, preferred concentration is 15% ~ 30%, hydrogen peroxide with the preferred molar ratio of substrate 2,6-DCT is（1.0~7.0）∶1.

4. the method that a kind of 2,6-DCT continuous oxidation according to claims 1 prepares 2,6- dichlorobenzaldehydes, It is characterized in that described carboxylic acid solvent includes：Formic acid, acetic acid, propanoic acid, butanoic acid, caproic acid, octanoic acid；Wherein solvent and 2,6- dichloros The volume ratio of toluene exists（1~8）∶1.

5. the method that a kind of 2,6-DCT continuous oxidation according to claims 1 prepares 2,6- dichlorobenzaldehydes, It is characterized in that：Reaction temperature is 60 ~ 140 DEG C, and preferable reaction temperature is 95 ~ 125 DEG C, reaction time 60s ~ 1800s.

6. the method that a kind of 2,6-DCT continuous oxidation according to claims 1 prepares 2,6- dichlorobenzaldehydes, It is characterized in that：Total overall reaction process is carried out continuously in the tubular reactor of ad hoc structure, and the response system includes raw material The difference in functionality such as storage tank, reaction zone, product collection region；Channel of reactor structure includes：Pipe once-through type channel design, cake Formula pulse diameter varied narrow rectangular tube road structure, tiltedly side cake formula pulse diameter varied narrow rectangular tube road structure, enhancing mixed type cake formula Narrow rectangular tube road structure, cardioid channel design.