Continuous preparation method of m-hydroxy-N, N-diethylaniline

Abstract

The invention relates to a continuous preparation method of m-hydroxy-N, N-diethylaniline, which comprises the following steps: respectively introducing an m-aminophenol aqueous solution and halogenated hydrocarbon into a first microreactor, heating, mixing and reacting to obtain a mixed solution A1, respectively introducing the mixed solution A1 and a first part of acid-binding agent into a second microreactor, mixing, heating and reacting to obtain a mixed solution A2, respectively introducing the mixed solution A2 and a second part of acid-binding agent into a third micro-reactor for mixed reaction to obtain a mixed solution B1, then respectively carrying out mixed reaction on the mixed solution B1 and a third part of acid-binding agent in a fourth micro-reactor to obtain a mixed solution C1, crystallizing the mixed solution C1 to obtain a m-hydroxy-N, N-diethylaniline crude product, and carrying out crystallization on the m-hydroxy-N, N-diethylaniline crude product to obtain m-hydroxy-N, N-diethylaniline. And decolorizing the crude product, recrystallizing and filtering to obtain the finished product m-hydroxy-N, N-diethylaniline. Two-channel continuous feeding is adopted, so that a reaction system is mixed more uniformly, the acid-binding agent is continuously introduced into the microreactor in batches, the defect of non-uniform dispersion of the acid-binding agent is reduced, generation of by-products is inhibited, and efficient and rapid production is realized.

Description

Technical Field

[0001] The invention relates to a continuous preparation method of aromatic amine alkylates, in particular to a continuous preparation method of m-hydroxy-N,N-diethylaniline, belonging to the technical field of organic chemical synthesis. Background Art

[0002] Meta-hydroxy-N,N-diethylaniline, with a molecular formula of C10H15NO, is also known as 3-hydroxy-N,N-diethylaniline, meta-diethylaminophenol, and belongs to conjugated organic substances such as aniline derivatives and azo compounds. There is a large conjugated π bond in the molecular structure. When light of different wavelengths is irradiated on the conjugated π bond, the conjugated π bond will absorb the energy of a certain wavelength and show a color complementary to the color of the absorbed wavelength. Meta-hydroxy-N,N-diethylaniline is an important intermediate for synthetic dyes and color developers. It can be used as an intermediate for substances such as alkaline rose essence, acid pink, and disperse fluorescent dyes. It is also an intermediate for the synthesis of ultraviolet absorber DHHB (UVA-PLUS, diethylamino hydroxybenzoyl hexyl benzoate), and is also one of the drug intermediates.

[0003] At present, there are three main methods for synthesizing m-hydroxy-N,N-diethylaniline: Method 1: m-aminophenol and halogenated hydrocarbon are heated and mixed with water to react to generate a mixture 1 containing a crude product of m-hydroxy-N,N-diethylaniline; the mixture 1 is slowly mixed with an acid-binding agent to obtain a mixture 2; the mixture 2 is kept at 100°C to 165°C; the mixture 2 is cooled, the pH value of the mixture 2 is adjusted to 5.5 to 6.5, and then filtered to obtain a solid, which is a crude product; the crude product is distilled to obtain a fraction of 165°C to 180°C, which is the m-hydroxy-N,N-diethylaniline. This preparation method is an intermittent preparation method with low production efficiency and high reaction pressure. The raw materials are added once and then the acid-binding agent is slowly added. The acid-binding agent is unevenly dispersed, forming a local over-alkali, resulting in side reactions, thereby affecting the product yield and quality.

[0004] Method 2: Sodium m-aminobenzenesulfonate and ethyl chloride are used as the main raw materials. After alkylation reaction, the intermediate material 3-N, N-diethylbenzenesulfonate (referred to as alkylate) is obtained by desalting and stratification; the alkylate is then subjected to alkali fusion reaction (the alkali fusion reaction is carried out in the medium of potassium hydroxide, sodium hydroxide and liquid alkali), acid precipitation, dehydration, and distillation to obtain the product. This preparation method is an intermittent preparation method with low production efficiency and long process route. In addition, it contains a high-temperature alkali fusion process. There are many side reactions in the whole process, and a large amount of three wastes are generated. The yield and product quality are both low.

[0005] Method 3: m-ethoxy-N, N-diethylaniline, protonic acid and iodide salt are used as raw materials, and water is used as solvent for heating and reflux reaction; the molar ratio of m-ethoxy-N, N-diethylaniline and iodide salt is 1:1~1.5, the molar ratio of protonic acid to m-ethoxy-N, N-diethylaniline is 1:0.1~0.2, and the reaction time is 4~6h; after the reaction, the obtained reaction product is extracted by alkali washing, neutralized with water phase and dehydrated to obtain m-hydroxy-N, N-diethylaniline. This preparation method is an intermittent preparation method with low production efficiency and high raw material cost, and is not suitable for industrialization.

[0006] The above preparation methods are all intermittent preparation methods with low production efficiency and a one-time mixing reaction. During the preparation process, the materials are easily unevenly dispersed and by-products are generated. Summary of the invention

[0007] The invention provides a continuous preparation method of m-hydroxy-N,N-diethylaniline to overcome the drawbacks of the prior art. Dual-channel continuous feeding is adopted to make the reaction system more evenly mixed, and an acid-binding agent is continuously introduced into a continuous flow microreactor in batches, thereby reducing the drawback of uneven dispersion of the acid-binding agent, inhibiting the generation of by-products, and realizing efficient and rapid production.

[0008] The technical solution adopted by the present invention to solve the technical problem is: A continuous preparation method of m-hydroxy-N,N-diethylaniline, the preparation method comprising the following steps: a. Mix pure water and m-aminophenol, and heat to T0 of 60-80°C under nitrogen protection to generate a m-aminophenol aqueous solution; b. The halogenated hydrocarbon and the m-aminophenol aqueous solution are respectively introduced into the first microreactor, mixed and heated to T1 of 100-150° C., preferably 100-120° C., the pressure P1 in the microreactor is controlled to be 0.8MPa-1.2MPa, preferably 1.0MPa-1.2MPa, and the mixture stays in the first microreactor for a certain time to obtain a mixed solution A1, and the pH1 at the outlet of the first microreactor is 1-7, preferably 1-3; c. The mixed solution A1 and the first part of the acid binding agent are respectively introduced into the second microreactor, mixed and heated to T2 of 100-150° C., preferably 100-120° C., the pressure P2 in the microreactor is controlled to be 0.8MPa-1.2MPa, preferably 1.0MPa-1.2MPa, and the mixed solution A2 is obtained after staying in the second microreactor for a certain period of time, and the pH2 at the outlet of the second microreactor is 3-7, preferably 4-5; d. The mixed solution A2 and the second part of the acid binding agent are respectively introduced into the third microreactor, mixed and heated to T3 of 100-150° C., preferably 100-120° C., the pressure in the microreactor is controlled to be P3=0.8MPa-1.2MPa, preferably 1.0MPa-1.2MPa, and the mixed solution stays in the second microreactor for a certain time to obtain a mixed solution B1, and the pH value at the outlet of the third microreactor is 3-7, preferably 5-6; e. The mixed solution B1 and the third part of the acid binding agent are respectively introduced into the fourth microreactor, mixed and heated to T4 of 100-150°C, the pressure P4 in the microreactor is controlled to be 0.8MPa-1.2MPa, and the mixed solution stays in the second microreactor for a certain time to obtain a mixed solution C1, and the pH value at the outlet of the fourth microreactor is 3-7; f. The mixed liquid C1 enters the crude product crystallization kettle, under inert gas protection, the pH value is adjusted to 6±0.5, the temperature is lowered to 20~40°C, and the crude product of m-hydroxy-N,N-diethylaniline is obtained by filtration; g. The crude product of m-hydroxy-N,N-diethylaniline enters the decolorization kettle, and the solvent is added, the inert gas is protected, the temperature is raised to dissolve, and the hot water is washed. After the water layer is separated by standing, activated carbon is added, and the temperature is kept at 60-80°C for 0.5-1h for decolorization, and hot filtration is performed. The decolorization temperature is preferably 50-80°C; h. The filtrate enters the crystallization kettle, under inert gas protection, the temperature is lowered to 0~5℃, kept warm for 0.5~1h, cold filtered, washed 2~3 times with cold solvent to obtain a wet product, and the filtrate is used; i. The wet product is dried under reduced pressure to obtain the finished product m-hydroxy-N,N-diethylaniline. The drying temperature is 50~65℃ and the vacuum degree is -0.095~-0.098MPa. Vacuum drying can effectively avoid product oxidation, and the drying temperature should be controlled below the melting point of the product.

[0009] j. The crystallization mother liquor is subjected to reduced pressure distillation to recover the solvent, and the vacuum degree is controlled at -0.08~-0.09Mpa. After the solvent is recovered, the vacuum degree is controlled at 160~180℃ and the vacuum degree is controlled at -0.095~-0.098MPa to recover m-hydroxy-N,N-diethylaniline. Low-temperature solvent recovery is beneficial to prevent high-temperature polymerization of the product.

[0010] In the above-mentioned continuous preparation method of m-hydroxy-N,N-diethylaniline, in step a, the mass ratio of m-aminophenol to pure water is 1:(1.0-2.0), and the preferred mass ratio is 1:(1.25-1.50).

[0011] In the above-mentioned continuous preparation method of m-hydroxy-N,N-diethylaniline, in the step b, the halogenated hydrocarbon is one or more of ethyl chloride, ethyl bromide, and ethyl iodide.

[0012] The continuous preparation method of m-hydroxy-N,N-diethylaniline, in the step b, the halogenated hydrocarbon and the m-aminophenol aqueous solution are quantitatively pumped into the first microreactor by a high-pressure metering pump through a mass flow meter, and the mass flow rate of the m-aminophenol aqueous solution is Q A1-1 =1~40g / min, preferably 5~15 g / min, halogenated hydrocarbon mass flow rate Q A1-2 =1~40g / min, preferably 5~15 g / min.

[0013] In the above-mentioned continuous preparation method of m-hydroxy-N,N-diethylaniline, in the step c, the mass flow rate Q of the mixed solution A1 is A2-1 =Q A1-1 +Q A1-2 ; The mass flow rate Q of the first part of the acid binding agent A2-2 =1~40g / min, preferably 2~10g / min.

[0014] The continuous preparation method of m-hydroxy-N,N-diethylaniline, in step d, the mass flow rate Q of the mixed solution A2 is B1-1 =Q A2-1 +Q A2-2 The mass flow rate Q of the second part of the acid binding agent B1-2 =1~40g / min, preferably 2~10g / min.

[0015] In the above-mentioned continuous preparation method of m-hydroxy-N,N-diethylaniline, in the step e, the mass flow rate Q of the mixed solution B1 is C1-1 =Q B1-1 +Q B1-2 The mass flow rate Q of the third part of the acid binding agent C1-2 =1~40g / min, preferably 2~10 g / min.

[0016] In the continuous preparation method of the above-mentioned m-hydroxy-N,N-diethylaniline, the molar ratio of m-aminophenol: water: halogenated hydrocarbon: acid binding agent is 1: (10-15): (2-3): (1.5-2.5), the molar amount of the acid binding agent is the total amount of the three parts of acid binding agent, and the molar ratio of the first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent is 1: (0.4-0.8): (0.2-0.5).

[0017] In the continuous preparation method of m-hydroxy-N,N-diethylaniline, the first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent are all one or more of sodium hydroxide aqueous solution, ammonia water and sodium carbonate aqueous solution, the acid binding agent concentration selection range is 5% to 40% by mass concentration, the mass concentrations of the first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent show a gradually decreasing trend, the acid binding agent is preferably sodium hydroxide aqueous solution, the mass concentration of the first part of the acid binding agent is preferably 30% to 40%, the mass concentration of the second part of the acid binding agent is preferably 20% to 30%, and the mass concentration of the third part of the acid binding agent is preferably 10% to 20%.

[0018] The above-mentioned continuous preparation method of m-hydroxy-N,N-diethylaniline, in the step g, the solvent is one or more of methanol, ethanol, toluene, and xylene, the mass ratio of the crude m-hydroxy-N,N-diethylaniline to the solvent is 1:(1-2), preferably 1:(1.2-1.5); the mass ratio of the crude m-hydroxy-N,N-diethylaniline to the activated carbon is 1:(0.001-0.01).

[0019] Each material is quantitatively introduced into the corresponding micro-reaction channel through a high-pressure metering pump via a mass flow meter for full mixing and reaction. The micro-reactor is equipped with a jacket, and heat transfer oil is introduced into the jacket for heating and heat preservation.

[0020] The beneficial effects of the present invention are: In the preparation method of the present invention, a dual-channel microreactor is selected to replace a reactor to realize continuous flow in and out, and the microreactor has a smaller unit capacity, and the impact caused by special working conditions such as leakage is lower. The dual-channel continuous feeding makes the reaction system more evenly mixed, avoids the side reaction caused by the excessive concentration of the acid-binding agent in a local area due to the large amount of acid-binding agent added at one time, and increases the content of m-hydroxy-N, N-diethylaniline in the crude product. Avoid using the distillation method during refining, avoid the product polymerization coking loss caused by the high temperature of distillation, and the finished product has higher purity, and the quality and appearance are significantly improved.

[0021] In the preparation method of the present invention, the acid-binding agent is selected to be continuously fed in stages, and the concentration of the acid-binding agent is gradually changed. At the same time, sufficient continuous reaction time is reserved after the addition of the acid-binding agent, which can ensure that the aminoalkylation in the front stage is carried out quickly and avoid the occurrence of incomplete alkylation, and can effectively avoid the impact of the acid-binding agent entering the system in the rear stage of the reaction on the reaction system, reduce the occurrence of phenolic hydroxyl alkylation side reactions, improve the reaction selectivity, reduce the occurrence of side reactions, and increase the content of hydroxyl-N,N-diethylaniline in the crude product.

[0022] In this synthesis scheme, the traditional vacuum distillation refining scheme is not adopted, but the decolorization and recrystallization scheme is selected. Firstly, the high temperature of vacuum distillation will cause high-temperature polymerization of m-hydroxy-N,N-diethylaniline to generate dimers, and there will be more residual products in the distillation kettle, resulting in loss of yield, and the solid waste of the distillation kettle residue is difficult to handle; secondly, the crude product quality of this synthesis scheme is better than that of the traditional process, the decolorization and recrystallization are less difficult, and the yield loss is less after the application of toluene washing solution and the recovery of toluene mother liquor distillation kettle residue. The product formed by recrystallization is crystalline particles, which is more convenient to use than the existing hot filling and melt slicing packaging methods of industrial products. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a reaction flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention adopts halogenated hydrocarbon and m-aminophenol aqueous solution to prepare m-hydroxy-N,N-diethylaniline, and the reaction occurring in the reaction process is as follows: 1. Main reaction:

[0025] (II) Side reactions may also occur during the reaction, mainly: Incomplete alkylation reaction:

[0026] Alkylation reaction of phenolic hydroxyl groups:

[0027] In order to suppress the occurrence of side reactions, the acid-binding agent enters the microreactor channel continuously in stages. The mass concentration of the first part of the acid-binding agent is preferably 30-40%, and the mass flow rate Q entering the microreactor channel is A2-2 = 1 ~ 40g / min, preferably 2 ~ 10g / min, more preferably 5 ~ 6g / min; the mass concentration of the second part of the acid binding agent is preferably 20 ~ 30%, the mass flow rate Q entering the microreactor channel B1-2 = 1 ~ 40g / min, preferably 2 ~ 10g / min, more preferably 3 ~ 6g / min; the mass concentration of the third part of the acid binding agent is preferably 10 ~ 20%, the mass flow rate Q entering the microreactor channel C1-2=1~40g / min, preferably 2~10g / min, more preferably 3~8g / min, and the molar ratio of the three parts of the acid binding agent is controlled to be 1: (0.4~0.8): (0.2~0.5), and the molar ratio of the acid binding agent refers to the molar ratio of the effective ingredient in the acid binding agent. Since hydrogen chloride exists in a large amount in the reaction system when the first part of the acid binding agent is added, the use of a high concentration of acid binding agent can accelerate the reaction process, shorten the reaction time, and at this time, it is not easy to cause local over-alkalinity caused by uneven dispersion. When the second and third parts of the acid binding agent are added, since the concentration of hydrogen chloride in the system decreases, adding a high concentration of acid binding agent will easily cause local over-alkalinity caused by uneven dispersion, thereby causing a phenolic hydroxyl alkylation side reaction, so at this time, the acid binding agent concentration is gradually reduced to avoid the occurrence of local over-alkalinity and inhibit the occurrence of a phenolic hydroxyl alkylation side reaction.

[0028] Mass flow rate Q of m-aminophenol aqueous solution A1-1 =1~40g / min, preferably 5~15 g / min, halogenated hydrocarbon mass flow rate Q A1-2 =1~40g / min, preferably 5~15 g / min. With the addition of the acid binding agent, the flow rate is constantly increasing during the entire continuous flow process. The reaction speed is faster in the initial stage of the reaction. As the reaction progresses, the reaction speed decreases in the later stage. The residence time of the reaction system in the microreactor is gradually extended. The residence time of the first microreactor is H1=0.5~1h, the residence time of the second microreactor is H2=1~2h, the residence time of the third microreactor is H3=2~4h, and the residence time of the fourth microreactor is H4=4~8h.

[0029] The present invention will be further described below in conjunction with the embodiments and drawings. Example 1

[0030] Add 750 g of pure water to a four-necked flask, start stirring, add 500 g of m-aminophenol, introduce nitrogen protection, start heating to 80 ° C, and then pump it into the first microreactor channel I through a high-pressure metering pump to control the mass flow rate Q A1-1 =12.5g / min, and at the same time, 600g of ethyl chloride is pumped into the first microreactor channel II through a proportional pump to control the mass flow rate Q A1-2 =6g / min, to achieve full mixing reaction of ethyl chloride and m-aminophenol aqueous solution in the first microreactor, residence time H1=0.5h, to obtain mixed solution A1, during the mixing reaction, heat transfer oil is introduced into the jacket of the first microreactor, the system is heated to 100°C, and the pressure in the first microreactor is 1.0MPa; The outlet pH value is 1, the outlet valve of the first microreactor is opened, and the mixed solution A1 in the first microreactor is passed into the channel I of the second microreactor. The mass flow rate Q of the mixed solution A1 is controlled by a mass flow meter. A2-1=18.5g / min, 600g of sodium hydroxide solution with a mass content of 30% is introduced into the second microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled by a mass flow meter A2-2 =6g / min, the two are fully mixed in the second microreactor to obtain a mixed solution A2, the residence time H2=1h, during the reaction, the second microreactor jacket is introduced with heat transfer oil, the system is heated to 100°C, and the pressure is 1.0MPa; The pH value of the outlet of the second microreactor is 4, and the outlet valve of the second microreactor is controlled to pass the reaction mixture A2 in the second microreactor into the channel I of the third microreactor to control the mass flow rate QB of the mixture A2 1-1 =24.5g / min, 500g of 20% sodium hydroxide solution is introduced into the third microreactor channel II through a proportional pump to control the mass flow rate Q B1-2 =5g / min, the mixed solution A2 and 20% sodium hydroxide solution are fully mixed in the third microreactor, and the residence time H3=2h to obtain the mixed solution B1. During the reaction, the third microreactor jacket is introduced with heat transfer oil, and the system is heated to 100°C and the pressure is 1.0MPa; The pH value of the outlet of the third microreactor is controlled to be 6, and the outlet valve of the third microreactor is controlled to pass the mixed liquid B1 in the third microreactor into the channel I of the fourth microreactor to control the mass flow rate QC of the mixed liquid B1 1-1 =29.5g / min, 800g of 10% sodium hydroxide solution is introduced into the fourth microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled C1-2 =8g / min; the two were mixed and reacted in the fourth microreactor, and the residence time H4=6h. During the reaction, heat transfer oil was introduced into the jacket of the fourth microreactor, and the system was heated to 100°C and the pressure was 1.0MPa; The outlet pH value is 6, the outlet valve of the fourth microreactor is controlled, the fourth microreactor liquid is cooled to 70°C through a condenser and passed into a four-necked bottle (crude product crystallization kettle), nitrogen is passed in for protection, stirring is started, the pH value is adjusted to 7 with 10% sodium hydroxide solution, the temperature is continued to be lowered to 30°C, and a black crude product is obtained by filtration; In a four-necked flask, 1000 g of toluene (toluene washing liquid) was added, a batch of crude product was added, 10 g of activated carbon was added, nitrogen was introduced for protection, the temperature was raised to 80°C, the temperature was kept for 0.5 h, and hot filtering was performed; the filtrate was poured into a four-necked bottle, nitrogen was introduced for protection, the temperature was slowly lowered to 0°C, the temperature was kept for 1 h, and cold filtering was performed; the filter cake was washed with 1000 g of cold toluene twice, the washing liquid was applied, and the wet product was dried under reduced pressure to obtain 676.87 g of light purple off-white crystalline solid; the toluene mother liquor was distilled under reduced pressure to recover the crude product, and then after decolorization and recrystallization, 45.49 g of light purple off-white crystalline solid was obtained, and a total of 722.36 g of product was obtained, the product purity (GC) was 99.38%, the freezing point was 72.0°C, and the yield was 95.42%. Example 2

[0031] Add 750 g of pure water to a four-necked flask, start stirring, add 500 g of m-aminophenol, introduce nitrogen protection, start heating to 80 ° C, and then pump it into the first microreactor channel I through a high-pressure metering pump to control the mass flow rate Q A1-1 =12.5g / min, and at the same time, 1000g of ethyl bromide is pumped into the first microreactor channel II through a proportional pump to control the mass flow rate Q A1-2 =10g / min, to achieve full mixing reaction of ethyl bromide and m-aminophenol aqueous solution in the first microreactor, residence time H1=0.5h, to obtain mixed solution A1, during the mixing reaction, heat transfer oil is introduced into the jacket of the first microreactor, the system is heated to 100°C, as the temperature rises, ethyl chloride and water are continuously vaporized, the pressure in the first microreactor rises, and the pressure in the first microreactor is 1.0MPa; The outlet pH value is 1, the outlet valve of the first microreactor is opened, and the mixed solution A1 in the first microreactor is passed into the channel I of the second microreactor. The mass flow rate Q of the mixed solution A1 is controlled by a mass flow meter. A2-1 =22.5g / min, 500g of sodium hydroxide solution with a mass content of 40% is introduced into the second microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled by a mass flow meter A2-2 =5g / min, the two are fully mixed in the second microreactor to obtain a mixed solution A2, the residence time H2=1h, during the reaction, the second microreactor jacket is introduced with heat transfer oil, the system is heated to 100°C, and the pressure is 1.0MPa; The pH value of the outlet of the second microreactor is 4, and the outlet valve of the second microreactor is controlled to pass the reaction mixture A2 in the second microreactor into the channel I of the third microreactor to control the mass flow rate QB of the mixture A2 1-1 =27.5g / min, 300g of sodium hydroxide solution with a mass content of 30% is introduced into the third microreactor channel II through a proportional pump to control the mass flow rate Q B1-2=3g / min, the mixed solution A2 and 30% sodium hydroxide solution are fully mixed in the third microreactor, and the residence time H3=2h to obtain the mixed solution B1. During the reaction, the third microreactor jacket is introduced with heat transfer oil, and the system is heated to 100°C and the pressure is 1.0MPa; The outlet pH value of the third microreactor is 6, and the outlet valve of the third microreactor is controlled to pass the mixed solution B1 in the third microreactor into the channel I of the fourth microreactor to control the mass flow rate QC of the mixed solution B1 1-1 =30.5g / min, 350g of 20% sodium hydroxide solution is introduced into the fourth microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled C1-2 =3.5g / min; the two were mixed and reacted in the fourth microreactor, and the residence time H3=4h. During the reaction, the fourth microreactor jacket was introduced with heat transfer oil, and the system was heated to 100°C and the pressure was 1.0MPa; The outlet pH value is 6, the outlet valve of the fourth microreactor is controlled, the fourth microreactor liquid is cooled to 70°C through a condenser and passed into a four-necked bottle (crude product crystallization kettle), nitrogen is passed in for protection, stirring is started, the pH value is adjusted to 7 with 10% sodium hydroxide solution, the temperature is continued to be lowered to 30°C, and a black crude product is obtained by filtration; In a four-necked flask, 1000 g of toluene (toluene washing liquid) was added, a batch of crude product was added, 10 g of activated carbon was added, nitrogen was introduced for protection, the temperature was raised to 80°C, the temperature was kept for 0.5 h, and hot filtering was performed; the filtrate was poured into a four-necked bottle, nitrogen was introduced for protection, the temperature was slowly lowered to 0°C, the temperature was kept for 1 h, and cold filtering was performed; the filter cake was washed with 1000 g of cold toluene twice, the washing liquid was applied, and the wet product was dried under reduced pressure to obtain 673.27 g of a light purple off-white crystalline solid; the toluene mother liquor was distilled under reduced pressure to recover the crude product, and then after decolorization and recrystallization, 45.67 g of a light purple off-white crystalline solid was obtained, and a total of 718.94 g of the product was obtained, the product purity (GC) was 99.23%, the freezing point was 72.8°C, and the yield was 94.96%. Example 3

[0032] Add 750 g of pure water to a four-necked flask, start stirring, add 500 g of m-aminophenol, introduce nitrogen protection, start heating to 80 ° C, and then pump it into the first microreactor channel I through a high-pressure metering pump to control the mass flow rate Q A1-1 =12.5g / min, and at the same time, 600g of ethyl chloride is pumped into the first microreactor channel II through a proportional pump to control the mass flow rate Q A1-2=6g / min, to achieve full mixing reaction of ethyl chloride and m-aminophenol aqueous solution in the first microreactor, residence time H1=0.5h, to obtain mixed solution A1, during the mixing reaction, heat transfer oil is introduced into the jacket of the first microreactor, the system is heated to 110°C, as the temperature rises, ethyl chloride and water are continuously vaporized, the pressure in the first microreactor rises, and the pressure in the first microreactor is 1.1MPa; The outlet pH value is 1, the outlet valve of the first microreactor is opened, and the mixed solution A1 in the first microreactor is passed into the channel I of the second microreactor. The mass flow rate Q of the mixed solution A1 is controlled by a mass flow meter. A2-1 =18.5g / min, 600g of sodium hydroxide solution with a mass content of 30% is introduced into the second microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled by a mass flow meter A2-2 =6g / min, the two are fully mixed in the second microreactor to obtain a mixed solution A2, the residence time H2=1h, during the reaction, the second microreactor jacket is introduced with heat transfer oil, the system is heated to 110°C, and the pressure is 1.1MPa; The pH value of the outlet of the second microreactor is 4, and the outlet valve of the second microreactor is controlled to pass the reaction mixture A2 in the second microreactor into the channel I of the third microreactor to control the mass flow rate QB of the mixture A2 1-1 =24.5g / min, 600g of 20% sodium hydroxide solution is introduced into the third microreactor channel II through a proportional pump to control the mass flow rate Q B1-2 =6g / min, the mixed solution A2 and 20% sodium hydroxide solution are fully mixed in the third microreactor, and the residence time H3=2h to obtain the mixed solution B1. During the reaction, the third microreactor jacket is introduced with heat transfer oil, and the system is heated to 110°C and the pressure is 1.1MPa; The outlet pH value of the third microreactor is 6, and the outlet valve of the third microreactor is controlled to pass the mixed solution B1 in the third microreactor into the channel I of the fourth microreactor to control the mass flow rate QC of the mixed solution B1 1-1 =30.5g / min, 480g of 10% sodium hydroxide solution is introduced into the fourth microreactor channel II through a high-pressure metering pump, and the mass flow rate Q is controlled C1-2 =4.8g / min; the two are mixed and reacted in the fourth microreactor, and the residence time H3=8h. During the reaction, the fourth microreactor jacket is introduced with heat transfer oil, and the system is heated to 110°C and the pressure is 1.1MPa; The outlet pH value is 6, the outlet valve of the fourth microreactor is controlled, the fourth microreactor liquid is cooled to 70°C through a condenser and passed into a four-necked bottle (crude product crystallization kettle), nitrogen is passed in for protection, stirring is started, the pH value is adjusted to 7 with 10% sodium hydroxide solution, the temperature is continued to be lowered to 30°C, and a black crude product is obtained by filtration; 1000g of xylene (xylene washing liquid) was added to a four-necked flask, a batch of crude product was added, 10g of activated carbon was added, nitrogen was introduced for protection, the temperature was raised to 80°C, the temperature was kept for 0.5h, and hot filtering was performed; the filtrate was poured into a four-necked bottle, nitrogen was introduced for protection, the temperature was slowly lowered to 0°C, the temperature was kept for 1h, and cold filtering was performed; 1000g of cold xylene was used to wash the filter cake twice, the washing liquid was applied, and the wet product was dried under reduced pressure to obtain 672.5g of light purple off-white crystalline solid; the xylene mother liquor was distilled under reduced pressure to recover the crude product, and then after decolorization and recrystallization, 45.03g of light purple off-white crystalline solid was obtained, and a total of 717.53g of product was obtained, the product purity (GC) was 99.17%, the freezing point was 72.5°C, and the yield was 94.78%.

Claims

1. A continuous preparation method of m-hydroxy-N,N-diethylaniline, characterized in that: The preparation method comprises the following steps: a. Mix pure water and m-aminophenol, and heat to T0 of 60-80°C under nitrogen protection to generate a m-aminophenol aqueous solution; b. The halogenated hydrocarbon and m-aminophenol aqueous solutions are introduced into the first microreactor respectively, mixed and heated to T1 of 100-150°C, the pressure P1 in the microreactor is controlled to be 0.8MPa-1.2MPa, and the mixture stays in the first microreactor for a certain period of time to obtain a mixed solution A1, and the pH1 at the outlet of the first microreactor is 1-7; c. The mixed solution A1 and the first part of the acid binding agent are respectively introduced into the second microreactor, mixed and heated to T2 of 100-150°C, the pressure P2 in the microreactor is controlled to be 0.8MPa-1.2MPa, and the mixed solution A2 is obtained after staying in the second microreactor for a certain period of time, and the pH value of the outlet of the second microreactor is 3-7; d. The mixed solution A2 and the second part of the acid binding agent are respectively introduced into the third microreactor, mixed and heated to T3 of 100-150°C, the pressure in the microreactor is controlled to be P3=0.8MPa-1.2MPa, and the mixed solution stays in the second microreactor for a certain time to obtain a mixed solution B1, and the pH value at the outlet of the third microreactor is 3-7; e. The mixed solution B1 and the third part of the acid binding agent are respectively introduced into the fourth microreactor, mixed and heated to T4 of 100-150°C, the pressure P4 in the microreactor is controlled to be 0.8MPa-1.2MPa, and the mixed solution stays in the second microreactor for a certain time to obtain a mixed solution C1, and the pH value at the outlet of the fourth microreactor is 3-7; f. The mixed liquid C1 enters the crude product crystallization kettle, under inert gas protection, the pH value is adjusted to 6±0.5, the temperature is lowered to 20~40°C, and the crude product of m-hydroxy-N,N-diethylaniline is obtained by filtration; g. The crude product of m-hydroxy-N,N-diethylaniline enters the decolorization kettle, and the solvent is added. Under inert gas protection, the temperature is raised to dissolve, and hot water is washed. After the water layer is separated by standing, activated carbon is added, and the temperature is kept at 60-80°C for 0.5-1h for decolorization, and hot filtration is performed; h. The filtrate enters the crystallization kettle, under inert gas protection, the temperature is lowered to 0~5℃, kept warm for 0.5~1h, cold filtered, washed 2~3 times with cold solvent to obtain a wet product, and the washing liquid is applied; i. Drying the wet product under reduced pressure to obtain the finished product m-hydroxy-N,N-diethylaniline; j. The crystallization mother liquor is subjected to reduced pressure distillation to recover the solvent. After the solvent is recovered, m-hydroxy-N,N-diethylaniline is recovered at 160~180°C and vacuum degree -0.095~-0.098MPa.

2. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In the step a, the mass ratio of m-aminophenol to pure water is 1:(1.0-2.0).

3. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In the step b, the halogenated hydrocarbon is one or more of ethyl chloride, ethyl bromide, and ethyl iodide.

4. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 3, characterized in that: In the step b, the halogenated hydrocarbon and the m-aminophenol aqueous solution are quantitatively pumped into the first microreactor by a high-pressure metering pump through a mass flow meter. The mass flow rate of the m-aminophenol aqueous solution is Q A1-1 =1~40g / min, halogenated hydrocarbon mass flow rate Q A1-2 =1~40g / min.

5. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In step c, the mass flow rate Q of the mixed solution A1 is A2-1 = Q A1-1+ Q A1-2 ; The mass flow rate Q of the first part of the acid binding agent A2-2 =1~40g / min.

6. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In step d, the mass flow rate Q of the mixed liquid A2 B1-1 = Q A2-1+ Q A2-2 , the mass flow rate Q of the second part of the acid binding agent B1-2 =1~40g / min.

7. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In step e, the mass flow rate Q of the mixed liquid B1 is C1-1 = Q B1-1+ Q B1-2 , the mass flow rate Q of the third part of the acid binding agent C1-2 =1~40g / min.

8. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: The molar ratio of the m-aminophenol: water: halogenated hydrocarbon: acid binding agent is 1: (10-15): (2-3): (1.5-2.5), the molar amount of the acid binding agent is the total amount of the three parts of the acid binding agent, and the molar ratio of the first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent is 1: (0.4-0.8): (0.2-0.5).

9. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: The first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent are all one or more of sodium hydroxide aqueous solution, ammonia water and sodium carbonate aqueous solution. The concentration of the acid binding agent is selected in the range of 5% to 40% by mass concentration. The mass concentrations of the first part of the acid binding agent, the second part of the acid binding agent and the third part of the acid binding agent show a gradually decreasing trend.

10. The continuous preparation method of m-hydroxy-N,N-diethylaniline according to claim 1, characterized in that: In the step g, the solvent is one or more of methanol, ethanol, toluene, and xylene, and the mass ratio of the crude m-hydroxy-N,N-diethylaniline to the solvent is 1:(1-2); the mass ratio of the crude m-hydroxy-N,N-diethylaniline to the activated carbon is 1:(0.01-0.10).

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