CN110981735A - 6-chloro-2, 4-dinitroaniline mother liquor recycling method - Google Patents
6-chloro-2, 4-dinitroaniline mother liquor recycling method Download PDFInfo
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Abstract
The invention introduces a method for recycling 6-chloro-2, 4-dinitroaniline mother liquor, wherein 2, 4-dinitroaniline is ground and then added into a kettle; adding hydrogen peroxide chlorination process mother liquor and water, heating to 45-60 ℃, and stirring for 1-2 hours under heat preservation; the concentration of hydrochloric acid is 13-25%, and the quantity ratio of 2, 4-dinitroaniline to HCl is controlled to be 1 (4-9); gradually adding 23-27.5% of sodium chlorate solution at the temperature of 40-70 ℃; the molar ratio of the 2, 4-dinitroaniline to the sodium chlorate is 1: 1.2-3; preserving the heat for 1-2 hours at the temperature of 45-70 ℃; separating after the reaction to obtain salt-containing separation liquid and a filter cake; drying the filter cake to obtain the 6-chloro-2, 4-dinitroaniline. The method of the invention uses the mother liquor of the hydrogen peroxide chlorination process as the raw material, and achieves the purposes of environmental protection, energy saving and cost reduction.
Description
Technical Field
The invention relates to the technical field of 6-chloro-2, 4-dinitroaniline, in particular to a method for recycling 6-chloro-2, 4-dinitroaniline mother liquor.
Background
6-chloro-2, 4-dinitroaniline is an important intermediate of disperse dyes and has a large dosage at home and abroad. The method is characterized in that 2, 4-dinitroaniline, hydrochloric acid and water are used as raw materials, hydrogen peroxide is dripped to carry out chlorination preparation, certain salt-free acidic wastewater is generated in the production process, part of the acidic water can be recycled by adopting a hydrogen peroxide chlorination process, and a small amount of acidic water is left.
Disclosure of Invention
The invention aims to solve the technical problem of providing a 6-chloro-2, 4-dinitroaniline mother liquor recycling method, and the aims of environmental protection, energy conservation and cost reduction are achieved. Book (I)
In order to solve the technical problems, the invention adopts the following technical scheme:
a6-chloro-2, 4-dinitroaniline mother liquor recycling method comprises the following steps:
step B1 grinding process: grinding 2, 4-dinitroaniline by a colloid mill, and adding the ground 2, 4-dinitroaniline into a reaction kettle;
step B2, adding mother liquor of a chlorination process containing hydrogen peroxide: adding a chlorination process mother liquor containing hydrogen peroxide and a certain amount of water into a reaction kettle to ensure that the mass concentration of hydrochloric acid is 13-15%; and controlling the amount ratio of the 2, 4-dinitroaniline to the HCl substance to be 2, 4-dinitroaniline: HCl = 1: (4-9);
the mother liquor containing the hydrogen peroxide chlorination process comprises the following substances: comprises hydrochloric acid with mass concentration of 16-20%, hydrogen peroxide with mass concentration of 0.01-0.03%, and water and indispensable impurities in the rest;
more specifically, the mother liquor containing hydrogen peroxide chlorination process refers to liquid obtained after separating solids containing 6-chloro-2, 4-dinitroaniline in the process of producing 6-chloro-2, 4-dinitroaniline by using 2, 4-dinitroaniline and a hydrogen peroxide chlorination process;
step B3 sodium chlorate preparation procedure: preparing a certain amount of sodium chlorate and water into a sodium chlorate solution with the concentration of 23-27.5% and complete dissolution; preferably, the temperature of the dissolving and adding process is controlled below 30 ℃;
step B4 sodium chlorate addition procedure: gradually adding a sodium chlorate solution into a reaction kettle, and controlling the temperature to be 40-70 ℃ in the adding process; finally, controlling the molar ratio of the 2, 4-dinitroaniline to the sodium chlorate to be 1: 2.2-3; preferably, the adding process of the sodium chlorate solution in the sodium chlorate adding procedure is controlled to be 3-6 hours;
step B5 heat preservation reaction process: after the sodium chlorate is dripped, carrying out heat preservation reaction at the temperature of 45-70 ℃ for 1-2 hours, and finishing the technical heat preservation; or the reaction end point is the content of the 6-chloro-2, 4-dinitroaniline in the solid after the separation and drying of the reaction mixture is higher than 96 percent, and the heat preservation process is finished; keeping the stirring state in the heat preservation process;
preferably, in the step B5, in the heat-preservation reaction process, the reaction end point control time is the reaction end point, namely the content of 6-chloro-2, 4-dinitroaniline in the solid obtained by sampling, centrifuging and drying the reaction mixture is higher than 98%; the test method is a liquid chromatography normalization method;
preferably, in the step B5 heat preservation reaction procedure, the temperature is controlled to be 65 +/-5 ℃ in the heat preservation process;
step B6 separation process: after the reaction is finished, performing a separation process, and performing filtration or centrifugal separation to obtain a salt-containing separation liquid and a filter cake;
step B7: a drying procedure: the filter cake is dried to obtain the product 6-chloro-2, 4-dinitroaniline. After centrifugation, the salt-containing separation liquid is filtered by a filter tank and then enters a recovery tank for use in the reaction process for preparing 6-bromo-2, 4-dinitroaniline.
The mother liquor containing hydrogen peroxide chlorination process specifically refers to mother liquor obtained by oxidizing 2, 4-dinitroaniline in hydrochloric acid into chlorine by using the oxidability of hydrogen peroxide under a certain acidity condition, producing 6-chloro-2, 4-dinitroaniline from the generated chlorine and 2, 4-dinitroaniline, and separating 6-chloro-2, 4-dinitroaniline.
The mother liquor of the chlorination process containing hydrogen peroxide, which is added in the step B2, is prepared by taking 2, 4-dinitroaniline, hydrogen peroxide and hydrochloric acid as raw materials, preparing 6-chloro-2, 4-dinitroaniline by a hydrogen peroxide chlorination process, centrifuging the reacted mother liquor to generate mother liquor, filtering the mother liquor, and recycling 40-50% of the mother liquor of the chlorination process containing hydrogen peroxide in the hydrogen peroxide chlorination process, wherein the rest 50-60% of the mother liquor can be directly used for producing 6-chloro-2, 4-dinitroaniline products by the sodium chlorate process.
The salt-containing separation liquid in the step B6 is mother liquid generated by producing 6-chloro-2, 4-dinitroaniline by adopting a sodium chlorate process, and the salt-containing separation liquid contains sodium chloride.
The principle of producing 6-chloro-2, 4-dinitroaniline by recycling mother liquor is as follows:
6-chloro-2, 4-dinitroaniline is produced by a hydrogen peroxide method, the concentration of hydrochloric acid generated by the hydrogen peroxide chlorination process mother liquor containing 16% -27% of hydrogen peroxide is 40% -50% of the hydrochloric acid, and the hydrochloric acid still containing 50% -60% of the hydrochloric acid cannot be recycled, so that the direct treatment cost is high. The acidity of hydrochloric acid required for producing 6-chloro-2, 4-dinitroaniline by a sodium chlorate method is low, but sodium chloride is generated in the reaction process, and the recycling frequency of the centrifuged salt-containing separation liquid after reaction is limited.
More specifically, the mother liquor of the chlorination process containing hydrogen peroxide refers to the mother liquor of the chlorination process containing hydrogen peroxide obtained by the following steps:
an environment-friendly production process of 6-chloro-2, 4-dinitroaniline comprises the following steps:
step A1: a grinding procedure: grinding 100 parts by mass of 2, 4-dinitroaniline by a colloid mill, and adding the ground 2, 4-dinitroaniline into a reaction kettle;
step A2: a hydrochloric acid adding procedure: adding hydrochloric acid and water into a reaction kettle, raising the temperature to 45-70 ℃, and stirring for 1-2 hours under heat preservation; wherein, the amount of the added hydrochloric acid is calculated by the contained HCl, the amount ratio of the 2, 4-dinitroaniline to the HCl substance is 2, 4-dinitroaniline: HCl = 1: (4-9); the amount of the added water comprises the amount of water contained in the hydrochloric acid, so that the concentration of the hydrochloric acid is 20% -30%; more specifically, the requirements for the rate of temperature rise are: after all hydrochloric acid and water are added, the temperature is raised to 45-70 ℃ within 30-60 minutes.
More specifically, the concentration of the hydrochloric acid is 20-30%, and the mass part of the HCl is 20-30 parts calculated by taking the total mass of the water and the HCl as 100 parts.
More specifically, the temperature in the hydrochloric acid addition step was controlled to 65 ℃. + -. 5 ℃.
Step A3: adding hydrogen peroxide: dropwise adding or slowly adding hydrogen peroxide into the reaction kettle by using a metering pump, wherein the temperature is controlled to be 50-70 ℃ in the adding process; keeping the stirring state in the adding process;
wherein the mass concentration of the added hydrogen peroxide is 23-27.5%, and the 2, 4-dinitroaniline and H are2O2The mass ratio of the substances is 2, 4-dinitroaniline: h2O2=1:（1.2~3）；
More specifically, the time of adding hydrogen peroxide in the step A3 is 3-6 hours;
step A4: a heat preservation procedure: after the dropwise addition of the hydrogen peroxide is finished, preserving the heat at the temperature of 50-70 ℃ for 1-2.5 hours, and finishing the heat preservation process; or the reaction end point is the content of the 6-chloro-2, 4-dinitroaniline in the solid after the separation and drying of the reaction mixture is higher than 98 percent, and the heat preservation process is finished; keeping the stirring state in the heat preservation process;
step A5: a separation process: after the heat preservation is finished, separating the reaction mixture to obtain a filter cake and chlorination process mother liquor containing hydrogen peroxide;
more specifically, after the heat preservation process of the step A4 is finished, the separation process is directly carried out; no cooling is required.
Step A6: after separation, the filter cake is dried to obtain the product 6-chloro-2, 4-dinitroaniline.
Preferably, the separated chlorination process mother liquor containing hydrogen peroxide can be recycled.
Preferably, the purity of the 2, 4-dinitroaniline obtained in step A1 is more than 99.85 percent
Preferably, the temperature of the hydrogen peroxide solution in the step A3 is controlled below 30 ℃.
Preferably, the temperature in the step A4 is controlled at 65 +/-5 ℃, and the temperature is kept for 1-2 hours. More preferably, the reaction time is the end point of the reaction when the content of 6-chloro-2, 4-dinitroaniline after sampling and centrifugal separation is higher than 98%.
Preferably, the mother liquor of the chlorination process containing hydrogen peroxide obtained in the step A6 is sent into a recovery tank after absorbing hydrogen chloride, and is recycled.
Concentrations not mentioned in this patent document are mass concentrations.
By adopting the technical scheme, the invention has the following beneficial effects:
the 6-chloro-2, 4-dinitroaniline mother liquor recycling method utilizes the mother liquor of the hydrogen peroxide chlorination process as a raw material, and achieves the purposes of environmental protection, energy conservation and cost reduction.
Detailed Description
The patent is further illustrated below with reference to examples. The scope of protection of the patent is not limited to the specific embodiments.
Example 1
350 g of 2, 4-dinitroaniline ground by a colloid mill, 975 g of hydrogen peroxide-containing chlorination process mother liquor containing 16.36 mass percent of hydrogen chloride and 0.01 mass percent of hydrogen peroxide, 225 g of water are added into a reaction kettle, the temperature is increased to 65 ℃, stirring is carried out for 2 hours, and then the temperature is reduced to 45 ℃ for standby.
Dropwise adding 1650 g of 27% sodium chlorate solution at the speed of 200 ml per hour, controlling the temperature at 69 +/-4 ℃, after the dropwise adding is finished, carrying out heat preservation reaction for 2 hours, carrying out suction filtration to obtain 460 g of wet product, drying to obtain 416 g of product with the HPLC content of 98.3%, wherein the product yield is 98.2%, the filtrate is salt-containing separation liquid, and the salt-containing separation liquid is filtered and then sent to a recovery tank for producing 6-bromo-2, 4-dinitroaniline.
Example 2
350 g of 2, 4-dinitroaniline with the content of 99.86 percent after being ground by a colloid mill, 975 g of mother liquor of a mother liquor hydrogen peroxide chlorination process with the mass concentration of hydrogen chloride of 16.34 percent and the mass concentration of hydrogen peroxide of 0.01 percent and 225 g of water are added into a reaction kettle, the temperature is raised to 65 ℃, the stirring is carried out for 2 hours, and then the temperature is lowered to 45 ℃ for standby.
And (2) dropwise adding 1650 g of 27% sodium chlorate solution at the speed of 200 ml per hour, controlling the temperature at 69 +/-4 ℃, after the dropwise adding is finished, carrying out heat preservation reaction for 1.5 hours, carrying out suction filtration and drying to obtain 420 g of a product with the HPLC content of 98.2%, wherein the product yield is 98.3%, the filtrate is a salt-containing separation solution, and the salt-containing separation solution is filtered and then sent to a recovery tank and can be used for producing 6-bromo-2, 4-dinitroaniline.
Claims (8)
1. A6-chloro-2, 4-dinitroaniline mother liquor recycling method is characterized by comprising the following steps: the method comprises the following steps:
step B1 grinding process: grinding 2, 4-dinitroaniline by a colloid mill, and adding the ground 2, 4-dinitroaniline into a reaction kettle;
step B2, adding mother liquor of a chlorination process containing hydrogen peroxide: adding a chlorination process mother liquor containing hydrogen peroxide and a certain amount of water into a reaction kettle to ensure that the mass concentration of hydrochloric acid is 13-15%; and controlling the amount ratio of the 2, 4-dinitroaniline to the HCl substance to be 2, 4-dinitroaniline: HCl = 1: (4-9);
the mother liquor containing the hydrogen peroxide chlorination process comprises the following substances: comprises hydrochloric acid with mass concentration of 16-20%, hydrogen peroxide with mass concentration of 0.01-0.03%, and water and indispensable impurities in the rest;
step B3 sodium chlorate preparation procedure: preparing a certain amount of sodium chlorate and water into a sodium chlorate solution with the concentration of 23-27.5% and complete dissolution;
step B4 sodium chlorate addition procedure: gradually adding a sodium chlorate solution into a reaction kettle, and controlling the temperature to be 40-70 ℃ in the adding process; finally, controlling the molar ratio of the 2, 4-dinitroaniline to the sodium chlorate to be 1: 2.2-3;
step B5 heat preservation reaction process: after the sodium chlorate is dripped, carrying out heat preservation reaction at 45-70 ℃ for 1-2 hours, and finishing the heat preservation reaction; or the reaction end point is the content of the 6-chloro-2, 4-dinitroaniline in the solid after the separation and drying of the reaction mixture is higher than 96 percent, and the heat preservation process is finished; keeping the stirring state in the heat preservation process;
step B6 separation process: after the reaction is finished, performing a separation process, and performing filtration or centrifugal separation to obtain a salt-containing separation liquid and a filter cake;
step B7: a drying procedure: the filter cake is dried to obtain the product 6-chloro-2, 4-dinitroaniline.
2. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 1, which comprises the steps of: and B4, controlling the adding time in the sodium chlorate adding procedure in the step B to be 3-6 hours.
3. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 1, which comprises the steps of: in the step B5 heat preservation reaction procedure, the temperature is controlled to be 65 +/-5 ℃ in the heat preservation process.
4. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 1, which comprises the steps of: the mother liquor containing hydrogen peroxide chlorination process specifically refers to mother liquor obtained after oxidizing 2, 4-dinitroaniline in hydrochloric acid into chlorine by using the oxidability of hydrogen peroxide under a certain acidity condition, producing 6-chloro-2, 4-dinitroaniline from the generated chlorine and 2, 4-dinitroaniline, and separating 6-chloro-2, 4-dinitroaniline; the mother liquor of the hydrogen peroxide chlorination process comprises hydrochloric acid, water, dissolved 2, 4-dinitroaniline and 6-chloro-2, 4-dinitroaniline as well as inevitable process impurities.
5. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 1, which comprises the steps of: the hydrogen peroxide chlorination process mother liquor refers to hydrogen peroxide chlorination process mother liquor obtained by the following process steps:
step A1: a grinding procedure: grinding 100 parts by mass of 2, 4-dinitroaniline by a colloid mill, and adding the ground 2, 4-dinitroaniline into a reaction kettle;
step A2: a hydrochloric acid adding procedure: adding hydrochloric acid and water into a reaction kettle, raising the temperature to 45-70 ℃, and stirring for 1-2 hours under heat preservation; wherein, the amount of the added hydrochloric acid is calculated by the contained HCl, the amount ratio of the 2, 4-dinitroaniline to the HCl substance is 2, 4-dinitroaniline: HCl = 1: (4-9); the amount of the added water comprises the amount of water contained in the hydrochloric acid, so that the concentration of the hydrochloric acid is 20% -30%;
step A3: adding hydrogen peroxide: dropwise adding or slowly adding hydrogen peroxide into the reaction kettle by using a metering pump, wherein the temperature is controlled to be 50-70 ℃ in the adding process; keeping the stirring state in the adding process;
wherein the mass concentration of the added hydrogen peroxide is 23-27.5%, and the 2, 4-dinitroaniline and H are2O2The mass ratio of the substances is 2, 4-dinitroaniline: h2O2=1:（1.2~3）；
Step A4: a heat preservation procedure: after the dropwise addition of the hydrogen peroxide is finished, preserving the heat at the temperature of 50-70 ℃ for 1-2.5 hours, and finishing the heat preservation process; or the reaction end point is the content of the 6-chloro-2, 4-dinitroaniline in the separated and dried solid is higher than 98 percent, and the heat preservation process is finished; keeping the stirring state in the heat preservation process;
step A5: a separation process: after the heat preservation is finished, separating the reaction mixture to obtain a filter cake and chlorination process mother liquor containing hydrogen peroxide;
step A6: after separation, the filter cake is dried to obtain the product 6-chloro-2, 4-dinitroaniline.
6. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 5, wherein the method comprises the following steps: the step A4 is directly carried out in the separation process after the heat preservation process is finished; no cooling is required.
7. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 5, wherein the method comprises the following steps: and the time of the hydrogen peroxide adding process in the step A3 is 3-6 hours.
8. The method for recycling the mother liquor of 6-chloro-2, 4-dinitroaniline according to claim 5, wherein the method comprises the following steps: and D, absorbing hydrogen chloride in the chlorination process mother liquor containing hydrogen peroxide obtained in the step A6, and then sending the chlorination process mother liquor into a recovery tank for recycling.
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Application publication date: 20200410 |