CN112142603A - Preparation method of 2, 4, 6-trichloroaniline - Google Patents
Preparation method of 2, 4, 6-trichloroaniline Download PDFInfo
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- CN112142603A CN112142603A CN201910558175.7A CN201910558175A CN112142603A CN 112142603 A CN112142603 A CN 112142603A CN 201910558175 A CN201910558175 A CN 201910558175A CN 112142603 A CN112142603 A CN 112142603A
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- C07C209/00—Preparation of compounds containing amino groups bound to a carbon skeleton
- C07C209/04—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups
- C07C209/06—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of halogen atoms
- C07C209/10—Preparation of compounds containing amino groups bound to a carbon skeleton by substitution of functional groups by amino groups by substitution of halogen atoms with formation of amino groups bound to carbon atoms of six-membered aromatic rings or from amines having nitrogen atoms bound to carbon atoms of six-membered aromatic rings
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Abstract
The invention provides a preparation method of 2, 4, 6-trichloroaniline, which comprises the following steps: adding aniline into a glacial acetic acid/alcohol/halogenated benzene mixed solvent, and stirring to control the temperature; step two, introducing excessive dry hydrogen chloride gas while stirring; step three, introducing excessive chlorine gas under stirring; step four, controlling the temperature to be less than or equal to 25 ℃ in the whole reaction process until the reaction in the step is finished; step five, slowly heating to 55 ℃ or lower, removing excessive hydrogen chloride gas and chlorine gas until no obvious gas is generated, and then stirring and cooling to room temperature; and sixthly, filtering, recovering and mechanically using the obtained filtrate, namely the glacial acetic acid/alcohol/halogenated benzene mixed solvent, repeatedly rinsing the obtained solid with water, and then drying to obtain the 2, 4, 6-trichloroaniline white solid with the product purity of more than 98%.
Description
Technical Field
The invention relates to the field of organic chemical synthesis, in particular to a preparation method of 2, 4, 6-trichloroaniline.
Background
2, 4, 6-trichloroaniline is an important chemical raw material and is widely applied to the production of products such as azo dyes, insecticides, bactericides, herbicides and the like. The 2, 4, 6-trichloroaniline is white or slightly yellow needle-shaped crystal, is dissolved in organic solvents such as alcohol, ether, carbon disulfide, petroleum ether and the like, is insoluble in water, and slightly sublimes at high temperature. The industrial production adopts aniline as raw material, and prepares 2, 4, 6-trichloroaniline by a chlorine chlorination route, because amino is a strong activated group, chlorination is positioned at ortho-position and para-position, namely 2, 4 and 6 positions, the reaction is easy to carry out, and aniline is cheap and easy to obtain. There are also known methods for synthesizing 2, 4, 6-trichloroaniline from other raw materials such as various aminobenzoic acids (CN 10357556B), but these raw materials are expensive in terms of cost and are not suitable for industrial production.
The research on aniline chlorination mainly focuses on solvent systems, reaction temperature, material ratio and technical processes. Water is adopted as a solvent at first, and the method has the advantages of cheap and easily available water and little pollution, but free amino is easily oxidized by chlorine in the reaction, so that reaction materials are blackened, byproducts are more, the yield is low, the product quality is poor, and the method is eliminated. At present, trichloroaniline is prepared by adopting an organic solvent system, such as chloroform, dichloroethane, chlorobenzene, glacial acetic acid, benzene and glacial acetic acid, carbon tetrachloride and methanol and the like, wherein the carbon tetrachloride is used as a solvent, so that the obtained product has the best quality and the highest yield; however, with the improvement of environmental protection requirements and the deep understanding of the influence of various reagents on the environment and human bodies, many reagents are no longer suitable for use, not only carbon tetrachloride is limited in use, but also other reasons such as strong carcinogenicity of benzene, flammability, explosiveness, toxicity and the like of dichloroethane can not be basically used for actual industrial production. Domestic manufacturers mostly use acetic acid as a solvent, but the quality of products obtained by using pure acetic acid as the solvent is relatively poor, and the acetic acid has great corrosion damage to equipment and is not easy to recycle.
Disclosure of Invention
Aiming at the defects in the prior art, the quality, yield, cost, influence of the production process on the environment and human body and the like are comprehensively considered, and the technical problem to be solved by the invention is to provide the preparation method of the 2, 4, 4-trichloroaniline, wherein a glacial acetic acid/alcohol/halogenated benzene mixed solvent is used as a solvent system for reaction for the first time, so that the intermiscibility among aniline, hydrochloric acid gas, chlorine and the solvent is improved, the salt formation of the aniline is easier, the reaction image forward and reverse reaction directions are promoted to be carried out, the occurrence of side reactions is reduced, and the yield is improved; the operations such as water washing and the like are avoided, and the generation of three wastes is reduced; the recovered mother liquor is obtained after filtration, and can be directly used without extra step treatment; the whole process is simple, convenient to operate, high in yield, low in cost and convenient for industrial production.
According to one aspect of the present invention, there is provided a process for the preparation of 2, 4, 4-trichloroaniline, comprising the steps of:
adding aniline into a glacial acetic acid/alcohol/halogenated benzene mixed solvent, and stirring and controlling the temperature to be less than or equal to 25 ℃;
secondly, introducing excessive dry hydrogen chloride gas under stirring, wherein the temperature is controlled to be 25 ℃ or below in the process;
step three, introducing excessive chlorine gas under stirring;
step four, controlling the temperature to be less than or equal to 25 ℃ in the whole reaction process; ending the reaction in the above steps;
step five, slowly heating to the temperature of less than or equal to 55 ℃, and removing excessive hydrogen chloride gas and chlorine gas; until no obvious gas is generated, then stirring and cooling to room temperature;
filtering, and recycling the obtained filtrate, namely the glacial acetic acid/alcohol/halogenated benzene mixed solvent for reuse; the obtained solid is repeatedly rinsed by water and then dried, and the white solid of the 2, 4, 6-trichloroaniline is obtained. The product purity is more than 98 percent (high performance liquid chromatography), and the yield is more than 88 percent.
The alcohol used in step one is methanol, ethanol, propanol, butanol, isopropanol or their mixture, etc., wherein preferred is propanol and isopropanol or their mixture. The halogenated benzene used is chlorobenzene, fluorobenzene or a mixture thereof, of which chlorobenzene is preferred. The volume ratio of the glacial acetic acid to the alcohol is glacial acetic acid: alcohol 15: 1 to 25: 1, wherein 20: 1. the volume ratio of the glacial acetic acid to the halogenated benzene is glacial acetic acid: halogenated benzene ═ 15: 1 to 25: 1, wherein 20: 1.
in the second step and the third step, namely in the process of introducing the hydrogen chloride and the chlorine, the temperature of the system is controlled to be less than or equal to 25 ℃. Introducing hydrogen chloride gas as dry hydrogen chloride gas; the gas amount and aniline molar ratio are introduced as follows: hydrogen chloride ═ 1: 1.2 to 1: 2.2, among them, preferred is 1: 1.6. the amount of chlorine gas introduced and the molar ratio of aniline are as follows: chlorine gas 1: 1.1 to 1: 1.5, among which 1: 1.2.
in the fifth step, the temperature rise is controlled within the range of 45 ℃ to 55 ℃, wherein the temperature rise is preferably 50 ℃. The stirring constant temperature is ended until no gas is generated, namely, the alkaline solution absorbing gas at the tail end begins to suck back slightly.
And sixthly, filtering the obtained filtrate, namely repeatedly recycling the glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of hydrogen chloride and chlorine and the product. The solid obtained by filtration was repeatedly rinsed with water.
Compared with the prior art, the invention has the following beneficial effects: the glacial acetic acid/alcohol/halogenated benzene mixed solvent is used as a solvent system for the reaction for the first time, no toxic or harmful solvent is used, the system can improve the intermiscibility among aniline, hydrochloric acid gas, chlorine and the solvent, so that the aniline can be salified more easily, the reaction is carried out in the positive and negative reaction direction, the occurrence of side reactions is reduced, and the yield is improved; the operations such as water washing and the like are avoided, and the generation of three wastes is reduced; the recovered mother liquor is obtained after filtration, and can be directly used without extra step treatment; especially, the chlorobenzene, the isopropanol and the like with higher boiling points are selected preferably, the loss is lower in the process of heating to expel residual hydrogen chloride and chlorine in the solution, the use amount and the cost of materials are reduced, and the generation of three wastes is reduced. The whole process is simple, convenient to operate, high in yield, low in cost and convenient for industrial production. The total yield can reach more than 88 percent; the purity of the product can reach more than 98 percent after rinsing and drying, and no additional purification is needed.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Example 1:
in a 1000 ml four-neck flask with stirring, 400 ml of glacial acetic acid, 20 ml of anhydrous methanol, 20 ml of chlorobenzene and 50 g (0.537 mol) of aniline as raw materials are added in sequence; stirring, cooling to below 25 ℃, introducing dry hydrogen chloride gas, and collecting tail gas (including air in the initial stage and completely hydrogen chloride gas after air is exhausted) by using pure water; introducing the mixture for about 2 hours at the rate of 150 ml/min, wherein 19.6 g of hydrogen chloride gas is theoretically needed; 29.2 g of gas was actually introduced, and the introduction of hydrogen chloride gas was stopped.
Keeping stirring at the temperature of below 25 ℃, introducing chlorine gas into the reaction system with the completion of the acidification of the salt at the speed of 70 ml/min, and collecting tail gas by using pure water (the tail gas contains a large amount of hydrogen chloride gas and part of chlorine gas). This step is an exothermic reaction, and the rate of temperature reduction (ice-water bath) needs to be noted during the reaction. The theoretical amount of chlorine is 114.4 g; 130 g of actual reaction is introduced; after 10 hours, the reaction was complete.
Slowly raising the temperature to 50 ℃ under stirring, removing a large amount of gas from the system, and absorbing the gas by using a saturated sodium bicarbonate solution. After a small test, substantially no gas was produced again, the reaction was terminated, and cooling to room temperature with stirring resulted in the formation of a large amount of white precipitate.
Filtering, separating out precipitate and mother liquor, and obtaining solid which is a crude product; the filtrate is glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of crude product, chlorine and hydrogen chloride, and the mother liquor is recycled and reused. The obtained crude product is rinsed twice with 200 ml of water and dried to obtain the target product 2, 4, 4-trichloroaniline, the yield is 89.2 percent, and the HPLC purity is 98.3 percent.
Example 2:
in a 1000 ml four-neck flask with stirring, 400 ml of glacial acetic acid, 20 ml of anhydrous isopropanol, 20 ml of chlorobenzene and 50 g (0.537 mol) of aniline as raw material are added in sequence; stirring, cooling to below 25 ℃, introducing dry hydrogen chloride gas, and absorbing tail gas (including air in the initial stage and completely hydrogen chloride gas after air is exhausted) by using a saturated sodium bicarbonate solution; the hydrogen chloride gas was stopped after about 2.3 hours at a rate of 150 ml/min.
Keeping the temperature not more than 25 ℃, stirring, introducing chlorine gas into the reaction system which is subjected to the salt acidification at the speed of 70 ml/min, and absorbing tail gas by using a saturated sodium bicarbonate solution (the tail gas contains a large amount of hydrogen chloride gas and part of chlorine gas). This step is an exothermic reaction, and the rate of temperature reduction (ice-water bath) needs to be noted during the reaction. After 12 hours, the reaction was complete.
Slowly raising the temperature to 55 ℃ under stirring, removing a large amount of gas from the system, and absorbing the gas by using a saturated sodium bicarbonate solution. After a small test, substantially no gas was produced again, the reaction was terminated, and cooling to room temperature with stirring resulted in the formation of a large amount of white precipitate.
Filtering, separating out precipitate and mother liquor, and obtaining solid which is a crude product; the filtrate is glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of crude product, chlorine and hydrogen chloride, and the mother liquor is recycled and reused. The obtained crude product is rinsed twice with 200 ml of water and dried to obtain the target product 2, 4, 4-trichloroaniline, the yield is 89.7 percent, and the HPLC purity is 98.2 percent.
Example 3:
in a 1000 ml four-neck flask with stirring, 320 ml of glacial acetic acid, 20 ml of anhydrous isopropanol, 20 ml of chlorobenzene and 50 g (0.537 mol) of aniline as raw material are added in sequence; stirring, cooling to below 25 ℃, introducing dry hydrogen chloride gas, and absorbing tail gas (including air in the initial stage and completely hydrogen chloride gas after air is exhausted) by saturated lime water; the hydrogen chloride gas was stopped after about 2.2 hours at a rate of 150 ml/min.
Keeping the temperature not more than 25 ℃, stirring, introducing chlorine gas at the rate of 70 ml/min into the reaction system after the salt acidification is finished, and absorbing tail gas by saturated lime water. After 11 hours, the reaction was complete.
Slowly raising the temperature to 50 ℃ under stirring, removing a large amount of gas from the system, and absorbing the gas by saturated lime water. After a small test, the reaction was terminated and cooled to room temperature with stirring, and a large amount of white precipitate was formed.
Filtering, separating out precipitate and mother liquor, and obtaining solid which is a crude product; the filtrate is glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of crude product, chlorine and hydrogen chloride, and the mother liquor is recycled and reused. The obtained crude product is rinsed twice with 200 ml of water and dried to obtain the target product 2, 4, 4-trichloroaniline with the yield of 88 percent and the HPLC purity of 98.1 percent.
Example 3:
380 ml of glacial acetic acid, 20 ml of anhydrous isopropanol, 20 ml of fluorobenzene and 50 g (0.537 mol) of aniline are added into a 1000 ml four-neck flask with stirring in sequence; stirring, cooling to below 25 ℃, introducing dry hydrogen chloride gas, and absorbing tail gas by saturated lime water; the hydrogen chloride gas was stopped after 2 hours at a rate of 150 ml/min.
Keeping the temperature not more than 25 ℃, stirring, introducing chlorine gas at the rate of 70 ml/min into the reaction system after the salt acidification is finished, and absorbing tail gas by saturated lime water. After 10 hours, the reaction was complete.
Slowly raising the temperature to 50 ℃ under stirring, removing a large amount of gas from the system, and absorbing the gas by saturated lime water. After a small test, the reaction was terminated and cooled to room temperature with stirring, and a large amount of white precipitate was formed.
Filtering, separating out precipitate and mother liquor, and obtaining solid which is a crude product; the filtrate is a glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of crude product, chlorine and hydrogen chloride, and the mother liquor is recycled (the color of the mother liquor is darker). The obtained crude product is rinsed twice with 200 ml of water and dried to obtain the target product 2, 4, 4-trichloroaniline, the yield is 88.3 percent, and the HPLC purity is 98.0 percent.
Example 4:
380 ml of glacial acetic acid, 20 ml of absolute propanol, 20 ml of chlorobenzene and 50 g (0.537 mol) of aniline are added into a 1000 ml four-neck flask with stirring in sequence; stirring, cooling to below 25 ℃, introducing dry hydrogen chloride gas, and absorbing tail gas by saturated lime water; the hydrogen chloride gas was stopped after 2 hours at a rate of 150 ml/min.
Keeping the temperature not more than 25 ℃, stirring, introducing chlorine gas at the rate of 70 ml/min into the reaction system after the salt acidification is finished, and absorbing tail gas by saturated lime water. After 10 hours, the reaction was complete.
Slowly raising the temperature to 50 ℃ under stirring, removing a large amount of gas from the system, and absorbing the gas by saturated lime water. After a small test, the reaction was terminated and cooled to room temperature with stirring, and a large amount of white precipitate was formed.
Filtering, separating out precipitate and mother liquor, and obtaining solid which is a crude product; the filtrate is a glacial acetic acid/alcohol/halogenated benzene mixed solvent containing a small amount of crude product, chlorine and hydrogen chloride, and the mother liquor is recycled (the color of the mother liquor is darker). The obtained crude product is rinsed twice with 200 ml of water and dried to obtain the target product 2, 4, 4-trichloroaniline, the yield is 88.2 percent, and the HPLC purity is 98.7 percent.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (10)
1. The preparation method of the 2, 4, 6-trichloroaniline is characterized by comprising the following steps:
adding aniline into a glacial acetic acid/alcohol/halogenated benzene mixed solvent, and stirring and controlling the temperature to be less than or equal to 25 ℃;
secondly, introducing excessive dry hydrogen chloride gas under stirring, wherein the temperature is controlled to be 25 ℃ or below in the process;
step three, introducing excessive chlorine gas under stirring;
step four, controlling the temperature to be less than or equal to 25 ℃ in the whole reaction process; ending the reaction in the above steps;
step five, slowly heating to the temperature of less than or equal to 55 ℃, and removing excessive hydrogen chloride gas and chlorine gas; until no obvious gas is generated, then stirring and cooling to room temperature;
filtering, and recycling the obtained filtrate, namely the glacial acetic acid/alcohol/halogenated benzene mixed solvent for reuse; repeatedly rinsing the obtained solid with water, and then drying to obtain 2, 4, 6-trichloroaniline white solid; the product purity is more than 98% (high performance liquid chromatography).
2. The method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein the mixed solvent in the first step is a mixed solvent of glacial acetic acid, alcohol and halogenated benzene.
3. The process for the preparation of 2, 4, 6-trichloroaniline according to claim 2, characterized in that the alcohol used is methanol, ethanol, propanol, butanol, isopropanol or a mixture of methanol, ethanol, propanol, butanol, isopropanol, preferably propanol and isopropanol or a mixture of propanol and isopropanol.
4. The process for the preparation of 2, 4, 6-trichloroaniline according to claim 2, characterized in that the halogenated benzene used is chlorobenzene, fluorobenzene or a mixture of chlorobenzene and fluorobenzene, preference being given to chlorobenzene.
5. The method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein in the first step, the volume ratio of glacial acetic acid to alcohol is glacial acetic acid: alcohol 15: 1 to 25: 1, wherein 20: 1.
6. the method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein in the first step, the volume ratio of glacial acetic acid to halogenated benzene is glacial acetic acid: halogenated benzene ═ 15: 1 to 25: 1, wherein 20: 1.
7. the method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein the temperature of the system is controlled to be less than or equal to 25 ℃ during the introduction of hydrogen chloride and chlorine.
8. The method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein in the second step, the introduced hydrogen chloride gas is dry hydrogen chloride gas; the gas amount and aniline molar ratio are introduced as follows: hydrogen chloride ═ 1: 1.2 to 1: 2.2, among them, preferred is 1: 1.6.
9. the method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein the chlorine gas amount and the aniline molar ratio in the third step are that the ratio of aniline: chlorine gas 1: 1.1 to 1: 1.5, among which 1: 1.2.
10. the method for preparing 2, 4, 6-trichloroaniline according to claim 1, wherein in the fifth step, the temperature rise is controlled within the range of 45 ℃ to 55 ℃, preferably 50 ℃; the stirring constant temperature is ended until no gas is generated, namely, the alkaline solution absorbing gas at the tail end begins to suck back slightly.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113429298A (en) * | 2021-07-12 | 2021-09-24 | 翱华工程技术股份有限公司 | Preparation method, production equipment and use method of 2,4, 6-trichloroaniline |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4447647A (en) * | 1982-01-05 | 1984-05-08 | Bayer Aktiengesellschaft | Process for the preparation of 2,4,6-trichloroaniline |
| CN103524358A (en) * | 2013-10-11 | 2014-01-22 | 浙江大学 | Synthetic method of 2, 6-dichloroaniline |
-
2019
- 2019-06-26 CN CN201910558175.7A patent/CN112142603A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4447647A (en) * | 1982-01-05 | 1984-05-08 | Bayer Aktiengesellschaft | Process for the preparation of 2,4,6-trichloroaniline |
| CN103524358A (en) * | 2013-10-11 | 2014-01-22 | 浙江大学 | Synthetic method of 2, 6-dichloroaniline |
Non-Patent Citations (3)
| Title |
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| 张宝文: "由苯胺合成2,4,6－三氯苯胺", 《沈阳化工》 * |
| 许文松 等: "新型溶剂在2,4,6-三氯苯胺制备中的应用", 《精细石油化工》 * |
| 赵春 等: "两种农药中间体的合成", 《湖北农业科学》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113429298A (en) * | 2021-07-12 | 2021-09-24 | 翱华工程技术股份有限公司 | Preparation method, production equipment and use method of 2,4, 6-trichloroaniline |
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