CN110746347A - Method for recovering and recycling tetrachloropyridine rectification residual liquid - Google Patents
Method for recovering and recycling tetrachloropyridine rectification residual liquid Download PDFInfo
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- CN110746347A CN110746347A CN201911090019.9A CN201911090019A CN110746347A CN 110746347 A CN110746347 A CN 110746347A CN 201911090019 A CN201911090019 A CN 201911090019A CN 110746347 A CN110746347 A CN 110746347A
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- tetrachloropyridine
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/61—Halogen atoms or nitro radicals
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D213/00—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members
- C07D213/02—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members
- C07D213/04—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom
- C07D213/60—Heterocyclic compounds containing six-membered rings, not condensed with other rings, with one nitrogen atom as the only ring hetero atom and three or more double bonds between ring members or between ring members and non-ring members having three double bonds between ring members or between ring members and non-ring members having no bond between the ring nitrogen atom and a non-ring member or having only hydrogen or carbon atoms directly attached to the ring nitrogen atom with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D213/62—Oxygen or sulfur atoms
- C07D213/70—Sulfur atoms
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Abstract
The invention provides a method for recovering and recycling tetrachloropyridine rectification residual liquid, which is a method for soaking tetrachloropyridine rectification residual liquid by using an alcohol solvent to remove tar, distilling by using water vapor to extract pentachloropyridine and dehydrating and purifying by using an inert solvent. The pentachloropyridine purified by the method can be added into a reaction kettle together with sodium sulfide, and the 2,3,5, 6-tetrachloro-4-pyridinethiol can be obtained by heat filtration and acidification after the heat preservation reaction. The method is simple to operate, high-purity pentachloropyridine can be obtained from the waste tetrachloropyridine rectification residual liquid, and the pentachloropyridine can also be used for synthesizing 2,3,5, 6-tetrachloro-4-pyridinethiol, so that industrialization is easy to realize.
Description
Technical Field
The invention belongs to the technical field of resources and environment, relates to the field of waste liquid treatment, and particularly relates to recovery and reuse of tetrachloropyridine rectification residual liquid.
Background
The residual liquid of the tetrachloropyridine rectification is the residual material in a kettle after the pyridine and chlorine are used for high-temperature catalytic chlorination in the existing tetrachloropyridine production process, reaction gas is condensed and collected in a collection kettle, and then the material in the collection kettle is transferred to a rectification kettle for rectification and purification. In the existing production process, the distillation residual liquid of the distillation kettle accounts for 5-10% of the distillation residual liquid of the tetrachloropyridine, and the distillation residual liquid accounts for a relatively large proportion. In the past, the tetrachloropyridine rectification residual liquid is treated in a dangerous waste mode, so that the production cost and the environmental protection pressure are greatly increased. At present, no better treatment method is reported.
2,3,5, 6-tetrachloro-4-pyridinethiol is an important pyridine pesticide intermediate, is mainly applied to the preparation of 2,3,5, 6-tetrachloro-4-methylsulfonylpyridine, is used for preventing mildew from invading crops, and is widely applied to the fields of printing ink, papermaking, textiles, polymer materials and the like. If the tetrachloropyridine rectification residual liquid can be recycled and reprocessed for preparing 2,3,5, 6-tetrachloro-4-pyridinethiol, the method is a resource utilization of waste.
Disclosure of Invention
The invention aims to provide a method for recovering and recycling tetrachloropyridine rectification raffinate. The raw material of the method is derived from the rectification residual liquid, the high-purity product pentachloropyridine can be directly obtained by recycling the pentachloropyridine, and further, the high-purity 2,3,5, 6-tetrachloro-4-pyridinethiol can be prepared.
The invention is realized by the following technical scheme:
a method for recovering and reusing tetrachloropyridine rectification raffinate comprises the following steps:
a) uniformly stirring tetrachloropyridine rectification residual liquid and an alcohol solvent at 50-60 ℃, cooling to below 30 ℃, and filtering; the mass ratio of the tetrachloropyridine rectification residual liquid to the alcohol solvent is 1: (0.5 to 2.0); the tetrachloropyridine rectification residual liquid is a residual liquid generated by rectification separation of tetrachloropyridine and pentachloropyridine which are pyridine chlorination products, wherein the content of pentachloropyridine is 40-50%, the content of tetrachloropyridine is 2-5%, the content of pyridine tar is 30-40%, and the content of carbide is 5-20%;
b) crushing the filter cake obtained by filtering in the step a), adding water, introducing steam for distillation, and taking out the active ingredient pentachloropyridine in the filter cake by using the steam to obtain a pentachloropyridine water mixture;
c) filtering the pentachloropyridine water mixture obtained in the step b), mixing a filter cake with an inert solvent, distilling to remove the inert solvent, water and residual trace impurities, and cooling residual liquid to obtain a pentachloropyridine product.
The preferable pentachloropyridine product reacts with sodium sulfide in an aqueous phase, and 2,3,5, 6-tetrachloro-4-pyridinethiol can be obtained after filtration and acidification.
The method for preparing 2,3,5, 6-tetrachloro-4-pyridinethiol from tetrachloropyridine rectification raffinate comprises the following specific steps:
preferred alcoholic solvents in step b) include methanol, ethanol, isopropanol and tert-butanol;
the preferable mass ratio of the rectification residual liquid to the alcohol solvent in the step b) is 1: (1-1.5);
preferably, the mass ratio of the filter cake to water in the step c) is 1: (1-3);
preferably, the inert solvent in step d) comprises carbon tetrachloride, toluene, chlorobenzene, xylene;
preferably, the mass ratio of the pentachloropyridine to the inert solvent in the step d) is 1: (0.3-0.6).
Preferably, the purity of the pentachloropyridine product in step d) is > 97%.
Preferably, the pentachloropyridine and the sodium sulfide are refluxed in a mixture of water and tetrahydrofuran for 4-8 hours, then filtered at 50-60 ℃, the filtrate is acidified by adding hydrochloric acid, and then filtered to obtain 2,3,5, 6-tetrachloro-4-pyridinethiol.
The method comprises the steps of soaking tetrachloropyridine rectification residual liquid in an alcohol solvent to remove tar, distilling with water vapor to extract pentachloropyridine, and dehydrating and purifying with an inert solvent. The pentachloropyridine purified by the method can be added into a reaction kettle with sodium sulfide according to a certain proportion, and the 2,3,5, 6-tetrachloro-4-pyridinethiol pure product can be obtained by heat filtration and acidification after the heat preservation reaction. The method is simple to operate, high-purity pentachloropyridine can be obtained from the waste tetrachloropyridine rectification residual liquid, and the pentachloropyridine can also be used for synthesizing 2,3,5, 6-tetrachloro-4-pyridinethiol, so that industrialization is easy to realize.
Compared with the prior art, the invention has the advantages that:
1. the raw material of the method is the rectification raffinate from the tetrachloropyridine rectification section, thereby realizing the reutilization of waste, and reducing the environmental protection expenditure and the environmental protection pressure.
2. The purity of the product pentachloropyridine obtained by the method is more than 97%, and the purity of the finished 2,3,5, 6-tetrachloro-4-pyridinethiol product reaches more than 98%, and considerable economic benefit can be brought.
3. The invention has the advantages of low cost, safety, no pollution and easy separation of products by taking part of the solvent as water and water as a medium for separation and purification.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
Stirring 100 g of the rectification residual liquid and 100 g of ethanol at 50-60 ℃, cooling to below 30 ℃, and filtering. Adding 100 g of the filter cake into 200 g of water, introducing steam for steam distillation, filtering collected fractions, adding 50 g of dimethylbenzene into 100 g of the crushed filter cake, then carrying out water separation and impurity removal, and distilling dimethylbenzene in a system after water separation is finished to obtain 41 g of white pentachloropyridine pure product with the HPLC content of 98.34%. 40 g of pentachloropyridine and 12 g of sodium sulfide are taken to be refluxed for 5 hours in a mixture of water and tetrahydrofuran (the volume ratio is 1: 1), then the mixture is filtered at 55 ℃, hydrochloric acid is added into the filtrate for acidification, and then the filtrate is filtered by suction to obtain 31.5 g of 2,3,5, 6-tetrachloro 4-pyridinethiol with the content of 98.03 percent and the yield of 82.23 percent.
Example 2
The procedure is as in example 1, except that the amount of ethanol added is 150 g, the product pentachloropyridine is 46 g, and the HPLC content is 98.27%. The subsequent production of 31.6 g of 2,3,5, 6-tetrachloro 4-pyridinethiol with a content of 98.77% and a yield of 82.49%.
Example 3
The procedure is as in example 1, except that toluene is used as the inert solvent, 43 g of product is obtained, and the HPLC content is 97.43%. The procedure is as in example 1 except that the amount of pentachloropyridine added is increased to 43 g, 33.2 g of 2,3,5, 6-tetrachloro 4-pyridinethiol is produced, the content is 99.01%, and the yield is 86.67%.
Example 4
The procedure is as in example 1, except that the alcoholic solvent is isopropanol 100 g, the amount of product 45 g, and the HPLC content 98.37%. 32.4 g of 2,3,5, 6-tetrachloro-4-pyridinethiol is subsequently produced, the content is 98.65 percent, and the yield is 82.58 percent.
Example 5
The procedure is as in example 1, except that the amount of xylene added is 80 g, the product pentachloropyridine is 45 g, and the HPLC content is 99.26%. The subsequent product, 34.7 g, 99.27% in content and 90.58% in yield, was 2,3,5, 6-tetrachloro 4-pyridinethiol.
Claims (8)
1. A method for recovering and recycling tetrachloropyridine rectification residual liquid is characterized by comprising the following steps:
a) uniformly stirring tetrachloropyridine rectification residual liquid and an alcohol solvent at 50-60 ℃, cooling to below 30 ℃, and filtering; the mass ratio of the tetrachloropyridine rectification residual liquid to the alcohol solvent is 1: (0.5 to 2.0); the tetrachloropyridine rectification residual liquid is a residual liquid generated by rectification separation of tetrachloropyridine and pentachloropyridine which are pyridine chlorination products, wherein the content of pentachloropyridine is 40-50%, the content of tetrachloropyridine is 2-5%, the content of pyridine tar is 30-40%, and the content of carbide is 5-20%;
b) crushing the filter cake obtained by filtering in the step a), adding water, introducing steam for distillation, and taking out the active ingredient pentachloropyridine in the filter cake by using the steam to obtain a pentachloropyridine water mixture;
c) filtering the pentachloropyridine water mixture obtained in the step b), mixing a filter cake with an inert solvent, distilling to remove the inert solvent, water and residual trace impurities, and cooling residual liquid to obtain a pentachloropyridine product.
2. The method for recovering and reusing tetrachloropyridine rectification raffinate according to claim 1, wherein 2,3,5, 6-tetrachloro-4-pyridinethiol can be obtained by reacting pentachloropyridine product with sodium sulfide in water or organic phase, filtering and acidifying.
3. The method for recovering and reusing tetrachloropyridine rectification raffinate according to claim 1 or 2, characterized in that the alcohol solvent in step a) comprises one or more of methanol, ethanol, isopropanol and tert-butanol.
4. The method for recovering and reusing tetrachloropyridine rectification raffinate according to claim 1 or 2, characterized in that the mass ratio of the rectification raffinate to the alcohol solvent in step a) is 1: (1-1.5).
5. The method for recovering and reusing a tetrachloropyridine rectification residue according to claim 1 or 2, wherein the mass ratio of the filter cake to water in the step b) is 1: (1-3).
6. The method for recovering and reusing tetrachloropyridine rectification residue according to claim 1 or 2, wherein the inert solvent in step c) comprises one or more of carbon tetrachloride, toluene, chlorobenzene and xylene.
7. The method for recovering and reusing tetrachloropyridine rectification raffinate according to claim 1 or 2, characterized in that the mass ratio of pentachloropyridine to inert solvent in step c) is 1: (0.3-0.6).
8. The method for recovering and recycling the residual liquid of tetrachloropyridine rectification according to claim 1 or 2, wherein pentachloropyridine and sodium sulfide are refluxed in a mixture of water and tetrahydrofuran for 4-8 hours, then filtered at 50-60 ℃, and the filtrate is acidified by adding hydrochloric acid and then filtered by suction filtration to obtain 2,3,5, 6-tetrachloro 4-pyridinethiol.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4225718A (en) * | 1979-02-22 | 1980-09-30 | The Dow Chemical Company | Process for recovering 2,3,5,6-tetrachloropyridine |
| US4515953A (en) * | 1983-04-22 | 1985-05-07 | Kalama Chemical, Inc. | Production of polychlorinated pyridine mixtures by liquid phase chlorination of pyridine or pyridine hydrochloride |
| CN101768107A (en) * | 2010-01-13 | 2010-07-07 | 北京颖泰嘉和科技股份有限公司 | Method for preparing polychlorinated pyridine |
| CN102351785A (en) * | 2011-08-11 | 2012-02-15 | 江苏九九久科技股份有限公司 | Method for preparing 3, 5, 6-trichloropyridin-2-ol sodium |
| CN105085381A (en) * | 2014-05-12 | 2015-11-25 | 利尔化学股份有限公司 | Method for separating chloropyridine mixture |
-
2019
- 2019-11-08 CN CN201911090019.9A patent/CN110746347B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4225718A (en) * | 1979-02-22 | 1980-09-30 | The Dow Chemical Company | Process for recovering 2,3,5,6-tetrachloropyridine |
| US4515953A (en) * | 1983-04-22 | 1985-05-07 | Kalama Chemical, Inc. | Production of polychlorinated pyridine mixtures by liquid phase chlorination of pyridine or pyridine hydrochloride |
| CN101768107A (en) * | 2010-01-13 | 2010-07-07 | 北京颖泰嘉和科技股份有限公司 | Method for preparing polychlorinated pyridine |
| CN102351785A (en) * | 2011-08-11 | 2012-02-15 | 江苏九九久科技股份有限公司 | Method for preparing 3, 5, 6-trichloropyridin-2-ol sodium |
| CN105085381A (en) * | 2014-05-12 | 2015-11-25 | 利尔化学股份有限公司 | Method for separating chloropyridine mixture |
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