CN112250618A - Separation method of polychlorinated pyridine compound and heat-conducting oil mixture - Google Patents
Separation method of polychlorinated pyridine compound and heat-conducting oil mixture Download PDFInfo
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- CN112250618A CN112250618A CN202011233715.3A CN202011233715A CN112250618A CN 112250618 A CN112250618 A CN 112250618A CN 202011233715 A CN202011233715 A CN 202011233715A CN 112250618 A CN112250618 A CN 112250618A
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- polychlorinated pyridine
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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
Abstract
The invention discloses a separation method of a polychlorinated pyridine compound and a heat-conducting oil mixture, and belongs to the technical field of fine chemical engineering. The method comprises the steps of firstly cooling a mixture of a polychlorinated pyridine compound and heat conduction oil, adding a free radical absorbent and a diluent into a solid attached with the polychlorinated pyridine compound for dissolving, then adding an auxiliary agent into the solution, heating, distilling under reduced pressure to collect a fraction, and dissolving and refining the collected fraction and a polar solvent to obtain a separated product. The method can inhibit and delay the thermal cracking rate of the heat transfer oil for the mixture of the polychlorinated pyridine compound and the heat transfer oil, effectively separate the polychlorinated pyridine compound and the heat transfer oil, improve the safety and be suitable for industrial production.
Description
Technical Field
The invention belongs to the technical field of organic fine chemical engineering, and particularly relates to a separation method of a polychlorinated pyridine compound and heat-conducting oil mixture.
Background
The polychlorinated pyridine compound is widely applied to production and life of people as an important medicine and pesticide intermediate.
The known polychlorinated pyridine compounds are synthesized by chlorination of pyridine compounds by chlorine, and in order to improve the reaction rate, the reaction is mostly carried out at a higher temperature, and the heating medium is generally heat-conducting oil. In order to reduce the corrosion of chlorine ions in the reactants to the reactor, an economical corrosion-resistant steel-lined enamel container is usually selected as the reactor. Because the coefficients of thermal expansion of the enamel and the carbon steel are different, the enamel is broken due to rapid cooling and rapid heating in the processes of temperature rise and drop of materials in the heat transfer oil and the reactor, the wall of the reactor is caused by accelerated corrosion of chlorine-containing materials, and the heat transfer oil is connected into the reactor in series to generate a mixture of a polychlorinated pyridine compound and heat transfer oil. Although the temperature difference of heating and cooling is strictly controlled in pyridine chlorination production, the temperature difference is influenced by corrosion of chloride ions on enamel, the enamel performance is poor, and the condition that heat conduction oil is connected into a reactor in series still happens occasionally.
The method comprises the steps of mixing a polychlorinated pyridine compound and heat conducting oil, wherein the chloropyridine is usually solid at normal temperature, the heat conducting oil is liquid and is dissolved with a small amount of chloropyridine, and separating oil-mixed materials by selecting extraction solvents with different polarities, such as benzene, toluene, o-dichlorobenzene, hexane, cyclohexane, n-heptane, methanol, ethanol, acetone and the like through operations of temperature rise and drop, liquid separation, crystallization and the like. The mixture of the chloropyridine compound and the heat conduction oil has a high boiling point, the direct high-temperature distillation and long-time heat storage can accelerate the initiation of the tar formation of materials and even the expansion coking under the action of the heat conduction oil, certain potential safety hazards exist, and the treatment cost of solid waste is very high.
An additive is provided in the mixture of the polychlorinated pyridine compound and the heat conducting oil, and the possibility of delaying the generation of coking and carbonization in a distillation separation period is realized. The decomposition of the heat conduction oil is usually local thermal cracking and oxidation, the high-temperature thermal cracking and oxidation processes are both free radical reactions, the addition of the antioxidant is mostly seen in the application process of the heat conduction oil, the amine antioxidant, the phenol antioxidant, the metal ion chelating agent and other components are added into the heat conduction oil to capture and absorb active free radicals, the chain initiation and growth reactions are inhibited, the metal ion activity is inhibited, the purposes of resisting oxidation and scale are achieved, and the operation stability of the heat conduction oil is improved.
In the distillation separation process of the polychlorinated pyridine compound and the heat-conducting oil mixture, most of pyridine chlorination process reactors are made of steel-lined enamel materials, active metal ions are removed, the polychlorinated pyridine compound is easy to deteriorate due to the addition of excessive active ingredients, in order to ensure that the polychlorinated pyridine compound is not damaged and the thermal cracking speed of the heat-conducting oil is inhibited or slowly released, the high-temperature distillation process of the polychlorinated pyridine compound and the heat-conducting oil mixture delays the inhibition of the thermal cracking speed of the heat-conducting oil, and the selection of an appropriate antioxidant is tried to become a method for breaking through the safe and efficient separation of the pyridine compound and the heat-conducting oil mixed oil material.
Disclosure of Invention
Aiming at the treatment difficulties, the invention provides a method for distilling and separating a polychlorinated pyridine compound and a heat-conducting oil mixture at high temperature by adopting a free radical absorbent and a diluent under the assistance of an auxiliary agent, and the method not only realizes the separation of the polychlorinated pyridine compound and the heat-conducting oil, but also is beneficial to inhibiting the generation of tar in the process of distilling the polychlorinated pyridine compound.
The invention relates to a distillation separation method of a polychlorinated pyridine compound and heat-conducting oil mixture, which comprises the following steps: cooling the mixture of the polychlorinated pyridine compound and the heat conduction oil, adding a free radical absorbent and a diluent into the solid attached with the polychlorinated pyridine compound for dissolving, adding an auxiliary agent into the solution, heating, distilling under reduced pressure to collect the fraction, and dissolving and refining the collected fraction and the polar solvent to obtain a separated product.
Further, in the above technical scheme, the adopted technical scheme comprises the following specific reaction steps:
1. cooling the mixture of the polychlorinated pyridine compound and the heat-conducting oil to 0-5 ℃, separating out liquid heat-conducting oil, weighing the solid of the mixture, putting the solid of the mixture into a distiller, adding a free radical absorbent accounting for 0.1-0.3 time of the mass of the solid of the mixture and a diluent accounting for 0.3-0.5 time of the mass of the solid of the mixture, heating to 50-70 ℃, adding an auxiliary agent accounting for 0.01-0.05 time of the mass of the solid of the mixture after the solution is clarified, and uniformly stirring.
2. Gradually heating the distiller, maintaining the vacuum degree at-0.08 MPa to-0.01 MPa, and recovering the polychlorinated pyridine compound components under reduced pressure, wherein when the distiller does not produce distillation any more, the recovery is finished.
3. Mixing the collected fraction of the polychlorinated pyridine compound with a polar solvent according to the mass ratio of 1:1-2, heating to 40-50 ℃, keeping the temperature, stirring, cooling to 5-10 ℃, crystallizing, filtering to obtain a separated product, and distilling the polar solvent in the mother liquor under reduced pressure for recycling.
Further, in the above technical scheme, the radical absorbent is one or more of 2, 3-dichloro-5-trifluoromethylpyridine-6-phenol, 2, 6-di-tert-butylphenol, and vitamin E.
Further, in the above technical solution, the diluent is one or more of N-methylpyrrolidone, diphenyl ether, dodecane, and glycerol.
Further, in the above technical solution, the auxiliary agent is one or more of sodium chloride, calcium chloride, and calcium oxide.
Further, in the above technical scheme, the highest distillation temperature does not exceed 195 ℃.
Further, in the above technical solution, the polar solvent is one or more of methanol, ethanol, isopropanol, and acetonitrile.
The invention has the following advantages:
1) the invention selects a free radical absorbent for preventing the pyrolysis of heat conduction oil in chloropyridine compound oil strings at high temperature for the first time, and provides a method for inhibiting and delaying coking and decarburization of materials caused by a heat conduction oil chain reaction.
2) The material is diluted by the high-boiling point diluent, the concentration of heat conduction oil in the material is reduced, the material reduction in the later period of distillation is prevented, the concentration enrichment and cracking rate of the heat conduction oil is accelerated, and the free radical absorbent cannot absorb the heat conduction oil in time, so that the material coking and decarburization reaction is initiated, the addition of the diluent is favorable for the residual tar in a kettle to be easily discharged, and the adhesion of the wall due to the dry burning of the tar in the material is prevented.
3) The boiling point of the polychlorinated pyridine compound is reduced by vacuum distillation, the accumulation of high-temperature side reaction is avoided, and the recovery period is shortened.
4) The polar solvent has certain solubility to the materials, meets the refining and purification requirements, and prevents the yield effect from being reduced due to the introduction of the non-polar solvent.
5) According to different pollution amounts of heat conducting oil, the recovery rate of materials can reach 70-90% after the treatment by the method.
Drawings
FIG. 1 is a flow chart of a separation method according to the present invention.
Wherein A represents waste heat conducting oil, B represents a solid mixture of a polychlorinated pyridine compound and heat conducting oil, C represents a free radical absorbent, D represents a diluent, E represents tar kettle residue, F represents distillation collected fraction, G represents a polar solvent, H represents desolventizing kettle residue, and J represents a separation product.
FIG. 2 is a table of the solubility of CTC in methanol in example 1.
Detailed Description
The present invention will be further specifically described below by way of specific examples, but it should not be construed as limiting the scope of the present invention.
Example 1:
cooling 2-chloro-6-trichloromethylpyridine (CTC for short) oil material in a string to 0-5 ℃, separating liquid heat conducting oil, weighing 400kg of solid oil material in a vacuum distillation kettle, adding 20kg of 95% 2, 3-dichloro-5-trifluoromethylpyridine-6-phenol and 30kg of 98% 2, 6-di-tert-butylphenol, adding 150kg of 99% isododecane, and heating to 50-70 ℃, preferably 60 ℃. After the solution is dissolved, 10kg of anhydrous calcium chloride with the content of 95 percent is added, the stirring is started, and the stirring is uniform.
Starting heat conduction oil to slowly heat the reduced pressure distillation kettle, starting a vacuum pump to vacuum the distillation kettle, keeping the vacuum degree between minus 0.08MPa and minus 0.01MPa, collecting distillate when the distillation kettle starts to produce the distillate, collecting the distillate when the temperature of the kettle is increased to 185 ℃, keeping the distillate for 0.5 hour, and starting cold heat conduction oil to cool after the collection is finished. When the temperature of the kettle is reduced to 100 ℃, discharging residual liquid in the kettle. The temperature of the collecting tank is kept between 80 and 100 ℃, and 334kg of fraction is collected in the reduced pressure distillation kettle.
And (2) transferring the dissolving kettle into 500kg of methanol, putting 334kg of fraction collected by the reduced pressure distillation kettle into the dissolving kettle, stirring and heating, heating to 45 ℃, keeping the temperature for half an hour, transferring into a product crystallization kettle, introducing cold saline water, cooling to 5-10 ℃, discharging and centrifuging to obtain 224.5kg of wet product, wherein the wet product is white, transferring the mother solution of the product into a mother solution desolventizing kettle, distilling the methanol under reduced pressure at 80 ℃, recycling and reusing the mother solution, and finally, storing in a mother solution kettle. Determining 3 times of quantitative average content of the serial oil CTC solid material to be 77.25%, wherein the product yield of CTC is as follows: 81.60 percent.
Example 2:
cooling 2-chloro-6-trichloromethylpyridine oil strings to below 5 ℃, separating liquid heat conduction oil, weighing 500kg of solid oil strings, putting the solid oil strings into a reduced pressure distillation kettle, starting the heat conduction oil to slowly heat the reduced pressure distillation kettle, starting a vacuum pump to vacuum the distillation kettle, keeping the vacuum degree between-0.08 MPa and-0.01 MPa, collecting distillate when the distillation kettle starts to produce the distillate, when the temperature of the kettle rises to 180 ℃, the vacuum fluctuates, white smoke appears in the distillation kettle, heating of the heat conduction oil is stopped, cold heat conduction oil is introduced for cooling, the temperature of the kettle rises to 198 ℃ rapidly without external source heating, and the temperature of the kettle keeps gentle after continuing to rise to 298 ℃. Materials in the simple distillation kettle are expanded, coked and carbonized, and 176kg of distillate is collected. (preliminary experiment small test card without coking and carbonization)
Example 3:
cooling 2, 3-dichloro-5-trichloromethylpyridine oil strings to 0-5 ℃, separating liquid heat conduction oil, weighing 5kg of solid oil strings, putting the solid oil strings into a 5L distiller, controlling the oil bath temperature to be 180 ℃, slowly heating the distiller, starting a water ring vacuum pump to vacuumize the distiller, keeping the vacuum degree between-0.07 MPa and-0.09 MPa, collecting distillate from the distiller, collecting for 11.5 hours, and when the kettle temperature is increased to 174 ℃, finding that the vacuum degree is slowly reduced, generating a small amount of smoke in the distiller, obviously sticking the materials in the kettle, stopping heating, obviously obtaining tar-like materials, reducing the temperature to normal temperature, and solidifying the materials in the distiller in a coke-like manner.
The foregoing embodiments have described the general principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the present invention, and that various changes and modifications may be made without departing from the scope of the principles of the present invention, and the invention is intended to be covered by the appended claims.
Claims (7)
1. A method for separating a polychlorinated pyridine compound and a heat-conducting oil mixture is characterized by comprising the following operations: cooling the mixture of the polychlorinated pyridine compound and the heat conduction oil, adding a free radical absorbent and a diluent into the solid attached with the polychlorinated pyridine compound for dissolving, adding an auxiliary agent into the solution, heating, distilling under reduced pressure to collect the fraction, and dissolving and refining the collected fraction and the polar solvent to obtain a separated product.
2. The method for separating the mixture of polychlorinated pyridine compounds and thermal conductive oil according to claim 1, wherein the specific reaction steps are as follows: firstly, cooling a mixture of a polychlorinated pyridine compound and heat-conducting oil to 0-5 ℃, separating out liquid heat-conducting oil, weighing the solid mixture, putting the solid mixture into a distiller, adding a free radical absorbent accounting for 0.1-0.3 time of the solid mass of the mixture and a diluent accounting for 0.3-0.5 time of the solid mass of the mixture, heating to 50-70 ℃, adding an auxiliary agent accounting for 0.01-0.05 time of the solid mass of the mixture after the solution is clarified, and uniformly stirring; step two, gradually heating the distiller, maintaining the vacuum degree between minus 0.08MPa and minus 0.01MPa, decompressing and collecting the polychlorinated pyridine compound components, and finishing the collection when the distiller does not distill any more; thirdly, mixing the collected fraction of the polychlorinated pyridine compound with a polar solvent according to the mass ratio of 1:1-2, heating to 40-50 ℃, keeping the temperature, stirring, cooling to 5-10 ℃, crystallizing, filtering to obtain a separated product, and distilling the polar solvent in the mother liquor under reduced pressure for recycling.
3. The method for separating a mixture of a polychlorinated pyridine compound and a thermal oil according to claim 1 or 2, wherein: the free radical absorbent is one or more of 2, 3-dichloro-5-trifluoromethylpyridine-6-phenol, 2, 6-di-tert-butylphenol and vitamin E.
4. The method for separating a mixture of a polychlorinated pyridine compound and a thermal oil according to claim 1 or 2, wherein: the diluent is one or more of N-methyl pyrrolidone, diphenyl ether, dodecane and glycerol.
5. The method for separating a mixture of a polychlorinated pyridine compound and a thermal oil according to claim 1 or 2, wherein: the auxiliary agent is one or more of sodium chloride, calcium chloride and calcium oxide.
6. The method for separating a mixture of a polychlorinated pyridine compound and a thermal oil according to claim 1 or 2, wherein: the maximum distillation temperature does not exceed 195 ℃.
7. The method for separating a mixture of a polychlorinated pyridine compound and a thermal oil according to claim 1 or 2, wherein: the polar solvent is one or more of methanol, ethanol, isopropanol and acetonitrile.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB391435A (en) * | 1931-09-21 | 1933-04-21 | Ici Ltd | Cleansing and softening agent |
| US3786044A (en) * | 1971-05-19 | 1974-01-15 | Ciba Geigy Corp | (6-pyrrol-1-yl)-3-pyridineacetic acid derivatives |
| CN106978242A (en) * | 2017-04-27 | 2017-07-25 | 山东英可利化工有限公司 | Conduction oil antioxidant and anti-oxidation method |
| US20200299204A1 (en) * | 2017-10-03 | 2020-09-24 | Michael Schelch | Method for recovering valuable substances |
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2020
- 2020-11-06 CN CN202011233715.3A patent/CN112250618B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB391435A (en) * | 1931-09-21 | 1933-04-21 | Ici Ltd | Cleansing and softening agent |
| US3786044A (en) * | 1971-05-19 | 1974-01-15 | Ciba Geigy Corp | (6-pyrrol-1-yl)-3-pyridineacetic acid derivatives |
| CN106978242A (en) * | 2017-04-27 | 2017-07-25 | 山东英可利化工有限公司 | Conduction oil antioxidant and anti-oxidation method |
| US20200299204A1 (en) * | 2017-10-03 | 2020-09-24 | Michael Schelch | Method for recovering valuable substances |
Non-Patent Citations (2)
| Title |
|---|
| LAURA J. ALLEN，等: "Developing Efficient Nucleophilic Fluorination Methods and Application to Substituted Picolinate Esters", 《ORGANIC PROCESS RESEARCH & DEVELOPMENT》 * |
| 汪琦，等: "提高导热油炉热效率方法探讨", 《染整技术》 * |
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