CN112390746A - Method for inhibiting generation of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity - Google Patents
Method for inhibiting generation of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity Download PDFInfo
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- CN112390746A CN112390746A CN202011212077.7A CN202011212077A CN112390746A CN 112390746 A CN112390746 A CN 112390746A CN 202011212077 A CN202011212077 A CN 202011212077A CN 112390746 A CN112390746 A CN 112390746A
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- trifluoromethylpyridine
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- cyano
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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
- C07D213/78—Carbon atoms having three bonds to hetero atoms, with at the most one bond to halogen, e.g. ester or nitrile radicals
- C07D213/84—Nitriles
Abstract
The invention discloses a method for inhibiting 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity, belonging to the field of organic chemistry. The specific operation is as follows: adding an inhibitor into the 2-cyano-3-chloro-5-trifluoromethylpyridine concentrated solution, heating for reaction for a period of time, removing water by water vapor distillation, separating out water, filtering to remove salt, adding the inhibitor and sulfolane, and rectifying to obtain the high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine. The method has the advantages of simple process, easy operation and low production cost, and the obtained 2-cyano-3-chloro-5-trifluoromethylpyridine has the purity as high as 99.5 percent and the yield as high as 98 percent.
Description
Technical Field
The invention belongs to the field of organic chemistry, and particularly relates to a method for inhibiting generation of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity.
Technical Field
The 2-cyano-3-chloro-5-trifluoromethylpyridine is an important pesticide intermediate and is mainly used for producing pesticide chemical products such as 2-methylamino-3-chloro-5-trifluoromethylpyridine hydrochloride, fluoroether bacteria amide and the like.
In the prior art, 2, 3-dichloro-5-trifluoromethylpyridine is used as a raw material to react with 4-dimethylamino pyridine, pyridine salt after crystallization and drying reacts with potassium cyanide or sodium cyanide, and the 2-cyano-3-chloro-5-trifluoromethylpyridine is obtained by washing and distillation, wherein the yield is 80%. The operation process is complicated, the yield is low, the generated cyanogen-containing wastewater is extremely high, the post-treatment is difficult, and the long-term industrial production is not facilitated.
In recent years, 2-fluoro-3-chloro-5-trifluoromethylpyridine and potassium (sodium) cyanide are directly reacted to obtain 2-cyano-3-chloro-5-trifluoromethylpyridine, and side reaction impurities are generated in the purification process through water washing, distillation and rectification to obtain 98% of 2-cyano-3-chloro-5-trifluoromethylpyridine product. The product contains nearly 2 percent of impurities, the separation difficulty of the impurities and the boiling point of the 2-cyano-3-chloro-5-trifluoromethylpyridine is large, and the high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine is difficult to obtain.
Disclosure of Invention
The invention provides a method for inhibiting generation of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity.
The invention can realize the purpose by the following ways, and adopts the following specific scheme:
a method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor, comprising the steps of:
1) adding an inhibitor aqueous solution into the 2-cyano-3-chloro-5-trifluoromethylpyridine concentrated solution, and heating to react to inhibit the 2-cyano-3-chloro-5-trifluoromethylpyridine from being converted into a precursor impurity;
2) adding water into the solution obtained in the step 1) for steam distillation, and separating out water to obtain an anhydrous organic phase;
3) filtering the organic phase obtained in the step 2) into a rectifying still, removing residual salt, adding a solution consisting of an inhibitor and sulfolane again, and rectifying to obtain the high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine.
Further, in the above technical solution, the inhibitor is calcium chloride, ferric chloride, calcium oxide or calcium hydroxide.
Further, in the above technical scheme, the molar ratio of the inhibitor to 2-cyano-3-chloro-5-trifluoromethyl is 1: 50-200, preferably in a molar ratio of 1: 100.
further, in the above technical solution, the concentration of the inhibitor is 5-15 wt%, preferably 10 wt%.
Further, in the technical scheme, the reaction temperature is 40-80 ℃, the reaction time is 3-5h, and the pressure is normal pressure. Preferably 50 ℃ for 4 h.
Further, in the above technical scheme, in the step 2), the steam distillation temperature is atmospheric distillation, and the temperature is 95-100 ℃.
Further, in the above technical solution, in the step 3), the weight of the inhibitor added before the rectification is 0.05-0.5% (preferably 0.4%) of the weight of the concentrated solution. Collecting the distillate at 90-120 deg.C and-0.095 MPa to-0.098 MPa to obtain colorless transparent high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine.
The invention has the beneficial effects
1. The invention provides a method for inhibiting 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity generation, which has the advantages of simple process, easy operation and low production cost.
2. Experiments prove that the purity of the 2-cyano-3-chloro-5-trifluoromethylpyridine obtained by the method can reach 99.5 percent, and the yield can reach 98 percent.
3. The method has the characteristics of high yield, simple treatment, easy operation and low cost, and is suitable for improving the quality of the 2-cyano-3-chloro-5-trifluoromethylpyridine in industrial production.
Detailed Description
The present invention is further illustrated by the following examples.
Example 1
In a 1000mL four-necked flask with stirring, 500g of 2-cyano-3-chloro-5-trifluoromethylpyridine concentrate having a purity of 93.5% and 18.2g of 10% calcium chloride aqueous solution was charged. Stirring is started, the temperature is increased to 50 ℃, and the reaction is carried out for 4 hours.
A water diversion and condensation device is additionally arranged on the four-mouth flask. The temperature is raised to 96 ℃, the organic phase at the lower layer of the water separator is returned to the kettle, and the water layer at the upper layer is collected into a receiving bottle until no water exists in the water separator.
And filtering the residual anhydrous organic phase in the reactor to remove salt, transferring to a rectifying tower, adding 5g of calcium chloride solution dissolved in 10% sulfolane, carrying out reduced pressure rectification, and collecting 460.5g of 2-cyano-3-chloro-5-trifluoromethylpyridine after a part of the previous rectification, wherein the purity is 99.6% and the yield is 98.5%.
Example 2
The calcium chloride in example 1 was changed to ferric chloride to give 458.6g of 2-cyano-3-chloro-5-trifluoromethylpyridine having a purity of 99.5% and a yield of 98.1%.
Example 3
The calcium chloride in example 1 was changed to ferric chloride and the reaction temperature was raised to 70 ℃ to give 2-cyano-3-chloro-5-trifluoromethylpyridine 459.5g with a purity of 99.5% and a yield of 98.3%.
Example 4
5000kg of concentrated solution (the content of a product is detected in a gas phase is 92.5 percent) which is obtained by washing 2-cyano-3-chloro-5-trifluoromethylpyridine generated by the reaction of 2-fluoro-3-chloro-5-trifluoromethylpyridine and potassium cyanide and removing a solvent and concentrating is put into a 5000L reaction kettle with a water separator, 182kg of calcium chloride aqueous solution is added, and the temperature is raised to 50 ℃ for reaction for 4 hours. And (3) raising the temperature to 96 ℃, distilling the water vapor, layering the condensed water layer and the condensed oil layer in the water separator, separating the water layer to a water receiving tank, and returning all the oil layer to the kettle until no water is condensed in the water separator. Filtering the residual organic layer in the kettle to remove salt, transferring to a rectifying kettle, adding 50kg of 10% calcium chloride solution dissolved in sulfolane into the kettle, starting stirring, vacuumizing to-0.098 MPa, heating to 90 ℃ and starting harvesting, wherein front distillate (mainly unreacted raw materials) starts harvesting products when the content of 2-cyano-3-chloro-5-trifluoromethylpyridine is more than 98.5%, and the products are harvested until no fraction is produced in a rectifying tower. 320kg of front distillation, 3648kg of 2-cyano-3-chloro-5-trifluoromethylpyridine, 99.75 percent of purity and 98.6 percent of yield are obtained.
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 of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor comprising the steps of: 1) adding an inhibitor aqueous solution into the 2-cyano-3-chloro-5-trifluoromethylpyridine concentrated solution, and heating for reaction to inhibit the generation of precursor impurities; 2) removing water from the solution obtained in the step 1) by water vapor distillation, and separating out the water; 3) and filtering the dehydrated concentrated solution to remove salt, adding a solution consisting of an inhibitor and sulfolane, and rectifying to obtain the high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine.
2. The method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity according to claim 1, wherein: the inhibitor is calcium chloride, ferric chloride, calcium oxide or calcium hydroxide.
3. The method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity according to claim 1, wherein: the molar ratio of the inhibitor to the 2-cyano-3-chloro-5-trifluoromethylpyridine is 1: 50-200.
4. The method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity according to claim 3, wherein: the inhibitor concentration is 5-15 wt%.
5. The method of claim 1 for inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor-hetero, wherein: the reaction temperature is 40-80 ℃, the reaction time is 3-5h, and the pressure is normal pressure.
6. The method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity according to claim 1, wherein: the steam distillation temperature is 95-100 ℃, and normal pressure distillation is adopted.
7. The method of inhibiting the production of 2-cyano-3-chloro-5-trifluoromethylpyridine precursor impurity according to claim 1, wherein: in the rectification and rectification process, sulfolane inhibitor solution with the mass of 0.5 percent of the total mass of the water vapor concentrated solution is added, stirring and distillation are started at the temperature of 90-120 ℃, and the distillate with the pressure of-0.095 to-0.098 MPa is obtained to obtain colorless transparent liquid which is high-purity 2-cyano-3-chloro-5-trifluoromethylpyridine.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106349159A (en) * | 2016-08-29 | 2017-01-25 | 山东省联合农药工业有限公司 | 3-chloro-2-cyano-5-trifluoromethyl pyridine preparation method |
| CN106866510A (en) * | 2017-04-16 | 2017-06-20 | 内蒙古佳瑞米精细化工有限公司 | A kind of preparation method of the trifluoromethyl pyridine of 2 chlorine of high-purity 5 |
| CN106905231A (en) * | 2015-12-23 | 2017-06-30 | 联化科技股份有限公司 | The preparation method of 3- chloro-5-trifluoromethylpyridine class compounds and intermediate |
| CN107286087A (en) * | 2017-04-16 | 2017-10-24 | 内蒙古佳瑞米精细化工有限公司 | A kind of synthetic method of the trifluoromethyl pyridine of 2 cyano group, 3 chlorine 5 |
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- 2020-11-03 CN CN202011212077.7A patent/CN112390746A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106905231A (en) * | 2015-12-23 | 2017-06-30 | 联化科技股份有限公司 | The preparation method of 3- chloro-5-trifluoromethylpyridine class compounds and intermediate |
| CN106349159A (en) * | 2016-08-29 | 2017-01-25 | 山东省联合农药工业有限公司 | 3-chloro-2-cyano-5-trifluoromethyl pyridine preparation method |
| CN106866510A (en) * | 2017-04-16 | 2017-06-20 | 内蒙古佳瑞米精细化工有限公司 | A kind of preparation method of the trifluoromethyl pyridine of 2 chlorine of high-purity 5 |
| CN107286087A (en) * | 2017-04-16 | 2017-10-24 | 内蒙古佳瑞米精细化工有限公司 | A kind of synthetic method of the trifluoromethyl pyridine of 2 cyano group, 3 chlorine 5 |
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Application publication date: 20210223 |