CN116354902A - Green and environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid - Google Patents
Green and environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid Download PDFInfo
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- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 title claims abstract description 78
- 238000000034 method Methods 0.000 title claims abstract description 65
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 title claims abstract description 39
- 235000019253 formic acid Nutrition 0.000 title claims abstract description 39
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 23
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 159
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims abstract description 144
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 121
- 239000007789 gas Substances 0.000 claims abstract description 94
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims abstract description 93
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims abstract description 93
- 238000006243 chemical reaction Methods 0.000 claims abstract description 57
- 238000005660 chlorination reaction Methods 0.000 claims abstract description 35
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims abstract description 31
- 239000000460 chlorine Substances 0.000 claims abstract description 31
- 229910052801 chlorine Inorganic materials 0.000 claims abstract description 31
- 239000012267 brine Substances 0.000 claims abstract description 28
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims abstract description 28
- 230000020477 pH reduction Effects 0.000 claims abstract description 27
- 238000007363 ring formation reaction Methods 0.000 claims abstract description 24
- YVWUNJVPOCYLIM-UHFFFAOYSA-N ethyl 2-chloro-4,4,4-trifluoro-3-oxobutanoate Chemical compound CCOC(=O)C(Cl)C(=O)C(F)(F)F YVWUNJVPOCYLIM-UHFFFAOYSA-N 0.000 claims abstract description 23
- YUKQRDCYNOVPGJ-UHFFFAOYSA-N thioacetamide Chemical compound CC(N)=S YUKQRDCYNOVPGJ-UHFFFAOYSA-N 0.000 claims abstract description 20
- DLFVBJFMPXGRIB-UHFFFAOYSA-N thioacetamide Natural products CC(N)=O DLFVBJFMPXGRIB-UHFFFAOYSA-N 0.000 claims abstract description 20
- OCJKUQIPRNZDTK-UHFFFAOYSA-N ethyl 4,4,4-trifluoro-3-oxobutanoate Chemical compound CCOC(=O)CC(=O)C(F)(F)F OCJKUQIPRNZDTK-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000005904 alkaline hydrolysis reaction Methods 0.000 claims abstract description 17
- 239000002253 acid Substances 0.000 claims abstract description 14
- 239000011230 binding agent Substances 0.000 claims abstract description 14
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 claims description 84
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 56
- 230000001276 controlling effect Effects 0.000 claims description 52
- 239000000243 solution Substances 0.000 claims description 46
- 238000010521 absorption reaction Methods 0.000 claims description 33
- 239000007788 liquid Substances 0.000 claims description 29
- 238000001816 cooling Methods 0.000 claims description 28
- 229910052757 nitrogen Inorganic materials 0.000 claims description 28
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 24
- 238000010438 heat treatment Methods 0.000 claims description 23
- 239000007787 solid Substances 0.000 claims description 22
- 238000001704 evaporation Methods 0.000 claims description 17
- 230000008020 evaporation Effects 0.000 claims description 16
- 239000000706 filtrate Substances 0.000 claims description 16
- 239000011259 mixed solution Substances 0.000 claims description 16
- ILWRPSCZWQJDMK-UHFFFAOYSA-N triethylazanium;chloride Chemical compound Cl.CCN(CC)CC ILWRPSCZWQJDMK-UHFFFAOYSA-N 0.000 claims description 15
- REKJPVUFKQYMHW-UHFFFAOYSA-N 2-methyl-4-(trifluoromethyl)-1,3-thiazole-5-carboxylic acid Chemical compound CC1=NC(C(F)(F)F)=C(C(O)=O)S1 REKJPVUFKQYMHW-UHFFFAOYSA-N 0.000 claims description 13
- 239000012295 chemical reaction liquid Substances 0.000 claims description 13
- 239000011780 sodium chloride Substances 0.000 claims description 13
- 238000003756 stirring Methods 0.000 claims description 13
- 238000010992 reflux Methods 0.000 claims description 11
- 238000005086 pumping Methods 0.000 claims description 10
- 230000001105 regulatory effect Effects 0.000 claims description 8
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 7
- 238000002386 leaching Methods 0.000 claims description 7
- 238000006798 ring closing metathesis reaction Methods 0.000 claims description 7
- 238000007127 saponification reaction Methods 0.000 claims description 7
- 230000035484 reaction time Effects 0.000 claims description 5
- 230000015572 biosynthetic process Effects 0.000 claims description 4
- 238000003786 synthesis reaction Methods 0.000 claims description 3
- 230000006837 decompression Effects 0.000 claims description 2
- 230000000630 rising effect Effects 0.000 claims description 2
- 230000007613 environmental effect Effects 0.000 claims 8
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 abstract description 10
- 239000000575 pesticide Substances 0.000 abstract description 5
- 230000000844 anti-bacterial effect Effects 0.000 abstract description 4
- 239000003899 bactericide agent Substances 0.000 abstract description 4
- 238000004519 manufacturing process Methods 0.000 abstract description 4
- 208000012839 conversion disease Diseases 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 9
- 239000006227 byproduct Substances 0.000 description 6
- 150000003839 salts Chemical class 0.000 description 5
- WOSNCVAPUOFXEH-UHFFFAOYSA-N thifluzamide Chemical compound S1C(C)=NC(C(F)(F)F)=C1C(=O)NC1=C(Br)C=C(OC(F)(F)F)C=C1Br WOSNCVAPUOFXEH-UHFFFAOYSA-N 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 2
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- FKNJDCSKTSRSSW-UHFFFAOYSA-N ethyl 2-methyl-4-(trifluoromethyl)-1,3-thiazole-5-carboxylate Chemical compound CCOC(=O)C=1SC(C)=NC=1C(F)(F)F FKNJDCSKTSRSSW-UHFFFAOYSA-N 0.000 description 2
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 description 2
- 238000001819 mass spectrum Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000003472 neutralizing effect Effects 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- FPKMJPFRDGOUHX-UHFFFAOYSA-N 2-chloro-4,4,4-trifluoro-3-oxobutanoic acid Chemical compound OC(=O)C(Cl)C(=O)C(F)(F)F FPKMJPFRDGOUHX-UHFFFAOYSA-N 0.000 description 1
- GSNUFIFRDBKVIE-UHFFFAOYSA-N DMF Natural products CC1=CC=C(C)O1 GSNUFIFRDBKVIE-UHFFFAOYSA-N 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 241001617088 Thanatephorus sasakii Species 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 238000005755 formation reaction Methods 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 230000002503 metabolic effect Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- YBBRCQOCSYXUOC-UHFFFAOYSA-N sulfuryl dichloride Chemical compound ClS(Cl)(=O)=O YBBRCQOCSYXUOC-UHFFFAOYSA-N 0.000 description 1
- IMFACGCPASFAPR-UHFFFAOYSA-N tributylamine Chemical compound CCCCN(CCCC)CCCC IMFACGCPASFAPR-UHFFFAOYSA-N 0.000 description 1
- YFTHZRPMJXBUME-UHFFFAOYSA-N tripropylamine Chemical compound CCCN(CCC)CCC YFTHZRPMJXBUME-UHFFFAOYSA-N 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
- C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
- C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
- C07D277/32—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members 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
- C07D277/56—Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to a green environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, belonging to the technical field of pesticide bactericide production. Preparing ethyl chlorotrifluoroacetoacetate by reacting ethyl trifluoroacetoacetate with chlorine, then carrying out cyclization reaction on the ethyl chlorotrifluoroacetoacetate, thioacetamide and triethylamine serving as an acid binding agent to obtain a cyclization product, and finally carrying out alkaline hydrolysis and acidification reaction on the cyclization product to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; in the invention, the generated hydrogen chloride gas is absorbed through the brine in the chlorination reaction process, so that the chlorination reaction is promoted to be carried out rightwards, and the yield of the chloro-trifluoro-acetoacetic acid ethyl ester is improved; sodium hydroxide is added in the cyclization process, and the reaction conversion rate is synergistically improved by the aid of the sodium hydroxide and the acid binding agent triethylamine; in the alkaline hydrolysis process, the vacuum degree is controlled to be-0.06 to-0.09 MPa, and the reaction temperature is 43-45 ℃, so that ethanol generated by the reaction is rapidly distilled off, and the yield of alkaline hydrolysis products is improved.
Description
Technical Field
The invention belongs to the technical field of pesticide bactericide production, and relates to a green and environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid.
Background
In recent years, the development of fluorine-containing pesticides has been active, and Thifluzamide (Thifluzamide) is one of them. Thifluzamide is a broad-spectrum bactericide developed and researched by the American Dow company, is mainly used for treating banded sclerotial blight of rice, and is widely paid attention to because of the characteristics of small dosage, low toxicity, high efficacy, strong metabolic capability and the like of the pesticide.
2-methyl-4-trifluoromethyl-5-thiazole formic acid is an important intermediate for synthesizing thifluzamide, and the synthetic route is as follows: the ethyl trifluoroacetoacetate is chloridized by chlorine at low temperature or sulfonyl chloride to obtain ethyl 2-chloro-4, 4-trifluoroacetoacetate, the ethyl 2-chloro-4, 4-trifluoroacetoacetate and thioacetamide are cyclized in acetonitrile or DMF or acetic acid to obtain 2-methyl-4-trifluoromethyl-5-ethoxycarbonyl thiazole, and the 2-methyl-4-trifluoromethyl-5-ethoxycarbonyl thiazole is hydrolyzed under alkaline condition and then acidized to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid.
In the existing synthesis process of 2-methyl-4-trifluoromethyl-5-thiazole formic acid, the utilization rate of byproducts is low, the problem of environmental pollution is caused by wastewater discharge, and the yield and purity of 2-methyl-4-trifluoromethyl-5-thiazole formic acid are required to be further improved.
For example, chinese patent CN201610747713 discloses a preparation method of 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which takes 2-chloro-4, 4-trifluoro acetoacetic acid ethyl ester and thioacetamide as raw materials, tri-n-propylamine or tri-n-butylamine as an acid binding agent, and the 2-methyl-4-trifluoromethyl-5-thiazole formic acid is obtained through chain formation, ring formation, hydrolysis and acidification. But the byproducts in the whole process are not recycled, and the purity of the product is up to 95.3 percent, and the yield is up to 90.8 percent.
Chinese patent publication No. CN201510389311 discloses a green environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the steps of mixing ethyl trifluoroacetoacetate, acetonitrile and a catalyst, introducing chlorine gas and hydrogen sulfide gas for carrying out chlorination and cyclization reaction, and has the advantages of completing the chlorination and cyclization reaction by a one-step method, greatly shortening the reaction time and improving the yield of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid. Also, the whole process does not recycle byproducts, the purity of the product is 97.02% at the highest, and the yield is 85.05% at the highest.
Disclosure of Invention
The invention aims to provide a green and environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, and belongs to the technical field of pesticide bactericide production. Preparing ethyl chlorotrifluoroacetoacetate by reacting ethyl trifluoroacetoacetate with chlorine, then carrying out cyclization reaction on the ethyl chlorotrifluoroacetoacetate, thioacetamide and triethylamine serving as an acid binding agent to obtain a cyclization product, and finally carrying out alkaline hydrolysis and acidification reaction on the cyclization product to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; in the invention, the generated hydrogen chloride gas is absorbed through the brine in the chlorination reaction process, so that the chlorination reaction is promoted to be carried out rightwards, and the yield of the chloro-trifluoro-acetoacetic acid ethyl ester is improved; sodium hydroxide is added in the cyclization process, and the reaction conversion rate is synergistically improved by the aid of the sodium hydroxide and the acid binding agent triethylamine; in the alkaline hydrolysis process, the vacuum degree is controlled to be-0.06 to-0.09 MPa, and the reaction temperature is 43-45 ℃, so that ethanol generated by the reaction is rapidly distilled off, and the yield of alkaline hydrolysis products is improved. The byproducts of the whole production process are recycled, the environment is protected, the purity of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid reaches more than 96%, and the yield reaches more than 92%.
The aim of the invention can be achieved by the following technical scheme:
an environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle by a pump under the protection of nitrogen, cooling, introducing chlorine, controlling the temperature, heating to react after introducing the chlorine, and finally introducing nitrogen to expel hydrogen chloride gas in the reaction liquid to obtain ethyl chlorotrifluoroacetoacetate;
(2) And (3) ring closure: under the protection of nitrogen, acetonitrile is pumped into a closed loop kettle by a pump, solid sodium hydroxide is added through a solid feeder, stirring is started, temperature is controlled, thioacetamide is added, ethyl chlorotrifluoroacetoacetate is dripped through a metering tank, temperature is controlled after dripping is finished, triethylamine is dripped, heating reflux reaction is carried out after dripping is finished, triethylamine hydrochloride is filtered after the reaction liquid is cooled, and acetonitrile and triethylamine are distilled out from filtrate under reduced pressure and then are led into a closed loop liquid metering tank;
(3) Alkaline hydrolysis and acidification: preparing sodium hydroxide solution in a saponification kettle, cooling, then dropwise adding a closed-loop liquid metering tank filtrate, reducing pressure, heating for reaction, adding deionized water after the reaction is completed, controlling the temperature, dropwise adding a hydrochloric acid solution, centrifugally separating, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid.
As a preferable technical scheme of the invention, the cooling temperature in the step (1) is-3 to-7 ℃; the temperature control means controlling the temperature to be 5-10 ℃; the chlorine is introduced for 18-22 hours; the heating is to heat to 20-25 ℃; the reaction time is 2.8-3.2h.
As a preferable technical scheme of the invention, in the reaction process of the step (1), an absorption chamber is arranged in the chlorination reactor, and the absorption chamber is used for storing brine for absorbing hydrogen chloride gas generated in the reaction process; and (3) introducing nitrogen to remove the hydrogen chloride gas in the reaction liquid, and then absorbing the hydrogen chloride gas by using saline.
As a preferable technical scheme of the invention, the brine after absorbing the hydrogen chloride gas enters an evaporation tower to be heated and evaporated to obtain the hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for the subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration.
As a preferable technical scheme of the invention, the temperature is controlled in the step (2) and thioacetamide is added to the mixture to control the temperature to be 20-25 ℃; controlling the temperature and dropwise adding ethyl chlorotrifluoroacetoacetate into a metering tank to control the temperature to 15-25 ℃; the dropwise adding of the chloro-trifluoro-acetoacetic acid ethyl ester is completed after 3-4 hours of dropwise adding; the temperature control reaction after the completion of the dripping is that the reaction is carried out for 2.8 to 3.2 hours at the temperature of 20 to 25 ℃; the dripping triethylamine is controlled to be 1.5-2 hours after the dripping is finished; the thermal reflux reaction is reflux reaction for 2.8-3.2h at 76-78 ℃; the cooling of the reaction liquid means cooling to below 25 ℃.
As a preferable technical scheme of the invention, the filtered triethylamine hydrochloride in the step (2) is put into a sodium hydroxide solution, stirred, stood and layered, and triethylamine is recovered from the upper layer for being used as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated.
As a preferable technical scheme of the invention, the acetonitrile and triethylamine distilled off under reduced pressure in the step (2) are reused for the cyclization reaction in the step (2).
As a preferable technical scheme of the invention, the mass concentration of the sodium hydroxide solution in the step (3) is 45-55%; the cooling refers to cooling to 20-25 ℃; the filtrate of the dripping closed-loop liquid metering tank is controlled to be 2.8-3.2 hours after the dripping is finished; the decompression and temperature rising reaction means that the vacuum degree is controlled to be-0.06 to-0.09 MPa, the reaction temperature is controlled to be 43-45 ℃, and the reaction time is controlled to be 2.8-3.2 hours; the temperature control means controlling the temperature to be 20-25 ℃; the mass concentration of the hydrochloric acid solution is 30-35%; the drop adding amount of the hydrochloric acid solution controls the pH value of the system to be 1-2.
As a preferable technical scheme of the invention, the centrifugally separated liquid in the step (3) enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is recycled for an acidification process by adjusting the concentration, and the evaporated liquid is recycled for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration.
As a preferable technical scheme of the invention, the molar ratio of the addition of the ethyl trifluoroacetoacetate, the chlorine, the solid sodium hydroxide, the thioacetamide, the triethylamine and the sodium hydroxide solution in the synthesis process of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid is 1:1.2-1.6:0.1-0.2:1.06-1.08:1.8-2.4:1.9-2.5.
The invention has the beneficial effects that:
(1) In the chlorination reaction process, the absorption chamber is arranged in the chlorination reactor, the generated hydrogen chloride gas is absorbed through the brine, and the brine can selectively absorb the hydrogen chloride gas and hardly absorb the chlorine, so that the chlorination reaction is promoted to right and the yield of the chloro-trifluoroacetoacetate is improved while the loss of reaction raw materials is avoided; after the chlorination reaction is finished, introducing nitrogen to drive out residual hydrogen chloride gas, absorbing the residual hydrogen chloride gas by using salt water, and simultaneously driving out a small amount of residual chlorine gas, so that side reactions in a reaction system are further reduced, and the purity of a product is improved;
(2) According to the method, a small amount of solid sodium hydroxide is added in the cyclization reaction process, the sodium hydroxide and triethylamine can both play a role in neutralizing byproduct hydrochloric acid in the cyclization reaction process, the cyclization reaction is promoted to be carried out rightwards, the yield of a cyclization product is effectively improved, and a product sodium chloride solution obtained by neutralizing the sodium hydroxide and the hydrochloric acid can be used for absorbing hydrogen chloride gas in the chlorination reaction process;
(3) The vacuum degree is controlled to be-0.06 to-0.09 MPa in the alkaline hydrolysis process, and the reaction temperature is 43-45 ℃, so that ethanol generated in the alkaline hydrolysis reaction process is rapidly distilled, the yield of alkaline hydrolysis products is improved, and the subsequent step of removing ethanol by reduced pressure distillation is omitted;
(4) The method comprises the steps that brine which absorbs hydrogen chloride gas in the chlorination reaction enters an evaporation tower to be heated and evaporated to obtain the hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for the subsequent acidification process, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the chlorination reaction process after the concentration of the brine is adjusted; adding triethylamine hydrochloride filtered in the cyclization reaction process into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer to alleviate an acid binding agent in the reaction process; the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the chlorination reaction process after the concentration is regulated; distilling acetonitrile and triethylamine under reduced pressure in the cyclization reaction process, wherein the acetonitrile is reused as a solvent, and the triethylamine is reused as an acid binding agent; the liquid after centrifugal separation in the alkaline hydrolysis and acidification reaction process contains sodium chloride and hydrochloric acid, enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, is absorbed by a water absorption tower and then is recycled for the acidification process by adjusting the concentration, and the evaporated liquid contains sodium chloride and is recycled for absorbing the hydrogen chloride gas generated in the chlorination reaction process by adjusting the concentration; the byproducts and the solvent in the whole process are recycled, so that the method is green and environment-friendly, and meanwhile, the purity and the yield of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid can be improved, the purity of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid can reach more than 96%, and the yield of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid can reach more than 92%.
Drawings
The present invention is further described below with reference to the accompanying drawings for the convenience of understanding by those skilled in the art.
FIG. 1 is a liquid chromatogram of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in example 1, wherein the detector is an ultraviolet detector, and the detection wavelength is 245nm.
FIG. 2 is a mass spectrum of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in example 1.
Detailed Description
In order to further describe the technical means and effects adopted by the present invention for achieving the intended purpose, the following detailed description is given below with reference to the embodiments, structures, features and effects according to the present invention.
Example 1
An environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle under the protection of nitrogen, cooling to the temperature of minus 5 ℃, then introducing chlorine, controlling the temperature to 8 ℃, controlling the temperature to be 20 hours, after introducing the chlorine, heating to the temperature of 22 ℃ for reaction for 3 hours, setting an absorption chamber in the chlorination kettle, storing salt water in the absorption chamber for absorbing hydrogen chloride gas generated in the reaction process, and after the reaction is completed, introducing nitrogen to remove residual hydrogen chloride gas and a small amount of chlorine in the reaction liquid to obtain ethyl chlorotrifluoroacetoacetate; residual hydrogen chloride gas removed by nitrogen is absorbed by brine and then is put into an evaporation tower together with the brine absorbed by the hydrogen chloride gas in an absorption chamber to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for a subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration;
(2) And (3) ring closure: under the protection of nitrogen, acetonitrile is pumped into a closed loop kettle by a pump, solid sodium hydroxide is added through a solid feeder, stirring is started, the temperature is controlled to 25 ℃, thioacetamide is added, the temperature is controlled to 20 ℃, ethyl chlorotrifluoroacetoacetate is dripped through a metering tank, the dripping is controlled to be finished, the temperature is controlled to 25 ℃ after the dripping is finished, the reaction is carried out for 3 hours, triethylamine is dripped, the dripping is controlled to be finished, the reaction is heated to 76 ℃ after the dripping is finished, the reflux reaction is carried out for 3 hours, the reaction liquid is cooled to below 25 ℃, triethylamine hydrochloride is filtered, the filtrate is decompressed and distilled out, and then the acetonitrile and the triethylamine are led into a closed loop liquid metering tank; adding the filtered triethylamine hydrochloride into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer for use as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated; the acetonitrile and triethylamine distilled under reduced pressure are reused for the cyclization reaction of the step (2);
(3) Alkaline hydrolysis and acidification: preparing a sodium hydroxide solution with the mass concentration of 50% in a saponification kettle, controlling the molar ratio of the ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution to be 1:1.2:0.15:1.06:1.9:2.2, cooling to 25 ℃, dropwise adding a closed-loop solution metering tank filtrate, controlling the dropwise adding to 3 hours, reducing the pressure to the vacuum degree of-0.06 to-0.09 MPa, heating to 45 ℃ for reacting for 3 hours, adding deionized water after the reaction is finished, controlling the temperature to 25 ℃ and dropwise adding a hydrochloric acid solution with the mass concentration of 31%, controlling the pH value of a system to be 1-2, centrifugally separating, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; the centrifugally separated liquid enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for an acidification process by adjusting the concentration, and the evaporated liquid is used for absorbing the hydrogen chloride gas generated in the step (1) by adjusting the concentration.
The purity of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in this example was 96.38%, and the yield was 92.62%.
The liquid chromatogram of the 2-methyl-4-trifluoromethyl-5-thiazole formic acid prepared in the embodiment detected by the liquid chromatogram with the external color detector is shown in figure 1, and the mass spectrum detected by the mass spectrometer is shown in figure 2.
Example 2
An environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle under the protection of nitrogen, cooling to the temperature of minus 3 ℃, then introducing chlorine, controlling the temperature to be 10 ℃, controlling the temperature to be 22 hours, heating to the temperature of 25 ℃ after introducing the chlorine, reacting for 3.1 hours, arranging an absorption chamber in the chlorination kettle, storing salt water in the absorption chamber for absorbing hydrogen chloride gas generated in the reaction process, and introducing nitrogen to drive out residual hydrogen chloride gas and a small amount of chlorine in the reaction liquid after the reaction is completed, so as to obtain ethyl chlorotrifluoroacetoacetate; residual hydrogen chloride gas removed by nitrogen is absorbed by brine and then is put into an evaporation tower together with the brine absorbed by the hydrogen chloride gas in an absorption chamber to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for a subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration;
(2) And (3) ring closure: under the protection of nitrogen, acetonitrile is pumped into a closed loop kettle by a pump, solid sodium hydroxide is added through a solid feeder, stirring is started, the temperature is controlled to 24 ℃, thioacetamide is added, the temperature is controlled to 22 ℃, ethyl chlorotrifluoroacetoacetate is dripped through a metering tank, the dripping is controlled to be completed, the temperature is controlled to 22 ℃ after the dripping is completed for 3.2 hours, triethylamine is dripped, the dripping is controlled to be completed for 1.8 hours, the reflux reaction is heated to 78 ℃ after the dripping is completed for 2.9 hours, the reaction solution is cooled to below 25 ℃, triethylamine hydrochloride is filtered, the acetonitrile and the triethylamine are distilled out from the filtrate under reduced pressure and then are led into the closed loop solution metering tank; adding the filtered triethylamine hydrochloride into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer for use as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated; the acetonitrile and triethylamine distilled under reduced pressure are reused for the cyclization reaction of the step (2);
(3) Alkaline hydrolysis and acidification: preparing 48% sodium hydroxide solution in a saponification kettle, controlling the molar ratio of ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution to be 1:1.5:0.1:1.08:2:2.5, cooling to 23 ℃, dropwise adding a closed-loop solution metering tank filtrate, controlling the dropwise adding to 3.2h, reducing the pressure to the vacuum degree of-0.06 to-0.09 MPa, heating to 43 ℃ for reacting for 3.2h, adding deionized water after the reaction is finished, controlling the temperature to 22 ℃ and dropwise adding 34% hydrochloric acid solution, controlling the pH value of the system to be 1-2, centrifuging, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; the centrifugally separated liquid enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for an acidification process by adjusting the concentration, and the evaporated liquid is used for absorbing the hydrogen chloride gas generated in the step (1) by adjusting the concentration.
The purity of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in this example was 96.16%, and the yield was 92.09%.
Example 3
An environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle under the protection of nitrogen, cooling to the temperature of-7 ℃, then introducing chlorine, controlling the temperature to 5 ℃, controlling the temperature to be 18 hours, heating to the temperature of 20 ℃ after introducing the chlorine, reacting for 3.2 hours, arranging an absorption chamber in the chlorination kettle, storing salt water in the absorption chamber for absorbing hydrogen chloride gas generated in the reaction process, and introducing nitrogen to remove residual hydrogen chloride gas and a small amount of chlorine in the reaction liquid after the reaction is completed, so as to obtain ethyl chlorotrifluoroacetoacetate; residual hydrogen chloride gas removed by nitrogen is absorbed by brine and then is put into an evaporation tower together with the brine absorbed by the hydrogen chloride gas in an absorption chamber to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for a subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration;
(2) And (3) ring closure: under the protection of nitrogen, pumping acetonitrile into a closed loop kettle, adding solid sodium hydroxide through a solid feeder, starting stirring, controlling the temperature to 22 ℃ and adding thioacetamide, controlling the temperature to 25 ℃ and dropwise adding ethyl chlorotrifluoroacetoacetate through a metering tank, controlling the temperature to 20 ℃ after 3.8 hours, reacting for 3 hours, then dropwise adding triethylamine, controlling the temperature to 1.5 hours, heating to 76 ℃ after the dropwise adding is finished, refluxing for 3.2 hours, cooling the reaction solution to below 25 ℃, filtering triethylamine hydrochloride, decompressing and distilling filtrate to obtain acetonitrile and triethylamine, and then introducing the acetonitrile and triethylamine into a closed loop liquid metering tank; adding the filtered triethylamine hydrochloride into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer for use as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated; the acetonitrile and triethylamine distilled under reduced pressure are reused for the cyclization reaction of the step (2);
(3) Alkaline hydrolysis and acidification: preparing 55% sodium hydroxide solution in a saponification kettle, controlling the molar ratio of ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution to be 1:1.6:0.2:1.07:2.4:1.9, cooling to 20 ℃, dropwise adding a closed-loop solution metering tank filtrate, controlling the dropwise adding to 3.2h, reducing the pressure to the vacuum degree of-0.06-0.09 MPa, heating to 44 ℃ for reacting for 3h, adding deionized water after the reaction, controlling the temperature to 22 ℃ and dropwise adding 30% hydrochloric acid solution, controlling the pH value of the system to be 1-2, centrifuging, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; the centrifugally separated liquid enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for an acidification process by adjusting the concentration, and the evaporated liquid is used for absorbing the hydrogen chloride gas generated in the step (1) by adjusting the concentration.
The purity of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in this example was 96.51%, and the yield was 92.15%.
Comparative example 1
An environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle under the protection of nitrogen, cooling to the temperature of-7 ℃, then introducing chlorine, controlling the temperature to 5 ℃, controlling the temperature to 18h, after introducing chlorine, heating to 20 ℃ and reacting for 3.2h, after the reaction is finished, introducing residual hydrogen chloride gas removed by nitrogen, absorbing the residual hydrogen chloride gas by brine, then heating and evaporating the residual hydrogen chloride gas in an evaporation tower to obtain hydrogen chloride gas, absorbing the hydrogen chloride gas by a water absorption tower, adjusting the concentration of the hydrogen chloride gas for a subsequent acidification process, and recycling the evaporated brine for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration of the evaporated brine;
(2) And (3) ring closure: under the protection of nitrogen, pumping acetonitrile into a closed loop kettle, adding solid sodium hydroxide through a solid feeder, starting stirring, controlling the temperature to 22 ℃ and adding thioacetamide, controlling the temperature to 25 ℃ and dropwise adding ethyl chlorotrifluoroacetoacetate through a metering tank, controlling the temperature to 20 ℃ after 3.8 hours, reacting for 3 hours, then dropwise adding triethylamine, controlling the temperature to 1.5 hours, heating to 76 ℃ after the dropwise adding is finished, refluxing for 3.2 hours, cooling the reaction solution to below 25 ℃, filtering triethylamine hydrochloride, decompressing and distilling filtrate to obtain acetonitrile and triethylamine, and then introducing the acetonitrile and triethylamine into a closed loop liquid metering tank; adding the filtered triethylamine hydrochloride into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer for use as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated; the acetonitrile and triethylamine distilled under reduced pressure are reused for the cyclization reaction of the step (2);
(3) Alkaline hydrolysis and acidification: preparing 55% sodium hydroxide solution in a saponification kettle, controlling the molar ratio of ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution to be 1:1.6:0.2:1.07:2.4:1.9, cooling to 20 ℃, dropwise adding a closed-loop solution metering tank filtrate, controlling the dropwise adding to 3.2h, reducing the pressure to the vacuum degree of-0.06-0.09 MPa, heating to 44 ℃ for reacting for 3h, adding deionized water after the reaction, controlling the temperature to 22 ℃ and dropwise adding 30% hydrochloric acid solution, controlling the pH value of the system to be 1-2, centrifuging, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; the centrifugally separated liquid enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for an acidification process by adjusting the concentration, and the evaporated liquid is used for absorbing the hydrogen chloride gas generated in the step (1) by adjusting the concentration.
The purity of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in this example was 92.62%, and the yield was 85.09%.
Comparative example 2
An environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which comprises the following steps:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle under the protection of nitrogen, cooling to the temperature of-7 ℃, then introducing chlorine, controlling the temperature to 5 ℃, controlling the temperature to be 18 hours, heating to the temperature of 20 ℃ after introducing the chlorine, reacting for 3.2 hours, arranging an absorption chamber in the chlorination kettle, storing salt water in the absorption chamber for absorbing hydrogen chloride gas generated in the reaction process, and introducing nitrogen to remove residual hydrogen chloride gas and a small amount of chlorine in the reaction liquid after the reaction is completed, so as to obtain ethyl chlorotrifluoroacetoacetate; residual hydrogen chloride gas removed by nitrogen is absorbed by brine and then is put into an evaporation tower together with the brine absorbed by the hydrogen chloride gas in an absorption chamber to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for a subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration;
(2) And (3) ring closure: under the protection of nitrogen, pumping acetonitrile into a closed loop kettle, adding solid sodium hydroxide through a solid feeder, starting stirring, controlling the temperature to 22 ℃ and adding thioacetamide, controlling the temperature to 25 ℃ and dropwise adding ethyl chlorotrifluoroacetoacetate through a metering tank, controlling the temperature to 20 ℃ after 3.8 hours, reacting for 3 hours, then dropwise adding triethylamine, controlling the temperature to 1.5 hours, heating to 76 ℃ after the dropwise adding is finished, refluxing for 3.2 hours, cooling the reaction solution to below 25 ℃, filtering triethylamine hydrochloride, decompressing and distilling filtrate to obtain acetonitrile and triethylamine, and then introducing the acetonitrile and triethylamine into a closed loop liquid metering tank; adding the filtered triethylamine hydrochloride into a sodium hydroxide solution, stirring, standing, layering, and recovering triethylamine from the upper layer for use as an acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated; the acetonitrile and triethylamine distilled under reduced pressure are reused for the cyclization reaction of the step (2);
(3) Alkaline hydrolysis and acidification: preparing 55% sodium hydroxide solution in a saponification kettle, controlling the molar ratio of ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution to be 1:1.6:0.2:1.07:2.4:1.9, cooling to 20 ℃, dropwise adding a closed-loop solution metering tank filtrate, controlling the temperature to be 3.2h after dropwise adding, heating to 44 ℃ for reaction for 3h, cooling to 22 ℃ after the reaction is finished, decompressing and heating to 44 ℃ for removing ethanol, adding deionized water, controlling the temperature to 22 ℃ and dropwise adding 30% hydrochloric acid solution, controlling the pH value of a system to be 1-2, centrifugally separating, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid; the centrifugally separated liquid enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for an acidification process by adjusting the concentration, and the evaporated liquid is used for absorbing the hydrogen chloride gas generated in the step (1) by adjusting the concentration.
The purity of 2-methyl-4-trifluoromethyl-5-thiazolecarboxylic acid prepared in this example was 91.89%, and the yield was 84.97%.
The present invention is not limited to the above embodiments, but is capable of modification and variation in detail, and other modifications and variations can be made by those skilled in the art without departing from the scope of the present invention.
Claims (10)
1. The environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid is characterized by comprising the following steps of:
(1) Chlorination: pumping ethyl trifluoroacetoacetate into a chlorination kettle by a pump under the protection of nitrogen, cooling, introducing chlorine, controlling the temperature, heating to react after introducing the chlorine, and finally introducing nitrogen to expel hydrogen chloride gas in the reaction liquid to obtain ethyl chlorotrifluoroacetoacetate;
(2) And (3) ring closure: under the protection of nitrogen, acetonitrile is pumped into a closed loop kettle by a pump, solid sodium hydroxide is added through a solid feeder, stirring is started, temperature is controlled, thioacetamide is added, ethyl chlorotrifluoroacetoacetate is dripped through a metering tank, temperature is controlled after dripping is finished, triethylamine is dripped, heating reflux reaction is carried out after dripping is finished, triethylamine hydrochloride is filtered after the reaction liquid is cooled, and acetonitrile and triethylamine are distilled out from filtrate under reduced pressure and then are led into a closed loop liquid metering tank;
(3) Alkaline hydrolysis and acidification: preparing sodium hydroxide solution in a saponification kettle, cooling, then dropwise adding a closed-loop liquid metering tank filtrate, reducing pressure, heating for reaction, adding deionized water after the reaction is completed, controlling the temperature, dropwise adding a hydrochloric acid solution, centrifugally separating, leaching and drying to obtain 2-methyl-4-trifluoromethyl-5-thiazole formic acid.
2. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein the cooling temperature in the step (1) is-3 to-7 ℃; the temperature control means controlling the temperature to be 5-10 ℃; the chlorine is introduced for 18-22 hours; the heating is to heat to 20-25 ℃; the reaction time is 2.8-3.2h.
3. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein in the reaction process of the step (1), an absorption chamber is arranged in a chlorination reactor, and brine is stored in the absorption chamber for absorbing hydrogen chloride gas generated in the reaction process; and (3) introducing nitrogen to remove the hydrogen chloride gas in the reaction liquid, and then absorbing the hydrogen chloride gas by using saline.
4. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid according to claim 3, wherein the brine after absorbing the hydrogen chloride gas enters an evaporation tower to be heated and evaporated to obtain the hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is used for the subsequent acidification process by adjusting the concentration, and the evaporated brine is reused for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration.
5. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein the temperature in the step (2) is controlled to be 20-25 ℃ by adding thioacetamide; controlling the temperature and dropwise adding ethyl chlorotrifluoroacetoacetate into a metering tank to control the temperature to 15-25 ℃; the dropwise adding of the chloro-trifluoro-acetoacetic acid ethyl ester is completed after 3-4 hours of dropwise adding; the temperature control reaction after the completion of the dripping is that the reaction is carried out for 2.8 to 3.2 hours at the temperature of 20 to 25 ℃; the dripping triethylamine is controlled to be 1.5-2 hours after the dripping is finished; the thermal reflux reaction is reflux reaction for 2.8-3.2h at 76-78 ℃; the cooling of the reaction liquid means cooling to below 25 ℃.
6. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein the triethylamine hydrochloride filtered in the step (2) is put into sodium hydroxide solution, stirred, stood still and layered, and triethylamine is recovered from the upper layer for being used as the acid binding agent in the step (2); the lower layer is the mixed solution of sodium chloride and sodium hydroxide, and the mixed solution is reused for absorbing the hydrogen chloride gas generated in the step (1) after the concentration is regulated.
7. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein acetonitrile and triethylamine distilled off under reduced pressure in the step (2) are reused for the cyclization reaction in the step (2).
8. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole carboxylic acid according to claim 1, wherein the mass concentration of the sodium hydroxide solution in the step (3) is 45-55%; the cooling refers to cooling to 20-25 ℃; the filtrate of the dripping closed-loop liquid metering tank is controlled to be 2.8-3.2 hours after the dripping is finished; the decompression and temperature rising reaction means that the vacuum degree is controlled to be-0.06 to-0.09 MPa, the reaction temperature is controlled to be 43-45 ℃, and the reaction time is controlled to be 2.8-3.2 hours; the temperature control means controlling the temperature to be 20-25 ℃; the mass concentration of the hydrochloric acid solution is 30-35%; the drop adding amount of the hydrochloric acid solution controls the pH value of the system to be 1-2.
9. The green environmental protection process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid according to claim 1, wherein the centrifugally separated liquid in the step (3) enters an evaporation tower to be heated and evaporated to obtain hydrogen chloride gas, the hydrogen chloride gas is absorbed by a water absorption tower and then is recycled for an acidification process by adjusting the concentration, and the evaporated liquid is recycled for absorbing the hydrogen chloride gas generated in the step (1) after adjusting the concentration.
10. The green and environment-friendly process for synthesizing 2-methyl-4-trifluoromethyl-5-thiazole formic acid, which is characterized in that the molar ratio of the addition amount of ethyl trifluoroacetoacetate, chlorine, solid sodium hydroxide, thioacetamide, triethylamine and sodium hydroxide solution in the synthesis process of 2-methyl-4-trifluoromethyl-5-thiazole formic acid is 1:1.2-1.6:0.1-0.2:1.06-1.08:1.8-2.4:1.9-2.5.
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