CN1944376A - Method for purifying perfluoro caprylic acid - Google Patents
Method for purifying perfluoro caprylic acid Download PDFInfo
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- CN1944376A CN1944376A CN 200610022023 CN200610022023A CN1944376A CN 1944376 A CN1944376 A CN 1944376A CN 200610022023 CN200610022023 CN 200610022023 CN 200610022023 A CN200610022023 A CN 200610022023A CN 1944376 A CN1944376 A CN 1944376A
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- perfluorocaprylic acid
- perfluorocaprylic
- perfluoro caprylic
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Abstract
The present invention discloses method of purifying crude perfluoro caprylic acid product during electrolytic fluorination process to prepare perfluoro caprylic acid. Into crude perfluoro caprylic acid product obtained through hydrolyzing and sulfuric acid acidifying separated precipitant from electrolyte after electrolytic fluorination, proper amount of hydrogen peroxide is added to oxidize impurities containing -OH and -Cl radicals into carboxylic acid, and the mother liquid is separated after stilling, washed with deionized water, added with sulfuric acid to pH 4-5, let stilling to eliminate washing medium water and distilled to obtain perfluoro caprylic acid product. The method treats the main impurities Rf1-CFCl-Rf2 and Rf1-CFOH-Rf2 into low carbon fatty acid easy to separate.
Description
Technical field
The present invention relates to a kind ofly be equipped with in the Perfluorocaprylic Acid production technique in the electrofluorination legal system, the method that the Perfluorocaprylic Acid runic is purified, exactly, be with strong oxidizer impurity in the oxidation Perfluorocaprylic Acid runic at ambient temperature, thereby obtain the method for the high Perfluorocaprylic Acid product of purity.
Background technology
Perfluorocaprylic Acid is the main raw material of tetrafluoroethylene letex polymerization with the dispersion agent ammonium perfluorocaprylate, usually prepare Perfluorocaprylic Acid with the capryl(yl)chloride for the raw material electrofluorination, EO obtains electrolytic solution in the electrofluorination process, behind hydrolysis, sulfuric acid acidation, obtain the Perfluorocaprylic Acid runic, obtain the Perfluorocaprylic Acid product through fractionation by distillation again.Wherein, in the Perfluorocaprylic Acid runic, contain Perfluorocaprylic Acid, impurity: hydrofluoric acid, hydrochloric acid, silver fluoride, Rf1-CFCl-Rf2, Rf1-CFOH-Rf2, the organic high boiling material of perfluor (fluorine-containing), low-boiling-point substance etc.
With behind this Perfluorocaprylic Acid runic purifying as the ammonium perfluorocaprylate of feedstock production-as tetrafluoroethylene letex polymerization dispersion agent, as tetrafluoroethylene monomer polymerization system PTFE dispersion resin, adopt the dispersion polymerization system of ammonium persulfate-sodium bisulfite, 15～80 ℃ of temperature of reaction, when using ammonium perfluorocaprylate as dispersion agent, impurity in the Perfluorocaprylic Acid is to speed of response, polymerization pre-induction phase length is extremely responsive, be embodied in: polymerization is long inductive phase in early stage, polymeric chain rise period speed of response is slow, and chain termination in advance, cause polymer fluid concentration low, the poor performance of resin post-treatment, standard specific gravity is higher, and molecular-weight average is low.
The reason of searching to the bottom: Perfluorocaprylic Acid is in preparation process, exist and contain-OH (hydroxyl), the impurity of-Cl (halogenide) group, the reason that this class impurity produces mainly is: the main raw material capryl(yl)chloride of Perfluorocaprylic Acid, in the electrofluorination process, fluoridize not exclusively, bring Rf1-CFCl-Rf2 (Rf1 in the product, Rf2 refers to perfluor (fluorine-containing) aliphatic hydrocarbon of carbon atom 0～6) material, the easy hydrolysis of Rf1-CFCl-Rf2 simultaneously obtains Rf1-CFOH-Rf2, Perfluorocaprylic Acid contains above-mentioned impurity, boiling point and Perfluorocaprylic Acid boiling point are relatively near (carbonatoms is identical, alcohol, halogenide, the boiling point difference of carboxylic acid is less), be difficult to separate at still-process, bring into simultaneously in the Perfluorocaprylic Acid product at the temperature section of collecting Perfluorocaprylic Acid (distillation under 85～115 ℃ of vacuum conditions).This class impurity is introduced in the tetrafluoroethylene emulsion polymerization process, in the oxidation-reduction polymerization system that ammonium persulfate-sodium bisulfite causes, can play the termination of chainpropagation.
Generally speaking,, comprise common and documents and materials introduce, mainly contain the Perfluorocaprylic Acid purification treating method:
1) use the chloroform give solvent, circulation crystallization and purification, advantage can obtain high-purity Perfluorocaprylic Acid of content 〉=99.5% (wt), but its introduces the organic chloride-trichloromethane play chain transfer in the TFE dispersion polymerization process and other;
2) the ammoniacal liquor salinization is refining, obtains the salts solution of Perfluorocaprylic Acid and homologue thereof, separates other inorganic salts (solid) impurity wherein.Need sulfuric acid acidation to separate Perfluorocaprylic Acid simultaneously, introduce new impurity, produce a large amount of waste liquids.Use has considerable influence to PTFE resin polymerization process as the TFE dispersion agent;
3) sulfuric acid oxidation (acidifying) is handled, mainly can separation of organic substances and inorganics, obtain Perfluorocaprylic Acid after the processing as TFE polymeric emulsifiers raw material, fail effectively to remove contain-OH (hydroxyl) ,-impurity of Cl (halogenide) group, use has limitation, and PTFE resin polymerization process is had considerable influence;
4) dichromic acid high temperature oxidation, dichromate need reclaim, and environmental protection investments are big, and dichromate is to surface water pollution, and is big to PTFE output capacity and quality fluctuation in the TFE polymerization process.
5) use the ammonium persulphate oxidation, obtaining Perfluorocaprylic Acid (itself remaining in the TFE polymerization as initiator) directly influences TFE polymeric speed of response and PTFE resin quality.
In sum, existing in the Perfluorocaprylic Acid purification treating method, do not remove effectively contain-OH (hydroxyl) ,-impurity of Cl (halogenide) group, cause these impurity to be brought in the PTFE polymerization process, thereby produce the disadvantageous various influences of polymerization.
Summary of the invention
The objective of the invention is to overcome the shortcoming of above-mentioned prior art and provide a kind of the Perfluorocaprylic Acid purification treating method, this method can effectively remove containing in the Perfluorocaprylic Acid-OH (hydroxyl) ,-impurity of Cl (halogenide) group, improve the purity of Perfluorocaprylic Acid.
The object of the present invention is achieved like this:
Consider in the Perfluorocaprylic Acid runic to contain-OH (hydroxyl) ,-impurity of Cl (halogenide) group, just the boiling point of these impurity and Perfluorocaprylic Acid near and be difficult to remove by distillation, therefore must find a kind of auxiliary agent that can remove these impurity and not influence the Perfluorocaprylic Acid that obtains high polymerization-grade, and this auxiliary agent can not be brought new impurity into, through experiment screening repeatedly, found following technical scheme:
Adopting sulfuric acid acidation, distillation to collect in the prior art of Perfluorocaprylic Acid, increasing the employing hydrogen peroxide and carry out oxide treatment Perfluorocaprylic Acid runic and clean the mother liquor step, be specially:
Obtain electrolytic solution with the capryl(yl)chloride for the raw material electrofluorination, after isolating throw out, hydrolysis, sulfuric acid acidation obtain the Perfluorocaprylic Acid runic, in the Perfluorocaprylic Acid runic, add again an amount of hydrogen peroxide will wherein contain-OH and-impurity oxygen of Cl group changes into carboxylic acid, isolate mother liquor after leaving standstill, use the washed with de-ionized water mother liquor again, adding sulfuric acid control mother liquor pH value is 4～5, after standing separation goes out cleaning medium water, the mother liquor distillation of cleaning is obtained the Perfluorocaprylic Acid product.
Wherein, the weight of the hydrogen peroxide that adds preferably be controlled at be equivalent to Perfluorocaprylic Acid runic weight 5～35% between, this not only can guarantee effectively to remove contain-OH (hydroxyl) ,-impurity of Cl (halogenide) group, follow-up washed with de-ionized water step is more prone to.
For the quality that guarantees to clean, the step of repeated using deionized water and sulfuric acid scrubbing mother liquor repeatedly, generally speaking, triplicate is go out to be present in waste water in the mother liquor and an excessive hydrogen peroxide capable of washing.
The strong oxidizer that the present invention uses-hydrogen peroxide oxidation is handled the Perfluorocaprylic Acid runic, mainly Rf1-CFCl-Rf2, Rf1-CFOH-Rf2 impurity are processed into low-carbon (LC) straight chain type perfluor low carbon fatty acid, because low-carbon (LC), what form is low-boiling-point substance, therefore their boiling points and Perfluorocaprylic Acid differ distant, very easily effectively separate in follow-up still-process.Reaction mechanism is, impurity-the OH that contains (hydroxyl) ,-Cl (halogenide) group, oxidisability general-OH by hydrogen peroxide is oxidized to-COOH (carboxyl), generating product is perfluor low-carbon (LC) carboxylic acid, oxidisability general-Cl by hydrogen peroxide is oxidized to hypochlorous acid, generate product band-OH, the oxidation step of going forward side by side becomes perfluor low-carbon (LC) carboxylic acid, remove these perfluor low-carbon (LC) carboxylic acids by distillation, thereby can effectively avoid containing-OH and-impurity of Cl influences the chain termination in the TFE polymerization process, the TFE polymerization can normally be reacted, guarantee the polymerization quality.
Description of drawings
Fig. 1 is a process flow sheet of the present invention.
Embodiment
Below in conjunction with drawings and Examples the present invention is described in further details, but following example is not a limiting the scope of the invention:
Embodiment 1: handle, oven dry, electrolyzer after the activation, use inert gas replacement, add 100 parts of (weight part) capryl(yl)chlorides, heat up 75～100 ℃, add hydrofluoric acid (gas phase) 300～350 parts under the control condition continuously, pressure-fired is fluoridized, 82 ± 2 ℃ of controlled temperature, reaction times control 12～15 hours, reaction finishes the back inert gas replacement, find time to fill nitrogen, logical atmosphere is emitted and is fluoridized electrolytic solution, in fluoridizing electrolytic solution, add deionized water then continuously, stir, put to whizzer and dry only control PH ≈ 6, solid slag needs environmental protection treatment, washing can be removed hydrofluoric acid, hydrochloric acid, solid inorganic salt such as silver chloride, silver fluoride, iron protochlorides etc. add an amount of sulfuric acid Perfluorocaprylic Acid then in clear liquid, perfluor (fluorine-containing) organic alcohols, perfluor (fluorine-containing) halogenated organic hydrocarbon and water medium layering obtain the Perfluorocaprylic Acid runic.
Get Perfluorocaprylic Acid runic 20～50kg, 15～35 ℃ of temperature, agitation condition slowly adds 2.5～7kg hydrogen peroxide down, the weight content of hydrogen peroxide is 30～35% all can, stirred 20～30 minutes, left standstill 5～7 hours, and added hydrogen peroxide and mainly Rf1-CFCl-Rf2, Rf1-CFOH-Rf2 impurity are processed into low-carbon (LC) straight chain type perfluor low carbon fatty acid; Isolate the upper strata mother liquor, clean to be equivalent to 1: 1 volume ratio of mother liquor adding deionized water again, stirred 10～15 minutes, add an amount of sulfuric acid Perfluorocaprylic Acid and water medium layering, control solution PH 4～5 left standstill 10 minutes, isolate and clean top dielectric water, clean so repeatedly three times.Perfluorocaprylic Acid mother liquor through cleaning, in distillation tower, the step-down distillation, working pressure 0.005MPa collects 83～107 ℃ cut, promptly gets the product Perfluorocaprylic Acid, and front-end volatiles are low-boiling-point substance below 83 ℃, remain the height raffinate that boils and make environmental protection treatment.
Claims (3)
1, a kind of method of purification of Perfluorocaprylic Acid, be to obtain electrolytic solution for the raw material electrofluorination with the capryl(yl)chloride, after isolating throw out, hydrolysis, sulfuric acid acidation obtain the Perfluorocaprylic Acid runic, it is characterized in that again in the Perfluorocaprylic Acid runic, adding an amount of hydrogen peroxide will wherein contain-OH and-impurity oxygen of Cl group changes into carboxylic acid, isolate mother liquor after leaving standstill, use the washed with de-ionized water mother liquor again, adding sulfuric acid control mother liquor pH value is 4～5, after standing separation goes out cleaning medium water, the mother liquor distillation of cleaning is obtained the Perfluorocaprylic Acid product.
2, method of purification according to claim 1, the weight that it is characterized in that adding hydrogen peroxide is 5～35% of Perfluorocaprylic Acid runic weight.
3, method of purification according to claim 1, the volume that it is characterized in that adding the deionized water that cleans mother liquor is identical with the volume of mother liquor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CNB2006100220238A CN100393690C (en) | 2006-10-10 | 2006-10-10 | Method for purifying perfluoro caprylic acid |
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| CNB2006100220238A CN100393690C (en) | 2006-10-10 | 2006-10-10 | Method for purifying perfluoro caprylic acid |
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| CN1944376A true CN1944376A (en) | 2007-04-11 |
| CN100393690C CN100393690C (en) | 2008-06-11 |
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| CNB2006100220238A Expired - Fee Related CN100393690C (en) | 2006-10-10 | 2006-10-10 | Method for purifying perfluoro caprylic acid |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101397245A (en) * | 2007-09-26 | 2009-04-01 | 上海富诺林精细化工有限公司 | Method for purifying perflurooctanoic acid |
| CN103420836A (en) * | 2012-05-21 | 2013-12-04 | 上海品沃化工有限公司 | Purifying method of fluorine-containing low-carbon aliphatic acid |
| CN103570202A (en) * | 2013-11-04 | 2014-02-12 | 中昊晨光化工研究院有限公司 | Method and device for recovering electrolytic residues produced in process of producing perfluorocaprylic acid by electrolytic process |
| CN112028765A (en) * | 2020-08-31 | 2020-12-04 | 上海沃凯生物技术有限公司 | Separation method of mixture of linear perfluorooctanoic acid and branched perfluorooctanoic acid |
| CN114989007A (en) * | 2022-05-27 | 2022-09-02 | 山东东岳高分子材料有限公司 | Method for controlling purity of perfluorooctanoic acid |
| CN115417758A (en) * | 2022-09-22 | 2022-12-02 | 山东大学 | Preparation method of high-purity crystalline perfluorooctanoic acid |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0794401B2 (en) * | 1987-10-30 | 1995-10-11 | 株式会社トーケムプロダクツ | Method for separating n-perfluorooctanoic acid |
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2006
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101397245A (en) * | 2007-09-26 | 2009-04-01 | 上海富诺林精细化工有限公司 | Method for purifying perflurooctanoic acid |
| CN101397245B (en) * | 2007-09-26 | 2013-11-06 | 上海富诺林精细化工有限公司 | Method for purifying perflurooctanoic acid |
| CN103420836A (en) * | 2012-05-21 | 2013-12-04 | 上海品沃化工有限公司 | Purifying method of fluorine-containing low-carbon aliphatic acid |
| CN103570202A (en) * | 2013-11-04 | 2014-02-12 | 中昊晨光化工研究院有限公司 | Method and device for recovering electrolytic residues produced in process of producing perfluorocaprylic acid by electrolytic process |
| CN103570202B (en) * | 2013-11-04 | 2014-12-24 | 中昊晨光化工研究院有限公司 | Method and device for recovering electrolytic residues produced in process of producing perfluorocaprylic acid by electrolytic process |
| CN112028765A (en) * | 2020-08-31 | 2020-12-04 | 上海沃凯生物技术有限公司 | Separation method of mixture of linear perfluorooctanoic acid and branched perfluorooctanoic acid |
| CN112028765B (en) * | 2020-08-31 | 2022-12-13 | 上海沃凯生物技术有限公司 | Separation method of mixture of linear perfluorooctanoic acid and branched perfluorooctanoic acid |
| CN114989007A (en) * | 2022-05-27 | 2022-09-02 | 山东东岳高分子材料有限公司 | Method for controlling purity of perfluorooctanoic acid |
| CN115417758A (en) * | 2022-09-22 | 2022-12-02 | 山东大学 | Preparation method of high-purity crystalline perfluorooctanoic acid |
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| CN100393690C (en) | 2008-06-11 |
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Address after: 643201 Zigong County, Sichuan Province, Chenguang Road, No. 135, Fushun Patentee after: Zhonghao Chenguang Chemical Institute Co., Ltd. Address before: 643201, Chenguang Road, Fu town, Fushun County, Zigong, Sichuan, 135 Patentee before: Zhonghao Chenguang Chemical Research Inst. |
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Granted publication date: 20080611 Termination date: 20181010 |