Patented May 2, 1950 2,506,068

UNITED STATES PATENT OFFICE 2,506,068 * PRODUCTION OF FLUOROACETIC ACDS i.John W. C. Crawford, Welwyn Garden City, and Eric. R. Wallsgrove, Leamington Spa, England, ..assignors to imperial Chemical Industries Lim ited, a corporation of Great Britain 'i No Drawing. 3 Application February 10, 1948, Se ; :rial No. 7,522. In Great Britain, February 17, 94 11. Claims, (C.260-539) 2 This invention, relates to the production of the necessary alkali is provided by the -alkali fluoroacetic acids, esters and salts thereof, and metal hydroxides. Fluoroacetic acids - may be more particularly to the production of di- and obtained by acidifying mixtures obtained after trifluoroacetic acids; and esters and Salts thereof. this reacticn (or fractions of these mixtures). British Patent No. 577,481 describes a process Fluoroethylenic compounds in which Z is CF2X for the production of fluoroacetic acids and al are particularly preferred as these give a yield kali metal salts' thereof: comprising.; reacting per mol of twice that of the other fluoroethylenic,2 compounds of the type fluoroethylenic compounds used, as starting ima ...CFXCYCYZ. terials in the process of this invention. it) Suitable starting materials which may be used -in which Yland; Zare hydrogenior: chlorine and in carrying out the process of our invention in X is hydrogen, fiuorine or chlorine, with an: al clude 3,3,3-trifiuoro-1,1,2, trichloro-propene-1 kali metal permanganate in alkaliraer. Faedium. CF3-CCi=CC2, 3,3-difluoro-1,1,2,3-tetrachloro : This process suffers: from the disadvantage that propene-1,... CClF2-CCl=CCl2 and 1,1,1,4,4,4- it cannot be accomplished satisfactorily in stain hexafluoro-2,3-dichloro-butadiene-2, less"steel-pots: as these pots are attacked by hot alkaline permanganate:Solutions. . It cannot be accomplished in enamel-lined spots, e.g. Pfaudler hydroxide is preferred on account of its pots; either, if strong-caustic: alkali-solutions-are availability and cost and because, if any perman in used as these solutions attack-the-linings-of-these ; ganate remains in the reaction mixture at the spots. If, however, the reaction is accomplished Competition of the reaction, this is destroyed in the presence of a small aimount of alkali, car easily by passing sulphur dioxide, di gbon dioxide is liberated; during the reaction and ... oxide and calcium sulphate being precipitated ...this carries some fluoroacetic acid from the: re from Solutions containing . saction, mixture; and processing complications; or 2.5 "Any salts of may be used in loss of yield result. the process of this invention. Potassium per ... It has also been proposed to produce trifluoro manganate is preferred as it is available and by the chronic-acid oxidation of in 'cheap. The use of calcium permanganate in aminobenzotrifluoride. This latter process, how conjunction. With calcium-hydroxide and with the ever, has the disadvantage. Of-being slow, costly, 3. use of sulphur dioxide to destroy the excess per ... giving... only yields-of-the order of 55-60%, and manganate gives solutions of salts of fluoroacetic presenting major corresion problems. acids which are contaminated only with calcium ... An object of this invention is to provide-means chloride. for the production of fluoroacetic acids, esters The permanganate salt- may be used in the and salts thereof by a process suitable for use in s'& 2). theoretical amount or in slight excess and may *ename lined vessels: 5Another object is to pro be, for example in the form of a 5% to 25% aque vide an economic means for the production of ous solution and of these the more concentrated fluoroacetic acids, esters and Salts thereof. A "Solutions are preferred because less water has to further object is to provide means for the pro "he removed subsequently. C duction of fluoroacetic acids, esters and salts 4; In general, temperatures of the Order of 70° C. thereof by a process giving greater yields, and to 80°C. are satisfactory for carrying out the rtaking less time than heretofore.'. Other objects process of this invention although a wider range will appear hereinafter. of temperatures may be employed, for example, ; : According to the present invention these oh temperatures ranging from 20° C. to 130° C. In ijects are accomplished by a process comprising 5 general, the process, may be carried out at atmos the step of reacting a fluoroethylenic"compound pheric pressure, although, higher or lower pres : of the type CFXCYg CYZin which X is hydro Sures may be employed if desired. When ten gen, fluorine or, chlorine Y is hydrogen or chio peratures above 100° C. are employed, pressure *::rine, and Z, is hydrogen, chlorine or CSX, with vessels may be used, and the permanganate and l, an aqueous' permanganate solution in the pres alkali nay be added simultaneously and slowly to rence of sufficient calcium and/or magnesium ox the higher boiling organic start-materials. An ide oir hydroxide to combine with all acids liber ''' alternative procedure which is preferable in some 2.3ated by the reaction. These reaction mixtures cases is to add the organic compound to an agi : have a low alkalifity and the enamelled glass tated solution containing-permanganate and al lined vessels are not attacked, as is the case where 5.5-kali. 2,506,068 3 4 In one form of the invention the fluoroethylenic The was dissolved in compound is charged into a reaction vessel, with the Water and fed into the reaction vessel to water, calcium or potassium permanganate and gether with the . The trichloro sufficient line to ensure that the reaction mixture trifluoropropene was added to the well-stirred so remains alkaline throughout the reaction. The 5 lution at 65-70° C. Over a period of 9 hours. After mixture is heated with agitation, the temperature completion of the addition, the Solution was being raised sufficiently to produce smooth reac gradually heated up to 95° C. until no further tion. refluxing took place. After cooling, the solution When the reaction has been completed any un was decolourised by addition of sodium bisulphite reacted fluoroethylenic compound may be dis O and the precipitated , calcium tilled off. If there is present excess of perman sulphate and calcium carbonate were filtered off. ganate, it may be destroyed by reaction with a The filtrate was treated with strong potassium reagent such as Sulphur dioxide, hydrogen perOX carbonate Solution until no more calcium carbon ide, sodium sulphite, sodium bisulphite or SO ate was precipitated. After filtration, the Solu dium hydrosulphite. The salt of the fluoroacetic tion was evaporated to dryness and extracted acid may be isolated admixed with calcium chlo with methanol, giving 27 parts (89% yield) of ride and potassium chloride, if potassium per potassium trifiuoroacetate. manganate is used, from the reaction mixture by filtration to remove manganese dioxide, calciun Eacample II sulphate, calcium carbonate and any unreacted 20 95 parts of trifluorotrichloropropene were oxi lime, and evaporation to dryness. An alternative dised as in Example 1. method of isolating salts other than those of the 136 parts of crude dry solid were obtained by alkaline earth metals is to treat the reaction mix evaporation. 47 parts of this solid were treated ture with a water-soluble carbonate, such as So with 32 parts of concentrated sulphuric acid dium or potassium carbonate, and filter off the 25 which was added gradually. When all the acid solution of the crude salt from precipitated cal had been added, the mixture was heated and the cium carbonate. If desired, the filtered reaction trifluoroacetic acid distilled off as it was formed. mixture may be treated with the theoretical The crude product was redistilled and 9 parts of amount of an excess of Sulphuric acid to set free trifluoroacetic acid, B. P. 71.5-72.5° C., contain the fluoroacetic acid, the aqueous fluoroacetic 30 ing less than 0.03% hydrochloric acid were ob acid distilled off, neutralised with sodium car tained. - bonate and dried as the sodium Salt, Which may We claim: be mixed with the theoretical amount or an ex 1. A process for the production of potassium cess of sulphuric acid (suitably of 93% to 100% trifluoroacetate which comprises reacting tri strength), and the fluoroacetic acid recovered by 35 fluoro trichloro propene at a temperature of distillation. 65-70° C. at atmospheric pressure with an acque Alternatively the acid may be obtained from ous potassium permanganate solution of 5-25%, the neutralised reaction mixture, which may have concentration in the presence of sufficient cal been treated with a soluble carbonate, if desired, cium hydroxide to combine with all of the acids by evaporation followed by extraction of the flu 40 Oroacetates with an organic solvent, evaporation liberated during the reaction, cooling the reaction of the organic solvent, treatment with the the mixture. decolorizing the mixture by addition of oretical quantity or an excess of Sulphuric acid sodium bisulfite, filtering the solution, treating and distillation of the pure fluoroacetic acid. the filtrate with potassium carbonate until cal Any Organic Solvent which is inert to the ingredi cium carbonate ceases to be precipitated, filtering ents of the reaction mass and which dissolves the the resulting mixture, evaporating the filtrate to desired product but not the undesired products dryness and extracting the dry mass with alco Such as the halide salts, may be used. Examples hol, whereby potassium trifluoroacetate is ob of satisfactory solvents are methyl alcohol, ethyl tained. alcohol, isopropyl alcohol, secondary butyl alco 2. A process for the production of a fluoro hol, , acetone, dioxane and ethyl ace acetyl compound which comprises the step of re tate. acting a fluoroethylenic compound from the group Esters are prepared from the salts and acids consisting of those having the general formulae: produced by the process of this invention by any CF2XCY=CYZ and CFXYC-CYCFX of the conventional methods for example direct wherein X is a radical from the group consisting esterification, ester interchange and the like. of hydrogen, fluorine and chlorine, and Y and Z Thus in one method of preparing esters of any are radicals from the group consisting of hydro excess of permanganate in the oxidised reaction gen and chlorine, with an acueous metal per mixture is destroyed, the precipitated manganese manganate Solution, in the presence of an amount dioxide filtered off and the filtrate evaporated to 30 of a basic compound from the group consisting of dryneSS, Sulphuric acid and the alcohol to be es calcium and magnesium oxide and hvdroxide suf terified added and the ester recovered by distilla ficient to combine with all the acids liberated dur tion. ing the reaction, and separating the resulting The following examples in which all parts are fluoroacetyl compound from the reaction mixture. by weight, except where otherwise stated illus 65 3. A process as claimed in claim 2 wherein the trate the process of this invention but it is to be adueous metal permanganate solution is of understood that the invention is in no way lim 5-25% by weight concentration. ited by the examples. 4. A process as claimed in claim 2 wherein the permanganate solution is an adueous potassium Eacample I O permanganate solution of 5-25% by weight con Parts centration. 3,3,3-trifluoro-1,1,2 trichloropropene-1------40 5. A process as claimed in claim 2 wherein said Calcium hydroxide------27 reaction is carried out at a temperature between Potassium permanganate------46 20 and 130° C. Water ------300 75 6. A process as claimed in claim 5 wherein said 2,506,068 5 6 reaction is carried out at a temperature of wherein X is a radical from the group consisting 70-80° C. of hydrogen, fluorine and chlorine, and Y and Z. 7. A process as claimed in claim 2 wherein said are radicals from the group consisting of hydro reaction is carried out at atmospheric pressure. gen and chlorine, with an aqueous metal perman 8. A proceSS as claimed in claim 2 wherein said ganate Solution, in the presence of an amount of reaction is carried out under super-atmospheric a basic compound from the group consisting of preSSure and at a temperature greater than 100 calcium and magnesium oxide and hydroxide re C. quired to combine with all the acids liberated dur 9. A process as claimed in claim 2 wherein ing the reaction, and separating the resulting Separation of the fluoroacetyl compound is ac O fluoroacetyl compound from the reaction mixture. complished by treating the reaction mixture with JOHN W. C. CRAWFORD, a Soluble carbonate, filtering, evaporating the fil ERIC. R. WALLSGROWE. trate to dryneSS, extracting the fluoroacetates With an Organic Solvent and evaporating the REFERENCES CITED Solvent. The following references are of record in the 10. A proceSS as claimed in claim 2 wherein the file of this patent: fluoroethylenic compound is selected from the group consisting of 3,3,3-trifluoro-1,2-trichloro UNITED STATES PATENTS propene-1; 3,3-difluoro - ,1,2,3-tetrachloro-pro Number Name Date pene-1 and 1,1,1,4,4,4-hexafluoro - 2,3 - dichloro- 0 2371757 Henne ------Mar. 20, 1945 butene-2. 2,414,706 Babcock et al. ------Jan, 21, 1947 11. A process for the production of a metal salt of a fluoroacetic acid which comprises reacting a OTHER REFERENCES fluoroethylenic compound from the group con Henne et al., J. Am. Chem. Soc., vol. 67, pp. 918 sisting of those having the general formula: 25 919 (1945). CFXCYCYZ, and CEXCYCYCFX