United States Patent Office Patented Nov
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3,770,838 United States Patent Office Patented Nov. 6, 1973 1. 2 Suitable ionizable fluoride salts include potassium 3,770,838 PROCESS FOR PREPARING FLUOROCARBON fluoride, rubidium fluoride, cesium fluoride, silver fluoride HALDES and tetra (lower alkyl) ammonium fluoride. Potassium Robert E. A. Dear and Cyril Woolf, Morristown, N.J., fluoride is preferred. 5 Suitable aprotic, polar, liquid reaction medium include assignors to Allied Chemical Corporation, New York, acetonitrile, dimethylformamide, dimethylsulfoxide, di No Drawing. Filed June 2, 1971, Ser. No. 149,362 methylacetamide, glycol ethers, cyclic polymethylene nt. Ci, C07c 17/04, 19/08 sulfones, and the like. U.S. C. 260-653 4 Claims The reaction is conveniently carried out at room tem O perature, but temperatures above or below room tempera ture, e.g. about -40° C. to about 100 C., can be em ABSTRACT OF THE DISCLOSURE ployed if desired. Similarly, the pressure employed is not Fluorocarbon halides are prepared by reacting an un critical and can be above or below atmospheric pressure saturated fluorocarbon with a cyanogen halide and an as desired. The reaction is conveniently carried out at ionizable fluoride salt. 5 pressures autogenously developed at the reaction tem peratures employed. In accordance with this invention, fluorocarbon halides The reactants and products of the process of this inven having the formula tion are all well-known compounds of established utility. The following examples further illustrate the invention. 20 In each example, the reaction was carried out under sub stantially anhydrous conditions. EXAMPLE 1. are prepared by reacting a perfluoroalkene having the Eight grams of cyanogen chloride and 19.5 grams of formula perfluoropropylene were added to 8 grams of potassium fluoride and 80 ml. of acetonitrile at -78° C. After the reaction mixture, which was sealed, had warmed to room temperature, the pressure of the reaction mixture rose with a cyanogen halide and an ionizable fluoride salt, as to a maximum of 56 p.s.i.g. in about 2 hours and then represented by the following equation 30 gradually subsided to a constant pressure of 29 p.s.i.g. The volatile component of the reaction mixture was then bled into a trap maintained at -78° C. and identified as hexa fluoroisopropyl chloride. The yield was 13.8 grams. EXAMPLES 2-9 Following the general procedure of Example 1, per In similar manner, fluorocarbon halides having the fluoro-2-butyne and various perfluoroalkenes were reacted formula with cyanogen chloride or cyanogen bromide and potas X F sium fluoride or silver fluoride in an aprotic, polar liquid 40 reaction medium. In each instance the desired fluoro carbon halide was obtained in accordance with this are prepared by reacting a perfluoroalkyne having the invention. formula The reactants and reaction media employed in Exam R-C s C-Rf ples 1-9 are tabulated in Table I below. TABLE I Fluorocarbon Fluoride Cyanogen Example reactant Salt halide Medium Product CFCF-CF. KF CNC CH3CN CFCFCCF CFCF-CF--- KF CNBr. CH3CN CFCFBrCF3 CFCF-scCF. KF CNBr. Sulfoane 1 CFCFBrCFs CFCF-scCF. KF CNBr. DMF 2 CFCFBrCF CFCF-CF--- AgF CNBr. CH3CN CFCFBrCFs CFCF-CF--- AgF CNC CH3CN CFCF ClCF Cyclo-C5Fs------ KF CNBr. DMF Cyclo-C5FBr Cyclo-C6F10----- KF CNBr. CH3CN Cyclo-C6FBr 9------------ CFCs CCF. KF CNBr. Sulfolane CFCF-cCBrCFs 1 Tetramethylenesulfone. 2 Dimethylformamide. with a cyanogen halide and an ionizable fluoride salt in We claim: accordance with the following equation 1. A process for preparing a fluorocarbon halide having X F the formula Rt-CEC-Rf' -- CNX -- MF --> Rt-C=C-Rf' -- MCN 60 The reactions are carried out in an aprotic, polar liquid reaction medium under substantially anhydrous condi tions. In the above formulas: X is chlorine, bromine or k . iodine, preferably chlorine or bromine; R is a perfluoro wherein X is chlorine, bromine or iodine, R is a per alkyl radical; R is fluorine or a perfluoroalkyl radical; 65 fluoroalkyl radical and R is fluorine or a perfluoroalkyl and the total number of carbon atoms in R and Rf' is radical, with the total number of carbon atoms in R and from 1 to 12, preferably 1 to 8. Rf and R together can R being from 1 to 12, which process comprises reacting form a cyclic alkyl radical. a perfluoroalkene having the formula The fluorocarbon halide product is recovered from the reaction mixture in accordance with conventional meth ods, such as fractional distillation. 3,770,838 3 4. wherein R and R are as defined above, with a cyanogen ride, silver fluoride, or tetra (lower alkyl) ammonium halide having the formula CNX, wherein X is as defined fluoride. above, and an ionizable fluoride salt selected from the 4. The process of claim 2 wherein X is chlorine or group consisting of potassium fluoride, rubidium fluoride, bromine. cesium fluoride, silver fluoride, and tetra (lower alkyl) am- 5 References Cited monium fluoride in an aprotic, polar liquid reaction me dium under substantially anhydrous conditions. Bayer: Chemical Abstracts, 72, 66424J (1970). 2. The process of claim 1 wherein the total number of DANIEL D. HORWITZ, Primary Examiner carbon atoms in R and Rf' is from 1 to 8. 3. The process of claim 2 wherein the ionizable fuoride 0 U.S. C. X.R. salt is potassium fluoride, rubidium fluoride, cesium fluo- 260-653.3 .