3,201,483 United States Patent Office Patented Aug. 7, 1965 2 settle out, interfering with stirring of the reaction mixture and causing consequent difficulties in temperature con 3,201,483 METHOD OF FLUORNATING WITH ANTMONY trol. PENTAFLUORDE Reaction vessels suitable for use in the present inven Ralph A. Davis, Midland, Mich., assignor to The Dow tion should be constructed of materials which are inert Chemical Company, Midland, Mich., a corporation of to the reactants and the products of the present invention. Delaware Monel vessels have been found to be suitable but any No Drawing. Filed Aug. 22, 1962, Ser. No. 218,532 vessel having the necessary inertness is appropriate. The 6 Claims. (C. 260-653.8) size of the reactor is dependent upon the amount of prod O uct desired and on the temperature control necessary to This invention relates to a novel process in which obtain the desired product in the desirable yield. antimony pentafluoride is used to selectively fluorinate Appropriate starting materials for the present inven bromine-containing organic compounds. tion are hydrocarbons containing from two and to four Antimony pentafluoride has been proposed in the past carbon atoms, at least one bromine atom, and at least as a fluorinating agent. However, its use to fluorinate or one hydrogen atom. Preferred starting materials are eth ganic bromine compounds which are normally difficult to 15 anes containing at least two fuorine atoms, at least two fluorinate usually resulted in a large amount of decompo bromine atoms, and at least one hydrogen atom. It is sition and dehydrohalogenation of the organic com desirable that both fluorine atoms are on the same carbon pounds. Attempts at fluorination of normally easily atom. Examples of such preferred starting materials are fluorinated organic compounds by means of antimony 20 CF-CHBr and CBrF2-CHBr3. pentafluoride usually resulted in highly exothermic re Reaction is usually carried out at a temperature of actions giving perfluorinated products. it was also gen from about 20° centigrade to about 70 centigrade. The erally noted, that the salts formed in the fluorination re reaction temperature is generally limited by the boiling action became practically solid after about one fluorine point of bromine unless pressure is used. However, too atom per mole of antimony fluoride has been used. So 25 high a pressure may cause over-fluorination of some of the lidification of the salts tended to cause a loss of control organic materials. Therefore, atmospheric pressure is of the reaction and made regeneration of the fluorinating generally used except with low boiling compounds where agent virually impossible. Neither hydrogen fluoride nor pressure may be necessary in order to maintain the re fluorine could accomplish significant regeneration. actants or intermediate products liquid and in the re It is an object of the present invention to provide a 30 action Zone. process in which antimony pentafluoride may be used in The products of the present invention are hydrocarbons an easily controllable manner to selectively fluorinate containing from two to four carbon atoms and containing bromine containing organic compounds. at least one fuorine atom. Preferred products of the It is a further object of the present invention to pro present invention are those which contain two carbon vide a process in which the spent antimony fluoride fluori 35 atoms, at least one hydrogen atom, at least one bromine nating agent may be easily regenerated. - - - atom, and at least three fluorine atoms. Such products It has now been discovered that when antimony penta are useful as anesthetics, aerosol propellants, blowing fluoride is mixed with bromine, fluorination of organic agents for foaming plastic materials, and the like. materials may be carried out with a high degree of con Regeneration of the antimony pentafluoride may be trollability. It has also been discovered that when the 40 carried out in the same vessel, if desired. Usually, re process of the present invention is used bromine is selec generation is begun by adding to the spent antimony tively replaced from the organic moleculie by fluorine fluoride-bromine mixture an amount of regenerating agent from the fluorinating agent. such that for each fluorine atom to be placed on the it has been further discovered that when the fluorina antimony an equal number of atoms of fluorine will ap tion process is carried out in bromine to maintain react pear on each mole of the regenerating agent. ants and products in a liquid form, the fluorinating agent Suitable regenerating agents for use in the present in may be regenerated in situ through the use of such re vention are fluorine, bromine trifluoride, bromine penta generation agents as fluorine, bromine trifluoride, bromine fluoride, chlorine trifluoride, iodine pentafluoride, and the pentafluoride, chlorine trifluoride, iodine pentafluoride, like. and the like. 50 egeneration is usually run at a temperature of from The process of the present invention may be practiced about 0° centigrade to about 50 centigrade at atmos by mixing a desired amount of antimony pentafluoride pheric pressure. If the regeneration is run at too low a with bromine and placing the liquid mixture in a suitable temperature there is a danger of accumulating unreacted reaction vessel. To the vessel may then be added the halogen fluoride which may react violently upon warming organic compound containing bromine, the reaction usu 55 of the mixture. Too high a temperature will usually ally occurring immediately thereby to replace at least one cause a wasteful loss of bromine from the reaction mix bromine atom on the organic molecule with fluorine. ture. - - - - - - Bromine is desirably added to the antimony pentafluo The process of the present invention may be more easi ride in an amount sufficient to permit reaction tempera ly understood in light of the following examples which ture control and to maintain reactants in the fluid state 60 are set forth to illustrate but are not to be construed to or at least in a fluid suspension throughout reaction. Usul limit the present invention. - ally bromine in an amount by weight of about 4 to about 4 times as much as the antimony pentafluoride used is Example 1 adequate. - To a one liter Monel flask equipped with a stirrer, a Antimony pentafluoride is used in any amount which 65 nickel reflux condenser and a nickel dropping funnel were may be convenient when taking into account the reactor added about 4 mole antimony pentafluoride and about size and the amount of organic material to be fluorinated. 350 grams of bromine. The mixture was kept at room Usually at least one mole of antimony pentafuoride temperature and CFCHBr, was added slowly until finally should be present for each atom of bromine on the or 100 grams or 0.41 mole had been added to the reaction ganic molecule which is to be replaced by fluorine. If 70 vessel. The reaction was slightly exothermic at first and less antimony pentafluoride than one mole per bromine then slowed down. After all the organic had been added atom to be replaced is used large quantities of solids may the reaction mixture was heated until bromine refluxed 3,201,483 3 4. on the condenser. At the end of one hour the reaction fluoride, iodine pentafluoride, or the like. The regenera was essentially complete and the condenser was allowed tion product mixture of bromine and antimony pentafluo to warm to about 35 to 40 degrees centigrade in order to ride is useful as a fluorinating agent which selectively re permit all the products to distill from the bromine reflux. places bromine on an organic molecule to the desired The collected product was scrubbed through a 10 percent degree of fluorination. Sodium hydroxide solution in order to remove any free Various modifications may be made in the present bromine. Seventy two grams of crude product were re invention without departing from the spirit or scope there covered and analyzed by vapor phase chromatography of and it is to be understood that I limit myself only as and found to contain about 97.7 mole percent defined in the appended claims. 10 I claim: CFCHBrF 1. A process for the fluorination of straight chain, sat 1.5 percent CFCHF, and an unknown material, prob urated hydrocarbons having from two to four carbon - ably CFCHF, in an amount of about 0.8 percent. The atoms and containing at least one bromine atom, com recovery of organic material was about 97 percent. prising reacting said hydrocarbon, at a temperature of Example 2 15 from about 20 to about 70 degrees centigrade, and at a pressure sufficient to maintain the reactants liquid, with Using substantially the same procedure as that shown a mixture containing antimony pentafluoride and from in Example 1, 0.33 mole of CFBrCHBr was fluorinated about one-fourth to about four times its weight of bromine, using antimony pentafluoride in bromine. Recovery of said mixture being further characterized in that the bro 98 mole percent of the organic charged was made. Prod 20 mine is present in an amount sufficient to maintain said uct analysis showed that 99.2 percent of the product was antimony pentafluoride and the antimony salts formed in CFCHBrF, the remainder being CFCHF. the reaction in a liquid suspension thereby to selectively Example 3 replace at least one bromine on said hydrocarbon with In order to illustrate the usefulness of this invention fluorine, and separating fluorinated hydrocarbon product a comparison experiment was carried out in which no from the reaction mixture thus formed. bromine was used with the antimony pentafluoride. Two 2. A process for the fluorination of 2,2-di-bromo 1,1,1- hundred fifty-one (251) grams of antimony pentafluoride trifluoroethane comprising, reacting 2,2-dibromo 1,1,1- trifluoroethane at a temperature of from about 20 to about were charged to a 1 liter Monel flask equipped with a 70 degree centigrade, and at a pressure sufficient to main reflux condenser and a dropping funnel.