United States Patent 0 1C6 Patented Nov
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r: 3,287,425 United States Patent 0 1C6 Patented Nov. 22, 1966 1 2 propanes; acyclic compounds containing one or more car 3,287,425 bon-to-oarbon double bonds such as hexachloropropene, FLUORINATED COMPOUNDS AND THEIR PREPARATION 3-hydropentachloropene, octachlorobutenes, heptachloro John T. Maynard, Brandywine Hundred, Del., assignor to butenes, hexachlorobutenes, hexachloro-1,3-butadiene, and E. I. du Pont de Nemours and Company, Wilmington, perchloro-l,5-hexadiene; saturated carbocyclic compounds Del., a corporation of Delaware such as perchlorocyclopentane and perchlorocyclohexane; No Drawing. Filed Mar. 7, 1961, Ser. No. 93,860 and carbocyclic compounds containing one or two car 14 Claims. (Cl. 260-6533) bon-to-carbon double bond-s in the ring such as octachloro cyclopen-tene. This application is a continuation-in-part of my co 10 As indicated above, the polychlorohyd-rocarbon com pending application Serial No. 12,973, ?led March 7, pounds are added to an agitated suspension of an alkali 1960, now abandoned. metal ?uoride which is either potassium ?uoride, cesium This invention relates to a novel process for preparing ?uoride, or rubidium fluoride. If desired, mixtures of ?uorinated compounds. In addition, this invention re these alkali metal ?uorides may be used. The alkali metal lates to novel 2-hydrohepta?uorobutenes. 15 ?uoride should be ?nely divided and anhydrous. The Fluorine-containing compounds are of great potential amount of alkali metal ?uoride to be used depends upon value for a wide variety of purposes. However, use of the number of chlorine atoms to be replaced in the poly many of these compounds is severely limited because of chlorohydrocarb-on starting material. In order to re the lack of economically practical methods for their prepa place all of the chlorine atoms, at least one mole of alkali ration. This invention provides a continuous process for 20 metal ?uoride should be used per mole of chlorine to the preparation of a variety of ?uorine-containing com be replaced. Preferably, at least 1.1 mole of alkali metal pounds, which method is economically more ‘attractive ?uoride should be used for each chlorine atom to be re than methods heretofore disclosed in the art. placed. A greater amount may be used, but it is usually While the prior art describes various procedures for not necessary to use more than 3 moles of alkali metal preparing ?uorine-containing compounds, in general, these 25 ?oride per mole of chlorine to be replaced. procedures have involved prolonged reaction under rather The solvent which is employed in the process of this severe conditions. vIt is not possible from these dis invention should have a boiling point of at least 150° C. closures to predict the conditions necessary to carry out so that it does not distill out of the reaction mixture and, a continuous process in which the ?uorinated compound of course, should be liquid at the reaction temperature. is removed continuously from the reaction medium. 30 It is preferred that the solvent have a ‘boiling point of ‘It is an object of the present invention to provide a about 10° C. above the temperature of the reaction. novel process for preparing ?uorinated compounds. A Representative solvents which may ‘be used include the further object is to provide novel Z-hydrohepta?uoro lower carboxylic acid amides and preferably those con butenes. A still further object is to provide a process for training from 1 to 4 carbon atoms such as formarnide, the preparation of these Z-hydrohepta?uorobutenes. Other 35 acetamide, propionamide, butyramide, and isobutynamide, objects will appear hereinafter. and their N-alkl or N,N-diaklyl derivatives in which the These and other objects of this invention are accomp alkyl groups are lower alkyl; lower alkyl sulfoxides and lished by a process of continuously preparing ?uorinated sulfones and preferably those containing from 1 to 4 compounds containing at least 3 carbon atoms which com carbon atoms, such as dimethyl sulfone, dimethyl sul prises maintaining at about 150 to 250° C. an agitated 40 foxide, diethyl sulfone, diethyl sulfoxide, dibutyl sulfone, suspension of an alkali metal ?uoride wherein the alkali and dipropyl sulfoxide; cyclic alkylene sulfones, and car metal is selected from the group consisting of potassium, bonates containing from 5 to 6 members in the ring, cesium and rubidium in a solvent having a boiling point such as tetr-amethylene sulfone, pentamethylene sulfone, of at least about 150° C., which solvent is selected from ethylene carbonate, 1,2-propylene carbonate, and 1,3 the group consisting of lower carboxylic acid amides, lower 45 hutylene carbonate; and lactones and lactams containing alkyl sulfoxides, lower alkyl sulfones, cyclic alkylene sul from 5 to 7 atoms in the ring such as 2-pyrrolidone, N fones containing from 5 to 6 members in the ring, cyclic rnethyl-Z-pyrrolidone, caprolactam, 'y-butyrolactone, and alkylene carbonates containing from 5 to 6 members in Z-piperidone. The preferred solvent is N-methyl-Z-pyr the ring, lactones containing from S to 7 atoms in'the rolidone because of its read-y availability and high boiling ring, and lactams containing from 5 to 7 atoms in the 50 point. The amount of solvent to be used is not critical ring; continuously adding to said suspension a polychloro except that su?icient solvent should be present during the hydrocarbon compound which contains at least 3 carbon reaction to suspend the particles of the alkali metal atoms and continuously removing the formed ?uorinated ?uoride and to provide intimate contact of the ?uoride with compound as a vapor; said polychlorohydrocarbon com the polychlorohydrocarbon reactant. pound being. a hydrocarbon compound where at least 50 55 The process is carried out using any conventional equip percent of the hydrogen atoms have been replaced by ment which will provide ‘means for the continuous addi chlorine. tion of the polychlorohydrocarbon starting material to a The novel compounds 2-hydrohepta?uorobutene-2 and slurry or agitated suspension containing the alkali metal Z-hydrohepta?uorobutene-l may be prepared by the ?uoride suspended in the solvent and ‘for the continuous above-described process from ‘hexachloro-1,3-butadiene. 60 removal of volatile products. The solvent-?uoride slurry The polychlorohydrocarbon compounds which are used is ?rst brought to the desired temperature and is main as starting materials in the process of this invention are tained at this temperature during the continuous addition aliphatic and cycloaliphatic hydrocarbon compounds hav of the polyohrlorohydrocarbon reactant. It is preferred ing at least 3 carbon atoms and having at least 50 percent to provide agitation to assure intimate contact of the of the hydrogen atoms replaced by chlorine. Thus, these 65 polychloro'hydroca-rbon reactant with the metal ?uoride. compounds consist solely of carbon, chlorine and, in some Optionally, the solvent-?uoride slurry may also be con~ instances, hydrogen. It is preferred that these polychloro tinuously ‘fed into and withdrawn from the reaction vessel. hydrocarbon compounds contain not more than about 12 A ‘slow sweep of an inert gas such as nitrogen may be carbon atoms. Representative compounds which may passed through the reaction vessel to assist in removal ‘be used include saturated acyclic compounds ‘such as 70 of volatile products. The volatile products may be col octachloropr-opane, heptachloropropanes and hexachloro lected ‘by conventional methods such as by condensation, 3,287,425 3 4. - . solution in a solvent, etc. In some cases it may be de or in combination with other gaseous ?uorinated com sira'ble to maintain the reaction temperature ‘for a short pounds such as dichlorodi?uoro-methane. time after addition of the starting material is complete in The following examples will ‘better illustrate the nature order to recover the maximum amount of ?uo-rinated of the present invention; however, the invention is not product. This is not essential and is usually not necessary. intended to be limited to these examples. Parts are by Although somewhat ' igher or lower temperatures may weight unless otherwise indicated. be used, the reaction is preferably carried out in the range A. The experiments described in Examples 1 to 7 are of about 150° C. to about 250° C. Below 150° C. the conducted by the following method: reaction proceeds too slowly, and temperatures above The reaction is carried out in a ?ask ?tted with an 250° C. are not necessary. The temperature will depend 10 agitator, a gas inlet ‘for a nitrogen sweep, an inlet for con to a certain extent upon the boiling point of the solvent tinuous feed of the polychloro‘hydroca-rbon starting ma— being used. For example, when 'N-methyl-2-pyrrolidone terial, and a Claisen head vented to a series of traps cooled is used as the solvent, a temperature [range of 190-200” C. by solid carbon dioxide. An anhydrous alkali metal may be used. When dimethylformamide is used, as the ?uoride and the solvent are placed in the ?ask. Glass solvent, at temperature of only about 150° C. is attainable. 15 beads (50-150 grams) are added to provide an abrading When temperatures in the lower part of the range are action to expose fresh reaction surfaces. The reaction used, the yield of volatile product may be Somewhat mixture is agitated during the entire process. The re lower than when the higher temperatures are used. The action mixture is heated to the desired temperature and reaction is normally conducted at atmospheric pressure; the temperature is maintained while the po-lychlorohydro however, lower or higher pressures may be used. 20 carbon starting material is introduced continuously The compounds which are obtained as a result of the through the gas inlet. A slow sweep of nitrogen is main process of this invention are ?uorinated materials wherein tained to assist in carrying the volatile products to the the chlorine atoms present in the starting compound have trap system where they are condensed.