3,499,943 United States Patent Office Patented Mar. 10, 1970 2 compounds. The three possible chlorofluoromethanes are 3,499,943 PROCESS FOR PREPARING CHLOROFLUORO formed, principally chlorotrifluoromethane and dichloro METHANES difluoromethane. In general, the reaction involves the re Ferenc M. Pallos, Concord, and Attila E. Paviath, placement of a doubly bonded sulfur atom to a carbon Berkeley, Calif., assignors to Stauffer Chemical 5 atom with the elements of chlorine and fluorine. The active Company, New York, N.Y., a corporation of Del species promoting this replacement is the fluorochloro aWare complex. The applicants do not fully understand the mech No Drawing. Filed Dec. 7, 1965, Ser. No. 512,190 anism involved and therefore do not wish to be limited Int, C. C07 c 17/00 to any specific mode of reaction. However, it is thought U.S. C. 260-653 3 Claims O that first there is an addition of fluorine and chlorine across the carbon-sulfur double bond, followed by a cleavage of the resulting carbon-sulfur single bond and the further ABSTRACT OF THE DISCLOSURE addition of halogens thereto, forming the desired chloro A process for preparing chlorofluoromethanes, such as, fluoromethanes. Within the scope of the above-described dichlorodifluoromethane by reacting the inorganic fluoro 15 reaction is the utility of such compounds that contain car chloro complex AsCl4]+(AsF6]- or ESbCl4]+[SbF6] bon-sulfur double bonds. As for example, thiocarbonyl with carbon disulfide, preferably at autogenous pressure dichloride (CSCl2). It is possible that in thiocarbonyl and at a temperature between about 100 and 300° C. and dichloride the sulfur could be replaced by a chlorine and isolating the chlorofluoromethanes. fluorine to produce chlorofluoromethanes according to the 20 present invention. -ammour The reaction can be carried out at atmospheric pres This invention relates to a new and novel process of sure, for example by adding carbon disulfide to a solution preparing fluorine-containing organic compounds. More of active fluorinating agent, AsCl4]t Asifs) or particularly, it relates to a process of preparing completely SbCl4]+[SbF6]-, and heating the solution. Due to the halogenated methanes wherein at least one of the halogen 25 high volatility of the carbon disulfide conversions are atoms is fluorine and any other halogen is chlorine. lower when operating at atmospheric pressure. It is there The chlorofluoromethanes, such as trichloromonofluoro fore more favorable to conduct the reaction under the methane and especially dichlorodifluoromethane, are ex autogenous pressure developed by the reactants and prod tremely valuable compounds. They find extensive use as lucts at the operating temperature. It is preferred to carry refrigerant liquids, as dielectric fluids, as blowing agents 30 ou the reaction in a pressure vessel. for plastic foams, and as propellants in aerosols. The reaction between carbon disulfide and the fluoro This invention has as a principal object a new and novel chloro complex to give the chlorofluoromethanes may be process for preparing chlorofluoromethanes. Another ob carried out at various temperatures depending upon ject is provision of a process for preparing said chloro whether the reaction is conducted at atmospheric or autog fluoromethanes by a new reaction involving a heretofore enous pressures. At atmospheric pressure, while collect unknown reaction. ing the gaseous products formed, the temperature may be Pursuant to the above-mentioned and yet further objects taken as high as operability permits. A temperature range it has been found that chlorofluoromethanes may be pre of 80 to 100° C. is satisfactory and conveniently obtain pared by the reaction of carbon disulfide with the inor able. When operating under pressure appreciable conver ganic fluoro-chloro-arsenic complex, ASCIIASFs)" or 40 sions are obtained at temperatures in excess of 100° C. with the inorganic fluorochloro-antimony complex, The reaction temperature can be much higher, but there SbCl+ SbF). is normally no advantage in using temperatures above The active fluoroinating agent in the reaction mixture about 300° C. The preferred temperature range is from is the fluorochloro arsenic or antimony complex. The about 200° C. to about 250 C. preparation of this species can be carried out either in 45 The reactor is agitated to facilitate intimate contact situ or in substantia. The physical properties of the fluoro of the reactants. Normally, the reaction under pressure chloro complexes are described in the literature by L. is allowed to proceed for at least one hour and preferably Kolditz (Zeit Anng. Allg. Chem, 280, 313-20 (1955) for five to eight hours. Longer reaction times can be used and 310, 236-41 (1961)). In general, the complexes can as operating conditions dictate to obtain satisfactory con be conveniently prepared in conventional glass equipment. 50 versions. At atmospheric pressure the reaction is carried Arsenic or antimony trifluoride preferably should be chlo out for a sufficient length of time as to offer maximum rinated with a stoichiometric amount of chlorine or an conversion to the chlorofluoromethanes. excess thereof to form the appropriate complex. The com A convenient procedure for conducting the reaction of plex is quite soluble in arsenic trifluoride and thus even an the present invention consists in mixing together the re excess of Asf could be used. A small amount of water 55 actants, carbon disulfide and the selected fluorochloro which acts as a catalyst may be added to the arsenic tri complex, in a pressure vessel. The pressure vessel was fluoride before the addition or chlorine is begun to in Suitably equipped with pressure indicating means. After crease the speed of reaction. sealing the reactants in the pressure vessel, the vessel is The respective proportions of carbon disulfide and the agitated as on a shaker, a rocking mechanism or by inorganic fluorochloro complex are not critical. The re 60 stirring. Suitable means for heating the pressure vessel action will take place over a wide range of conditions to the desired temperature is employed. After reaction for and reactant ratios; however, there exist certain limits the required time, the reactor is cooled and the gases col which make the reaction more feasible. It is desirable to lected in a low temperature trap. The gases thus collected use the two reactants in the molar ratio of at least 2:1, can then be cleaned by passing through a caustic solution complex to carbon disulfide. Our preferred ratio is at 65 to remove acidic vapors and separated by conventional least 4 moles of complex to 1 mole of carbon disulfide. fractionation techniques. When the complex is to be prepared in situ the preferred The following examples illustrate the process of this molar ratio of reactants is at least 2:2:1, arsenic or anti invention. mony trifluoride to chlorine to carbon disulfide. 70 EXAMPLE 1. The reaction produces a mixture of products. However, Seven hundred and fifty milliliters of arsenic trifluoride conditions can be varied to favor the formation of specific was placed in a lecture bottle. Chlorine gas was bubbled 3,499,943 3 4. into it until approximately 40 percent of the arsenic tri was maintained for three hours while the lecture bottle fluoride was converted to the active species complex, was constantly agitated. Thereafter, the lecture bottle was AsClal AsF). To this was then added 126 grams of placed into an oil bath heated to 180° C. and remained carbon disulfide. The lecture bottle was closed and placed in said bath for 2 hours. After cooling to 60° C., the on a shaking device. The lecture bottle and its contents gaseous reaction products were passed through a 30% were heated to 200-230° C. for seven hours, under autog aqueous solution of KOH and then collected in an ace enous pressure developed by the reactants and reaction tone-Dry Ice trap. The reaction yielded CF2Cl3 (38%) products. After cooling to room temperature the gaseous and CFCl (5%). reaction products were passed through a 30 percent aque Whereas, the active fluorinating species in the foregoing ous solution of potassium hydroxide to remove any acidic 0 examples were prepared in substantia, it is within the contaminant gases. The reactor was warmed to 50 C. scope of the present invention to prepare the fluorinating until no more gaseous material was removed. The gases species in situ. This could be done by adding chlorine to were collected in a -78° C. (Dry Ice-isopropyl alcohol) a mixture of selected trifluoride and carbon disulfide trap. Approximately 160 grams of low boiling liquid was under the desired reaction conditions. obtained. The composition as determined by vapor phase 5 Various changes and modifications may be made in the chromatography was: 75 percent dichlorodifluorometh process described herein as will be apparent to those ane, 15 percent chlorotrifluoromethane, 2 percent tri skilled in the chemical arts. It is accordingly intended chloromethane and 8 percent miscellaneous sulfur con that the present invention shall only be limited by the taining compounds. scope of the appended claims. EXAMPLE 2 20 We claim: One hundred milliliters of arsenic trifluoride was chlori 1. The process for preparing at least one member of nated until no more chlorine absorption could be noticed. the group consisting of the chlorofluoromethanes, which This converted approximately 40 percent of the arsenic comprises reacting an inorganic fluorochloro complex se trifluoride to the complex, ASCI+AsF6). The excess lected from the group consisting of AsCl4]+AsF6) and arsenic trifluoride was removed in vacuo. To the com ISbCl +SbF with carbon disulfide, and isolating said plex in a glass reactor at atmospheric pressure was added chlorofluoromethanes. 14.5 grams of carbon disulfide. This mixture was heated 2. A process as stated in claim 1 wherein the reaction slowly up to 90° C. The evolving gases were purified as is carried out at superatmospheric pressure and at temper described in Example 1, supra.