United States Patent (19) 11 Patent Number: 4,885,416 Mader (45) Date of Patent: Dec
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United States Patent (19) 11 Patent Number: 4,885,416 Mader (45) Date of Patent: Dec. 5, 1989 (54) FLUOR NATON PROCESS 4,078,007 3/1978 Ferstandig. 570/170. 4,091,043 5/1978 Ohsaka et al. ...................... 570/170 75 Inventor: Frederick W. Mader, Kennett 4,438,088 3/1984 Weaver ............................... 570/170 Square, Pa. FOREIGN PATENT DOCUMENTS (73) Assignee: E. I. Du Pont De Nemours and Company, Wilmington, Del. 589167 6/1947 United Kingdom ................ 570/170 92.5909 5/1963 United Kingdom ................ 570/167 (21) Appl. No.: 154,421 OTHER PUBLICATIONS 22 Filed: Feb. 9, 1988 Advances In Fluorine Chemistry, Stacey et al, vol. 3, Related U.S. Application Data pp. 117 and 146-154, Butterworths & Co. Ltd., London (1963). 63 Continuation of Ser. No. 789,288, Oct. 18, 1985, aban doned, which is a continuation-in-part of Ser. No. Primary Examiner-J. E. Evans 507,084, Jun. 23, 1983, abandoned. Attorney, Agent, or Firm-Charles E. Feeny (51) Int. Cl'...................... CO7C 17/20; C07C 17/22; 57 ABSTRACT C07C 19/02; C07C 19/08 52) U.S. C. ..................................... 570/170,570/167 A continuous process for florinating haloalkanes con (58) Field of Search ................................ 570/170, 167 taining at least one nonfluorine halogen atom wherein antimony pentachloride is reacted with HF to produce 56 References Cited an antimony (V) chlorofluoride and HCl is removed. U.S. PATENT DOCUMENTS The antimony chlorofluoride thus produced is then 1,978,840 10/1934 Henne ..... - ... 570/170 transferred to a separate reaction zone where it is re 2005,705 6/1935 Daudt et al. 570/170 acted with the haloalkane, thereby replacing a portion 2,005,708 6/1935 Daudt et al. ........................ 570/170 of the nonfluorine halogen in the haloalkane with fluo 2,005,711 6/1935 Daudt et al. ........................ 570/170 rine of the antimony (V) chlorofluoride. 2,510,872 8/1984 Downing ....... ... 570/170 2,786,738 3/1957 Ruh et al............................. 570/167 3,240,826 3/1966 Davis .................................. 570/170 28 Claims, 5 Drawing Sheets 7 U.S. Patent Dec. 5, 1989 Sheet 1 of 5 4.885,416 F G. 1 U.S. Patent Dec. 5, 1989 Sheet 2 of 5 4.885,416 F G. 2 22 2O3 2O6 23 2O4. 202 2O5 2io E 59 207 5 -2O8 U.S. Patent Dec. 5, 1989 Sheet 3 of 5 4.885,416 F G. 3 U.S. Patent Dec. 5, 1989 Sheet 4 ofs 4,885,416 F G. 4 U.S. Patent Dec. 5, 1989 Sheet 5 of 5 4.885,416 F G. 5 Ol 4,885,416 1. 2 virtually all by-product HCl in addition to significant FLUORNATION PROCESS amounts of HF which are found in the crude reaction product as an azeotrope with the fluorinated reaction CROSS-REFERENCE TO RELATED products. Another factor which complicates purifica APPLICATION tion of the fluorinated reaction products resides in the This application is a continuation of application Ser. fact that boiling points of some of the fluorinated prod No. 789,288 filed Oct. 18, 1985, now abandoned, which ucts overlap the boiling point of HCl or are not far in turn is a continuation-in-part of application Ser. No. removed from the boiling point of HF. For example, in 507,084 filed June 23, 1983, now abandoned. the fluorination of chloroform, the crude reaction prod 10 uct includes CHCl2F (b.p. 8.9° C), FIELD OF INVENTION CHClF2 (b.p. -40.8° C), CHF3 (b.p. -82. C.), HCl This invention relates to a continuous process for (b.p. -85. C.) and HF (b. p. 19.4° C). Moreover, the manufacturing fluorinated derivatives of alkanes. production of CHF3 normally exceeds its demand, so that its overproduction constitutes an economic pen BACKGROUND OF THE INVENTION 15 alty. Fluorination of a haloalkane by exchange of fluorine Aqueous scrubbing of the reaction product can be for another halogen is the most generally used tech used to remove the by-product HCl and unreacted HF: nique for preparing fluorinated alkanes. It is not usually Daudt et al. U.S. Pat. No. 2,005,705. However, such an practical to react a mixture of a haloalkane with HF as approach is an uneconomic one since it sacrifices most the reaction proceeds sluggishly and requires very high 20 of the HF as waste and necessitates subsequent sale of temperatures and pressures. In 1892 Swartz synthesized the by-product HCl as a 30% aqueous solution; Hamil CCl3F in a liquid phase reaction in which the reaction ton, Advances in Fluorine Chemistry, Vol. 3, Butters product of SbF3 and Br2 was contacted with CC14: Bull. worth (1963). Separation of products from by-products Acad. R. Belg, 1892(3), 24, 309. However, it was not and unreacted HF has been accomplished by use of until 1926 that CF4, the simplest perfluorocarbon, was 25 series of distillation techniques. But that means of puri isolated. At just about that point, the needs of the refrig fying the products requires a great deal of energy for eration industry prompted considerable development in refrigeration and the installation of a great deal of pres the field. The first commercial synthesis developed surized equipment, resulting in high capital costs for thereafter (about 1930) was a continuous process construction of manufacturing facilities and high oper wherein hydrogen fluoride and haloalkanes containing 30 ating costs as well. Moreover, such anhydrous pres halogen other than fluorine were reacted in the pres sured distillation techniques do not effect separation of ence of antimony pentachloride; Daudt et al., U.S. Pat. fluorinated product/HF azeotropes. Further processing Nos. 2005,705 and 2,005,708. The reaction is that of is required, such as scrubbing with water (U.S. Pat. No. replacing Cl, Br or I of the haloalkane with fluorine of 35 2,450,414) or concentrated H2SO4 (U.S. Pat. No. the hydrogen fluoride. Most generally, the haloalkanes 3,873,629). of choice are chloroalkanes because of their availability The corrosivity of HF is well known. In the presence and their tendency to undergo fewer side reactions of small amounts of antimony pentachloride (used in the during the exchange reaction than their bromo or iodo continuous process described above), its corrosivity analogs. The fluorination reaction may be represented 40 increases dramatically. The reactor systems used in the by the following equation using chloroform as the illus prior art continuous process have been known to fail trative haloalkane: because of corrosion. That effect is attributable to the fact that in that process, HF and the chlorocarbon are Antimony continuously fed into a static charge of antimony penta x HF + CHCls-Chloride seCHCls-F. + x HC. 45 chloride, a liquid under the reaction conditions, in a reactor system that contains no mechanical agitation. whereinx is 1-3. The process is carried out by continu As a consequence, there is a very high mol ratio of HF ously cofeeding hydrogen fluoride and haloalkane into to antimony pentachloride at the point at which the HF antimony pentachloride. Generally, a mixture of first comes in contact with the antimony pentachloride. CHCl2F, CHClF2 and CHF3 is obtained, the particular 50 At such a high HF to antimony pentachloride ratio, the proportion of the fluorinated products depending upon corrosivity of the mixture increases dramatically. the reactant ratios and the reaction conditions. For each It is therefore an object of the present invention to mol of hydrogen fluoride undergoing the exchange provide an economical, energy-efficient, continuous reaction, one mol equivalent of hydrogen chloride is process for the production of fluorinated haloalkanes. It generated. Usually HF is used in excess so as to ensure 55 is a further object of the present invention to provide a maximum utilization of the haloalkane reactant. There continuous haloalkane fluorination process which will fore, the crude reaction product will contain HF as well provide crude fluorinated products substantially free of as a mixture of CHCl2F, CHCIF2, CHF3 and HC. hydrogen halides, in particular CHClF2 free of its azeo Despite a number of disadvantages in it, the above trope with HF, and CHF3 as well as CClF3 free of described continuous process has been the primary 60 close-boiling HCl. It is a still further object of the pres manufacturing process for preparing virtually all of the ent invention to provide a continuous haloalkane fluori major fluorocarbons and chlorofluorocarbons which nation process which minimizes costs associated with have been manufactured since industrial production of the purification of reaction products. It is another ob them commenced. Since the beginning of industrial ject of the present invention to provide a continuous production of such products, efficient utilization of HF, 65 haloalkane fluorination process which results in re its removal from products and by-products of the reac duced corrosion of equipment used in the process. It is tion, and its recovery for re-use have been important still another object of the present invention to provide a considerations. In addition, it is necessary to remove continuous haloalkane fluorination process which re 4,885,416 3 4. sults in waste streams that are environmentally more (4) removing spent antimony (V) chlorofluoride from acceptable. Yet another object of the present invention said third zone into a fourth zone wherein said spent is to provide a continuous haloalkane fluorination pro antimony chlorofluoride is freed of volatile material and cess in which anhydrous HCl is recovered substantially then recycled to the first zone for refluorination with free of HF and fluorinated haloalkanes. Still another 5 hydrogen fluoride, and object of the present invention is to provide greater (5) removing fluorinated haloalkanes from said third flexibility in the production of fluorinated chlorome zone to a separation means to recover fluorinated ha thanes in which the overproduction of low-demand loalkanes essentially free of hydrogen halide.