United States Patent Office

Patented June 26, 195i 2558,703 UNITED STATES PATENT OFFICE PREPARATION OFPROPENE TRIFLUOROTRICHLORO Carl I. Gochenour, Niagara Falls, N. Y., assignor to Hooker Electrochemical Company, Niagara Falls, N. Y., a corporation of New York No Drawing. Application January 6, 1948, Serial No. 818 5 Claims. (CI. 260-653) 2 pene are unsatisfactory; when more than six The present invention relates to a method for moles of hydrogen fluoride to one mole of hexa the fluorination of hexachloropropene, and is chloropropene are employed, yields of trifluoro more particularly concerned with the fluorination trichloropropene are decreased by the entrain of hexachloropropene to produce high yields of ment of product in the escaping excess HF. Also, ... trifluorotrichloropropene, and especially 1,1,1-tri the use of more than 6 moles is economically fluoro-2,3,3-trichloro-2,3-propene impractical. (CF3-CCECC) 3. The presence of pentavalent antimony It has been proposed to fluorinate hexachloro halide in catalytic amounts, from about 0.2 to 2.0 propene with antimony (III) fluoride and a cata 10 per cent by weight of the hexachloropropene be lyst, and this method of fluorination, although ing preferred. Representative catalysts are anti operative, is too expensive for economic .com mony (V), chloride, antimony (V) bromide, anti mercialization. It has also been proposed previ mony (V) fluoride, and antimony (V) chlorofluo-. ously to fluorinate hexachloropropene by heating rides. The antimony (V) chloride or chloroflu it together with a fluoromethane and an alumi 5 orides are preferred. Less than about 0.2 per num halide to accomplish exchange of the flu cent of catalyst is usually not as satisfactory for orine atom or atoms in the fluoromethane and practical yields; more than about 2.0 per cent halogen atoms other than fluorine in the hexa does not appreciably increase the yield. chloropropene. This process is more fully dis 4. A reaction temperature between room tem closed in United States Patent 2,404,706, issued 20 perature, e. g., 20-30 degrees centigrade, and July 23, 1946. The halogen-interchange reaction about 100 degrees centigrade; 40-90 degrees cen between a fluoromethane and trihalomethyl tigrade being preferred. Yields of desired prod ethylenic compounds, however, has obvious dis uct appear to decrease with higher temperatures advantages, namely, the necessity of employing when operating at atmospheric pressure, due to an aluminum halide, and that the process de 25 increased volatility and entrainment of product mands two separate steps, i. e., the production of in the escaping HF. the fluoromethane, and reaction of the trihalo 5. The introduction of the substantially anhy methylethylenic compound therewith. It has drous hydrogen fluoride into a mixture of catalyst heretofore been considered that an allyl halide, and hexachloropropene. The hydrogen fluoride such as hexachloropropene, cannot be fluorinated 30 may be introduced batchwise when the reaction with hydrogen fluoride because the first step of is conducted under superatmospheric pressure; Such a reaction is addition to the double bond or or portionwise or continuously when conducted because HF is an active ally polymerization cata at atmospheric pressure, preferably the latter, lyst. Thus, methallyl chloride and hydrogen into the mixture until the required amount has been introduced. fluoride react to form the chlorofluoride 35 6. Agitation of the reaction mixture is required for highest yields. The agitation resulting from (Organic Reactions, New York, John Wiley and introduction of the hydrogen fluoride may be Sons, Inc., 1944, volume II, page 52). sufficient, but additional agitation is preferred. However, in direct contrast to the published 40 7. The pressure preferably should not exceed findings of prior investigators, I have found that autogenous, e. g., the vapor pressure of reactants hydrogen fluoride and hexachloropropene may be and reaction products under the conditions emi reacted, under certain conditions, to produce ex ployed or slightly above. This pressure is at ceedingly high yields, up to 77 per cent, of tri tained in a closed autoclave. Pressures lower than autogenous may be utilized, but pressures fluorotrichloropropene, without addition to the 45 below atmospheric are not generally satisfactory. double bond. Excessively high pressures over and above the The conditions, which I have found necessary autogenous pressures attainable, appear to reduce for the fluorination reaction are as follows: the yield of desired product, possibly by causing 1. The use of substantially anhydrous hydrogen hydrogen fluoride addition to the double bond of fluoride. 50 2. A reactant ratio of at least three moles of the product. hydrogen fluoride for each mole of hexachloro 8. The reactor for the process may be one of . propene. When less than three moles of hydro several types. A rocking autoclave constructed gen fluoride per mole of hexachloropropene are of steel or iron is satisfactory. Alternatively, a employed, COnversions to trifluorotrichloropro 55 reactor of Suitable material, e.g., nickel, iron, or 2,558,708 3 4. copper, equipped with a water or Dry-Ice cooled rate of 2.25 parts per hour for a period of 8.75 reflux condenser, a scrubber for neutralizing hours, the temperature of the reaction being evolved acids, and a discharge line may be em- maintained at about 40 degrees centigrade dur ployed. The type of apparatus is not to be ing the course of the reaction. Fractional distill construed as limiting the invention. 5 lation of the dry crude product gave a 56.6 per 9. The reaction product may be separated ac cent yield of trifluorotrichloropropene. cording to conventional procedure for the treat ment of halogen-containing reaction products, Example y e.g., by cooling, Washing with water, neutraliz Example I was repeated except that 30.5 parts ing with dilute base, drying, and fractionally dis- 10 of hydrogen fluoride was introduced at the rate tilling to isolate the desired 1,1,1-trifluoro-2,3,3- of 1.97 parts per-hour for a period of fifteen and trichloro-2,3-propene. One-half hours. Fractional distillation resulted This invention will be further understood from in a 65 per cent yield of trifluorotrichloropro a consideration of the following illustrative ex pene, amples, in which the quantities are stated in 5 Eacample VI parts by weight and the yields are given in per Ten thousand parts of hexachloropropene and cent of theory, based on the hexachloropropene 30 parts of pentavalent antimony halide catalyst charged. (SbFs) were charged into an apparatus similar Eacample I to that used in Example I, except that the re Seventy-eight and one-fourth parts of hexa 20 actor was constructed of iron and was not nickel chloropropene and 0.7825 part of antimony pen lined. Three thousand six hundred parts of an tachloride were charged into a nickel-lined re hydrous hydrogen fluoride was introduced into actor which was provided with hydrogen fluoride the agitated charge over a period of four hours inlet, agitator, water-cooled reflux condenser, at the rate of 900 parts per hour, and the reac scrubber for neutralizing evolved acids, and a 25 tion temperature was increased to 90 degrees discharge line. Twenty-two and nine-tenths centigrade during the reaction. The crude prod parts of substantially anhydrous hydrogen fluo uct was treated as in Example I and on frac ride was introduced into the agitated reactor at tional distillation yielded 132 parts of trifluoro the rate of 1.9 parts per hour over a period of trichloropropene boiling between 86.9 and 89.9 twelve hours. The temperature of the reaction degrees centigrade. mixture was increased gradually from about The results and differences in reaction condi twenty-three degrees centigrade at the begin tions of the foregoing examples can be more ning pf the reaction to about forty-seven degrees readily observed from the following table: centigrade at the end of the twelve-hour period. 35 After introduction of the hydrogen fluoride was Moles HF Temper- o complete, the reaction products were cooled, Ex- Per Cent, Reaction. Yield, washed with water, neutralized with a dilute afie Catalyst P:gle age, "FG" cFéi, aqueous Solution of sodium hydroxide, Separated, Hours Per cent dried with soda, ash, and fractionally distilled. I------ i.0% SbCls--- 3.65 23-47 2 76.6 40 II----- 0.5% SbCls---- 4.57 23-45 2.5 64, 6 The forty-eight parts of trifluorotrichloropro III---- 1.0% ShCls.--- 3.0 23-47 0.5 71.4 pene, boiling between 86.5 and 89.7 degrees cen IV---- 0.5% SbCis-- 3.48 40 8.75 56.6 tigrade, having a specific gravity of 1.6095 at V----- 1.0% SbCls--- 4.84 23-47 5.5 65.0 25/4 and no of 14100 was separated, a 76.6 VI.-- 0.3%, SbFs---- 4.5 90 4.0 1.65 per cent yield. - 45 The product of Example VI included difluoro Eacample II tetrachloropropane in a yield of 67.5%. The low Seventy-one parts of hexachloropropene and yield of trifluorotrichloropropene in Example VI 0.355 part of antimony pentachloride were is attributable to the short reaction period, the charged into an apparatus similar to that used in Small proportion of catalyst and the higher tem Example I. Twenty-six parts of anhydrous hy 50 perature. drogen fluoride was introduced into the agitated Various modifications may be made in the reactor at the rate of about 1.93 parts per hour present invention without departing from the over a period of 13.5 hours. The temperature Spirit or Scope thereof and it is to be understood Of the reaction mixture was maintained from that I limit myself only as defined in the ap about 23 degrees centigrade to about 45 degrees 5 5 pended claims.

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