2,413,696 Patented Jan. 7, 1947 UNITED STATES. PATENT . OFFICE FLUOROHYDROCARBON Frederick B. Downing, Carneys Point, and' Anthony F. Benning and ‘Robert C. McHarness, Woodstown. N. J ., assignors to Kinetic Chemi cals, Inc., Wilmington, DeL, a corporation of Delaware No Drawing. Application June 29, 1944, Serial No. 542,820 1 Claim. (01. 260—653) This invention relates to the preparation of organic ?uorine compounds by pyrolysis. In the applications identi?ed as Benning et al., Serial No. 344,666, ?led July 10, 1940, issued as U. _S. Patent 2,365,516, dated December 19, 1944, and Banning Serial No. 379,473, ?led February 18, 2 dium for the quick freezing of foods as described in U. S. Patent 2,059,970. It is also useful as a solvent, as a reaction medium and as an inter mediate in chemical syntheses. . Although for the production of particular com pounds the reaction will be carried out under well-controlled conditions of time, temperature 1941, issued as U. S. Patent‘ 2,343,252, dated and pressure, complex mixtures of compounds of March ‘7, 1944, are, disclosed two processes in various molecular weights can be produced by ~volving a reaction between a ?uorohydrocarbon subjecting the compounds to reaction conditions and HCl in the presence of a catalyst. Those 10 for extended periods of time. Pressures may reactions may be described as additive, since also be used to vary the results, although for the their apparent course is the addition of HCl purposes of economy and safety each particular to the ole?ne in the place of double bonds. Those reaction should be carried out with the lowest reactions were carried out at comparatively low pressure consistent with optimum results. For 15 temperatures, in most cases below 350° C., be example, pressures of four atmospheres absolute cause those temperatures were satisfactory and have been found satisfactory in many cases. In because observations of a limited number of ex general, operations may be carried out at pres periments at higher temperatures showed the sures between .1 and 10 atmospheres absolute. existence of what were thought to be undesirable but other pressures are useful and may be em 20 side reactions. We have now discovered that the ployed when an increase in efficiency will re side reactions are of a fundamentally different nature than 1101 addition and that they can be sult. put to valuable use. , produced essentially by heat. It is,.therefore. It is an object of this invention to produce ‘ , ,_ This is a pyrolytic process. The reaction is important to select a temperature Which will ef organic compounds by pyrolysis. Another object 25 ficiently produce the reaction. The temperature ‘of the invention is to produce compounds which should be selected to give optimum production are useful, by methods which are economically and technically satisfactory. Another object of the invention is to produce new ?uoro hydrocar bons. A particular object of the invention is to synthesize organic compounds having ?uoralkyl ' chains by the pyrolysis of ?uorohalogen'o carbon compounds. Another object of the invention is to produce the compound CsFsHz. According to our vinvention ?uo-ro-chloro or bromo alkanes, fluoro-chloro or bromo alkenes, and ?uoro alkenes, which may otherwise be called‘ ?uoro-chloro or bromo saturated aliphatic, of the desired product. We have found that, ex cellent pyrolytic results have been produced at temperatures between 600° and 1000" C., but that particular reactants have pyrolyzed at tem peratul‘es as low as 400° C. and above‘ 1000” C. under appropriate conditions of time and pres sure. Electrical heating is efficient, but any method of heating may be applied. The tem peratures which are used must be chosen in view of the materials that. compose the reaction ap paratus. . The time of exposure of the reactants to the pyrolytic conditions is a matter of considerable and fluoro unsaturated aliphatic compounds, are 40 importance where a particular product is desired. made into other compounds by pyrolysis. As a Extending the period of exposure frequently starting material, we prefer to 'use CHFzBr which, produces compounds of increased molecular ?uoro-chloro or bromo unsaturated aliphatic, when pyrolyzed under suitable conditions, will yield a reaction mixture containing CsFsHz. The compound C3F6H2 is a new chemical com pound which can be separated from the reaction mixture by fractional distillation. The com pound CaFsHz is particularly adapted for use as ' a refrigerant in an absorptive or adsorptive sys weight. In general, the reaction proceeds eiliciently in the absence of catalysts. The process is preferably carried out‘continu ously by passing the convertible material through a tube heated to a pyrolytically e?ective temper ature. The tube should be composed of a ma tem because of its boiling point, volatility, low 50 toxicity and because it has two very active atoms for hydrogen bonding. These properties render ‘ it especially suitable for use in a system using a terial which is inert to the reaction and the re action products. Carbon and thenoble metals are su?iciently inert and have proved to be sat isfactory materials for the construction of re solvent having a donor atom such as polyglycol ' 55 action chambers. The chamber need not be ethers and the like, and as an immersion me "2,418,698. 3 wholly-composed of the inert material, but may ' s ' having-a boiling point of -a1° 0.; HCaFsBr boil-' ing‘at 40°-41° C. and having a vapor density of 5.76 g. per liter at 28° C. and 452 mm. ‘be lined with it. Reaction chambers containing a platinum lining are particularly satisfactory. The‘ process may be carried ‘out in batches rather than continuously, but continuity is preferred. ‘ The following example has been carried out and Because of the wide differences in the boiling points of the components of the reaction mass, . they can be readily separated by fractional distil has been selected for illustration. ~ The applicants ‘ present this example, not as constituting any lim lationand the CaFcHa recovered. We believe that the compound CJFQH: has the structural formula itation of the work which has actually been done, CHFFCFFCHFM, since, upon chlorination, it but as su?iciently representative to enable per yields the known compound CC?'FCFa-CCIFL sons skilled in the art to practice the invention. A suitable method of chlorinating CaFoHa is as In this example, the terms "conversion" and " follows!’ _ “amount converted” include the assumption that A 5-liter Pyrei: ?ask was evacuated and 25 cc. the disappearance of one mol of the primary or ' of water was introduced, followed by 7.5 g. of ganic material resulted in the liberation of one 15 CaF'sHz. Chlorine'was then passed in (in'absence mol of halogen acid. ’ This assumption is war of light) until the absolute pressure in the ?ask ranted by the close agreement between the ?gures reached 1.2 atmospheres. The ?ask was then ir - for conversion obtained by acid analysis and the . radiated with a Photo?ood lamp. The tempera actual primary material which disappeared. The ture. rose from 30° C .to 45° C. ‘and the pressure. temperatures of the reactions were measured with 20 fell. ‘ After the pressure became steady, irradia a thermocouple which was placed in contact with tion was continued‘ for two hours. The liquid the outer surface of the reaction tube near the content of the ?ask was poured out and the lower - center of the heated zone, so that the true average , layer separated, washed‘ successively temperatures vof the gases ‘in the tube may have been somewhat lower than the‘ values given. _ , -, Example XX . tically the entire product was found to boil at ' 34.6” C. at 760 mm. pressure. CHFnBr was passed through a platinum-lined -' ' Inconel-jacketed nickel tube, 13.7 mm._i.-d. x 108 with water, ‘ and 10% NazSO'a, and dried over CaClz. 0n dis 25 _ tillation through a laboratory precision still,- prac ' . ' p . From all of the above, it‘willbe apparent that cm, at a rate of about 42.6 g. per hour while the .30 by our invention, we have obtained a novel chem- ' ical compound which has novel properties render pressure in the tube was kept at approximately ing it valuable and useful for a variety of pur-_ onev atmosphere. The . tube temperature was ' , poses. maintained at about 615° C. over an estimated This is a continuation-in-part of our applica length-of 200 mm. by electrical heating. Free bromine was detected in the wash water. The re 35 tion Serial No. 435,064 for “Compositions of mat. ter and pyrolytic methods of synthesizing them," action products were washed with water, .dried filed March 17, 1942, issued as \U. 8. Patent and condensed in receivers cooled to about —70° . . C. A receiver cooled in liquid nitrogen was placed 2,387,247, dated October 23, 1945. We claim: . ‘after the receiver cooled to —7_0.° C. Acid analysis The compound represented ' formula showed a conversion of about 46%., A'total of 40 CsF'eH: which has a boiling pointbyof the about 10-11‘ about 179 g. of crude organic products were colC. and a vapor density of about 6.97 g./1iter at ] lected. The following compounds have been 21° C. and 760mm. ' -'found in the reaction mass: CaFfeHz having a FREDERICK B. DOWNING. boiling point of about 10-11° C. and a vapor dens ANTHONY F. BENNING. J ity of 6.97 g/liter at 21° C. and 760 mm.; CHE 45 ROBERT C. McHARNESS.