... Mon, January 4, 2010 2:29:44 PM

... Mon, January 4, 2010 2:29:44 PM Richelle Fabellon From: ... View Contact; richelle fabellon To: fab.odt (22KB) 1 The present invention relates to a novel process for the chlorination of (perfluoroalkyl)benzenes, and is more particular!y concerned with a such process for the vapor-phase chlorination of a (perfluoroalkyl)benzene in the presence of an activated carbon catalyst impregnated with an inorganic chloride. Certain ch
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  ...Mon, January 4, 2010 2:29:44 PMFrom:Richelle Fabellon <>...View; richelle fabellon<>fab.odt (22KB)1The present invention relates to a novel processfor the chlorination of (perfluoroalkyl)benzenes,and is more particular!y concerned with a such process for the vapor-phase chlorination of a(perfluoroalkyl)benzene in the presence of anactivated carbon catalyst impregnated with aninorganic chloride.Certain chloro(perfiuoroalkyl) benzenes haveshown excellent heat-transfer properties,ceptional thermal stability, and excellent di-electric properties. One procedure previouslydescribed for the.preparation of chloro(trifluoïo-methyl)benzenes has involved chlorination of the-(trifluoromethyl)benzene in the presence of iron (III) chloride. This procedure is hot gen-erally applicable, and bis   (trifluoromethyl) bon-zones, fo mention one group, are hot effectivelychlorinated thereby. [See lïcBee et al., Ind.Eng. Chem. 39, 387-8 (1947).] Certain chloro- bis (trifluoromethyl)benzenes have, however, been prepared-by' a. procedure involving chlorination of xylene fo bis(trichloromethyl)benzenefollowed by ring chlorination and subsequentfluorination of the chloro-bis(trichloromethyl)- benzenes. Others bave been prepared by a pro-cedure involving ring chlorination of the xylene,then side-chain chlorination followed by fluor-ination- of the resulting chloro-(trichloro-methyl).benzenes. Chloro-bis (trifluoromethyl) - benzenes wtfich can be prepared, in this manner are limited to those .derived from correspondingchloro-bis(trichloromethyl)benzenes which arecapable of .preparation. If has also been im- possible fo prepare tetrachloro-bis (trifluoro-methyl)benzenes   in any. manner, prior to the present invention, and if is apparent that an im-   proved process for the preparation of chloro-(perfluoroalkyl) benzenes which would have gon-oral application would be highly desirable.If is an object oï the present invention to pro-vide a: novel method for the vapor-phase chlo-rination of- a (perfluoroalkyl) benzene. Another object of the invention is the provision of a such process' which is generally applicable in the preparation of chloro-(perfluoroalkyl)benzenes.A ïurther object of the invention is the provisionof a vapor-phase' process for the chlorinationoï .a (perfluoroalkyl)benzene in the presence of an activated carbon catalyst impregnated withan inorganic chloride. Other objects of the in-vention will become apparent hereinafter.The foregoing and additional objects of theinvention may be accomplished by mixing a   (perfluoroalkyl)benzene» in the vapor phase,with chlorine, in the presence of a catalyst2,601,310CIïLOIINATION OF (PEIFLUOIOALKYL)BENZENESEarl T. VIcBee, West Lafayette, Ind., and ItrvinR. Frederick, Wadsworth, Ohio, assignors toPurdue Research Foundation, West Lafayette,Ind., a corporation of Indiana No Drawing. Application June 1, 1948,Serial No. 30,5086 Claires. (CI. 260--651)2comprising activated carbon impregnated wihan inorganic chloride. Such inorganic chlo--rides are preferably iron (III) chloride oxtimony (V) chloride, although nickel chloride5 and other inorganic chlorides may also be em- ploYed.The (perfluoroalkyl)benzene may be heatedto ifs boiling temperature in a flask or other suit-able reactor, vaporized therefrom, and introduced10 simultaneously with or in admixture with chlo-fine, into a reaction zone   containing actïvatedcarbon impregnated with- the desired inorganic.chloride. Such a reactor may advantageously beconstructed of nickel or glass, and may be heatèd15 electrically fo a temperature above the boiling point of the desiçed chloro(perfluoroalkyl)ben-zene, so that-the chlorinated product may issuefrom the reactor, be collected by meanssuitable condenser and collection train attached  20 directly to.the reactor, and, if desired, passedinto a continuous rectiïying column. Alter-natively, the vapors issung from thechlorinationreactor may be passed through a water-cooledcondenser of nickel or glass welded directiy25 thereto, liquid returned fo the distilling flask through a liquid trap and the gases vented fo anappropriate scrubber.The starting material for the method of the present invention may be any (perfluoroalkyl)3o benzene, e. g.,   (perfluoromethyl)benzenes,fluoroethyl)benzenes, and the like. Bis(tri-fluoromethyl)benzenes may be ruade ïrom the.corresponding bis(trichloromethyl)benzenes byfluorination with anhydrous hydrogen fluoride,5 in the presence of antimony (V) chloride af about room temperature in accord with the pub-lication of McBee, Bolt, Graham, and Tebbe,J. Ara. Chem, Soc. 69, 947-50 (1947). Bis(penta-fluoroethyl)benzenes, 1 - (pentafluoyoethyl)40 (trifluoromethyl) benzene, (heptafluoroisopr6- pyl)benzenes, and 1- (heptafluoroisopropyl) .4-(trifluoromethyl) benzene may be prepared as de-scribed in the publications of McBee, Hass, Leech,Hodnett, Frederick, and Bonnet, Ind. Eng; Chem45 39, 395-7 (1947), McBee and Pierce; Ind. Efig.Chem. 39, 397-9 (1947), and McBee and Pierce,.loc. cit., 399--401, respectively. Partially ring-chlorinated derivatives of the foregoing are-also   suitable starting materials, and may be prepared50 in. known manner.The impregnated activated carbon catalystmay be prepared by soaking flnely-divided activated carbon in a. suitable liquid containing the particula, inorganic chloride desired fo be. ployed, and thon drying, as by heating601»310short period of rime ata temperature of about300 degrees centigrade. For example, an acti-vated carbon-antimony (V) chloride catalystmay be prepared by soaking activated carbon(8/14 mesh) in antimony (V) chloride andthen heating fo S00 degrees centigrade. Antivated carbon-iron (III) chloride catalystmay be prepared by soaking 200 grams of activatedcarbon in a solution of 60 grams of iron (III)chloride and 200 mfl]fliters of water made slightlyacidic with hych'ochloric acid. After soakingfor one hour, the carbon may be heated, e. g.,  ai about 300   degrees centigrade, to remove anyadsorbed water. Alternatively, the selected metalmay be intimately admixed with the activatedcarbon and the chloride generated in the admix-ture by passage of chlorine gas there-through.Other methods of preparing the catalyst aresuitable and will be apparent to one skilled inthe art.The chlorine which is introduced into theactor containing the activated carbon impreg-nated with a metallic chloride is ordinarflytroduced above the surface of the (perfluoro-alkyl) benzene being vaporized, and is carried withthe vapors of the (perfluoroalkyl)benzene intothe reactor, where chlorination occurs. Theamount of chlorine introduced should ordinarily be ai least one mole for every hych'ogen atomdesired fo be replaced with chlorine, inasmuchas one-half of the chlorine wfll be utilized inthe formation of hydrogen chloride. If is pre-   ferred fo use chlorine in excess of one mole for every atom of hydrogen desired to be replacedin the starting compound. The chlorine isvantageously introduced continuously with the(perfluoroalkyl)benzene in the vapor phase intothe reactor, and, if the product vapors are takenoff the top of the reactor, condensed, andcycled to the flask, more highly chlorinated products are thus produced. If, on the other hand, if is desired fo produce monochlorinatedcompounds, if is a simple matter to condensethe products from the chlorination reactor andfractionate the saine without a recycle. The tem- perature of the reaction zone wherein chlorina-tion is effected between the (perfluoroalkyl) ben-zene and the activated carbon catalyst impreg-nated with the metallic chloride is usually main-tained between about 150 and 300 degrees centi-grade and is ordinarily ai least as high as   the boil-ing point of the lowest-bofling chlorinated product.This factor is of some importance, inasmuch as, if the reaction temperature is not maintained abovethis point, clogging of the reactor may occtu'.The reaction temperature may be convenientlymaintained above the bofling point of the (per-fluoroalkyl)benzene, e. g., between about !50 and309 degrees centigrade, within vhich range thechlorination proceeds readily. The employment
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