INDUSTRIAL AND ENGINEERING CHEMISTRY
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ments of the extent of hydrolysis with dilute alkaline solutions. The tests were carried out at, 100" C. with vigorous stirring, and a t the end of the test the liquids were separated and the fluorocarbon was washed several times with distilled rr-ater. These washings viere combined ivith the original aqueous phase and the fluoride content determined as micrograms ( y ) F- per milliliter of fluorocarbon. I n practice each sample was subjected t o a number of AUCCCSsive 4-hour hydrolyses a t 100" C., the aqueous layer consisting alternately of l Vo sodium bicarbonate and ZOyc sodium hydroxide. T h e fluoride ion content of each bicarbonate hydrolpis was determined and the series continued until successive values showed no significant change. The general trend of successive bicc'artmmte hydrolyues on a highly purified sample of perfluoro-n-1icpt:inc. is illustrated by the following example. Here, as described prcviously, the sample was subjected to a 4-hour vash Ts-ith 20"i GOdiuni hydroxide between bicarbonate hydro1 ?i-heptanc had a b.p. of 82.52-82.55" C. HCOI-
Hydrolysis
1 2 3
y
F-/1II.
Fluorocarbon 299.0 41.0 6.0
Hydrolysis
-,' r -/ 111. Fluorocarbon
4 5
0.5 0.7
HCOC
Tests were also made on perfluoromethylc-clohexane and the three perfluorodiniethylcycloliexanes x i t h similar results, but in the ease of p~~rfluoro-l,3,d-trini~thylcyclohesane, reaction with sodium hydroxide \\-as incapable of reducing the values for liicarbonate hydrolysis. This behavior suggested that the sample lva.5 not properly purified, since it v a s typical of the impure fluorocarbons tested; it might have indicated hydrolysis of the pure material itself, KO conclusions as to the nature of the impurity in the normal
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case could be drawn. I t is possible to say, however, that this impurity exists even in the most carefully distilled samples, and, once it has becn removed by other means, the remaining material gives little evidence of hydrolysis under the condition. of these experimenthe addition of each 100-gram portion, the tube was heatcd to 00' and cooled again t o 0" C.; thus a n accumulation of unreacted perchlorobenzene was prevented in the reaction mixture. After 400 gram3 of perchlorobenzene had been added, additional bromine trifluoride (244 grams) was introduced sloivly and 260 TABLE I. EFFECT O F REACTAXT RATIOS grams of perchlorohenzene were then added; the final reaction Reactants, Moles Dehalogenated Products, % ratio was 3 moles of bromine trifluoride t o 1 mole of pcrchloroBrFa CsClj(CF3) CeFs(CFa) CeClF4(CFa) CeCIsFa(CF3) Cd?hF2(CF)3 20.0 24.3 8.0 3 1 11.6 henzene. The reaction mixture was heated for 12 hours at 22.7 20.8 2 5 1 2.0 17.4 21.9 25.5 14.2 2 1 2.2 1.30" C., and the molten product poured into a copper pan vihere a red-brown solid formed. TT-hen this solid n-as pulverized, bromine vapors e;caped, leaving 1025 grams of a n-vhite solid. Since perfluorohenzene and perfluorotoluene were desired, anportion of the solid r a s recrystallized from ethanol and found timony pentafluorine \vas used to replace some bromine with to correspond approximately to a misture of average composition fluorine at temperatures lielo\v about 120" C',, so that, upon deC'6BrPCliF6. halogcnation, chlorine would be reniovid and fluorine would The material from the bromine trifluoride fluorination (1023 rciiiairi o n the ring carbon atoms. If much I)romine had hecn grams) \vas dissolved in a fluorochloro compound, and thc solution left in the molecule, dehalogenation n-ould have, removed broheated to 60' C. in a 2-liter flask x i t h constant stirring. Antiminc and left chlorine. In no case was: all of the broiiiine rt.placetl, mony pentafluoride (300 grams, 2.3 molcs) was added dropwise as the conditions required n-ould probably also have rewltcd in over a 3-hour period, evolved bromine heing rccovcrcd. The rtiplucenient of a portion of the chlorine; for dehalogenation, it reaction temperature v a s then raised t o 100" C,, where hromine possible on the ring i v a ~pwferable to retain as much chlorin and part of the solvent distilled from the reaction mixture. All carbon atoms. of thc solvent \vas then removed. and a n-hit,e solid product reThe final step in the process, that of dehalogcnation, \vah acmained x i t h an average composition C'cBrC:l,Fr. coiiiplished with zinc suspended in a suitablc inetlium such as The x-ashed product from tho reaction v i t h antimony pcnrawater, ethanol, or acetamide. Factors influencing the dehalogenafluoride \vas dissolved in 500 nil. of absolutc ethanol, and the wtion n-ere composition of starting organic material, reaction sulting solution !vas added during a &hour pcriod to a \vcllmedium, dehalogenation temperature, weight ratios of the orstirred suspension of 500 gram? of zinc dust in ethanol at reflus ganic material t o zinc, and viscosity of the reaction mixture. temperature. 3Iore volatile products distilled from the niisture Starting material containing an average of about 6 fluorine atoms along with some ethanol, and higher boiling coristituents \vcre reor less on the ring dehalogenated sonieivhat' easier than material moved by steam distillation. .llcohol vas removed from thc cont:iining fluorine atoms in ex is number. .Icctamide products by washing v i t h Ivatcr. The total halocarbon product and water did not allow as high of products as did ethaweighed 509 grams (yield, 53y0 based upon starting pcrchloronul, but increawd j-ields of lowe products ~ c r obtained e benzene). Products obtained by rectification were pcrHuoron-1ic.n acctaniide \\-as the medium. This was cyclohexadiene 55 grams, perfluorobcnzcne 23.4, chlorohepta1iighc.r rcaction temperatures which n-erc po esadieiie 81.4, dichloro-octafluorocS-cl(~liexerie55.3, a m i d e medium, as the elevated temperatures fluorocycloliesadiene 37.8, trichlorolieptafluorocycloof more highly unsaturated compounds. Dehalogenations were hcsene 28.2, and trichloropentafluorocyclohexadiene 20.4. Table friquontly carried out in ethanol and intermediate fractions then I1 gives physical constants and anal!-ses of the compount1.i dehalogenated in an acetamide medium. -1decrease in the quanprepared from perchlorobenzene. Dehaloeena.tions in a followxl a procedure siniilar t o that of IIasr, LIcBee, Hinds, OF BESZESE AND TOLUEXE TABLE11. DERIVATIX-ES and Gluesenkanip (f 1. I n one Boiling Point i~~lti,,~ 5; c1 RF Mol. wt. instance 1026 grams of a haloFormula C. 3 I m . Point, O C. ?lao d22 Calcd. Found Calcd. Found Calcd. Found BESZESE carbon mixture having the avcrCEFS 56.0-57.0 743 +6 1.3149 1 . 6 0 1 0 . 0 0.0 67.8 67.9 2 2 4 . 0 223.0 age composition CaBr,.5C13.6F, CaFa 81.0-82 0 743 - 1 3 t o -11 1.3760 1 612 0.0 1.1 61.4 60.7 186.0 189.0 1.3660 1 . 6 3 3 1 4 . 8 1 3 . 8 5 5 . 3 56.6 240.5 2 4 1 . 0 c~C1Fr 88.0-89 0 740 - 6 0 t o -65 were dissolved in 100 ml. of diCsClrFa 112 5-113 5 750 -70 1.3748 1 719 2 4 . 1 23.0 51.5 53.5 295.0 2 8 6 . 0 ethyl ether, and the solution was 1.4030 1 . 6 5 6 2 7 . 6 2 5 . 2 44.4 45.6 257.0 250.0 CsC1rFs 119.0-120 0 750 - 2 5 t o -30 CsClFs 122.0-123.0 750 1.4256 1.568 1 7 . 5 1 6 . 1 4 6 . 9 45.4 202.5 200.0 added with stirring during a 12750
