March 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
rination, carried out in vessels connected in series of three, would have several advantages-for example, (a)more efficient utilization of chlorine, ( b ) automatic provision for a supply of mixed chlorine-hydrogen chloride gas needed in the early stages of the chlorination, and (c) elimination of the need for brine cooling on two thirds of the vessels. 4CKNOWLEDGMENT
The authors express their thanks to Raphael Rosen of the Office of Scientific Research and Devclopnrc,nt and to the Manhattan
319
District, U. S. Army Corps of Engineers, who helped in the guidance of this investigation and whose financial support) made it possible. The authors also wish to thank E. T. McBec. and associates a t Purdue University for mauy helpful suggestions. before t h e S y m p o s i u m o n F l u o r i n e C h e m i s t r y its p a p e r 7 4 , Division of I n d u s t r i a l a n d E n g i n e e r i n g C h e m i s t r y , 1 1 0 t h M e e t i n g of AJIEHICN CHKMIC.AL SOCIETY, Chicago, I l l . T h e work described i n this paper is coiered also in a comprehensive report of work with fluorine and fluorinated compounds undertaken i n connection a i t h t h e h I a n l i a t t a n Project. This report is soon t o be published as Volume I of Division V I 1 of t h e 1 I a n h a t t a n Project Technical Series. PnEqENTED
PILOT PLANT SYNTHESES Perfluoro-n-heptane, perfluorotlimeth~lc~clolmexane, and high boiling fluorocarbon oils W.B. Burford 111, R . D. Fowler. J. 31. Hamilton. Jr.*. H. C. -Anderson?.C. E. Weber3, and R . G. Sweet4 T H E J O H N S HOPItIhS U N I V E R S I T Y , B i L T I \ I O R E . \ID.
THE design, construction, and operation of a pilot plant for the production of perfluorocarbons b?;the CoFt process is described in detail. The process consists of passing \aporized hydrocarbon oyer CoF3 poi+der at suitable teinperatures, after which the resulting CoF, is regenerated with elenientary fluorine. The reactors, fluorine cells, disposal system, and recovery systems are described i n detail, and t?-pical operating characteristics are outlined. A flow sheet shows schematically the interconnection of the various units. A brief description is included of the ventilation system for the plant, operating personnel required to r u n it, and normal output. Physical properties of some typical perfluorocarbons produced by the unit are included.
H E S it became evident that perfluorocarbons could be made readily by the CoFz process developed by Fowler and co-workers (3) or by the direct fluorination proces? of Grosse, Cady, and co-workers ( I ) , the demand for experiniental scale production became very great. A pilot plant K : L ~therefore set up a t ,Johns Hopkiris to produce materials ranging in hoiling point from that of perfluoro-n-butane (ahout - 2 " C.) to that of an oil boiling over 350" C. Development of pilot plant scale equipment ~va; undertaken before the laboratory inrestigntion ivaq conipletetl. and thiq fact, together n-ith the novelty of the CoF3 process. deiiianded design on the basis of very limited infornration. mthesis of perfluorocarbons is a tn-o-step cyclic procpss:
+
~ C O F ? F? +2CoF3 -CH2-
+ 4CoF3 --+ -CFZ-
+ 2HF + 4CoF2
I n addition to substitution of hydrogen in -CH2-CoF3 will also add fluorine to multiple bonds:
CaH6 $- 18CoFa ---+ GFi2 1 Present t o n , Del. 2 Present * Present 6 Present
(1)
(2)
groups, the
+ 6HF + 18CoFz
address, E. I . d u P o u t de S e m o u r s & C o m p a n y , I n c . , Wilmingaddress, Socony-Vacuum Oil C o m p a n y , Paulshoro, N. J. address, General Electric C o m p a n y , Schenectady, N. Y . address, Linde Air Products. Tonawanda. X. Y .
T o adapt such a two-step cycle to a continuous operation, the time periods for each step of the cycle must be approxim:ttely q u a l . Since the heat evolution governs the feed rate of fluorine in the first cycle and of hydrocarbons in the second, and since it has been shown (3)that the heats of reaction of the two step- :ire about equttl, it should be possihle t o carry out each step in a h o u t the same length of time. In practice this vvas verified. B further requirement for continuous routine opcrntion n-a.: that the necessary inert gas sweeps (which followed earh htep, for the purpose of removing excess fluorine in step OIIP and hytlrogen fluoride and product, in step tvio) fit into a vmrkatil~tinir srhedd e . The sn-eeping period could also be utilized for tenipernture adjustment, since each step was carried out under tlifferent temperature conditions. .I sn-eeping time equal to 11:df the time required for either step \\-as found suitahle, -inre it permitted easy siniulta~ieous temperat,ure adjustment. Generally two hours were needed for each step, n.ith n one-hour pei,iod of sr\-eeping folloiving each step. It was therefore nossible to the l)est insulating material tested hut ims not capable of long 1); the graphite and asbestos packing \vas thus protected, and zervirc iit high temperature. The combined effects of high voltthe small amount of additional nitrogen introduced in this nianage and temperatures in excess of 350" C. resulted in charring ner could not be noticed in operation. DUST PRECIPITATOR^. This unit deserves special mention, arid ultimite electrical hreakdon-n along the surfare of the cylindP1.. since Lvithout, it operation v a s almost impossible during the hydrocarbon feed as a result of plugged outlet lines. T h e total I~I;.ICTOR LIFE. The life of the reactor vas primarily governed outflow of gas from the reactor was approximately 45 liters per liy the rate of erosion of the shell, paddles, exit tower, and therniocouple wells. The diel1 and thermocouple \\.ells were found to minute, feeding heptane a t a normal rate (exit temperature, 375have tlie shortest life, n-hich was dependent upon the cheniical 400" C.). This high gas velocity entrained considerable powder, nature of the ponder and the temperature a t ~ h i c hthe reactor particularly v h e n the charge was old and had been ground to a vxs operated; tlie paddles, although less affected, shon-ed signs fine dust, and it n-as esfential that this poivder he prevented from of n-ear after extended service. The life of the exit towers waa reaching the disposal or condensing systems. ~ factors since they n'ere n o t in contact with governed I J otlicr The precipitator, shon-n in Pection in Figure 6, consisted of a steel rod, 24 inches long, extending don-n the center of the exit the Inn-der. Reacators clinrgetl with CoF3,in general, outlasted those charged tube, 15-ith a short wire extension a t the bottom to serve a? a n n.jtli hInF3 ivith re.;pect to shell and therniocouple n-ells. The iopizer. This entire electrode was maintained a t 12.000 volts forinel, tended to form a protective cake on the interior metal with respect to the shell, ~-1iichn-as grounded. part>. preventing Huorine from reaching them and minimizing The action of these dust precipitators ivas extrenirly good, tlethe scouring action of the powder. On the other hand, N n F 3 spite thei.r tendency t o become n-et with high Iioiling reaction products n-hen heavy oils were fluorinated. With the precipidid not cake, anti the result n-as more rapid n-ear. K i t h CoF3 and IIIJ\- temperature operation (150-300' C.) the tator the loss of pov-der v a s cut to 27, of that n-itliout it, and the efficiency did not fall off measurably during the run. Hon.ever, > t a n d u d half-inch ahells and standard thermocouple. lasted if used in connection with high boiling materials, the precipitating Iiiore than 18 months; ~ v i t hhigh boiling feed stocks and operatunit required cleaning after each hydrocarbon feed step, to clear ing teniperatures betiveen 360" and 430" C. this was retluced to it of the cake of precipitated dust adhering to it. With lon boil:ibout 6 months. With ?*InF3these periods of uieful servire were ing feed stock, the precipitator was dry a t all times and n - a i -elfreduced by a t least half. Because of their massive construction cleaning, the cake merely dropping into the reactor of its own and the cooling effect of the hollow shaft, the agitating paddles weight. did not require replncement during the entire period of operation, It was not customary to use a precipitator during tlie fluorinan-hicli \vas a little over 18 months. The outlet tolvers were not tion step, since there was only a small volume of gas coming from iubject to attack a.: a re,et the flask in a copper tray to avoid 10s. in the event of accidental breakage of the glass. The condensing system, as well as the hydrogen fluoride itorage tank, T m s cooled by diverting a portion of the cold methylene chloride uied in connection n-ith hydrogen fluoride renioi-al from the Wuorine and hydrogen from the cells. Thi? w:is circulated t1irouF.h coil^ and regulated by conventional tempcrztture controls. Crude perfluorocarhon, consisting of the de5ired mzterial as well as some lighter degradation products and some heavier polymerized product., all essentially completely .uh-tituted, was comhined (it' tn.0 condensers had been used) and \v:~.lied several times nitli dilute caustic. It was then purified in :I routine lahoratory by wnzhing to remove caustic, separating tile water, and filtering, and x t s then ready for distillation. .Ay a rule drying i v ~ i qunncc.ewary tiecause of the iiegligihle soluhility of water in t h e mutcriuls. In some cases, hoivever, ivhere the boiling point of the de-ired compound lay very clwe t o tli:it of water, drying Tvith anhydrous sodium sulfate was desirallle. For fin:il purification, recourse was had to rli.till:ition :is tlie only \ ~ ~ r k a kmeans ) I ~ of separating by-products from the material ~ chemical means had proveti inadequate. clesired, uince v : i(iu. The desired purity determined the care with n-1iic.h tlie samples were fractionated, hut for a large portion of tlie work here, a forty-plate column ]\-as found to be adequate and to provide purities in the neighborhood of 95-99%.
INDUSTRIAL AND ENGINEERING CHEMISTRY
March 1947
VENTILATION
The corrosive nature of fluorine and hydrogen fluoride, as well as the extremely unpleasant effects upon personnel, made it necessary t o provide adequate ventilation t o all working areas in the plant. In addition, there was tlie problem of a large quantity of waste heat from the apparatus, despite the chimney; and vents. The presence of hydrogen fluoride and)'or fluorine i n the atmosphere of the plant was quickly noted because of the extremely low threshold of nasal perception, 5-6 parts per iiiillion. The principal sources of atmospheric contamination were leak5 around the cell heads, leakage of valve packing.;, and operating difficultie? resulting in release of gas t o loxver the pressure in any part of the system. Specialized ventilation was theiefore provided for all point? ivlierc .uch leakage was frequent. In tlie cell rooin. the exhau-t equipnlent \vas arranged to provide a high speed Gtream of air aero.;.; each c r l l , away from an operator standing in front of them or the valve hoard., so that hydrogen flucii,ide o r fluorine was taken into the exliauyt duct before diffu-ing into the room. Tlie syhteni ninintaiiied an air velocity of 1500-1600 ieet per minute and a n air motion of 1000 cubic feet per niiiiute :~cro?$tlie cell into an openiii,rr just heliind the cell lienti. l h i c arrangement wa. highly succe-.tu], and t h e air motion, froni tlir air supply in the center uE t h e room don-nward acrn..? e:icii cell. reduced operating diw)nifot~tto n niinimum. Another exnniple i q furnished by the reactor room, n-here input ducts were ai~rzang,.etlover each control panel, at the iiilet end of each reactor v-here an operator regulated tlie f l o ~ r -of giis into tlie reactor, and a t the nutlet cf each reactor near the top of the ton-er where an oprratnr o r mechanic worked on the high voltage unit
M~IN ZLECTRODE
. ~ JOUER r
. ROD
Figure 6.
Dust Precipitator
( T F E = Teflon)
IONIZER
327
or regulated the f l o of ~ gas away from the reactor. This system provided that cool inlet air first reached areas where men normally worked, and kegt such work space essentially frer from contamination by toxic and unpleasant gases. The problem of waste heat disposal, particularly in warm Iveather, proved to be serious, since the plant consumed approximately 50,000 cubic feet of illuminating gas per 24 hours, and 4nce the units operated betn-een 260" and 450" C. There was a ~.onsiderableamount of radiant heat, despite heavy insulation, \r-liich was aggravated by the small physical dimensions of the plant. During the fir.it summer of operation, teniperatures in the operating areas on the second level of the reactor room frequently n-ent as higli as 60' C. The general ventilation, therefore, was designed to provide a one-minute air eliange in tlie reactor room h s means of n large duct, running tlowi the length of the room close to the ceiling a n d removing 25,000 cul)ic feet of hot a i r per minute. T o balance thi;, in t h e reactor room the input 1:m delivered about 12,000 cuhic feet per minute to specified location- as outlined, n.hile the remainder of the air \vas brought in through windon-. nlonq one -ide nf the reactor rnotn. This techilique wccesifull\- controlied the icmpi1r:itur t' rli t lie nwrking :tress and Ion-ei,ed the geiieixl or t i i w i i t ( , i i i ! w x t u i c> to atio11t 37' c. PERSOZNEL
.In adequate estimate of the iiiinirnuni ~ i ~ t ~ . ~ i i ~iquirecl tii~I to iiperate this pilot plant is difficult, for tlii~on'chc~ut it.. existence the unit maintained a rigorous productiiln ~clietlulearid also made many experimeutal runs. The >taff of -eveiitren desxilied here i i based on operation during a so-called iioriii:d period, \$-lien no niajor structural c1l:tnger \\-ere being iiiade, expc~rinientnl{vork was at a minimum, and adequate materials w r e on hand for replacement parts. In actual practice, the operating and nmintenance staff usually numhered about thirty, :tnd thr majorit>-of the extra nien n-ere mechanic. and shop n-orker; to take care of redesigning, etc. The entire plant \vas in charge of an cx:!)ei.ienced research chemist, n.itli a junior engineer as a tant. These men laid out the operating schedules, and \\-ere directly reqmnsihle for all aspects of production, experimental ~ r - o r k ,miintenance, and requisitioning of supplies as needed. They Tvwe in charge, directly or indirectll-, of fifteen nonprofrwionul workers, who were divided t o cover t'he entire day. Each shift as composed of a .-upervi-or and tn-o chemical operator?, nile of whom was responsible for the cell rooni, while the other operated the reactors, the caustic disposal unit, arid the pre1inh:try vr-ashing of the crude product. Tlie duties of t'he cell-room antl tlie react,orroom operators included in;pection and minor miintmance of the lo~vvoltage generators and refrigeration s?-;tcm. The supervicoi's duties consisted primarily of kreping .:ati-factory plant record5 in the form of log sheets, checking the ope] atorr, and reporting t o the maintenance staff any faults requiring attention. Tn-o men on the day diift were requireti to make repairs and replacements of worn out units, and were nance mechanics. Working xvith them iva.5 an-elder who could do all types of welding, silver soldering, and brazing. These three inen were able to maintain in operation all the units regularly engaged in production, but !?-ere not adequate i f any major change5 lvere contemplated. In addition, foi the fabrication of parts and miscellaneous machine work, at 1es.t tiyo nien in the machine shop were conzidered to be chargeable to the operation of the pilot plant. The crude product, as delivered from the plant to the laboratory, had t,o be neutralized, washed, distilled, etc.. before it could he shipped as specification grade material. One >killed teclinician, in a suitably designed laboratory, could take rare of this for production runs. Special runs antl very precise fractionations were handled by a chemist outside the routine 1a.horatory.
INDUSTRIAL AND ENGINEERING CHEMISTRY
328
Vol. 39, No. 3
3 '%, perfluoroetli3-lcy.clopentane 8 % ; 1)erfluoro-n-heptane 87%; p e r f l u o r o Yield polymers 1yo. of P u r e PERFLUORODIMETHYLCYCLOHEXASE Product, Boiling 5% RFna;e, This material was produced from bis(SinglePass) C. [trifluoromethyl)benzene furniehed by b Ahont - 2 58 2 - f . 4 - 2975 the Hooker Electrochemical Company; 28 23.5- 23.7 the yield data demonstrated the high 38 71.5- 71.8 59 75.1- 75.2 stability of a partially fluorinated niole77 76.3- 76.4 42 102.1-102 4 cule, in comparison with a pure hydro50 101.7-101.9 carbon. In contrast to the results ivith h e p t ' a n e , bis(trifluoromethy1)benzene gave crude yields up t o 97%, and 88% of pure product, based on the feed. The boiling range of the resulting fluorocarbon, which was known to be a mixture of isomers, was 101.0' to 101.8' C. The refractive index was about 1.290, depending upon the Composition, and the density about 1.86. The principal byproduct isolated was perfluoromethylcyclohexane, resulting from a process analogous to demethylation. This mat,c,rial s-as by far the easiest to handle of all feed stocks employed during the history of the plant. There was less heat of reaction (and consequently, easier temperature control), larger quantities could be fed to a reactor during a single run, und there was little or no tendency towerd the production of high boiling by-product, which minimized CoF3 contaminatioii and line plugging. PERFLUORO SOLVENT.Three thousand pounds of a light perfluoro oil, t o be used as a solvent in contact with highly corro4ve chemicals, were produced starting with a high boiling kerosene cut. This starting material was known as X C T White Oil (obtained from the Standard Oil Company of Pennsylvania). ' h e 701vent specifications called for a reflux boiling point nhove 180 C. and an upper limit to the boiling range of 147" C. at 10 mrn., as \yell as other requirements as t o reactivity, etc. The st,arting oil boiled in the neighborhood of 250-300 O C. and represented the
TABLE I. TYPICAL PI-REC o m o r - s w PRODTTED
Starting lIaterial
Crude I-ield,
Pure Product
%
n-Rir tnne .
np -Perfinorti-n-hiitn . __._...
4. 5.a
n-Pentane Cyclopentane Dimethylcyclopentane Ethylcyclopentane Benzotrifluoride o-Xylene n-Xvlene
Perfluoro-n-pentane Perfluorocyclopentane Per5uorodin1ethylcyclopentane Perfluoroethylcyclopentane Perfluoromethvlcvclohexane Perfluoro-o-dimefh ylcyclohexane Perfluoro-m-dimethvlcvclohexane
67 46" 83 68 88 63 66
~
a
Large handling losses.
b
h-ot distilled here.
TABLE 11. PHYSICAL PROPERTIES OF CERTAINPIXE COMPOVKDS
Pure Product Perfluorodimethylcyclopentane Perfluoroethylcyclopentane Perfluorometh ylcyclopentane Perfluoro-p-dimethylcyclohexane Perfluoro-m-dimethylcyclohexane Perfluoro-o-di methylcyclohexane Perfluorohexahydroindan Perfluoro-1,3,5-trimethylcyclohexane
Refractive Index 1.2765 1,2772 1.2815 1.2897 1.2908 1.2923 1.3077 1.2995
Density 1.7660 1,7707 1.7994 1.8503 1.8560 1.8672 1.8948 1,9025
durfnce Tension
.. 15:4 16.3
..
..
..
..
S o t included are such itenla a- r l i o ~fureriiun's ~ time, and zecretarial and clerical help on the pay roll, purchasing, and other service departments. These could not be directly charged to the operating cost of the unit as it was organized here, and no e 4 mate is therefore attempted. PUREPRODUCTS
Table I lists a few of the pure materials TI-hichwere produced and purified during the course of the plant's operation. The yield figures given are for single pass through the reactor; they do not reflect optimum yields since, as a rule, only a few runs were made and partially fluorinated material as not repassrd to obtain more of the pure product. Table I gives the range of boiling points for these materials. Talile I1 li,ts other physical properties for the compounds n-hirh were studied more exhaustively. More complete data and other characteristics of the pui'e compounds are presented in the other papers in this symposium from this laboratory; from them these figures were taken. The material is included here primarily to demonstrate the versatility of the process and the Tide range of its applicability to the production of perfluoro compounds.
Only a few pounds of the pure compounds were made for purposes of technical study. However, considerable quantities of other materials were turned out by this plant on a straight production basis. PERFLUORO- HEPTANE. This material was prepared from pure n-heptane, as furnished for automotive knock-rating tests by the JVestvaco Chlorine Products Corporation. Several hundred pounds of pure material were prepared, with crude yields averaging about 907, and a yield of pure product, based on the hydrocarbon fed, averaging 7 5 4 0 % . In this case pure product refers t o a colorless fluorocarbon boiling between 82.4" and 82.6" C. and meeting certain specifications as regards chemical reactivity. The average refractive index of this material was 1.262, and the density 1.733. The typical composition of crude perfluoro-n-heptane from an exhaustive fractionation in a ninety-plate analytical column follows: perfluoro-n-hexane 1yo,perfluorodimethylcyclopentane
E
-D
PRODUCTION MATERIALS
-4-L
L-c
/
M A . Thermocouple B . Thermocouple well
D. Vapor outlet Oil inlet
I.
E.
Packing r l a n d
Vaporizing chamber R. Weld L. Xtrogen Y W ~ P M . Heater chamber
J.
F. G. H.
C.
Figure 7. Hydrocarbon Vaporizer
Head n u t Gasket Hex for wrench Vaporizing plate
March 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
first production of a high temperature type, demanding that the reactors be in the neighborhood of 300" C. at the inlet end. These higher temperatures resulted in a proportionately decreased crude yield, and the average fell to about 70%, based on to -CFs--; the average composition the conversion of -CH2of this crude is shown by means of typical diitillation data: Boiling R a n g e 20Sc C. (10 m m . )
% of Still Charge 15 45 36 4
329
ii typical specification cut of this material had n viscosity of 980 Saybolt seconds at 37.8" C. and 57.2 seconds a t 98.9". Yariations in feed stock did not benefit the total production per run, despite the rather high percentage of the crude which lay outside the desired distillation range, nor was it possible to increase the crude yield significantly by variations in the operating technique. Severtheless, approximately 2800 pounds were produced lyithin the stipulated specifications, and the lighter byproduct' cuts found application as solvents. ACKNOWLEDGMENT
Only 45% of the material corresponded to specification grade solvent. Although it n-as possible to increase this figure significantly by changes in feed stock, this was not done, as the fraction boiling in the range 147-208" C. a t 10 mm. was equally desirable as the lubricant described in the following section. PERFLUORO LUBRICANT.The highest boiling fluorocarbon produced in quantity by this unit was fluorina,ted lubricating oil having an average molecular n-eight in the neighborhood of 1000 which corresponded to a chain length of about 20 carbon atoms. This material boiled from 147" to 208" C. at 10 mm. although it was frequently possible to blend in higher boiling and lower boiling materials and still meet the viscosity specification. The increase in molecular n-eight was again reflected in the higher boiling point of the starting material (325-410' C.) and the necessity for operating the reactor entirely above 350" C. The most common starting material was an SAE 10 lubricating oil known as Diol 45 (made by the Standard Oil Company of New Jersey). The crude yield with this material fell to about 50%, based on A typical distillation the conversion of -CH2-- to -CF?-. analysis follo\\-s: Boiling R a n g e
% of Still Charge
208' C . (10 mm.)
23 24 4;
This paper represents Jyork done for the U.S.Army Corps of Engineers, Manhattan District. R. Rosen and E. T7. Rlurphree of the Standard Oil Company of Xew Jersey were instrumental in getting the pilot plant 15 ork started. Much profitable knowledge was derived from contact with men of the Du Pont Company, particularly H. W. Elley, -2.F. Benning, F. B. Downing, J. D. Compton, W. 0. Jewett Jr., and J. B. Roberts. The interest of D. H. Andrew in the early work of R. D. Fowler on the preparation of fluorine and UFs led directly to the work described in this paper; the interest and generous financial rupport of H. A. B. Dunning made that early work possible. LITERATURE CITED
(1) Cady, Grosae, Barber, Burger, and Sheldon, IND. ENQ.CHEM., 39,290 (1947). (2) Fowler, Burford. Anderson, Hamilton, and Weber, Ibid., 39, 266 (1947).
(3) Fowler, Burford, Hamilton, Sweet. Weber, Kasper, and Litant, I b i d . , 39,292 (1947). PRESENTEDbefore t h e Symposium on Fluorine Chemistry a s paper 6.5, Division of Industrial a n d Engineering Chemistry, 110th Meeting of the AMERICAN CHEMICAL SOCIEI'Y,Chicago, Ill. T h e work described in this paper is covered also i n a comprehensive report of work with fluorine and fluorinated compounds undertaken i n connection Ti-ith t h e Alanhattan Project. This report is soon t o be published a s Volume I of Division V I 1 of t h e M a n h a t t a n Project Technical Series.
FUuorocarbons by fUuorination of hydrocarbons with
COBALT TRIFLUORIDE
THE eflects of Tariables in the fluorination of R. G. Benner, A. F. Benning, F. B. Downing, n-heptane and diperfluoromethylbenzene with C. F. Irwin, K. C. Johnson, A. L. Linch, cobalt trifluoride were determined. The most H. M. Parmelee, and W. V. Wirth suitable method for purification of the E. I. DU PONT D E NEMOURS & COMPANY, INC., WILMINGTON, DEL. resulting perfluoroheptane and perfluorodimethylcyclohexane was fractional distillation. Measurement of the dielectric constant of the further with the object of determining the effect of operating crude and distilled products proved useful as a means of variables aS well as developing methods of control and analysis. controlling quality, whereas infrared methods were relied The high heats of reaction in both the fluorination of hydroon for final analysis of the purified product. carbons with cobalt trifluoride (Equations 1 and 2) and the conversion of the resulting cobalt difluoride with elemental fluorine (Equation 3) complicated the production of the fluorocarbons on fluorocarbons ere first prepared by Simons and a large Block (4) by the action of fluorine on carbon black. Cady and co-workers (1) made fluorocarbons by fluorination of hydroc , H l s + 32CoF3 C,Fls + 32CoF2 + 16HF + looo kg.-cal. carbons with eIemental fluorine over various catalysts. Fowler /I\ \'I and associates ( 2 ) fluorinated hydrocarbons indirectly R-ith cobalt trifluoride; the cobalt trifluoride was converted to the difluoride, which was then reconverted to the trifluoride with fluorine gas. The purpose of this work was to develop processes for the large 14CoF3 CsFla 14CoF2 4HF 460 kg. cal. scale manufacture of perfluoroheptane and perfluorodimethyl( 2) cyclohexane. The method developed and demonstrated on a semiworks scale by Fowler et ai. appeared the most suitable for large scale manufacture. A4ccordingly,this method W M studied 2CoF2 FB 2CoFa 58 kg.-cal. 3)
-
+
+
+
-
+
+
+
+
