348
INDUSTRIAL AND ENGINEERING CHEMISTRY
chlorine atoms, as illustrated by reactions 13 to 17 (Table 11). Reactions 13 through 16 n-err carried out in thc vitpov pl~aic.; 17 was run in the liquid phase under rvflux. Ilrl:iti\~rly lwgc increases in density after cobalt fliioridr treatmc~iit n-ere found with some antimony fluoride producti. Thrl?e are bclicvxl to be due mostly t o addition to double bonds by tlie reagmt. Evidence as to the structure of the products of rc:iction+ 13, 11, and 15 is not a t hand, but the niechanism of cyclization postulated above suggests that these are derivatives of cth?-lcyclopcnt:ine. LITERATURE CITED
(1) Benner, R. G., e t . al., IXD. EXG.CHmr., 39, 329 (1947) (2) Benning, A. F., U. S. Patent 2,230,925 (Feb. 4, 1941).
Vol. 39, No. 3
(3) Dsudt, H. I”., nnd Touker, 51. .I., I M . , 2,005,710
(.June
18,
1935). (4) Henne, -4.L., and Midgley, T., Jr., J . Am. Chem. Soc., 58, 884 (1936). (5) Hcnne, A. L., and Nemman, M. S., Ibid., 60, 1697 (1938). (6) Prins, H. J., dissertation, Delft, 1912; J . prakt. Chem., 81, 414 (1914). ( i )Prins, H. J . , Rec. traa. chim., 51, lOG5 (1932). ( 8 ) Ihid., 57, 659 (1933). before the Syuiponiurn o n Fluorine Chenli.try a i pnper 7 5 . Division of Industrial a n d Engineerinp C‘hemistry, 110th LIeeting of the . ~ \ I E R I C . ~ PC H E \ l I C . 4 L S o C I E . r Y , Chicago, Ill. T h e work described in this paper is covered a l ~ oi n n coniprrhen~irereport of work with fliiorine a n d fluorinated compounds undertaken in connection with the l l n n h n r t n n Project. This report is s m n t o be published as 1-olume I of Division \-I1 of the M a n h a t t a n Projert Terhnical Series. PREsEUrEo
(PREPARATION OF CHLOROFLUOROCARBONS)
RUuorination of poUychUoroterphen yUs F.B. Stilrnar, W. S. Struve, and W.V. Wirth E. I. DU PONT D E VEMOURS & COMPANY, INC., WIL1lINGTON, DEL.
CHLOROFLUORO oils can be made from heavily chlorinated aromatics with either AgF2 or ShFj. Economy in the elemental fluorine requirement is demonstrated orer the hydrocarbon-AgFg process. Although the resulting chlorofluoro oils are stable compounds, they do not haye the thermal and chemical stability of the perfluoro oils. The fluorination of highly chlorinated aromatics with AgFz or SbFs appears to he general. Preliminary indications are that certain nitrogen and ovygen linkages survive fluorination.
fluoro oil production over fluoro oil output amounts to 70% per unit of AgF, instead of 85% as implied by the above equations and yield data. A furtl1r.r saving in active fluorine results when a halogenated HF). hdditcrphenyl is first rcacted with SbFa (from SbClb tion as well as substitution occurs, and t,he resulting chlorofluoro oil can tic completely halogenated with only two parts of AgFz. This saves more than 70y0of the AgFg needed for the conversion of the chlorinated terphenyl directly to chlorofluoro oil. The steps may be represented as:
C
(mol. vt., 713)
HLOROFLCORO compounds have been preparcd that are
comparable in stability with the perfluorinated oils discussed in the third and fourth papers of this series (pagcs 350 and 352). -4 number of heavily chlorinatrd polynnclcsar compounds yield chlorofluoro oils, either directly with .\gFn or ivith 8hFj followed by a sniaI1 amount of AgFz. Such products arc. most readily prepared from either chlorinatcd 0- or m-terphclnyl. The advantage of preparing a chlorofluorocarbon rathw than a fluorocarbon oil lies entirely in the minimum use of elcmcntal fluorine. Equations 1 and 2 illustrate tlic comparative amounts of .4gF2 required in each of the conversions:
c1
+27.igF,+
c1
>CH*]
-
+ 72.W‘~
I
I
ClsCI1,
+ 18SbF6--+ (product containing 22’% Cl)
(product from Equation 3)
(3)
+ 14AgF2 --+ ClsCi~F~~(15.9% CI) (mol. wt., 800) (4)
The over-all yield is 60% of theory, according to this i,cprcacntation. CHLORINATION
The chlorinated starting materials containing G7-G!)C; C1, were obtained in quantitative yield by passing clilorine into 0- or m-terphenyl a t 200-300” C. in the presence of lC; FeClr (theory, 60.7q chlorine for Cl&l14). The clilorinntetl material TTRS fluorinated directly. Further Cl8C1,F2,+ 27AgF + O(C1) (1) chlormntion n l t h ShC1, arid crys(mol. n t , tallizntion from dichlorobcnwne prior 906.5) to fluorination shoired no difference in yield of chlorofluoro 011.
c1 c1
18[ >,CF*]
+
LIQUID-PI14SE FLUORIAATIOY WITH AgFs
- 72.%F + 36HF
(2)
(mol. wt., 900) I n Equation 1 fluorine has not only added to the double bonds, but has replaced two thirds of the chlorine to give a complicated mixture of products containing 4 to 6 chlorine atoms. The yield by the first process is 45‘3 as compared v i t h 65% for the second “hydrocarbon” route based on organic starting material. However, it is advisable t o maintain a larger excess of AgF2 in the first process. Therefore the net weight increase in chloro-
Clilor.inated tcrphenyls were fluorinated with .IgI>z on a semiworks scale in a n oil-jacketed, 1 x 2 foot, horizontitl qtccl rcacbtor cquippcd iyith scraping agitation. This equipment \vas similar to that describcd on page 352 by Struve et al., x i t h the cxccyition that a screw feeder was employed to charge the solid chlorinatcd terphenyl. An inert fluorocarbon solvent was used to modcrate the reaction, as described by Struve. Fifteen pounds of chlorinated terphenyl (0.029 pound mole) wcre added at 150-160° C. over 5 hours to a slurry of 13 pounds of fluorocarbon solvent (boiling range 180-137” C. a t 10 mn.) and 125 pounds of AgFl (0.856 pound mole or 40.8 moles based on chloroterphenyl).
March 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
The reaction mixture was then heated to 230-240" C. for 10 hours and cooled, and the product \vas extracted v i t h triehlorotrifluorocthane. The washings were concentrated and distilled to r e c o w r the fluorocarbon solvent and obtain a product boiling at 140-230" C:. at 10 mm. pressure. The spcnt silver fluoridv, after rcpcnrrat ion to silvcr difluoJitlr, Tva': ready for another run.
OF FLr-oRIshTIosW I T H .IgF,: T.IUI.EI. RESLUTS
The yield of product \van 8.7 pounds (45.iYc of theory) and containcd 20'; chlorine. In addition, there was a distillation heel of 1 to 2 pounds roritaining 26w0 chlorine. 11-hen no inert fluorocarbon snlvent was used, many low boilers xere formed, and the yield of oil (boiling range 140-230" C. at 10 mm.) was cut by half. ll-hen ('oFd \vas used ill place of .\gFz o n a laboratory scale, a similar yiclld \\-a5obtaincd, but the product \vas niore difficult to isolatc hecaii.v of t h v voluminous cohalt fluoride residue.
CHIEFP R O D ~CC P OT X FLL-ORIPATIOX
CHLORINATED AROMATICSFROM:
-=-=-a p-Terphenyl
White wax' b.r. 140-230' C. a t 10 mm. ( x i e n C H C h crystallized, m.p. is 175' C.)
Triphenylene
L o a melting resin; h.p. a t 10 nmi.
> 140"
C.
1,3,5-Triphenylbenzene
o\p20O0 C. at 2
I
349
nim.
C H L O R I S h T E O .kROllATIC F R O I I :
R E.iTTiON
TRE.4TXEST
AND
AgFt
PRODCCT
1,3,5-Triphenylbenzene
0 fi
I
c
2,2'-DiphenyldiphenyI
Sbt's
l
L o w melting resin; b.p. a t 10 m m .
> 140'
C. Above chlorofluoro nil with
0
AgF2
Triphenylamine
4-Phenoxydiphenyl a - C ) - a - C r ) C o l o r l e a s
inin.
oil; h.p.
> 140'
Resin. b r . 170-220° C . a t 5 n ~ n i . ; 23.670 C1
C. a t 10
Dinaphthylene oxide
0
>145' C. a t 10
Oil; h . r . 140' C. (10 mm.)200' C. (2 rnrn.); 14.0% C1
= s . o Abol-e Phlorofluoro oil xyith
A+
ShF5
Oil; b r mm.
ApF2
Oil: b r . 145-185' C. (10 mm.): 11.5% C1
SbF5
: 2'40'
S-Phenylcarbazole Colorless oil: b.r. 140-230' nm.
C. at 10
A--A Oil. b.r. 140' C. (1D'mm.)C . (5 rnrn.);:?18.8%
c1
Dibenzanthrone
.4hore chlorofluoro oil w i t h
AgF2
Oil; b.r. > 140' C. (IO m m . ) ; 14.5% C1
ShFa
Oil; b.r. 145-200O C. (10 mm.); 15.0% C1
Triphenylene
0'
0
350
INDUSTRIAL AND ENGINEERING CHEMISTRY
When the product was treated with 14 moles of AgF2 a t 200" C. i n a steel pot, the result was a colorless oil with a boiling range of 145-190" C. (10 mm.) that contained 15.5y0 chlorine. The over-all yield was 60% of theory from chloroterphenyl assuming the final product \vas C1,F2&lr. The chlorofluorocarbons prepared from chlorinated 0- and mterphenyl with AgFl were colorless oils boiling from 140" to 230" C. (10 mm.). A mixture of the two terphenyls gave a chlorofluoro oil with a viscosity about 5 centipoises lower than either component alone a t 210' F. A n analysis of such a mixed product indicated ClsHo.lCl6F2a.3 as a n average formula. The chlorofluoro oil had a viscosity of 20-25 centipoises a t 210" F.; a t room temperature it mas a clear, sticky mass. The density a t 210" F. was 1.8 compared t o 1.85 for fluorocarbon oil prepared by the AgF2 liquid-phase process. T h e viscosity index 1100; the viscosity change with temperaturr, thereforc, was was greater than t h a t of fluorocarbon material which had a viscosity index of -700. Chlorofluoro oil was thermally unstable in glass above 250 ' C. a n d slowly gave off acid fumes; thermally it was not so stable a s fluorocarbons which withstand heating a t 300" C. in glass. Furthermore, the chemical stability to AgF2 was not so high as t h a t of the fluorinated material, in that, upon retreatment, with .AgFp a t 220-240' C., i t gradually broke down into lower boiling products. Exposure to 2070 fluorine (diluted with nitrogen) caused explosive decomposition a t 240" C. Vapor-phase per-
-
Vol. 39, No. 3
fluoro oil did not react with dilute fluorine a t 300" C. The chloro compounds shown in Table I were fluorinated with A4gF2. K i t h the exception of chlorinated p-terphenyl, the yields of chlorofluorocarbons in the desired boiling range mere poorer than with o- or nz-terphenyl. It appears noteworthy that the oxygen linkage in Chlorinated 4phenoxydiphenyl survived, inasmuch as the oil boiled above 140' C. (10 mni.), as do terphcnyl oili. The chlorinated aromatic compounds listed in Table I1 mere reacted with SbF, and then treated with AgF,. They were less interesting than the terphenyls in fulfilling the objective of preparing a chlorofluoro oil, both in respect to yield and properties. The reaction with SbFs (15-20 moles) was effected in an aluminum bomb a t 200-225' C . The aftertreatment with AgF2 (515 mcles) was carried out in a small steel pot a t 150-200 ' C. The nitrogen bond was apparently intact in both triphenylamine and S-phenylcarbazole reaction products, as indicated by the boiling range of the chlorofluoro oils. However, the oxygen bond in chlorinated 4-phenoxydiphenyl, which survived the AgFg reaction, n x s split by SbFj as indicated by low boiling reaction products. P R E S E S ~ Lbefore D the Symposium o n Fluorine Chemistry as paper 88, Division of Industrial and Engineering Chemistry, 110th Meeting of the AMERICANCHEXICAL SOCIETY,Chicago, Ill. T h e work described in thin paper is covered also in a comprehensive report of work with Buorine and fluorinated compounds undertaken in connection with the hianhattan Project. This report is soon t o be published as Volume I of Division V I 1 of the M a n h a t t a n Project Technical Series.
(PREPARATION OF CHLOROFLUOROCARBOY S)
Fluorination o f petroleum oils in vapor phase with cobalt trifluoride C. F. Irwin, R. G. Benner, A. F. Benning, F. B. Downing, H. XI. Parrnelee, and W. V. W-irth E. I. D U P O N T D E N E M O U R S
& COMPANY, IUC., WILMINGTON, DEL.
A METHOD is described for the preparation of perfluorocarbons having a boiling range of 180" to 350" C. at 760 mm. niercury by the fluorination of hydrocarbon oils in the vapor phase over cobalt trifluoride. The equipment used, variables affecting the yields, methods of finishing the fluorination, and some physical properties of the perfluorocarbons are discussed.
provisions were made t o ensure vaporization of the feed stock and reaction products in the reactor and auxiliary equipment. This was accomplished by employing an electrically heated preheater (n) for heating the inert gas used to assist in vaporizing the feed stock, an electrically heated vaporizer and manifold ( b ) , and an elcctrically heated screen stack and take-off line (c), in place of the 0.5-hch coil condenser used in diperfluoromethylbenzene work were two condensers ( d ~i n series, one cooled with water a t H E vapor-phase fluorination of hydrocarbons with cobalt 30-40" C. t o condense high boiling perfluorocarbons, and the trifluoride (1) was extended t o the higher boiling oils, such as second cooled with carbon-ice-trichloroethylene t o condense kerosene and light lubricating oils, in order to obtain pcrfluorohydrogen fluoride and low boiling perfluorocnrbons resulting from cracking. These conclcnsers had a wide bore to prevent carbons with a boiling range of 180" t o 350" C. a t 760 mm. plugging by the very viscous products. *L calcium chlorideAmong the uses for such perfluorocarbons is that of a reaction medium for some fluorination reactions. manometer attachment was u w l t o check the prcwure in the The react,ions involved in the preparation of perfluorocarbons reactor. by this method may be written as follows: The reactor was loadcd with 83 pounds of CoF2 irhich, after conversion to CoFp, was theoretically sufficient to produce 11 200-300 a C.+ 2CoFI (l) pounds of perfluorocarbon from 3 pounds of hydrocarbon i n a 2CoF2 Fn single cycle. This amount of C o F 2 left ahout 1.3 cubic feet of free space in the reactor or about half of the total 4nCoFa -(CHn)n275-350" "+ -(CFn).4nCoFn 2nHF (2) volume. The procedure used in fluorinstion follows: The tcamperature At the temperatures used, the replacement of hydrogen by fluoof the oil vaporizer wvne adjusted to 350" C., the reactor t o 300°, rine was fairly complete, but the yields were seldom above 80% and the icrwn-stack and takc-off line to 380". The floLv of inert because of cracking or thermal decomposition. gas (hydrogen fluoride or nitrogen) wvns adjusted to 8 reactor EQUIPMENT AND PROCEDURE volumcs (free space) per hour, and the flow of feed stock WVBB started into the vaporizer. The rate of feed varied, as will be T h e equipment (Figure 1) was essentially the mme a8 that discussed later, from about 22 to 51 reactor volumes per hour, ueed i n the fluorination of hexafluoroxylene (8) except that
T
+
+
+
+
