March 1947
INDUSTRIAL AND ENGINEERING CHEMISTRY
The steam distillate was dried with calcium siiifnte and rectified t o yield 20 grams of l-(pentafluoroethyl)-4-(trifluoromethyl)benaene, 505 grams of l-(chlorotetrafluoroethyl)-4-(trifluoromethyl)benzene, 350 grams of chloro-l-(chlorotetrafluoroethyl)-4-(trifluoromet,hyl)benzene, and 147 grams of dichloro-1-(chlorotetrafluoroethy1)-4-(triflnoromethy1)benzene; this represented a yield and conversion of 8 5 5 . Concurrent, chlorination and fluorination were obtained by adding chlorine t o tlie reaction mixture during fluorination. I n this process l-(pentachloroethyI)-4-(trichloromethyl)benzene (1482 prams, 3.75 moles) and 1482 grams (5.0 moles) of antimony pentachloride n-ere plnced i n t h e reactor. Ti\-elve hundred grams (GO.0 moles) of anhydrous hydrogen fluoride !yere added as in the preceding example. .ifter addition, 426 grams (6.0 moles) of chlorine were b~ibbletlinto the mixture over a period of 0.5 hour, the temreraturr riiing to 120 C. Hydrogen fluoride (382 grnnis, 19.1 molw) n.:iq pnsseti into the 1,eaction mixture during 1 hour: t l ~ ere:iction mixture ~ n then s hented :it 230' C . for 3 hours. During this period p u t of the product di+llcc! into t!ie receivei~;.
399
The crude fluorinated product was treated as ahove, 1191 grams being obtained. Rect,ification of the product yielded 221 granis of 1- (chlorotetrafluoroethyl)- 4 - (trifliioromethyl)beiizene, 283 grams of chloro-l-(chlorotetrafluoroetti~-l)--l-(trifl~iorometliyl)benzene, 385 grams of dichloro-l-(chlorotetr:ifluoroethyl)--l-(trifluoromethyl)benzene, 181grams of trich1ot.o-1-(chlorotetrafluoroethyl)-1-(trifluoromethyl)benxene, and 52 grams of tetrachloro-l(chloroteti~afluoroet~liyl)-1-(trifliioromethyl)heii~e~ie. The yield and conversion xwre 855;. T h e compounds were purified by rectificntion in n 1'odbielni:ik Hyper-Cnl column. ACKKOWLEDGRIENT
The nuthors 11-ish t o aclction-ledge tlie financinl United States .limy -lir Forcer IInt6riel Center :inti Ethyl Corporation and grntefully ncknonlcdge the :in:ilytic:il n-orli oi .I.11. Riblev. f r o m a doctoral thesis of 0 . R . Pierce, f a c u l t y oi I'urdue Yni\-er:ity.
.~BSTR.ACTED
10
be submitted t o the
[ (PERHA LOA LKY L)B EN Z EN E SI
FUuorinated deriuatives of p-isoprop yCtoUuene and isoprop yUbenzene E. T. McBee and 0. R . Pierce ISOPROPY BENZENE and p-iscpropyltoluene were chlorinated photochemically in the liquid phase to produce the corresponding (heptachloroisopropj 1)benzene and 1-(heptarhloroisopropj 1)-4-(trichloromethyI)benzene. These chlorinated hydrocarbons were fluorinated with anhj drous hydrogen fluoride or antimony trifluoride under autogenous pressure and with hydrogen fluoride at atmospheric pressure. Optimum yields of fluorinated product were obtained with the latter procedure. Physical constants and halogen analyses are reported.
AS?
< T. \ L V r . i T I O S of the properties of fluorinated branchedch i i n nlkylbenzenes was desired, especially as compared t o those of the straight chain analogs. For this reason fluorinated derivatives of p-isopropyltoluene and isopropylhenzene were prepared. The chlorinated intermediates, l-(heptachloroisopropyl)-4(trichloromethy1)benzeiie and (heptachloroisopropyl)benzene, were obtained by photochemical chlorination of the correspond-ing hydrocarhon :it temperatures ranging from 150" to 200" C. These compounds n-ere fluorinated according t o several different procedures: ( a ) with mixed trivalent and pentavalent antimony halides, and ( h ) with anhydrous hydrogen fluoride and pentavalent antimony clilorofluorides. The latter prepared from equal weights of anhydrous hydrogen fluoride and antimony pentachloride were found to give best yields and conversions a t atmospheric pressure fluorinations. I-lrocedure b was also productive of fluorinated derivatives containing chlorine atoms substituted in the ring. I n assigning positions t o halogen atoms, i t was assumed t.hat chlorine atoms in allylic positions were readily replaced b y fluorine. The remaining chlorine atoms were substit.ut,ed by fluorine with more difficulty, requiring reaction temperatures of 300 O to 3.50' C. in some instances.
The l-ihept:ichloroisopropyl)--l-(tricl~loronietli~l) tierizenr iiwd as starting mnterial for fluorinations melted :it 128" =t 0.3" C. High purity n-as important for good yields and conrerbions: quantities of unidentifiable tars were produced from fluorintitioii of impure Famples. -1s (hei)tnchloroisoproI,!-l)henzeue could not be isolated in a pure state, yields and cotiv(:rsioiis on fliiori1i:ition v e r e relatively low. Large samples of I-(heptafluoroiqopropyl)-4-(trifluoromethyl)benzene, (heptafluoroisopropy1)benzene, and (chlorohesafluoroisopropy1)benzene were preptired from partially fluorinated derivatives of l-(lieptachloroisoI)ro~)yl)4-(trichloromethy1)benzene and (hept,achloroisopropyl)benzene, since these compounds undergo less decomposition. X mixture of antimony trifluoride and antimony pentachloride as Huoriiiatirig agent was more suitable for the prep;iration of these compounds than anhydrous hydrogen fluoride, since lover reaction pressures were required. The apparatus and techniques are descrihed in the third paper of this series (page 397). CHLORINATION
(Heptachloroisopropyl)-4-(trichloromct~iyl)bc~i~cncwas prcpared b y placing 600 grams (4.17 moles) of p-cymene (boiling range, 175-177' C.) in the chlorination apparatus and bubbling chlorine into i t at the rate of 2.5 moles per hour. After. :in induction period of about 5 minutes the reaction occurred rapidly. The reaction temperature was adjusted as follows: 20" for 8 hours, 100" for 15 hours, 150" for 8 hours, and 175" C. for 5 hours. S e a r the end of this period i t was observed t h a t a liquid, later identified as carbon tetrachloride formed by chlorinolpis, was refluxing. Chlorine introduction \Tas discontinued, and excess chlorine and hydrogen chloride were removed by aeration a t 100' C. The products were poured while hot into 500 ml. of equnl volumes of benzene and methanol. Upon cooling a solid separated and was removed by filtrstion. Repeated crystal1iz:itions from a benzene-methanol mixture yielded 1290 grams (2.7
Vol. 39, No. 3
INDUSTRIAL AND ENGINEERING CHEMISTRY
400 TABLEI.
-
P H Y S I C A L C O S S T h S I'S AS11 H h L O G E S .%S.iI.YSES OF L-EV- ( ' 0 M P O ~ S I ) S DERIVED FROJI 1)-cY\lESE A S D C V h I E S c
__
Coinpound
I\lm
130 0-130 3 161.3-161 6 190.0-190.3 219.0-219.3 240 0-240 3 236.1-236.4 258.9-259.2
748 i48 i51 731 id8
,,
20"
Mol. TTt Theoretical F o u l l d
d:6
748 748
1,3861 1 4093 1 4292 1 4609 1.4928 1 4780 1,4972
1.4127 1,4846 1.5243 1 5617 1, 6163 1.5996 1,6180
127.3-127 6 157,l-137 4
74s id8
1'4112 1 4403
1' 48i5 1,5477
186.0-186 3 21.5 0-215 3 238.2-238.5 260.3--260.6 282 5 - 2 8 2 . 8
748
1 47,30 1 -1884 1.5140 1.3340 1 5625
1 6264 1 5427
......
748 748
748 i4b
1,5930 1,6592 1,6993
moles) of a n-hite crystalline solid, l-(lieptachloroisopro~)yl~-4(trichloromethy1)benzene (melting point, 128.0' C.). Conversion and yield were 60 and 90%, respectivcly. A low reaction temperature during initial stages of ch1oriii:ition was necessary t o prevent tar formation by thrrnial tleligdrochlorination of intermediate, partially ehlorinatctl compounfiand subsequent impedance of the react,ion. I n the chlorination of isopropylbenzene 480 grams (4.0 moleof cunii'ne (boiling range, 156-157" C.) n-ere placed in the chlorination apparatus, and chlorine \Fas introduced a t a rate of 2 moles per hour. .liter a short, induction pcrioti thc! reart,io:i began and the temperature rose rapidly. -1temperature of 20' C'. was maintained by circulation of i w t e r through tlie cooling coil. The reaction temperature was held a t 20" for 12 hour., 100" for 16 hours, 150' for 12 hours, and a t 17.5' C. for 8 houw. \ T ' l i ( * ~ i the reaction m i s complete, the contents of the tribe \vycr(' ac$r:itc,ci to remove gases. T h e chlorinated mixture ivas analyzed an11 found t o contain 69.5% chlorine, a slightly higher value than tli,. theoretical (68.7%) chlorine content of (heptacliloroisopr(jp~-lbenzene. Attempts made to crystallize a product from tlie reaction misture were unsuccessful. ;itt,empted rectification a t Ion. pressure. resulted in extensive decomposition. The chlorinated mixtuw was found t o be useful material for fluorination. FLUORINATIOS
Anhydrous hydrogen fluoride and antimony pentachloride at atmospheric pressure were used successfully. S i n e hundred fifty-eight grams (2.0 moles) of l-(heptachloroisopropyl)-4-(trichloromethy1)benzene and 958 grams (3.42 moles) of antimony pentachloride were placed in the nickel reaction vessel and heated to 100" C. Anhydrous hydrogen fluoride (958 grams, 47.9 mole. I was bubbled into the mixture with stirring throughout the rcbaction period. T h e rate of hydrogen fluoride flow was 300 grams per hour. -4fter all t,he hydrogen fluoride was added, tho reaction mixture was heated a t 220" C. for 3 hours. The product was removed from the react,ion vessel and thc traps, x~ashedw i t h dilute hydrochloric acid and aqueous sodium hydroxide, ani1 steam-distilled. Six hundred fort#y-sixgrams of crude fluoriilateil product were obtained, dried, and rectified. Rectification gave 104 grams of l-(dichloropentafluoroisopropyl~-4-(trifluoron~e thyljbenzene, 218 grams of l-(trichlorotetraRuoroisopropyl~-4-(trifluoromethyljbenzene, 199 grams of 1-(tetrachlorotrifluoroisopropy1)-4-(trifluoromethyl) benzene, and 83 grams of chloro-l(trichlorotetrafluoroi~opropyl)-4-(trifluoromethyl)henzene. Yield and conversion were 867,. One thousand four hundred forty-two grams of impure (heptachloroisopropyljbenzene and 1442 grams (4.8 moles) of antimony pentachloride were placed in the nickel reaction vessel and heated to 90" C. Fifteen hundred grams (75.0 molrs) of
314 830.5 347 363.5 380
398 432.5 479 246 262.5 279 295 5 312 346.5 381
"0 Cl Theoretical
q F round
Theoretical
E'ound
841 25.7 18.3 16.4 14.9
:33.9 25.6 18.6 16.9 14.6
311 328 344 359 373 394 427
244 261
13 6
13.7
277 293
25.5 86.1
25.3 36.3 45 5 51.2 56.2
211' - ._
341 377
+i 01.2 56.0
:t~ihydroushydrogen Huoride were bubbled into the stirred re: d o n mixture at the rate of 300 grams per hour. .Ifter all hyt1ro:en fluoride wa3 added, the reaction mixture was heated a t 220" C. for 2 hours. Tlio reactor was cooled to room tempcr2Lture n ~ Gd O grsms of liquid product were obtained, together with a qu:intity uf unidentifisblc tarry miterial. Tlie product \vas n - u h c d with dilute. hydrochloric acid, steam-distillcd, dried, anti rectified. Four distinct fractions were obtained: 56 grams of ( i ~ i c l i I o r o p e n t a A u o r o i ~ o ~ ~I benzene, r o ~ ~ y 1 250 gram3 of (trichlorotetrafuoroisopropylj benzene, 136 gramr of (tetrnclilrjrotritluoroisopl.opT-lii)eiizeiic, and 140 grains of cliloro-(tetrachlorotrifiuoroi ~ o p r ~ ~ p ~ l l l , c ~ f iTlie ~ e nyield e . and conversion were 5Sqo,. .\c~~~rdin:: to the procedure described in the third piper of 1 his ?dricz,s ( p i g c 397 1, n i o r ~highly ring-chlorinatcd fluovo tlerivativcs R X ~ I ~o ~ h' ~ ~ ~ Iiy i n the d iiitroduction of chlorine into the reaction niisiurc duriiig fluorimition. Anhydrous hydrogen Huoride and antimony pentachloride at superatmospheric pressure were then inawtigated in order t o o b t i n more highly fluorinated produ
1. Four hundred seventy-nine grams (1.0 mole) of 1-(heptacliloroisopropyl)-4-(trichloromethyl)benzene and 50 grams (0.17 mole) of antimony pentachloride were placed in the autoclave, and 100 grams (20.0 moles) of anhydrous hydrogen fluoride
distilled into the reactor from a small steel container. .I tcmperature of 175" C. mas maintained for 30 hours with constant agitation of the reaction mixture. T h e pressure in the reactor ro.?e t o 3000 pounds per square inch during the reaction. The autoclave was then cooled t o room temperature, gases were bled off into aqueous sodium hydroxide, and the liquid product was treated as described previously. Rectification produced four fractions: 10 grams of l-(heptafluoroisopropyl)-4-(trifluoromet>hyl)benzene, 50 grams of 1-(chlorohexafluoroisopropyl)-4(trifluoromethyl)benzene, 88 grams of 1-(dichloropentafluoroisopropyl)-4-(trifluoromethyl)benzene, and 48 grams of 1-(trichlorotetrafluoroisopropyl)-4-(trifluoromethyl~bcnzene. 2. Three hundred sixty grams of crude (heptachloroisopropyl) henzene and 90 grams (0.3 mole) of antimony pentachloride were placed in the autoclave. Two hundred grams (10.0 moles) of anhydrous hydrogen fluoride were introduced, and the autoclave was heated at 150" C. for 24 hours with constant agitation, the pressure rising to 2500 pounds per square inch. One hundred. grams of crude fluorination product mere obtained, treated as described, and rectified t o produce two fractlons: 44 grams of (trichlorotctrafluoroisopropyl) benzene and 34 grams of (tetrachlorotrifluoroisopropg1)benzene. Yield and conversion were 2,jC*,,assuming t,hestarting material to be (heptachloroisopropy1)Ixnzene. -1ntimony trifluoride and antimony pentachloride at superatmospheric pressure have been used frequently t o obtain halogen exchange. Hence this process was applied t o these compounds having branched chains: 1. .l mixture consisting of 173 grams (0.5 mole) of l-(dicliloropentafluoroisopropyl)-4-(trifluoromethyl)benzene, 181 grams (0.5 mole) of l-(trichlorotetrafluoroisopropyl)-4-(trifluoromcthylbenzene, 500 grams (2.8 moles) of powdered antimony trifluoride
INDUSTRIAL AND ENGINEERING CHEMISTRY
March 1947
'
40 1
decanted. The fluorinated product was trclated as described, 219 and 80 grams (0.27 mole) of antimony pentachloride iwre placed grams of product being ohtaincd. Rectifica in the autoclave: the niisturc n-as heated a t 340' C. for 48 hours fractions: 49 grama of (hrptafluoroisoprop?.1) with constant agitation. T h e autoclave x-asthen cooled to room afluoroisopropyl I txxzene, and 36 temperature, and liquid products w r e decanted from solid anopropy1)bcmene. Conversion t timony salts remaining in the reaction vessel. The fluorinated material n-as ivahhed ivith dilute hydrochloric acid and steamne \vas 1 0 5 and t o (chlorohe diqtilled. TKOhundred grams of crude product vere obtained, benzene 15yc. The yield Tvas 3 5 s . dried, and rectified. Three separate fractions were obtained and T h e compounds ivcrc purified by rcctificntion in a Podbic.lili;ili identified as 43 grams of l-(heptafluoroisopropj-l!-4-(trifluoromethyl)benzene, 83 grams of l-(chlo~olieuaflnoroisoprop~l~i-4- Hyper-Cal column. The physical consrsnt-: and halogen a 1 1 ~ 1 y (trifluoroniethvl)benzene, and 35 grams of 1-(dichloropentases are given in Table I. fluoroisopropvl~-i-(trifluoromethyl)benzen~,Conversion to 1ACKSOWLEDG3IEKT (heptafluoroisopropyl)-&(trifluoromethyl)benzene was 1 3 7 ~and the yield 30c';. The authors \vis11 to ac.l;no\vlcdye the financial assiut:iiii,i, oi rent,y-four granis of a mixture composed of (dichloropentafluoroisopropyl)benzene, tlie United States Ariiiy Air Forces IIstkricl Ccnter and 1,2thyI of (trichlorotetrafluoroisoprop?-l~~enzene, Corporation and grati.fully acknon-lcdgc the annlyticnl \ v ( i i ~ k[ i f 400 gram. ( 2 . 2 moles) of powdered antimony trifluoride, and 90 -4, 11.Ribley in coiincction with thi5 paper. grams (0.3 mole) of antimony pcntachloride 71-ere placed in the ABSTRACTEDf r o m a doctoral theeis of 0 . R . Pierce, tu he s u b m i t t r d t o t h e autoclavc. The reaction was heated at 330' C. for 30 hours and faculty of Purdue University. then cooled to room trmpcrature, and the liquid products w r e
FLUORINATION OF PERHALOGEN OLEFINS R illiaiii T. JIiller. Jr.. Robert L. Ehrenfeld, James 31. Phelan', \\Taurice Prober2,and Sherman IC. Reed3 CORY1 L L L \ I \ E R S I T T
% \ D I H E S . t . \ I . L i B O R 4 T O R I F S O F THE M4\iH4TT421 PROJECT, I T H i C i ,
ELE\lEYT iR1 fluorine was applied for the fluorination of perfluoro- and chloroperfluoro-olefin3 in s y lithesizing saturated fluorocarbons. Direct fluorination of liquid mono-olefins at lo\+ temperatures y ieldecl principally simple fluorine addition and dimer addition products. P, ith a n olefin rontainiug more than one double hond the dimerization reaction could continue paat one stage to yield a series of poljiner products. Loalr temperatures faalored the dimerization reaction, whereas at higher temperatures and i n Lhe vapor phase polymer products could be largely a i oided and simple saturation carried o u t as a continuous process. Cobalt trifluoride w a s shown to be an effectiale fluorinating agent for perfluoro-olefins. This reagent, which represented an indirect use of elementary fluorine, added fluorine to double bonds to yield saturated products w ithout the dimerization reaction characteristic of free fluorine.
E
7 LEMEXT-4Rl- fluorine was utilized as a fluorinating agent for perhalogen olefins by direct reaction and for the preparation of reactive metal fluorides. The principal products obtained iron1 the reaction of a completely halogenated liquid olefin n-ith fluorine are the normal addition product .4 and the dimer addition product B ( 2 , 7 ) .
-C=C-
+ F2 --+ -C-C
f -C-C-C-C-
I
I
F F d
I F I3
F
Varying amounts of by-products from the replacement of chlorine by fluorine, in t h e case of chlorofluoro-olefins, were usually formed. The replaced chlorine was accounted for as chlorine and chlorine fluoride addition products of the starting olefin and, to a lesser extent, by dimers corresponding t o the addition of chlorine or of chlorine fluoride. The dimerization reaction was of especial interest in t h a t i t represented a distinct type of reaction for fluoPresent address, Standard Oil Derelopment Company, B a y w a y . S . J. Present address, General Electric Company, Schenectady, S . Y . a Present address, Bucknell University, Lewisburg, Pa. 1 2
\.
I . . 41D \ F K I O R K .
\.
I.
rine among the halogens and provided a uxeful synthetic method leading to the forination of higher niolecwlar xeight compounds from low molecular weight olefins. FLUORIS.4TIOS I S THE LIQPlI) PHASE
Liquid-phase fluorinations n-ere carried out in apparatus (Figure 1) usually constructed from copper or nickel tubing and in various sizes. The general method was essentially that previously descrihed ( 7 ) . Fluorination occurred rapidly nith the simple perhaloqeii olefins, and a sharp change in fluorine absorption indicated the practical completion of reaction. Solvents such a i 1,1,2-trichlorotrifluoroetlianeor trichlorofluoromethane andlor nitrogen dilution of the fluorine were employed t o moderate reaction conditions and/or t o reduce the viscosities of liquids nt loiv temperatures in some cases. Most of the fluorine used in this work was produced by :Lsmall cylindrical nickel electrolysis cell of a design in use a t Cornel1 for some time (Figure 2). This was operated Tvvitli an electrolyte containing up t o about 1.8 moles of hydrogen fluoride per mole of potassium fluoride ( 5 ) n-ith a current efficiency of about goyG. The rate and quantity of fluorine production were determined by measuring the hydrogen output. The size of cell show1 x a r operated satisfactorily xvith an electrolysis current up to 25 amperes. The purity of fluorine produced and the smoothness of cell operation Ivere found to be essentially dependent upon maintenance of a n absolutely dry electrolyte. A special redistilled grade of anhydrous hydrogen fluoride (supplied by F. B. D o m i n g of the D u Pont Company) was w e d for charging. Fluorine compressed into tanks \vas utilized after a satisfactory technique for bottling n-as worked out (9). The temperature of fluorination had an important be;triiig upoil the t y p e of fluorination products obtained. I m v temperatures favored the formation of fluorine dimer addition products relative to the normal addition product and minimized tlie forination byproducts. Higher temperatures resulted i n proportionally higher yields of normal addition products and of ti)--products associated with the replacement of chlorine in the case of chlorofluoro-olefins. Table I lists yields of purified fractions of typical products which were isolated from the reaction of sym-dichlorodifluoro-
