(PERHALOALKY UBENZENES Fluorinated derivatives of inesit ylene E. T. McBee and R. E. Leech' PURDUE USIVERSITY 4 N D PURDUE RESEARCH FOCSD.ATION, LAFAYETTE, IND.
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TABILITY and non3IESITYLENE was chlorinated photochemically to prochloride were removed by f l a m m a b i l i t y , which duce 1,3,5-tris(trichloromethyl)benzene. Optimum yields aeration, and the product characterize many organic were obtained by conducting the reaction in carbon tetra\vas further purified by dischloride solution. Various ring-chlorinated derivatives of tillation and crystallization. polyfluoro compounds, are 1,3,5-tris(trichloromethyl)benzene were prepared by ring Two separate procedures properties desirable in heat chlorination of mesitylene in the presence of iron turnings were used in the phototransfer agents and hydraulic fluids. Certain fluorinated and subsequent photochemical chlorination of the side chemical chlorination of d e r i v a t i v e s of a r o m a t i c chains. The chlorinated mesitylenes w-ere fluorinated mesitylene. These were with anhydrous hydrogen fluoride or antimony trifluoride chlorination in carbon tetrahydrocarbons are quite stable, and an evaluation of under autogenous pressures. Optimum conditions are chloride solution and chlorination in the abPence of ii other aromatic polyfluorides reported. solvent. In the first, p ~ ' o c r :is he:it transfer fluids and dure 60 grams (0.50 mole) of mesitylene and 500 nil. of cnrbon hydraulic fluids was desired. For this reason 1,3,5-tris(tritetrachloride Jvere mixed in the chlorination apparatus arid fluoromethy1)benzene and its ring-halogenated derivatives were heated to 80" C. Chlorine \vas t.hen bubbled into the soliiprepared and their properties studied. tion continuously for 48 hours. Solid product was recrysThe synthesis of 1,3,5-tris(trichloromethyl)benzene by phototallized from benzene, and 210 grams of 1,3,5-tris(trichloroclieniicirl chlorination of mesitylene a t 150-175' C. i. desrribed methy1)benzene (melting point, 88.0-88.5' C.) rrere oht:iined. in the p i t e n t literature (3). I n this laboratory i t \vas found that This represents x yield of 0 8 5 . higher yields of 1,3,5-tris(trichloromethy!)benzeiie were obtained I n the second procedure 240 grams (2.0 moles) of niesitylene I)>- chlorinntion of mesitylene at, 80' C.in carbon tetrncliloride n-ere chlorinated in the absence of a solvent a t 150" to 175" C. than by chlorination a t 150-175' C. iii the absence of a solvent, .\fter 336 hours of chlorination, carbon tetrachloride \viis obas conciderable chlorinolysia occurred :it the higher temperatures. served t o be refiusing. The flow of chlorine vas stopped and tile Chloro-bis(trichloromethy1)benzene \vas identified as one of the reaction mixture distilled under reduced pressure. Five hunchlorinolysis products. dred eighteen grams of product, boiling in the range 149' to The ring-chlorinated derivatives of mesitylene xvere prepared 150 'C.a t 1 nim. mercury pressure, rvere obtained and ident,ified :is by chloriuation of the hydrocarbon in the presence of ferric 1,3,E1-tris(trichlorometh~-l)benzene.The yield n-as 60.2('~. A chloride. Tlieae compounds were then chlorinated photochemisniall quantity of chloro-bis(trichloroniethy1)benzene w:is aI..o cally. usually in carbon tetrachloride solution, to form the correobtained from the reaction. 1Zeaction times of ahortw c1iir:itiun sponding chloro-tris(trich1oromethyl)benzenes. 2-Fluoro-1,3,5gave still smaller yields of the desired product. trimethylbenzene was also chlorinated photochemically in carbon The three possible ring-chlorinated derivatives of rhesitylene tetrachloride and gave an excellent yield of 2-fluoro-1,3.5-triswere prepared from the chlorination of mesitylene by the Co1lo~(trich1oroniethyl)benzeue. ing procedures: The various chlorinated mesitylenes were fluorinated x i t h anhydrous hydrogen fluoride or with antimony trifluoride in the 2-CHLoRo-1,3,5-TRIUETH~LBESZESE, S i I l , hUntbCd SCVentypresence of antimony pentachloride under autogenous pressure. two granis (8.09 moles) of mesitylene \rere poured into a thrceComplete replacement of chlorine by fluorine in the trichloroneck fladk innnersed in a n ice bath. Light w a . ~excludcd by a methyl groups w n s obtained. In no instance was there any cover fitt,ed over the top of the ice bath and around the n e c k s of evidence that ring chlorine atonis had been replaced by fluorine. the flask. One gram of dcgreased iron'turnings \vas added to the mesitylene and the mixture cooled to ice temperature. Six This reaction is t o be espected, since the chlorine atoms in the hundred thirteen grams (8.65 moles) of chlorine were hubbled into methyl group are in allylic positions to the aromatic nucleus, the mixture a t a rate such that the reaction temperature did not whereas the ring chlorine atoms are in a vinyl type position. rise above 10' c'. Rectification of products gave 798 grams (5.90 Physical constants of t,he nevi compounds are summarized in moles) of 2-chloro-1,3,5-trimethylbenzene(boiling point a t 1.5 mm., 51-52" C.). This represented a 73.lYc yield. Table I. 2,4-DICHLoRO-1,3,5-TRI.\IETHYLBEXZESE.One hundrcd fiftyfour grams (1.0 mole) of 2-chloro-1,3,5-trimethylbenzene were CHLORINATIOX S mixed lvith 150 nil. of carbon tetrachloride. One gram of degreased iron turnings was added and the reaction mixture cooled Chlorinations were conducted in a round-bottom three-neck t o 0-5' C. Chlorine (101 grams, 1.41 moles) \vas then bubbled flask fitted with a thermometer well, reflux condenser, and chlorine into the mixture at a rate such that the temperature remained inlet tube. The size of the flask was determined by the quantity below 10" C. Rectification of the product gave 117 grams (0.62 mole) of 2,4-dichloro-1,3,5-trimethylbenzene (boiling point a t of starting material. Light for the photochemical reaction was 4 mm., 92-94" C.), a yield of 62%. supplied by three 150-watt incandescent lamps located in prox2,4,6-TRICHLORO-1,3,5-TRIYETHYLBENZEXE. One hundred fiftyimity to the flask. Sufficient heat to maint,ain the reaction misfour grams (1.0 mole) of 2-chloro-1,3,5-trimethylbenzenewere ture a t the desired t,empecature was also supplied from the lamps. chlorinated in a manner similar to that described for the preparati on of 2,4-dichloro- 1,3,5-trimethylbenzene ; 169 grams (0.76 On completion of the experiment dissolved chlorine and hydrogen mole) of 2,4,6-trichloro-1,3,5-trimethylbeneene (melting point, 204-205" C.) were obtained. This melting point is in agreement 1 Present address, Carbide and Carbon Chemicals Corporation, South by Fittig ( 2 ) . with that reported Charleston, W . Va. The yield was 7 5 . 8 5 .
393
INDUSTRIAL AND ENGINEERING CHEMISTRY
394
Compound
O
c.
B.1'.
TABLE I. PHY>ICAL PROPERTIES OF F L ~ O R I N A DERIVATIT-ES TED OF S I E ~ I T T L E S E 7 c1 him,
166.6 119.6 126.4 152.4 71 1 130-131 149-150
..... ..... ... .
b
Vol. 39, No. 3
744 750 753 750 5 4 1
.. .. ..
N.P., c. -36 7 9 0 -10 2 - 3 0 61 n 93--94 88 0-88 5 170-lil
d:" 0 Si45 1.5139 1 5933 1 6316
142-144
178-179
,, y
1,4809 1.3558 1.3555 1,3903
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.
.... ,...
..
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lf,ll.~ia
40 343 40.695 41,103 46.m i
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A.R.I. b 1 15i 1,101 1 137 1.144 ..,
... . . ,
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Calcd. 0.0 0.0 0.0 11.2 20.2 27.8 (4.2 76 3 78 2 79.8
Found 0.0 0.0 0 0 11.2 20.5 28.2 i4 1 76 0 7s 0 79.7
z-I' Calcd.
Found
60.7 63.4 54 0 48.7 44 5 ..
60'6 63 3 53.9 48.1 44.7
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M o l a r refractirity a t 25' C. ;itomic refractivity a t 25' C.
2 - C ~ I L O R o - , 2 , 4 - D I C I I L O R O - , 2 , 4 , 6 - T R I C H L ~ R O - l , 3 , ~ - T (TRICHLORI~ ROMETHTL)BEXLESES. These compounds n-ere prcpared by
;1-t~~i~(ti~ifluori1metli~l)l~e:i~ene. Rextioii temperatures \\'we in tlie m i g e 220--280 C. The conversion to 2-chloro-1,3,5-trisphotochemical chlorination of 2-chloro-, 2,4-dichloro-, and 2,4,6~t~ifliioromethyl)herizene (boiling point at 750 mni., 133-153 ' C.) trichloro-1,3,5-trimethylbenzenes in a manner similar to t h r first \VAS j8.5c; : to 2,~-tlichloro-l,3,~-trii(trifliiorometliyl)berlzene procedure described for the preparation oi 1,3,5-tris(trichloromethy1')benzene from mesitylene. The conversion to P-chloro(melting point, 60-61 C.) 2S.Zc; : and t o 2,4,G-trichluro-1,3,51,3,5-tris(trichloromethyl)benzene(melting point, 170-171' C:.) was %ye, t o 2,1-dichloro-l,3,~-tris1~trichloronieth~-l)beiizcnit trij(trifluoromet1i;vl)beiizeiie (melting point, 93-95' C.) IOc;. In the synthesis of 2-fluoro-l,3,5-tri~(tricl~lor~~metli~-l)he1r~ene, (melting point, 142-134" C.) S7T0, and t o 2,1,6-trichloro-1,3,569.1 gr:rms (0.5 mole) of 2-fluoro-l,3,5-trinieth3lbe11zellr, prctris(trichloronicthy1)benzene (melting point, 178-179' C.) 3 7 . 2 5 . I n r e d b y the deconipobition of the diazonium horofluoride of 2-umiiio-l,3,~-trir~ietli;vlbenzene ( I ) , \vas chlorinated photochemiFLUORINATIONS c d l y in carbon tetrachloride solution for 35 hours a t 80" C. Two An electrically heated lfonel nutochve of 1.5-litcr c:ipirity, Iiiiiidi~edfifteen grams (0.18mole) of 2-fluoro-1,3,5-tris(trichloronirt1iyl)benzene (melting point, 130-131 ' C.) were obt:iined, the capable of withstanding 11,000 pourids prr q u : I i ' c inrli hydroyield beiiig 95r;. static presure (cold-tested), n-as used in thi? \\-orl.;. This nutric l a w \vas equipped with n reniov:ihle liend arid mouiiteti \\-itIiin T\vo liuii(1red t\vo gram> (0.45 mole) of 2-Huoro-1,3,5-tris(tricliloronirtli~-l)heiizelieIvere mixed n.ith 362 grnnis (2.05 moles) a shelter of '/?-inch iron plate. Only valve h:iiidIe~,g:igw, and exhaust lines were exposed to the operator. Thtw prec:rntion:: (IC nntimouy trifluoridr, :ind the mixture RSII plnced in a n autowere taken for safety of the operator in case of niec1iniiic:il i:iilure clnve. T h i r t y grams (0.10 mole) oi nntiriiony peiit:icliloride ~ v e r entlded, and the autoclave \\-:is heated at 200' C. for 20 tiorlrs. o f any part of the system. Itc~ctificntionof the purified product yielded 57 grams (0.19niolr) X h e n hydrogen fluoride alone \vas employed as tlie fluorin:it iiig of 2-fluo,o-1,3,3-tl.i.(tri~~iornmeth~-l)l~eii~eiie (boiling point :it agent, the material to be fluorinated TWS poured into tire :Illtoclave and the head fastened in place. The d e ~ i i w l:imoiiirt of 753 nini., 120-127" C . ) . The yield w:i.. 4 3 7 . S ~ i i : i t l ~ i o i ~ o n i i ~ ~ i n-us t ~ l c ifound ie t o be quite st:ihle to many hydrogen fluoride v a s iiit,roduced from a 600-nil. iron ccirit:\iiirr lit,. The follu\ving experiment is illustrative of tlie irrertfitted n-ith a brass needle valve, n-hich \vas c o n n e c t r ~ lto tlic. fluorination equipment; the transfer x:is i:icilit:itPd hj- 1ie:iting i r w x of tlic compounds of this type: Trii g r m i i of noli:ifliioromc,sitylerie Tvere plnced in a 200-ml. round-bottom fl:i8 grams of scrubber. The liquid product \vas poured from the autoclave irou:ifiuor(inie~itylene(boiling point, 11s-120 a C.) were i)htnined and combined Jvith material collected in tlie scrub1)ing system from this oprrntion, the compound is evidently riot re:idily oxand cold trap. If antimony salts TYere used in fluorination, they idizctl uricler the condition o f the espwimeiit. n-ere removed from the product by lyashing x i t h coiiceritratrd The, fiiiorin:ited conipourids were purified h y cureful rcctificnhylrochloric acid. The product was m:ide allinline n.ith sodium tion i n a I'odbielriinli column. The physical constuits :ire listed hydroxide nnd steam-distilled. The water-insoluble distilhte in T:ihle I. was then separated, dried with anhydrous calcium sulfate, :rnd rectified. .ACKNOWLEDG.\IENT For the synthesis of 1,3,5-tria(trifluoronietliyl)t~e1i~~ii~~, 269 grams (0.63 mole) of 1,3,~-tris(trichlorometliyl)t~~11~e1ie Lvere The :iuthor\ \\.ish to espress their appreciation to tlie I'urdue poured into the autoclave, and 350 grams (17.5 moles) of :inhyTlehe:irch Foiuidntion For drfraying the expenses o f the initial drous hydrogen fluoride added. The autoclave was then heated part of this investigation arid to the United Stntes S:ir:tl Iteat 200" C. for 20 hours, pressure in the reactor rising t o 2200 search IJ:iboratory for financial assistsnce in completing the inpounds per square inch during fluorination. Rectification of the vestigation. purified reaction product yielded 86.7 grams of material boiling in the range 119-120' C. at' 750 mm. mercury pressure, which n-as LITERATURE CITED identified as 1,3,5-tris(trifluoromethyl)benzene. The yield ~vne ( I ) Rlaa, G., and Schiemann, G., Ber., 60, 1186 (1927). 495. (2) Fittig, H., Ann., 150, 328 (1869). 2-Chloro-, 2,4-dichloro-, and 2,1,6-trichloro-1,3,5-tris(trifluoro(3) I. G. Farbenindustrie A,-G., French Patent 798,727 (193G) methy1)benzenes n'ere prepared from the corresponding 2-chloro-, 2,4-dichloro-, and 2,4,6-trichloro-tris(trichloromethyl)benzenes ABSTRACTED from a doctoral thesis of R. E. Leech, submitted t o the faculty in a manner similar to that described for the preparation of 1,3,of Purdue Gniversity.
