INDUSTRIAL AND ENGINEERING CHEMISTRY
412
Vol. 39, No. 3 ACKNOWLEDGMENT
T . ~ B LS'I. E
~'REI'ARITION OF 1 , l - ~ I F L ~ o R O - 2 - C € I L O R o E T I I . k S ~ ~
13 100-5
10
Expt. S o , T e m p , C. Time, hours Reagents, moles
2f.o CHC12CH2C1 Mole ratio, HF:CHClsCHICl Product obtained CHFsCHsC1, moles Per cent C H C l F C H L 2 , moles Per cent CHFsCHsF, moles Per cent C H C h C H L l recovered, nioles Conversion to fluorinated product,
23-h
16
14
05 69
125
1.4i
15 13.0
12 5
PO 5
"0
1 0 9.0 1 0 9.0
1 5
1.0
1.5--
7.0 1
. 7
4.66
0 512 52 0.117 12
5%
15 100
37 89
100
0 0 0.015 64
11 5 1 0 11 5
14 ( 3 1.5 0 84
0 627
0 01
0 507 32 0.276 19 0 0 0 019
64
61
0.056 6 0 0 0.0136
0.232 0.029
51
io
78
15 1
0
per square inch. Conditions required for these high yields arc about 100" C., about 36 hours, and a molar ratio of HF to HgO to CBrCl2CH@r of about 15 to 3 t o 2. Shorter reaction periods and reduced teniperatures are productive also of CCIF?CHyBr a n d CC12FCH2Br. T h e latter compound had been obtained previously by the same reaction (11 ) . The starting compound, CBrC12CH2Br, was prepared by addition of broiiiine to GCl,=CH,. T h a t compound CCIFzCHzBr (boiling point, 65-66' C.) was prepared from CF2=CH2and bromine chloride a t 0' C. The CFy=CH2was obtained as a product of the dechlorination of CC1F,CH2C1 n.ith powdered zinc in acetamide and butanol at 50" C. T h e CF,=CH2 distilled into bromine chloride at 0" as soon as formed. Conversions to the new compound iverp about 15%.
17 45 1 33 13 1
0,997 79 0 0 0 0 0.06
The authors n-ish t o acknowledge the financial assistance of E. I. du Pont de Semours &. Company, Inc., and the llallinckrodt Chemical Works which made this research possible, and t h e aid of G. Hueschen in preparing the manuscript.
14.5
1.61
8 06
0,548 34 0.30 19 0.167 10 0 012 63
LITERATURE CITED
(1) Benning, A . F., U. 9 . Patent 2,230,925 (1941). 79 (2) Henne, A. L..J . Am. Chem. Soc.. 60, 1569-71 (1938). (31 Henne. A. L.. and Hubbard. D. M.. Ihid., 58, 404-6 (1936). (4) Henne, A. L.. and Plueddeman, E. P.. Ibid., 65, 1271-2 (1943). (5) Henne, A . L., and Renoll, Mary, Ibid., 58, 887-9 (1936). (6) Ihid.,58, 889-90 (1936). (7) Henne, -4.L., et al., Ibid., 67, 1906-8 (1945). (8) I. G. Farbenindustrie, Brit. Patent 466,509 (1937), French Patent 798,421 (1936); Scherer, O., German Patent 670,130 (1939), U. S. Patent 2,146,354 (1939). ( 0 ) McBee, E. T., unpublished data. (10) McBee, E. T., et al., J . Am. Chem. Soc., t o be published. (11) Renoll, Mary, U. S. Patent 2,344,061 (1944). (12) Itohbins, B. H., J . Pharmacol., 86, 197-204 (1946). (13) Swarts, F., Bull. acad. roy. Belg., 1902, 731-60. (14) Swarta, F., Bull. soc. chim. Belg., 43,471-81 (1934) ; Compt. rend. 197, 1261 (1933). PRESESTED hefore t h e Division of Organic Chemistry :it the 100th \Ieetinc of the . ~ E R I C . A KC H E V I C ASOCIETY, L Atlantic City, X, J. The major portion of this paper i ? taken f r o m a doctoral thesis submitted to the faculty of Purdue L-niversity by W. h.Bittenbender.
FLUORINATED ETHERS Earl T. 31cBee and Robert 0. Bolt' PURDUh UYIVERSLTY A \ D PLRDLE RESE4RCH FOUYDATIOY, LAFiYETTE, I Y D .
CERT -IIN aryloxy -2,2-dichloro-l, I-clifluoroet hanrs ha\ e been prepared by the action of 1,2,2-trichloro-l,l-difluoroethane on anh~drousalkali metal aryloxides in a solFent. In a similar manner, an aryloxy -2-chloro-l,l-difluoroethane and an aryloxy-2-chloro-1-fluoroetharie here prepared. The action of 2-chloro-1,1,1,3,3,3-hexafluoropropane on an arylol in the presence of sodium hydrotide yielded an aryloxy-2-chloro-l,l,3,3,3-pentafluoropropane and an aryloxy 2 chloro 1,3,3,3 tetrafluoropropene. Rlethods of preparation and physical properties of the compounds are given. Evidence is presented to support the postulated structure of these compounds. .-I new and convenient method of synthesizing 1,1,1,2-tetrachloro2,2-difluoroethane is reported.
-
-
-
-
C
Sivarts (9, 11 13) prepared n1koxy:polyfluorohalo)alkanes by the action of alkanolic caustic solutions or metallic alkoxides on (polyfluoroha1o)alkanes. Gowland (1) extended this procedure. Swarts ( 12 ) dehydrohalogenated alkoxy(polyfluoroha1o)alkanes to alkoxy(polyfluorohalo) alkenes. In the present work aryloxy-2,2-dichloro-l~l-difluoroethanes, nryloxy-2-chloro-l,l-difluoroethane:,and aryloxy-2-chloro-l,1,3,3,3-pentafluoropropanes were prepared from an alkali metal 1,2-dichloroaryloxide and 1,2,2-tricliloro-l,l-difluoroethane, 1,l-difluoroethane, and 2-chloro-1,1,1,3,3,3-hexafluoropropane, respectively. Aryloxy(fluoroch1oro)alkenes resulted from dehydrofluorination of the parent ethers. Dechlorofluorination of aryloxy-2,2-dichloro-l,l-difluoroethanenyielded aryloxy-2-chloro-I-fluoroethenes. Table I lists the compounds and their physical properties
ERTAIS aryloxy(polychlorofluoro)ethanes, -ethenes, -pro-
panes, and -propenes have been synthesized. Because of their wide liquid ranges and tendency tolvard nonflammahility, t h e ncn- compounds are of interest, as possible heat transfer fluids. An electron sharing center, such as the oxygen atonia, m a y also be desirable, since dative bond foriliation betiveen this center and metallic atonis of a heat, transfer n-all should effect an e%cient exchange of heat. The ar!-loxy(polvclilorofluoroiallianr.. are capable of forming intermolecular lij-drogen bonds; tlii. property should also be advantageous in a heat transfer ngcnt. T h e ethers may also be useful as dielectric media. 1 Present address. California Research Corporatioil ;a >iit>sidiars oi tlic S t s n d a r d Oil C o n i p a n j - ) , Richmond, Calif.
STARTING R I T E R I A L S
.\I ET-ALLIC ARYLOXIDES.Cresols vere of technical grade; phenol and 1-naphthol w r e L-.S.P. grade. 3-Trifluoromethylphenol (boiling point, 68-69" C. at 12 inin.) n-as synthesized by the method of Sn-arts (10). hiihydrous a l k d i nretal aryloxides xvere niade hy mixing equiinolar quantities of arylol and metallic hydroxide and removing water by azeotropic distillation u.ith benzene or toluene. Benzene it-as weti in preparing anhydrous 3-trifluoromet~i~lplienoxidea. !POLE.CHLOROPI.UOKO)ALE(ISE~. 1,2,2-Trichloro- 1,l-difluoroethane (b.p. 7 2 " C . ) ( 3 ) , 1, 2-dichloro-1,l-difluoroethkne (h.p.
INDUSTRIAL AND ENGINEERING CHEMISTRY
March 1947
TABLE I.
PHYSICAL PROPERTIES O F .iR\ L O X Y ( P o L Y C H L O R o F L U O R ~ ) . 4 L K A Z E SAND -ALKEKES
B.P.,c. 740 mm." 216.0 230.0 230.5 233.5 211.0 196.0 213.5 217.0 216.5 197,O 188.0 278.5 ?: 210.0 189.5 204.5 209.0 212.5 189.5 184 5 'E3 275.0 .ihsolute values accurate t o 0.2' C . Formula
0
b c d
413
4 mm.b 67.9 77.5-78.Od 77.9-78.4d 79.8-80.3d 64.2-64.7d 55.8 66.0 69.8-70.0 69.6-70.2 56.6-56.9 47.3 105.0-106 0 63.0 49.7-49.8 59.3 64.0-64 4 63.6-64 2 50.0-52 0 43.2-44.1 10?.0-103.0
c.
lI.I',C, -23 5 to - 2 4 . 0 -18.0 to - 2 0 . 0 Pets t o a glass -13.0 t o -16.0 Sers t o a glass ,-50 0 to -52.5 -32 0 to -35 0 Pets to a glass Sets t o a glass -41.0 t o -43.0 -32.0 t o -35.0 -10 0 to -13.0 -42.0 t o -44 5 -50 O r o -51 0 -38.5 to -39 0 Sets t o a glass -40 0 t o -41 5 -63 0 f o - 6 4 0 - 5 3 oto -56 0 10 5 t o 13 0
d:' 1 ,3706 1.334 1.322 1.320 1,485 1,2704 1,2388 1.2325 1.2222 1.4177 1.4112 1,4220 1.3364 1.22il 1,1903 1,1880 1.1854 1,3909 1.3073 1,3859
ng,
%C1 % F 1.4789 31.2 16.7 29.5 15.8 1.485 29.5 15.8 1.482 29.5 15.8 1.481 1.437 24.5 32.2 1,4777 18.4 19.7 1,4758 17.2 18.4 1.4731 17.2 18.4 1.4732 17.2 18.4 1,4255 13.6 36.0 1.4216 13.6 36.5 1.5071 11.4 30.6 9.2 1.5162 34.3 1.5049 20.5 11.0 1.5067 19.0 10.2 1.5031 19.0 10.2 1,5032 19.0 1 0 . 2 1.4454 14.8 31.6 1.4513 14.8 31.6 1,5295 12.2 26.1
Mol.wt. 227 241 241 241 295 192.5 206.5 206,5 286.5 260.5 260.5 310.5 207 172.5 186.5 186.5
186.5 240.5 240.5 290.5
% C
31.2 29.3 29.4 29.5 24.6 18.4 17.1 17.2 16.9 13.4 13.2 11,.6 34.2 20.3 18.9 18.7 18.8 14.4 14.6 12 6
Observed __ % F .1Iol. w t . 224 17.4
15.0 14.2
240 247
15.5
'38
33.0 20.1 18.7 19.0 18.9 37.1 36.6 30.9 9.0 11.7
304 191 206
204 308 261 257 310
206 172
10.6
1 85
10.5 10.7 31.9 31.4 26.3
186 185 243 236
284
Obseri-ed values subject to errors incurred i n measuring pressure with Ziiinilerli iI>anoiiieter. ;\hsoluie \-due5 accurate t o 0 5' C . Ilztiinated f r o n i vapor-pressure slide rule [AIiIeq, I X D .ET[.. C H E L ,35, 1052-61 (1943,) b y w e of reduced-pressure boiling point data f o r C6HaOCI'?C'€ICI2.
47" C.'; ( Z ) , and 2-rliloro-1,1,1,3,3,3-hexnfluoropropane (ti.p. 14-15' C. a t 740 mni.) ( 7 ) were prepared by known methods from pentachloroethane, 1,1,1,2-tetrachloroethane8and 1,1,2-trichloro3,3,3-trifluoropropene ( d ) , respectively, 1,1,1,2-TETR.iCHLORO-2,2-DIFLUOROETH.&XE. Several methods for the synthesis of this compound have been reported ( 2 , 5 ,6, 8 , I S ) . In the present n-ork, 1,1,1,2-tetrachloro-2,2-difluoroethane vias prepared by the exhaustive photochemical chlorination of 1,2,2-trichloro-l,l-difluoroethane. Starting material was placed in a long vertical glass tube fitted n.ith a dispersion disk for the introduction of chlorine, and illumination provided by incandescent lights placed alongside t h e tube. During chlorination, the reaction temperature was maintained between 63" and 92" C. PREPARATION OF ETHERS ARYLoXY-2,2-DICHLORO-1,1-DIFLUOROETH.4SES.
From
1,2,2-
Trichloro-1,I-dijuoroethane. A general procedure applicable t o the preparation of all members of the series was developed. 1,2,2-Trichloro-1,l-difluoroethanewas added dropwise to a cooled solution of a sodium aryloxide in acetone, contained in a glass flask fitted n-ith a sealed stirrer, reflux condenser, and thermometer. Equimolar quantities of reactants were used, and about 200 ml. of acetone per mole of sodium aryloxide \vas sufficient solvent. Cooling was necessary during addition of the ethane derivative. Sodium chloride precipitated as reaction progressed. The temperature \vas maintained a t approximately 15-20 C. during addition to prevent excessive dehydrochlorination of the 1,2,2-trichloro-1,l-difluoroethane t o l,l-dichloro-2,2-difluoroethene. After addition rvas complete, the temperature was raised sloirly and the solvent refluxed for several hours. Immediate reaction did not occur n-hen sodium 3-trifluoromethylphenoxide and 1,2,2trichloro-1,l-difluoroethanewere mixed. Inbtead, there was no apparent reaction until a temperature of about 50" C. \vas reached, as evidenced by precipitation of sodium chloride. This sodium aryloxide is the least reactive of any used. The ethers were recovered from the reaction mixtures by distilling off most of the solvent and niaking the rezidue strongly alkaline with about 0.5 mole of sodium hydroxide per mole of phenol in the starting material. T h e ether \ m i then >team-distilled from this mixture. The lower layer of distillate ivas separated, dried n-ith Drierite, and rectified a t reduced pressure (Table I gives boiling points). The aryloxy-2,2-dichloro-l,l-difluoroetlianeswere obtained in 56 t o 79% yields and conversions, calculated on the 1,2,2-trichloro-1,l-difluoroethaneused. T h e (3-trifluoromethy1phenoxy)2,2-dichloro-l,l-difluoroethanewas obtained in lowest yield and
conversion; the highest values were those for phenosy-2,2-di-
chloro-1,l-difluoroethane.S o attempt was made t o recowr unreacted sodium nryloxide in the form of the phenol excrpt in experiments with 3-trifluoromethylphenol. In these, conicrsion of the phenol was f167~and the yield of ether 68%. The lnw yields and conversions of the ethers as calculated from the ethane derivative were due to the formation of l,l-dichloro-2,2-difluoroethene. If anhydrous reactants were not used, much more dehydrochlorination by-product was obtained. From 1,l ,i,~-Tetrachloro-b,2-di$uoroethane.In reactions of equimolar quantities of this ethane derivative and sodium phenoxide, butanone was used as solvent. No immediate reaction was apparent a t room temperature] so heat was applied and t h e solvent refluxed. After about 14 hours, t h e reaction mixture was rectified without further treatment, and an ether isolated in a yield and conversion of about 30%;;. This material was found to be identical with t h a t obtained from l,2,2-trichloro-l,l-difluoroethane and sodium phenoxide. The course of the ether formation involving the fully halogenated ethane derivative is unexpected. Apparently a reduction such as t h e following is involved:
+
CaH50CF2CC1, 2CsHbONa -+ CsHrOCeHdONa C6H60CF&HC12
+
+ NaCl
(1) .ARYLOXY-2CHLORO-~-FLUOROETHENES. F r o m l,b-Dichloro-l, 1-dijuoroethane. hlixtures of ethers containing the same aryloxy group Ivere ohtained when the general procedure, described for the preparation was applied t o the of phenoxy-2,2-dichloro-l,l-difluoroethanes, reaction of CClF2CH2C1with a solution of sodium aryloxide i n acetone. I t ivas not necessary t o add this dichlorodifluoroethane dropwise or to cool the solution of the metallic aryloxide. The reactants and solvent were mixed, and t h e mixture was refluxed for about 6 hours. Some precipitation of sodium chloride was noted after several hours. After the general recovery proceclui~e, an efficient rectification separated pure ethers from the crude product. Considerable dehydrochlorination of 1,2-dichloro-l,ldifluoroethane t o 2-chloro-1,l-difluoroethene occurred; nnhydrous conditions limited formation of this by-product. This ethane derivative appears less reactive than 1,2,2-trichloro-l, 1difluoroethane. An ether was produced from 1,2-dichloro-1,1difluoroethane and 3-trifluoromethylphenol only by use of the more reactive potassium salt. Saturated and unsaturated ethers were produced in about equal yields and conversions. Relative amounts varied with conditions used in steam-distillation recovery from the reaction product-for example, basicity and speed of distillation. Phen-ARYLOXY-2-CHLoRO-l,1-DIFLUOROETHAXES A S D
414
INDUSTRIAL AND ENGINEERING CHEMISTRY
oxy ethers rrere obtained in about 50% yieldi, o t h r r ttliera i i i about' 3570 yields, based on t h e ethane derivative consumrd. T h e low values are consistent x i t h t h e relatively large amount of dehydrocblorination product obtained from the l12-dichloIo1,l-difluoroethane starting material in these experiments. The increased deliydrohalogenation is probably due t o the hig1ic.r temperatures necessary t o favor formation of ethers in this series. Anhydrous materials were necessary in all case; to suppress tlie competing dehydrochlorination reaction. Dehalogenation of Phenoxy-b,2-dichlo~o-l,l-di~uoroethane.-1 mixture of this ether (0.22 mole, 50 grams), zinc powder (0.75 niolr, 50 prams), and 95% ethanol (150 ml.) was refluxed in a glas. flask for 33 hours. T h e product was steam-distilled, and the lower layer of distillate separated, dried Yvith Drierite, and rectified in a vacuum. A 70% yield and conversion to phcnoxy-2chloro-1-fluoroethene (0.15 mole, 26.5 grams) %as obtaitird. Dehydro.fluorination of Phenoz?j-b-chloro-l ,l-diJluoroe:iiarie. Thc: halogenated ether (0.47 mole, 91 grams), zinc povidor (1.0 molc~, 6 3 grams), acetamide (2.07 moles, 122 grams), antl pot (0.07 mole, 12 grams) were mixed in a glass flask equipped \I itli :i sealed stiri.er,reflux condenser, and thermometer. The tc~niperaturf. was inaint~aineda t 130" to 150" c. for aboat 20 ~ i o u r -b i t h constant stirring. After cooling, water \vas a d t l d , tlie react ion mixture filtered, and the lower layer of liquid wllaratctl. Thimatrrial \vas dried and rectified under reduced pressure. Phriiosy2-chloro-1-fluororthene was the only product, imlated (0.20 inolc. 35 grains) ; yield and conversion were 43%. P H E N O X Y - 2,2-DICIILORO - 1- F L U O R O E T H E S E . Phf!n(JX,l'-2,2-tiichloro-1,l-difluoroethane (0.44 mole, 100 grams) and trini~tliylbenq.1 :unmoniun~ hydroxide (10 grams) Ivere niixrd rvith 2 I O ml. of water in a glass flask fitted with a sealed Ftirrcr, reflux C O I I denser, and thermometer. Potassium hydroxide \vai dissolved in the mixture until the densities of the two layers n-ere aijout equal. The resulting material vias refluxed for 16 hour., tile product steam-distilled, and the lower layer of di,tillstc strl)arated. The aqueous phase of distillate was extracted with C ~ I ~ O I Y J form, and the extracts were added to the organic layer prior to drying and rectifying. Pl1enoxy-2,2-dichloro-l-fluoroethene as t,he only product obtained (0.125 mole, 26 grams) ; ronversioii and yield were 289& ARYLOXY2 - CHLORO- 1,1,3,3,3- PESTAFLUOXOI'ROI'.\\~;'~ AYI) ihYLOXY-2-CHLORO- 1,3,3,3-TETRAFLCOROPROPE S E 9 . A 1ixt UYCS Of ethers containing the same aryloxy group TTere prepared by heating a n acetone solution of equimolar quantities of 2-chloroI ,1,1,3,3,3-hexafluoropropane, the arylol, and sodium hydroxide in an iron autoclave a t 170" C. The autoclave x a s constructed t o withstand a pressure of 6000 pounds per square inch a t 200" C., and \vas provided with means of heating and rocking. Reaction time was about 8 hours, after which t h e product was treated in a manner similar to t h a t described for the isolation of the aryloxy2,2-dichloro-l,l-difluoroethanes.Conversions and yields, based o n the propane derivative, were about 20% for t h e phenoxy-2chloro-1,3,3,3-tetrafluoropropeneand 39% for t h e phenoxy-2chloro-1,1,3,3,3-pentafluoropropane. T h e higher boiling 1naplithoxy derivatives were obtained in a 3 t o 2 ratio of unsaturated to saturated, but in much lower conversions and yields. ACTION OF ALKANOLIC CAUSTIC SOLUTIONS OK PHEIVOXY-
(POLYCHLQROFLUOR0)ALKANES A~~ethU?ZOl. P I l E X O X Y - 2,2 - DICHLORO - 1,1- D I F L U O R O E T H A T E . T h e ether (0.11 mole, 25 grams) was mixed Jvith ~jotassiumhydroxide (0.48 mole, 27 grams) and ahsolute nlethanol (100 ml.) in a glass flask, and refluxed for about 24 hours. Water was then added, and the resulting lower layer separated, washed v-ith water, dried, and rectified under reduced pressure. Practicnlly all of the product (18 grams) boiled a t 84" t o 86" C. at 6 mm. pressure. This colorless liquid is believed t o be 2,2-dichloro-lmethoxy-1-phenoxyethene (0.083 mole, 7573 yield and conversion).
Vol. 39, No. 3
Analvsis: Calculated for (C~ILO)CIOCHA=CCL. 32.4% C1. 219 mdecular weight; found, 3 2 2 % C1, 2f4 mol. wt. Biilini point, 233" C. at 740 mm.; melting point, 11-13" C.; d:' 1.276; n1,0 1.519.
Ethanol. Phenoxy - 2,2 - dicliloro - 1 , l -difluoroethane (0.048 mole, 11 grams), potassium hydroxide (0.27 mole, 15 grams), antl 05% ethanol (105 ml.) were placed in a glass flask. This mixt'ure \?as refluxed for 31 hours before being treated in t h e manner just described for the methanol experiment. About 6 grams of product were obtained (boiling point, 109-110" C.) a t 5 mni. \vhic-h \\-as believed to be 2,2-dichloro-l-ethoxy-l-phenoxyethene. rindysis: Calculated for ( c , H j O ) c ( o c z ~ ~ j ) = c c l 30.2% ,, c1; found, 30.3y0 Cl. Boiling point, 180" C.; melting point, sets t o a glass; d:' 1.231; n'," 1.527. P H I : S O X Y - ~ - - C I I L O R O - ~ , l - D I F L U O R O I ~ T ~ I A N E . This ether, when mixed with an equimolar quantity of potassium hydroxide anti O5y0 cthanul, gave a sinall amount of product which containetl clilorine but no fluorine. DEHYDROFLUORIN.~TION O F ARYLOXY - 2,2- DICFII,
