I
D. D. SMITH, R. M. MURCH, and 0. R. PIERCE Dow Corning Corp., Midland, Mich.
Fluorine-Containing Polyethers These polyethers possess good solvent resistance to most commonorganic solvents, but cannot be vulcanized to rubberlike materials
T HEstability and solvent resistance of highly fluorinated polymers have been amply demonstrated by the wide use of Teflon (polytetrafluoroethylene) and KelF (polychlorotrifluoroethylene) in applications where other polymers were unsuitable. The use of such polymers in elastomeric formulations is limited, however, by the fact that they are comparatively rigid a t lower temperatures. The incorporation of an ether linkage in such a molecule might-by allowing bondsrotation about the - C - 0 - 4 -
improve the low temperature elasticity, but retain stability and solvent resistance. Thus fluorine-containing polyethers appeared to offer a challenging field for research. A survey of the literature indicated the feasibility of synthesis of fluorinecontaining monomers for the preparation of polyethers, although little information was found regarding the fluorine-containing polymers themselves. Inasmuch as the polymerization of epoxides appeared to offer the most expedient
route, that procedure was chosen as the first method of approach to the problem. [After completion of this work, Hauptschein and Lesser ( 7 7) described preparation of fluorine-containing polyethers by a different procedure.] The first fluorine-containing monomer selected for polymerization studies was 3,3,3 trifluoro - 1,2 epoxypropane. This previously reported epoxide (77) was prepared as follows:
-
-
CFaCOCHzBr (1) Literature Survey Method of Preparation
Compound
r-?
7
1
+ H F or KF
CHzFCHCH20
CHeCICHCH20
r-i CFaCHCHzO
CFaCHOHCHzBr f NaOH
-r
1
CrFrC(CHa)CHz0
r
i
CFaCHCHFO
+ NaOH
C3EiC(OH)(CHs)CH~Cl
CFsCOCHzBr
(9, 16)
CFsCHOHCH2Br (2) CFaCHOHCHrBr
(211
CFaCHOHCHFBr -t NaOH
The analogous epoxides, 2-methyl3,3,3-trifluoro-1,2-epoxypropane and 1c h l o r o-2-me t hyl-3,3,3-t r i f l u o r 0-1,2epoxypropane, were also synthesized, using the reaction sequence:
r-i
r-i
CFzClCFCCIzO CFaCFCFzO
CFiCOzH CFZCICCI = CClz CFzClCF = CClz
+ CH30H
+
CFaCOzCHa (4)
+ 02 +02
+
n CHzClCHCHzO
+ NaOH
(17)
CFzCHzO CFzClCClCCIz~
+ LiAlH4
Reference
+ HF/elect.
($6)
CFiC(OH)(CHa)z Clz CFaC(OH)(CHzC1)CHs CF3C(OH)( CHC1z)CHa ( 6 ) VOL. 49, NO. 8
0
+
+
AUGUST 1957
1241
CFsC(OH)(CH&l)CHa
+ NaOH
alcohols were decomposed, losing hydrogen fluoride about as readily as hydrogen chloride. No epoxide was isolated and no alcohol was recovered. CF&(OH)(CHCla)CH3 NaOH Two other synthesis routes were inves1 tigated-preparation of the intermedi(50% as.) CF&(CHs)CHClO ( 8 ) ate halohydrin by addition of a hypohalous acid to a fluorine-containing oleT h e structure of the chlorine-containfin, and direct peracid oxidation of a ing epoxide was confirmed both by fluorine-containing olefin to a n epoxide. infrared and mass spectrographic analyTwo olefins were employed in each of ses, which in turn permitted definite these procedures: 2-methyl-3,3,3-tricharacterization of the dichloroalcohol. fluoropropene. by dehydration of 2I n an effort to increase the yield (2097, methyl-3,3,3-trifluoro-2-propanol; and average) of 2-methyl-3,3,3-trifluoro-1,2- 3,3,4,4,5,5,5 heptafluoro - 1 pentene, epoxypropane from the starting by dehydration of 3,3,4.4.5,5,5-heptafluoroacetic acid, an alternative fluoro-2-pentanol which was obtained cedure was investigated. either by addition of methylmagnesium halide to heptafluorobutvraldehyde or CF~COCHIf Brs + CF3COCHeBr reaction of methyl heptafluorobutyrate with mixed methyl and isopropyl magnesium halides (25). CFsCOCHsBr CHaMgBr A literature survev of the methods for CF&(OH)( CH2Br)CHa adding hypohalous acids to olefins disclosed many references to this type CFaC(OH)(CHsBr)CHs -I-NaOH of reaction, but onlv one (7) pertaining to fluorine-containing olefins Applica(50% as.) -+ CFs&(CHs)CHzO tion of the method of Madesch (75), involving the zn sztu formation of hypoHowever, this procedure produced chlorous acid in the presence of the olethe epoxide in over-all yield of 2070, fin, failed with both of the Auorine-conand as the bromohydrin was not very taining olefins. -17-Bromosuccinimide, stable with respect to heat, its purificarecently reported to be an excellent tion was difficult. This approach apreagent for the addition of hvpobromous peared to offer no advantage over that acid to olefins (70), likewise failed to via the chlorohydrin, and it was not yield a bromohydrin. The addition of studied extensively. However, a simihypochlorous acid as described by Colelar procedure has been successful ( 78). man and Johnstone (6) was also unsucOther chlorofluoro alcohols were precessful when 3.3,4,4,5,5,5-heptafluoro-1pared for investigation as possible epoxide pentene was used; with 2-methyl-3,3,3intermediates: 2 chloro - 2,2-difluorotrifluoropropene an addition product ethanol, 2,2,-dichloro-2-fluoroethanol, was obtained. This product was a 1,3 dichloro - 1,1,3,3 tetrafluoro - 2mixture, part of which was a solid meltpropanol, ~,3,3-trichloro-l,l,3-trifluoro- ing at 45' C. The impure mixture, 2-propanoh and 1,3-difluoro-l,1,3,3however, yielded some epoxide when tetrachloro-2-propanol. The first ~ W Q treated with hot, 507' aqueous base. were prepared from the chlorofluoro acids The peracid oxidation of olefins to via the acid chloride, followed by reducepoxides is well known (28). This tion with lithium aluminum hydride. method eliminates the preparation of an The latter three were prepared by reducintermediate halohydrin, and for that ing the corresponding chlorofluoroacereason a study of the method was incortones with lithium aluminum hydride. porated into this program. No report Attempts to epoxidize these alcohols could be found in the literature on the resulted in failure. When heated with extension of peracid oxidation to fluoa strong, aqueous inorganic base, or rine-containing olefins; but it is known with an organic base (quinoline) the that negatively substituted olefins resist (50% aq.)
-+
CF3&(CHS)CH;b (7)
+
-
-
-
-
+
-
-
-
this type of oxidation. The reaction of perbenzoic acid or peroxytrifluoroacetic acid with 2-methyl-3,3,3-trifluoropropenc did not yield an oxidation product. Initially, polymerization studies were conducted to determine the most suitable catalyst for polymerization of the monomer epoxides. For various reasons, only Lewis acid-type catalysts were considered a t the start, although later experiments showed that free radical catalysts-e.g., benzoyI peroxide, tert-butyl hydroperoxide, and cobalt-60 irradiation-did not promote polymerization. The results of the acid catalysis studies are shown graphically in the figure; aluminum chloride and ferric chloride are the most efficient catalysts for 3,3,3-trifluoro-1,2-epoxypropaneor 2 methyl - 3,3,3 - trifluoro - 1,2epoxypropane, in so far as conversion of monomer to polymer is concerned. Only meager data were obtained for the chlorine-containing epoxide, and these indicated that rate of polymerization was slow and conversion to polynier was poor. The use of aluminum chloride with either of the other epoxides resulted in rapid polymerization, and high conversion from monomer to polymer. However, the degree of pol>-merization apparently was low, because only viscous liquid polymers were obtained. Ferric chloride catalysis was markedly different. The rate of pol>merization was slower, compared with aluminum chloride catalysis. With 2-methyl- 3,3,3trifluoro-I ,2-epoxypropane only liquid polymers were formed, but solid polymers were obtained from 3,3,3-trifluoro1,2-epoxypropane. If the polymerization was conducted over a long period of time-e.g., 64 hours--less catalyst was required to give the same (24 hours) conversion and the molecular weight of the polymer was increased. Thus, with 2 to 3 weight yo of ferric chloride, at 90 to 100" C. for 6 4 hours, polymers having a weight-average molecular weight of 230,000 were obtained from 3,3,3-trifluoro-l,2-epoxypropane. Copolymerizations of the epoxides with ferric chloride catalyst were investigated also. The copolymers thus obtained varied in physical appearance ~
Physical Properties of New Compounds Analytical ~~
nF
Q5
F, %
Calcd. C1, 70
C, %
Found ______ F, % C1, % C, % '
CFsCOH(CHKX) CHI
116.0
1.3755
1.396
27.1
26.8
35.1
21.8
29.5
35.1
22.6
29.5
CFsCOH(CHCl2)CHa
136.0-137.0
1.4036
1.525
32.0
31.7
28.9
35.6
24.3
29.6
36.1
24.4
CFaC(CHa)CHaO
54.5-55.0
1.3128
1.191
20.4
20.6
45.2
..
38.1
44.8
.+
37.2
CF,~(CH~)CHCIO
65 5-66.0
1.3428
1.322
25.2
25.8
34.5
22.1
29.9
34.7
22.5
30.4
Compound
7
1242
B. P.,
e.
MRD Calcd. Found
1
I
INDUSTRIAL AND ENGINEERING CHEMISTRY
FLUORINE-CONTAINING POLYETHERS
100
90 80 70 60
50 40
30
20
IO
2
I
3
WT.%
4 .
5
CATALYST
Effect of catalysts on polymerization of 2-methyl-3,3,3-trifluoro-lr2-epoxypropane and 3,3,3trifluoro- lr2-epoxypropane 1 gram of epoxide, 80' t o 100' C., 24 hours
1)
from the characteristic solid of the 3,3,3-trifluoro-1,2-epoxypropanehomopolymer, through waxy solids and viscous semisolids, to viscous liquids as the concentration of 2-methyl-3,3,3-trifluoro1,2-epoxypropane was increased. The liquid homopolymers proved to be excellent low load lubricants, with indications that they might have utility in the extreme pressure range (see Table I). This property may be enhanced by some halogen intersubstitution with the catalyst. Several attempts were made io convert these liqyids to solid polymers by reaction with such reagents as hexamethylene diisocyanate and maleic anhydride. However, the Yesults of such experiments were not promising. The solid polymers obtained by the ferric chloride-catalyzed polymerization of 3,3,3-trifluoro-1,2-epoxypropaneand the copolymers of that epoxide with 2methyl 3,3,3 trifluoro 1,2 epoxypropane possessed good thermal stability and were insoluble in aromatic or highly chlorinated solvents. Thus, they were subjected to vulcanization studies, to determine their possible utility in rubber applications. Tests were conducted using peroxides and isocyanates on formulations of the polymers with fillers; on blends of the polymers with fillers; and on blends of the polymers with polydimethyl siloxanes and fillers.
-
-
-
-
A rubberlike material resulted only when a siloxane was incorporated. Even in this case, it was felt that the rubbery qualities were imparted by the siloxane, and that the polyether did not vulcanize. While vulcanizates of this type possessed increased solvent resistance, their tensile strength was considerably poorer than that of an updiluted polysiloxane. One series of experiments was designed to incorporate fluorine into the polyether chain, in an attempt to prepare a fluorine-containing polyglycol formal as described by Hill and Carrothers (73). The reaction of dibutyl formal with 2,2,3,3,4,4, - hexafluoro 1,5 pentanediol resulted in the formation of a high boiling liquid which decomposed on long standing, or upon heating at atmospheric pressure, liberating formaldehyde and the original glycol. Presumably the product was a monomeric or dimeric cyclic formal.
-
-
Experimental 3,3,3 Trifluoro 1,2 epoxypropane. Trifluoroacetone was obtained from the Peninsular ChemResearch Co., Gainesville, Fla. It was brominated and reduced to 1-bromo-3,3,3-trifluoro-2-propanol according to the procedure described by McBee and Burton (77). The epoxide was prepared from the bromo-
-
- -
hydrin by the procedure of McBee, Pierce, and Kilbourne (20).
2-Methyl- l,l,l-trifluoro-2-propanol was prepared by the reaction of methylmagnesium bromide with methyl trifluoroacetate. Henne, Shepard, and Young (72) reported 97% yield of this alcohol as its azeotrope with ethyl alcohol by the use of ethyl trifluoroacetate, while Swarts (27) employed the amyl ester. By using methyl trifluoroacetate, the pure alcohol (boiling point 80-82' C., ng 1.3329) was obtained in 69% yield. 2-Methyl-3-chloro-1,1,l-trif3uoro-2propanol. Procedure A. T h e procedure employed was similar to that reported by McBee, Pierce, and Marzluff (27). The chlorination apparatus consisted of a vertical tube 51 mm. in diameter and 600 mm. in length, sealed at the lower end. A heating element of Nichrome ribbon was wrapped around the lower 150 mm. of the tube. T h e upper end was sealed with a neoprene stopper through which the following were fitted: a condenser connected to a dry ice-cooled trap, a thermometer well, a helical cooling coil, and a gas dispersion disk. T h e latter three extended to the bottom quarter of the tube. Chlorine was fed to the glispersion disk through a system comVOL. 49, NO. 8
a
AUGUST 1957
1243
Table
1.
1.3585, MRD calcd. 17.8 (found 18.3); and 2,2,-dichloro-2-fluoroethanol, boiling point 119-23' C., n55 1.4155, M R D calcd. 22.7 (found 23.7).
Shell 4-Ball W e a r Test Results
(52-100 standard steel balls, 1200 r.p.m., 275O F., 2 hours)
'Polymer (Liquid)
4-kg. load
[CFaC(CHa)CHzO12 ( C R C HCH20) z
0.52 0.32
Scar Diameter, Mm. 10-kg. load
.. 0.33
40-kg. load a .
0.61
-
-
-
-
1,3 Dichloro 1,1,3,3 tetrafluoro 2propanol; 1,3,3-Trichloro-l, 1,3-trifluoro-%propanol; a n d I2i,3,3-Tetrachloro-1,3-difluoro-2-propanol. The corresponding chlorofluoroketones (contaminated somewhat with isomers) were obtained from the General Chemical Division and reduced with lithium aluminum hydride. The resulting chlorofluoro alcohols were not pure (CFZClCHOHCF&l boiling point 113-114' C . , nk5 1.372; CFzCICHOHCFClz boiling point 143-4' C., n&5 1.416; CFClaCHOHCFCI, boiling point 77-78', ng 1.458) because of contarnination with their isomers. Howevar, they were sufficiently pure for epoxidation attempts, which was the principal reason for their synthesis. When these alcohols were treated with hot, aqueous sodium hydroxide or with refluxing quinoline they were decomposed completely.
prised of a dry ice-cooled trap, a safety propane. From 126 grams (0.64 mole) bottle, a bubbler containing concenof 2-methyl-3,3-dichloro-l,l ,I-trifluorotrated sulfuric acid, and another safety 2-propanol there was obtained 47 grams bottle. An 8-watt germicidal ultra(0.29 mole, 4670 yield) of epoxide. violet bulb was used for catalytic illumi2-Methyl-3-bromo- i,i,1-trifluoro- 2nation. propanol (78). Methylmagnmium broA solution containing 110 ml. of 2mide (2.0 moles in 1200 ml. of ether) was methyi 1,1,1 trifluoro - 2 - propanol prepared in the usual way and added to (128 grams, 1.0 mole) and 220 ml. of 3 bromo - 1,1,1 trifluoroacetone (191 carbon tetrachloride (395 grams, 2.24 grams, 1.0 mole) over a 3-hour period. moles) was placed in the reactor and After standing several hours, the excess heated to 65' C. The chlorine (65 Grignard reagent was destroyed with grams, 0.915 mole) was weighed into water and the complex was hydrolyzed a cold trap, then connected to the feed by the addition of 500 ml. of ice-cold system. The rate of chlorine addition 4070 sulfuric acid solution. The organic was controlled by partially withdrawing layer was separated and dried over this trap from a Dewar flask. The Drierite; then the ether was removed by chlorine was added during a 7-hour distillation. Rectification of the residue period and the reaction temperature 3,3,4,4,5,5,5-Heptafluoro-2-pentanol. through a Todd column (12-mm. barwas maintained between 60' and 75' C. 2,2,3,3,4,4,4 Heptafluorobutyraldehyde rel packed with '/,-inch glass helices) Initially the reaction mixture remained (74, 22) (271 grams, 1.37 moles) was yielded 69 grams (0.33 mole, 33% yield) colorless, but it slowly developed a added to an ethereal solution of methyl of 3-brom0-2-methyl-1,l ,I-trifluoro-2green color. magnesium bromide (prepared in the propanol, boiling point 122-5' C., n g After the chlorine addition was comusual way from 2 gram atoms of magne1.3981. The product had a brown color, pleted, a stream of dry nitrogen was sium), After hydrolysis, drying-, and apparently caused by decomposition passed through the solution for 6 hours. rectification there wasobtained 153 grams within the column. The product was fractionated through (0.72 mole, 53% yield) of heptafluoro-2a Todd column (1 2-mm. barrel, packed pentanol, boiling point 101-2' C. 2-Methyl-3,3,3-trifluoro-1,2epoxywith '/*-inch glass helices). There was This alcohol was also prepared by the propane was prepared in the same manobtained 46 grams (0.283 mole, 28.3%) 2-methyl-3-chloro-l,l,l-trifluoro-2- ner as 3,3,3-trifluoro-1,2-epoxypropane. reaction of methyl heptafluorobutyrate of with a mixture of methyl and isopropyl. From 164 grams (1.0 mole) of 2-methylpropanol. magnesium halides (25). 3-chloro-1 , I , 1 -trifluoro-2-propanol there Procedure B. Using the same prowas obtained 98 grams (0.78 mole, 78% cedure, but with no solvent (which peryield) of 2-methyl-3,3,3-trifluoro-1,2- 2-MethyI-3,3,3-trifluoropropene and mits higher reaction temperature) and 3,3,4,4,5,5,5 Heptafluoro 1 pentene epoxypropane. an improved ultraviolet light source The use of 3-bromo-2-methy1-1,1,1were prepared by dehydration with phos(G.E. "Black Light," 8 watts) maximum trifluoro-2-propanol gave the same yield phorus pentoxide of 2-methyl-3,3,3chlorination yields of 5670 have been trifluoro-2-propanol and 3,3,4,4,5,5,5of epoxide. obtained. heptafluoro-2-pentanol, respectively (72, 2-Chloro-2,2-difluoroethanol a n d 2,224). 2-Methyl-3,3-dichloro-l,l,l-trifluoro- Dichloro-2-fluoroethanol. Chlorodi2-propanol was obtained by rectification fluoro- and dichlorofluoroacetic acids Hypochlorination Studies of the combined higher boiling portions were obtained from the General Chemfrom several preparations of the monoical Division and converted to the acid Kadesch's procedure (75),in which chloro alcohol. chlorides by heating with benzoyl an olefin and carbon dioxide gas are chloride ( 2 ) . The crude acid chlorides added simultaneously to an aqueous soluwere reduced with lithium aluminum tion of calcium hypochlorite, failed to 1-Chloro 2 methyl-3,3,3-trifluorohydride to yield 2-chloro-2,2-difluoroyield a chlorohydrin with vinylidene 1,2-epoxypropane was prepared in the fluoride, 2-methyl-3,3,3-trifluoroprosame manner as 3,3,3-trifluoro-1,2-epoxy- ethanol, boiling point 95-6' C., n g
-
-
-
-
-
-
-
- -
Table II.
Oxide, g. FeC13, g. FeCls, 70 Time, hr. Polymer, g. %conversion
1244
Polymerization of 3,3,3-Trifluoro-1,2-epoxypropane
1
2
3
4
12.0 0.1 0.8 41.0 1.0 8.3
12,O 0.2 1.6 41.0 2.5 20.8
18.5 0.45 2.4 48.0 14.0 76.7
19.0 0.45 2.4 48.0 13.0 68.4
(Ferric chloride catalyst at 90° t o 100' C.) 5 6 7 8 9
INDUSTRIAL AND ENGINEERING CHEMISTRY
18.5 0.45 2.4 48.0 13.0 70.3
12.0 0.1 0.8 64.0 5.0 41.6
12.0 0.2 1.6 64.0 4.5 37.5
19.0 0.45 2.4 64.0 15.5 81.6
19.0 0.45 2.4 64.0 15.5 81.6
10 18.5 0.45 2.5 64.0 14.5 78.3
11
12
13
14
15
18.0 0.60 3.3 64.0 15.5 86.2
19.0
19.0 0.60 3.2 64.0 15.5 81.6
12.0
12.0 0.2 1.6 72.0 5.0 41.6
0.6 3.2 64.0 15.0
78.9
0.1
0.8 72.0 3.0 25.0
FLUORINE-CONTAINING POLYETHERS pene, or 3,3,4,4,5,5,5-heptafluoro-l-pentene. The method described by Coleman and Johnstone (6) was applied to 2methyl-3,3,3-trifluoropropeneand 3,3,44,5,5,5-heptafluoro-l-pentene. 2 - Methyl - 3,3,3 trifluoropropene was chilled and treated with six 250gram portions of 2y0 hypochlorous acid solution during a 30-hour period, each portion being added after a negative test for hypochlorous acid had been obtained from the preceding portion. Sixteen hours after addition of the sixth portion a positive test for hypochlorous acid was obtained, indicating complete reaction. The reaction mixture was extracted with ether, and the ethereal solution dried over Drierite. After removal of the ether by distillation, the residue was distilled through a Podbielniak Mini-Cal column (concentric tube barrel). A material was obtained (boiling point 112' C., melting point ca. 20' C.) which solidified on the condenser. A similar reaction was conducted and the product was combined with the solid product from the first run. This material was fractionated through a Podbielniak Mini-Cal column; the product cut (boiling point 116' C.) had a melting point of 41-8' C. This cut was again fractionated through the same column to obtain a smaller portion (center cut, melting point 45' C.) of material. This material when treated with a hot solution of 5OOj, aqueous sodium hydroxide yielded a volatile product which was shown by infrared analysis to contain 2-methyl-3,3,3-trifluoro-l,2epoxypropane. Thus it was indicated that some hypochlorous acid had been added to the olefin. The same procedure was without effect when applied to 3,3,4,4,5,5,5-heptafluoro-1-pentene.
-
drical steel safety tube and mounted on a motor-driven wheel which revolved within a Transite-lined box. The box was heated by thermostatically controlled electric heaters. Even distribution of heat was effected by a fan mounted in the box. The fan motor and sample wheel motor were mounted outside the box.
Procedure. The clean bottle was flushed with dry nitrogen and weighed with its cap, which was fitted with a Teflon liner (0.003 inch thick) to prevent erosion of the cork. Catalyst was weighed into a dry test tube, then charged to the bottle. The oxide was then pipetted into the bottle, which was capped, weighed, placed in the constant temperature air bath, and tumbled for a desired time at a preset temperature. The bottle was then removed from the apparatus and weighed to determine any loss incurred through leakage. Unused monomer was removed by applying vacuum from a water aspirator, a cold trap being interposed between the flask and pump to collect the oxide for subsequent purification and re-use. The bottle with its contents and cap was weighed once again. Conversions were calculated by dividing the weight of the polymer obtained by the weight of monomer charged. Catalysts. Fisher's C.P. anhydrous ferric chloride, Baker's C.P. aluminum chloride, sulfur trioxide in the form of Sulfan B (General Chemical Division), and Matheson Co. boron trichloride were employed as catalysts.
Polymer Purification. Procedure 1. The polymer was dissolved in an excess of hot acetone acidified with 1 ml. of concentrated hydrochloric acid per 100 ml. of acetone. The resulting solution Peracid Oxidation Studies was concentrated to a small volume by evaporation, then chilled and diluted When 2-methyl-3,3,3-trifluoropro- to 8 or 10 times its volume with water. pene was treated with a benzene soluThe solid polymer thus obtained was tion of perbenzoic acid (7) at 0' C. for filtered and dried in a vacuum oven 24 hours no reaction occurred. As the for several hours at 100' C. If the polytemperature was increased gradually, mer was colored, the procedure was rethe perbenzoic acid decomposed slowly, peated, although the use of hydrochloric but no oxidation of the olefin was effected. acid in the acetone was unnecessary. Application of the method described Procedure 2. The polymer was disby Emmons and Pogano (8)for the oxidasolved in an excess of hot acetone acidition of olefins with peroxytrifluoroacetic fied with 1 ml. of concentrated hydroacid likewise failed with 2-methyl-3,3,3chloric acid per 100 ml. of acetone. The trifluoropropene. resulting solution was saturated with anhydrous ammonia to precipitate iron salts. The precipitate was filtered and Epoxide Polymerizations washed with hot acetone several times. Apparatus. All polymerizations were The filtrate and washings were concenconducted in ordinary Coke bottles, trated to a small volume by evaporation, carefully cleaned and dried before use. and treated as in Procedure 1. This These bottles were placed inside a cylinprocedure was satisfactory with liquid
polymers, or where only small amounts of solid polymer were involved, but it was cumbersome for more than about 16 grams of solid polymer. The acetone solutions become too viscous in any reasonable concentration to permit easy filtration from the inorganic salts.
Experimental Data. Composite data for tests made at 80' to 100" C. for 24 hours are shown graphically for two epoxides in the figure. 3,3,3, Trifluoro - 1,2 - epoxypropane formed a solid polymer with ferric chloride catalysis. Typical experimental results are shown in Table 11, from which it can be seen that optimum conversion conditions are 2 to 391, of ferric chloride a t 90' to 100' C. for 64 hours. Equally high conversions can be obtained by the use of higher catalyst concentrations over a 24-hour period, but the polymers obtained under those conditions do not have the toughness, and they are waxier than those produced under optimum conditions. A sample of polymer prepared according to the above optimum conditions had a weight-average molecular weight of 230,000 by a light-scattering procedure. This material was thermally stable, and insoluble in chlorofonn, carbon tetrachloride, methylene dichloride, benzene, toluene, and trichloroethylene.
-
3,3,3-Trifluoro-1,2-epoxypropane with aluminum chloride formed a viscous, fluid polymer. The rate of polymerization was faster, lower temperatures could be used, and all monomer was converted to polymer. No solid polymer was formed. 2-Methyl-3,3,3-trifluoro-1,2-epoxypropane and l-chloro-2-methyl-3,3,3trifluoro-l,2-epoxypropaneformed liquid polymers regardless of the catalyst used. With the latter epoxide, conversions were very low. The results of copolymerization studies are shown in Table 111. The only catalyst studied was ferric chloride. The polymers became increasingly tacky ap the per cent of 2-methyl-3,3,3-trifluoro1,2-epoxypropane was increased. A small sample of 3,3,3-trifluoro-1,2epoxypropane was submitted to cobalt-60 No polymerization had radiation. occurred after 16.2-mrep. exposure. Small samples of 3,3,3-trifluoro-1,2epoxypropane were treated with catalytic amounts of tert-butyl hydroperoxide and benzoyl peroxide. No polymerization had occurred after 72 hours a t 90 O to 100" c. Attempts to Increase Molecular Weight
Liquid 3,3,3-Trifluoro-i,Z-epoxypropane Polymer. The polymer and VOL. 49, NO. 8 'e
AUGUST 1957
1245
Table 111.
7 7 7 1 Copolymerization of CF3CHCHsO with CF3C(CHJCH20
(1) Braun, G., “Organii Synthcsih,’ Coll
(FeCIa catalyst, 80-90O C., 24 hours)
m
7
1
CFaCHCHpO, CFaC(CH3)CH20, Val. % Vol. %
5
95
Combined Oxides, G.
FeCla,
Polymer,
Wt. yo
G.
Conversion, %
12.5
5
8.5
68
9s
5
12.5
5
9.5
76
90
10
12.5
5
8.5
68
90
10
12.5
5
8.5
68
80
20
13.0
5
9.0
69
80
20
13.0
5
9.5
73
..
5
..
905
6
*.
95“
50
50
50
50
1.
‘Recovered monomer mixture had nag 1.3052. reagent were mixed with catalyst (if used), sealed in a glass ampoule, and heated in a n oven a t 110’ C. for varying lengths of time. Whether or not reaction had occurred was determined visually by comparing the viscosities of the treated polymers with an untreated sample. When maleic anhydride was employed (2 grams of pol>mer, 0.2 gram of anhydride) with p-toluenesulfonic acid (0.02 gram) as catalyst, no change in viscosity of the ffuid was observed after overnight heating. The maleic anhydride remained undissolved in the liquid. When hexamethylene diisocyanate (2 grams of polymer, 0.2 gram of diisocyanate) was used with pyridine (0.02 gram), the viscosity of the polymer had increased noticeably after overnight heating, and some solid material had formed. There was not sufficient solid material present to permit its characterization. In all probability, the molecular weight of rhe polymer was increased by diisocyanate.
-
2 -Methyl-3,3,3 trifluoro- 1,2-epoxypropane Polymers. Three 1-gram samples of the polymer were mixed with 0.05, 0.1-, and 0.2-gram portions of hexamethylene diisocyanate in small glass ampoules. A fourth ampoule was loaded with the polymer and no diisocyanate. The ampoules were sealed and placed in a 150 ’ C. oven for 24 hours. After this reaction period the samples were cooled. A definite change could be noted in every sample containing the diisocyanate. The polymer sample containing no reagent did not appear to be changed, but the sample containing 5% diisocyanate was a brown, highly viscous liquid. The samples containing 1Oyo and 20% reagent were darker brown and more viscous than initially, although not so viscous as the sample containing 570 reagent. Possibly all polymers were of equally high molecular
1 246
In all other cases n g
< 1.3.
weight, but dilution with the diisocyanate lowered the apparent viscosity. Polyglycol Formals
Procedure .4. An attempt was made of 2,2,3,3,4,4-hexafluoro-1,5-pentanedioI (79, 23) with butyl formal (29) exactly as described by Hill and Carrothers (73), who employed the non-fluorine-containing analogs. Butyl formal and 570 excess glycol, with a catalytic amount of anhydrous ferric chloride. were heated together ar atmospheric pressure, then under reduced pressure. While some reaction occurred: as evidenced by the production of impure butanol, the results were inconclusive. .4 large amount of charring occurred, and most of the glycol was recovered unchanged. Procedure €3. Procedure A was repeated, but p-toluenesulfonic acid was used as the catalyst. After heating under vacuum (25 mm. of mercury) for 24 hours, the reaction mixture was dissolved in hot benzene. Cooling this benzene solution precipitated unreacted glycol (50’%). When the benzene was evaporated in a stream of air, a liquid residue remained, Heating the residue on a steam bath caused the evolution of formaldehyde, and additional glycol was precipitated. Upon prolonged standing, more glycol was precipitated. I t seems likely that unstable glycol formal (eirher linear, or a cyclic monomer or dimer) was formed, which easily depolymerizes on standing or heating. to cause reaction
Acknowledgment
T h e authors wish to thank 0. K. Johannson and G. F. Pollnow for measuring molecular weights, R. J. Koch for conducting vulcanization studies, and W. C. Ragborg for lubrication tests. Bruce Wilkinson and F. W. McLafferty, Dow Chemical Co., conducted reactions involving cobalt-60 and mass spectrographic analyses.
INDUSTRIAL A N D ENGINEERING CHEMISTRY
Literature Cifed Vol. 1, 2nd ed., p. 431, Wiley, New York, 1941. (2) Brown, H. C., J . Am. Chem. Sac. 60, 1325 (1938). ( 3 ) Chaney, D. W. (to American Viscose
Corp.), U . S. Patent 2,439,505 (1 948). (4) Pbrd., 2,456,768 (1948). (5) Ibtd., 2,514,473 (1 950). ( 6 ) Coleman, G. H., Johnstone, H F., “Organic Synthesis,” Coll. Vol. 1, 2nd ed., p. 158, Wiley, New York, 1941. (7) Dickey, J. B., Towne. E. B. (to Eastman Kodak Co.), TJ. S. Patent 2,700,686 (1955). (8) Emmons. W. D., Pogano, A. S., J . Am. Chem. SOC. 77, 89 (1955). (9) Cryszkiewicz-Trochimoski, E., others, Rec. trav. chim. 66, 413 (1947). (10) Guss, C. O., Rosenthal, R., J. Am. Chem. SOC. 77, 2549 ( 1 955). (11) Hauptschein, M., Lesser, J. M., Ibid., 78, 676 (1956). (12) Henne, A. L., Shepard, J . W.. Young, E. J., Ibid.,72, 3577 (1950). (13) Hill, J. W., Carrothers, W. H., Ibid., 57, 925 (1935). (14) Husted, D. R., Ahlbrecht. .I H., Ibid., 74, 5422 (1952). (15) Kadesch, R . C.,Zbid., 68, 41 11946). (16) Knunvants, I L., otherr, J . Gel. C h m . ( U S.S.R.) 19, 95 (1942). (17) McBee, E. T., Burton, T. M., .I. Am. Chem. Soc. 74, 3022 (1952). (18) McBee, E. T., Hathaway, C. E , Roberts, C. W., Ibid., 78, 40.53 (1 956 ). (1 9 ) McBee, E. T., Marzluff, W. F., Pierce. 0. R., Zbid., 74, 444 (1952). (20) McBee, E. T., Pierce, 0. R., Kilbourne, H. W., [bid., 75, 4091 11953). (21) McBee, E. ‘T., Fierce, 0 . K.,Marzluff, W. F., Ibid., 75, 1609 (1953). (22) McBee, E. T., Pierce, 0 . R., Smith, D. D., Ibid., 76, 3722 (1954). (23) McBee, E. T., Wiseman, P. A,, Bachman, G. B., IND.ENG. CHEM.39, 415 (1947). (24) Pierce, 0. R., McRee, E. T., Cline, R. E.. J . Am. Chem. Sac. 75, 5618 (1953). (25) Pierce, 0. R., Siegle. J. C., McRee, E;. T., Ibid., 75, 6324 (1953). (26)’ Simons. J. H, (to Minnesota Mining and klfg. Co.’), U. S. Patent 2,519,‘: 983 (1950). (27) Swarts, F., Bull. acad. roy. Relg. 13, 191 (1 927). (28) Swern, D., “Organic Reactions,” vol. VII, p. 378, Wiley, New York, 1953. (29) Vogel, A. I., J . Chem. SOC. 1948, 616. (30) Whaley, A. M., U. S. Patent 2,451,185 (1948).
RECEIVED for review November 16, 1956 ACCEPTED January 31, 195’ Divisions of Polymer and Industrial and Engineering Chemistry, Fluorine Chemistry Subdivision, Symposium on FluorineContaining Polymers, 130th Meeting. ACS, Atlantic City, N. J., September 1956. Work performed under Contract No. AF 33(616)-2417, Materials Laboratory, Wright Air Development Center, Wright-Patterson Air Force Base, Ohio.
