Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
TITLE
FLUORINATED POLYETHER
AND DERIVATIVES THEREOF
Description
Technical Field
Thic invention relates to perfluoro[~-(1,2-
dihalotrifluoroethoxy)carboxylates], to functionally-
substituted polyethers produced therefrom, including
fluorinated slefins, and to polymers of the fluori-
nated olefins.
Backqround Art
United States Patents 4,131,740 and 4,138,426disclose fluorinated compounds, including olefins of
the formula YCF2CF2O[CF(CF3)CF2O]pCF=CF2 wherein p is
0 to 5 and Y is cyano or carboxyl, or ester or alkali
metal, ammonium or quaternary ammonium salt thereof.
Similar compounds wherein, using the aforesaid
formula, Y is chloro, bromo or iodo, are known from
United States Patents 3,351,619 and 4,275,226. The
olefins of the aforesaid formula generally can be
prepared by pyrolyzing the corresponding acid
fluoride over a basic salt.
The addition of chlorine, bromine or alcohols
to fluoroolefins is known, for example, from Fainberg
and Miller, J. Am. Chem. Soc., 79, 4170 (1957);
"Chemistry of Organic Fluorine Compoundsn, Hudlicky,
The ~acMillan Company, New York, 1962, page 247, 248;
and ~Chemistry of Organic Fluorine Compoundsn, 2nd
(Revised) edition, Hudlicky, Ellis Horwood Lt~.,
Chichester, England, 1976, pages 214-216. The conver-
sion of perfluorinated aliphatic monocarboxylic acids
and salts thereof to aliphatic chlorides, bromides
and iodides is known, for example, from United States
Patent 2,647,933: Hudlicky, supra, 1962, page 226;
CR-8056 1 35 and Haszeldine, J. Chem. Soc., 1951, 584.
~ 3
It is an object of this invention to provide
chlorodifluorovinyloxyperfluoroalkyleneoxyalkyl tri-
fluoromethyl ketones and acyl fluorides; chlorodi-
fluorovinyloxyperfluoroalkyleneoxyethylenes; substi-
tuted fluoroalkoxyperfluoroalkyleneoxyalkyl trifluoro-
methyl ketones and acyl fluorides; substituted fluoro-
alkoxyperfluoroalkyleneoxyethylenes; processes for
their preparation and for the preparation of per-
fluorovinyloxyalkyleneoxyalkyl bromides; and
copolymers of derivatives of the aforesaid vinyl
compounds. Other objects will become apparent
hereinafter.
Disclosure of Invention
For further comprehension of the invention,
and of the objects and advantages thereof, reference
may be made to the following description and to the
appended claims in which the various novel features
of the invention are more particularly set forth.
The invention herein resides in processes
for preparing fluorinated compounds, and more speci-
fically, fluorinated compounds which are of the
formulas:
~1) CF2=CFO[CF2CF(CF3)O]nCF2CF2Br;
(2) (-F2XCFXlO[CF2CF(CF3)O]n_lcF2c(O)cF3;
(3) CFCl=CFO[CF2CF(CF3)O]n_lCF2C(O)CF3;
(4) ~2o[cF2cF(cF3)o]nlcF(cF3)cF2o]p ~
CF(CF3)COF; and
(5) S~O[CF2CF(CF3)O]n[CF(CF3)CF2O]pCF=CF2
wherein n is an integer and is 1 to 6, p is an
integer and is 0 to 3, Q is CF2XCFXl or CFCl=CF,
X and X are both Cl or X is F or OR and Xl is H,
and R is methyl, cyclohexyl, phenyl or alkyl of 2 to
~ 3 ~
6 carbon atoms optionally interrupted with ether
oxygen.
The invention herein also resides in the
fluorinated compounds of formulas 2 to 5, preferred
embodiments of which include those wherein, in
formulas 2 to 5, n is 1; in formula 2, X and Xl are
both Cl or X is OCH3 and Xl is H; and in formulas
4 and 5, p is 0 and X and X are both Cl or ~ is
OCH3 and Xl is H.
In summary of the processes of the inven-
tion, the compound of formula 1 is obtained by
pyrolyzing the salt of the formula
(6) CF2x2cFx3o[cF2cF(CF3)o]ncF2cF2co2M(l/m)
wherein M is an alkali or alkaline earth metal of
valence m and x2 and X3 are both Br; the compound
of formula 2 is obtained by pyrolyzing the compound
of formula 6 wherein M is as previously defined, x2
and X3 are both Cl, or x2 is F or OR, as previ-
ously defined, and X3 is H. The compound offormula 3 is obtained by heating the compound of
formula 2, wherein X and Xl are both Cl, with
magnesium or a mixture of zinc and zinc chloride.
The compound of formula 4 is obtained by reacting
either of the compounds of formulas 2 and 3 with
hexafluoropropene oxide (HFPO); the compound of
formula 5 is obtained by pyrolysis of the compound of
formula 4.
The precursor of the salt of formula 6 is
prepared by reacting the known ester of the formula
CF2=CFOlCF2CF(CF3)O]nCF2CF2CO2R ,
wherein n is an integer and is 1 to 6 and Rl is
methyl or ethyl, with bromine, chlorine, hydrogen
fluoride or an alkanol of the formula ROH wherein R
is as defined above. Use of an aprotic solvent, such
~ 3 ~
as tetraglyme, although not essential, may be desir-
able, particularly as the value of n increases. The
reaction with bromine or chlorine is facilitated by
cooling the reaction flask in ice and irradiating
with W light. The reaction with the alkanol of the
formula ROH is carried out in the presence of a small
amount of an alkoxiae RO~' wherein R is as defined
above and M' is an alkali metal cation. Methyl
alcohol and ethyl alcohol are the preferred alcohols.
An excess of alcohol is nomally preferred. The addi-
tion of hydrogen fluoride across the double bond does
not proceed readily, but may be accomplished by nucle-
ophilic addition of fluoride ion by means of an
alkali metal fluoride such as potassium fluoride in a
proton-donating liquid such as formamide.
After the addition across the double bond of
the ester has been completed, the resultant ester is
converted to the alkali metal or akaline earth metal
salt of formula 6 by hydrolyzing with an alkali or
alkaline earth metal hydroxide, preferably sodium
hydroxide or potassium hydroxide, dissolved in water
or, preferably, in methyl alcohol. Alternatively,
the salt of formula 6 wherein x2 is OR and X3 is
H can be prepared in one step from the aforesaid
unsaturated ester by reaction with an alkanol R~,
wherein R is as defined above, in the presence of an
alkali metal hydroxide, such as sodium hydroxide or
potassiu~ hydroxide, the hydroxide being present in
slight mclar excess ~ith respect to the ester.
The salt, of formula 6, is isolated and
pyrolyzed in a suitable aprotic solvent, such as a
glyme ~mono-, di-, tri or tetraethyleneglycol dimethyl
ether), preferably tetraglyme, at a temperature of
about 130C to about 300~C, preferably 170C to
230C. Preferably, the solvent should be higher
boiling than the pyrolysis reaction product, the
compound of either formula 1 or formula 2.
Alternatively, although less desirably, the
unhydrolyzed halogenated or alkanolated ester can be
pyrolyzed in a suitable aprotic solvent, at the
aforesaid temperatures, in the presence of a carbon-
ate, phosphate, sulfite or sulfate salt of an alkali
or alkaline earth metal, preferably sodium carbonate,
trisodium phosphate or sodium sulfite, said unhydro-
lyzed halogenated or alkanolated ester being of theformula
CF2X2CFX30tCF2CF(CF3)O]nCF2CF2C02Rl
wherein n is an integer and is 1 to 6, Rl is methyl
or ethyl and x2 and X3 are both Br or Cl or x2 is OR
wherein R is methyl, cyclohexyl, phenyl or alkyl or~i2
to 6 carbon atoms optionally interrupted with e.her
metal salts (catalysts) are not required or desirable
when the alkali or alkaline earth metal salt of
formula 6 is pyrolyzed.
I~ is important that all reactants and
solvents used in the pyrolysis of the alkali or
alkaline earth metal salt of formula 6 be moisture-
free. The presence of water or other proton-bearing
compounds during pyrolysis lowers the yield of the
desired bromide of formula 1 or ketone of formula 2
by producing a hydrogen-capped by-product of the
formula
CF2X2CFX30[CF2CF(CF3)0]nCF2CF
wherein n, x2 and X3 are as defined above.
Various methods of drying the alkali or
alkaline earth metal salt of formula 6 can be used,
including evaporative removal of water, azeotropic
distillation of water with toluene, and neutraliz-
ation in methanol solution followed by evaporative
removal of methanol. In all these methods final
drying in a vacuum oven is required to ensure com-
plete removal of water or methanol. Neutralizationin methanol is preferred because less foam is gener-
ated in the drying process, and the lower boiling
point and lower heat of vaporization of methanol
relative to water increases the drying rate.
Solvents used in the pyrolysis of the salt
are dried by standard methods for drying organic
liquids; distillation from sodium hydride is
convenient.
As indicated above, the salt of formula 6 is
an alkali or alkaline earth metal salt. Ammonium or
tetraalkylammonium salts should be avoided, since
their pyrolysis also leads to the formation of
hydrogen-capped products or to the formation of alkyl
esters.
Reaction pressure is not a critical variable
for the pyrolysis of the salt of formula 6. Pressure
above or below atmospheric pressure can be employed.
Atmospheric or subatmospheric pressure is preferred,
however, because of the comparative ease of recover-
ing the distillable reaction products.
~ rhe pyrolysis of the salt of formula 6
wherein X and X are Br provides the bromo-
functional perfluorovinyl ether of formula 1, along
with a by product of the formula
CF2BrCFBrO[CF2CF(CF3)OlnCF2CF2Br wherein
n is as defined above, shown in Example 4. The by-
product can be converted to the vinyl ether of
formula 1 by heating in the presence of metallic zinc
or magnesium, which selectively eliminates bromine
from the 1,2-positions. Such an elimination of
bromine from fluorinated 1,2-dibromoalkanes is known,
for example, from Hudlicky, supra, 2nd (Revised)
edition, pages 482, 483.
The formation of the vinyl ether of formula
5 1 by pyrolysis of the dibrominated salt of formula 6
is not only novel but unexpected. Pyrolysis of the
dichlorinated salt of formula 6, under similar condi-
tions, does not yield the chloride analog of formula
1, but rather the 1,2-dichloro- trifluoromethyl
ketone of formula 2. Pyrolysis of the alkanolated
salt of formula 6 also yields a trifluoromethyl
ketone of formula 2 wherein X is OR and Xl is H.
The vinyl ether of formula 1 can be copoly-
merized with fluorinated olefins, for example, tetra-
fluoroethylene, chlorotrifluoroethylene, vinylidenefluoride and perfluoroalkylvinyl ethers wherein the
alkyl moiety contains 1 to 4 carbon atoms. The
resulting copolymers, which contain pendant bromo
groups, are curable to fluoroelastomers by means of
peroxides and heat or by means of W radiation.
Formation of the trifluoromethyl ketone of
formula 2 by pyrolysis of the salt of formula 6,
wherein x2 and X3 are Cl or x2 is F or OR and
X3 is H, is accompanied by the loss of one mole of
tetrafluoroethylene, one mole of carbon dioxide and
one mole of sodium fluoride per mole of salt.
The trifluoromethyl ketone of formula 2
wherein X and X are both Cl can be dechlorinated
to the monochlorodifluorovinyl ether of formula 3 by
heating in the presence of magnesium or a mixture of
zinc and zinc chloride in an aprotic solvent such as
diglyme.
The ketone of formula 2 where X and X are
both Cl or X is F or OR and X is H, and the vinyl
9~
ether of formula 3, can be reacted with hexafluoro-
propene oxide (such as in Example 10) and the result-
ant adduct, of formula 4, can be pyrolyzed in the
presence of a carbonate, phosphate, sulfite or sul-
5 fate salt of an alkali or alkaline earth metal, pre-
ferably sodium carbonate, trisodium phosphate or
sodium sulfite, or after conversion to a salt by
alkaline hydrolysis, to the copolymerizable vinyl
ether monomer, of formula 5, by known methods, such
10 as those disclosed in United States Patent 3,274,239.
The vinyl ether 5 can be copolymerized with fluorin-
ated olefins such as, for example, tetrafluoroethy-
lene, chlorotrifluoroethylene, vinylidene fluoride,
and/or perfluoroalkylvinyl ethers wherein the alkyl
15 moiety contains 1 to 4 carbon atoms, the fluorinated
copolymers being moldable into shaped articles.
Copolymers prepared from the monomer of
formula 5 wherein Q is CF2XCFX , X is OR and X
is H can be further reacted by known methods to con-
vert the pendant RO- group to another useful
functional group, for example, an ester (RO2C-) or
acyl fluoride (FOC-) group. Copolymers containing
these groups are, after hydrolysis, water-wettable
and dyeable and possess ion-exchange properties. The
formation of the ester can be carried out in 96%
sulfuric acid at 0C to 10C by the process of
Hudlicky, supra, 2nd (Revised) edition, page 271.
The formation of the acyl fluoride can be carried out
by reaction of the vinyl ether monomer or a copolymer
thereof with a selected metal halide, such as
antimony pentafluoride.
Copolymers prepared from the monomer of
formula 5 wherein Q is CFCl=CF retain this terminal
vinyl group and can be thermally cured to useful
elastomers.
The ketone of formula 2 also can be reacted,
under basic conditions, optionally in the presence of
a solvent, with glycol half-esters to form 1,3-
dioxolanes by known methods, such as disclosed in
5 United States Patent 2,925,424. By methods s~ch as
disclosed in United States Patents 3,865,845 and
3,978,030, 1,3-dioxolanes can be converted to poly-
merizable fluorinated dioxoles.
In the following experiments and examples,
10 parts are by weight unless otherwise indicated.
Experiments 1 and 2 are representative of procedures
for the preparation of intermediates, Examples 1 to 7
are representative of the invention.
EXPERIMENT 1
A. A 300 mL, 3-neck round-bottom flask
fitted with a magnetic stirrer, pressure-equalizing
dropping funnel and air-cooled condenser topped by a
nitrogen bubbler, was flushed with nitrogen and
charged with 117.5 9 (0.28 mol) of methyl perfluoro-
4,7-dioxa-5-methyl-8-nonenoate. Bromine was added
with stirring and the reactant mixture was irradiated
with a General Electric* sunlamp. Bromine uptake wa~
rapid. When a slight molar excess of bromine had
been added, the flask was cooled in ice water.
Excess bro~mine was destroyed by adding 20~ aqueous
sodium bisulfite solution. Two liquid layers were
obtained. The lower layer was separated and washed
with cold water; yield of crude product was 157.5 g.
Distillation provided 147.3 9 (91.0% yield) of color-
less product; boiling point 86-88~C/9 mmi Analyses
using gas chromatography, infrared and F NMR
procedures confirmed that the product was methyl
8,9-dibromo-perfluoro-4,7-dioxa-5-methylnonanoate,
cF2BrcFBrocF2cF(cF3)ocF2cF2co2cfi3-
* denotes trade mark
B. 58.2 9 of the ester prepared as in PartA, 50 mL of water and 4.0 9 of sodium hydroxide were
stirred at room temperature for 3 h in a 200 mL flask
fitted with a magnetic stirrer and air-cooled con-
5 denser under nitroqen. The single liquid phase whichwas obtained was evaporated to dryness; yield of
product was 54.8 9 (92.9%). The F NMR analysis
of an aqueous solution of the product showed it to be
sodium 8,9-dibromo-perfluoro-4,7-dioxa-5-
10 methylnonanoate, CF2BrCFBrOCF2CF(CF3)OCF2CF2CO2Na,that is, the compound of formula 6 wherein X and
X are both Br and n is one.
EXPERIMENT 2
A. A 200 mL flask fitted as described in
15 Experiment lA, except that the condenser was replaced
by a Dry Ice-cooled trap, was charged with 77.9 g of
methyl 4,7-dioxa-perfluoro-5-methyl-8-nonenoate and
100 mL of 1,1,2-trichloro-1,2,2-trifluoroethane. The
flask was cooled in an ice bath, irradiated with a
General Electric sunlamp, and chlorine was added. The
reaction was exothermic and gas was evolved. Chlorine
addition and irradiation were continued until gas evo-
lution ceased. The reaction mixture, cooled in an ice
bath, was treated with 75 mL of methanol, followed by
1.6 L of ice water. The lower layer which separated
was removed and washed well with ice water. Fraction-
al distillation of the lower layer resulted in 62.9 g
(90.5~ yield) of product, boiling point 77-78C/10 mm.
Analyses by gas chromatography, infrared and 9F
NMR confirmed that the product was methyl
8,9-dichloro-perfluoro-4,7-dioxa-5-methylnonanoate),
CF2ClCFClOCF2CF(CF3)OCF2CF2CO2CH3.
B. 19.5 9 of the ester product of Part A was
hydrolyzed in 40 9 of 50% aqueous sodium hydroxide and
40 9 of water as described in Experiment lB to obtain
a~ 3
sodium 8,9-dichloroperfluoro-4,7-dioxa-5-methylnon-
anoate, CF2ClCFClOCF2CF~CF3)OCF2CF2CO2Na, that is,
the compound of formula 6 wherein x2 and X3 are
both Cl and n is one.
EXAMPLE 1
Fifty grams of methyl perfluoro(4,7-dioxa-5-
methyl-8-nonenoate), CF2=CFOCF2CF(CF3)OCF2CF2CO2CH3,
was slowly added to a flask containing 50 mL of me.hy-
anol and 4.8 g of sodium hydroxide. I~hen the addition
was complete, stirring was continued for 2 h. The
excess methanol was evaporated and the semi-dry solid
sodium salt was placed in a vacuum oven overnight.
Forty-six grams of the dried salt was added
to a dry nitrogen-flushed flask along with 125 mL of
tetraglyme. The mixture was warmed at a rate of about
5C~min. At 195C decomposition of the salt began
and product was distilled from the reaction mixture as
it formed. Heating was continued to 205C for 10 min,
at which time the decomposition was complete. The
crude product was distilled to yield 6.1 g of pure
material which was identified by its fluorine and
proton nuclear magnetic resonance spectra, its infra-
red spectrum and its high resolution mass spectrum,
all of which were consistent with the compound
25 1,1,1,3,3,5,6,6-octafluoro-5-~-2-oxo-4,7-dioxaoctane,
CH3OCF2CFHOCF2C(O)CF3, that is, .he compound
of formula 2 wherein X is methoxy, Xl is hydrogen
and n is one.
EXAMPLE 2
Fifty grams of methyl perfluoro(4,7-dioxa-
5-methyl-8-nonenoate) was placed in a flask and
cooled to 0C. Nineteen grams of bromine was added
dropwise with stirring. The mixture was allowed to
stir overnight and was then extracted with water,
treated with activated carbon and filtered to yield a
12
light orange liquid. The dibromide product, 59.2 9,
was cooled in ice water and 4.07 9 of sodium hydroxide
dissolved in 25 mL of water was added dropwise. When
all the sodium hydroxide was added, two layers formed.
The mixture was shaken to yield a clear solution of
neutral pH. The water was evaporated and the
resultant salt was dried in a vacuum oven at 100C.
The salt was pyrolyzed in tetraglyme as described in
Example 3. The crude product was distilled to yield
17.4 9 of pure product which was identified from its
fluorine nuclear magnetic resonance spectrum and its
high resolution mass spectrum and shown to be
8-bromo-perfluoro-3,6-dioxa-5-methyl-1-octene,
CF2=cFocF2cF(cF3)ocF2cF2Br~ that is, the
compound of formula 1 wherein n is one.
The reaction was repeated as described
above, but at a two-fold increase in scale. In this
case 35.5 9 of the bromide product was obtained and
8.9 9 of a second reaction product was isolated.
This product, which was shown to be
CF2BrcFBrocF2cF~cF3)ocF2cF2Br by its
fluorine nuclear magnetic resonance spectrum and its
high resolution mass spectrum, could be converted to
the principal product by reaction with zinc in
diethyl ether.
EXAMPLE 3
In accordance with the procedure of Example
2, bromine~, 30.6 9, was added dropwise to 112 9 of
CF2=CFO[CE'2CF(CF3)O]2CF2CF2COOCH3, prepared by
known procedures. The ester thus produced was hydro-
lyzed and the resultant salt was pyrolyzed according
to the procedure of Example 2. The isolated product,
33.1 g, was identified from its fluorine nuclear
magnetic resonance spectrum and snown to be
13
ll-bromo-perfluoro-5,8-dimethyl-3,6,9-trioxa-1-
undecene, cF2=cFo[cF2cF(cF3)o~2cF2cF2Br~ that is, the
compound of formula 1 wherein n is two.
EXAMPLE 4
Fifty grams of methyl perfluoro(4,7-dioxa-5-
methyl-8-nonenoate) was placed in a flask and cooled
in ice water. Chlorine was bubbled into the reaction
mixture until gas chromatographic analysis showed the
starting material to be consumed. Excess chlorine
was removed by bubbling nitrogen through the reaction
mixture. The dichloride product which was formed was
hydrolyzed to its sodium salt and pyrolyzed in tetra-
glyme by the procedure described for the dibromide in
Example 2. Twelve grams of pure product was obtained.
The product was identified by its infrared and
fluorine nuclear magnetic resonance spectrum and
shown to be 1,2-dichloro-perfluoro-3-oxa-5-oxohexane,
CF2ClCFClOCF2C(O)CF3, that is, the compound of
formula 2 wherein X and X are both Cl and n is one.
EXAMPLE 5
Five grams of the dichloroketone prepared in
Example 4 was added to 10 mL of diglyme, 1.5 g of zinc
metal and 0.1 g of zinc chloride. The mixture was
heated to reflux for 2 h. After cooling, gas chroma-
tographic analysis confirmed that all starting
material had reacted. The major reaction product was
isolated, 1.1 g, by distillation and identified from
its infrared spectrum, fluorine nuclear magnetic
resonance spectrum and high resolution mass spectrum,
all of which were consistent with the structure
l-chloro-perfluoro-3-oxa-5-oxo-1-hexene,
CFCl=CFOCF2C(O)CF3, that is, the compound of
formula 3 wherein n is one.
'33
EXAMPLE 6
36.2 g (0.08 mol) of CF3CFHOCF2CF(CF3)-
OCF2CF2CO2Na and 80 mL of tetraglyme were
stirred and heated in a 200 mL 3-neck flask fitted
5 with a thermometer, stirrer and distillation column
topped by a Dry Ice-cooled trap and nitrogen bubbler.
The salt largely dissolved and reaction was noted in
the temperature range 180 to 195. 17.9 g of color-
less distillate was obtained. Gas chromatography
and IR analysis confirmed the presence of
n
CF3CFHOCF2CCF3 (6.0 g, 28% yield), that is, the
compound of formula 2 wherein X is F, X is H and n
is 1, and
CF3CFHOCF2CF~CF3)OCF2CF2H (9.5 g, 31% yield).
EXAMPLE 7
1 g of potassium fluoride was added to a 50
mL round bottom flask fitted with a magnetic stirrer
and Dry Ice condenser with gas inlet topped by a
nitrogen bubbler. The flask was flamed out and
cooled, then 10 mL of diglyme and 6.2 g (0.02 mol) of
n
CF2ClCFClOCF2CCF3, prepared as in Example 4, were
added and stirred until all the RF dissolved. 5 g
(0.03 mol) of HFPO was then added. The reaction
mixture was stirred at room temperature for 30 min; a
clear, homogeneous yellow solution of the acyl
fluoride CF2ClCFClOCF2CF(CF3)OCF(CF3)COF, that is,
the compound of formula 4 wherein X and Xl are both
Cl, n is 1 and p is 0, in equilibrium with its KF
adduct was obtained. 5 mL of methanol was added to
the solution, resulting in an exothermic reaction.
After stirring for 15 min at room temperature, 100 mL
14
of water was added. A clear lower layer (10.5 9) was
separated and analyzed by gas chromatography, IR and
F NMR spectroscopy. The principal component,
b,p. 72-74 at 10 mm, was identified as
CF2clcFclocF2cF(cF3)ocF(cF3)co2cH3-
BEST MODE FOR CARR~-ING OUT THE INVENTION
The best mode presently contemplated for
carrying out the invention is demonstrated by Example
2 for the process of preparing the compound of
formula 1, Example 4 for the compound of formula 2,
Example 5 for the compound of formula 3, and Example
7 for the acyl fluoride of formula 4.
INDUSTRIAL APPLICABILITY
The fluorinated ketone of formula 2 can be
converted, by reaction with HFPO, followed by pyrol-
ysis of the resulting adduct, to a vinyl ether monomer
from which copolymers can be prepared which, after
hydrolysis, are water-wettable and dyeable and possess
ion-exchange properties.
The fluorinated ketone of formula 3 can be
converted to a copolymerizable monomer by the proced-
ure used for the ketone of formula 2; copolymers
derived therefrom are moldable and can be cured to
fluoroelastomers.
Although I have illustrated and described
the preferred embodiments of my invention, it is to
be understood that I do not limit myself to the
precise constructions herein disclosed and the right
is reserved to all changes and modifications coming
within the scope of the invention as defined in the
appended claims.
This application is a division of copending
Canadian Application Serial No. 422,605, filed
1983 March 01.
