Production of trifluorovinyl ethers

A two step process, each of the steps being novel, for the production of trifluorovinyl ethers by reaction of a siloxane with selected acyl fluorides or carboxylic anhydrides, is disclosed. Also disclosed is a novel silyl ester intermediate.

FIELD OF THE INVENTION 
Disclosed herein is a novel process for making trifluorovinyl ethers by 
reacting selected acyl fluorides or anhydrides with siloxanes, and then 
thermolyzing the resulting silyl ester to form the trifluorovinyl ether 
and a fluorosilane. The fluorosilane may be recycled to siloxane. 
TECHNICAL BACKGROUND 
Trifluorovinyl ethers are used commercially as comonomers in polymers, 
particularly as comonomers in highly fluorinated polymers which are often 
chemically and/or thermally relatively stable. The ethers are usually made 
by the gas or liquid phase thermolysis of the corresponding acyl fluoride 
over a bed of reactant and/or promoter. However, these reactions often 
give only fair yields of the trifluorovinyl ether and tend to generate 
relatively large amounts of toxic waste, which are difficult and expensive 
to dispose of. In the novel process described herein, particularly when 
run under the preferred conditions, good yields of the desired 
trifluorovinyl ether are obtained, and little toxic waste is generated, as 
most of the byproducts can be recycled in the process, and/or are 
otherwise useful. 
J. D. Citron, J. Organometal. Chem., vol. 30, p. 21-26 (1971) reported (in 
Table 1 therein) that siloxanes reacted with acyl fluorides to form 
carboxyl anhydrides and fluorosilanes. 
SUMMARY OF THE INVENTION 
This invention concerns a process for the production of trifluorovinyl 
ethers, comprising: 
a) reacting a compound containing the group --O(C.sub.2 F.sub.4)COF or the 
group --O(C.sub.2 F.sub.4)C(O)O(O)C(C.sub.2 F.sub.4)O-- with a siloxane; 
b) heating the silyl ester in the presence of a thermolysis catalyst, at a 
temperature of about 140.degree. C. to about 350.degree. C. to produce a 
trifluorovinyl ether and a fluorosilane; provided that where b) is carried 
out in the gas phase, said thermolysis catalyst is not a diaryl sulfone. 
This invention includes a process for the production of silyl esters, 
comprising, reacting a compound of the formula R.sup.1 [O(C.sub.2 
F.sub.4)COF].sub.z or a compound of the formula R.sup.1 [O(C.sub.2 
F.sub.4)C(O)O(O)C(C.sub.2 F.sub.4)O].sub.z R.sup.1 with a siloxane, to 
form a silyl ester, and wherein: 
R.sup.1 is a hydrocarbyl or substituted hydrocarbyl radical having z free 
valencies; and 
z is 1 or 2. 
This invention also concerns a process for the production of a 
trifluorovinyl ether, comprising, heating a silyl ester of the formula 
R.sup.1 [O(C.sub.2 F.sub.4)C(O)OSiR.sup.2.sub.3 ].sub.z, in the presence 
of a thermolysis catalyst, at a temperature of about 140.degree. C. to 
about 350.degree. C., to produce a trifluorovinyl ether and a 
fluorosilane, and wherein; 
R.sup.1 is a hydrocarbyl or substituted hydrocarbyl radical having z free 
valencies; 
each R.sup.2 is independently hydrocarbyl, substituted hydrocarbyl or an 
oxysilyl group; and 
z is 1 or 2; 
provided that when carried out in the gas phase said thermolysis catalyst 
is not a diaryl sulfone. 
This invention also includes a silyl ester of the formula R.sup.1 
[O(C.sub.2 F.sub.4)C(O)OSiR.sup.3.sub.3 ].sub.z, wherein: 
R.sup.1 is a hydrocarbyl or substituted hydrocarbyl radical having z free 
valencies; 
each R.sup.3 is independently hydrocarbyl, substituted hydrocarbyl, or 
oxysilyl; and 
z is 1 or 2. 
DETAILS OF THE INVENTION 
This invention deals with a process for producing trifluorovinyl ethers 
from selected acyl fluorides or carboxylic anhydrides. The process 
involves two steps, each of which is novel, and a novel intermediate is 
involved. The chemical reactions are believed to be: 
EQU --O(C.sub.2 F.sub.4)COF+.ident.SiOSi.ident..fwdarw.--O(C.sub.2 
F.sub.4)C(O)OSi.ident.+SiF (1) 
EQU --O(C.sub.2 F.sub.4)C(O)O(O)C(C.sub.2 
F.sub.4)O--+.ident.SiOSi.ident..fwdarw.2--O(C.sub.2 
F.sub.4)C(O)OSi.ident.(2) 
EQU --O(C.sub.2 F.sub.4)C(O)OSi.ident..fwdarw.--OCF=CF.sub.2 +CO.sub.2 
+.ident.SiF (3) 
Reaction conditions and catalysts are not shown in these equations, and in 
the complete process, either reaction (1) or reaction (2) would be done, 
followed by reaction (3). In these equations, only the "essential" parts 
of the reactants are shown. By "essential" is meant those parts of the 
reacting compounds that undergo chemical change during the process. 
The (parts of) the compounds that become the trifluorovinyl ether are 
--O(C.sub.2 F.sub.4)COF and --O(C.sub.2 F.sub.4)C(O)O(O)C(C.sub.2 
F.sub.4)O-- when an acyl fluoride or a carboxylic anhydride are used, 
respectively. By the grouping "(C.sub.2 F.sub.4)" is meant --CF.sub.2 
CF.sub.2 -- or --CF(CF.sub.3)--. The grouping --CF(CF.sub.3)-- is 
preferred. The open bonds on the one or two (in the acyl fluoride and 
anhydride respectively) oxygen atoms are to hydrocarbyl or substituted 
hydrocarbyl groups. In addition, the acyl fluoride may have one or two of 
the essential groups shown above, and the anhydride may have one or two 
anhydride groups. Thus, using either of these starting materials, 
trifluorovinyl ethers having one or two trifluorovinyl ether groups can be 
obtained. In the case of an anhydride which has two anhydride groups, the 
representation above is a "formal" one, as it is possible that the 
anhydride may be polymeric, oligomeric or cyclic. 
The following discussion of "R.sup.1 " is applicable not only to the 
immediately preceding compounds, but to all groups labeled "R.sup.1 " 
herein. The group attached to the free valence of the oxygen above may be 
designated as R.sup.1. Thus the acyl fluoride that is used can be R.sup.1 
[O(C.sub.2 F.sub.4)COF].sub.z where z is 1 or 2 and R.sup.1 is a 
hydrocarbyl or substituted hydrocarbyl radical. By "hydrocarbyl" is meant 
a monovalent or divalent group containing only carbon and hydrogen. By 
"substituted hydrocarbyl"0 is meant a monovalent or divalent group 
containing only carbon and hydrogen which contains inert substituents. By 
"inert" in this context is meant that they do not change or react 
chemically during the process. The term "radical" herein means a group 
which does not change chemically during a chemical reaction or process. 
Suitable substituents when R.sup.1 is substituted hydrocarbyl include, but 
are not limited to, fluorine, ether [between (substituted) hydrocarbyl 
segments], ester, sulfonyl fluoride, chloro, bromo, nitrile, sulfone 
[between (substituted) hydrocarbyl segments], sulfonate ester, and iodo. 
In one preferred embodiment all of the hydrogen atoms in R.sup.1 are 
replaced by fluorine atoms. In another preferred embodiment all of the 
hydrogen atoms in R.sup.1 are replaced by fluorine atoms, and R.sup.1 is 
substituted with one or more of ether, ester, or sulfonyl fluoride. In 
another preferred embodiment R.sup.1 is perfluoroalkyl, pentafluorophenyl, 
or perfluoroalkylene. In another preferred embodiment R.sup.1 is 
perfluoroalkyl or perfluoroalkylene substituted with one or more of ether, 
ester, or sulfonyl fluoride. Particularly preferred R.sup.1 groups are 
perfluoro-n-alkyl containing 1 to 12 carbon atoms, --[CF.sub.2 
CF(CF.sub.3)O].sub.n (CF.sub.2).sub.m CO.sub.2 CH.sub.3, and --[CF.sub.2 
CF(CF.sub.3)].sub.t O(CF.sub.2).sub.m SO.sub.2 F wherein n is 0 or an 
integer of 1 to 5, t is an integer of 1 to 5 and m is 2 or 3. The starting 
acyl fluorides can be made by known methods. See for example H. F. Mark, 
et al., Ed., Encyclopedia of Chemical Technology, 3rd Ed., John Wiley & 
Sons, New York, 1980, Vol. 10, p. 961 and W. Gerhartz, et al., Ed., 
Ullmanns Encyclopedia of Industrial Chemistry, 5th Ed., VCH, Weinheim, 
1988, Vol. All, p. 366-367. The starting carboxylic anhydrides can be made 
from the acyl fluorides (see below) if desired. 
Another of the needed ingredients for the process is a "siloxane". A 
siloxane is a compound that contains the grouping SiOSi with each of the 
free bonds to silicon bound to a hydrocarbyl, substituted hydrocarbyl, or 
oxysilyl group. By an oxysilyl group is meant the --OSi.ident. group in 
which the free valencies of the silicon can be bound to a hydrocarbyl, 
substituted hydrocarbyl or additional oxysilyl groups. In this way, 
siloxanes containing many individual siloxane groups are built up. 
However, the only groups ever bound to any silicon atom (with the 
exception of end groups in polymers) in the siloxanes used herein, are 
hydrocarbyl, substituted hydrocarbyl and oxysilyl. Thus, siloxanes can 
contain either one siloxane group, as in hexamethyldisiloxane, can be 
cyclic compounds and contain several siloxane groups, as in 
octamethylcyclotetrasiloxane, or can contain many siloxane groups as in 
poly(dimethylsiloxane). Useful siloxanes, include, but are not limited to, 
hexamethyldisiloxane, 1,3-diphenyl-1,1,3,3-tetramethyldisiloxane, 
hexaethyldisiloxane, 1,3-diethyl-1,1,3,3-tetramethyldisiloxane, 
hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, 
1,3,5-triphenyl-1,3,5-trimethylcyclotrisiloxane, poly(dimethylsiloxane), 
poly(methyl-3,3,3-trifluoropropylsiloxane), and mixed cyclics and polymers 
such as poly(dimethylsiloxane-co-phenylmethylsiloxane). Preferred 
siloxanes are hexamethyldisiloxane, hexamethylcyclotrisiloxane, 
octamethylcyclotetrasiloxane, and 
1,3-diethyl-1,1,3,3-tetramethyldisiloxane, and poly(dimethylsiloxane). A 
more preferred siloxane is hexamethyldisiloxane. 
Many siloxanes are commercially available. A short review of siloxanes is 
found in V. Bazant, et al., Organosilicon Compounds, vol. 1, Academic 
Press, New York, 1965, p. 45-51, and references therein and T. C. 
Kendrick, et al., in S. Patai, et al., Ed., The Chemistry of Organic 
Silicon Compounds, John Wiley & Sons, New York, 1989, Chap. 21. 
In the silyl esters used and claimed herein, it is preferred if each 
R.sup.2 and R.sup.3 is independently hydrocarbyl, more preferred if each 
R.sup.2 and R.sup.3 is independently phenyl or alkyl containing 1 to 4 
carbon atoms, and most preferred if each R.sup.2 and R.sup.3 is 
independently methyl or ethyl. 
The optional catalysts for reactions (1) and (2) are compounds that are 
sources of the carboxylate anion --O(C.sub.2 F.sub.4)CO.sub.2.sup.-. It is 
preferred if the optional catalyst is present in reaction (1) and (2). The 
carboxylate anion itself (added as a salt) is such a source. Other sources 
(which in the process can form the carboxylate anion) include but are not 
limited to, silanolates, fluoride, and carboxylates such as acetate and 
perfluorooctanoate. In the process it is believed these compounds react 
with the acyl fluoride or carboxylic anhydride to form the carboxylate 
catalyst. It is preferred if the counterion to the carboxylate catalyst is 
an alkali metal cation. Thus, it is preferred if all of the above catalyst 
precursors are added as their alkali metal salts. Preferred catalyst 
precursors (sources of catalyst) are potassium silanolates and potassium 
perfluorocarboxylates. 
Although not critical, it has been found useful to add 0.05 to 5 mole 
percent catalyst, based on equivalents of acyl fluoride present. Typically 
it is preferred if about 1 to 2 mole percent of the catalyst or source of 
catalyst is used. 
The thermolysis catalyst herein is an aprotic compound capable of 
desilylating a silyl ester of the formula --O(C.sub.2 F.sub.4)CO.sub.2 
Si.ident., or a diaryl sulfone. By an aprotic compound is meant a compound 
that does not contain active hydrogen, such as an alcohol, phenol, 
carboxylic acid, and primary and secondary amine. By capable of 
desilylating a silyl ester is meant that the compound causes the silicon 
atom to be removed from the oxygen atom of at least some of the silyl 
ester. This can occur through a simple chemical reaction in which the 
silyl ester is converted to another compound not having the Si--O-- bond. 
It also includes compounds that may cause a rapid reaction to occur in 
which the silicon atoms of the silyl ester molecules rapidly equilibrate 
with one another (i.e., the silicon atoms in effect rapidly "move" from 
one carboxyl group to another). This is illustrated in Experiment 1. 
Compounds capable of desilylating silyl esters (and are therefore 
thermolysis catalysts) include, but are not limited to, compounds which 
are a source of fluoride ion, perfluorocarboxylate salts (such as 
--O(C.sub.2 F.sub.4)CO.sub.2.sup.-, but other perfluorocarboxylates are 
also effective), alkoxides, carboxylates, carbonates, and silanolates. In 
general, oxyanions and anions of carbon and sulfur acids whose conjugate 
acids have a pKa of about 2 to about 32 when measured in dimethylsulfoxide 
(see F. G. Bordwell, Accts. Chem. Res., Vol. 21, p. 456 (1988) on how such 
measurements are made and for a list of pKas) are effective desilylation 
compounds. It is believed that the desilylation reactions are nucleophilic 
attacks on silicon, which have been reviewed, see, for example, A. R. 
Bassindale, et al., in S. Patai, et al., Ed., The Chemistry of Organic 
Silicon Compounds, John Wiley & Sons, New York, 1989, Chap. 13. Preferred 
thermolysis catalysts are sources of fluoride ion, fluorinated carboxylate 
salts, and silanolates. Especially preferred thermolysis catalysts are 
sources of fluoride ion, particularly an alkali metal fluoride, and most 
preferred is potassium fluoride. 
By a diaryl sulfone is meant a compound of the formula Ar--SO.sub.2 --Ar, 
where each Ar is independently an aryl or substituted aryl group. A 
preferred diaryl sulfone is diphenyl sulfone. A diaryl sulfone is not used 
as a thermolysis catalyst when the thermolysis is done in the gas phase. 
Although not critical, it has been found useful to add 1 to 5 mole percent 
of the catalyst or catalyst precursor based on silyl ester, when reaction 
(3) is carried out in the liquid phase. When the reaction is carried out 
in the gas phase, it is preferred to have a relatively large surface area 
of fluoride catalyst over which the vapor will pass. 
When reaction (3) is done in the liquid phase, it is preferred to have a 
cocatalyst present to facilitate reaction at a lower temperature. The 
cocatalyst is an organic compound which is capable of complexing with the 
cation of the fluoride ion source, for example the potassium ion of KF. 
Suitable compounds include, but are not limited to, crown ethers, linear 
polyethers, sulfones, and dialkyl pyrimidones. Although not critical, it 
has been found convenient to use 0.1 to 5 times the concentration of the 
thermolysis catalyst, of the cocatalyst. 
For reaction (1) the process temperature is not critical, but it has been 
found convenient to use a temperature of 25.degree. C. to 175.degree. C., 
preferably 40.degree. C. to 125.degree. C. Although solvents could be used 
in this reaction, if desired, there is no need to do so, and it is 
preferred not to use solvents to avoid having to separate a solvent and 
product after the reaction. Reaction times typically range from about 0.5 
to 24 hr., usually about to 5 hr. The reactants may optionally be 
agitated. 
If desired the product silyl ester of reaction (1) may be isolated by 
distillation (assuming it has a low enough molecular weight), but the 
temperature in the distillation should be kept low enough to avoid 
reaction (3). By a silyl ester herein is meant a compound containing the 
grouping --CO.sub.2 Si.ident., and which, for example, is believed made in 
reactions (1) and (2), and is the starting material for reaction (3). The 
esters made by (1) and (2) are novel, and are useful as intermediates for 
the production of trifluorovinyl ethers (as in reaction (3)). 
The ratio of reactants in (1), that is siloxane groups to acyl fluoride 
groups, is not critical, but it is usually preferable to have an excess of 
siloxane groups, since this ensures complete reaction of the acyl fluoride 
and/or anhydride and simplifies isolation of the silyl ester product. When 
using a compound containing one siloxane group (.ident.SiOSi.ident.), it 
is preferred if the ratio of siloxane to acyl fluoride is 4:1 to 1:1, more 
preferably 1.25:1 to 1.01:1. When there is more than one siloxane group in 
the siloxane compound, it is preferred if the ratio of siloxane groups to 
acyl fluoride groups is 5:1 to 1.5:1, more preferably 3:1 to 2:1. 
It is believed that sometimes in reaction (1), anhydride (as in reaction 
(2)) production may precede or accompany silyl ester formation. If that 
happens, anhydride may be converted to the silyl ester simply by 
continuing to heat the mixture. This is illustrated in Example 20. 
Reaction (3) may be carried out in the gas or liquid phases. As mentioned 
above, if done in the liquid phase, it is preferred to have a cocatalyst 
present. If done in the liquid phase the preferred temperature range is 
140.degree. C. to 250.degree. C., more preferably 160.degree. C. to 
175.degree. C. If done in the gas phase it is preferred if the temperature 
is 190.degree. C. to 250.degree. C. 
Reaction (3) must be done in the liquid phase if the starting silyl ester 
is not sufficiently volatile at the process temperatures. This will be 
more likely to occur if the silyl ester is formed from a polymeric or 
cyclic siloxane. When done in the liquid phase and run as a batch reaction 
a typical reaction time is 10 min. to 3 hr.; or the reaction may be run 
semi-batch (slow addition of the silyl ester to the reactor) over several 
hours. Agitation is optional. The reaction is most conveniently done in 
the liquid phase at ambient pressure. 
When reaction (3) is done in the gas phase typical contact times at 
elevated temperature are 10 sec. to 10 min., usually about 1 to 2 min. The 
reaction can be run at any convenient pressure, for example 1 Pa to 
5.times.10.sup.5 Pa, preferably at ambient pressure. Lower than ambient 
pressures are particularly useful for relatively nonvolatile silyl esters. 
It is preferred to have the catalyst for this process dispersed onto a 
solid support such as glass beads. Relatively finely divided catalyst or 
catalyst precursor is preferred. The weight ratio of catalyst to silyl 
ester used is not critical, and can range from 10:1 to 0.001:1. Typically 
it is 0.1:1 to 0.04:1. Preferred catalysts for the gas phase thermolysis 
are NaF, KF and CsF. 
When reaction (3) is done in either the gas or liquid phases, the process 
should be done under dry and oxygen free conditions to avoid unnecessary 
decomposition of the starting materials and/or products. It is convenient 
to carry out the reaction under an inert gas such as nitrogen. The 
products of the reaction are typically purified by distillation. 
One of the products of reaction (3) is a fluorosilane. This can be 
converted back to siloxane for further use in the process or for other 
uses. This is done according to reaction (4): 
EQU .ident.SiF+M(OH).sub.y .fwdarw..ident.SiOSi.ident.+MF.sub.y ( 4) 
where y is the charge on the M cation. The metal hydroxide or an equivalent 
of the metal hydroxide, such as the metal or metal oxide which can react 
with water to form the hydroxide. The conversion of the fluorosilane to a 
tractable siloxane is more difficult when there are 3 fluorine atoms on 
any single silicon atom, since such compounds tend to form insoluble 
resins. The reaction is carried out in the presence of water, and the 
hydroxide is either dissolved in, or slurried with, the water. Preferred 
metal hydroxides are the alkali hydroxides, and sodium, potassium 
hydroxides are especially preferred. Basic metal salts are contemplated 
equivalents of metal hydroxides. Alkaline earth fluorides, such as calcium 
fluoride, can best be made by reaction of the initially formed metal 
fluoride with CaO or Ca(OH).sub.2 (see Example 38). Siloxanes containing 
only one siloxane group are directly formed, but if cyclic or linear 
polymeric siloxanes are desired, further processing to obtain these as 
"pure" compounds may be necessary (see V. Bazant et al., supra). Thus it 
is preferred if the starting fluorosilane is a trihydrocarbylfluorosilane, 
more preferred if it is a trialkylfluorosilane in which each of the alkyl 
groups independently has 1 to 4 carbon atoms, and especially preferred if 
it is trimethylfluorosilane or dimethylethylfluorosilane. 
Reaction (4) is conveniently carried out at 0.degree. C. to 100.degree. C., 
preferably about 10.degree. C. to 60.degree. C. The reaction typically 
requires about 3-6 hr. at higher temperatures. The reaction is typically 
two phases, the organic and aqueous phases. These may be separated after 
the reaction, and the organic phase distilled to recover relatively 
volatile siloxanes. The pH of the aqueous layer is preferably maintained 
at about 7 or more throughout the process. The metal fluoride may be 
recovered by filtration if it is insoluble in water, or the water may be 
evaporated to recover soluble fluorides. The fluoride content of the metal 
fluoride may be recovered as HF by treating with strong acids. Substantial 
amounts of CO.sub.2 should be excluded from reaction (4). 
In reaction (4), the initial ratio of hydroxyl groups of the metal 
hydroxide to the total number of fluorines attached to silicon is 
preferably about 1:1, more preferably about 1.00:1 to 1.05:1. Larger 
excesses of strong inorganic bases may lead to silanolate formation and/or 
foaming, both of which are undesirable. This ensures that relatively pure 
products will be produced. It is preferred to use relatively high 
concentrations of the metal hydroxide, for example a 10-15% by weight 
solution of KOH, to keep the volume of the reaction low. If the 
fluorosilane is relatively low boiling, it may be necessary to do the 
reaction at higher than atmospheric pressure (trimethylfluorosilane boils 
at 18.degree. C.). 
The trifluorovinyl ethers produced by reaction (3) are useful as monomers 
in free radical copolymerizations. The copolymers produced are useful as 
heat and chemically resistant plastics and elastomers, see for example H. 
Mark., et al., Ed., Encyclopedia of Polymer Science, John Wiley & Sons, 
New York, vol. 7, 1987, p. 257-269 and vol. 16, 1989, p 614-626, which are 
hereby included by reference. These references also give details of the 
known procedures for free radically copolymerizing trifluorovinyl ethers. 
Tetrafluoroethylene is a preferred comonomer. 
Tetrafluoroethylene and perfluoropropyl vinyl ether are copolymerized in 
aqueous . . . or nonaqueous media . . . 
In aqueous copolymerization, water soluble initiators and a perfluorinated 
emulsifying agent are used. The tetrafluoroethylene is added continuously 
to the vinyl ether. Molecular weight and molecular weight distribution are 
controlled by a chain transfer agent. Sometimes a second phase is added to 
the reaction medium to improve the distribution of the vinyl ether in the 
polymer . . . ; a buffer is also added. 
In nonaqueous copolymerization, fluorinated acyl peroxides are used as 
initiators that are soluble in the medium . . . ; a chain transfer agent 
may be added for molecular weight control. 
Temperatures range from 15.degree. to 95.degree. C., and the pressures from 
0.45 to 3.55 MPa. The temperatures used for the aqueous process are higher 
than those for the nonaqueous process. 
Alkyl vinyl ethers tend to rearrange when exposed to free radicals . . . 
This could initiate a chain reaction that would result in incomplete 
rearrangement to the isomeric acid fluoride. Temperatures must be kept low 
enough to prevent termination by free-radical coupling. In the aqueous 
process, temperatures below 80.degree. C. minimize the number of acid end 
groups derived from vinyl ether transfer. In the nonaqueous process, 
temperature must also be limited to avoid excessive vinyl ether transfer 
as well as reaction with the solvent. End groups are stabilized by 
treating the polymer with methanol or ammonia . . . 
The polymer is separated from the medium and converted to useful forms such 
as melt-extruded cubes for melt processible applications.

In the below Examples and Experiments, the following abbreviations and 
names are used: 
Carbowax.RTM. 1000 (Trademark, Union Carbide Corp.)--polyethylene glycol of 
1000 molecular weight 
glyme--1,2-dimethoxyethane 
(HFPO).sub.2 -acid fluoride--CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF 
Me--methyl (--CH.sub.3) 
Mn--number average molecular weight 
3-n rbf--3-necked round bottom flask 
PPVE--perfluoro(propyl vinyl ether) 
PSEPVE--FSO.sub.2 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 OCF=CF.sub.2 
TAS--tris(dimethyamino)sulfonium 
THF--tetrahydrofuran 
TMS--trimethylsilyl 
TMSF--trimethylfluorosilane 
TosOH--p-toluenesulfonic acid 
It is to be understood that there is no intention to limit the invention to 
the below examples but the right is reserved to all changes coming within 
the scope of the claims. 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (16.6 g, 50 mmol) 
and hexamethyldisiloxane (8.1 g, 50 mmol) was treated with potassium 
trimethylsilanolate (300 mg). After the minor exotherm subsided, the 
mixture was heated in an oil bath at 75.degree. C. for 3 hr. .sup.19 F NMR 
showed (THF-d.sub.8): -79.6 and -85.9 (AB pattern, OCF.sub.2), -81.37 (t, 
J=9, CF.sub.3), -82.25 (s, CF.sub.3), -129.7 (s, CF.sub.2), -130.2 (d, 
CF), -157.5 (Me.sub.3 SiF). .sup.1 H NMR 0.37 (SiCH.sub.3). Spectra are in 
accord with the TMS ester. 
The crude ester was treated with 130 mg 18 crown-6, heated to reflux to 
remove remaining trimethylfluorosilane, cooled, and transferred to a 
dropping funnel. The mixture was added dropwise to a 3-n rbf maintained at 
195.degree. C. A slow N2 purge (ca. 30 mL/min) was used to carry volatile 
products to a collecting trap at -78.degree. C. There was obtained 12.6 g 
of colorless liquid consisting of PPVE (34%), C.sub.3 F.sub.7 OCHFCF.sub.3 
(17%), and TMSF (49%) (all mole percents). 
A sample of potassium trimethylsilanolate (0.5 g, 3.9 mmol) was treated 
with hexamethyldisiloxane (16.2 g, 100 mmol) and CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (34.2 g, 100 mmol). After the minor exotherm 
subsided, the mixture was heated in an oil bath at 60.degree. C. for 1 hr, 
75.degree. C. for 2.5 hr, and 85.degree. C. for 1 hr. The portion 
remaining in the reaction vessel was distilled to give a forerun (2.13 g; 
18 weight % TMSF, 68% siloxane, 5% TMS ester) and 30.3 g of colorless 
liquid with bp 139.degree.-140.degree.. .sup.19 F NMR (THF-d.sub.8): 
-79.41 and -86.15 (AB pattern, J=152, OCF.sub.2), -81.35 (t, J=7.1, 
CF.sub.3), -82.22 (s, CF.sub.3), -129.69 (s, CF.sub.2), -130.35 (d, J=19, 
CF). An additional 4.0 g of TMS ester product was obtained by vacuum 
transfer (at 0.1 mm). There remained 1.43 g of white solid, identified as 
CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 K. .sup.19 F NMR 
(THF-d.sub.8): -81.39 and -84.18 (AB pattern, J=164, OCF.sub.2), -81.36 
(t, J=6.9, CF.sub.3), -82.21 (s, CF.sub.3), -126.4 (brd s, CF), -129.86 
(s, CF.sub.2). 
EXAMPLE 3 
The procedure of Example 2 was repeated using potassium trimethylsilanolate 
(1.5 g, 12 mmol), hexamethyldisiloxane (80.8 g, 499 mmol), and CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (165.5 g, 499 mmol). Thermal program 
was similar, except temperature was maintained at 85.degree. C. for 2 hr, 
and 111.degree. C. for 1 hr. Distillation at ca 35 mm pressure afforded 
178.5 g, bp 54.degree.-55.degree. C. A minor amount of product appeared in 
the forerun, and the remaining CF.sub.3 CF.sub.2 CF.sub.2 
OCF(CF.sub.3)CO.sub.2 K was also coated with ester product. 
EXAMPLE 4 
A sample of potassium (HFPO).sub.2 acid salt obtained from Example 3 was 
treated with hexamethyldisiloxane (40.0 g, 247 mmol) and CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (82 g, 247 mmol). The resulting mixture was 
heated in stages, starting at 60.degree. C. and increasing over 4 hr to 
160.degree. C. (bath temperature) while low-boiling by-product was 
collected in a gas trap. Distillation at 25-45 mm gave 88.2 g of product 
which was redistilled at atmospheric pressure to give 87.3 g of CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3. 
EXAMPLE 5 
A sample of [CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO].sub.2 O (5.84 g, 
9.1 mmol) was treated with hexamethyldisiloxane (1.47 g, 9.1 mmol) and 
heated at 100.degree. C. for 48 hr. Although the reaction was rather slow, 
GC analysis showed that conversion of the anhydride to TMS ester was 
substantially complete (&gt;90%) after this heating period. 
EXAMPLE 6 
A dry 3-n rbf was charged with diphenyl sulfone (0.20 g, 1.0 mmol) and 
heated at 180.degree. C. under a slow nitrogen purge for 15 min. The 
reactor was cooled and charged with CF.sub.3 CF.sub.2 CF.sub.2 
OCF(CF.sub.3)CO.sub.2 K (184 mg, 0.5 mmol) and CF.sub.3 CF.sub.2 CF.sub.2 
OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (4.02 g, 10.0 mmol). The mixture was 
heated in a bath at 160.degree. C. for 1.5 hr during which time 2.0 g of 
volatile products were collected in a gas trap. .sup.19 F NMR analysis 
showed as major constituents (and wt % composition): PPVE (70%), C.sub.3 
F.sub.7 OCHFCF.sub.3 (9.8%), TMSF (20%). 
EXAMPLE 7 
A dry 3-n rbf was charged with cesium fluoride (75 mg, 0.5 mmol) and 
CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (4.02 g, 10 
mmol) and heated in an oil bath at 160.degree. C. No observable volatiles 
were collected after 45 min. the reaction mixture was cooled and treated 
with 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (130 mg, 1.0 
mmol). The mixture was heated in a bath at 160.degree. C. to consist of 
PPVE (41.2 mole %), TMSF (54.9%), C.sub.3 F.sub.7 OCHFCF.sub.3 (3.9%), and 
minor unidentified impurities. 
EXAMPLE 8 
A reactor for gas phase thermolyses was prepared as follows. A glass U-tube 
(1.5 cm diameter.times.18 cm height) was fitted at one end with an 
addition port and optional supplementary inert gas supply line. The other 
end of the U-tube was fitted with a ball-joint adapter leading to a series 
of gas trap collectors. Catalysts and solid supports were added to the 
reactor under inert atmosphere, and prior to use, the system was purged of 
adventitious water by heating at 225.degree.-250.degree. C. under a 
continuous stream of nitrogen. 
The above reactor was charged with a mixture of spray-dried potassium 
fluoride (6 g) and glass spheres (2-3 diameter, 35 mL) and heated in a 
bath at 225.degree. C. CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 
SiMe.sub.3 (1.0 mL) was added dropwise using a supplementary nitrogen 
carier flow of 30 mL/min. There was collected 0.75 mL (at -78.degree. C.) 
of colorless liquid. .sup.19 F NMR and GC analysis showed a ca. 94% 
conversion of the TMS-ester to a mixture of PPVE and TMSF. Only trace 
amounts of other components were present. The most prominent of these was 
C.sub.3 F.sub.7 OCHFCF.sub.3 (&lt;1 mole %). 
EXAMPLE 9 
Example 8 was repeated using the same reactor and catalyst/support charge. 
CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (16.20 g, 40.3 
mmol) was added dropwise over 1.5 hr. There was obtained 13.94 g of liquid 
product consisting of an equimolar mixture of PPVE and TMSF. Less than 
0.2% starting TMS ester remained, and less than 1% C.sub.3 F.sub.7 
OCHFCF.sub.3 was produced. 
EXAMPLE 10 
Example 8 was repeated using the same reactor and catalyst/support charge. 
CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (128.6 g, 
0.320 mmol) was added dropwise at ca. 20 g/hr using N.sub.2 carrier flow 
of 34 mL/min. There was obtained 109.1 g of liquid product consisting of 
PPVE (49.4 mole %), TMSF (48.4%) and C.sub.3 F.sub.7 OCHFCF.sub.3 (2.2%). 
Distillation using a 24" spinning band column gave 23.9 g of an azeotrope 
(74/26 TMSF/PPVE by weight), 23.5 g of intermediate fractions, and 51.6 g 
of &gt;99.8% purity PPVE. 
EXAMPLE 11 
A sample of CH.sub.3 O.sub.2 CCF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 
OCF(CF.sub.3)COF (52.25 g, 107 mmol) was treated with hexamethyldisiloxane 
(17.7 g, 109 mmol) and the resulting solution was treated with potassium 
trimethylsilanolate (0.5 g, 3.9 mmol). After the initial exotherm 
subsided, the mixture was heated in stages to 80.degree. C. at which 
temperature most of the expected TMSF was collected in a trap. The 
temperature was increased to 100.degree. C. for 0.5 hr and then 
125.degree. C. for 40 min to increase conversion to products. Distillation 
(0.1 mm) afforded 53.7 g of colorless liquid, bp 63.degree. C. .sup.19 F 
NMR (THF-d.sub.8 /F11): -79.0 and -84.1 (overlapping AB patterns, J=141, 
OCF.sub.2), -79.91 (m, CF.sub.3), -82.13 and -82.16 (singlets, CF.sub.3 's 
for two diastereomers), -82.9 (m, OCF.sub.2), -121.17 and -121.24 (equally 
intense triplets, J=2.9, CF.sub.2, -130.05 (apparent t, J=18, CF), -144.9 
(t, J=22, CF). .sup.1 H NMR 3.93 (s, OCH.sub.3), 0.39 (s, SiCH.sub.3). 
EXAMPLE 12 
Gas phase thermolysis was carried out using a reactor containing 
spray-dried KF and glass beads (described in Example 8) modified to 
accommodate a glass side-arm and distillation flask on the feed side. The 
U-tube reactor was maintained at 225.degree.-230.degree. C. during the 
reaction. A sample of MeO.sub.2 CCF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 
OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (4.6 g, 8.4 mmol) was slowly added from 
the distillation flask by reducing the pressure to 0.05 mm and heating the 
flask in a separate bath at ca. 70.degree. C. Products were collected in a 
gas trap cooled at -78.degree. C. There was obtained 2.66 g of colorless 
liquid consisting of a mixture of Me.sub.3 SiF and CF.sub.2 =CFOCF.sub.2 
CF(CF.sub.3)OCF.sub.2 CF.sub.2 CO.sub.2 Me as shown by comparison with 
authentic samples (GC) and .sup.19 F NMR (THF-d.sub.8 /F.sub.11): -79.9 
(m, CF.sub.3), -82.9 and -84.6 (centers of OCF.sub.2 m's), -113.7 (dd, 
J=65, 85, CF), -121.3 (m, CF.sub.2), -121.7 (dd of t's, J=85, 112, 6, CF), 
-136.65 (dd of t's, J=65, 112, 6, CF), -144.9 (t, J=21.6, CF), -157.5 (m, 
SiF). 
EXAMPLE 13 
A sample of FSO2CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (35.2 g, 101 mmol) was 
treated with hexamethyldisiloxane (16.4 g, 101 mmol) and potassium 
trimethylsilanolate (0.38 g, 3 mmol) at 25.degree. C. The mixture was 
heated in stages from 50.degree. C. to 97.degree. C., and the temperature 
was maintained at 97.degree. C. for 1.5 hr. Distillation at 0.2 mm gave a 
small forerun and 35.2 g of colorless oil with bp =28.degree. C. .sup.19 F 
NMR (THF-d.sub.8): +45.30 (apparent pentet, J=5.7, FSO.sub.2), -81.92 (s, 
CF.sub.3), -77.24 and -83.59 (AB pattern, J=147, with lower-field portion 
exhibiting additional J=18.5), -112.08 (s, CF.sub.2), -130.16 (d, J=18.2, 
CF), in accord with FSO.sub.2 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 
SiMe.sub.3. 
EXAMPLE 14 
A mixture of FSO2CF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 OCF(CF.sub.3)COF 
(7.14 g, 13.9 mmol) and hexamethyldisiloxane (2.26 g, 13.9 mmol) was 
treated with potassium trimethylsilanolate (64 mg, 0.5 mmol) and heated at 
60.degree. C. for 0.5 hr, 80.degree. C. for 0.5 hr, and 125.degree. C. for 
1.5 hr. Distillation at 0.05 mm gave a forerun (0.8 g) and the major 
fraction (4.9 g) at 42.degree.-43.degree. C. Some of the desired product 
remained in the distillation pot along with the corresponding potassium 
carboxylate. .sup.19 F NMR (THF-d.sub.8): +45.4 (m, FSO2), -77.8 to -80.0 
(overlapping lower-field OCF.sub.2 AB and CF.sub.3), -82.11 and -82.15 
(singlets, CF.sub.3), -84.0 (high-field portion of AB pattern, J=140, 
OCF.sub.2), -111.9 (m, CF.sub.2), - 130.0 (m, CF), -144.4 (overlapping 
m's, CF). .sup.1 H NMR 0.38 (s). Spectra are in accord with FSO.sub.2 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3. 
EXAMPLE 15 
A sample of FSO.sub.2 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CF.sub.2 
OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (4.8 g, 8.2 mmol) was added dropwise over 
1 hr to the U-tube reactor (described in Example 8) containing KF glass 
beads at 220.degree.-230.degree. C. There was obtained 4.07 g of colorless 
liquid consisting of a ca. 1/1 mixture of PSEPVE and TMSF. .sup.19 F NMR 
(THF-d.sub.8): +45.3 (m, FSO.sub.2), -79.1 (m, CF.sub.2), -79.9 (m, 
CF.sub.3), -84.5 (m, CF.sub.2), -112.1 (m, SO.sub.2 CF.sub.2), -113.2 (dd, 
J=66, 84, CF), -121.41 (dd of t's, J=84, 112, CF), -136.45 (dd of t's, 
J=66, 112, 6, CF), -157.7 (m, FSiMe.sub.3). 
EXAMPLE 16 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (6.0 g, 18 mmol) 
and cesium fluoride (200 mg, 1.3 mmol) was treated with 
hexamethylcyclotrisiloxane (1.5 g, 6.8 mmol). The mixture was then treated 
with TAS Me.sub.3 SiF.sub.2 (50 mg) and allowed to stand for two days. The 
mixture was heated in an oil bath at 130.degree.-150.degree. C. to provide 
2.2 g of colorless liquid. .sup.19 F NMR analysis showed two major 
products, PPVE and C.sub.3 F.sub.7 OCHFCF.sub.3 in a ca. 73/27 ratio. 
EXAMPLE 17 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (16.6 g, 50 mmol) 
and hexamethylcyclotrisiloxane (4.1 g, 18.5 mmol) was treated with 
potassium silanolate (300 mg, 2.3 mmol). After the exotherm subsided, the 
homogeneous solution was heated to 160.degree. C. (internal temperature) 
while 3.0 mL of colorless liquid was collected in a gas trap. Bulk of this 
volatile portion was dimethyldifluorosilane; a minor amount of unreacted 
(HFPO).sub.2 acid fluoride was also collected. The mixture was cooled to 
25.degree. C. and 18-crown-6 (80 mg, 0.3 mmol) was added. The mixture was 
heated to 150.degree. C., then 175.degree.-180.degree. C., at which 
temperature 11.2 mL of colorless liquid was collected. .sup.19 F NMR 
(THF-d.sub.8) showed -81.84 (t, J=7.4, CF.sub.3), -86.35 (m, CF.sub.2 O), 
-114.0 (dd, J=66, 85, vinyl CF), -122.1 (dd of triplets, J= 85, 112, 5.7, 
vinyl CF), -129.96 (s, CF.sub.2), -135.94 (dd of triplets, J=66, 112, 5.8, 
vinyl CF), -147.2 (d of m's, J=51, CHF), consistent with a ca 95/5 ratio 
of PPVE/C.sub.3 F.sub.7 OCHFCF.sub.3). Small amounts of fluorine-ended 
dimethylsiloxane oligomers (predominantly Me.sub.2 FSiOSiMe.sub.2 F) were 
present, as evidenced by septets at -131.9 and -131.15. 
EXAMPLE 18 
A 4.04 g sample of trimethylsilyl-terminated dimethylsiloxane polymer (mol. 
wt.=9430) was treated with potassium fluoride (100 mg), potassium 
trimethylsilanoate (300 mg), and Carbowax.RTM. 1000 (80 mg) and heated at 
125.degree. C. for 15 min. The mixture was cooled to 25.degree. C. and 
treated with CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (17.0 g, 51 
mmol). The mixture was heated gradually in an oil bath from 50.degree. C. 
to ca. 190.degree. C., collecting 10.05 g of volatile products in a gas 
trap at -78.degree. C. .sup.19 F NMR analysis showed a mixture of PVE (75 
mole %), C.sub.3 F.sub.7 OCHFCF.sub.3 (11%), and (HFPO).sub.2 -acid 
fluoride (5%). There remained 3.00 g of by-product ketone [C.sub.3 F.sub.7 
OCF(CF.sub.3)].sub.2 CO in the pot. 
EXAMPLE 19 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (7.54 g, 22.7 
mmol) and hexamethylcyclotrisiloxane (1.68 g, 7.6 mmol) was treated with 
potassium trimethylsilanolate (80 mg, 0.63 mmol). After the mild exotherm 
subsided and solid trisiloxane had disappeared, the reaction mixture was 
stirred for an additional 0.5 hr. Volatiles were transferred under vacuum 
(0.1 mm) to give 7.45 g of colorless liquid. Storage at -25.degree. C. 
provided 6.1 g (84% yield) of a lower layer. .sup.19 F NMR (THF-d.sub.8) 
featured two AB patterns -79.80 and -86.15 (J=160), and -79.80 and -86.30 
(J=160, OCF.sub.2), -81.8 (t) and -81.95 (s, CF.sub.3 's), -129.98 (s, 
CF.sub.2), -131.98 (d, J=19.6, CF). IR featured C=O bands at 1868 and 1802 
cm.sup.-1. Spectral data are in accord with the anhydride: [CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO].sub.2 O. 
EXAMPLE 20 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (15.7 g, 47.3 
mmol) and octamethylcyclotetrasiloxane (14.0 g, 47.2 mmol) was treated 
with potassium trimethylsilanolate (256 mg, 2.0 mmol) and stirred at 
ambient temperature for 1.2 hr. GC and .sup.19 F NMR analyses of an 
aliquot showed that starting acid fluoride and the anhydride characterized 
in Example 19 were the predominant fluorocarbon species present. The 
mixture was then heated at 75.degree. C., and the temperature was 
gradually increased to 186.degree. C. over 3 hr. GC analysis showed that 
acid fluoride and the anhydride had been nearly completely consumed. 
.sup.1 H NMR showed SiCH.sub.3 signals at 0.404 and 0.396 (characteristic 
of RfCO.sub.2 SiMe.sub.2) as well as SiCH.sub.3 at 0.15-0.09. .sup.19 F 
NMR was likewise consistent with a mixture of 
dimethyl(perfluoroalkylcarboxy)-terminated and dimethylfluoro-terminated 
dimethylsiloxane oligomers. GC/MS analysis of these intermediates in a 
similar experiment provided good evidence for the formation of 
intermediate silyl esters. For example, the observed m/z of 538.999878 had 
the elemental composition of C.sub.11 H.sub.15 O.sub.5 Si.sub.3 F.sub.12 
(calc'd.=539.0035726) and is assigned to [C.sub.3 F.sub.7 
OCF(CF.sub.3)CO.sub.2 SiMe.sub.2 OSiMe.sub.2 OSiMe.sub.2 F--Me]. 
Similarly, observed m/z=613.005127 had the elemental composition [C.sub.3 
H.sub.21 F.sub.12 O.sub.6 Si.sub.4 (calc'd.=613.0223659) and is assigned 
to [C.sub.3 F.sub.7 OCF(CF.sub.3)CO.sub.2 SiMe.sub.2 O(SiMe.sub.2 O).sub.2 
SiMe.sub.2 F--Me]. The mixture was cooled to 25.degree. C., and 18-crown-6 
(132 mg, 0.5 mmol) was added. Upon heating at 160.degree.-185.degree. C. 
(bath temperature), 8.5 mL (11.4 g) of colorless volatiles were collected 
in a gas trap. .sup.19 F NMR analysis showed this to consist of PPVE (80 
mole %), C.sub.3 F.sub.7 OCHFCF.sub.3 (10%), and Me.sub.2 SiFOSiMe.sub.2 F 
(9%). There remained after thermolysis 12.6 g of liquid and a small amount 
of insoluble material. NMR and GC/MS showed the liquid consisted of 
dimethylfluoro-terminated dimethylsiloxane oligomers (Me.sub.2 
FSiO(Me.sub.2 SiO).sub.n SiMe.sub.2 F, n=0 to 13) along with a small 
amount of cyclic trimer, tetramer, and pentamer (D.sub.3 to D.sub.5). For 
example (n=3), observed m/z=377.067902; calc'd. m/z=377.0723831 for 
C.sub.9 H.sub.27 F.sub.2 O.sub.4 Si.sub.5 (M-CH.sub.3). 
EXAMPLE 21 
Example 20 was repeated using CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF 
(17.2 g, 51.8 mmol), freshly distilled octamethylcyclotetrasiloxane (7.7 
g, 26 mmol), and potassium trimethylsilanolate (256 mg, 2.0 mmol). 
18-Crown-6 (130 mg) was added after GC analysis showed substantial 
consumption of the intermediate anhydride. Prior to liberation of PPVE, 
there was collected 1.11 g of volatiles consisting (mol %) of Me.sub.2 
SiF.sub.2 (52), C.sub.3 F.sub.7 OCHFCF.sub.3 (13), Me.sub.3 SiF (14), and 
(HFPO).sub.2 -acid fluoride (21). Thermolysis in the presence of 
18-crown-6 gave 12.1 g of condensate consisting (wt %) of PPVE (81), 
C.sub.3 F.sub.7 OCHFCF.sub.3 (7), Me.sub.2 SiFOSiMe.sub.2 F (7.6), and 
Me.sub.2 SiF.sub.2 (5). Yield of PPVE was thus ca. 75%. 
EXAMPLE 22 
A 3-n rbf fitted with reflux condenser, internal liquid and vapor 
temperature sensors, was connected to a gas trap for the collection of 
lower boiling components. The flask was charged with CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (17.2 g, 52 mmol) and 
octamethylcyclotetrasiloxane (8.0 g, 27 mmol) and then potassium 
trimethylsilanolate (256 mg, 2 mmol). After the exotherm subsided, the 
mixture was heated in stages to 150.degree. C. (internal temperature ca. 
135.degree. C.) over a period of 5.5 hr. Collection of volatiles began 
when the internal temperature reached ca. 70.degree. C., but only 1.8 mL 
of volatiles was obtained. The major part of this trap liquid was Me.sub.2 
SiF.sub.2, minor components included (HFPO).sub.2 -acid fluoride and 
C.sub.3 F.sub.7 OCHFCF.sub.3. The pot residue was treated with 18-crown-6 
(130 mg, 0.5 mmol) and heated at 150.degree. C. There was obtained 12.1 g 
of liquid in the trap after warming to 15.degree. C. .sup.19 F NMR showed 
(mol %) the following species: PPVE (72.0), C.sub.3 F.sub.7 OCHFCF.sub.3 
(5.9), Me.sub.2 FSiOSiMe.sub.2 F (10.6), Me.sub.2 SiF.sub.2 (11.7). The 
pot residue was processed to provide 5.8 g of oil shown by NMR and GC/MS 
to consist of a series of fluorine-terminated dimethylsiloxane oligomers 
containing from 2 to 14 silicon atoms. 
EXAMPLE 23 
A 3-n rbf fitted with reflux condenser, internal liquid and vapor 
temperature sensors, was connected to a gas trap for the collection of 
lower boiling components. The flask was charged with CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (16.5 g, 9.7 mmol) and 
octamethylcyclotetrasiloxane (7.4 g, 4.8 mmol) and potassium 
trimethylsilanolate (256 mg, 2 mmol). After the exotherm subsided, the 
mixture was heated in stages to 150.degree. C. (internal temperature ca. 
135.degree. C.) over a period of 2.5 hr. Collection of volatiles began 
when the internal temperature reached ca. 70.degree. C., but only 1.25 mL 
of volatiles was obtained. The major part of this trap liquid was Me.sub.2 
SiF.sub.2, minor components included (HFPO).sub.2 -acid fluoride and 
C.sub.3 F.sub.7 OCHFCF.sub.3. The pot residue was then heated at 
150.degree.-200.degree. C. for ca. 7 hr. There was obtained 14.3 g of 
liquid in the trap. From the weight and composition (determined by GC and 
NMR) the yield of PPVE was determined as 74%. C.sub.3 F.sub.7 OCHFCF.sub.3 
was the most prominent by-product, and the ketone [C.sub.3 F.sub.7 
OCF(CF.sub.3)].sub.2 CO was a minor one. Me.sub.2 FSiOSiMe.sub.2 F and 
Me.sub.2 SiF.sub.2 were the volatile fluorosilanes present in the trap. 
The pot residue was comparable to previous examples and consisted of a 
series of fluorine-terminated dimethylsiloxane oligomers containing from 2 
to 14 silicon atoms. 
EXAMPLE 24 
A 3-n rbf fitted with reflux condenser, internal liquid and vapor 
temperature sensors, was connected to a gas trap for the collection of 
lower boiling components. The flask was charged with CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (15.3 g, 46 mmol) and cesium fluoride (200 mg, 
1.3 mmol). Hexamethylcyclotrisiloxane (3.8 g, 17.1 mmol) was added in one 
portion. After the solid dissolved and the exotherm subsided, the mixture 
was heated in stages to 175.degree. C. Collection of volatiles began when 
the internal temperature reached ca. 120.degree. C. There was obtained 7.5 
mL (at -78.degree. C.) of liquid in the trap after ca. 4 hr. Volatile 
product was fractionated by warming to -50, -30, 0, and then 15.degree. C. 
to remove trapped CO.sub.2 and the bulk of dimethyldifluorosilane. .sup.19 
F NMR of the remaining 7.45 g (5.8 mL) of volatile product showed PPVE, 
C.sub.3 F.sub.7 CHFCF.sub.3, and (HFPO).sub.2 -acid fluoride in a 73/13/13 
ratio. Continued thermolysis of the pot residue produced a small amount 
(1.0 mL, 1.52 g) of additional pyrolysate which was predominantly PPVE by 
.sup.19 F NMR analysis. 
EXAMPLE 25 
A 3-n rbf fitted with reflux condenser, internal liquid and vapor 
temperature sensors, was connected to a gas trap for the collection of 
lower boiling components. The flask was charged with CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (16.6 g, 50 mmol) and hexamethylcyclotrisiloxane 
(4.1 g, 18.5 mmol) and then potassium trimethylsilanolate (300 mg, 2.3 
mmol). After the solid dissolved and the exotherm subsided, the mixture 
was heated in stages to 180.degree. C. (internal temperature ca. 
160.degree. C.) over a period of 1.0 hr. Collection of volatiles began 
when the internal temperature reached ca. 100.degree. C., but only 3.0 mL 
of volatiles was obtained. The major part of trap liquid was Me.sub.2 
SiF.sub.2, minor components included (HFPO).sub.2 -acid fluoride and 
C.sub.3 F.sub.7 OCHFCF.sub.3. After standing for 18 hr, the pot residue 
was treated with 18-crown-6 (80 mg, 0.3 mmol) and heated at 
175.degree.-180.degree. C. There was obtained 11.5 mL (at -78.degree. C.) 
of liquid in the trap after ca. 1 hr. Volatile product was fractionated by 
warming to -50, -30, 0, and then 15.degree. C. to give 11.2 mL of liquid. 
.sup.19 F NMR (THF-d.sub.8 /F.sub.11): -81.84 (t, J=7.4, CF.sub.3), -86.35 
(m, OCF.sub.2), -114.00 (dd, J=66, 85, vinyl CF), -122.10 (dd of t's, 
J.sub.t =5.7, J.sub.d =85, 112), -129.96 (s, CF.sub.2), -135.94 (dd of 
t's, J.sub.t =5.8, J.sub.d =66, 112, vinyl CF); minor signals at -130.18, 
-131.15, and -131.9 due to FMe.sub.2 Si- fragments; and d of m's at -147.2 
characteristic of C.sub.3 F.sub.7 OCHFCF.sub.3. PPVE purity was estimated 
as about 95%. 
EXAMPLE 26 
A 3-n rbf fitted with reflux condenser, internal liquid and vapor 
temperature sensors, was connected to a gas trap for the collection of 
lower boiling components. The flask was charged with TMS-terminated 
polydimethylsiloxane (4.04 g, 3.82 mL, mol wt. ca. 9400), potassium 
fluoride (100 mg), potassium trimethylsilanolate (300 mg), and 
Carbowax.RTM. 1000 (80 mg). The mixture was heated at 125.degree. C. for 
20 min, cooled to 25.degree. C. and treated with CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF (17.0 g, 51 mmol). The mixture was heated 
gradually and in stages to 190.degree. C. (bath temperature) over a period 
of 4.0 hr. Collection of volatiles began when the internal temperature 
reached ca. 70.degree. C. There was obtained 8.5 mL (10.1 g) after warming 
the volatile fraction to 15.degree. C. .sup.19 F NMR analysis showed this 
product consisted of a mixture of PPVE (75%), C.sub.3 F.sub.7 
OCHFCF.sub.3) (11%), (HFPO).sub.2 (5%), and a minor quantity of 
unidentified material. The fluorocarbon fraction (3.0 g) obtained from the 
pot residue consisted mainly of a mixture of diastereomeric ketones of the 
structure [C.sub.3 F.sub.7 OCF(CF.sub.3)].sub.2 CO. 
EXAMPLE 27 
A mixture of [CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO].sub.2 O (2.57 g, 
4.0 mmol) and hexamethyldisiloxane (648 mg, 4.0 mmol) in a sealed glass 
vial was heated in a bath at 100.degree. C. The (initially) two-phase 
mixture was stirred vigorously using a small magnetic stir bar. 
Composition of the mixture was determined by GC analysis using authentic 
standards. Approximate composition (anhydride/siloxane/CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3) varied with time as follows: 
______________________________________ 
18 hr 60/30/10 
42 hr 40/20/36 
96 hr 25/11/64 
120 hr 20/8/73 
______________________________________ 
EXAMPLE 28 
A mixture of [CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO].sub.2 O (2.57 g, 
4.0 mmol) and hexamethyldisiloxane (648 mg, 4.0 mmol) was treated with 
CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 K (29 mg, 0.08 mmol) in a 
sealed glass vial. The reaction mixture was heated in a bath at 
100.degree. C. The (initially) two-phase mixture was stirred vigorously 
using a small magnetic stir bar. Composition of the mixture was determined 
by GC analysis using authentic standards. Approximate composition 
(anhydride/siloxane/CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 
SiMe.sub.3) varied with time as follows: 
______________________________________ 
3.5 hr 52/23/25 
18 hr 31/4/65 
42 hr 15/2.5/83 
96 hr 9/0/91 
______________________________________ 
EXAMPLE 29 
A mixture of [CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO].sub.2 O (2.57 g, 
4.0 mmol) and hexamethyldisiloxane (648 mg, 4.0 mmol) was treated with 
Me.sub.3 SiOK (10 mg, 0.08 mmol) in a sealed glass vial. The reaction 
mixture was heated in a bath at 100.degree. C. The (initially) two-phase 
mixture was stirred vigorously using a small magnetic stir bar. 
Composition of the mixture was determined by GC analysis using authentic 
standards. Approximate composition (anhydride/siloxane/CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3) varied with time as follows: 
______________________________________ 
40 min 35/18/47 
70 min 24/18/58 
40 hr 1.3/1.6/97.0 
94 hr 0.9/1.4/97.7 
______________________________________ 
EXAMPLE 30 
A sample of fluorine-ended dimethylsiloxane oligomers (2.00 g, est. Mn=400, 
5 mmol) obtained from the reaction of (HFPO).sub.2 -acid fluoride and 
octamethylcyclotetrasiloxane was treated with calcium carbonate (0.5 g) 
and calcium oxide (0.25 g) and heated for 1.5 hr at 150.degree. C., then 
0.75 hr at 200.degree. C. without change in composition. The sample was 
then treated with Ca(OH).sub.2 (0.3 g) and heated at 200.degree. C. for 40 
min. GC analysis of the crude mixture showed a low conversion to the 
cyclic trimer, tetramer (D.sub.4), and pentamer (D.sub.5) of 
dimethylsiloxane. 
EXAMPLE 31 
A sample of fluorine-ended dimethylsiloxane oligomers obtained as in 
Example 30 (5.0 g) was treated with Ca(OH).sub.2 (0.75 g) and heated at 
220.degree. C. for 0.5 hr. The pressure was then reduced to 0.1 mm and 
0.45 g of distillate was obtained which consisted mainly of D.sub.3, 
D.sub.4, and D.sub.5. The mixture was cooled to 25.degree. C. and treated 
with 75 mg KOH and again heated at 220.degree. C./0.1 mm to provide 2.70 g 
of a mixture of D.sub.3 -D.sub.9. Structures were confirmed by GC/MS. 
EXAMPLE 32 
A mixture of fluorine-ended dimethylsiloxane oligomers obtained as in 
Example 30 (5.24 g), calcium hydroxide (0.9 g), potassium hydroxide (75 
mg), and glyme (25 mL) was heated at reflux for 3 hr. Solid was removed by 
filtration, and the filtrate was treated with water (50 mL). The top layer 
was dissolved in methylene chloride and washed several times with water, 
dried, and stripped to give 4.74 g of light yellow oil. Kugelrohr 
distillation afforded 1.95 g of colorless oil, consisting mainly of 
D.sub.4 and D.sub.5 but containing also D.sub.6 -D.sub.12. The pot residue 
was treated with 50 mg KOH and heated under vacuum (150.degree. C., 0.5 
mm). The volatiles from this fraction (2.40 g) consisted of D.sub.3 
-D.sub.7 with very small amounts of D.sub.8 and D.sub.9. 
EXAMPLE 33 
A mixture of fluorine-ended dimethylsiloxane oligomers obtained as in 
Example 30 (8.12 g, Mn ca. 3000), calcium hydroxide (0.2 g), potassium 
hydroxide (50 mg), and glyme (35 mL) was heated at reflux for 3 hr. The 
mixture was filtered, stripped, dissolved in CH.sub.2 Cl.sub.2, washed 
with water, dried and stripped. The resulting light yellow oil was treated 
with KOH (25 mg) and heated in an oil bath at 170.degree. C. (0.2 mm) to 
provide 8.55 g of colorless distillate consisting of 8.00 g of D.sub.3 
-D.sub.7 and ca. 0.5 g residual solvent. Yield of cyclic oligomers was 
thus &gt;98%. 
EXAMPLE 34 
A glass vial of 20 mL capacity (cleaned by rinsing consecutively with 
distilled water, acetone, THF; dried at 115.degree. C. for 24 hr and 
stored in an atmosphere of dry nitrogen) was charged with CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (332 mg, 1.0 mmol) and 
hexamethyldisiloxane (162 mg, 1.0 mmol) and sealed using a polypropylene 
screw cap. The vial was heated in a sand bath maintained at 100.degree. C. 
The reaction was monitored by GC analysis. The vial was cooled to 
-25.degree. C., then warmed sufficiently to obtain a single liquid phase 
of reactants and products. After 20 hr under these conditions, two 
fluorocarbon-containing components were present: CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)COF 44 hr, the composition consisted of acid 
fluoride (18.6%), anhydride (2.3%), and silyl ester (79.1%). 
EXAMPLE 35 
A glass vial of 20 mL capacity (cleaned by rinsing consecutively with 
distilled water, acetone, THF; dried at 115.degree. C. for 24 hr and 
stored in an atmosphere of dry nitrogen) was charged with CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (498 mg, 1.5 mmol) and 
1,1,2,2-tetramethyl-1,3-diethyldisiloxane (285 mg, 1.5 mmol) and a small 
teflon-coated stir bar and sealed using a polypropylene screw cap. The 
vial was heated in a sand bath maintained at 100.degree. C. The reaction 
was monitored by GC analysis. The vial was cooled to -20.degree. C., then 
warmed sufficiently to obtain a single liquid phase of reactants and 
products (ca. 0.degree. C.). After 13 hr under these present: CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)COF (83 mole %) and CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.2 Et (17%). After 37 hr, the 
composition consisted of acid fluoride (51.9%), anhydride (2.8%), and 
silyl ester (45.3%). 
EXAMPLE 36 
A 3-n rbf was charged with calcium hydroxide (1.59 g, 21.5 mmol), potassium 
hydroxide (25 mg), and water (30 mL). The mixture was cooled to 0.degree. 
C. and treated with trimethylfluorosilane (5.0 mL at 0.degree. C., 4.0 g, 
43 mmol). After addition was complete, the temperature was allowed to 
increase to 20.degree. C. The mixture was heated to 50.degree. C., and the 
reflux condenser was replaced with a still head. Product 
hexamethyldisiloxane and trimthylsilanol was collected in the 
lower-boiling fraction which began at ca. 77.degree. C. Separation of the 
two liquid layers in the distillate provided 2.45 g of organic material 
which consisted of trimethylsilanol (28%) and hexamethyldisiloxane (68%). 
Addition of a trace amount of toluenesulfonic acid facilitated the 
condensation of trimethylsilanol, and resulted in hexamethyldisoloxane of 
&gt;99% purity. Solid remaining in the distillation pot was filtered and 
dried to give 1.75 g of white solid. 
EXAMPLE 37 
A solution of calcium acetate hydrate (16.9 g, 95.9 mmol) in water (50 mL) 
at 2.degree.-4.degree. C. was treated with trimethylfluorosilane (8.83 g, 
96 mmol). The vessel was sealed and allowed to warm to 25.degree. C. over 
2 hr. Distillation at atmospheric pressure afforded 6.64 g of colorless 
liquid which consisted of TMSF (2.5%), TMSOH (2.4%), and (TMS).sub.2 O 
(95.2%). The pot residue was treated with an antifoaming agent, Dow 
Corning DB-31, and again subjected to distillation to provide an 
additional 0.5 g of hexamethyldisiloxane. The remaining solid was filtered 
and dried to give 5.95 g of material. Elemental analysis confirmed that 
acetate was present in this product. 
EXAMPLE 38 
A solution of KOH (86.2 mequiv.) in water (35 mL) was prepared in a 70 mL 
Fisher-Porter bottle and cooled to 0.degree. C. Trimethylfluorosilane 
(10.0 mL, 7.93 g) was added, and the vessel was sealed. The mixture was 
warmed to 25.degree. C. and stirred for 1.75 hr. The vessel was 
pressurized with N.sub.2 (at 7 psi) and heated at 35.degree. C. for 0.5 
hr. The mixture was cooled to 0.degree. C. and the top layer was analyzed 
by GC: 0.1% H.sub.2 O, 6.6% Me.sub.3 SiOH, 93.3% Me.sub.3 SiOSiMe.sub.3. 
Layers were separated, and the bottom layer was subjected to distillation 
to remove a small amount of siloxane. Obtained a total of 6.32 g (90.5% 
recovery) hexamethyldisiloxane after treating the product with a trace of 
TsOH. The aqueous layer was treated with calcium hydroxide (3.19 g, 43.1 
mmol), stirred for 18 hr, and filtered. The basic filtrate was used as 
reagent for another charge of trimethylfluorosilane as described above. 
The reaction was monitored by GC. When the composition remained constant 
(ca. 6% TMSF), an additional charge of KOH (0.335 g) was added and the 
pressurized mixture was stirred for 18 hr at 45.degree. C. The quantity of 
isolated hexamethyldisiloxane was 6.11 g. 
EXAMPLE 39 
A 3-n rbf fitted with a reflux condenser and a N.sub.2 purge inlet was 
charged with diphenyl sulfone (0.6 g, 2.75 mmol). CF.sub.3 CF.sub.2 
CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (4.02 g, 10 mmol) was added in 
one portion. The mixture was heated in an oil bath at 160.degree. C. There 
was obtained 1.4 mL (@ 0.degree. C.) after 1.5 hr. .sup.19 F NMR features 
PPVE and TMSF as major products, although the PPVE/C.sub.3 F.sub.7 
OCHFCF.sub.3 ratio was 65/35. A number of unidentified byproducts were 
also present. 
EXAMPLE 40 
A mixture of CF.sub.3 CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 
(4.0 g), Cs.sub.2 CO.sub.3 (50 mg), and diphenyl suflone (100 mg) was 
placed in a 3-n rbf (fitted with a reflux condenser and connected to a gas 
trap) and heated in an oil bath at 170.degree. C. There was obtained 2.44 
g of colorless volatiles which consisted of a 44.4/1.2/54.4 (mol %) 
mixture of PPVE/C.sub.3 F.sub.7 CHFCF.sub.3 /TMSF by .sup.19 F NMR. GC 
analysis showed two peaks with an area ratio 67.7/32.3 (PPVE/TMSF). 
EXAMPLE 41 
Fluorine chemical shifts are reported in ppm from CFCl.sub.3. Spectra were 
recorded on a Nicolet NT200 spectrometer at 188.2 MHz. Solvents with 
minimum water concentrations are required for reliable results in the NMR 
experiments described herein. Ether and THF were distilled from 
sodium-benzophenone and then stored over activated sieves. All reactions 
were carried out in an atmosphere of dry nitrogen, and manipulations and 
sample preparations were carried out in a Vacuum Atmospheres drybox. 
Typical substrate concentrations were ca. 0.1 to 0.2M. 
The spectrum of the mixture of CF.sub.3 CF.sub.2 CF.sub.2 
OCF(CF.sub.3)CO.sub.2 K (92 mg, 0.25 mmol) and CF.sub.3 CF.sub.2 CF.sub.2 
OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 (100 mg, 0.25 mmol) in THF-d.sub.8 showed 
a single set of signals for the fluorocarbon framework: -80.53 and -85.12 
(AB pattern, J=142 Hz, OCF.sub.2), -81.39 (t, J=7.2 Hz, CF.sub.3) -82.24 
(d, J=1.9 Hz, CF.sub.3), -128.2 (bd s, CF), -129.82 (s, CF.sub.2). This 
spectrum exhibits simple averaged shifts for the corresponding segments of 
the two components. Spectral parameters for the separate components are 
given for comparison: [R.sub.f CO.sub.2 K: -81.7 and -84.0 (AB pattern), 
-81.33 (t, J=7.2), -82.2 (d, J=2.3), -125.6 (m, CF), -129.9 (s); R.sub.f 
CO.sub.2 SiMe.sub.3 : -79.41 and -86.18 (AB pattern, J=152), -81.37 (t, 
J=7.1), -82.24 (d, J=1.5), -129.71 (s), and -130.38 (d, J=18.9); R.sub.f 
CO.sub.2 TAS: -81.3 and -83.2 (AB pattern, J=146), -81.22 (t, J=6.8), 
-81.40 (d, J=1.7), -122.9 (m), -129.76 (s).] 
For simplest analysis in other reactions reported here, examination of the 
shift for the CF group is the most informative. The spectrum of a similar 
mixture, prepared by reaction of the anhydride and one equivalent of 
potassium trimethyl silanolate, was temperature-invariant to -80.degree. 
C., demonstrating the facility of the trimethylsilyl exchange process. 
Chemical shifts of the CF resonance for representative mixtures of CF.sub.3 
CF.sub.2 CF.sub.2 OCF(CF.sub.3)CO.sub.2 SiMe.sub.3 /desilylation reagent 
(1.00/0.20 mol ratio) are given in the table below. In all these cases, 
the "desilyation reagent" is only slightly soluble in THF-d.sub.8, but 
dissolves and reacts upon addition of the TMS ester. Shifts for the 
R.sub.f CO.sub.2.sup.- are dependent upon counterion. 
______________________________________ 
desilylation reagent 
chem. shift of CF 
______________________________________ 
Et4N.sup.+ CN.sup.- 
-128.8 
CF.sub.3 CO.sub.2 K 
-129.4 
TAS d-10-camphorsulfinate 
-129.04 [TAS = tris(di- 
methylamino)sulfonium] 
______________________________________ 
A short discussion of the effects of chemical exchange on NMR spectra may 
be found in R. K. Harris, "Nuclear Magnetic Resonsance Spectroscopy", 
Pittman Publishing Inc., 1983, Chap. 5.