Process for the preparation of fluorine-containing ketones

Perfluorocarboxylic acid salts of a monovalent metal are reacted with perfluorocarboxylic acid fluorides in aprotic polar solvents. Perfluoroketones are obtained. The salt of the perfluorocarboxylic acid can be replaced by alkali metal salts of formic acid, oxalic acid or of oxygen-containing mineral acids, the central atom of which is an element of the groups IIIA to VIIA of the periodic table and which mineral acid is weaker than trifluoroacetic acid. The same result is obtained if the anhydride of the perfluorocarboxylic acid is contacted with an alkali metal fluoride. The synthesized perfluoroketones are liquids of high chemical and thermal stability.

The present invention relates to a process for the preparation of 
perfluoroketones from perfluorocarboxylic acid fluorides. 
It is known from U.S. Pat. No. 3,185,734 to convert highly fluorinated acid 
fluorides into fluorinated ketones with hexafluoropropene or 
perfluoroisobutylene at a temperature of from 50 to 250.degree. C., in an 
autoclave, in the presence of fluoride ions. This process is 
advantageously carried out in polar solvents, for example acetonitrile. It 
seems however, that this reaction cannot be applied to other 
perfluorinated olefins of low molecular weight. Moreover, frequently 
perfluoronated olefins are not accessible. This process, consequently, has 
only a narrow application field. 
There was therefore a need for a process that should be substantially more 
variable with regard to the feed products than the process of U.S. Pat. 
No. 3,185,734: a process that should be performed without using 
perfluoroolefins and that should yield perfluorinated organic ketones, 
especially those having a high boiling point. 
A process has now been found for the preparation of aliphatic 
perfluoroketones, which comprises reacting a perfluorocarboxylic acid salt 
of the formula 
EQU R.sub.1 -CO.sub.2 M II 
wherein 
R.sub.1 represents a perfluoroalkyl radical having of from 2 to 50 carbon 
atoms, which may contain one or more ether oxygen linkages and 
M is a metal selected from the group consisting of Li, Na, K, Rb; Cs and 
Ag, 
With perfluorocarboxylic acid fluorides of the formula 
EQU R.sub.2 - COF III 
wherein 
R.sup.2 is a perfluoroalkyl radical having of from 1 to 50 carbon atoms 
which may contain in addition one or more ether oxygen linkages, 
In an aprotic solvent, at a temperature of from 20 to 200.degree. C. 
The reaction temperature is in the range of from 50 to 180.degree. C., in 
particular of from 100 to 150.degree. C. The pressure applied is not 
critical. However, the solvent should be present in a liquid state at the 
chosen reaction temperature. 
The quantity of solvent is not critical. It generally ranges between 10 and 
200% of the volume of the acid fluoride used. 
The aliphatic perfluorinated ketones obtained correspond to the formula 
EQU R'.sub.1 -- CO -- R.sub.2 I 
wherein R.sub.1 ' is a perfluoroalkyl radical having of from 2 to 50 carbon 
atoms which contain in addition one or more ether oxygen linkages, and 
R.sub.2 is defined as indicated above. 
Frequently, R.sub.1 ' is identical with R.sub.1. This is the case for 
example when using salts wherein R.sub.1 represents the groups C.sub.2 
F.sub.5 --, (CF.sub.3).sub.2 CF-- and C.sub.3 F.sub.7 OCF(CF.sub.3)--. In 
other cases R.sub.1 ' is isomeric with R.sub.1. This is the case for 
example when using salts wherein R.sub.1 represents the groups CF.sub.3 
(CF.sub.2).sub.2 -- and CF.sub.3 (CF.sub.2).sub.3 --. Generally a 
secondary radical R.sub.1 ' is formed from a primary radical R.sub.1 
thereby. 
The reaction according to the invention takes place according to the 
following equation: 
EQU R.sub.1 --C(O)--OM + F--C(O)--R.sub.2 .fwdarw. R.sub.1 '--C(O)--R.sub.2 + 
CO.sub.2 + MF 
Ii iii i 
the radicals R.sub.1 and R.sub.2 may be linear, branched and/or cyclic. If 
these radicals contain oxygen atoms in ether groups, preference is given 
to those containing of from 3 to 25, in particular of from 5 to 20 carbon 
atoms. This is especially applicable to R.sub.1. 
Among perfluoroalkyl radicals free from oxygen preference is given to those 
which contain at least 2, preferably of from 3 to 8, carbon atoms. This is 
especially applicable to R.sub.1. 
The number of oxygen atoms in ether linkages which may be present in each 
of the radicals R.sub.1 and R.sub.2 may, for example, be half the number 
of the carbon atoms of the radical (the radical of the polymer of 
perfluoroethylene epoxide) or about one third (the radical of the polymer 
of perfluoropropene epoxide). 
Suitable compounds of the formula III are those containing the structural 
element F-C-C-CO-F, especially in the form of --CF.sub.2 CF.sub.2 COF or 
--CF(CF.sub.3)COF, the free valencies being saturated by fluorine, 
perfluoroalkyl or perfluoroalkoxy radicals. The latter radicals may 
additionally contain one or several oxygen atoms as ether groups. 
As examples of R.sub.1 and R.sub.2 there may be mentioned: perfluoropropyl, 
perfluorobutyl, perfluoropentyl, perfluoroheptyl, perfluorononyl, 
perfluoro-1-methyl-2-oxa-propyl, perfluoro-1-methyl-2-oxa-butyl, 
perfluoro-1-methyl-2-oxa-pentyl, perfluoro-1,3-dimethyl-2-oxa-butyl, 
perfluoro-1,4-dimethyl-2,5-dioxaoctyl, perfluoro-1-methyl-2-oxa-hexyl, 
-heptyl, -octyl, perfluoro-1,4,7-trimethyl-2,5,8-trioxaundecyl as well as 
the radicals of the formula 
##STR1## 
wherein Y is an integer of from 0 to 5. 
A part of the compounds of the formulae II and III is known, the other part 
may be obtained according to known processes. For example, acid fluorides 
III having ether-like bound oxygen atoms may be prepared by reacting 
hexafluoropropene-epoxide with aliphatic, perfluorinated carboxylic acid 
fluorides (cf. U.S. Pat. Nos. 3,250,808; 3,321,532). The products thus 
obtained have the general formula 
##STR2## 
Especially appropriate for the process of the invention are acid fluorides 
of the formula IIIa, wherein the perfluorinated alkyl radical R.sub.f 
contains from 1 to 10, preferably 3 carbon atoms, and X represents an 
integer of from 1 to 6. 
The alkali metal salts of the corresponding perfluorocarboxylic acids may 
be prepared from the acid fluorides III and IIIa in simple and known 
manner, by reaction with aqueous alkali metal hydroxide or aqueous alkali 
metal carbonate. Alkali metal fluorides formed in the process do not 
detrimentally affect the further reaction. 
Suitable solvents for the process of the invention are aprotic polar 
solvents, for example amides, such as dimethylformamide or 
dimethylacetamide. Tetramethylurea and hexamethylphosphoric acid triamide 
may also be used. Preference is given to alkyl glycol ethers, for example 
dialkyl ether of glycol, of di-, tri- or tetra-ethylene glycol with alkyl 
groups having 1 or 2 carbon atoms. 
Especially appropriate are diethylene-glycol-dimethyl ether (diglyme) and 
tetraethylene-glycol-dimethyl ether (tetraglyme). 
The process of the invention is generally performed in the following 
manner: About equimolar quantities of both reaction components II and III 
are introduced into a reaction vessel together with the solvent and the 
mixture is stirred at the reaction temperature until completion of the 
reaction. 
The end of the reaction can be seen by the fact that CO.sub.2 is no longer 
evolved. When using an excess of the salt II, the end of the reaction can 
moreover be recognized by the fact that acid fluoride can no longer be 
detected by IR-spectroscopy (disappearance of the acid fluoride band at 
5.3 .mu. as in Example 6 below). However, it is advantageous to use an 
excess of acid fluoride for obtaining a quantitative conversion. 
The excess is suitably in the range of from 5 to 30%, in particular of from 
10 to 20%. The excess of acid fluoride can be separated from the ketone by 
distillation and recovered upon completion of the reaction. 
The process according to the invention may also be performed using acid 
fluorides of perfluorinated dicarboxylic acids. Acid fluorides of this 
type may be obtained inter alia according to German Offenlegungsschrift 
No. 2,451,493. Thus perfluorinated diketones are formed, since both acid 
fluoride groups react. 
The mixture consisting of salts of the formula II and of acid fluorides of 
the formula III may alternatively be prepared by mixing perfluorinated 
acid anhydrides with alkali metal fluoride (NaF, KF, RbF, CsF). Thereby an 
equilibrium is set up between the acid anhydride on the one hand and salt 
plus acid fluoride on the other hand. The fact that this equilibrium is 
indeed shifted towards the components salt/acid fluoride, can be seen in 
the course of the reaction between potassium fluoride and perfluoroacetic 
acid anhydride. In this process there are formed instantaneously potassium 
trifluoroacetate and trifluoroacetyl fluoride according to the equation: 
##STR3## 
In the next step perfluoroketone I is formed from II and III according to 
the invention. 
Like the synthesis of ketone from II and III the reaction of alkali metal 
fluoride with anhydride also takes place at a temperature of from 20 to 
200.degree. C., especially of from 50 to 180.degree. C., preferably of 
from 100 to 150.degree. C. The quantity of solvent is not critical either 
in this case. It generally ranges between 0.1 and 10, especially of from 
0.2 and 2, parts by volume per part by volume of acid anhydride. The end 
of the reaction can be observed by IR-spectroscopy or by the fact that the 
CO.sub.2 evolution is terminated. 
The molar ratio of alkali metal fluoride and acid anhydride is not 
critical. The reaction rate is increased by using higher amounts of alkali 
metal fluoride. As a general principle catalytic amounts of fluoride are 
sufficient, since, during the formation of the ketone, alkali metal 
fluoride is formed anew. Amounts of from 0.01 to 10, preferably of from 
0.1 to 5 and in particular of from 0.2 to 2 mols of alkali metal fluoride 
per mol of acid fluoride are suitable. 
A possible explanation of the reaction course is that from the alkali metal 
salt of the acids used and the acid fluoride there is first formed the 
anhydride, which decarboxylates in the presence of formed KF. 
Another possible explanation is that the perfluorocarboxylic acid salt II 
is first decarboxylated to give the vinyl compound which is then added to 
the acid fluoride III. 
The salts to be used according to the invention of the formula II may 
alternatively be prepared in situ from acid fluorides by the action of 
certain basic compounds. It has now been found that the ketone formation 
can likewise be caused by the action of alkali metal salts of formic or 
oxalic acid or of salts of mineral oxygen acids, the central atom of which 
is an element of groups IIIA to VIIA of the periodic table and which are 
weaker than trifluoroacetic acid, on perfluorocarboxylic acid fluorides of 
the formula R.sub.1 COF in an aprotic-polar solvent at a temperature of 
from 20 to 200.degree. C. 
Said salts convert the perfluorocarboxylic acid fluoride used into the 
alkali metal salt of the corresponding perfluorocarboxylic acid. The 
latter decarboxylates under the reaction conditions, probably while 
forming the corresponding perfluoroalkyl cation or perfluorovinyl ether. 
This intermediately formed compound reacts with a further molecule of 
perfluorocarboxylic acid fluoride in the presence of formed alkali metal 
fluoride to give the desired perfluoroalkylketone. 
Suitable for the process of the invention are the alkali metal salts of 
those mineral oxygen acids which are weaker than the acid from which the 
perfluorocarboxylic acid fluoride is derived. Since there are only small 
differences in the acid strength of the individual aliphatic 
perfluorocarboxylic acids, it will be sufficient to consider those mineral 
acids which are weaker than trifluoroacetic acid, i.e., the pK value of 
which is greater than 0.16 (the P.sub.K -value is defined as the negative 
logarithm of the dissociation constant of the acid in dilute aqueous 
solution). 
Especially appropriate are oxygen acids, the central atom of which belongs 
to the second line of the perodic table (elements 5 to 7 and 9) or to the 
third line (elements 13 to 17). It is especially suitable if the 
electronegativity of the central atom of the oxygen acid ranges between 
2.0 and 2.5. 
Suitable salts for the process of the invention are, for example, besides 
alkali metal salts of oxalic acid and of formic acid, the alkali metal 
salts of tetraboric acid (P.sub.K value 4.0), of metasilic acid (P.sub.K 
-value 9.7), of phosphorous acid (P.sub.K -value of 2.0), of sulfurous 
acid (P.sub.K -value 1.8) or of iodic acid (P.sub.K -value 0.77). Only the 
pK-value of the acid's first dissociation step is important. Formates, 
oxalates, tetraborates and metal silicates are used preferably. In 
particular, when reacting alkali carbonates with the acid fluorides 
mentioned at a temperature of from 20 to 200.degree. C. in aprotic-polar 
solvents, the corresponding alkali metal salts are formed. These salts, 
however, continue to react in most cases rapidly with acid fluoride 
according to the invention yielding the ketones I. This variant of the 
process according to the invention is represented by the following scheme: 
##STR4## 
If the free acid, from which the alkali metal salt used is derived, has a 
lower P.sub.K -value than the free acid from which perfluorocarboxylic 
acid fluoride is derived, the formation of the ketone can be observed, but 
very long reaction times and unsatisfactory yields are encountered. This 
is the case for sodium sulfate, for example, since sulfuric acid is a very 
strong acid (P.sub.K -value &lt; 10). 
Most suitable are therefore salts of those acids which have a P.sub.K 
-value in the range of from 0.16 to 10.0. The lower limit corresponds to 
the P.sub.K -value of trifluoroacetic acid, which may be considered as 
being representative for perfluorinated carboxylic acids with regard to 
the acid number. Acids which have a P.sub.K -value in the range of from 1 
to 10 are preferably used. Salt mixtures may also be used naturally. 
For forming a ketone molecule, one acid fluoride group generally requires 
one alkali metal ion. 
The conversion with the salts of a monobasic mineral acid (for example 
iodic acid) may be represented by the following equation: 
##STR5## 
When using salts of bivalent mineral oxygen acids, the reaction equation 
may be formulated as in the case of the alkali metal carbonates. 
The perfluorinated ketones I are substantially stable towards SF.sub.4 and 
UF.sub.6, especially if they have a higher molecular weight. They are not 
only inert towards acids and oxidants but also thermally stable. 
According to German Offenlegungsschrift No. 25 31 511 perfluorinated 
ketones containing ether groups may be decarbonylated in liquid phase, 
i.e., be converted into perfluorinated ethers, by photolysis with light 
having a wave length of from 180 to 600 nm. 
This process is also applicable to perfluoroketones free from ether groups, 
and in this case it yields perfluorinated hydrocarbons. Ther 
perfluoroderivatives prepared from the ketones I have in both cases a high 
resistance to chemicals, especially to bases. 
Depending on the chosen reaction components II and III, inert liquids I 
which have a boiling point in the range of from about 100 to 500.degree. 
C., may be prepared according to the invention. These liquids may be used 
as heat transferring agents if they have a low molecular weight and as 
lubricants, if they have a high molecular weight. 
It is an advantage of the process of the invention that it enables a 
homogenous final product to be prepared from homogenous starting materials 
even of high molecular weight. In contrast, in the known polymerization of 
hexafluoropropene epoxide or tetrafluoroethylene epoxide, a number of 
products having a different degree of polymerization is always obtained. 
This uniformity is desirable in most cases. 
This is the case, for example when using heat transferring agents for 
soldering processes. This process designated as "Condensation soldering" 
has been presented to the public in 1974 (R. C. Pfahl, J. C. Mollendorf, 
T. Y. Chu, NEPCON WEST, 1974). According to this process, a liquid having 
a high boiling point is heated to the boil. When an object is plunged into 
the saturated vapor, the latter condenses, whereby the object is rapidly 
heated to the boiling point of the liquid. The boiling point of the liquid 
is chosen so that the desired metal parts, for example the solder on 
printed circuit connections, melt. On the other hand, sensitive spots must 
not be damaged thermally. The liquid must be non-combustible, chemically 
and thermally inert, and non-toxic. 
Fluorinated polyoxypropylene (molar weight 950, boiling point 224.degree. 
C.), for example, has been proposed for junctions soldered with an alloy 
having a melting point of 183.degree. C. (60% of tin, 40% of lead). As 
mentioned above, ketones of the formula I may also be used for this 
process. By varying the radicals R.sub.1 ' and R.sub.2, the boiling point 
of the liquid may be adjusted to the melting point of the corresponding 
metal. 
If salts and acid fluorides having about the same molecular weight are used 
as starting compounds, a ketone having about the double molar weight will 
be obtained. This is also the case when high-molecular weight starting 
compounds are used, for example a polymeric hexafluoropropene epoxide. 
These polymers still possess a terminal acid fluoride group, which may be 
converted in known manner into the salt of the corresponding carboxylic 
acid. The salt obtained of the formula II may subsequently be reacted with 
further portions of the originally used acid fluoride according to the 
process of the invention. 
By reacting these high-molecular weight acid fluorides, which can be 
readily prepared from perfluorinated epoxide, with the analogous salts, 
perfluorinated ethers having a molecular weight of up to about 4500, may 
be prepared, ethers of a molecular weight of about 2000 being obtained in 
especially good yields. 
Suitable feed products of defined molecular weight are in particular the 
following oligomeric acid fluorides of the formula III (or the salts III 
which may be prepared from these fluorides): 
##STR6## 
wherein x is an integer of from 1 to 6, preferably of from 2 to 4, as well 
as 
##STR7## 
wherein y is an integer of from 0 to 5, preferably of from 1 to 3. 
The latter derivatives of dioxane wherein y is 0 or 1 may be readily 
prepared from hexafluoropropene epoxide according to the process disclosed 
in German Offenlegungsschrift No. 2,461,445). By further adding epoxide in 
the presence of cesium fluoride in aprotic polar solvents, the homologous 
compounds wherein y is an integer of from 3 to 5, may be prepared from 
these acid fluorides (cf. German Offenlegungsschrift No. 2 517 357). 
As has been mentioned above, the salts II may be prepared in situ by the 
action of certain basic compounds, for example alkali metal carbonates. 
The ketone synthesis thus modified is also carried out especially 
advantageously at a temperature of from 50 to 180.degree. C., especially 
of from 70 to 180.degree. C., preferably of from 100 to 150.degree. C. 
Suitable carbonates are the corresponding compounds of lithium, sodium, 
potassium, rubidium and cesium. Mixtures of these carbonates may also be 
used. 
The process according to the invention is generally performed in the 
following manner: About 1 equivalent of perfluorocarboxylic acid fluoride 
per equivalent of alkali metal salt is added to a suspension of the alkali 
metal salt of the mineral acid or of oxalic or formic acid, in an aprotic 
polar solvent, at a temperature of from 20 to 200.degree. C., preferably 
of from 50 to 180.degree. C. 
When using carbonates, generally the double molar quantity of acid fluoride 
is added to a suspension of the alkali metal carbonate in an aprotic polar 
solvent at a temperature of from 20 to 200.degree. C., in accordance with 
the reaction equation. The quantity of alkali metal salt is not critical 
and may be in the range of from 0.1 to 10 mols per mol of acid fluoride. 
An excess of alkali metal carbonate, for example of from 100 to 200 mol %, 
may be used. 
When using less reactive acid fluorides, i.e. compounds containing 2 or 
more ether groups, for example those of the formula IIIa wherein x is &gt; 1, 
the quantity of the alkali metal salt is not very critical. In this case, 
an excess of up to 100% of the theoretical quantity of the alkali metal 
salt may be used. 
A particular variant of the process comprises the use of an excess of the 
acid fluoride. It has been ascertained that perfluorovinyl ethers may be 
obtained as by-products, when using polymers of hexafluoropropane epoxide, 
especially polymers of an oligomerization degree of more than 5. These 
perfluorovinyl ethers react in the presence of formed alkali metal 
fluoride with the acid fluoride used in excess thus yielding the desired 
ketones. This reaction may be accelerated by the addition of CsF. 
When using reactive acid fluorides, i.e., compounds contain a small number 
of ether groups, for example perfluoroalkylpropionyl-fluorides and 
perfluoroalkoxypropionyl-fluorides (formula IIIa with x being 0), only the 
theoretically required quantity of alkali metal salt should be used, 
otherwise with an increasing amount of alkali metal salt, the quantity of 
formed perfluoroolefins would increase thus decreasing the amounof the 
desired perfluoroketone. The same applies for compounds of the formula 
IIIa with x being 1. Especially high yields are obtained, independent of 
the alkali metal salt used, if the process according to the invention is 
carried out under conditions which prevent the escaping of optionally 
formed small quantities of the perfluoro-vinyl compound from the reaction 
system. This may be achieved by operating in a closed vessel (autoclave) 
or by using a reflux condenser, or more simply by keeping the reaction 
temperature so low that the boiling temperature of the corresponding 
perfluorovinyl compounds is not attained. 
In first approximation, the boiling point of the vinyl compound is by 
5340:M (.degree. C.) lower than the boiling point of the corresponding 
perfluorocarboxylic acid fluoride (having the molecular weight M). 
In the process disclosed in U.S. Pat. No. 3,291,843 (Examples 13 to 17) 
only the perfluorovinyl ether, and not the perfluoroketone was obtained 
from alkali metal carbonate and perfluorocarboxylic acid fluoride. This 
different result is caused by the different feed quantity of alkali metal 
salt and by the different mode of operation (distilling off of the vinyl 
ether). 
The end of the reaction may be readily seen by the fact that the acid 
fluoride band has either completely disappeared in the infra-red spectrum 
at 5.3.mu. or, when using an acid fluoride excess, is no longer 
diminished. When using a carbonate, formate or sulfite, the end of the 
reaction may be seen by the fact that gases are evolved no longer. 
When working with an excess of acid fluoride in the range of from 5 to 30%, 
preferably of from 10 to 20%, acid fluoride which has not reacted may in 
most cases be distilled off from the ketone formed and be recovered owing 
to its lower boiling point. 
The quantity of solvent is not critical even when applying alkali metal 
salts of a mineral acid or of formic or oxalic acid. The quantity of 
solvent is generally in the range of from 0.1 to 10, in particular of from 
0.2 to 2 parts by volume per part of acid fluoride. 
The process will be illustrated in the following examples:

EXAMPLE 1 
Perfluoro-2,4-bis-(3',6'-dimethyl-1',4'-dioxan-2'-oxy)-pentanone-3 
In a three-necked agitator flask provided with a reflux condenser, a 
stirrer and a thermometer, 165 g (0.32 mol) of 
K-perfluoro[.alpha.-3,6-dimethyl-1,4-dioxanyl-2-oxy-propionate], 60 ml of 
tetraglyme and 165 g of 
perfluoro[.alpha.-(3,6-dimethyl-1,4-dioxanyl-2-oxy)-propionic acid 
fluoride] (0.34 mol) are stirred for 8 hours at 130.degree. C. The heavy 
phase of the reaction mixture is separated, washed with 100 ml of aceton 
and distilled. (Boiling point of from 219.degree. to 221.degree. C.). 
There are obtained 234 g (81.8% of the theory, calculated on potassium salt 
used) of the compound of the formula 
##STR8## 
the structure of which has been confirmed by analysis, and by infra-red, 
NMR and mass spectra. 
EXAMPLE 2 
Perfluoro-5,7-dimethyl-4,8-dioxa-undecanone-6 
A mixture of 140 g (0.37 mol) of K-perfluoropropoxypropionate, 92 g (0.277 
mol) of perfluoropropoxypropionic acid fluoride and 60 ml of tetraglyme is 
shaken for 24 hours at 130.degree. C. in a 500 ml autoclave. After cooling 
the pressure in the autoclave is released, the heavier phase which has 
been separated, is washed with 100 ml of acetonitrile and distilled. There 
are obtained 98.5 g (corresponding to 59.5% of the theory, calculated on 
acid fluoride used) of the compound of the formula 
##STR9## 
having a boiling point of from 140.degree. to 148.degree. C. 
EXAMPLE 3 
Perfluoro-5,8,11,16,19,22,25-octamethyl-4,7,10,13,17,20,23,26-octaoxa-nonac 
osanone-15 
70 g (0.081 mol) of a salt of the formula 
##STR10## 
(which has been prepared from pentameric hexafluoropropeneepoxide by 
saponification and neutralization with potassium hydroxide), 30 ml of 
tetraglyme and 51 g of the acid fluoride of the same perfluorocarboxylic 
acid are stirred in a glass flask for 8 hours at 130.degree. C. The 
product is shaken with 100 ml of acetonitrile and the lower phase is 
separated. The latter is diluted with 50 ml of trifluorotrichloroethane 
and the lighter phase which forms thereby is separated. From the lower 
phase there are obtained, after distillation of trifluorotrichloroethane, 
87 g of the ketone of the formula 
##STR11## 
which is pure, according to IR-spectroscopy. 
Further 7 g of the ketone precipitate from the separated tetraglyme phase, 
when the latter is diluted with 100 ml of water. The total yield of ketone 
is, consequently, 96.6% of the theory. The boiling point is in the range 
of from 175.degree. to 180.degree. C. 
EXAMPLE 4 
Perfluoro-[4-methyl-2-(3',6'-dimethyl-1',4'-dioxan-2'-yl-oxy)-nonanone-3] 
82.8 g of perfluorooctanoic acid (0.197 mol) are neutralized with a 20% 
aqueous KOH-solution to a pH of 6 and the salt mixture formed by octanoate 
and KF is dried for 24 hours at 100.degree. C./1 mbar. Thereafter 70 ml of 
tetraglyme are added. After addition of 100 g of 
perfluoro-(3,6-dimethyl-1,4-dioxanyl-2-oxy)-propionic acid fluoride, the 
mixture is stirred for 15 hours and the product mixture is treated as in 
Example 1. By distillation there are obtained 102 g (62.2% of the theory, 
calculated on used perfluorooctanoic acid) of the compound of the formula 
##STR12## 
having a boiling point of from 210.degree. to 222.degree. C., the 
structure of which is confirmed by the analysis and by spectroscopic data. 
EXAMPLE 5 
To 116 g of a carboxylic acid fluoride of a boiling point of from 
62.degree. to 104.degree. C. which has been prepared by polymerization of 
hexafluoropropene epoxide and of 96 g of the potassium salt prepared 
therefrom there are added 100 ml of tetraglyme and the mixture obtained is 
stirred at 130.degree. C. After 15 hours there are obtained 81 g of a 
ketone mixture having a boiling range of from 80.degree. to 140.degree. 
C./0.2 mbar, by distillation of the separated fluoro-organic phase, 
besides acid fluoride which has not reacted. This mixture is free from 
acid fluoride and in the IR-spectrum is show an C.dbd.O-absorption of the 
carbonyl ether group at 5.62.mu.. 
EXAMPLE 6 
To 53.4 g of perfluoro-K-n-propoxy-propoxypropionate (0.10 mol) of the 
formula 
##STR13## 
which are dissolved or suspended in 50 ml of tetraglyme there are added 
while stirring, at 50.degree. C., 47.6 g of 
perfluoro-(3,6-dimethyl-1,4-dioxanyl-2-oxy-propionic acid fluoride). After 
60 hours, about 80% of the acid fluoride have reacted according to the 
IR-spectrum. After 84 hours the acid fluoride band at 5.3.mu. has 
disappeared and the keto band at 5.6.mu. has appeared. The separated lower 
phase of the reaction mixture is washed with 50 ml of H.sub.2 O, is dried 
and distilled. 
There are obtained 71 g (78.2% of the theory) of a 
perfluoro-[2-(3',6'-dimethyl-1',4'-dioxan-2'-yl-oxy)-4,7-dimethyl-5,8-diox 
a-undecanone-3-] having a boiling point of from 210.degree. to 217.degree. 
C. 
##STR14## 
The structure is confirmed by the IR- and mass spectra and by the 
analysis. 
EXAMPLE 7 
Preparation of 
perfluoro-2,4-bis-(3',6'-dimethyl-1',4'-dioxa-2-oxy-)pentanone-3 with the 
use of the sodium salt 
The sodium salt prepared from 100 g (0.21 mol) of 
perfluoro-3,6-dimethyl-1,4-dioxanyl-2-oxy-propionic acid fluoride by 
saponification with H.sub.2 O and neutralization with aqueous NaOH is 
suspended in 60 ml of tetraglyme after drying at 100.degree. C./1 mbar. At 
100.degree. C. there are added dropwise while stirring 160 g (0.36 mol) of 
the above acid fluoride. After stirring for 5 hours at 130.degree. C. 
there are added to the product mixture after cooling 500 ml of 
acetonitrile and the forming heavier phase is separated together with the 
NaF formed. NaF is suction-filtered and the fluoro-organic phase is 
distilled. 
There are obtained 54 g of 
perfluoro-3,6-dimethyl-1,4-dioxanyl-2-oxy-propionic acid fluoride and 129 
g of ketone (boiling point of from 215.degree. to 221.degree. C.), 
corresponding to a yield of 69.4% of the theory. 
EXAMPLE 8 
To 56 g of the anhydride of 
perfluoro-.alpha.-[2-n-propoxypropoxy]-propionic acid of the formula 
##STR15## 
which have been prepared by dehydratation of the acid by means of P.sub.2 
O.sub.5, there are added 50 ml of tetraglyme and the mixture obtained is 
stirred for 7 hours at a temperature of 125.degree. C. in the presence of 
20 g of KF. The heavier phase which forms is separated and KF is filtered 
off. By distillation there are obtained 34 g of 
perfluoro-[bis-(5-methyl-3,6-dioxa-nonyl-2)-ketone] having a boiling range 
of from 216.degree. to 220.degree. C. (63.5% of the theory) and having the 
formula 
##STR16## 
EXAMPLE 9 
To 13 g of the silver salt of perfluorooctanoic acid (0.025 mol) and 10 ml 
of tetraethylene-glycol-dimethyl ether there are added 20 g of 
perfluoro-3,6-dimethyl-2,4-dioxanyl-2-oxy-propionic acid fluoride (0.042 
mol) and the resulting mixture is stirred for 20 hours at 110.degree. C. 
By distillation there are obtained 3.5 g (17%) of 
perfluoro-[4-methyl-2-(3',6'-dimethyl-1',4'-dioxan-2'-yl-oxy)-nonanone-3]. 
EXAMPLE 10 
Perfluoro-2,4-bis-(3',6'-dimethyl-1',4'-dioxanyl-2'-oxy)-pentanone-3 
In an agitator vessel, provided with a dropping funnel, a thermometer and a 
condenser, 300 g (0.63 mol) of 
perfluoro-.alpha.-perfluoro-.alpha.-(3,6-dimethyl-1,4-dioxanyl-2-oxy)-prop 
ionic acid fluoride are added at a temperature of 100.degree. C. to a 
suspension of 60 g of K.sub.2 CO.sub.3 (0.435 mol) in 200 ml of tetraglyme 
and the resulting mixture is stirred for 5 hours at 130.degree. C. 
Thereafter starting material is present no longer. After cooling, the 
formed heavier phase (230 g) is separated. To the upper solvent phase 
there are added 200 ml of H.sub.2 O. Thereby another 8 g of reaction 
product precipitate which are distilled with the main quantity of the 
reaction product. 
There are obtained 226 g (81% of the theory) of the compound of the formula 
##STR17## 
having a boiling point of from 216.degree. to 221.degree. C. 
EXAMPLE 11 
Perfluoro-di-(5-methyl-3,6-dioxa-nonyl-2)-ketone 
As described in Example 10 50 g (0.10 mol) of 
perfluoro-.alpha.-(2-n-propoxy-propoxy)-propionic acid fluoride are added 
dropwise to 10 g of K.sub.2 CO.sub.3 in 50 ml of tetraglyme at 130.degree. 
C. This mixture is stirred for 5 hours. After cooling, the heavier phase 
is separated, the upper phase is diluted with water as indicated in 
Example 10 and the precipitating fluoro-organic phase is distilled 
together with the main qunatity (36.5 g). 
There are obtained 31 g (66.7% of the theory of the compound 
##STR18## 
having a boiling range of from 60.degree. to 61.degree. C./0.3 mbar. 
EXAMPLE 12 
In analogous manner to Example 11, 10 g of Na.sub.2 CO.sub.3 are suspended 
in 30 ml of tetraglyme. 
Perfluoro-.alpha.-(3,6-dimethyl-1,4-dioxanyl-2-oxy)-propionic acid 
fluoride (50 g) is added thereto at 100.degree. C. and the resulting 
mixture is stirred at 130.degree. C. for 16 hours. 
After treating the reaction mixture there are obtained 39.5 g (84.8% of the 
theory) of the ketone of Example 10. 
EXAMPLE 13 
332 g of a hexafluoropropene-epoxide oligomer having a boiling range of 
from 220.degree. to 260.degree. C. and corresponding to the formula 
##STR19## 
are slowly added dropwise to a suspension of 60 g of K.sub.2 CO.sub.3 in 
200 ml of tetraglyme at 130.degree. C. and the resulting mixture is 
stirred for 2 hours at this temperature. To the product mixture there are 
added 200 ml of acetonitrile and the formed lower phase is removed. The 
potassium salt is filtered off, and the reaction product is distilled. 
There are obtained three fractions: 
1st fraction having a boiling range of from 45.degree. C./0.3 mbar to 
80.degree. C./0.4 mbar 
2nd fraction having a boiling range of from 80.degree. C./0.4 mbar to 
140.degree. C./0.4 mbar 
3rd fraction having a boiling range of from 140.degree. C./0.4 mbar to 
165.degree. C./0.4 mbar. 
The fraction (1) consists of oligomers having a terminal vinyl ether group 
(3). Fraction (3) consists, as it has been confirmed by IR-spectroscopy, 
of the desired ketone. The fraction (2) consists of the compounds (1) and 
(3) in a ratio of 1:1. 
EXAMPLE 14 
To 10 g of K.sub.2 CO.sub.3 (0.072 mol) and 3 g of CsF in 60 ml of 
tetraglyme placed in the same apparatus as in Example 10 there are added 
dropwise at 100.degree. C. 150 g (0.167 mol) of a hexafluoropropene 
epoxide oligomer having an average molecular weight of about 900 (boiling 
point of from 170.degree. to 300.degree. C.). Stirring is continued at the 
same temperature for 2 hours. 
After cooling to room temperature 20 ml of acetonitrile are added, the 
product mixture is shaken and the precipitating lower phase, which 
contains KF and tetraglyme, is distilled. After having distilled off 10 g 
of oligomer which has not reacted there are obtained 110 g of pure ketone 
having a boiling point of from 70.degree. to 140.degree. C./0.5 mbar, 
which corresponds to a yield of about 82%, calculated on reacted oligomer. 
EXAMPLE 15 
Example 11 is repeated but a reaction temperature of only 50.degree. C. is 
chosen. After a reaction time of 20 hours, the absorption band of the acid 
fluoride at 5.3.mu. has completely disappeared in favor of the keto band 
at 5.6.mu. according to the IR-spectroscopy. 
EXAMPLE 16 
Perfluoro-6-methyl-tetradecanone-7 
To a suspension of 50 ml of tetraglyme and 20 g of K.sub.2 CO.sub.2 placed 
in the agitator vessel of Example 10 there are added first 0.2 g of CsF 
and thereafter dropwise 100 g of perfluoro-octanoic acid fluoride, at a 
temperature of from 100.degree. to 110.degree. C. The product mixture is 
stirred for 60 hours at a temperature of from 100.degree. to 110.degree. 
C. The product mixture obtained is distilled. Besides 20 g of acid 
fluoride which has not reacted there are obtained 32 g of 
perfluoro-6-methyl-tetradecanone-7 having a boiling range of from 
210.degree. to 212.degree. C. The following structure is confirmed by the 
IR and mass spectra and by the elementary analysis: 
##STR20## 
EXAMPLE 17 
Perfluoro-2,4-bis-(3',6'-dimethyl-1,4-dioxan-2'-oxy)-pentanone-3 (ketone 1) 
from Na.sub.2 B.sub.4 O.sub.7 and 
perfluoro-[.alpha.-(3,6-dimethyl-1,4-dioxanyl-2-oxy)-propionic acid 
fluoride] (DOPF) 
50 g of DOPF (0.105 mol) are added to 20 g of anhydrous Na.sub.2 B.sub.4 
O.sub.7 (0.099 mol) which are placed in an apparatus provided with a 
stirrer, a thermometer, a condenser and a dropping funnel, at a 
temperature of 120.degree. C. and the product mixture is stirred at the 
same temperature for 46 hours. CO.sub.2 escapes in the course of the 
reaction. The product mixture is distilled and there are obtained 34.5 g 
of ketone 1 and 8.5 g of un-reacted acid fluoride. The yield, calculated 
on reacted acid fluoride, is 89.4%. 
##STR21## 
EXAMPLE 18 
As in example 17, 47.6 g of DOPF (0.1 mol) are added dropwise to a mixture 
of 10 g of K-oxalate (0.06 mol) and 30 ml of tetraglyme at 100.degree. C. 
and the product mixture is stirred for 4 hours at this temperature. By 
distilling the mixture, there are obtained 38 g of ketone 1, which 
corresponds to a yield of 86%. 
EXAMPLE 19 
To a suspension of 17 g of K-formiate (0.20 mol) in 60 ml of tetraglyme 
there are added 100 g of DOPF (0.21 mol) at 100.degree. C. and the mixture 
is stirred for 10 hours at this temperature. By distillation of the 
product mixture 56 g of ketone 1 may be isolated (60.1%). 
EXAMPLE 20 
Perfluoro-bis-(5-methyl-3,6-dioxa-nonyl-2)-ketone (ketone 2) from 
Na-m-silicate Na.sub.2 SiCO.sub.3 and 
perfluoro-.alpha.-(2-n-propoxy-propoxy-propionic acid fluoride 
To 20 g of Na.sub.2 SiO.sub.3 (0.164 mol) and 30 ml of tetraglyme there are 
added 50 g of the above acid fluoride (0.1 mol) at a temperature of 
110.degree. C. and the mixture is stirred for 4 and a half hours at this 
temperature. By distilling the mixture there are obtained besides 7 g of 
un-reacted acid fluoride 26 g of ketone, which corresponds to a yield of 
65.0%, calculated on reacted acid fluoride 
##STR22## 
EXAMPLE 21 
50 g of DOPF (0.105 mol) are added to 30 g of Na.sub.2 PO.sub.3 (0.207 mol) 
and 50 ml of tetraglyme at a temperature of 110.degree. C. and the mixture 
is stirred for 2 hours at this temperature. By distilling the mixture 
there are obtained 18 g (38.7%) of ketone 1. 
EXAMPLE 22 
Ketone 2 from perfluoro-.alpha.-(2-n-propoxy-propoxy)-propionic acid 
fluoride and K.sub.2 SO.sub.3 
48 g of the above acid fluoride (0.096 mol) are added to a suspension of 20 
g of K.sub.2 SO.sub.3 (0.126 mol) and 50 ml of tetraglyme at a temperature 
of 120.degree. C. and the mixture is stirred at 130.degree. C. for 74 
hours. By distillation there are obtained 14 g of ketone 2, which 
corresponds to a yield of 31.2%. 
EXAMPLE 23 
50 g of DOPF (0.105 mol) are added to 35 g of NaIO.sub.3 (0.176 mol) and 30 
ml of tetraglyme at a temperature of 110.degree. C. and the mixture is 
stirred at the same temperature for 2 hours. Distillation of the product 
mixture yields 5.5 g of ketone 1. 
EXAMPLE 24 
##STR23## 
50 g of a mixture of equal parts by weight of (HFPO).sub.4 and (HFPO).sub.5 
are added to 20 g of Na-tetraborate (0.099 mol) and 30 ml of tetraglyme 
and the mixture is stirred for 70 hours at 150.degree. C. Distillation of 
the mixtures yields 40 g of a ketone mixture having a boiling point of 
from 75.degree. to 110.degree. C./1 mbar.