GB2058763A

GB2058763A - Preparation of Fluorocarbonyl and Compounds

Info

Publication number: GB2058763A
Application number: GB8027961A
Authority: GB
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 1979-08-31
Filing date: 1980-08-29
Publication date: 1981-04-15
Also published as: JPS5640617A; DE3032471A1; IT1193981B; GB2058763B; DE3032471C2; IT8024382A0; JPS6145972B2; FR2464246A1; FR2464246B1

Abstract

Fluorinated carbonyl compounds are prepared by contacting a fluorinated methyl ether containing at least one methoxylated carbon atom- containing group selected from -CF2OCH3, =CFOCH3, <IMAGE> and <IMAGE> with a catalyst selected from SBX5, TaX5, NbX5, AsX5, BiX5TiX4, ZrX4, HfX4, AlX'G3, FeX3, mixtures of SbX3 and SbX5, ZM'X''6, and mixtures of ZM'X''6and M'X5 where X, independently, is F, Cl, Br or I, X', independently, is Cl, Br or I, and X'' is F or Cl, Z is H, NO, O2, alkali metal or NY4 where Y, independently, is H or alkyl of 1 to 6 carbon atoms, and M' is Sb or As at a temperature of -20 DEG to 200 DEG C.

Description

SPECIFICATION Preparation of Fluorocarbonyl Compounds Technical Field This invention relates to a catalytic process for preparing fluorine-containing carbonyl compounds from certain fluorinated ethers.

Background Art Preparation of methyl- and ethyl difluoro-(fluoroformyl)acetates ROOC--CF2,-COF (R=-CH3 or -02H5) by reacting the corresponding alkyl p-alkoxytetrafluoro-propionates with SO3 is known (England U.S. 4,131,740). Preparation of compounds ROOC(CF2)n~1COF and ROOC-A-COF by partial alcoholysis of, respectively, the lactone

(U.S. 4,127,731) where n is 2 to 4, the diacyl fluoride FOC-A-COF where A is a difunctional perfluorinated group of 1 to 10 carbon atoms (Japanese Application J53040708) is disclosed. England et al. (J.Fluorine Chem., 3, 69 [1973]) also disclose the reaction CF3CFHCF20CH3+SO3oCF3CFHCOF+CH30SO2F SbF5, SbCl5, SbF3, SbF3CI2, SbF2CI3, mixtures of HF and SbF5, SbCI5 or SbF3CI2, mixtures of SbF3 and SbCI5 or SbF3CI2, and TiF4 are known catalysts for fluorinating organic compounds; A. M. Lovelace et al. "Aliphatic Fluorine Compounds," Reinhold, p 2, 7-10 (1958). SbCl5, AlCl3,TiCl4 and SnCl4 are known Lewis acid catalysts for acylation reactions. Hexafluoro-antimonic acid (HSbFe) has been used for the protonation of olefins; G. A. Olah and Y. K. Mo, Advances in Fluorine Chemistry, 7, 69 (1973).

SbF5 is also disclosed as a catalyst for the formation of hexafluoroacetone from hexafluoropropene oxide; C. G. Krespan and W. J. Middleton, Fluorine Chemistry Reviews, 1, 147 (1967).

TaF5 and NbF5, in combination with HF, have been used as isomerization catalysts (U.S.

3,948,761).

Disclosure of Invention A process is provided for preparing fluorinated carbonyl compounds which comprises contacting a fluorinated methyl ether containing at least one methoxylated carbon atom-containing group selected from the group consisting of -CF2OCH3, =CFOCH3,

and

with catalyst selected from the group consisting of SbX3, TaX5, NbX5,AsX5, BiX5,TiX4, ZrX4, HfX4,AlX'3, FeX3, mixtures of SbX3 and SbX5, ZM'X"6, and mixtures of ZM'X"6 and M'X5 where M' is Sb or As; X, independently, is F, Cl, Br or I; X', independently, is Cl, Br or I; X" is F or CI; and Z is H, NO, 02, alkali metal or NY4 where Y, independently, is H or alkyl of 1 to 6 carbon atoms.

Preferred ethers in the practice of the present invention are drawn from those containing the above groups and include the following: Class 1. Saturated terminal ethers of the formula

wherein X1 is -H or -F, Y is -F or -CF3, r is O or 1, s is 1 or 2 such that r+s=2, and R' is -F, -Cl, -Br, -SO2F, -COF, -OCH3,-CN, -CO2H, -CO2CH3,-OC6F5, -OR, -SR, or -R where R is a fluorinated alkyl of 1 to 8 carbon atoms, linear or branched, interruptable with ether oxygen or keto groups, and optionally containing functional substituents selected from the group consisting of-F, -Cl, -Br, -SO2F, -COF, -OCH3,-CN, -CO2H, -CO2CH3, and -0C6F5.

Class 1 fluoroethers, in the practice of this invention, provide carbonyl compounds which are acid fluorides

Class 2. Saturated terminal ethers of the formula Zm(CFHCF2oCH3)2 where Z is --OO-, -S-, or (CF2)n where n is 1 to 8, and m is O or 1.

Class 2 fluoroethers provide acid fluorides

Class 3. Terminally unsaturated terminal ethers of the formula

wherein X2 and X3 are -H, -F, or-Cl, and R2 is perfluoroalkyl of 1 to 8 carbon atoms.

Class 3 fluoroethers provide acid fluorides

Class 4. Internally unsaturated terminal ethers of the formula

wherein R, R1 and R2 are as defined above.

These fluoroethers provide acid fluorides.

Class 5. Internally unsaturated terminal ethers of the formula

wherein R and R' are as defined above. These fluoroethers provide acid fluorides.

where R' is the same as R except that alkyl is alkylidene.

Class 6. Saturated internal ethers of the formula

wherein R and R1 are as defined above. These fluoroethers provide ketones.

Class 7. Unsaturated internal ethers of the formula

wherein X2, X3, R1 and R2 are as defined above. These fluoroethers provide ketones.

Fluoroethers which are operable in the present invention are numerous and include, but are not restricted to, mono- and polyethers of Classes 1 to 7. For example, the following additional classes of ethers containing the specified groups also provide carbonyl compounds when contacted with the catalysts of this invention.

In these formulae the symbols R1, R2 and s have the meaning defined above; R3, independently, has the same meaning as R2.

In the practice of the present invention, fluorinated ethers of Classes 1 to 7 defined above are contacted with a small (catalytic) quantity of a suitable catalyst listed above. The catalyst may be any one of the above catalysts or any mixture of two or more of the above catalysts. For example, mixtures of ZM'X"6 with M'X5 can contain 0 to about 100 moles of M'X5 per mole of ZM'X"6. Preferred components in such mixtures are HSbX"6 and SbX"5 where X" is F or Cl. Mixtures of SbX3 with SbX5 can contain about 0.01 to about 100 moles of SbX3 per mole of SbX5. Optionally, any of the catalysts listed above, particularly those which are liquid at ordinary temperatures, such as SbF5, SbCI5 and TiCI4, may be supported on an inert substrate such as graphite.

The contacting may be carried out over a wide range of temperatures from about -200C to about 2000C depending on the starting ether and catalyst. The preferred temperature is about -100 to about 1 500C. Especially preferred ethers methyl 2,2,3,3-tetrafluoro-3-methoxypropionate and 3methoxytetrafluoropropionitrile, both Class 1 ethers, are preferably contacted at about 600 to about 1 400C. Use of a solvent is optional; preferably a reaction product serves as a solvent. Freon E3, a commercial product having the formula F[CF(CF3)CF2O]3CHFCF3, and Rimar 101, a commercial mixture of perfluorinated alkyl furan and pyran are also suitable solvents.

The reaction may be carried out in a sealed tube or other closed container. The reaction product is isolated by distillation. Operation at atmospheric pressure is preferred, but reaction in closed vessels, in which an autogeneous pressure of up to 100 atmospheres may develop, is satisfactory.

In preparing fluorinated carbonyl compounds such as methyl difluoro(fluoroformyl)acetate (2) from a fluoroether of Class 1, it has previously been necessary to employ a stoichiometric amount of sulfur trioxide (SO3) which produced a corrosive and poisonous by-product, CH 3OSO2F. The process of the present invention requires only catalytic amounts of the catalyst compounds and mixtures described above, and the by-products CH3X or CH3X' are relatively inert and easily separated from the carbonyl product. Product yields in the present process are generally over 65%. Yields of over 95% 2 have been obtained by reacting methyl 2,2,3,3-tetrafluoro-3-methoxypropionate 1 in the presence of the catalysts of this invention (Example 2C).

Although it is in no way intended that the process of this invention be limited to any particular mechanism, it is believed that the conversion of fluoroethers of Classes 1 to 7 defined above to carbonyl compounds involves chemical interaction between said fluoroethers and catalyst in consequence of which said catalyst abstracts fluorine from the fluoroether. The following hypothetical equation involving a pentavalent metal chloride, for example, SbCl5, is illustrative: CF2OCH3+MCI5 ) COF+MCI4F+CH3CI The fluorinated specie MCI4F, in subsequent encounters with more fluoroether, may or may not become progressively more fluorinated; thus CF20CH3+MCI4F COF+MCI3F2+CH3CI, CF2OCH3+MCI3F2 ) COF+MCI2F3+CH3CI, etc.

and/or CF2OCH3+MCI4F > COF+MCI4F+CH3F may occur. Obviously, fully fluorinated compounds remain compositionally unchanged as in the final equation above; for example, CF2OCH3+MF5 ) COF+MF5+CH3F.

Although catalytic materials may be added in fully or partially fluorinated form, it may be preferable for economic reasons to introduce, as the starting catalyst, unfluorinated materials such as chlorides.

Materials suitable for introduction as catalysts in the practice of this invention include those broadly characterized as containing one or more species MXQS wherein M is a selected metal of valence y and Q is a selected radical of valence x, which can react with fluorinated ethers as illustrated above, e.g., x(-CF2OCH3) +MQx(-COF) +M 0 iFx+(CH3)xQ, and whose fluorinated reaction products can similarly react with fluoroether thus maintaining catalytic activity, as previously discussed.

Catalysts meeting the above description also include so-called complex acids and salts having the formula ZM'X"6 where the symbols are defined as above, e.g. NOM'X"6, O2M'X" H HM'X"6 and alkali metal, ammonium or quaternary ammonium salts of HM'X"6.

The active catalytic rrioiety within such complex compounds is believed to be M'X"5 or the M'X"6-anion. The complex compounds may be preferred because of improved solubility, viscosity and the like. Complex acids and salts of metal halides disclosed herein, other than those of Sb and As, are also expected to be suitable catalysts provided they and their more fluorinated products have some solubility in the reaction media.

Examples have been discovered wherein certain metal chlorides, namely SnCI4, WCI6, Mocks and GaCI3, while initially active in effecting the conversion of fluoroethers to carbonyl compounds, become less active, the conversion of ether becoming progressively more sluggish. It is believed that fluorinated derivatives of these metal chlorides produced in the reaction react more slowly with fluoroether, probably because of reduced solubility.

In a preferred embodiment of the present invention, HF is added to SbF5, in an amount up two a molar ratio of about 1:1, preferably 0.01:1 to 0.5:1. HF combines with SbF5 in equimolar amounts to form hexafluoroantimonic acid HSbF6, with the result that the viscosity of the normally viscous, polymeric liquid SbF5 is very substantially reduced without significant loss of catalytic activity. Mixtures of SbF5 and HSbFe, formed as just described, are considerably easier to transfer, for example, by pump or syringe, than pure SbF5.

In another preferred embodiment of the invention, graphite impregnated with SbX5 where X is as defined above, up to about 60% by weight, is used to catalyze the conversion of fluoroethers to fluorinated carbonyl compounds by allowing fluoroether vapor to contact said catalyst contained in a stirred-bed reactor.

Fluorinated ethers operable in the present invention are prepared by known methods including the addition of methanol to terminal and internal fluornolefins, unsaturated fluoroethers, and terminal diolefins; reaction of alkali metal alkoxides with fluoroolefins; and reaction of unsaturated fluoroethers with reagents such as COF2 to produce saturated, functional ethers, e.g.,

The fluorinated carbonyl compounds prepared in accordance with this invention are all useful.

The acid fluoride products of Class 1 to 5 ethers may be reacted with hexafluoropropane oxide (HFPO) by known methods (see, for example, Moore et al. U.S. 3,250,808) to form adducts, e.g.,

where n may be 1 to 6 and Rt, X1 and Y are as defined above. Said adducts may be converted to polymerizable vinyl ethers by pyrolysis, preferably in the presence of an alkali metal carbonate or phosphate:

Said vinyl ethers as well as the terminally unsaturated acid fluorides prepared from Class 3 and Class 7 ethers may be copolymerized with suitable ethylenically unsaturated olefins such as tetrafluoroethylene vinyl fluoride, vinylidene fluoride, hexafluoropropylene, perfl uoro(alkylvinyl)ethers, chlorotrifluoroethylene and the like.

Saturated ketones may be converted to acid fluorides by the action of HFPO in the presence of an alkali metal fluoride (Selman U.S. 3,274,239); e.g.,

and said acid fluorides may be converted to copolymerizable vinyl ethers by pyrolysis as described above.

The following examples illustrate the invention. All temperatures are in degrees Celsius. All parts and percentages are by weight unless otherwise specified.

Example 1

3-Methoxyperfluoropropionyl fluoride (1 178 g) prepared as shown above, and titanium tetrafluoride (189 g) were heated in a 2250 ml stainless steel cylinder at 1750 for 72 h. The cylinder was allowed to cool to room temperature and the volatile gases were transferred under a nitrogen atmosphere to a round bottomed flask immersed in a Dry ice-methanol bath and connected to a low temperature still. Gas evolved was characterized by infrared as methyl fluoride. There was distilled 111 g (77%j of perfluoromalonyl fluoride (II), b.p. --90.

Example 2

Methyl-2,2,3,3-tetrafluoro-3-methoxy-propionate (1, see D. W. Wiley, U.S. Patent 2,988,537; 21 g) and 1 g ofTiF4were sealed in a heavy-walled glass tube and heated in a steam bath overnight.

The tube was cooled in liquid nitrogen, opened and the contents vaporized and condensed into a still pot cooled in liquid nitrogen. Distillation in a low-temperature still gave 3.5 g of methyl fluoride (characterized by infrared and condensed into a frozen methanol trap) and 11.2 g (65%) of methyl difluoro(fluoroformyl)acetate (2).

The above experiment was repeated using 12.8 g of SbF5 as catalyst in place of the TiF4. There was isolated 2 g of CH3F and 13.1 g (76%) of 2.

E-3 is CF2CF2CF2OCF(CF3)CF2OCF(CF3)CF2OCF(CF3)H b.p. 1520 To 15 cc of E-3 oil under N2 in a still pot was added 2.5 g of SbF5 and then dropwise with stirring 23 g of 1. After a slight exotherm (380), the pot was heated and evolution of CH3F was vigorous at 600. There was distilled 16 g (84.7%) of 2. b.p. 820.

The reaction was run in a 1 00-ml 3-neck pot with thermometer and dropping funnel and attached to an 1 8" spinning band still. A Dry Ice-acetone trap was attached to the still. The system was evacuated, flushed with nitrogen and 25 ml (34 g) of 2 added as solvent under nitrogen to the still pot, followed by 1.6 g of antimony pentafluoride.

The product 2 was then heated to reflux (820) and 1 was added through the dropping funnel.

There was immediate evolution of methyl fluoride and 1 was added at about the same rate as 2 was collected from the still.

in about 2 h after adding 430.9 g of 5, the temperature in the pot rose to 1300 indicating that the catalyst was no longer active and 1 began to appear in the distillate. There was recovered 61.1 g of 1 and 333 g of 2, including 18 g which had been carried into the Dry Ice trap by the methyl fluoride evolved.

Therefore, 369.8 g of 1 was converted by 1.6 g of SbF5 to 299 g of 2 (allowing for 34 g charged to pot). The yield was 98.5%;

To 4 g of SbF5 in graphite (46%, from Alpha Division of Ventron Corporation) under nitrogen in a still pot was added 35 g of 1. The mixture was heated and methyl fluoride was evolved, beginning about 800. There was distilled 25.4 g (88.5%) of 2.

When less catalyst was used (70 g of 1 with 1 g of catalyst) the reaction went well but required a higher temperature (ca. 1120).

A stirred-bed reactor was used, consisting of a vertically mounted quartz tube 2.5 cm in diameter x46 cm long with a motor-driven stainless steel screw down the center. Two inlets at the top of the tube admitted a slow stream of nitrogen and a 50 ml hypodermic syringe driven by a Sage pump. The tube was heated by a split-type electric furnace. Off-gases were passed through the Dry Ice-acetone cooled traps. The tube was packed with 46 g of SbF5 in graphite (46% from the Alpha Division of Ventron Corporation).

From 59 g of 1 (b.p. 1350) passed over the stirred bed at 1 500, there was obtained, by distillation of material collected in the traps, 31 g (64.6%) of 2 (b.p. 820) and a residue of 4.5 g. The residue contained CF2(COOCH3)2 characterized by gas chromatography.

Hexafluoroantimonic acid (HSbF6) was prepared by cooling in an ice bath 37.15 g (0.171 m) of antimony pentafluoride (SbF5) in a plastic bottle, adding 3.48 g (0.174 m) of hydrogen fluoride (HF) and mixing well.

A 100-ml 3-neck flask was fitted with a thermometer, dropping funnel and a 1 5-cm unpacked still head with water condenser and an ice-cooled receiver. The system was evacuated, flushed with nitrogen and about 50 ml (67 g) of 2 was added to the flask, followed by 0.89 g of hexafluoroantimonic acid.

The solution was then heated to reflux and 1 was added dropwise at about the same rate as was distilled into the receiver. The initial pot temperature dropped from 870 to 800'and then rose slowly until addition of 1(211.5 g total) was stopped at a pot temperature of 1040. Distillation ceased when a pot residue of 5.5 g remained (contained CF2(COOCH3)2) and 236 g had been collected in the receiver. By gas chromatographic analysis the distillate was 96.8% 2 and 3.2% 1. Therefore the yield, allowing for recovered 1 (7.5 g) and 67 g of 2 used as solvent, was 161.4 g of 2 (96.4%).

Pure antimony pentafluoride is a viscous polymeric liquid, very difficult to transfer, e.g., by hypodermic syringe. When mixed with hydrogen fluoride, even in small amounts, HSbF6 is formed and polymeric chains are destroyed decreasing viscosity. Antimony pentafluoride, HSbF6, and their mixtures are equivalent in catalytic activity for the above reaction. In addition to the pure compounds, catalytic quantities from three 1000-9 batches of SbFs containing respectively 5, 20 and 25 g of hydrogen fluoride to reduce viscosity have been Used successfully.

(G) Using the apparatus described in part 2(F) 2.5 g of TiF4 was charged to the still pot followed by 66 g of 1. On heating and stirring, methyl fluoride was evolved and 2 collected from the still.

Heating was continued until only a small residue remained in the still pot which was then cooled and 24 more grams of 1 added. After this conversion another 65-g charge of 1 was added to the residue in the still and the reaction continued. A total of 1 55 9 of 1 was converted to 108 g (85%) of 2 from the initial 2.5 9 of titanium tetrafluoride charged.

A mixture of 0.62 9 of TaF5 (tantalum pentafluoride) and 89 9 of 1 was stirred and heated in a 100-ml 3-neck flask attached to a spinning band still and fitted with a thermometer and magnetic stirrer. Methyl fluoride began coming off around 1000, and the contents of the flask refluxed at 1100, while 2 was collected at a head temperature of 7080 depending on the rate of methyl fluoride evolution. A total of 65 9 (87%) of 2 was collected and then 7 g of CF2(CO2CH3)2 (methyl difluoromalonate) was distilled under vacuum.

Maximum pot temperature was 1500. After cooling the pot, an additional 81 g of j was added to the residue without more catalyst. Heating to 1300 caused methyl fluoride evolution and 2 was collected as above. The yield of pure 2 was 58.5 9 (88%) along with 8 9 of CF2(COOCH3)2.

A total of 170 9 of 1 was converted (0.36% catalyst requirement by weight).

A mixture of 68.6 9 of 1 and 0.67 9 of SbCl5 in a still pot when heated to about 1000 began to evolve methyl fluoride gas and the temperature began to drop. The mixture was then refluxed at about 880 while 2 was distilled off at a slow rate.

There was recovered 49.5 9 (87.9%) of 2 and 4.5 9 of CF2(COOCH3)2.

A mixture of 1.38 9 of SbCl5, 1 9 of SbF3 and 5 ml (8 9) of @ was sealed in a glass tube. Methyl fluoride was evolved at room temperature and after heating 2.5 hours on a steam bath the product analyzed by gas chromatography 74% (4.9 9) 2, 0% 1 and 26% CF2(COOCH3)2.

(K)-(R) Additional catalysts were used in the conversion of methyl 2,2,3,3-tetrafluoro-3-methoxypropionate () to methyl difluoro(fluoroformyl)acetate (2) using a reaction system essentially as described in Example 2C. The catalysts, their amounts, the amounts of reactants employed and products recovered, the reaction temperature and time are tabulated below: Catalyst Reaction Wt. 1 2 Temp. Time Ex.Cmpd. (gJ (g) (9) % (0C) (h) 2K ZrCI4 1.0 67.8 49.0 88 120-135 6 2L NbFs 1.79 676.5 544.7 98 92-130 10 2M AsF5 7.0 185.2 138.6 91 85 1 2N AIC13 0.97 68.3 51.3 91.5 120 3 20 HfCl4 1.0 71.3 52.7 90 120 6 2P TaCl5 1.23 69.2 51.3 90 120 1 2Q TiCI4 1.0 68.0 54.0 97 115-125 0.5 2R FeCI3 6.7 61.5 35.0 96 135 6 2S Nbl5 1.1 69.7 56.6 99 135 0.5 2T NbBr5 2.7 67.0 53.1 96.5 120 0.5 2U All3 8.7 61.5 47.2 93.5 125 1 2V AlBr3 1.95 70.3 55.2 96 130 3 2W TiBr4 4.0 64.5 49.8 94 98 0.5 2X NOSbF6 1.0 67.8 > 53.0 > 95 70-100 0.5 Example 3

The reaction of the kinetic dimer of hexafluoropropene ((CF3)2CFCF=CFCF3) with sodium methoxide in methanol is reported to give predominantly 1 ,3,4-trimethoxy-2-trifluoromethyl- 1 ,3,4,5,5,5-hexafluoro-1 -pentane (N. Ishikawa and A. Nagashima, Bull. Chem. Soc. Japan, 49 (2), 504 (1976)).

To 14.5 g of antimony pentafluoride in a still pot under nitrogen was added slowly 75 g of the trimethoxy compound prepared as described in the above reference. Methyl fluoride was evolved and the product was distilled, b.p. mostly 3275 /55 mm. This material was then cooled, mixed with an additional 5.5 g of SbF5 and redistilled. There was obtained 24.5 g of the above methoxy diketone, b.p.

910/60 mm, refractive index n325=1.3648. Infrared 5.40,u and 5.95,u (C=O). The proton and fluorine magnetic resonance were consistent with the above structure, and elemental analysis agreed with the formula C,H3F,03.

Example 4

cis and trans isomers of each The above equilibrium mixture of dimethoxy derivatives was prepared by the reaction of the hexafluoropropene dimer, (CF3)2C=CFC2F5, with sodium methoxide in methanol, as described by N.

Ishikawa and A. Nagashima, Bull. Chem. Soc. Japan, 49 (2), 505 (1976).

The isomeric mixture (73 g) was added to 4.4 g of SbF5 in a still pot under nitrogen and heated.

Methyl fluoride was evolved and there was distilled 42.9 g (66.6%) of the above acylketene, b.p.8S 810.

Example 5

The above methyl ether 1(34 g) was added to 2.3 g of TiF4 in a still pot and the mixture heated.

Methyl fluoride was evolved and there was distilled 26.3 g which was largely the acid fluoride, ll, above, b.p. 1030. Structure II was confirmed by IR (5.36ju COF, 5.99cm C=C) and nuclear magnetic resonance, and elemental analysis was consistent with the formula C,H3Fg06.

Part of the above product (19.6 g) was recharged to the still pot with 2.5 g of TiF4 and reheated.

More methyl fluoride was evolved and 15.7 g of product distilled mostly at 790 and was characterized by infrared as the acylketene Ill above.

Example 6

The above ether (77 g), prepared by bubbling perfluoroisobutene into methanol, was placed in a 100-ml 3-neck flask attached to a spinning band still and fitted with a thermometer and dropping funnel. A Dry Ice-acetone trap was attached to the still. After cooling the ether to --400, 2.23 g of SbF5 was added and the cooling bath removed. Reaction began (evolution of CH3F) below room temperature and considerable product was carried into the Dry Ice trap. When evolution of gas was complete the liquid in the trap was carefully transferred to the pot and distillation then gave 55.3 g of a- hydrohexafluoroisobutyroyl fluoride, b.p. 30--330.

Example 7

A 100-ml 3-neek flask was attached to a spinning band still, fitted with a thermometer and dropping funnel, evacuated and flushed with nitrogen. The above ether (38 g) was added, cooled with a Dry Ice-acetone bath-and then 1.0 g of SbF5 added. While coming to room temperature methyl fluoride was rapidly evolved. When evolution was complete, heat was applied to distill the above ketone, b.p.

600, 30 g (88%).

The flask was then cooled to room temperature and more ether (30.5 g) added dropwise through the funnel with stirring. Reaction (evolution of CH3F) was vigorous with the insoluble residue in the flask acting as catalyst. When gas evolution was complete, the pot was heated and 20 g of ketone collected. The pot was then cooled and the contents of the Dry Ice-acetone trap attached to the still added and distilled to give an additional 5 g of ketone. The total yield was therefore 57 g (92.7%).

Example 8

The above methyl ether (29 g) and antimony pentafluoride (2.4 g) were mixed cold in a still pot.

Gas (CH3F) was evolved at room temperature and 23 g of material collected in a Dry Ice-acetone vrap attached to the still. Redistillation of this material in a low temperature still gave 8.5 g (35.4%) of bis (trifluoromethyl)ketene, b.p. 50 and 9.0 g (37.5%) of perfluoromethacryloyl fluoride, b.p 520. The products were further characterized by infrared.

Example 9

The above methyl ether (20 g), prepared from hexafluoropropene and sodium methoxide, was cooled in a still pot with a Dry Ice-acetone bath and stirred while adding 2.8 g of SbF5. On warming, an exothermic reaction occurred (maximum temp. 300) and distillation gave 7.8 g, b.p. 70--850. The Dry Ice-acetone trap attached to the still collected 7.5 g of CF2=CFCOF (perfluoroacryloyl fluoride) (b.p.

250), characterized by infrared.

Example 10

Potassium fluoride (25 g) was vacuum dried in a 3-liter, 3-neck flask by heating with a hot-air gun under vacuum. After cooling and flushing with nitrogen, 64 g (2 m) of sulfur (vacuum dried) and 200 ml of purified dimethylformamide were added, the flask tared, evacuated, pressured with hexafluoro-propene (HFP) (maintained automatically at ca. 740 mm) and vigorously stirred. After heating to 750 to start the reaction, it was exothermic to 830. It was stopped while still reacting (856 g of HFP absorbed) and started again the next morning after adding 25 g of fresh catalyst. An additional 1 51 g of HFP was absorbed making a total of 1007 g (6.7 m). The mixture was then washed three times with water and then conc. H2SO4.There was obtained 707 g (75%) of I above (cis and trans isomers), b.p. 1301340.

A solution of 132 g of 85% KOH (2 m) in 500 ml of methanol was cooled to 300 and 250 g (0.5 m) of the vinyl sulfide I added slowly. When addition was complete, cooling was removed and stirring continued. The exothermic reaction was cooled as necessary to keep the temperature below 500. After stirring for an hour at room temperature, the mixture was poured into cold water, the heavy layer washed with water, dried and distilled. There was obtained 21 g (8.5%), b.p. 65-70V8.5 mm, largely II above.

A mixture (100 ml) of products from Part A containing product II was treated with 5 ml of SbF5 and rapidly distilled. This was repeated three times when distillation gave a fraction, 5.7 g, b.p. 1100 which was 90% III. IR; 5.70y (C=O) and 5.95y (C=C). Fluorine magnetic resonance was consistent with the structure Ill; elemental and mass spectrometric analysis were consistent with the formula C9F16SO.

Example 11

The above ether (32.5 g, prepared from the base-catalyzed addition of methanol to tetrafluoroethylene) in a still pot was cooled in a Dry Ice-acetone bath and 1.81 g of SbFs added. It was stirred on a still for 3 h with a Dry Ice-acetone trap attached while coming to room temperature.

All but the SbF5 had volatilized into the trap. Redistillation in a low temperature still gave 12.3 g of difluoroacetyl fluoride, b.p. ca. 00, characterized by infrared and 1 3.6 g of recovered starting material, b.p. 330.

Example 12

The above methyl ether (49.5 g, prepared from the reaction of hexafluoropropene with sodium methoxide in methanol) in a still pot was cooled in a Dry Ice-acetone bath and 2.70 g of SbF5 added.

The mixture was stirred on a still with a Dry Ice-acetone trap attached and the cooling bath removed.

Evolution of CH3F was vigorous below room temperature. The mixture was warmed until all of the product had collected in the Dry Ice-acetone trap. Material in the trap was redistilled in a lowtemperature still to give 33 g (82%) of 2,3,3,3-tetrafluoropropionyl-fluoride, b.p. 250.

Example 13

The above ether (1 5 g, a by-product of the reaction of hexafluoropropene with sodium methoxide in methanol) in a still pot was cooled in a Dry Ice-acetone bath and 2.52 g of SbF5 added. The mixture was stirred on a still with the cooling bath removed. Vigorous evolution of methyl fluoride began below 00. There was then distilled 8.2 g (84%) of the above diacid fluoride, b.p 720.

Example 14

To a stirred solution of 5% sodium methoxide in methanol was added gaseous perfluoroethyl vinyl ether with cooling (4050 ). The crude methyl ether product was water-washed and distilled, b.p. 700.

The above methyl ether (40 g) in a still pot was cooled in Dry Ice and 3.28 g of SbF5 added. The mixture was stirred and heated on a spinning band still with a Dry Ice-acetone trap attached. Evolution of methyl fluoride was vigorous at room temperature. The distillate and material in the Dry Ice-acetone bath was combined and redistilled in a low temperature still. There was collected 8.1 g (27%) of CF3CF2OCF2H, b.p. mostly --120 and 20.7 g (60%) of CF3CF2OCFHCOF, b.p. 50--52 . Structures were confirmed by proton and fluorine magnetic resonance.

Example 15

A mixture of 200 ml of methanol and 225 g of hexafluoropropene trimer isomer mixture (C9F18, see W. Brunskill, W. T. Flowers, R. Gregory and R. N. Hazeldine, Chem. Communications, 1444(1970)) of probable structure

and [(CF3)2CF]2C=CFCF3, II was stirred and cooled at -30 to --200 while adding dropwise a solution of 60 g of sodium methoxide in 400 ml of methanol. After coming to room temperature the mixture was poured into water, extracted with methylene chloride, and washed with dilute HCI. Distillation gave 176 g of methoxy derivative, b.p. 80--90 /40 mm, a mixture of at least two isomers (containing unsaturated methyl ether, C9FOCH3) by gas chromatography.The unsaturated methyl ether CgF170CH3 appears to arise from structure il above and is thought to have the structure

The above mixture (50 g) in a still pot was cooled in an ice bath and 5.16 g of antimony pentafluoride (SbF5) added. The mixture was heated on a still and vigorous evolution of methyl fluoride began at about 500. There was distilled 8.3 g of CgFtssO vinyl ketone boiling mostly at 1000 and 35 g of higher-boiling material which was retreated with 6.05 g of SbF5 and 10.4 g more of the C,Ft60 vinyl ketone distilled. The vinyl ketone absorbed at 5.60jt in the infrared.Elemental analysis was consistent with the formula C9F O. The vinyl ketone is believed to have the structure

Example 16

A solution of 140 g (0.74 mol) of methyl 3-methoxytetrafluoropropionate in 100 ml of ether was treated at 0 with 15.3 g (0.90 mol) of NH3. The resulting viscous mixture was stirred at 250 overnight and evaporated to dryness at 250 (10 mm). The crude residue was then recrystallized from ether/hexane to give 123.6 g (95%) of 3-methoxytetrafluoro-propionamide, mp 7880 . An analytical sample was recrystallized from ether/hexane, m.p. 83--850. IR (KBr): 2.95,3.02 and 3.10 (NH2), 3.37 and 3.49 (sat'd Cm). 5.92 (C=O), 6.19 (NH,), 7.5--14u (CF, C--O). NMR ((CD3)2(CO): 1H 6.67 (broad, 2H, NH2) and 3.66 ppm (s, 3H, OCH3): $9F120.6 (t, JFF 4.7 Hz, 2F, CF2) and -121.8 ppm (t, JFF 4.7 Hz, of d, JHFT 2.1 Hz, 2F, CF2). Elemental analysis was consistent with the formula C,H,F,NO,.

A solution of 52.5 g (0.30 mol) of the amide from Part A in 200 ml of diglyme was stirred at 100 while 47.5 g (0.60 mol) of pyridine and then 63.0 g (0.30 mol) of trifluoroacetic anhydride were added. The cooling bath was removed, and the mixture was stirred at ca 250 for 2 h. Evaporation of volatiles to 400 (4.5 mm) gave 42.7 g of crude product, which was distilled to afford 36.5 g (77%) of 3-methoxytetrafluoropropionitrile, b.p. 530. IR (neat): 3.36 and 3.48 (sat'd CH), 4.42 (CN), 8-1 0 (CF, C--O). NMR: 1H 3.78 ppm (s, OCH3): 19F -93.2 (t, JFF 6.3 Hz, 2F, CH2) and -108.8 ppm (t, JFF 6.3 Hz, 2F, CF2).Elemental analysis was consistent with the formula C4HsF4NO.

A mixture of 5.5 g of SbF5 and 22 g of 3-methoxytetrafluoropropionitrile prepared as in Part B was refluxed for 0.5 h in a 3-necked flask fitted with a dropping funnel, magnetic stirrer and water condenser to which a Dry Ice-cooled trap was attached. Only a very small amount of material collected in the trap. A total of 1 3.5 g SbF5 was then added to the refluxing pot through the dropping funnel.

Material collected in the Dry Ice trap was distilled to give 3 g (17%) of NC-CF2COF (2cyanodifluoroacetyl fluoride), b.p. approximately 00.

Example 17

A nitrogen-flushed, 300-ml, 3-neck pot with magnetic stirrer, thermometer, pressure-equalizing dropping funnel and 6-inch vigreux column topped by a Dry Ice-cooled trap and nitrogen bubbler was charged with 100 g of Rimar 101(30-35% perfluoro-2(n-butyl)furan, 55--60% perfluoro-2(n propyl)pyran, 5--159/0 unidentified perfluorinated compounds, product of Rimar SpA, Italy) solvent and 6 g of SbF5, stirred and heated to 950. 102.8 g of methyl-2-methoxytetrafluoropropionate was added slowly. Gas was evolved. The pot temperature was maintained at 8490 . The gaseous product was collected and identified by IR as largely methyl fluoride.

The residual liquid was cooled to room temperature and distilled through a 3-ft, Pt spinning band column. 11 9.3 g of a fraction boiling at 800 was collected and identified by gas chromatography and IR as an azeotrope of Rimar 101 and methyl 2-oxo-3,3,3-trifluoropropionate.

Best Mode Examples 2C, 2F, 21 and 2Q represent the best mode contemplated for carrying out the invention.

Industrial Applicability Class 1 to 5 are ethers the converted to fluorinated acid fluorides by the process of this invention.

Class 6 ethers are converted to ketones which may in turn be converted to acid fluorides by known methods. Said acid fluorides are intermediates to fluorinated vinyl ethers from which copolymers useful as stable oils, greases, elastomers and films may be prepared.

Ethers of Class 3 provide terminally unsaturated acid fluorides which may be copolymerized directly to useful fluoropolymers or converted to vinyl ethers; copolymers prepared from the latter contain terminal double bonds especially useful for curing said copolymers to durable elastomers or shaped articles. Class 4 and 5 ethers provide internal unsaturation which may be similarly utilized as cure sites in copolymers prepared from vinyl ethers derived from Class 4 and 5 ethers.

Ethers of Class 7, in the practice of this invention, provide terminally unsaturated ketones which may be copolymerized to fluorinated copolymers useful as stable oils, greases, elastomers and films.

Preferred ethers in the practice of this invention are of Class 1. Especially preferred are methyl 2,2,3,3-tetrafluoro-3-methoxypropionate (Example 2) and 3-methoxy tetrafluoropropionitrile (Example 16). Said ethers, respectively, provide methyl difluoro(fluoroformyl)acetate, an intermediate in the preparation of fluorinated vinyl ether copolymers which are especially useful as membranes in chloralkali electrolysis cells; and cyanodifluoroacetyl fluoride, an intermediate in the preparation of curable fluoroelastomers.

Claims

1. A method of preparing fluorinated carbonyl compounds which comprises contacting a fluorinated methyl ether containing at least one methoxylated carbon atom-containing group selected from the group consisting of -CF2OCH3, =CFOCH3,

with catalyst selected from the group consisting of SbXs, TaXs, NbXs, AsXs, BiX5, TiX4, ZrX4, HfX4, Air'3, FeX3, mixtures of SbX3 and SbX5,ZM'X"6, and mixtures of ZM'X"6 and M'X5 where M' is Sb or As: X, independently, is F, Cl, Br or I; X', independently, is Clj Br or I; X" is F or Cl; and Z is H, NO, 02, alkali metal or NY4 where Y, independently, is H or alkyl of 1 to 6 carbon atoms at a temperature of 200 to 200QC.

2. The method of Claim 1 in which the contacting is carried out at a temperature of10 to 1500C.

3. The method of Claim 1 or Claim 2 in which the catalyst is SbF5.

4. The method of Claim 1 or Claim 2 in which the catalyst is SbCl5.

5. The method of Claim 1 or Claim 2 in which the catalyst is a mixture of SbF5 and HSbF6.

6. The method of Claim 1 or Claim 2 in which the catalyst is TiCI4.

7. The method of any one of Claims 1 to 6 in which the fluorinated methyl ether is a saturated terminal ether of the formula

wherein X1 is-H or -F,Yis Y or -CF3, ris O or 1, s is 1 or 2 such that r+s=2, and R1 is -F, -Cl, -Br, -SO2F, -COF, -OCH3-CN, -CO2H, -CO2CH3,-0C6F5,-OR, -SR, or -R where R is a perfluorinated alkyl of 1 to 8 carbon atoms, linear or branched, interruptable with ether oxygen or keto groups, and which may contain functional substituents selected from the group consisting of-F, -Cl, -Br,-S02F, -COF,-OCH3,-CN, -CO2H, --CO,CH,, and --OC,F,.

8. The method of Claim 7 in which the fluorinated methyl ether is methyl 2,2,3,3-tetrafluoro-3methoxypropionate.

9. The method of Claim 7 in which the fluorinated methyl ether is 3-methoxy tetrafluoropropionitrile.

10. The method of Claim 7 in which the fluorinated methyl ether is an internally unsaturated terminal ether of the formula

wherein R1 is -F, -Cl, -Br, -SO2F, -COF, -OCH3, WCN, -CO2H, -CO2CH3,-0C6F5,-OR, -SR, or -R and R is a perfluorinated alkyl of 1 to 8 carbon atoms, linear or branched, interruptable with ether oxygen or keto groups, and which may contain functional substituents selected from the group consisting of -F, -Cl, -Br, -SO F -COF,-OCH3, -CN,-CO2H,-CO2CH3,a nd -OC6F5.

11. The method of Claim 7 in which the fluorinated methyl ether is an unsaturated internal ether of the formula

wherein X2 and X2 are -H, -F, or-Cl; R1 is -F, -Cl, -Br, -SO2F, -COF,-OCH3, -CN, -CO2H, 0zCH3,C6Fs,0R, -SR or -R where R is a perfluorinated alkyl of 1 to 8 carbon atoms, linear or branched, interruptable with ether oxygen or keto groups, and which may contain functional substituents selected from the group consisting of -F, -Cl, -Br, -SO2F, -COF, -OCH3,-CN, -CO2H, -CO2CH3,and --069F,; and R2 is a perfluoroalkyl of 1 to 8 carbon atoms.

12. A method of preparing a fluorinated carbonyl compound substantially as hereinbefore described in any one of the foregoing Examples.