DE1283820B - Process for the production of perfluoro-alkyl-alkyl-ethers - Google Patents

Description

It is known (AG P ittm an u. DL Harp, Polymer Letters 3 PP, 379, 1965) that when hexafluoroacetone is reacted with potassium fluoride in an inert solvent, an addition compound is formed which is assigned the structure of potassium heptafluoroisopropylate . It is also known that this addition compound can be converted with epibromohydrin to form heptafluoroisopropyl glycidyl ether: The success of this reaction is due to activation of the bromine by the epoxy group. The introduction of other residues, for example the ethyl residue, did not succeed in this way.

There has now been a process for the preparation of unilaterally perfluorinated aliphatic ethers of the general formula (1) in which pure trifluoromethyl group or a fluorine atom, n an integer from 0 to 6, Ra a straight-chain or branched alkyl radical of 1 to about 18 carbon atoms, preferably 1 to 6 carbon atoms, which can be substituted, characterized in that perfluorocarbonyl compounds of general formula (2) in which Rf1 and n have the meanings given above, after the addition of (a) rubidium fluoride, cesium fluoride or a quaternary ammonium fluoride, or (b) potassium fluoride in the presence of catalytic amounts of a rubidium, cesium or quaternary ammonium salt in one with respect to the Reactant inert solvents with compounds of the general formula (3) X-R2 (3) in which R2 has the meaning given above and X is a chlorine, bromine or iodine atom or a sulfonic acid radical of the general formula (4) R3-SO2-0 - (4) in which R3 denotes an alkyl or alkoxy radical of 1 to about 4 carbon atoms or a phenyl or toluyl radical.

The radical R2 can, for example, be replaced by an alkyl - COO - CH2-, CH2 = CH - 0 - CO, cyano, carboxyl or carbalkoxy group or by a halogen atom, preferably a bromine atom, or by an alkoxy group, preferably a methoxy or Ethoxy group, may be substituted.

The products obtained are isolated in a manner known per se Way.

If the process is carried out with compounds of the general formula (3) mentioned, where R2 represents a β-halogenated alkyl radical, for example the β-bromoethyl group, the corresponding end products of the formula (1) can be converted into the corresponding perfluorinated vinyl ethers in a known manner by splitting off hydrogen halide the general formula be transferred.

The yields that can be achieved in accordance with the process are between 70 to 900 /, the theory. Process variant (b) is the preferred embodiment represent.

What the proportions of the process according to the implementation As far as reaction components are concerned, it is expedient to add 1 mole of perfluorocarbonyl compound of the general formula (2) with (a) at least 1 mol of rubidium, cesium or quaternary Ammonium fluoride or (b) at least 1 mole of potassium fluoride in the presence of 0.1 to 10 mole percent, preferably 1 to 10 mole percent, of a rubidium, cesium or quaternary Ammonium salt as a catalyst and the intermediate product formed in this way with 1 mol to implement the compound of the general formula (3). The mentioned alkali and Quaternary ammonium fluorides can be used in an excess, for example in a 1.1- up to 1. Smolar excess can be used. Also the connection of the mentioned general Formula (3) can be used in excess.

The addition of the above-mentioned fluorides is expedient at temperatures between about 60 and about +30 "C, preferably between about -40 and about + 20 ° C, the reaction of the intermediate products formed here with the compounds of the general formula (3) at temperatures between about 30 and about 130 ° C., preferably between about 40 and about 80 "C.

The reaction can be carried out in an autoclave.

The salts or salt-like compounds used as catalysts in process variant (b) consist of the large-volume rubidium, cesium or quaternary ammonium ions, the anions of which are, for example, chlorine, bromine or iodine ions or monoalkyl sulfate or monoalkyl sulfonate ions. Instead of the quaternary ammonium salts used as catalysts in process variant (b), it is also possible to use tertiary amines, for example trimethylamine, dimethylcyclohexylamine or "urotropein", preferably triethylamine, these amines prior to the actual reaction with the compounds of the general formula (3) mixed and, if necessary, by gentle heating into the corresponding quaternary ammonium compounds according to the equation be transferred.

The reaction temperatures are from about 0 to 150 ° C., preferably 20 to 100 "C.

Suitable solvents which are inert to the reactants are for example acetone, tetrahydrofuran, acetonitrile, preferably diglycol dimethyl ether, Dimethylformamide and dimethyl sulfoxide.

Instead of the perfluoroacyl fluorides falling under the general formula (2) as starting compounds, the corresponding perfiuoracyl chlorides of the general formula (5) can also be used in which n is an integer from 0 to 6, are used and reacted in an inert solvent with at least 2 moles of one of the fluorides mentioned and then in a reaction stage according to process variants (a) and (b) described above with compounds of the general formula (3) further to the process products of the general formula (1) mentioned, in which R: denotes a fluorine atom and n has the abovementioned meaning. The preferred embodiment, however, is the reaction of the perfluoroacyl compounds of the general formula (2).

The products manufactured according to the process represent narcotics as well Are intermediates for the production of polymers.

Example 1 61 g (0.40 mol) of cesium fluoride, which is in a stirrer, Cooler and gas inlet tube provided with reaction vessel are located through Two hours of heating to 160 "C at 0.2 Torr freed from moisture residues. Then 200 ml of diglycol dimethyl ether are added. and at 0 ° C 46.5 g (0.40 moles) of trifluoroacetyl fluoride initiated with stirring. The reaction mixture is kept at room temperature until formed stirred a slightly cloudy solution.

After adding 68 g (0.44 mol) of diethyl sulfate, the mixture is left overnight stand at room temperature and slowly warm to 60 "C, holds 3 hours at this Temperature and finally distills the end product from the thick reaction mixture away. The raw yield is 65 g. Fractional distillation gives 60 g of pentafluoroethyl ethyl ether from the boiling point of 26.5 to 27 "C, which corresponds to a yield of 91% of theory on the trifluoroacetyl fluoride used.

Example 2 61 g (0.40 mol) of cesium fluoride, which is in a stirrer, Refrigeration cooler and gas inlet pipe see reaction vessel are through Two hours of heating to 160 "C at 0.2 Torr freed from moisture residues. Then 200 ml of diglycol dimethyl ether are added and 46.5 g (0.40 mol) of trifluoroacetyl fluoride are added at 0 ° C initiated with stirring. The reaction mixture is kept at room temperature until formed stirred a slightly cloudy solution.

After adding 73.5 g (0.44 mol) of ethyl bromoacetate, the mixture is made up Heated to 50 "C and slowly increased to 80" C in the course of 8 hours. Then it will be with a further increase in temperature at 200 Torr, the reaction product together with distilled off part of the solvent. The distillate is made twice with water extracted, dried with sodium sulfate and distilled. 68 are formed g of ethyl pentafluoroethoxyacetate with a boiling point of 130 to 131 "C, which is a yield of 730 / o of theory, based on the trifluoroacetyl fluoride used.

Example 3 In one with stirrer, cold cooler and gas inlet pipe provided reaction vessel are 58 g (1 mol) potassium fluoride, 8 g (0.05 mol) cesium fluoride, 154 g (1 mol) of diethyl sulfate and 350 ml of diglycol dimethyl ether and adjusted to about 50 "C heated.

Then slowly, as the absorption takes place, 102 g Initiated (0.88 mol) of trifluoroacetyl fluoride. It is left at room temperature overnight stand, initially unconverted CF3COF (14 g) distills off and then drives off in a vacuum, the reaction product in traps cooled to -800 ° C. The fractional Distillation gives 93 g of pentafluoroethyl ethyl ether with a boiling point of 26.5 "C, which a yield of 750 / o of theory, based on converted trifluoroacetyl fluoride, is equivalent to.

Example 4 In a 0.5 l steel autoclave with magnetic stirring 58 g (1 mol) potassium fluoride, 8 g (0.08 mol) triethylamine, 126 g (1 mol) dimethyl sulfate and submitted 200 ml of diglycol dimethyl ether. After closing and evacuating the Autoclaves are 96 g (0.83 mol) of trifluoroacetyl fluoride at room temperature through a steel capillary initiated with stirring. Then 14 hours at a temperature of 55 "C and then the reaction product with a slow increase in temperature to 105" C distilled off at a pressure of 50 torr in traps cooled to -80 "C. The fractionated Distillation of the crude product gives 110 g of pentafluoroethyl methyl ether at the boiling point 4 to 6 "C, which corresponds to a yield of 890 /, of theory, based on the trifluoroacetyl fluoride used, is equivalent to.

Example 5 In a 0.5 l steel autoclave with magnetic stirring 58 g (1 mol) of potassium fluoride, 8 g (0.08 mol) of triethylamine, 167 g (1 mol) of ethyl bromoacetate and submitted 200 ml of diglycol dimethyl ether. After closing and evacuating the 50 g (0.43 mol) of trifluoroacetyl fluoride are placed in the autoclave at room temperature Stirring was initiated and the mixture was subsequently stirred at 60 to 70 ° C. for 18 hours. The reaction mixture is extracted with ice water, separated, dried with sodium sulfate and fractionally distilled. 72 g of ethyl pentafluorethoxyacetate are formed from boiling point 129 to 131 "C, which corresponds to a yield of 7S0 / o the theory, based on the trifluoroacetyl fluoride used.

Claims (5)

Claims: 1. Process for the production of unilaterally perfluorinated, aliphatic ethers of the general formula (1) in which pure trifluoromethyl group or a fluorine atom, n is an integer from 0 to 6 and R2 is a straight-chain or branched alkyl radical of 1 to 18 carbon atoms, preferably 1 to 6 carbon atoms, which can be substituted, characterized in that perfluorocarbonyl compounds of the general Formula (2) in which R, and n have the meanings given above, after addition (a) of rubidium fluoride, cesium fluoride or a quaternary ammonium fluoride, or (b) of potassium fluoride in the presence of catalytic amounts of a rubidium, cesium or quaternary ammonium salt in a related Solvents which are inert to the reactants with compounds of the general formula (3) X-R2 (3) in which R2 has the abovementioned meaning and X is a chlorine, bromine or iodine atom or a sulfonic acid radical of the general formula (4) R8-SO2-O - (4), in which R2 denotes an alkyl or alkoxy radical of 1 to about 4 carbon atoms or a phenyl or toluene radical. 2. Modification of the process for the production of unilaterally perfluorinated aliphatic ethers of the general formula (1) in which n is a number from 0 to 6 and R2 is a straight-chain or branched alkyl radical of 1 to about 18 carbon atoms, which can be substituted, according to claim 1, characterized in that perfluorocarbonyl compounds of the general formula (2) in which n is a number from 0 to 6, is reacted with at least 2 moles of potassium, rubidium, cesium or quaternary ammonium fluoride in a solvent inert to the reactants and the corresponding perfluoroacyl fluoride initially formed according to claim 1 into the unilaterally perfluorinated aliphatic ether of the aforementioned general formula (1) converted. 3. The method according to claim 1 or 2, characterized in that the reaction in acetone, diglycol dimethyl ether, tetrahydrofuran, acetonitrile, Performs dimethylformamide or dimethyl sulfoxide. 4. The method according to claim 1 (b), characterized in that one tertiary amines are used in catalytic amounts, these with the compounds of the general formula (3) mixed and by gentle heating in the as catalysts acting corresponding quaternary ammonium compounds transferred. 5. The method according to claim 1 to 4, characterized in that one those in the reaction with compounds of the formula (3), where R2 is a B-halogenated Represents alkyl radical, corresponding compounds obtained by splitting off Hydrogen halide converted into the corresponding perfluorinated vinyl ethers.