HK1072595A - Process for preparing hydrofluoroethers - Google Patents

Description

Process for preparing hydrofluoroethers

Technical Field

The present invention relates to a catalytic process for the preparation of Hydrofluoroethers (HFEs) in high yield and high selectivity.

More particularly, the invention relates to compositions comprising an-O-R_hType end group hydrofluoroethers in which R is_hIs a saturated or unsaturated hydrocarbon group.

Background

Methods for preparing hydrofluoroethers are known in the art.

USP3962460 describes hydrofluoroethers and their synthesis. For example, the preparation of the compound CF by reacting dimethyl sulfate, potassium fluoride and a large excess of carbonyl reactant is described in this patent₃-CF(CF₃)-OCH₂Cl and the Compound CF₃-CF(CF₃)-OCH₃. The disadvantage of said method is that metal fluorides are used as reactants and that large amounts of reactants and inorganic salts formed during the reaction remain in the final mixture. These salts, such as potassium sulfate, must be handled. In addition, the yield of this process is not high.

Patent application WO97/38962 describes a process for preparing HFE in a dipolar aprotic solvent by reacting: a) (per) fluorocarbonyl compounds; b) fluorides, typically anhydrous metal fluorides, especially KF; c) tertiary or aromatic amines in an amount necessary to neutralize acidic contaminants, primarily HF, present in the reaction mixture; d) optionally a phase transfer catalyst. The mixture thus obtained is then added to an alkylating agent, such as methyl sulfate, to give the hydrofluoroether. The disadvantage of this process is that the amount of metal fluoride used is at least equal to the stoichiometric amount of acyl fluoride to be alkylated. And high yields are only obtained when a tertiary or aromatic amine is used in the presence of an excess of alkylating agent. Furthermore, as described in the previous patents, the mixture at the end of the reaction contains a large amount of reactants and inorganic salts to be disposed of.

Patent application WO99/37598 describes a process for preparing hydrofluoroethers by reacting fluoroalcoholates and alkyl fluorovinyl ethers in a dipolar aprotic solvent. The disadvantage of this process is that both reactants have to be prepared. Fluoroalkoxylates are obtained by reaction of acyl fluorides with an excess of anhydrous metal fluoride, such as KF, in an anhydrous environment. Alkyl fluorovinyl ethers are prepared by two steps of reacting an alcohol with a fluoroolefin and then dehydrofluorinating the resulting compound. The disadvantage of the described synthetic fluoroalkoxylate process is the use of large amounts of anhydrous metal fluoride per mole of acyl fluoride. A disadvantage of the process for the synthesis of alkyl fluorovinyl ethers is the use of fluoroolefins, which are not always available and tend to be toxic.

Patent application WO99/47480 describes a process for preparing hydrofluoroethers in which Lewis acid catalysts, such as SbF₅In the presence of a perfluorocarbon compound and an alkylating agent R¹-F reaction. A disadvantage of this process is that the catalyst is easily deactivated by impurities and reaction by-products in the starting product, for example when R is¹-F is CH₃CH₂Ethylene at-F, or residual water in contaminated alkaline compounds. Furthermore, it is necessary to prepare a monofluoroalkylating agent. Carbonyl fluoride and R in the presence of an acid catalyst¹The reaction of alkylation between the F alkylating agents is an exothermic equilibrium reaction. Only when using an absolute excess of alkylating agent R for the carbonyl compound¹Good yields only for-F. Further, as described above, since the reaction is an equilibrium reaction, the catalyst also promotes a reverse condensation reaction, and thus the crude reaction product is difficult to separate from the catalyst phase. According to the examples of this patent application, starting from a perfluorocarbon compound and an alkylating agent, only when CH is present₃The yield of hydrofluoroether is high when F is used as the alkylating agent.

It was therefore felt the need to obtain a preparation having one-O-R_hProcess for preparing terminal hydrofluoroethers wherein R_hIs a saturated or unsaturated hydrocarbon radical, the process having the following combination of characteristics:

high condensation yield, even when R is_hThe same is true when it contains one or more carbon atoms;

-possibility of catalyst recovery;

-separating the hydrofluoroether condensation product with simple techniques;

the by-products to be treated have a low environmental impact.

The applicant has surprisingly and unexpectedly found a process for the preparation of hydrofluoroether compounds which solves the above technical problems.

Disclosure of Invention

The object of the present invention is to provide a process for obtaining hydrofluoroethers of formula (I):

A-(R_f)_n0-CF(R_f1)-O-R_h (I)

wherein n0 is 0 or 1;

R_fis a divalent group: c₁-C₂₀Preferably C₂-C₁₂A linear or branched (per) fluoroalkylene group, optionally containing one or more oxygen atoms; or

CFWO-(R_f2) -CFW-, wherein W and W', which are identical or different, are fluorine, CF₃；R_f2Is a (per) fluoropolyoxyalkylene radical containing one or more units (C) statistically distributed along the chain₃F₆O); - (CFWO), wherein W is as defined above; (C)₂F₄O)，(CF₂(CF₂)_zCF₂) Wherein z is an integer 1 or 2; (CH)₂CF₂CF₂)；R_f1Is fluorine or C₁-C₁₀Linear or branched (per) fluoroalkyl or (per) fluoroalkoxyalkyl; r_hIs C₁-C₂₀Preferably C₁-C₁₀Straight-chain, branched-chain (possible)If applicable), saturated or unsaturated (if applicable) alkyl; or R_hIs C₇-C₂₀Alkylaryl, optionally containing a heteroatom selected from F, O, N, S, P, Cl; and/or are preferably selected from-SO₂F，-CH＝CH₂，-CH₂CH＝CH₂And NO₂A functional group of (a);

a is fluorine, (R)_h2O)-CF(R_f4) -, - (O) F, wherein

-R_h2And R_hIdentical or different, having R_hThe meaning of (a);

-R_f4and R_f1Identical or different, having R_f1The meaning of (a);

wherein a mono-or bifunctional carbonyl compound of formula (IV) is reacted with at least one equivalent of a fluoroformate of formula (III) in the presence of an ionic fluoride compound used as a catalyst and a liquid dipolar aprotic organic compound which is inert under the reaction conditions:

B-R_f-C(O)R_f1 (IV)

wherein B is F or-C (O) R_f4，R_f，R_f1And R_f4As defined above, the above-mentioned,

R-OC(O)F (III)

wherein R is R as defined above_hOr R_h2。

Detailed description of the preferred embodiments

R_fIn R_f2Is (C)₃F₆O) units may be (CF)₂CF(CF₃) O) or (CF)₃)CF₂O)。

For equivalent amounts of-C (O) R_f1or-C (O) R_f4In the case of a composite material, for example,the reaction between the carbonyl compound (IV) and the fluoroformate (III) produces one mole of carbon dioxide.

When the compound (IV) is difunctional, i.e. B ═ CO) R_f4When the carbonyl compound is reacted with two fluoroformates (III) having different R.

Preferably in formula (I), R_f1And R in A_f4Independently of one another is F, CF₃。

Preferably when R is_fWhen it is (per) fluoroalkylene, R_fSelected from the following groups: -CF₂-，-CF₂CF₂-，-CF₂CF₂CF₂-，-CF₂(CF₃) CF-; when R is_fWhen containing an oxygen atom, R_fpreferably-CF₂CF(OCF₃)-。

R_f2Is a perfluoropolyoxyalkylene chain having a number average molecular weight of 66 to 12000, preferably 100-.

Preferably R_f2The perfluoroalkoxyalkylene chain of (a) is selected from the following structures:

a)-(CF₂CF₂O)_m(CF₂O)_n(CF₂CF(CF₃)O)_p(CF(CF₃)O)_q-；

b)-(CF₂O)_n(CF₂CF(CF₃)O)_p(CF(CF₃)O)_q-；

c)-(CF₂CF₂O)_m(CF₂O)_n；

wherein:

m is 0 to 100, inclusive;

n is 0 to 50 inclusive;

p is 0 to 100, inclusive;

q is 0 to 60 inclusive;

m + n + p + q > 0 and R_f2The number average molecular weight of (b) is within the above-mentioned limit.

Preferably a perfluoroalkoxyalkylene group c), wherein the m/n ratio is from 0.1 to 10, n is not 0 and the number average molecular weight is within the above-mentioned limits.

Preferably R_hAnd R_h2Has the following meanings: -CH₃，-CH₂CH₃，-CH₂CH₂CH₃，-CH(CH₃)₂，-CH₂CH＝CH₂。

An ionic fluoride compound is any compound that is capable of generating ionic fluoride in the presence of a dipolar aprotic solvent at temperatures from 20 ℃ up to 200 ℃.

Examples of dipolar aprotic solvents are acetonitrile, dimethylformamide, glyme, polyoxyethylene dimethyl ether (PEO-dimethyl ether); tetraglyme and PEO-dimethylether having a number average molecular weight of 134-2000 are preferably used.

The ionic fluoride compound is preferably selected from metal fluorides, in particular alkali or alkaline earth metal fluorides; AgF; alkylammonium fluorides, alkylphosphonium fluorides in which the nitrogen or phosphorus atoms may be interrupted by one or more C's which may be identical or different from one another₁-C₈Alkyl substitution.

Preferred catalysts are CsF and KF.

Optionally the catalyst is supported on, for example, a porous material, e.g. Al₂O₃Or MgO.

The amount of catalyst used, expressed in mol%, with respect to the mono-or bifunctional carbonyl compound of formula (IV) is between 0.1% and 50%.

As mentioned above, the reaction between the carbonyl compound (IV) and the fluoroformate (III) takes place in the presence of a dipolar aprotic organic compound which is liquid and inert under the reaction conditions. Examples of such organic compounds are acetonitrile, dimethylformamide, glyme, polyoxyethylene dimethyl ether (PEO-dimethyl ether); tetraglyme and PEO-dimethylether having a number average molecular weight of 134-2000 are preferably used.

The weight ratio of the dipolar aprotic organic compound to the ionic fluoride compound is 1: 100-100: 1.

In the process of the present invention, optionally, tertiary amines and/or phase transfer catalysts may be used. These compounds have been found to favour the condensation reaction between (III) and (IV).

In the process of the present invention, the reaction temperature is 60 ℃ to 200 ℃, preferably 80 ℃ to 150 ℃.

The reaction pressure may be atmospheric pressure or higher, even up to 30 atm.

The formation of reaction products can be tracked, for example, by monitoring the pressure increase (formation of carbon dioxide) over time until the pressure remains constant.

The reaction time is from 1 to 100 hours, preferably from 6 to 72 hours.

When the carbonyl compound (IV) is a bifunctional compound, the reaction can also be carried out in two steps. In a first step, 1 mol of the fluoroformate (III) (R is R)_h) To a first equivalent of carbonyl compound (IV). At the end of the reaction, 1 mole of a different fluoroformate (R is R) is added_h2) To react with a second equivalent of carbonyl compound (IV). Alternatively, both fluoroformates may be added simultaneously.

The yield is expressed as the molar percentage of HFE obtained and of the initial carbonyl compound (IV).

The process of the invention enables high yields of HFE, typically higher than 70%, to be obtained.

Furthermore, the molar percentage of HFE and carbonyl compound (IV) already reacted is defined as the selectivity, which is generally higher than 90%.

At the end of the reaction, the condensation product is separated from the unreacted reactants by distillation or decantation. The most suitable method can be selected by the person skilled in the art according to the boiling point of the final product and of the dipolar aprotic compound used.

The suspension/solution of the ionic fluoride compound in the dipolar aprotic organic compound can thus be recovered and reused, even for multiple uses. One operation is to keep the catalyst suspension/solution in the polycondensation reactor: in this case, the reactants enter the reactor and only the condensation products, optionally unreacted compounds, are discharged.

The process of the present invention may be carried out in a batch mode or a continuous mode.

The carbonyl compound (IV) can be prepared according to the methods disclosed in the following patents: US3113967, US3114778, US3250808, US3351644, US6013795, US3847978, US6127498, US5488142, italian patent applications MI 2003 a 000018, MI 2003 a 000019 and MI 2002a 001365.

The fluoroformates (III) are known in the art and can be prepared according to the disclosure of patent GB 1216639.

The compounds prepared according to the present invention are useful as refrigerants, blowing agents, solvents, lubricants, heat exchange media and have reduced environmental impact.

The following examples are given to illustrate, but not to limit, the invention.

Example 1

(CF₃O)(CF₃)CFCF₂OCH₃Synthesis of (2)

0.36 g CsF powder (2.4 mmol and 2.02 g tetraglyme (CH)₃O(CH₂CH₂O)₄CH₃) A 25 ml autoclave equipped with a pressure transducer and a magnetic anchor was introduced through the drying oven. After removal of non-condensables by vacuum system, 23 mmol of acyl fluoride (CF) was condensed in the autoclave₃O)(CF₃) CFCOF and 23 mmole of methyl fluoroformate (CH)₃OC (O) F). The autoclave was placed in a constant temperature oil bath at 100 ℃. After 36 hoursThe heating was stopped and the contents of the autoclave were transferred to a vacuum system. 5.25 g of distillate were separated in a trap at-110 ℃ by trap-by-trap distillation using traps maintained at-110 ℃ and-196 ℃ respectively, and analyzed by GC to show that it contained 84 wt% of product (CF)₃O)(CF₃)CFCF₂OCH₃. The alkylation yield, which is expressed as the molar ratio of HFE obtained to carbonyl compound used, was 72%. The alkylation yield (selectivity) with respect to acyl fluoride was 95%.

Example 2

(CF₃O)(CF₃)CFCF₂OCH₂CH₃Synthesis of (2)

Except that 15 mmol of the same acyl fluoride and 15 mmol of ethyl fluorocarboxylate (CH) were fed₃CH₂OC (O) F) the procedure is as in example 1. After the trap-by-trap distillation, 3.21 g of a distillate containing 87% by weight of the desired product was separated, the alkylation yield was 76% and the selectivity was 96% with respect to the starting acyl fluoride.

Example 3

(CF₃O)(CF₃)CFCF₂OCH₂CH＝CH₂Synthesis of (2)

Except that 15 mmol of the same acyl fluoride and 15 mmol of allyl fluorocarboxylate (CH) were fed₂＝CHCH₂OC (O) F) the procedure is as in example 1. After the trap-by-trap distillation, 3.76 g of a distillate containing 95% by weight of the desired product was separated, the alkylation yield was 81% and the selectivity was 97% with respect to the starting acyl fluoride.

Example 4

(CF₃O)(CF₃)CFCF₂OCH(CH₃)₂Synthesis of (2)

Except for the feed of 15 mmoles of the same acyl fluoride, 15 mmoles of isopropyl fluoroformate ((CH)₃)₂CHOC(O)F) And the reaction time was 48 hours, the same procedure as in example 1 was conducted. After the trap-by-trap distillation, 4.35 g of a distillate was separated which contained 59% by weight of the desired product and had an alkylation yield of 57% and a selectivity of 82% with respect to the starting acyl fluoride.

Example 5

CH₃O-CF₂CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₃Synthesis of (2)

0.77 g of CsF powder (5.1 mmol), 2.10 g of tetraglyme and 4.09 g of a diacyl fluoride F (O) CCF having a number average molecular weight MW (MN) of 620, an m/n ratio of 4.3, and a terminal functionality of 1.82(12 mmol of acyl fluoride end groups) of C (O) F₂O(CF₂CF₂O)_m-(CF₂O)_nCF₂C (O) F (IA) was introduced via a drying oven into a 25 ml autoclave equipped with a pressure sensor and a magnetic anchor.

At-196 ℃ and in a vacuum system (10)^-3Mbar), and 20 mmol of methyl fluorocarboxylate were condensed in the autoclave. The autoclave was placed in a constant temperature oil bath at 100 ℃. After 24 hours the heating was stopped and 2.0 g of methanol was condensed in the autoclave to esterify the unreacted acyl fluoride groups. Then removing gas phase (CO) in a vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the reaction yield was 90% and the selectivity was 100% with respect to the starting acyl fluoride.

Example 6

CH₃CH₂O-CF₂CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₂CH₃Synthesis of (2)

0.38 g CsF powder (2.5 mmol), 2.04 g tetraglyme and 4.02 g of example 5The diacyl fluoride (IA) was introduced through a dry box into a 25 ml autoclave equipped with a pressure transducer and magnetic anchor. At-196 ℃ and in a vacuum system (10)^-3Mbar) was removed and then 19 mmol of ethylfluorocarboxylate were condensed in the autoclave. The autoclave was placed in a constant temperature oil bath at 100 ℃. After 48 hours the temperature was raised to 130 ℃ and allowed to react for 24 hours, after which heating was stopped and 2.0 g of methanol were condensed in the autoclave. Then removing gas phase (CO) in a vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the alkylation yield was 96% and the selectivity was 100% with respect to the starting acyl fluoride.

Example 7

CH₂＝CHCH₂O-CF₂CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₂CH＝CH₂Synthesis of (2)

0.40 g of CsF powder (2.6 mmol), 2.03 g of tetraglyme, 4.04 g of the diacyl fluoride (IA) of example 5 and 2.05 g of allyl fluoroformate (19.7 mmol) were introduced via a drying oven into a 25 ml autoclave equipped with a pressure sensor and a magnetic anchor. At-196 ℃ and in a vacuum system (10)^-3Mbar) was removed and the autoclave was placed in a constant temperature oil bath at 100 ℃. After 24 hours the heating was stopped and 2.0 g of methanol were condensed in the autoclave. Then removing gas phase (CO) in a vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the alkylation yield was 90% and the selectivity was 100% with respect to the starting acyl fluoride.

Example 8

CF₃O-(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₃Synthesis of (2)

Will be 0.152 g of CsF powder (1.0 mmol), 1.0 g of tetraglyme and 2.36 g of a monoacyl fluoride CF with a number average molecular weight (MN) of 590, an m/n ratio of 4.45 and a C (O) F end group functionality of 1.0(4.0 mmol acyl fluoride end group)₃O-(CF₂CF₂O)_m(CF₂O)_nCF₂C (O) F (IB) was introduced into a 25 ml autoclave equipped with a pressure sensor and a magnetic anchor via a drying oven. At-196 ℃ and in a vacuum system (10)^-3Mbar) and then 8 mmol of methyl fluorocarboxylate were condensed in the autoclave. The autoclave was heated to 100 ℃ with an oil bath and maintained at this temperature for 48 hours. The reaction was followed by checking the internal pressure. At the end of the reaction, 1.0 g of methanol was condensed in the autoclave. Then removing gas phase (CO) by vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the alkylation yield was 97% and the selectivity was 100% with respect to the starting acyl fluoride.

By following the increase in pressure with the increase in reaction time during the reaction due to the formation of carbon dioxide, it was noted that the alkylation yield was already higher than 80% relative to the starting acyl fluoride after the first 8 hours of the reaction, indicating that the reaction gave the desired product in high yield also in a short time.

Example 9

CF₃O-(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₂CH₃Synthesis of (2)

The procedure is as in example 8 except that 8 mmol of ethylfluorocarboxylate are condensed in an autoclave. The autoclave was heated to 100 ℃ with an oil bath and maintained at this temperature for 48 hours. The reaction was followed by checking the internal pressure. At the end of the reaction, 1.0 g of methanol was condensed in the autoclave. Then removing gas phase (CO) by vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed alkylation with respect to the starting acyl fluorideThe yield was 82% and the selectivity was 100%.

Example 10

CF₃O-(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH(CH₃)₂Synthesis of (2)

The procedure is as in example 8 except that 8 mmol of isopropyl fluoroformate are condensed in an autoclave. The autoclave was heated to 100 ℃ with an oil bath and maintained at this temperature for 48 hours. The reaction was followed by checking the internal pressure. At the end of the reaction, 1.0 g of methanol was condensed in the autoclave. Then removing gas phase (CO) by vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the alkylation yield was 90% and the selectivity was 100% with respect to the starting acyl fluoride.

Example 11

CF₃O-(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₂CH＝CH₂Synthesis of (2)

The procedure is as in example 8 except that 8 mmol of allyl fluorocarboxylate are condensed in an autoclave. The autoclave was heated to 100 ℃ with an oil bath and maintained at this temperature for 48 hours. The reaction was followed by checking the internal pressure. At the end of the reaction, 1.0 g of methanol was condensed in the autoclave. Then removing gas phase (CO) by vacuum system₂HF), the fluorinated phase is recovered and washed with water. By using¹H-NMR and¹⁹F-NMR analysis showed that the alkylation yield was 98% and the selectivity was 100% with respect to the starting acyl fluoride.

The increase in reaction time due to the formation of carbon dioxide during the reaction by following the pressure was noted to be higher than 80% of the alkylation yield relative to the starting acyl fluoride after the first 8 hours of the reaction, indicating that the reaction gives the desired product in high yield also in a short time.

Example 12

(CH₃)₂CFOCH₃Synthesis of (2)

0.38 g of CsF powder (2.5 mmol), 1.02 g of tetraglyme were introduced via a drying oven into a 25 ml autoclave equipped with a pressure sensor and a magnetic anchor.

The non-condensables were removed by a vacuum system, and then 15.6 mmol of hexafluoroacetone and 16.7 mmol of methyl fluoroformate were condensed in the autoclave. The autoclave was placed in a constant temperature oil bath at 100 ℃. After 36 hours, the heating was stopped and the contents of the autoclave were transferred to a vacuum system. 2.84 g of pure product were isolated in a trap at-115 ℃ by trap-by-trap distillation maintained at-78 ℃, 115 ℃ and 196 ℃ respectively, with an alkylation yield of 91% and a selectivity of 100% with respect to the starting hexafluoroacetone.

Example 13

(CF₃O)(CF₃)CFCF₂OCH₃Synthesis of (2)

0.36 g CsF powder (2.4 mmol), 2.01 g tetraglyme were introduced via a drying oven into a 25 ml autoclave equipped with a magnetic anchor. The non-condensables were removed by a vacuum system, and then 10 mmol of acyl fluoride (CF) was condensed in the autoclave₃O)(CF₃) CFCOF and 15 mmole of methyl fluoroformate CF₃OC (O) F. The autoclave was placed in a constant temperature oil bath at 100 ℃. After 24 hours, the heating was stopped and the contents of the autoclave were transferred to a vacuum system. 2.88 g of crude product were isolated in a trap at-78 ℃ by trap-by-trap distillation maintained at-78 ℃, -110 ℃ and-196 ℃ respectively, and analyzed by GC to show that it contained 93 wt% of the product (CF)₃O)(CF₃)CFCF₂OCH₃The alkylation yield relative to the starting acyl fluoride is 100%.

Example 14

(CF₃)₂CFCF₂OCH₃Synthesis of (2)

Except that 10.9 mmol of (CF) was fed₃)₂CFCOF and 17 mmole of methyl fluoroformate CF₃OC (O) F otherwise, the procedure is as in example 1. After the trap-by-trap distillation, 2.71 g of a distillate containing 72% by weight of the desired product was separated, the alkylation yield was 71% with respect to the starting acyl fluoride, and the selectivity was 95%.

Example 15

Synthesis of CH using KF as catalyst₃O-CF₂CF₂O(CF₂CF₂O)_m(CF₂O)_nCF₂CF₂-OCH₃

Example 5 was repeated except that KF (5.1 mmole) was used as the catalyst instead of CsF and heating was stopped after 48 hours.

The alkylation yield relative to the starting acyl fluoride was 85% and the selectivity was 100%.

Claims (18)

1. A process for preparing a hydrofluoroether of formula (I):

A-(R_f)_n0-CF(R_f1)-O-R_h (I)

wherein

n0 is 0 or 1;

R_fis a divalent group:

C₁-C₂₀preferably C₂-C₁₂A linear or branched (per) fluoroalkylene group, optionally containing one or more oxygen atoms;

-CFW′O-(R_f2) -CFW-, wherein W and W', which are identical or different, are fluorine, CF₃；R_f2Is a (per) fluoropolyoxyalkylene radical containing one or more units (C) statistically distributed along the chain₃F₆O); (CFWO), wherein W is as defined above; (C)₂F₄O)，(CF₂(CF₂)_zCF₂) Wherein z is an integer 1 or 2; (CH)₂CF₂CF₂)；R_f1Is fluorine or C₁-C₁₀Linear or branched (per) fluoroalkyl or (per) fluoroalkoxyalkyl;

R_his C₁-C₂₀Preferably C₁-C₁₀Linear, branched (if possible), saturated or unsaturated (if possible) alkyl; or C₇-C₂₀Alkylaryl, optionally containing a heteroatom selected from F, O, N, S, P, Cl; and/or are preferably selected from-SO₂F，-CH＝CH₂，-CH₂CH＝CH₂And NO₂A functional group of (a);

a is fluorine, (R)_h2O)-CF(R_f4) -, - (O) F, wherein

-R_h2And R_hIdentical or different, having R_hThe meaning of (a);

-R_f4and R_f1Identical or different, having R_f1The meaning of (a);

wherein a mono-or bifunctional carbonyl compound of the formula (IV) is reacted with at least one equivalent of a fluoroformate of the formula (III) in the presence of an ionic fluoride compound (catalyst) and a dipolar aprotic organic compound which is liquid and inert under the reaction conditions,

B-R_f-C(O)R_f1 (IV)

wherein B is F or-C (O) R_f4，R_f，R_f1And R_f4As defined above, the above-mentioned,

R-OC(O)F (III)

wherein R is R as defined above_hOr R_h2。

2. The method according to claim 1, wherein R_f2Is (C)₃F₆O) unit is (CF)₂CF(CF₃) O) or (CF)₃)CF₂O)。

3. The process according to claim 1 or 2, wherein in formula (I), R_f1And R in A_f4Independently of one another are F, CF₃。

4. A process according to any one of claims 1 to 3, wherein R is a group of formula (I)_fWhen it is (per) fluoroalkylene, R_fSelected from the following groups: -CF₂-，-CF₂CF₂-，-CF₂CF₂CF₂-，-CF₂(CF₃) CF-; when R is_fWhen containing an oxygen atom, R_fpreferably-CF₂(OCF₃)CF-。

5. A process according to any one of claims 1 to 3, wherein R is_f2Is a perfluoropolyoxyalkylene chain having a number average molecular weight of 66 to 12000, preferably 100-.

6. The method according to claim 5, wherein R_f2Is a perfluoroalkoxyalkylene chain, preferably selected from the following structures:

a)-(CF₂CF₂O)_m(CF₂O)_n(CF₂CF(CF₃)O)_p(CF(CF₃)O)_q-；

b)-(CF₂O)_n(CF₂CF(CF₃)O)_p(CF(CF₃)O)_q-；

c)-(CF₂CF₂O)_m(CF₂O)_n；

wherein:

m is 0 to 100, inclusive;

n is 0 to 50 inclusive;

p is 0 to 100, inclusive;

q is 0 to 60 inclusive;

m + n + p + q > 0 and R_f2The number average molecular weight of (b) is within the above-defined range.

7. The method according to claim 6, wherein R_f2Is a perfluoroalkoxyalkylene group c), wherein the ratio of m/n is from 0.1 to 10, n is not 0 and the number average molecular weight is within the above-defined range.

8. A process according to any one of claims 1 to 7, wherein in formula (I), R_hAnd R_h2Has the following meanings: -CH₃，-CH₂CH₃，-CH₂CH₂CH₃，-CH(CH₃)₂，-CH₂CH＝CH₂。

9. A process according to any one of claims 1 to 8, wherein the ionic fluoride compound is any compound capable of generating ionic fluoride at temperatures from 20 ℃ up to 200 ℃ in the presence of a dipolar aprotic solvent, such as acetonitrile, dimethylformamide, glyme, polyoxyethylene dimethyl ether (PEO-dimethyl ether).

10. The process according to claim 9, wherein the ionic fluoride compound is selected from metal fluorides, preferably alkali or alkaline earth metal fluorides; AgF; alkylammonium fluorides, alkylphosphonium fluorides in which the nitrogen and phosphorus atoms are each replaced by one or more C's which are identical or different from each other₁-C₈Alkyl substitution.

11. The method according to claim 9 or 10, wherein the ionic fluoride compound is CsF and KF.

12. A process according to any one of claims 9 to 11 wherein the catalyst is optionally supported.

13. A process according to any one of claims 1 to 12, wherein the amount of catalyst expressed in mole% with respect to the mono-or bifunctional carbonyl compound of formula (IV) is 0.1% to 50%.

14. The process according to any one of claims 1 to 13, wherein the dipolar aprotic organic compound which is liquid and inert under the reaction conditions is selected from acetonitrile, dimethylformamide, glyme, polyoxyethylene dimethyl ether (PEO-dimethyl ether); tetraglyme and PEO-dimethyl ether having a number average molecular weight of 134-2000 are preferably used.

15. The process according to any one of claims 1 to 14, wherein the weight ratio of the dipolar aprotic organic compound to the ionic fluoride compound is 1: 100 and 100: 1.

16. A process according to any one of claims 1 to 15, wherein a tertiary amine and/or a phase transfer catalyst is used.

17. A process according to any one of claims 1 to 16, wherein the reaction temperature of the process of the invention is from 60 ℃ to 200 ℃, preferably from 80 ℃ to 150 ℃.

18. A process according to any one of claims 1 to 17, carried out in a batch or continuous mode.