Hydrofluoroether composition and preparation method thereof

Abstract

Disclosed is a liquid composition comprising one or more compounds of formula (I): CFHX-CF2-O-R-O--CF2-CFHX (I), one or more compounds of formula (II): CFHX-CF2-O-R-OH (II) wherein: R in formulae (I) and (II) is independently selected from the group consisting of C2-C10 divalent linear or branched alkyl, optionally comprising a ring, an aromatic ring and / or an oxygen heteroatom involved in an ether linkage,-X is selected from the group consisting of halogen, H, Rf, optionally comprising a ring, an aromatic ring and / or an oxygen heteroatom involved in an ether linkage, wherein Rf is selected from:---a C1-C8 fully or partially fluorinated linear or branched alkyl group, optionally comprising a ring, or--C1-C3 fully or partially fluorinated alkoxy group, in formula (I), the case of two X is the same or different, preferably the same, and the case of two X is the same or different, preferably the same, or the case of two X is the same, preferably the same, or the case of two X is the same, preferably the same, or the case of two X is the same. -the amount of the one or more compounds of formula (II) is from 0.002% to 5% by weight of the one or more compounds of formula (I).

Description

Technical Field

[0001] The present invention relates to a hydrofluoroether composition which can be used as a solvent. The present invention also relates to a method for preparing the composition.

[0002] This application claims priority to European patent application filed in Europe on June 29, 2022 under number 22181823.0, the entire contents of which are incorporated herein by reference for all purposes. Background Art

[0003] Various methods for producing hydrofluoroethers from difunctional alcohols are known in the art. US 4208081 (DuPont) describes the preparation of hydrofluoroethers using ethylene glycol in diethyl ether solution and tetrafluoroethylene (TFE). However, the reaction is not complete, as two reaction products are formed in almost equal amounts, one in which both -OH groups of the ethylene glycol are converted into ether groups, and the other in which only one of the -OH groups of the ethylene glycol is converted into an ether, while the other remains a free hydroxyl group.

[0004] RU 1810324 to Natalya Guseva reports the preparation of hydrofluoroethers from the reaction between ethylene glycol and TFE in diglyme solvent in an anhydrous process with a yield of 78%.

[0005] Compared with the alternative materials available on the market, hydrofluoroether-based solvents are very advantageous because they have low GWP (global warming potential), low flammability and are therefore safe and easy to handle. However, hydrofluoroethers generally have relatively low polarity, which in some way limits their range of application. On the other hand, mixing hydrofluoroethers with other more polar solvents may cause the composition to be incompatible with certain materials. Therefore, there is a need for such solvent compositions, which have all the advantages of hydrofluoroether-based solvents (including the same material compatibility) and a wider range of applications in terms of the materials that these solvent compositions can dissolve. The composition of the present invention completely maintains all the characteristics of hydrofluoroether-based solvents, while having a fine-tuned increased polarity, so it has a wider range of applications as a solvent than the pure material, and simultaneously retains all the advantages of using a hydrofluoroether-based solvent.

[0006] Furthermore, there is a need for a composition that can be easily prepared using a simple and high yielding process. The present invention also relates to such a process. Summary of the invention

[0007] The present invention relates to a liquid composition comprising one or more compounds of formula (I):

[0008] CFHX-CF2-ORO-CF2-CFHX(I), and

[0009] One or more compounds of formula (II):

[0010] CFHX-CF2-OR-OH(II)

[0011] in:

[0012] - R in formula (I) and (II) is independently selected from C2-C10 divalent linear or branched alkyl groups, which may optionally contain rings, aromatic rings and / or oxygen heteroatoms participating in ether bonds,

[0013] -X is selected from halogen, H, Rf, wherein Rf is selected from:

[0014] -- a C1-C8 fully or partially fluorinated straight or branched chain alkyl group optionally containing a ring, or

[0015] --C1-C3 fully or partially fluorinated alkoxy,

[0016] In formula (I), two X's are the same or different, preferably the same,

[0017] - the amount of the one or more compounds of formula (II) is from 0.002% to 5% by weight of the one or more compounds of formula (I). DETAILED DESCRIPTION

[0018] Therefore, the object of the present invention is to provide a liquid composition comprising one or more compounds according to formula (I):

[0019] CFHX-CF2-ORO-CF2-CFHX(I),

[0020] and one or more compounds according to formula (II):

[0021] CFHX-CF2-OR-OH(II).

[0022] In the composition of the present invention, the total amount of the one or more compounds of formula (II) is 0.002% to 5%, preferably 0.005% to 3%, more preferably 0.01% to 2%, most preferably 0.05% to 1% by weight of the total amount of the one or more compounds of formula (I).

[0023] In formula (I) and (II):

[0024] -R is a C2-C10 divalent straight or branched alkyl group, which may contain a ring, an aromatic ring or an oxygen (O) heteroatom participating in an ether bond. R is preferably a C2-C6 divalent straight alkyl group without an aromatic moiety. More preferably, R is selected from:

[0025] -CH2-CH2-,

[0026] –CH2-CH2-CH2-

[0027] -CH2-CH2-O-CH2-CH2-,

[0028] -CH2-CH2-O-CH2-CH2-O-CH2-CH2-,

[0029] -CH2-CH2-CH2-O-CH2-CH2-CH2-

[0030] -CH2-CH2-CH2-O-CH2-CH2-CH2-O-CH2-CH2-CH2-.

[0031] R in the compounds according to formula (I) and (II) may be the same or different, and are preferably the same.

[0032] -X is selected from halogen, H and R f In case X is halogen, it is preferably Cl or F. R f Selected from C1-C8 fully or partially fluorinated straight or branched chain alkyl, or C1-C3 fully or partially fluorinated alkoxy, which may optionally contain a ring.

[0033] Where X is R f In the case of f is a C1-C3 fully fluorinated alkyl group, even more preferably -CF 3。 In further preferred embodiments, X is selected from F, Cl and CF3, and most preferably is F.

[0034] In the composition of the present invention, it is preferred that the total amount of compounds according to formula (I) and (II) is at least 50%, more preferably at least 70%, even more preferably at least 85%, most preferably at least 90% by weight based on the total weight of the composition.

[0035] In one embodiment, the composition of the present invention consists essentially of compounds according to formula (I) and (II). By "consisting essentially of", it is meant that the total amount of compounds according to formula (I) and (II) accounts for at least 95%, preferably at least 97%, most preferably at least 99% by weight, based on the total weight of the composition.

[0036] The composition according to the invention may be prepared by any method known to the skilled person, for example by mixing one or more compounds according to formula (I) with one or more compounds according to formula (II).

[0037] The preferred method for preparing the composition of the invention is the reaction between a difunctional alcohol and a fluorinated olefin in a selected polar aprotic solvent and in the presence of a basic catalyst. This method provides high yields and can be easily carried out under mild conditions and does not require environmentally harmful ingredients, and it allows to directly obtain the composition according to the invention, which already has the desired balance between the compounds according to formula (I) and (II) without the need to mix the different components.

[0038] As will be apparent to the skilled person, one or more compounds according to formula (I) and (II) are hydrofluoroethers. Hydrofluoroethers are defined as chemical compounds having the general formula RO-R', wherein at least one of R and R' comprises at least one CF bond and at least one CH bond.

[0039] One way to form a hydrofluoroether is to react a chemical compound with at least one -OH group, which is part of an alcohol or phenol group, with a fluorinated olefin, which may be partially or fully fluorinated. The reaction between the -OH group and the C=C double bond of the olefin can be described as an addition to the C=C double bond, wherein one of its carbon atoms forms a C-O bond and the other carbon atom forms a C-H bond.

[0040] In the first step (A) of the process of the present invention, a mixture is provided, which mixture comprises one or more polar aprotic organic solvents and one or more difunctional alcohols.

[0041] Suitable polar aprotic organic solvents for use in the process of the present invention are polar aprotic organic solvents having a boiling point of 60 to 170°C, preferably 70 to 90°C, measured at atmospheric pressure (1 atm).

[0042] Particularly suitable polar aprotic solvents for use herein are those bearing a nitrile group, a particularly preferred solvent being acetonitrile.

[0043] Another essential component of the mixture provided in step A of the process of the present invention is a difunctional alcohol. A difunctional alcohol is a chemical compound with two -OH groups, each of which is part of an alcohol group (i.e., it is covalently bonded to an aliphatic carbon atom that is not part of a carbonyl group -C=O).

[0044] These chemical compounds typically correspond to the general formula

[0045] HO-R-OH(III)

[0046] wherein R is as defined above for formula (I) and (II).

[0047] Examples of difunctional alcohols suitable for use in the present invention are ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propanediol, cyclohexanediol, cyclohexanedimethanol.

[0048] When hydrofluoroethers are formed from difunctional alcohols, yields tend to be low because different -OH groups may have different reactivities, especially after one or more of them have reacted with the fluorinated olefin to form the first ether linkage. The process of the present invention allows excellent yields to be obtained using difunctional alcohols.

[0049] In the process of the present invention, one or more difunctional alcohols as defined above are provided in a mixture with one or more polar aprotic solvents selected as defined above. Such solvents are generally good solvents for the difunctional alcohols, so that preferably the provided mixture is homogeneous. The relative amounts of the selected one or more polar aprotic organic solvents and the one or more difunctional alcohols are preferably at least 1:1, preferably at least 2:1, more preferably at least 3:1, most preferably at least 4:1 by weight. Other solvents may be present in the mixture, but preferably the total amount of the one or more difunctional alcohols and the one or more selected polar aprotic solvents is at least 70%, more preferably at least 80%, even more preferably at least 90%, most preferably at least 95% by weight of the mixture.

[0050] In step B of the process of the present invention, the mixture provided in step A is reacted with one or more fluorinated olefins in the presence of a basic catalyst.

[0051] Preferably, the fluorinated olefin is selected from fully halogenated olefins, and more preferably selected from the group consisting of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether, tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), and more preferably TFE.

[0052] The fluorinated olefin may be initially charged to the reaction vessel or may advantageously be fed continuously during the reaction in the desired amount.

[0053] The one or more fluorinated olefins have the general formula

[0054] CFX=CF2(IV),

[0055] in

[0056] -X is selected from halogen, H, Rf, wherein Rf is selected from:

[0057] -- a C1-C8 fully or partially fluorinated straight or branched chain alkyl group optionally containing a ring, or

[0058] --C1-C3 fully or partially fluorinated alkoxy,

[0059] The reaction of compounds with -OH groups with fluorinated olefins can be schematically shown as follows:

[0060]

[0061] According to the definition provided above, the group R1 may also contain other -OH groups (for example, in the case of polyfunctional alcohols). In that case too, the resulting hydrofluoroether will also contain the same -OH groups, so that it can further react with other molecules of fluorinated olefins until all -OH groups have reacted completely, so that their oxygen atoms are all involved in ether-type bonds.

[0062] The reaction can typically be carried out in a preferably sealed stirred reactor. The molar ratio between the -OH groups and the fluorinated olefin is in principle stoichiometric, i.e., in order for the reaction to be complete and without residual reagents, there should be the same molar amount of double bonds from the olefin as the molar amount of -OH groups in the difunctional alcohol. Of course, in the case of the current use of difunctional alcohols, each -OH group can react with a different olefin molecule, so that for one mole of difunctional alcohol, two moles of fluorinated olefins will be required to reach the stoichiometric ratio. Although the stoichiometric ratio between double bonds and OH groups is ideal, the present invention can also be effectively carried out when one component is in molar excess of up to 50%, preferably up to 30%, more preferably up to 20%, most preferably up to 10%. In the case of an excess of one component, the excess component is preferably a fluorinated olefin.

[0063] The alkaline catalyst can be any chemical compound that can produce an alkaline environment (i.e., subtract protons from the reagents, thereby promoting ionic reactions). Preferred alkaline catalysts are selected from inorganic hydroxides (such as NaOH, KOH, LiOH, Ca(OH)2, Mg(OH)2), inorganic salts of weak acids (such as alkali metal phosphates or carbonates), and organic alkaline compounds (such as alcoholates). The most preferred alkaline catalysts are NaOH and KOH.

[0064] The amount of catalyst used is typically 5 to 100%, preferably 10-70%, more preferably 15-50% by mole relative to the total moles of -OH groups.

[0065] Typically, the basic catalyst is added to the reactor under agitation, adding it to the mixture provided in step A. The reactor is then typically sealed and the fluorinated olefin is pumped in gaseous form to a pressure of between 1 and 50 bar, preferably 2-30 bar, more preferably 3-20 bar, most preferably between 4 and 14 bar. In the case where the fluorinated olefin is in liquid form, the olefin can be introduced as a liquid, and if it remains in a liquid state at the reaction temperature, the reaction can be carried out at lower pressures or even at atmospheric pressure.

[0066] The reaction typically starts immediately. Preferably, during the reaction, the reactor is maintained at a temperature of 20° C. to 90° C., preferably 30° C. to 80° C., most preferably 40° C. to 70° C. The reaction time can vary depending on the temperature, pressure and reagents used. Typically, the reaction will require 1 to 20 hours to complete.

[0067] After the reaction is complete, the reactor is typically vented to remove excess fluorinated olefin. At this stage, the reactor contains a liquid reaction mixture comprising one or more compounds of formula (I) and one or more compounds of formula (II), as well as the polar aprotic solvent and the residues of the basic catalyst.

[0068] The one or more compounds of formula (I) and the one or more compounds of formula (II) can be directly extracted from the reaction mixture using known techniques such as distillation (in optional step C of the present invention). However, the reaction mixture obtained in step B still contains dissolved or dispersed solids, typically inorganic solids derived from the basic catalyst, so that direct distillation of the reaction mixture will lead to the accumulation of unwanted solid deposits on the distillation equipment, which, although acceptable on a laboratory scale, is more problematic on an industrial scale because it may force the equipment to be frequently stopped for cleaning / recovery. Therefore, preferably, the reaction mixture is purified to remove catalyst residues and solid by-products before extracting the hydrofluoroether by distillation.

[0069] In one embodiment, the reaction mixture is purified by extraction with water. In another embodiment, the reaction mixture is purified by evaporation and recondensation. These two embodiments will be described in detail below.

[0070] Evaporation / recondensation method:

[0071] In optional step D of the present invention, the liquid reaction mixture directly obtained from the reaction of step B is completely evaporated and recondensed in liquid form to obtain the purified reaction mixture. Any available technology can be used to evaporate the liquid reaction mixture, such as heating and vacuum can be used alone or in combination to evaporate the mixture. Conventional evaporation equipment (such as rotary evaporation equipment) can be used. After the liquid reaction mixture evaporates, a solid residue is formed, which comprises a residual alkaline catalyst and a salt obtained as a by-product of the reaction, and the solid residue can be discarded or recycled.

[0072] The purified reaction mixture obtained in step D (unlike the reaction mixture obtained in step B) is sufficiently pure to be distilled in conventional distillation apparatus. This is carried out in step E of the process of the invention.

[0073] Water extraction method:

[0074] In an optional step F of the process of the present invention, the liquid reaction mixture obtained directly from the reaction of step B is mixed with water and subjected to agitation and or stirring in order to extract water-soluble impurities (such as residues of the basic catalyst and other impurities and by-products) in the aqueous phase. The relative amounts of water and reaction mixture used in this step are 1:15 to 15:1, preferably 1:5 to 5:1, more preferably 2:1 to 1:2 by weight. Agitation can be carried out by any suitable technique for extraction as known to the skilled person, and a separatory funnel or similar equipment can be used to separate the aqueous phase from the phase containing the aprotic polar solvent and the hydrofluoroether. The resulting phase containing the aprotic polar solvent and the hydrofluoroether, once separated from the aqueous phase, constitutes a purified reaction mixture that is sufficiently pure to be subjected to distillation in conventional distillation equipment in step G of the process of the present invention.

[0075] In all embodiments, distillation allows the hydrofluoroether to be separated from the solvent. The distillation can be carried out using conventional techniques and can be repeated if necessary to further purify the composition. Typically, the solvent will be recovered for reuse using known methods.

[0076] The evaporation / recondensation method described above is generally preferred over the water extraction method because the water extraction method produces a large amount of waste water which is contaminated with impurities of the system and therefore needs to be treated before disposal or reuse.

[0077] Both processes result in a composition according to the invention, wherein the composition consists essentially of one or more hydrofluoroethers according to formula (I) and one or more hydrofluoroethers of formula (II) in the weight ratios required by the invention.

[0078] The method of the present invention can be carried out under mild conditions and, in addition, a very high yield of hydrofluoroether is obtained.

[0079] Should the disclosure of any patents, patent applications, and publications incorporated herein by reference conflict with the description of the present application to the extent that it might render a term unclear, the present description shall take precedence.

[0080] The present invention will now be described in more detail with reference to the following examples, the purpose of which is illustrative only and is not intended to limit the scope of the present invention. If the disclosure of any patent, patent application and publication incorporated herein by reference conflicts with the description of the present application to the extent that a term may be unclear, then this description should take precedence.

[0081] Examples

[0082] analyze:

[0083] The products were identified by NMR (F-NMR and H-NMR) and GC and GC-MS analysis (GC using CP-WAX52CB column and CP-Sil8CB column for GC-MS peak assignment).

[0084] Example 1 - Ethylene glycol + TFE + evaporation

[0085] 37 g of ethylene glycol, 211 g of acetonitrile and 9.4 g of sodium hydroxide were loaded into a 600 ml stirred Hastelloy reactor. After purging with nitrogen and a vacuum of 0.3 bar, the reactor was heated at 50° C. and pressurized to 11 bar with TFE (tetrafluoroethylene) under stirring.

[0086] After 6 hours the stirring was stopped, the reactor was cooled and after purging the TFE residue with nitrogen, the reaction mixture was recovered, rinsed with 106 g of additional acetonitrile and discharged.

[0087] The collected reaction mixture (480 g) was then transferred to a glass flask and evaporated in a rotary evaporator under a vacuum of 1 mbar, the flask being heated to 90° C. The solid by-product (14.5 g) was discarded and the clear, colorless purified reaction mixture (445 g) was collected.

[0088] The purified reaction mixture is then distilled in a glass distillation apparatus (equipped with a vacuum pump) with a flask, a packed column and a condenser. The distillation is carried out with the temperature rising from 100° C. to 155° C. and the pressure falling from 950 mbar to 50 mbar. The distillate contains 142 g of diether HCF2CF2-O-CH2CH2-O-CF2CF2H and 0.02 g of monoether HCF2CF2-O-CH2CH2-OH (0.01% by weight of the diether). The yield of the entire process is 90.3% based on the loading of ethylene glycol.

[0089] Example 2 - Ethylene glycol + TFE + water extraction

[0090] 7231g acetonitrile, 2200g ethylene glycol and 1290g sodium hydroxide are loaded into the Hastelloy reactor of 22L stirring.After purging 4 times with nitrogen and at a vacuum of 0.3 bar, the reactor is heated at 60 ℃, and under stirring, pressurized to 3.5 bar with TFE (tetrafluoroethylene), and continuously fed with TFE to maintain initial pressure.In this reaction process, the reactor is cooled because the reaction is violent and exothermic.Consume about 1300g / h of TFE.After 7.5 hours, the reaction stops, and the TFE supply is stopped.The reactor is placed at 60 ℃ and stirred and cooled to 25 ℃, purged with nitrogen for excessive TFE, the reaction mixture is recovered and discharged.

[0091] The collected reaction mixture was then transferred to a 200 L container and washed with 150 L of demineralized water, stirred at 25 ° C for 6 hours and left to separate for 10 hours. The bottom organic layer (9300 g) was then separated and placed in a distillation column (length 2.70 m, inner diameter 40 mm, filled with filler 1 / 4” cylinder, and 10 L bottom reboiler).

[0092] The distillation of the hydrofluoroether was carried out at 81° C. under reduced pressure (about 80 mbar) (reflux ratio 10:1).

[0093] The hydrofluoroether mixture obtained was 8060 g and was found to contain 8052 g of the diether HCF2CF2-O-CH2CH2-O-CF2CF2H and 8 g of the monoether HCF2CF2-O-CH2CH2-OH (0.1% by weight of the diether). The yield of the entire process was 86% based on the loading of ethylene glycol.

[0094] When comparing the purity and yield of the process of the present invention with those of the prior art, it is clear that the process of the present invention provides a higher yield, a higher purity of the hydrofluoroether obtained.

[0095] A person skilled in the art may make possible modifications and / or additions to the embodiments disclosed and illustrated above while remaining within the scope of the following claims.

Claims

1. A liquid composition comprising one or more compounds of formula (I): CFHX-CF2-ORO-CF2-CFHX(I), One or more compounds of formula (II): CFHX-CF2-OR-OH(II) in: - R in formula (I) and (II) is independently selected from C2-C10 divalent linear or branched alkyl groups, which may optionally contain rings, aromatic rings and / or oxygen heteroatoms participating in ether bonds, -X is selected from halogen, H, Rf, wherein Rf is selected from: -- a C1-C8 fully or partially fluorinated straight or branched chain alkyl group optionally containing a ring, or --C1-C3 fully or partially fluorinated alkoxy, In formula (I), two X's are the same or different, preferably the same, - the amount of the one or more compounds of formula (II) is from 0.002% to 5% by weight of the one or more compounds of formula (I).

2. The composition according to claim 1, wherein R is selected from: -CH2-CH2-, –CH2-CH2-CH2- -CH2-CH2-O-CH2-CH2-, -CH2-CH2-O-CH2-CH2-O-CH2-CH2-, -CH2-CH2-CH2-O-CH2-CH2-CH2- -CH2-CH2-CH2-O-CH2-CH2-CH2-O-CH2-CH2-CH2-.

3. The composition according to claim 1 or 2, wherein X is selected from halogen, H and R f , R f Selected from C1-C8 fully or partially fluorinated straight or branched chain alkyl, or C1-C3 fully or partially fluorinated alkoxy, which may optionally contain a ring.

4. A composition according to any preceding claim, wherein R is -CH2-CH2-, and X is F.

5. A composition according to any preceding claim, wherein The amount of the one or more compounds of formula (II) is 0.005% to 3%, preferably 0.01% to 2%, more preferably 0.05% to 1% by weight of the total amount of the one or more compounds of formula (I).

6. A composition according to any preceding claim, wherein The total amount of compounds according to formula (I) and (II) is at least 50%, more preferably at least 70%, even more preferably at least 85%, most preferably at least 90% by weight based on the total weight of the composition.

7. A method for preparing a composition as claimed in claims 1 to 6, the method comprising: A) providing a mixture comprising one or more polar aprotic organic solvents and one or more difunctional alcohols, the one or more polar aprotic organic solvents having a boiling point of 60° C. to 170° C., preferably 70° C. to 90° C., measured at atmospheric pressure, the one or more difunctional alcohols having the general formula: HO-R-OH(III) wherein R- is selected from C2-C10 divalent straight or branched alkyl groups, which may optionally contain rings, aromatic rings and / or O heteroatoms participating in ether bonds, B): reacting the one or more divalent alcohols with one or more fluorinated olefins having the general formula: CFX=CF2(IV) in -X is selected from halogen, H, Rf, wherein Rf is selected from: -- a C1-C8 fully or partially fluorinated straight or branched chain alkyl group optionally containing a ring, or --C1-C3 fully or partially fluorinated alkoxy, Thereby providing a reaction mixture comprising one or more hydrofluoroethers.

8. The method according to claim 7, wherein: The fluorinated olefin is TFE.

9. The method according to claim 7 or 8, wherein: The one or more compounds of formula (III) are selected from divalent alcohols, and are preferably ethylene glycol.

10. The process according to claims 7-9, wherein the one or more polar aprotic organic solvents is acetonitrile.

11. The process according to claims 7-10, comprising an additional step C, wherein the hydrofluoroether is extracted directly from the reaction mixture, preferably by distillation.

12. The method according to claims 7-10, wherein: The method further comprises the following steps D) completely evaporating the reaction mixture and recondensing it in liquid form into a purified reaction mixture; E) isolating said hydrofluoroether in purified form from said purified reaction mixture by distillation.

13. The method according to claims 7-10, wherein: The method further comprises the following steps F) mixing the reaction mixture with water, agitating the mixture, thereby extracting water-soluble impurities from the reaction mixture, and separating the purified reaction mixture into a water-immiscible phase; G) isolating the hydrofluoroether in purified form from said purified reaction mixture by distillation.

Images