A method for preparing perfluoropolyether compound

Abstract

The invention discloses a method for preparing a perfluoropolyether compound, and belongs to the technical field of polymer fluorine materials. The method for preparing the perfluoropolyether compound comprises: (1) in an inert gas atmosphere, a polymer containing ethylene glycol units and / or propylene glycol units, a fluorine-containing solvent, a fluoride supplement and fluorine gas are subjected to a first fluorination reaction to obtain an intermediate I; (2) the intermediate I is subjected to a second fluorination reaction with an unsaturated fluorine-containing hydrocarbon to obtain an intermediate II; (3) the intermediate II is subjected to an esterification reaction with an organic alcohol solution I to obtain an intermediate III; (4) the intermediate III is subjected to a reduction reaction with a reducing agent to obtain a perfluoropolyether compound; the preparation method provided by the invention has excellent effects such as cheap and readily available raw materials, high fluorination efficiency, less by-products, and a more stable structure of the perfluoropolyether compound.

Description

Technical Field

[0001] The invention relates to the technical field of polymer fluorine materials, and in particular to a method for preparing a perfluoropolyether compound. Background Art

[0002] Perfluoropolyether (PFPE) is a special type of perfluorinated polymer compound with an average molecular weight of 500 to 15,000. There are only three elements, C, F, and O, in its molecules. It is a colorless, odorless, transparent liquid at room temperature. Because of the saturated end groups and a large number of fluorinated groups, it has the characteristics of heat resistance, oxidation resistance, radiation resistance, corrosion resistance, low volatility, and non-combustibility. It also has good comprehensive properties such as compatibility with plastics, elastomers, and metal materials.

[0003] Perfluoropolyether was initially used mainly in cutting-edge fields such as military, aerospace, and nuclear industry. Today, it is widely used in chemical, electronic, electrical, mechanical, magnetic media, nuclear industry, aerospace, and other fields as lubricants, vacuum pump oils, greases, and thermal fluids.

[0004] Perfluoropolyether can be made from hexafluoropropylene or tetrafluoroethylene, and through photooxidation reaction, an intermediate product of polyfluoroether oil is generated under the action of a telogen, and then the carbonyl or carboxyl end groups are treated by different methods to obtain fluoroalkyl polyfluoroether oil with saturated end groups. As a fluorine chemical product, there are problems such as the difficulty in obtaining raw materials and harsh reaction conditions in its preparation process. In addition, the traditional fluorine gas end-capping process has the following two disadvantages. First, the reaction temperature of the traditional direct fluorination end-capping process is above 180°C. Side reactions often occur during high-temperature reactions, causing the perfluoropolyether base oil to turn black. In extreme cases, the reaction is too violent, and even explosions may occur in the reactor; second, the reaction efficiency is particularly low, the duration is long, and the fluorine gas utilization rate is low. Usually, the amount of fluorine gas used is more than 5 times the theoretical amount, and high-concentration fluorine gas fluorination has greater safety risks and high costs.

[0005] The Chinese patent (publication number CN106893090A) uses unsaturated fluoroether polymers obtained by photocatalysis of hexafluoropropylene and / or tetrafluoroethylene as raw materials, and uses relatively high concentrations of fluorine gas to directly fluorinate the carboxyl and carbonyl groups in perfluorinated organic matter. Although it avoids the low reaction efficiency caused by too low fluorine gas concentration, the use of high concentrations of fluorine gas poses a high risk of explosion.

[0006] In view of the problems of raw materials being difficult to obtain and harsh reaction conditions in perfluoropolyether, the Chinese patent (publication number CN115558114A) provides a new method for preparing perfluoropolyether oil, wherein a perfluoropolyether raw material containing acyl fluoride groups and / or carboxylic acid groups is subjected to esterification or amidation reaction with a precursor compound containing alcohol hydroxyl groups or amino groups to obtain a block copolymer precursor of perfluoropolyether, and then the block copolymer precursor of perfluoropolyether is subjected to fluorination reaction to finally obtain perfluoropolyether oil. This patent solves the problems of small production capacity and low production efficiency caused by the difficulty in preparation and synthesis and process limitations when only perfluoropolyether carboxylic acid is used as raw material in the prior art. However, fluorine gas concentration and fluorination temperature are still two important factors affecting production efficiency.

[0007] The existing methods for fluorination of hydrocarbons mainly include fluorine gas fluorination and electrochemical fluorination. Among them, electrochemical fluorination is prone to isomerization reactions, CC disconnection and recombination reactions, etc., and there is a problem that the target compound cannot be obtained well. However, in gas phase reactions, there are also some inevitable problems, such as it is difficult to control the concentration of fluorine gas to improve production efficiency and reduce safety risks. Based on the special activity of fluorine gas, direct fluorination reaction requires controlling high reaction heat to obtain perfluorinated or selective fluorinated products. The general method is to select a suitable solvent to react in the liquid phase, in which the fluorine gas is diluted with an inert gas. However, when using a solvent for fluorine gas fluorination, the degree of fluorination of the perfluoropolyether product is low due to the fluorination of the solvent. Summary of the invention

[0008] In view of the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing perfluoropolyether compounds, which can avoid the risk of explosion and chain scission reaction caused by the presence of high concentration of fluorine gas, and can also overcome the problem of low fluorination degree of perfluoropolyether compounds caused by fluorination of solvents in the prior art. Compared with the traditional fluorination process of fluorine gas, the preparation method provided by the present invention has the advantages of high fluorination degree, high conversion efficiency and high safety.

[0009] In order to achieve the above object, the present invention provides a method for preparing a perfluoropolyether compound, the method comprising:

[0010] (1) Under an inert gas atmosphere, a polymer containing ethylene glycol units and / or propylene glycol units, a fluorinated solvent, a fluoride supplement and fluorine gas are subjected to a first fluorination reaction to obtain an intermediate I;

[0011] (2) subjecting the intermediate I to a second fluorination reaction with an unsaturated fluorine-containing hydrocarbon to obtain an intermediate II;

[0012] (3) subjecting the intermediate II to an esterification reaction with an organic alcohol solution I to obtain an intermediate III;

[0013] (4) subjecting the intermediate III to a reduction reaction with a reducing agent to obtain a perfluoropolyether compound;

[0014] The structural formula of the polymer containing ethylene glycol units and / or propylene glycol units is as follows:

[0015] R2-R1-O-[(CH2CH2O) n -(CH2CH2CH2O) m -(CH2CH2O) x -(CH2CH2CH2O) y ]-R1-R2;

[0016] Each R1 is the same or different, and each R1 is independently selected from one of -CO-, -SO2-, -O-, C1~C3 alkylene, -CONR-, and -SO2NR-; wherein R is selected from one of C1~C3 alkylene; each R2 is the same or different, and each R2 is independently selected from one of C1~C6 alkyl, C1~C6 alkyl substituted by halogen, vinyl, allyl, phenyl, and amino;

[0017] Definition: In a polymer containing ethylene glycol units and / or propylene glycol units, n, m, x and y are the numbers of their corresponding structural units, and 500≤n+m+x+y≤5000.

[0018] In step (1), the fluorinated solvent is a combination of a perfluorinated solvent and a non-perfluorinated solvent in a molar ratio of 1:1 to 2; the perfluorinated solvent is at least one selected from perfluorotributylamine, perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, and perfluoroheptane; the non-perfluorinated solvent is at least one selected from ethyl perfluorobutyl ether, ethyl perfluoroethyl ether, isobutyl perfluoroethyl ether, methyl perfluorobutyl ether, and trifluorotoluene;

[0019] The key technical point of the present invention is to fluorinate the raw material with fluorine gas in the fluorine-containing solvent provided by the present invention (a combination of a perfluorinated solvent and a non-perfluorinated solvent in a molar ratio of 1:1 to 2). This is mainly because the non-perfluorinated solvent has a good dissolving effect on fluorine gas, but is easily fluorinated and loses its effect during the fluorination process, while the perfluorinated solvent has a dissolving effect that is not as good as that of the non-perfluorinated solvent, but is not easily fluorinated. The selection of these two combinations can complement each other, improve the fluorination efficiency, and the yield of the perfluoropolyether compound product, and can also effectively avoid the chain breaking reaction caused by too high a fluorine concentration and the poor fluorination effect caused by too low a fluorine concentration.

[0020] Furthermore, the preparation method provided by the present invention is different from the traditional fluorine gas capping process. The present invention obtains a perfluoropolyether compound with a hydroxyl terminal group through esterification and esterification reduction reaction, which has the characteristics of high conversion efficiency and high safety.

[0021] At the same time, the present invention uses cheap and readily available polymers containing ethylene glycol units and / or propylene glycol units as raw materials, and prepares perfluoropolyether compounds by fluorination with fluorine gas under the action of the fluorine-containing solvent provided by the present invention, which has the characteristics of cheap and readily available raw materials, high product yield, and few by-products.

[0022] Preferably, in step (1), the fluoride supplement is selected from at least one of NaF, KF, and AgF; the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the fluoride supplement is 1:0.6-4. The fluoride supplement can inhibit the decomposition reaction of hydrogen fluoride on the ether bond and carry out a high-yield fluorination reaction.

[0023] Preferably, in step (1), the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the fluorine-containing solvent is 1:1.5-5.

[0024] Preferably, in step (1), the flow rate ratio of the fluorine gas to the inert gas is 0.1-0.5:1; the flow rate of the fluorine gas is 40-120 mL / min. The preparation of perfluoropolyether compounds at low concentration can obtain perfluoropolyether compounds with high yield, high selectivity and less by-products.

[0025] Preferably, in step (1), the conditions of the first fluorination reaction include: temperature of 10-30° C. and time of 1-24 h.

[0026] Preferably, in step (1), the conditions of the first fluorination reaction also include: a pressure of 0.1-0.15 MPa.

[0027] According to a preferred embodiment, the method further comprises, in step (1), first adding a fluorine-containing solvent and a fluoride supplement into a reactor, stirring them sufficiently and then purging them with an inert gas, continuing to introduce the inert gas and fluorine gas into the reactor together, and finally adding a polymer containing ethylene glycol units and / or propylene glycol units to carry out a first fluorination reaction to obtain an intermediate I.

[0028] Preferably, in step (2), the unsaturation degree of the unsaturated fluorine-containing hydrocarbon is 1-8; the number of fluorine atoms is 2-10, and the number of carbon atoms is 2-10.

[0029] More preferably, the unsaturated fluorine-containing hydrocarbon is selected from at least one of hexafluorobenzene, octafluoronaphthalene, chloropentafluorobenzene, 1,3,5-trichlorotrifluorobenzene, hexafluorobutadiene, octafluorocyclopentene, chlorotrifluoroethylene, chlorotrifluoropropylene and 1,1-dichloro-2,3,3,3-tetrafluoropropylene. A large number of experimental studies have shown that in this preferred case, the unsaturated fluorine-containing hydrocarbon can be miscible with the perfluoropolyether compound, which is more conducive to fluorination, thereby increasing the degree of fluorination.

[0030] Preferably, the flow rate ratio of the fluorine gas to the unsaturated fluorine-containing hydrocarbon is 2.5-15:1.

[0031] Preferably, in step (2), the conditions of the second fluorination reaction include: temperature of 20-40° C. and time of 1-24 h.

[0032] Preferably, in step (2), the conditions of the second fluorination reaction also include: a pressure of 0.1-0.2 MPa.

[0033] Preferably, the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the organic alcohol solution I is 1:3-5.

[0034] According to a preferred embodiment, the method further comprises, in step (2), first removing the fluoride supplement in the intermediate I, and then subjecting the intermediate I from which the fluoride supplement has been removed to a second fluorination reaction with an unsaturated fluorine-containing hydrocarbon to obtain an intermediate II.

[0035] The present invention has no special requirements on the specific method of removing the fluoride supplement, and it can be carried out by methods known in the art. For example, the fluoride supplement can be separated by fiber filter paper.

[0036] Preferably, in step (3), the conditions of the esterification reaction include: pressure of 0.1-0.2 MPa, temperature of 10-30° C., and time of 1-24 h.

[0037] Preferably, in step (4), the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the reducing agent is 1:2-4.

[0038] According to a preferred embodiment, in step (4), the method further comprises: the reduction reaction is carried out in an organic alcohol solution II.

[0039] Preferably, the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the organic alcohol solution II is 1:2-4.

[0040] Preferably, in step (4), the reduction reaction conditions include: temperature of 10-40° C. and time of 1-12 h.

[0041] Preferably, in step (4), the method further comprises washing the product obtained by the reduction reaction with deionized water, and separating and purifying the perfluoropolyether compound by post-treatment methods such as solvent extraction and distillation.

[0042] Preferably, in step (3) and step (4), the organic alcohol solution I and the organic alcohol solution II are each independently selected from an alcohol solution having 1 to 3 carbon atoms.

[0043] More preferably, the organic alcohol solution I and the organic alcohol solution II are each independently selected from at least one of methanol, ethanol and n-propanol.

[0044] It should be noted that the present invention has no special requirements for the reducing agent, and any reducing agent known in the art can be used. According to a preferred embodiment, the reducing agent is selected from at least one of sodium borohydride, lithium borohydride, and lithium aluminum hydride.

[0045] The perfluoropolyether compound prepared by the present invention can be used as lubricating oil.

[0046] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0047] (1) The present invention uses a polymer containing ethylene glycol units and / or propylene glycol units as a raw material to prepare a perfluoropolyether compound, which has a lower cost than using hexafluoropropylene or tetrafluoroethylene as a raw material to prepare a perfluoropolyether compound. Furthermore, the perfluoropolyether compound formed by using a polymer containing ethylene glycol units and / or propylene glycol units is more stable in structure.

[0048] (2) The present invention uses a combination of a perfluorinated solvent and a non-perfluorinated solvent in a molar ratio of 1:1 to 2 as a solvent and is combined with the other technical features of the present invention. It can effectively improve the fluorination efficiency and the yield of the perfluoropolyether compound product while performing the fluorination reaction under low concentration of fluorine gas. Furthermore, it can effectively avoid the chain breaking reaction caused by too high fluorine gas concentration and the poor fluorination effect caused by too low fluorine gas concentration. In addition, when the fluoride supplement coexists in the reaction system, the decomposition reaction of hydrogen fluoride on the ether bond can be suppressed, so that a high-yield fluorination reaction can be performed.

[0049] (3) The present invention uses unsaturated fluorine-containing hydrocarbons for the second fluorination, thereby increasing the degree of fluorination.

[0050] (4) The present invention adopts a relatively mild treatment method to replace the traditional fluorine gas end-capping process to end-cap the perfluoropolyether compound. First, an alcohol solution is used to carry out an esterification reaction, and then the ester group is reduced with an alcohol solution and a reducing agent to obtain a hydroxyl group. Compared with the traditional fluorine gas fluorination process, this method has the characteristics of high conversion efficiency and high safety.

[0051] (5) The preparation method provided by the present invention has the characteristics of high product selectivity, few by-products, and relatively simple synthesis process, and is expected to expand production capacity and be applied to industrial-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The main product of Example 1 is OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -H NMR spectrum of CH2-OH;

[0053] Figure 2 The by-product 1 of Example 1 is OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -H NMR spectrum of CH3;

[0054] Figure 3 Byproduct 2 of Example 1 CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -H NMR spectrum of CH3;

[0055] Figure 4 Byproduct 3 of Example 1 CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -H NMR spectrum of CH2-OH. DETAILED DESCRIPTION

[0056] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0057] In the present invention, “C 1~6The term "alkyl" refers to a straight-chain alkyl group having 1 to 6 carbon atoms or a branched-chain alkyl group or a cycloalkyl group having 3 to 6 carbon atoms, for example, a straight-chain alkyl group having 1, 2, 3, 4, 5 or 6 carbon atoms, a branched-chain alkyl group or a cycloalkyl group having 3, 4, 5 or 6 carbon atoms, including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, etc.

[0058] "C1-C6 alkyl substituted by halogen" means a straight chain alkyl or a branched chain alkyl or a cycloalkyl group having a total of 1 to 6 carbon atoms, and at least one H atom on the alkyl group is substituted by halogen; for example, a straight chain alkyl group having a total of 1, 2, 3, 4, 5 or 6 carbon atoms, and at least one H atom on the alkyl group is substituted by halogen, a branched chain alkyl or a cycloalkyl group having a total of 3, 4, 5 or 6 carbon atoms, and at least one H atom on the alkyl group is substituted by halogen, including but not limited to a methyl group substituted by 1 halogen, an ethyl group substituted by 1 halogen, an n-propyl group substituted by 1 halogen, an isopropyl group substituted by 1 halogen, etc. "Halogen" includes fluorine, chlorine, bromine, and iodine.

[0059] In the present invention, “C 1~6 The term "alkylene" refers to a straight-chain or branched-chain alkylene having 1 to 6 carbon atoms. The alkylene refers to the residue of an alkane after losing two hydrogen atoms, wherein the two hydrogen atoms may be two hydrogen atoms on the same carbon atom or two hydrogen atoms on different carbon atoms, and may be a straight-chain or branched-chain alkylene having, for example, a straight-chain alkylene having a total number of carbon atoms of 1, 2, 3, 4, 5 or 6, or a branched-chain alkylene having a total number of carbon atoms of 3, 4, 5 or 6. 1~6 The alkylene group may include, but is not limited to, -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CH(CH3)-CH2-, -CH2-CH(CH3)-, -CH2-(CH2)2-CH2-, -C(CH3)2-CH2-, -CH2-C(CH3)2-, and the like.

[0060] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by professionals in this field without creative work still belong to the protection scope of the present invention.

[0061] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0062] Example 1

[0063] The structural formula of the polymer containing ethylene glycol units and / or propylene glycol units is: CH3COO-[(CH2CH2O) 500 -(CH2CH2CH2O) 500 ]-COCH3;

[0064] (1) A fluorine-containing solvent (0.4 mol, which is a combination of perfluorotributylamine and trifluorotoluene in a molar ratio of 1:1) and NaF (0.09 mol) are added to a high-pressure reactor, stirred thoroughly, purged with nitrogen at a rate of 800 mL / min, and then nitrogen and fluorine are introduced into the high-pressure reactor at a rate of 450 mL / min and 50 mL / min, respectively, for circulation. Finally, a polymer of ethylene glycol units and / or propylene glycol units (0.1 mol) is dissolved in a mixed solvent for a first fluorination reaction. The reaction temperature is 20° C., the pressure of the autoclave is 0.1 MPa, and the reaction time is 20 h to obtain an intermediate I.

[0065] (2) Open the autoclave in a nitrogen atmosphere glove box, then pass the intermediate I through a cellulose filter paper to separate NaF, and continue to introduce hexafluorobenzene at a flow rate of 5 mL / min to carry out a second fluorination reaction to obtain intermediate II; the pressure is 0.1 MPa, the reaction temperature is 30°C, and the reaction time is 8 h to obtain intermediate II;

[0066] (3) Esterification reaction of intermediate II with methanol (0.4 mol) to obtain intermediate III; the conditions of the esterification reaction are: pressure 0.1 MPa, time 12 h, temperature 20 °C;

[0067] (4) The intermediate III was subjected to reduction reaction with NaBH4 (0.25 mol) and ethanol (0.25 mol). After the reaction was completed, it was washed with deionized water and extracted with tetrachlorohexafluorobutane. The recovered liquid was separated by distillation. The conditions of the reduction reaction were: temperature of 20°C and time of 8 h.

[0068] After HNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0069] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH accounts for 80wt%,

[0070] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500-CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH these three substances account for 5wt% in total,

[0071] The remaining 15 wt% are incompletely fluorinated compounds.

[0072] The present invention exemplarily provides a hydrogen nuclear magnetic resonance spectrum of some products prepared in this embodiment, OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH H NMR spectrum is shown in Figure 1 , OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3 hydrogen nuclear magnetic resonance spectrum is shown in Figure 2 , CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3 H NMR spectrum see Figure 3 , CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH H NMR spectrum is shown in Figure 4 .

[0073] Example 2

[0074] The structural formula of the polymer containing ethylene glycol units and / or propylene glycol units is: CH3COO-[(CH2CH2O) 1000 -(CH2CH2CH2O) 1000 ]-COCH3;

[0075] (1) A fluorinated solvent (0.2 mol, a combination of perfluorocyclohexane and methyl perfluorobutyl ether in a molar ratio of 1:1.5) and KF (0.35 mol) were added to a high-pressure reactor, fully stirred, purged with 800 mL / min of nitrogen, and then nitrogen and fluorine were introduced into the high-pressure reactor at flow rates of 500 mL / min and 100 mL / min, respectively, for circulation. Finally, a polymer of ethylene glycol units and / or propylene glycol units (0.1 mol) was dissolved in a mixed solvent for a first fluorination reaction. The reaction temperature was 30° C., the pressure of the autoclave was 0.15 MPa, and the reaction time was 10 h to obtain an intermediate I.

[0076] (2) Open the autoclave in a nitrogen atmosphere glove box, then pass the intermediate I through a cellulose filter paper to separate NaF, and continue to pass octafluoronaphthalene at a flow rate of 20 mL / min to carry out a second fluorination reaction to obtain intermediate II; the reaction temperature is 25 ° C, the reaction time is 12 h, and intermediate II is obtained;

[0077] (3) Intermediate II was subjected to esterification reaction with methanol (0.4 mol) to obtain intermediate III; the conditions of the esterification reaction were: pressure 0.15 MPa, time 18 h, temperature 15 °C;

[0078] (4) The intermediate III was subjected to reduction reaction with NaBH4 (0.35 mol) and ethanol (0.35 mol). After the reaction was completed, it was washed with deionized water and extracted with tetrachlorohexafluorobutane. The recovered liquid was separated by distillation. The conditions of the reduction reaction were: temperature of 30°C and time of 6 h.

[0079] After HNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0080] OH-CH2-O-(CF2CF2O) 1000 -(CF2CF2CF2O) 1000 -CH2-OH accounts for 85wt%,

[0081] OH-CH2-O-(CF2CF2O) 1000 -(CF2CF2CF2O) 1000 -CH3, CH3-O-(CF2CF2O) 1000 -(CF2CF2CF2O) 1000 -CH2-OH, CH3-O-(CF2CF2O) 1000 -(CF2CF2CF2O) 1000 -CH3 these three substances account for 5wt% in total,

[0082] The remaining 10 wt% are incompletely fluorinated compounds.

[0083] Example 3

[0084] Example 3 is carried out in a similar manner to Example 1, except that the hexafluorobenzene in step (2) is replaced with an equal flow rate of hexafluoro-2-butyne.

[0085] After HNMR, FNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0086] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500-CH2-OH accounts for 70wt%, OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH these three substances account for 5wt% in total,

[0087] The remaining 25 wt% were incompletely fluorinated compounds.

[0088] Comparative Example 1

[0089] This comparative example was carried out in a similar manner to Example 1, except that in step (1), the fluorine-containing solvent was 0.4 mol trifluorotoluene, did not contain perfluorotributylamine, and no NaF was added in step (1).

[0090] After HNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0091] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH accounts for 50wt%,

[0092] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH these three substances account for 25wt% in total,

[0093] The remaining 25 wt% are incompletely fluorinated compounds.

[0094] Comparative Example 2

[0095] This comparative example is carried out in a similar manner to Example 1, except that in step (1), the fluorine-containing solvent is 0.4 mol trifluorotoluene and does not contain perfluorotributylamine.

[0096] After HNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0097] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH accounts for 65wt%, OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH these three substances account for 5wt% in total,

[0098] The remaining 30 wt% are incompletely fluorinated compounds.

[0099] Comparative Example 3

[0100] Step (1) is the same as in Example 1;

[0101] Step (2) opening the autoclave in a nitrogen atmosphere glove box, and then passing intermediate I through cellulose filter paper to separate NaF to obtain intermediate II;

[0102] Step (3) and step (4) are the same as in Example 1.

[0103] After HNMR and LC-MS analysis, it was found that the composition of the recovered liquid was as follows:

[0104] OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH accounts for 50wt%, OH-CH2-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH3, CH3-O-(CF2CF2O) 500 -(CF2CF2CF2O) 500 -CH2-OH these three substances account for 5wt% in total,

[0105] The remaining 45 wt% were incompletely fluorinated compounds.

[0106] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a perfluoropolyether compound, characterized in that: The method includes: (1) Under an inert gas atmosphere, a polymer containing ethylene glycol units and / or propylene glycol units, a fluorine-containing solvent, a fluoride supplement and fluorine gas are subjected to a first fluorination reaction to obtain an intermediate I; the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the fluorine-containing solvent is 1:1.5-5; the fluoride supplement is selected from at least one of NaF, KF and AgF; (2) subjecting the intermediate I to a second fluorination reaction with an unsaturated fluorine-containing hydrocarbon to obtain an intermediate II; the unsaturated fluorine-containing hydrocarbon is at least one selected from hexafluorobenzene, octafluoronaphthalene, chloropentafluorobenzene, 1,3,5-trichlorobenzene trifluoride, hexafluorobutadiene, octafluorocyclopentene, chlorotrifluoroethylene, chlorotrifluoropropylene and 1,1-dichloro-2,3,3,3-tetrafluoropropylene; (3) subjecting the intermediate II to an esterification reaction with an organic alcohol solution I to obtain an intermediate III; (4) subjecting the intermediate III to a reduction reaction with a reducing agent to obtain a perfluoropolyether compound; In step (1), the fluorinated solvent is a combination of a perfluorinated solvent and a non-perfluorinated solvent in a molar ratio of 1:1 to 2; the perfluorinated solvent is at least one selected from perfluorotributylamine, perfluorohexane, perfluorocyclohexane, perfluoromethylcyclohexane, and perfluoroheptane; the non-perfluorinated solvent is at least one selected from ethyl perfluorobutyl ether, ethyl perfluoroethyl ether, isobutyl perfluoroethyl ether, methyl perfluorobutyl ether, and trifluorotoluene; The structural formula of the polymer containing ethylene glycol units and / or propylene glycol units is as follows: R2-R1-O-[(CH2CH2O) n -(CH2CH2CH2O) m -(CH2CH2O) x -(CH2CH2CH2O) y ]-R1-R2; R1 is -CO-; each R2 is the same or different, and each R2 is independently selected from one of a C1-C6 alkyl group, a C1-C6 alkyl group substituted with a halogen, a vinyl group, an allyl group, a phenyl group, and an amino group; Definition: In a polymer containing ethylene glycol units and / or propylene glycol units, n, m, x and y are the numbers of their corresponding structural units, and 500≤n+m+x+y≤5000.

2. The preparation method according to claim 1, characterized in that: In step (1), the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the fluoride supplement is 1:0.6-4.

3. The preparation method according to claim 1 or 2, characterized in that: In step (1), the flow rate ratio of the fluorine gas to the inert gas is 0.1-0.5:1; the flow rate of the fluorine gas is 40-120 mL / min; And / or, in step (1), the conditions of the first fluorination reaction include: temperature of 10-30° C. and time of 1-24 h.

4. The preparation method according to claim 1 or 2, characterized in that: The flow rate ratio of the fluorine gas to the unsaturated fluorine-containing hydrocarbon is 2.5-15:

1.

5. The preparation method according to claim 1 or 2, characterized in that: In step (2), the conditions of the second fluorination reaction include: temperature of 20-40° C. and time of 1-24 h.

6. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the organic alcohol solution I is 1:3-5; And / or, in step (3), the conditions of the esterification reaction include: pressure of 0.1-0.2 MPa, temperature of 10-30° C., and time of 1-24 h.

7. The preparation method according to claim 1 or 2, characterized in that: In step (4), the molar ratio of the polymer containing ethylene glycol units and / or propylene glycol units to the reducing agent is 1:2-4.

8. The preparation method according to claim 1 or 2, characterized in that: In step (4), the reduction reaction conditions include: temperature of 10-40° C. and time of 1-12 h.

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