Patent Description:
Fluoropolyether group-containing compounds are widely used as e.g. surface-treating agents and lubricants, and their applications have been further expanded.

Ring-opening polymerization of a cyclic ether such as tetrafluorooxetane or hexafluoropropylene oxide, for example, is known as one of the methods for producing a fluoropolyether group-containing compound. However, with such a method, a compound having a functional group only at one end of the molecular chain is usually obtained, and it is difficult to obtain a compound having a functional group at both ends of the molecular chain.

<CIT> relates to a process for preparing halogen-containing polyether, comprising ring-opening polymerizing <NUM>,<NUM>,<NUM>,<NUM>-tetrafluorooxetane in an aprotic solvent in the presence of an alkali metal halide or an alkali metal fluoride and an acyl fluoride, which reacts with the alkali metal fluoride to generate alkoxy anion, or trimethylamine as polymerization initiator, and optionally fluorinating and/or chlorinating the resulting polyether product.

<NPL>) describes describes the conversion of Ω-iodoperfluoro (polyether) esters of the formula IRfORfCO<NUM>R via zinc coupling reactions to yield alpha, omega-perfluoro(polyether) diesters as starting materials for the synthesis of a variety of other difunctional compounds of high molecular weight and exhibiting a variation of oxygen-carbon ratio.

Conventionally, in order to obtain a fluoropolyether group-containing compound having a functional group at both ends of the molecular chain, it has been necessary to use a special initiator (<CIT>). In particular, it has been difficult to obtain a fluoropolyether group-containing compound having different functional groups at both ends by such a production method.

An object of the present disclosure is to provide a novel fluoropolyether group-containing compound and a method for producing the same.

The present invention provides a compound, which is a fluoropolyether-containing compound of formula (1a) or (1b):.

provided that in formula (1a) Ra and Rb are not the same, and in formula (1b) R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM>.

Also, the present invention provides a method for producing a compound of formula (A):.

comprising reacting an acid fluoride compound of the formula (a) :.

with a cyclic ether compound of formula (b):
<CHM>
wherein R<NUM> is linear C<NUM>-<NUM>-fluoroalkylene.

The present invention provides a novel fluoropolyether group-containing compound (also referred to as "the present compound" hereinafter) that can be used in various applications. Further, by using a specific initiator, a fluoropolyether group-containing compound having functional groups at both ends can be easily produced.

Hereinafter, the present compound will be described in detail.

The present invention provides a fluoropolyether group-containing compound of the following formula (1a) or (1b):.

provided that (i) Ra and Rb are not the same, and/or (ii) R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM>.

In one embodiment, in the present compound of formula (1a) Ra and Rb are not the same.

In one embodiment, in the present compound of formula (1b) R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM>.

The formulas (1a) and (1b) are different in that Ra and Rb are different in the formula (1a), whereas Ra and Rb may be the same or different in the formula (1b) and R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM> in formula (1b).

In the formula, Ra is COF, COOR<NUM>, CH<NUM>OH, or CHO, preferably COF or COOR<NUM>, and more preferably COF.

In the formula, Ra is COF, COOR<NUM>, CH<NUM>OH, or CHO, and preferably COOR<NUM>.

In the formula, R<NUM> each independently is H or C<NUM>-<NUM>-alkyl optionally substituted with F, and preferably C<NUM>-<NUM>-alkyl optionally substituted with F. The C<NUM>-<NUM>-alkyl in R<NUM> is preferably C<NUM>-<NUM>-alkyl, more preferably methyl or ethyl, and still more preferably methyl.

In formula (1a), Ra and Rb are groups different from each other.

In formula (1b), Ra and Rb may be the same group or groups different from each other. In one embodiment, Ra and Rb are the same, and in another embodiment they are different.

In one embodiment, the combination of Ra and Rb is COF and COOR<NUM> or COOR<NUM> and COOR<NUM>, and preferably COF and COOR<NUM>.

In the formulae (1a) and (1b), R<NUM> is C<NUM>-<NUM>-alkylene optionally substituted with F. The C<NUM>-<NUM>-alkylene in R<NUM> is preferably C<NUM>-<NUM>-alkylene, more preferably C<NUM>-<NUM>-alkylene, and still more preferably C<NUM>-alkylene.

In one embodiment, the alkylene group in R<NUM> is fluoroalkylene, and preferably perfluoroalkylene.

In a preferred embodiment, R<NUM> is linear C<NUM>-<NUM>-perfluoroalkylene, and more preferably -CF<NUM>CF<NUM>-.

In formula (1a), R<NUM> is -R6a-(OR5a)n-O-.

R5a is linear C<NUM>-<NUM>-fluoroalkylene, preferably C<NUM>-<NUM>-fluoroalkylene, more preferably C<NUM>-<NUM>-fluoroalkylene, and still more preferably C<NUM>-fluoroalkylene.

In a preferred embodiment, R5a is CF<NUM>CF<NUM>CH<NUM> or CF<NUM>CF<NUM>CF<NUM> preferably CF<NUM>CF<NUM>CH<NUM>.

In the formula, R6a is a linear C<NUM>-<NUM>-fluoroalkylene, preferably C<NUM>-<NUM>-fluoroalkylene, more preferably C<NUM>-<NUM>-fluoroalkylene, for example, C<NUM>-<NUM>-fluoroalkylene.

In a preferred embodiment, R6a is CF<NUM>CH<NUM> or CF<NUM>CF<NUM>, preferably CF<NUM>CH<NUM>.

In one embodiment, the number of carbon atoms in R5a is one greater than the number of carbon atoms in R6a. For example, when the number of carbon atoms in R5a is <NUM>, the number of carbon atoms in R6a is <NUM>.

In the formula (1b), R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM>.

In the formulae (1a) and (1b), n is an integer of <NUM>-<NUM>, preferably <NUM>-<NUM>, and more preferably <NUM>-<NUM>.

In a preferred embodiment, in the present compound of formula (1a),.

In a more preferred embodiment, in the present compound of formula (1a),.

In a preferred embodiment, in the present compound of formula (1b),.

The number-average molecular weight of the fluoropolyether group-containing compound is not limited, but may be, for example, ≥ <NUM>, preferably ≥ <NUM>,<NUM>, for example ≥ <NUM>,<NUM>, ≥ <NUM>,<NUM>, or ≥ <NUM>,<NUM>. The number-average molecular weight of the fluoropolyether group-containing compound is not limited, but may be, for example, ≤ <NUM>,<NUM>, ≤ <NUM>,<NUM>, ≤ <NUM>,<NUM>, ≤ <NUM>,<NUM>, or ≤ <NUM>,<NUM>.

The dispersion (weight-average molecular weight / number-average molecular weight) of the fluoropolyether group-containing compound is not limited, but may preferably be ≤ <NUM>, more preferably ≤ <NUM>, still more preferably ≤ <NUM>, and particularly preferably ≤ <NUM>.

The number-average molecular weight and the weight-average molecular weight can be determined by F-NMR, and may also be determined by GPC.

The present disclosure provides a composition containing two or more compounds of the formulae (1a) and/or (1b).

In one embodiment, two or more compounds in the composition have different structures in Ra and/or Rb. For example, Rb may be -COO-alkyl in one compound and Rb may be - COOH in the other compound.

The present compound can be suitably used as e.g. a surface-treating agent and a lubricating oil, and an intermediate thereof.

The present invention provides a method for producing the fluoropolyether group-containing compound (also referred to as "the present method" hereinafter).

That is, the present invention provides a method for producing a compound of formula (A):.

According to the present method, the cyclic ether of the formula (b) is bonded to the COF side of the acid fluoride compound of the formula (a). That is, in the present method, the reaction proceeds at one end side of the acid fluoride compound of the formula (a), and the polymer chain extends at such an end. Therefore, it is possible to obtain a compound having a different functional group, that is, one of COF and COOR<NUM>, at each end of the polymer chain. Further, the present method facilitates the adjustment of the degree of polymerization, molecular weight and degree of dispersion, for example, to obtain a compound with the desired molecular weight or to obtain a compound with a small degree of dispersion, because the reaction is easily controlled.

The formula (A) corresponds to the formula (1a) or (1b) in which Ra is COF and Rb is COOR<NUM> (where R<NUM> is C<NUM>-<NUM>-alkyl), and among the symbols of the formula (A), R<NUM> and R<NUM> have the same meaning as the description of formulae (1a) or (1b).

In formula (A), R<NUM> corresponds to R<NUM> of the formula (1a) and (1b) and is C<NUM>-<NUM>-alkyl optionally substituted with F. The C<NUM>-<NUM>-alkyl in R<NUM> is preferably C<NUM>-<NUM>-alkyl, more preferably methyl or ethyl, and still more preferably methyl. In one embodiment, the alkyl is substituted with fluorine and is preferably perfluoroalkyl. In another embodiment, the alkyl group is not substituted.

In formula (a), R<NUM> is C<NUM>-<NUM>-alkyl optionally substituted with F, and has the same meaning as described above.

In formula (a), R<NUM> is C<NUM>-<NUM>-alkylene optionally substituted with F. R<NUM> of formula (A) corresponds to a group in which a carbon atom derived from COF of the formula (a) is bonded to the left end of R<NUM>.

The C<NUM>-<NUM>-alkylene in R<NUM> is preferably C<NUM>-<NUM>-alkylene, more preferably C<NUM>-<NUM>-alkylene, and still more preferably methylene.

In one embodiment, the alkylene in R<NUM> is fluoroalkylene, and preferably perfluoroalkylene.

In a preferred embodiment, R<NUM> is linear C<NUM>-<NUM>-perfluoroalkylene, and more preferably -CF<NUM>-.

The acid fluoride compound of formula (a) functions as a polymerization initiator in the reaction.

The acid fluoride compound of formula (a) is commercially available or can be produced by a method known to those skilled in the art.

In formula (b), R<NUM> is linear C<NUM>-<NUM>-fluoroalkylene, preferably an C<NUM>-<NUM>-fluoroalkylene, more preferably an C<NUM>-<NUM>-fluoroalkylene, and still more preferably C<NUM>-fluoroalkylene.

In a preferred embodiment, R<NUM> is CF<NUM>CF<NUM>CH<NUM> or CF<NUM>CF<NUM>CF<NUM>, preferably CF<NUM>CF<NUM>CH<NUM>.

In a preferred embodiment, the cyclic ether compound of formula (b) is tetrafluorooxetane.

The cyclic ether compound of formula (b) is cleaved between C and O to react with the acid fluoride compound of the above formula (a), resulting in the fluoropolyether group-containing compound of formula (A). That is, the compound of formula (b) forms a portion of R<NUM> of formula (A), which is a product.

The compound of formula (b) functions as a monomer in the reaction.

The compound of formula (b) is commercially available or can be produced by a method known to those skilled in the art.

The proportion of the compound of formula (a) to the compound of formula (b) can be appropriately set according to e.g. the molecular weight of the target compound, and for example, the molar ratio may be (<NUM>:<NUM>)-(<NUM>:<NUM>), preferably (<NUM>:<NUM>)-(<NUM>:<NUM>), and for example, (<NUM>:<NUM>)-(<NUM>:<NUM>).

The reaction between the compound of formula (a) and the compound of formula (b) is usually carried out in a solvent. Examples of the solvent include cyclic ethers such as tetrahydrofuran (THF), tetrahydropyran, and dioxane, cyclic ethers such as diethyl ether, diisopropyl ether, dibutyl ether, monoglyme, diglyme, triglyme, and tetraglyme, aromatic compounds such as HMPA (hexamethylphosphamide), dimethylpropylene (DMPU), tetramethylethylenediamine (TMEDA), toluene, xylene, and benzotrifluorides, amides such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone, and fluorine-containing organic solvents such as hexafluoropropylene, trichlorotrifluoroethane, <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-pentafluorobutane, m-xylene hexafluorolide, perfluorohexane, perfluorooctane, perfluorodimethylcyclohexane, perfluorodecalin, perfluoroalkyl ethanol, perfluorobenzene, perfluorotoluene, perfluoroalkylamine (such as fluorinert (trade name)), perfluoroalkyl ether, perfluorobutyl tetrahydrofuran, polyfluoroaliphatic hydrocarbon (AsahiKlin AC6000 (trade name)), hydrochlorofluorocarbon (such as AsahiKlin AK-<NUM> (trade name)), hydrofluoroether (such as Novec (trade name), HFE-<NUM> (trade name)), <NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>,<NUM>-heptafluorocyclopentane, fluorinated alcohol, perfluoroalkyl bromide, perfluoroalkyl iodide, perfluoropolyester (such as Krytox (trade name), Demnum (trade name), Fomblin (trade name)), <NUM>,<NUM>-bistrifluoromethylbenzene, <NUM>-(perfluoroalkyl)ethyl methacrylate, <NUM>-(perfluoroalkyl)ethyl acrylate, perfluoroalkyl ethylene, Freon 134a, and hexafluoropropene oligomers, or mixtures thereof.

The above reaction is preferably carried out in the presence of a catalyst. Examples of the catalyst include inorganic bases such as NaH, CaH<NUM>, LiH, LiAlH<NUM>, NaBH<NUM>, CstOBu, KtOBu, NatOBu, LitOBu, CsOH, KOH, NaOH, LiOH, Cs<NUM>CO<NUM>, K<NUM>CO<NUM>, Na<NUM>CO<NUM>, Li<NUM>CO<NUM>, CsHCO<NUM>, KHCO<NUM>, NaHCO<NUM>, LiHCO<NUM>, KF, CsF, tetra-n-butylammonium fluoride (TBAF), organic bases such as triethylamine, pyridine, N,N-dimethyl-<NUM>-aminopyridine (DMAP), diazabicycloundecene (DBU) and <NUM>,<NUM>-diazabicyclo[<NUM>. <NUM>]octane (DABCO), and organic lithium reagents such as nBuLi, tBuLi, and lithium diisopropylamide (LDA).

The reaction temperature of the above reaction is usually -<NUM> to <NUM>, preferably -<NUM> to <NUM>, and more preferably -<NUM> to <NUM>.

The reaction time of the above reaction may usually be <NUM> hour to <NUM> days, for example <NUM>-<NUM> days.

The end functional group of the compound of formula (A) can be converted into a desired functional group by an appropriate treatment. For example, the end functional group can be converted into COOR<NUM> by reacting alcohol HOR<NUM>, and the end functional group can be converted into e.g. CH<NUM>OH or CHO by reducing the terminal functional group, whereby the compound of formula (1a) or (1b) can be obtained.

Further, the compound of formula (A) can be fluorinated. For example, the hydrogen atom bonded to the carbon of the fluoropolyether group-containing compound can be fluorinated and converted into the perfluoropolyether group-containing compound.

The following Examples <NUM> and <NUM> describe the synthesis of compounds of the present invention. Reference Examples <NUM>-<NUM> describe the synthesis of compounds not claimed in the present invention.

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of diglyme, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> minutes under an ice bath. Subsequently, at <NUM> under the ice bath, <NUM> of <NUM>,<NUM>,<NUM>,<NUM>-tetrafluorooxetane was added dropwise from the dropping funnel to the reaction container over <NUM> minutes and stirred for <NUM> hours. Then, the ice bath was removed and the mixture was stirred for <NUM> hours. The obtained reaction solution was filtered under pressure with a <NUM> PTFE filter, and diglyme was evaporated to obtain compound A1. (Number-average molecular weight: <NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

<NUM>F-NMR assignment of compound A1
<CHM>.

Chemical shift is based on m-xylene hexafluoride standard (-<NUM> ppm)
a: <NUM> ppm, b: -<NUM> ppm, c: -<NUM> to -<NUM> ppm, d: -<NUM> to -<NUM> ppm, e: -<NUM> ppm, f: -<NUM> ppm.

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of diglyme, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> minutes under an ice bath. Subsequently, at <NUM> under the ice bath, <NUM> of <NUM>,<NUM>,<NUM>,<NUM>-tetrafluorooxetane was added dropwise from the dropping funnel to the reaction container over <NUM> minutes and stirred for <NUM> hours. Then, the ice bath was removed and the mixture was stirred for <NUM> hours. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes, and the mixture was stirred for <NUM> hours. After evaporating volatile contents from the reaction solution under reduced pressure, <NUM> of m-xylene hexafloride and <NUM> of water were added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound A2. (Number-average molecular weight: <NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

<NUM>F-NMR assignment of compound A2
<CHM>.

Chemical shift is based on m-xylene hexafluoride standard (-<NUM> ppm)
b: -<NUM> ppm, c: -<NUM> to -<NUM> ppm, d: -<NUM> ppm, e: - <NUM> ppm, f: -<NUM> ppm.

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. The obtained reaction solution was filtered under pressure with a <NUM> PTFE filter, and tetraglyme was evaporated to obtain compound B1 (COF and methyl ester). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

<NUM>F-NMR assignment of compound B1
<CHM>.

Chemical shift is based on m-xylene hexafluoride standard (-<NUM> ppm)
a: -<NUM> ppm, c: -<NUM> to -<NUM> ppm, d,e: -<NUM> to -<NUM> ppm, f: -<NUM> ppm, g: -<NUM> to -<NUM> ppm, h: <NUM> ppm.

To the obtained B1 reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. For separation and washing, <NUM> of m-xylene hexafloride and <NUM> of water were added, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B2 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

<NUM>F-NMR assignment of compound B2
<CHM>.

Chemical shift is based on m-xylene hexafluoride standard (-<NUM> ppm)
a: -<NUM> ppm, c: -<NUM> to -<NUM> ppm, d,e: -<NUM> to -<NUM> ppm, f: -<NUM> ppm, g: -<NUM> to -<NUM> ppm.

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at -<NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. For separation and washing, <NUM> of m-xylene hexafloride and <NUM> of water were added, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B3 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of potassium fluoride, <NUM> of tetraglyme, <NUM> of m-xylene hexafloride, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. The obtained reaction solution was filtered under pressure with a <NUM> PTFE filter, and tetraglyme was evaporated to obtain compound B4 (COF and methyl ester). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%, Mw / Mn = <NUM> (GPC)).

To the obtained B4 reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. For separation and washing, <NUM> of water was added, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B5 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of potassium fluoride, <NUM> of tetraglyme, <NUM> of m-xylene hexafloride, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at -<NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B6 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, <NUM> of m-xylene hexafloride, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B7 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, <NUM> of Novec <NUM> (manufactured by <NUM>), and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B8 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, <NUM> of Novec <NUM> (manufactured by <NUM>), and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B9 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of cesium fluoride, <NUM> of tetraglyme, <NUM> of <NUM>,<NUM>,<NUM>,<NUM>,<NUM>-pentafluorobutane, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B10 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of potassium fluoride, <NUM> of tetraglyme, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B11 (methyl ester at both ends). (Number-average molecular weight: <NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of potassium fluoride, <NUM> of tetraglyme, <NUM> of m-xylene hexafloride, and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B12 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

To a nitrogen-purged reaction container, <NUM> of potassium fluoride, <NUM> of tetraglyme, <NUM> of Novec <NUM> (manufactured by <NUM>), and <NUM> of methyl <NUM>,<NUM>,<NUM>-trifluoro-<NUM>-oxopropanoate were added, and the mixture was stirred at <NUM> for <NUM> hours. Subsequently, a total of <NUM> of hexafluoropropylene oxide was added in <NUM> increments over <NUM> minutes at <NUM>, and the mixture was then stirred. To the obtained reaction solution, <NUM> of methanol was added dropwise over <NUM> minutes at <NUM>, and the mixture was stirred for <NUM> hours. To the reaction solution, <NUM> of water was added for separation and washing, and <NUM> of magnesium sulfate was added to the extracted organic layer for drying. Volatile contents were evaporated from the resulting treated solution to obtain compound B13 (methyl ester at both ends). (Number-average molecular weight: <NUM>,<NUM> (NMR), initiation efficiency from the acid fluoride: <NUM>%).

Claim 1:
A compound, which is a fluoropolyether-containing compound of formula (1a) or (1b):

        Ra-R<NUM>-R<NUM>-Rb     (1a)

        Ra-R<NUM>-R<NUM>-Rb     (1b)

wherein
Ra, Rb each independently are COF, COOR<NUM>, CH<NUM>OH or CHO, wherein R<NUM> each independently is H or C<NUM>-<NUM>-alkyl optionally substituted with F;
R<NUM> is C<NUM>-<NUM>-alkylene optionally substituted with F;
and
R<NUM> is -R6a- (OR5a)n-O-, wherein R5a is linear C<NUM>-<NUM>-fluoroalkylene, R6a is linear C<NUM>-<NUM>-fluoroalkylene, and n is an integer of <NUM>-<NUM>,
provided that in formula (1a) Ra and Rb are not the same, and in formula (1b) R5a is CF<NUM>CF<NUM>CH<NUM> and R6a is CF<NUM>CH<NUM>.