Patent Description:
Perfluoro(poly)ether group-containing compounds are known to be capable of providing excellent water-repellency, oil-repellency, antifouling properties, heat resistance, low-temperature properties, oil resistance, solvent resistance, chemical resistance, lubricity, low-friction properties, abrasion resistance, mold releasability, and the like. Functional thin films containing a perfluoro(poly)ether group-containing compound is used in various substrates such as glass, plastics, fibers, metals, and construction materials. Fluorine-based elastomers containing a perfluoro(poly)ether group-containing compound are used as materials that are durable and reliable under severe environments of automobile, aircraft, semiconductor, aerospace, and like fields. In addition, perfluoro(poly)ether group-containing compounds can impart and exert excellent performance by being used as intermediate compounds or additives for resins such as acrylic resins, polyurethane, epoxy resins, polyester resins, and laminated resins, coating materials, cosmetics, and the like. Accordingly, research has been extensively carried out into procedures for synthesizing perfluoro(poly)ether group-containing compounds having various structures. In the synthesis of such a perfluoro(poly)ether group-containing compound, a perfluoro(poly)ether group-containing compound having a functional group is an important compound as a source material compound or an intermediate.

In general, the source material compound or the intermediate desirably has a higher purity. This is because a higher purity facilitates purification of the reaction product and, moreover, can reduce by-products or unidentified substances that can result from the reaction, and thus the target product having better performance can be obtained. The source material compound or the intermediate is usually produced as a mixture of a nonfunctional compound, a monofunctional compound having a functional group only at one terminal, and a bifunctional compound having a functional group at both terminals. Accordingly, to date, various studies have been conducted on a method for separating a desired source material compound or intermediate from a mixture of the source material compound or the intermediate.

For example, <CIT> (Patent Literature <NUM>) discloses a method for separating a nonfunctional species, a monofunctional species, and a bifunctional species from a mixture of a polymer constituting perfluoropolyoxyalkylene. <CIT> (Patent Literature <NUM>) discloses a method for separating bifunctional perfluoropolyether having -CH<NUM>OH terminals from a mixture with -CH<NUM>OH monofunctional perfluoropolyether.

<CIT> (Patent Literature <NUM>) discloses a process for separating bifunctional perfluoropolyethers having two methylol-terminations from mixtures with monofunctional PFPEs with one methylol-termination by adding an adsorbing solid phase, filtering the mixture, adding a PFPE mixture, filtering the mixture, and subsequent treatment of the thereby obtained solid phase separated with a polar solvent such as to obtain a liquid containing the PFPE having high functionality.

<CIT> (Patent Literature <NUM>) discloses a process for separating non-functional, monofunctional and bifunctional species in perfluoropolyoxyxalkylenes by subjecting said perfluoropolyoxyalkylenes to column chromatography using non-polar fluorinated solvents, either alone or in admixture with polar solvents, as eluents.

In Patent Literature <NUM>, the perfluoropolyoxyalkylene mixture adsorbed on a stationary phase is separated by elution using a <NUM>/<NUM> to <NUM>/<NUM> mixture of a nonpolar solvent and a polar solvent. In Patent Document <NUM>, the mixing ratio of the nonpolar solvent and the polar solvent is adjusted to carry out separation, and therefore investigations to determine an appropriate mixing ratio of the solvents are required. Moreover, the use of a mixed solvent is problematic in that the recovery of respective solvents after separation is difficult.

In Patent Literature <NUM>, separation is carried out by repeatedly performing the step of mixing an adsorbing solid phase with a perfluoropolyether mixture and stirring the mixture to adsorb the perfluoropolyether mixture that is rich in bifunctional perfluoropolyether onto the adsorbing solid phase, and then eluting the bifunctional perfluoropolyether from the adsorbing solid phase. In Patent Literature <NUM>, the operations need to be repeatedly performed and are thus troublesome. Moreover, other perfluoropolyether species in addition to the bifunctional perfluoropolyether are also adsorbed onto the adsorbing solid phase. It is therefore difficult to separate perfluoropolyether having high purity.

Accordingly, an object of the present invention is to provide a method capable of easily separating a mixture of a monofunctional compound and a bifunctional compound in a high-purity manner.

As a result of having conducted diligent research, the inventors found that in a method for separating a mixture containing perfluoro(poly)ether group-containing alcohol compounds by chromatography involving a mobile phase and a stationary phase, the use of one single solvent selected from the group consisting of hydrochlorofluorocarbons, hydrofluoroethers, fluorine-containing ester solvents, and fluorine-containing aromatic solvents as a mobile phase makes it possible to separate a perfluoro(poly)ether group-containing monoalcohol compound having a hydroxyl group at only one terminal and a perfluoro(poly)ether group-containing dialcohol compound having a hydroxyl group at both terminals, and the inventors accomplished the present invention.

According to the first aspect of the present invention, provided is:
A method for chromatographically separating a mixture containing a perfluoro(poly)ether group-containing monoalcohol compound represented by the following formula (<NUM>) and a perfluoro(poly)ether group-containing dialcohol compound represented by the following formula (<NUM>):.

According to the second aspect of the present invention, provided is:
A method for chromatographically separating a mixture containing:.

According to the present invention, the use of one solvent selected from the group consisting of hydrochlorofluorocarbons, hydrofluoroethers, fluorine-containing ester solvents, and fluorine-containing aromatic solvents as a mobile phase makes it possible to separate a perfluoro(poly)ether group-containing monoalcohol compound and a perfluoro(poly)ether group-containing dialcohol compound.

Below, the method of the present invention will now be described in detail.

The present invention relates to a method for separating a mixture containing a perfluoro(poly)ether group-containing monoalcohol compound and a perfluoro(poly)ether group-containing dialcohol compound into the respective compounds by chromatography involving a mobile phase and a stationary phase.

The perfluoro(poly)ether group-containing monoalcohol compound is a compound represented by the following formula (<NUM>), and the perfluoro(poly)ether group-containing dialcohol compound is a compound represented by the following formula (<NUM>).

The mixture to be separated by the method of the present invention contains the compounds represented by formulae (<NUM>) and (<NUM>). The mixture may contain two or more compounds represented by formula (<NUM>) and two or more compounds represented by formula (<NUM>).

In one embodiment, the mixture may further contain a perfluoro(poly)ether group-containing nonalcohol compound represented by the following formula (<NUM>).

In formulae (<NUM>) to (<NUM>), Pf is a divalent perfluoropolyether group.

In a preferable embodiment, Pf is a group represented by the following structural formula:
<CHM>
wherein a, b, c, and d are each independently an integer of <NUM> or <NUM> or more, and the sum of a, b, c, and d is at least <NUM>. Preferably, a, b, c, and d are each independently an integer of <NUM> or more and <NUM> or less, such as an integer of <NUM> to <NUM>, and more preferably each independently an integer of <NUM> to <NUM>. Preferably, the sum of a, b, c, and d is <NUM> or more, and more preferably <NUM> or more, such as <NUM> or more and <NUM> or less. The occurrence order of the respective repeating units in parentheses with the subscript a, b, c or d is not limited in the formula. Among these repeating units, -(OC<NUM>F<NUM>)- may be any of -(OCF<NUM>CF<NUM>CF<NUM>CF<NUM>)-, - (OCF(CF<NUM>)CF<NUM>CF<NUM>)-, -(OCF<NUM>CF(CF<NUM>)CF<NUM>)-, -(OCF<NUM>CF<NUM>CF(CF<NUM>))-, - (OC(CF<NUM>)<NUM>CF<NUM>)-, -(OCF<NUM>C(CF<NUM>)<NUM>)-, -(OCF(CF<NUM>)CF(CF<NUM>))-, - (OCF(C<NUM>F<NUM>)CF<NUM>)-, and -(OCF<NUM>CF(C<NUM>F<NUM>))-, and is preferably - (OCF<NUM>CF<NUM>CF<NUM>CF<NUM>)-. -(OC<NUM>F<NUM>)- may be any of -(OCF<NUM>CF<NUM>CF<NUM>)-, - (OCF(CF<NUM>)CF<NUM>)-, and -(OCF<NUM>CF(CF<NUM>)) -, and is preferably - (OCF<NUM>CF<NUM>CF<NUM>)-. -(OC<NUM>F<NUM>)- may be any of -(OCF<NUM>CF<NUM>)- and - (OCF(CF<NUM>))-, and is preferably -(OCF<NUM>CF<NUM>)-.

In one embodiment, Pf is -(OC<NUM>F<NUM>)b-, wherein b is an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, is preferably -(OCF<NUM>CF<NUM>CF<NUM>)b-, wherein b is an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, or - (OCF(CF<NUM>)CF<NUM>)b-, wherein b is an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, and is more preferably -(OCF<NUM>CF<NUM>CF<NUM>)b-, wherein b is an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>.

In another embodiment, Pf is -(OC<NUM>F<NUM>)a-(OC<NUM>F<NUM>)b-(OC<NUM>F<NUM>)c-(OCF<NUM>)d-, wherein a and b are each independently an integer of <NUM> or more and <NUM> or less, c and d are each independently an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, and the occurrence order of the respective repeating units in parentheses with the subscript a, b, c or d is not limited in the formula, and is preferably -(OCF<NUM>CF<NUM>CF<NUM>CF<NUM>)a-(OCF<NUM>CF<NUM>CF<NUM>)b-(OCF<NUM>CF<NUM>)c-(OCF<NUM>)d-. In one embodiment, Pf may be -(OC<NUM>F<NUM>)c-(OCF<NUM>)d-, wherein c and d are each independently an integer of <NUM> or more and <NUM> or less, preferably <NUM> to <NUM>, and more preferably <NUM> to <NUM>, and the occurrence order of the respective repeating units in parentheses with the subscript c or d is not limited in the formula.

In yet another embodiment, Pf is a group represented by -(R<NUM>-R<NUM>)j- wherein R<NUM> is OCF<NUM> or OC<NUM>F<NUM> and preferably OC<NUM>F<NUM>. In a preferable embodiment, Pf is a group represented by -(OC<NUM>F<NUM>-R<NUM>)f-, wherein R<NUM> is a group selected from OC<NUM>F<NUM>, OC<NUM>F<NUM>, and OC<NUM>F<NUM>, or is a combination of <NUM> or <NUM> groups independently selected from these groups. Examples of the combination of <NUM> or <NUM> groups independently selected from OC<NUM>F<NUM>, OC<NUM>F<NUM>, and OC<NUM>F<NUM> include, but are not limited to, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, - OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>-, - OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, - OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, - OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, -OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-, and - OC<NUM>F<NUM>OC<NUM>F<NUM>OC<NUM>F<NUM>-. f is an integer of <NUM> or more and <NUM> or less, and preferably an integer of <NUM> to <NUM>. In the formulae, OC<NUM>F<NUM>, OC<NUM>F<NUM>, and OC<NUM>F<NUM> may be either linear or branched, and is preferably linear. In this embodiment, Pf is preferably -(OC<NUM>F<NUM>-OC<NUM>F<NUM>)f- or -(OC<NUM>F<NUM>-OC<NUM>F<NUM>)f-.

The number average molecular weight of Pf in formulae (<NUM>) to (<NUM>) is preferably <NUM> to <NUM>,<NUM>, more preferably <NUM>,<NUM> to <NUM>,<NUM>, and even more preferably <NUM>,<NUM> to <NUM>,<NUM>. The number average molecular weight is a value measured by <NUM>F-NMR.

In formulae (<NUM>) and (<NUM>), the A group each independently represents an R<NUM>- group, an R<NUM>-O- group, an R<NUM>O-CH<NUM>-R<NUM>- group, or an R<NUM>O-CH<NUM>-R<NUM>-O- group.

R<NUM> each independently represents an alkyl group. This alkyl group may have a substituent. The substituent is, for example, a halogen atom such as a fluorine atom or a chlorine atom, an amino group, or a sulfonyl group, preferably a halogen atom, and more preferably a fluorine atom or a chlorine atom.

In a preferable embodiment, the alkyl group may be a C<NUM>-<NUM> perfluoroalkyl group or R<NUM>-(Cg+<NUM>F<NUM>+<NUM>), and preferably a C<NUM>-<NUM> perfluoroalkyl group or a group represented by R<NUM>-CF<NUM>(CF<NUM>)g-, wherein g is an integer of <NUM> or more and <NUM> or less, preferably an integer of <NUM> to <NUM>, more preferably an integer of <NUM> to <NUM>, and even more preferably an integer of <NUM> to <NUM>.

R<NUM> represents a hydrogen atom or a halogen atom other than fluorine. The halogen atom other than fluorine may preferably be a chlorine atom or an iodine atom, and more preferably a chlorine atom. R<NUM> is preferably a hydrogen atom or a chlorine atom. In one embodiment, R<NUM> is a hydrogen atom. In another embodiment, R<NUM> is a chlorine atom.

The C<NUM>-<NUM> perfluoroalkyl group may be a linear or branched perfluoroalkyl group having <NUM> to <NUM> carbon atoms, preferably a linear or branched perfluoroalkyl group having <NUM> to <NUM> carbon atoms, more preferably a perfluoroalkyl group having <NUM> to <NUM> carbon atoms, and more specifically -CF<NUM>, - CF<NUM>CF<NUM>, or -CF<NUM>CF<NUM>CF<NUM>.

In a preferable embodiment, R<NUM> may be a C<NUM>-<NUM> perfluoroalkyl group, HCF<NUM>(CF<NUM>)g-, or ClCF<NUM>(CF<NUM>)g-, wherein g may be an integer of <NUM> or more and <NUM> or less.

R<NUM> represents an alkyl group. R<NUM> is preferably a C<NUM>-<NUM> alkyl group. The C<NUM>-<NUM> alkyl group is, for example, a linear or branched C<NUM>-<NUM> alkyl group. Specific examples of the C<NUM>-<NUM> alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a <NUM>-butyl group, an isobutyl group, and a t-butyl group. R<NUM> is more preferably a methyl group or an ethyl group. These alkyl groups may have a substituent. The substituent is, for example, a halogen atom such as a fluorine atom or a chlorine atom.

R<NUM> each independently represents a divalent organic group containing <NUM> to <NUM> carbon atoms.

Specific examples of the "divalent organic group containing <NUM> to <NUM> carbon atoms" include a C<NUM>-<NUM> alkylene group, a C<NUM>-<NUM> fluoroalkylene group, or a C<NUM>-<NUM> perfluoroalkylene group.

Examples of the C<NUM>-<NUM> alkylene group include -CH<NUM>-, - C<NUM>H<NUM>-, -C<NUM>H<NUM>-, and -C<NUM>H<NUM>-. Here, -C<NUM>H<NUM>- and -C<NUM>H<NUM>- may be linear or branched. The C<NUM>-<NUM> fluoroalkylene group may be a group in which some hydrogen atoms of the above C<NUM>-<NUM> alkylene group are substituted with fluorine atoms. The C<NUM>-<NUM> perfluoroalkylene group may be a group in which all hydrogen atoms of the above C<NUM>-<NUM> alkylene group are substituted with fluorine atoms.

R<NUM> is preferably each independently -CF<NUM>-, -CF<NUM>CF<NUM>-, - CH<NUM>CF<NUM>-, -CF<NUM>CH<NUM>-, -CF<NUM>CF<NUM>CF<NUM>-, -CF (CF<NUM>)CF<NUM>-, -CF (CF<NUM>)CH<NUM>-, - CF<NUM>CF<NUM>CH<NUM>-, -CH<NUM>CF<NUM>CF<NUM>-, or -CH<NUM>CF(CF<NUM>)-.

In formulae (<NUM>) and (<NUM>), Z each independently represents an -R<NUM>-CH<NUM>OH group or an -O-R<NUM>-CH<NUM>OH group.

R<NUM> represents a bond or a divalent organic group containing <NUM> to <NUM> carbon atoms. The "divalent organic group containing <NUM> to <NUM> carbon atoms" is as defined in connection with R<NUM>.

As used herein, the "bond" means a simple bond not having an atom, i.e., a single bond. For example, when R<NUM> is a bond, the Z group in the case of being an -O-R<NUM>-CH<NUM>OH group represents -O-CH<NUM>OH group.

R<NUM> is preferably each independently -CF<NUM>-, -CF<NUM>CF<NUM>-, - CH<NUM>CF<NUM>-, -CF<NUM>CH<NUM>-, -CF<NUM>CF<NUM>CF<NUM>-, -CF (CF<NUM>)CF<NUM>-, -CF(CF<NUM>)CH<NUM>-, - CF<NUM>CF<NUM>CH<NUM>-, -CH<NUM>CF<NUM>CF<NUM>-, or -CH<NUM>CF(CF<NUM>)-, and is preferably - CF<NUM>-, -CF<NUM>CF<NUM>-, or -CF<NUM>CF<NUM>CF<NUM>-.

In a preferable embodiment, Z is each independently a -CH<NUM>OH group, a -CF<NUM>-CH<NUM>OH group, a -CF<NUM>CF<NUM>-CH<NUM>OH group, or a -CF<NUM>CF<NUM>CF<NUM>-CH<NUM>OH group.

The compounds represented by formulae (<NUM>) to (<NUM>) are preferably <NUM>,<NUM> to <NUM>,<NUM>, more preferably <NUM>,<NUM> to <NUM>,<NUM>, and even more preferably <NUM>,<NUM> to <NUM>,<NUM>.

The perfluoro(poly)ether group-containing nonalcohol compound represented by formula (<NUM>) may be, for example, compounds shown below.

In the formulae, Pf, R<NUM>, R<NUM>, and R<NUM> are as defined above.

The perfluoro(poly)ether group-containing monoalcohol compound represented by formula (<NUM>) may be, for example, compounds shown below.

In the formulae, Pf, R<NUM>, R<NUM>, R<NUM>, and R<NUM> are as defined above.

The perfluoro(poly)ether group-containing dialcohol compound represented by formula (<NUM>) may be, for example, compounds shown below.

In the formula, Pf and R<NUM> are as defined above.

The mixture of compounds represented by any of formulae (<NUM>) to (<NUM>) may be produced by, but not limited to, the following reactions.

The above reactions can be carried out under reaction conditions that are commonly used by those skilled in the art.

The separation method of the present invention is carried out by separating the mixture by chromatography involving a stationary phase and a mobile phase.

Examples of the chromatography include, but are not limited to, column chromatography and thin layer chromatography. Column chromatography is preferably used, and flash column chromatography is particularly preferably used.

The stationary phase used in the chromatography is preferably selected from the group consisting of aluminum oxide, silica gel, magnesium oxide, aluminum silicate, magnesium silicate, chemically modified silica gel, and diatomaceous earth.

The stationary phase is more preferably silica gel. Examples of silica gel include unmodified silica gel, amino group-containing silica gel, and cyano group-containing silica gel.

Commercially available silica gel can be used. Examples of commercially available silica gel include Chromatorex (PSQ-100B) manufactured by Fuji Silysia Chemical Ltd. , Wakogel C-<NUM> manufactured by Wako Pure Chemical Industries, Ltd. , and <NUM> Silica Gel <NUM> manufactured by Merck.

The amount of the stationary phase to be used is suitably selected according to the compound to be separated, the mobile phase to be used, the type of chromatography, and the like. Preferably, the stationary phase is used in an amount in terms of weight equal to or greater than the amount of the mixture to be separated. When the molecular weight of the compound to be separated is relatively small, a larger amount of the stationary phase is preferably used.

In the method of the present invention, first a mixture containing the compound represented by formula (<NUM>) and the compound represented by formula (<NUM>) is adsorbed onto the stationary phase. The adsorption method is not limited, and may be a method commonly carried out with respect to chromatography.

Next, the compound represented by formula (<NUM>) is eluted by allowing a mobile phase to pass through the stationary phase on which the mixture is adsorbed to separate the compound represented by formula (<NUM>) from the compound represented by formula (<NUM>).

The mobile phase used in the elution of the compound represented by formula (<NUM>) is one solvent selected from the group consisting ofhydrochlorofluorocarbons, hydrofluoroethers, fluorine-containing ester solvents, and fluorine-containing aromatic solvents. The above one solvent means a substantially single solvent. The term "substantially single" means that the presence of impurities that cannot be removed or are hardly removable is allowed.

Examples of the hydrochlorofluorocarbons include hydrochlorofluorocarbons having <NUM> to <NUM> carbon atoms, such as HCFC-<NUM> (CF<NUM>CF<NUM>CHCl<NUM>, CClF<NUM>CF<NUM>CHClF). A preferable hydrochlorofluorocarbon is HCFC-<NUM>.

Examples of the hydrofluoroethers include Novec (TM) <NUM> (C<NUM>F<NUM>OCH<NUM>), Novec (TM) <NUM> (C<NUM>F<NUM>OCH<NUM>), Novec (TM) <NUM> (C<NUM>F<NUM>OC<NUM>H<NUM>), Novec (TM) <NUM> (C<NUM>F<NUM>CF(OCH<NUM>)C<NUM>F<NUM>), and Novec (TM) <NUM> IPA. A preferable hydrofluoroether is C<NUM>F<NUM>CF(OCH<NUM>)C<NUM>F<NUM> (perfluorohexylmethylether).

Examples of the fluorine-containing ester solvents include fluorine-containing esters having <NUM> to <NUM> carbon atoms, such as ethyl trifluoroacetate, methyl trifluoroacetate, CF<NUM>CF<NUM>COOCH<NUM>, and CF<NUM>CF<NUM>COOCH<NUM>CH<NUM>.

Examples of the fluorine-containing aromatic solvents include fluorine-containing aromatic solvents having <NUM> to <NUM> carbon atoms, such as meta-xylenehexafluoride (m-XHF), perfluorobenzene, trifluorobenzene, and monofluorobenzene. A preferable fluorine-containing aromatic solvent is meta-xylenehexafluoride.

In a preferable embodiment, the single solvent forming the mobile phase to be used in the elution of the compound represented by formula (<NUM>) is m-xylene hexafluoride, perfluorobenzene, perfluorohexyl methyl ether, perfluorobutyl ethyl ether, perfluorobutyl methyl ether, HCFC-<NUM>, or ethyl trifluoroacetate.

In the elution of the compound represented by formula (<NUM>), the temperature of the stationary phase may preferably be -<NUM> or higher and <NUM> or lower, more preferably <NUM> to <NUM>, and further preferably <NUM> to <NUM>, such as room temperature (<NUM>).

In one embodiment, after the compound represented by formula (<NUM>) is eluted, the temperature of the stationary phase is increased to elute the compound represented by formula (<NUM>).

The mobile phase to be used in the elution of the compound represented by formula (<NUM>) is one solvent selected from the group consisting of hydrochlorofluorocarbons, hydrofluoroethers, fluorine-containing ester solvents, and fluorine-containing aromatic solvents.

In one embodiment, the mobile phase to be used in the elution of the compound represented by formula (<NUM>) may be the same as the solvent used in the elution of the compound represented by formula (<NUM>).

In the elution of the compound represented by formula (<NUM>), the temperature of the stationary phase may preferably be <NUM> or higher and <NUM> or lower, more preferably <NUM> to <NUM>, and further preferably <NUM> to <NUM>.

In one embodiment, when the mixture further contains a compound represented by formula (<NUM>), the compound represented by formula (<NUM>) is eluted before the compound represented by formula (<NUM>) is eluted.

The mobile phase to be used in the elution of the compound represented by formula (<NUM>) is not limited, and is a nonpolar solvent or a low-polarity solvent, and preferably a fluorine-containing alkane solvent.

Examples of the fluorine-containing alkane solvent include perfluoroalkanes having <NUM> to <NUM> carbon atoms, such as perfluorohexane (PFH), perfluorooctane perfluoroundecane, and perfluorododecane. A preferable fluorine-containing alkane solvent is perfluorohexane.

In one embodiment, the present invention may be a method for chromatographically separating a mixture containing:.

In one embodiment, the chromatographic separation is carried out by column chromatography. Specifically, the mixture is directly, or after mixed with a solvent, placed on a stationary phase with which a column is packed, and the mixture is adsorbed onto the stationary phase. In this case, the solvent to be used is preferably a solvent to be used as a mobile phase. Then, the solvent that serves as a mobile phase is poured from the column top, and fractions obtained from the bottom of the column are collected.

In a preferable embodiment, the column chromatography is carried out under pressure, e.g., under pressure of an inert gas such as nitrogen or argon. Preferably a pressure of <NUM> MPa or more and <NUM> MPa or less, and more preferably <NUM> MPa to <NUM> MPa, is applied.

The method of the present invention described above can be used in the production of the compound represented by formula (<NUM>) or the compound represented by formula (<NUM>).

The mixture of the compound represented by formula (<NUM>) and the compound represented by formula (<NUM>) in the above production method may be produced by, but not limited to, the following reactions.

The present invention will now be described in more detail below by way of Examples, but the present invention is not limited thereto.

In Examples, the occurrence order of the respective repeating units (CF<NUM>O), (CF<NUM>CF<NUM>O), (CF<NUM>CF<NUM>CF<NUM>O), and (CF<NUM>CF<NUM>CF<NUM>CF<NUM>O) constituting perfluoropolyether is not limited. Also, all chemical formulae shown below represent the average compositions.

A stationary phase was prepared by introducing a mixture of perfluorohexane (<NUM>) and silica gel (<NUM>) into a column having a diameter of <NUM> and a height of <NUM> and then allowing perfluorohexane (<NUM>) to flow. Thereafter, a mixture of perfluoropolyether group-containing compounds represented by the following structure (<NUM>) (<NUM>, number average molecular weight (Mn) = <NUM>, nonalcohol compound <NUM> wt%, monoalcohol compound <NUM> wt%, dialcohol compound <NUM> wt%) was diluted with perfluorohexane (<NUM>) and adsorbed onto silica gel at the column top.

A-(CF<NUM>O)k(CF<NUM>CF<NUM>O)l(CF<NUM>CF<NUM>CF<NUM>O)m(CF<NUM>CF<NUM>CF<NUM>CF<NUM>O)n-A'     (I).

wherein A and A' are any of -CF<NUM>Cl, -CF<NUM>, -CF<NUM>CF<NUM>, and - CH<NUM>OH; k is <NUM>; l is <NUM>; m is <NUM>; and n is <NUM>.

The fractionation operation was carried out according to the following procedure.

The analysis demonstrated that in the perfluoropolyether group-containing compounds (<NUM>) obtained by concentrating this recovered product, the monoalcohol compound was <NUM> wt%, and the dialcohol compound was <NUM> wt%.

A stationary phase was prepared by introducing a mixture of perfluorohexane (<NUM>) and silica gel (<NUM>) into a column having a diameter of <NUM> and a height of <NUM> and then allowing perfluorohexane (<NUM>) to flow. Thereafter, a mixture of compounds represented by the above structure (<NUM>) (<NUM>, number average molecular weight (Mn) = <NUM>, nonalcohol compound <NUM> wt%, monoalcohol compound <NUM> wt%, dialcohol compound <NUM> wt%) was diluted with perfluorohexane (<NUM>) and adsorbed onto silica gel at the column top.

A stationary phase was prepared by introducing a mixture of perfluorohexane (<NUM>) and silica gel (<NUM>) into a column having a diameter of <NUM> and a height of <NUM> and then allowing perfluorohexane (<NUM>) to flow. Thereafter, a mixture of compounds represented by the above structure (<NUM>) (<NUM>, number average molecular weight (Mn) = <NUM>, nonalcohol compound <NUM> wt%, monoalcohol compound <NUM> wt%, dialcohol compound <NUM> wt%) (wherein k is <NUM>, l is <NUM>, m is <NUM>, and n is <NUM>) was diluted with perfluorohexane (<NUM>) and adsorbed onto silica gel at the column top.

A stationary phase was prepared by introducing a mixture of perfluorohexane (<NUM>) and silica gel (<NUM>) into a column having a diameter of <NUM> and a height of <NUM> and then allowing perfluorohexane (<NUM>) to flow. Thereafter, a mixture of compounds represented by the above structure (<NUM>) (<NUM>, number average molecular weight (Mn) = <NUM>, nonalcohol compound <NUM> wt%, monoalcohol compound <NUM> wt%, dialcohol compound <NUM> wt%) (wherein m is <NUM>; and k, l, and n are <NUM>) was diluted with perfluorohexane (<NUM>) and adsorbed onto silica gel at the column top.

The stationary phase of thin layer chromatography provided was a silica gel thin layer plate (length <NUM>, width <NUM>; <NUM> TLC Aluminum Sheet Silica Gel 60F254 manufactured by Merck). A sample was obtained by diluting any of the following mixtures (A), (B), and (C) of perfluoropolyether group-containing compounds with perfluorohexane. Then, <NUM> to <NUM>µl of the sample was spotted at a place <NUM> from the lower end of the silica gel thin layer plate using a glass microcapillary, and dried. This spotted place was determined as the starting point (origin) of development.

Solvents (a) to (k) shown in the following table were added as developing solvents to a thin layer chromatography developing vessel to a depth of <NUM> to <NUM>, and the developing vessel was allowed to stand still until the vapor of the developing solvent saturated in the developing vessel. Then, the thin layer plate that had been spotted with a sample solution was gently placed in the developing vessel such that the origin was not directly submerged in the developing solvent, and the developing vessel was capped and allowed to stand still until the distal end of the solvent ascending the thin layer plate reached a place about <NUM> from the top end of the thin layer plate. Then, the thin layer plate was removed from the developing vessel, and thereafter the developing solvent was sufficiently dried. The dried thin layer plate was immersed in a <NUM>% aqueous potassium permanganate solution and thereafter thermally dried.

Immersing the thin layer plate in a <NUM>% aqueous potassium permanganate solution made the entire thin layer plate reddish purple. Thereon, the perfluoropolyether group-containing monoalcohol (one terminal) and the perfluoropolyether group-containing dialcohol (both terminals) appeared as white spots. The centers of the white spots of the perfluoropolyether group-containing monoalcohol and the perfluoropolyether group-containing dialcohol were marked, and the distance from the origin to the center of the spot was divided by the distance of solvent development to obtain an Rf value. It can be said that separation occurred if the Rf values of the both-terminal component and the one-terminal component were different. It can also be said that the smaller the value of Rf (both-terminal component)/Rf (one-terminal component) is, the greater the separability is.

In Examples <NUM> to <NUM> in which solvents a to g were used, the one-terminal component and the both-terminal component were separated on the TLC plate. In particular, solvents a, c, and d resulted in a small Rf (both-terminal)/Rf (one-terminal) value, and is more suitable for separating the both-terminal component and the one-terminal component. On the other hand, in Comparative Examples <NUM> to <NUM> in which solvents h to k were used, neither the one-terminal component nor the both-terminal component moved. Solvents h to k are considered as having low polarity or insufficient separability because they do not dissolve perfluoropolyether group-containing alcohols.

When a mixed solvent of m-XHF and methanol was used in the above-described manner, the initial fractions were rich in monofunctional component, but the bifunctional component gradually increased. That is to say, fractions were obtained in which the monofunctional component and the bifunctional component were not separated (Fr <NUM> to <NUM> in particular). On the other hand, as described above, in the Examples in which a single solvent was used, the monofunctional component and the bifunctional component are favorably separated. Furthermore, since a mixed solvent is used in Comparative Example <NUM>, it is difficult to individually isolate m-XHF and methanol from the obtained fractions, which is disadvantageous from the viewpoint of reuse.

Claim 1:
A method for chromatographically separating a mixture comprising
- a perfluoro(poly)ether group-containing monoalcohol compound of the formula A-Pf-Z (<NUM>), and
- a perfluoro(poly)ether group-containing dialcohol compound of the formula Z-Pf-Z (<NUM>):
wherein
Pf is a divalent perfluoropolyether group,
A is R<NUM>-, R<NUM>-O-, R<NUM>O-CH<NUM>-R<NUM>- or R<NUM>O-CH<NUM>-R<NUM>-O-, wherein R<NUM> is alkyl, R<NUM> is alkyl, and R<NUM> is a divalent C<NUM>-<NUM>-organic group,
Z each independently is -R<NUM>-CH<NUM>OH or -O-R<NUM>-CH<NUM>OH, wherein R<NUM> is a bond or a divalent C<NUM>-<NUM>-organic group,
the method comprising
- adsorbing the mixture onto a stationary phase, and
- eluting the compound (<NUM>) by a mobile phase, the mobile phase being one single solvent selected from hydrochlorofluorocarbons, hydrofluoroethers, fluorine-containing ester solvents, and fluorine-containing aromatic solvents, to separate the compound (<NUM>) from the compound (<NUM>).