JP2023034081A - Fluorine-containing cyclic sulfonyl imide salt - Google Patents

Abstract

To provide a fluorine-containing cyclic sulfonyl imide salt having high heat resistance and low metal corrosiveness.SOLUTION: A fluorine-containing cyclic sulfonyl imide salt is represented by the general formula (1) {where each R may be the same or different to represent a fluorine atom or a trifluoromethyl group, n is an integer of 1-4, and M is Li, Na or K}. T1/T2 is 500 or more, which is the ratio between the sum T1 of integral values of peaks of the compound represented by the general formula (1) in 19F-NMR and the sum T2 of integral values of peaks of impurities characterized by appearing in the region of -115 ppm to -125 ppm as a single or plurality of doublet peak(s).SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to fluorine-containing cyclic sulfonylimide salts useful as antistatic agents, ion-conducting materials such as organic electrolytes, and flame retardants.

Fluorine-containing sulfonylimide salts such as N,N-bis(trifluoromethanesulfonyl)imide and bis(fluorosulfonyl)imide, and their derivatives are known to be compounds useful as ion-conducting materials and flame retardants. (For example, see Non-Patent Document 1 below).
By the way, as a method for producing a fluorine-containing sulfonylimide _salt , _{FO2SCF2CF2SO2F} synthesized by an electrolytic coupling reaction of _FSO2CF2COOH is _reacted with ammonia to obtain an ammonium salt _of a fluorine-containing cyclic _{sulfonylimide} . After obtaining (cyclization reaction), a method of reacting with an alkali metal hydroxide or carbonate (cation exchange reaction) is known (see Patent Document 1 below).

WO2006/106960

Asahi Glass Research Report Vol.60 (2010) pp.13-21

｛式中、Ｒは、それぞれ、同一であっても異なっていてもよく、フッ素原子又はトリフルオロメチル基であり、ｎは、１～４の整数であり、そしてＭは、Ｌｉ、Ｎａ又はＫである。｝で表される含フッ素環状スルホニルイミド塩（以下、本書中、該化合物群の内の１の化合物を含めて化合物（１）ともいう。）を製造した場合、¹⁹Ｆ－ＮＭＲにおいて－１１５ｐｐｍ～－１２５ｐｐｍの領域に単一の又は複数の二重線ピークとして現れることに特徴的なフッ素含有不純物が混入し、結果として化合物（１）の所望の耐熱特性が得られず、更に製造工程、及び最終製品として金属部材と接触した際に金属表面を腐食することで帯電防止剤、イオン電導材料や難燃剤等としての利用が制限される。 Patent Document 1 describes that the reaction crude product containing FO ₂ SCF ₂ CF ₂ SO ₂ F synthesized by the electrolytic coupling reaction may be purified by post-treatment such as distillation. No specific post-treatment for reducing the content of specific by-products contained in the fluorine-containing sulfonylimide salt, which is the product, is neither described nor suggested.
According to Patent Document 1, the following general formula (1):

{wherein each R may be the same or different and is a fluorine atom or a trifluoromethyl group, n is an integer of 1 to 4, and M is Li, Na or K is. } (hereinafter also referred to as compound (1), including one compound in the compound group) represented by ¹⁹ F-NMR -115 ppm ~ Fluorine-containing impurities characteristically appearing as single or multiple doublet peaks in the region of −125 ppm are mixed in, resulting in the failure to obtain the desired heat resistance properties of compound (1), further manufacturing steps, and As a final product, it corrodes the metal surface when it comes into contact with a metal member, which limits its use as an antistatic agent, an ion-conducting material, a flame retardant, and the like.

In view of the above circumstances, the problem to be solved by the present invention is to provide a fluorine-containing cyclic sulfonylimide salt having high heat resistance and low metal corrosiveness.

The inventors of the present invention, as a result of intensive studies and repeated experiments in order to solve the above problems, have found that an alkali metal salt of a fluorine-containing cyclic sulfonimide with reduced specific impurities can reduce metal corrosiveness and has excellent heat resistance. This unexpected finding led to the completion of the present invention.

｛式中、Ｒは、それぞれ、同一であっても異なっていてもよく、フッ素原子又はトリフルオロメチル基であり、ｎは、１～４の整数であり、そしてＭは、Ｌｉ、Ｎａ又はＫである。｝で表される含フッ素環状スルホニルイミド塩であって、¹⁹Ｆ－ＮＭＲにおける前記一般式（１）で表される化合物のピークの積分値の和Ｔ１と、－１１５ｐｐｍ～－１２５ｐｐｍの領域に単一の又は複数の二重線ピークとして現れることに特徴的な不純物のピークの積分値の和Ｔ２、との比Ｔ１／Ｔ２が、５００以上であることを特徴とする、含フッ素環状スルホニルイミド塩。
［２］前記一般式（１）中、ｎが１～３の整数である、前記［１］に記載の含フッ素環状スルホニルイミド塩。
［３］前記一般式（１）中、ｎが２である、前記［２］に記載の含フッ素環状スルホニルイミド塩。
［４］前記一般式（１）中、Ｒがフッ素原子である、前記［１］～［３］のいずれかに記載の含フッ素環状スルホニルイミド塩。
［５］前記一般式（１）中、ＭはＬｉである、前記［１］～［４］のいずれかに記載の含フッ素環状スルホニルイミド塩。
［６］以下の構造式：

で表される、前記［１］～［５］のいずれかに記載の含フッ素環状スルホニルイミド塩。 That is, the present invention is as follows.
[1] the following general formula (1):

{wherein each R may be the same or different and is a fluorine atom or a trifluoromethyl group, n is an integer of 1 to 4, and M is Li, Na or K is. }, wherein the sum T1 of the integrated values of the peaks of the compound represented by the general formula (1) in ¹⁹ F-NMR and the unit in the region of -115 ppm to -125 ppm A fluorine-containing cyclic sulfonylimide salt, characterized in that the ratio T1/T2 to the sum T2 of integrated values of impurity peaks characterized by appearing as one or more doublet peaks is 500 or more. .
[2] The fluorine-containing cyclic sulfonylimide salt according to [1] above, wherein n is an integer of 1 to 3 in general formula (1).
[3] The fluorine-containing cyclic sulfonylimide salt according to [2], wherein n is 2 in the general formula (1).
[4] The fluorine-containing cyclic sulfonylimide salt according to any one of [1] to [3], wherein R is a fluorine atom in general formula (1).
[5] The fluorine-containing cyclic sulfonylimide salt according to any one of [1] to [4], wherein M is Li in general formula (1).
[6] the following structural formula:

The fluorine-containing cyclic sulfonylimide salt according to any one of [1] to [5] above, represented by

INDUSTRIAL APPLICABILITY The fluorine-containing cyclic sulfonylimide salt according to the present invention has high heat resistance and low metal corrosiveness, so that it can be used for applications in contact with various metal members in a wide temperature range.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail.
However, the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

｛式中、Ｒは、それぞれ、同一であっても異なっていてもよく、フッ素原子又はトリフルオロメチル基であり、ｎは、１～４の整数であり、そしてＭは、Ｌｉ、Ｎａ又はＫである。｝で表される含フッ素環状スルホニルイミド塩であって、¹⁹Ｆ－ＮＭＲにおける前記一般式（１）で表される化合物のピークの積分値の和Ｔ１と、－１１５ｐｐｍ～－１２５ｐｐｍの領域に単一の又は複数の二重線ピークとして現れることに特徴的な不純物のピークの積分値の和Ｔ２、との比Ｔ１／Ｔ２が、５００以上であることを特徴とする含フッ素環状スルホニルイミド塩である。
以下、化合物（１）について詳細に説明する。 One embodiment of the present invention is represented by the following general formula (1):

{wherein each R may be the same or different and is a fluorine atom or a trifluoromethyl group, n is an integer of 1 to 4, and M is Li, Na or K is. }, wherein the sum T1 of the integrated values of the peaks of the compound represented by the general formula (1) in ¹⁹ F-NMR and the unit in the region of -115 ppm to -125 ppm A fluorine-containing cyclic sulfonylimide salt characterized in that the ratio T1/T2 of the sum T2 of the integrated values of peaks of impurities characterized by appearing as one or more doublet peaks is 500 or more. be.
The compound (1) will be described in detail below.

で表される化合物が挙げられ、好ましい。 <Fluorinated Cyclic Sulfonylimide Salt (Compound (1))>
In the general formula (1), n is an integer of 1 to 4 from the viewpoint of easy availability or production and excellent economic efficiency, and from the same viewpoint, it is preferably an integer of 1 to 3, 1 or Two is more preferred, and two is most preferred.
Each R may be the same or different, and is a fluorine atom or a trifluoromethyl group, most preferably a fluorine atom, from the viewpoints of availability or easy production and excellent economic efficiency.
M is Li, Na or K (that is, an alkali metal ion), preferably Li or Na, and most preferably Li, from the viewpoint of ease of availability or production and excellent economic efficiency.
Compound (1) may be used singly or in combination.
Specific examples of compound (1) include the following structural formula:

A compound represented by is preferred.

The fluorine-containing cyclic sulfonylimide salt has the sum T1 of the integrated values of the peaks of the compound (1) in ¹⁹ F-NMR and fluorine-containing impurities, especially single or multiple doublets in the region of −115 ppm to −125 ppm It is preferable that the ratio T1/T2 to the sum T2 of the integrated values of impurity peaks, which is characteristic of appearing as peaks, is 500 or more. Although the specific chemical structure of the impurity having such characteristics is not clear, it appears as a doublet peak, so for example H--CF ₂ --X--Y (X is a linking group having no hydrogen and fluorine; Y is expected to be a fluorine-containing impurity such as a non-limiting functional group), which has a protic hydrogen atom and can be speculated to be involved in thermal instability and metal corrosiveness. When T1/T2 in ¹⁹ F-NMR is within the above range, compound (1) tends to have higher heat resistance and lower metal corrosiveness. From the same point of view, T1/T2 is more preferably 800 or more, still more preferably 1000 or more, and even more preferably 2000 or more. Although the upper limit of T1/T2 in ¹⁹ F-NMR is not particularly limited, it may be 50,000 or less, 30,000 or less, or 10,000 or less.
The ratio T1/T2 in the fluorine-containing cyclic sulfonylimide salt is measured by ¹⁹ F-NMR, more specifically by the method described in Examples.
The purity of the fluorine-containing cyclic sulfonylimide salt is preferably 98% by mass or higher, more preferably 99% by mass or higher.

<Method for producing fluorine-containing cyclic sulfonylimide salt (compound (1))>
As described above, as a method for producing compound (1), a conventionally known method, for example, the method described in Patent Document 1 can be employed, except for the crystallization step described below. The reaction scheme of compound (1) is shown below, taking the case where R is a fluorine atom and m is 1 as an example. Such methods include the following general formula (2), as shown in the reaction scheme below:
_HO2C- ( _CR2 ) _{m- SO2F} (2)
{In the formula, each R may be the same or different and is a fluorine atom or a trifluoromethyl group, and m is 1 or 2. } (hereinafter also referred to as compound (2), including one compound in the group of compounds), through an electrolytic coupling reaction step to give compound (3) Obtained, then through a cyclization step to obtain compound (4) (hereinafter also referred to as compound (4) including one compound in the group of compounds), and finally through a cation exchange step to obtain a compound ( 1).

However, prior art methods reduce the content of impurities that are characteristic of appearing as single or multiple doublet peaks in the −115 ppm to −125 ppm region in ¹⁹ F-NMR, resulting in the desired heat resistance. It is not possible to obtain compound (1) which achieves high resistance to corrosion and low corrosion to metals, therefore it is recommended to prepare it by the method detailed below.

<Electrolytic coupling reaction step>
A bis(fluorosulfonyl) compound (compound (3)) can be produced by subjecting compound (2) to an electrolytic coupling reaction. Even if a commercially available compound (2) is used, a known method, for example, adding _SO3 to tetrafluoroethylene to obtain a sultone, obtaining a sultone ring-opening product in the presence of _NEt3 , A method of hydrolysis to obtain compound (2) as a sultone hydrolyzate may also be used.

The reaction temperature in the electrolytic coupling reaction step is not particularly limited as long as it is within a generally used range, but it is preferably -50°C to 70°C. A reaction temperature of −50° C. or higher is preferable because the electrical resistance is lowered and heat generation can be suppressed, thereby facilitating temperature control. When the reaction temperature is 70° C. or lower, decomposition of compound (2) and compound (3) can be suppressed, and the yield of compound (3) tends to increase, which is preferable. From the same point of view, the reaction temperature is more preferably -40°C to 50°C, most preferably -30°C to 40°C.

A solvent may be used in the electrolytic coupling reaction step.
The solvent is not particularly limited as long as it is commonly used, but specific examples include aromatic solvents such as benzene, toluene, chlorobenzene, and 1,2-dichlorobenzene, 1,2-dimethoxy ethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyltetrahydropyran, cyclopentylmethyl ether, and anisole Ether group-containing solvents, nitrile group-containing solvents such as acetonitrile, propionitrile, butyronitrile, and benzonitrile, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, and hydroxyl group-containing solvents such as 2-butanol , dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, and propylene carbonate. Among them, since the yield of compound (3) tends to increase, nitrile solvents such as acetonitrile, propionitrile, butyronitrile, and benzonitrile, water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol , and 2-butanol, and carbonate group-containing solvents such as dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate and propylene carbonate.
These solvents may be used alone or in combination, and since the yield of compound (3) tends to increase, a mixed solvent of water and a nitrile solvent, or water and a carbonate ester A mixed solvent of a group-containing solvent is preferred, a mixed solvent of water and a nitrile solvent is more preferred, and a mixed solvent of water and acetonitrile is most preferred. The amount of acetonitrile in the solvent is preferably 0.5-90% by weight.

The ratio (β/α) between the mass (α) of the compound (2) and the mass (β) of the solvent is not particularly limited as long as it is within the range generally used, but it should be 0.01 to 100. is preferred. When β/α is within the above range, the yield of compound (3) tends to increase. From the same point of view, β/α is more preferably 0.05-50, more preferably 0.1-10.

In the electrolytic coupling reaction step, after the electrolytic coupling reaction of compound (2), compound (2), compound (3), and a method for separating each from the reaction product containing the solvent are generally used. Any separation and removal method can be used without particular limitation. Examples include separation and removal of volatile components by distillation, separation and removal of liquid components by liquid separation, and separation and removal of insoluble solids by filtration.
These methods may be used alone or in combination of multiple methods.

The electrode used in the electrolytic coupling reaction step is not particularly limited as long as it is a generally used electrode, but from the viewpoint of suppressing the decomposition of the solvent, it is preferably a platinum electrode.

The reaction time of the electrolytic coupling reaction step is not particularly limited as long as it is within the range normally used, but is preferably 0.5 to 100 hours, more preferably 1 to 50 hours.
The pressure in the electrolytic coupling reaction step depends on the reaction temperature, but is not particularly limited as long as it is within the range normally used, but is preferably 10 kPa to 5000 kPa.
The reaction atmosphere is not particularly limited as long as it is an atmosphere that is normally used, but an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like is usually used. Among these, a nitrogen atmosphere and an argon atmosphere are preferable because they tend to produce the compound (3) more safely. A nitrogen atmosphere is more preferable because it tends to be a more economical manufacturing method.
A single reaction atmosphere may be used, or a plurality of types of reaction atmospheres may be used in combination.

<Cyclization step>
A fluorine-containing cyclic sulfonylimide ammonium salt (compound (4)) can be produced by reacting the compound (3) with ammonia.

The molar ratio (δ/γ) between the substance amount (γ) of the compound (3) and the substance amount (δ) of ammonia is not particularly limited as long as it is within a generally used range, but it should be 2 to 50. is preferred. When δ/γ is 2 or more, the yield of compound (4) tends to increase, which is preferable. When δ/γ is 50 or less, waste can be reduced, and the production method tends to be more economical, which is preferable. From the same point of view, δ/γ is more preferably 5-40, most preferably 10-30.

A solvent may be used in the cyclization step.
The solvent is not particularly limited as long as it is inert during the reaction and is generally used. Specific examples include aromatic solvents such as benzene, toluene, chlorobenzene, and 1,2-dichlorobenzene. Solvent, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyltetrahydropyran, cyclopentyl ether group-containing solvents such as methyl ether and anisole; nitrile group-containing solvents such as acetonitrile, propionitrile and benzonitrile; Examples include hydroxyl group-containing solvents. Among them, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 2-methyl Ether group-containing solvents such as tetrahydrofuran, 1,4-dioxane, 4-methyltetrahydropyran, cyclopentylmethyl ether, and anisole are more preferred. From the same viewpoint, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane and 4-methyltetrahydropyran are more preferred, and 1,2-dimethoxyethane, tetrahydrofuran and 4-methyltetrahydropyran are even more preferred.
These organic solvents may be used alone, or may be used in combination of multiple kinds of solvents.

The ratio (ζ/ε) between the mass (ε) of the compound (3) and the mass (ζ) of the solvent is not particularly limited as long as it is within the range generally used, but is preferably 0.01 to 100. preferable. When ζ/ε is within the above range, the yield of compound (4) tends to be higher. From the same point of view, ζ/ε is more preferably 0.05-50, more preferably 0.1-10.

The reaction temperature in the cyclization step is not particularly limited as long as it is within a generally used range, but it is preferably -90°C to 20°C. A reaction temperature of −90° C. or higher is preferable because the reactivity of compound (3) is enhanced and the yield of compound (4) tends to be higher. A reaction temperature of 20° C. or lower is preferable because by-products can be suppressed and the yield of compound (4) tends to increase. From the same point of view, the reaction temperature is more preferably -80°C to 10°C, most preferably -80°C to 0°C.

The reaction time in the cyclization step is not particularly limited as long as it is within the range normally used, but is preferably 1 to 100 hours, more preferably 5 to 50 hours.
The pressure in the cyclization step depends on the temperature at which the reaction is carried out, but is not particularly limited as long as it is within the range normally used, but is preferably 10 kPa to 5000 kPa.
The reaction atmosphere is not particularly limited as long as it is an atmosphere that is normally used, but an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like is usually used. Among these, a nitrogen atmosphere and an argon atmosphere are preferable because they tend to produce the compound (4) more safely. A nitrogen atmosphere is more preferable because it tends to be a more economical manufacturing method.
A single reaction atmosphere may be used, or a plurality of types of reaction atmospheres may be used in combination.

In the cyclization step, after the reaction between compound (3) and ammonia, as a method for separating each from the reaction product containing compound (4) and a solvent, a generally used separation removal method can be used. It can be used without any particular limitation. Examples include separation and removal of volatile components by distillation, separation and removal of liquid components by liquid separation, and separation and removal of unnecessary solids by filtration.
These methods may be used alone or in combination of multiple methods.

<Cation exchange step>
Compound (4) and the following general formula (5):
_MpX (5)
{wherein M is Li, Na or K, X is OH or _CO3 , and p is 1 if X is OH and 2 if X is _CO3 . } (hereinafter also referred to as compound (5) including one compound in the compound group), compound (1) can be produced.

The molar ratio (θ/η) between the substance amount (η) of the compound (4) and the substance amount (θ) of the compound (5) is not particularly limited as long as it is within a generally used range, but is 0.2. ~10 is preferred. When θ/η is 0.2 or more, the yield of compound (1) tends to increase, which is preferable. When θ/η is 10 or less, waste can be reduced, and the manufacturing method tends to be more economical, which is preferable. From the same point of view, θ/η is more preferably 0.5-5, most preferably 0.8-3.

A solvent may be used in the cation exchange step.
The solvent is not particularly limited as long as it is inert during the reaction and is generally used. Specific examples include aromatic solvents such as benzene, toluene, chlorobenzene, and 1,2-dichlorobenzene. Solvent, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran, 1,4-dioxane, 4-methyltetrahydropyran, cyclopentyl ether group-containing solvents such as methyl ether and anisole; nitrile group-containing solvents such as acetonitrile, propionitrile and benzonitrile; Examples include hydroxyl group-containing solvents. Among them, 1,2-dimethoxyethane, 1,2-diethoxyethane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 2-methyl Ether group-containing solvents such as tetrahydrofuran, 1,4-dioxane, 4-methyltetrahydropyran, cyclopentylmethyl ether, and anisole are more preferred. From the same viewpoint, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane and 4-methyltetrahydropyran are more preferred, and 1,2-dimethoxyethane, tetrahydrofuran and 4-methyltetrahydropyran are even more preferred.
These organic solvents may be used alone, or may be used in combination of multiple kinds of solvents.

The ratio (κ/ι) between the mass (ι) of the compound (4) and the mass (κ) of the solvent is not particularly limited as long as it is within a generally used range, but is preferably 0.01 to 100. preferable. When κ/ι is within the above range, the yield of compound (1) tends to be higher. From the same point of view, it is more preferably 0.05 to 50, even more preferably 0.1 to 10.

The reaction temperature in the cation exchange step is not particularly limited as long as it is within the range generally used, but it is preferably 0°C to 150°C. A reaction temperature of 0° C. or higher is preferable because the reactivity of compound (4) is enhanced and the yield of compound (1) tends to be higher. A reaction temperature of 150° C. or lower is preferable because by-products can be suppressed and the yield of compound (1) tends to increase. From the same point of view, the reaction temperature is more preferably 20°C to 140°C, most preferably 40°C to 130°C.

The reaction time of the cation exchange step is not particularly limited as long as it is within the range normally used, but is preferably 1 to 100 hours, more preferably 5 to 50 hours.
The pressure in the cation exchange step depends on the temperature at which the reaction is carried out, but is not particularly limited as long as it is within the range normally used, but is preferably 10 kPa to 5000 kPa.
The reaction atmosphere is not particularly limited as long as it is an atmosphere that is normally used, but an air atmosphere, a nitrogen atmosphere, an argon atmosphere, or the like is usually used. Among these, a nitrogen atmosphere and an argon atmosphere are preferable because they tend to allow compound (1) to be produced more safely. A nitrogen atmosphere is more preferable because it tends to be a more economical manufacturing method.
A single reaction atmosphere may be used, or a plurality of types of reaction atmospheres may be used in combination.

From the viewpoint of improving the heat resistance of compound (1), it is characteristic that it appears as a single or multiple doublet peaks in the region of -115 ppm to -125 ppm in ¹⁹ F-NMR by performing a purification operation after the cation exchange step. It is preferable to reduce the content of such impurities. The purification method is not particularly limited as long as it is a commonly used purification method, and specific examples include activated carbon treatment, heat drying, crystallization, sublimation, electrodialysis, extraction and the like. Among them, the activated carbon treatment or crystallization is preferred because it is a purification method capable of further reducing the content of such fluorine-containing impurities, and from the same point of view, crystallization is most preferred.

<Crystallization step>
In view of the high hygroscopicity of compound (1), the crystallization step is desirably carried out in a dry atmosphere because the obtained crystals are easy to handle. Although the drying atmosphere is not particularly limited, the drying can be carried out in an atmosphere of a gas such as dry air, dry nitrogen or dry argon, in an air stream, or in a vacuum and reduced pressure. Such an atmosphere may be used alone, or a combination of multiple types of atmospheres may be used.
Hereinafter, the term "poor solvent" refers to a solvent suitable for forming crystals when a solution of compound (1) is cooled, and does not necessarily mean that the solubility of compound (1) is extremely low. does not mean
The solvent used for crystallization in the present invention is preferably a monodentate chain ether solvent from the viewpoint of satisfying both relatively high solubility of compound (1) and low coordination with metals. desirable. Such monodentate coordinating acyclic ether solvents generally tend to have lower metal coordinating properties, dielectric constants, and dipole moments than other polar solvents and cyclic ethers. It is believed that it works favorably in the removal of the solvent from the crystal, and therefore when such a solvent is used in the crystallization process, the amount of residual solvent tends to be reduced.
In the crystallization step, it is desirable to use a single solvent from the viewpoint of production costs. Since the monodentate chain ether solvent itself functions effectively as a poor solvent in crystallization, it is sufficiently possible to obtain a highly pure fluorine-containing cyclic sulfonylimide salt using only a single solvent. However, a plurality of solvents can be mixed, and crystallization can be promoted by adding a polar solvent as a good solvent or further adding a poor solvent. Mixing a plurality of solvents tends to increase the amount of solvent remaining after drying, which may be disadvantageous in terms of heat history and production costs. Also, when a polar solvent, which is a good solvent, is added, the resulting crystals may adhere to the inside of the crystallizer.
A "monodentate coordinating" solvent means a solvent that has one site with coordinating ability to a metal. An ether bond is mentioned as a site|part which has coordinating property.

From the viewpoint of reducing the amount of residual solvent after drying, the monodentate chain ether solvent preferably has a low boiling point, that is, has a carbon number of 6 or less. , isopropyl methyl ether, isopropyl ethyl ether, isopropyl ether, butyl methyl ether, butyl ethyl ether, isobutyl methyl ether, isobutyl ethyl ether, sec-butyl methyl ether, sec-butyl ethyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, pentyl methyl ether, isopentyl methyl ether, sec-pentyl methyl ether, tert-pentyl methyl ether, neopentyl methyl ether, cyclopentyl methyl ether and the like. From the viewpoint of solubility of compound (1), propyl methyl ether, propyl ethyl ether, isopropyl methyl ether, isopropyl ethyl ether, butyl methyl ether, butyl ethyl ether, isobutyl methyl ether, isobutyl ethyl ether, sec-butyl methyl ether, sec- Butyl ethyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, pentyl methyl ether, isopentyl methyl ether, sec-pentyl methyl ether, tert-pentyl methyl ether, neopentyl methyl ether, cyclopentyl methyl ether are more preferred, and further Preferred are butyl methyl ether, butyl ethyl ether, tert-butyl methyl ether, tert-butyl ethyl ether, tert-pentyl methyl ether and cyclopentyl methyl ether. A single monodentate coordinating chain ether solvent may be used alone, or a plurality of types of monodentate coordinating chain ether solvents may be used in combination.
When a polar solvent is added as a good solvent, the good solvent to be used is not particularly limited, but acetone, tetrahydrofuran, dimethyl carbonate, and diethyl carbonate are preferred because they particularly preferably dissolve compound (1) and have a relatively low boiling point. , ethylene carbonate, propylene carbonate, acetonitrile, methyl acetate, ethyl acetate, butyl acetate and the like. A single good solvent may be used, or a plurality of kinds of good solvents may be used in combination.
When a poor solvent is specifically added to promote crystallization, the poor solvent to be used is not particularly limited. It is preferably at the boiling point, and includes pentane, hexane, cyclohexane, heptane, chloroform, dichloromethane, 1,2-dichloroethane and the like. A poor solvent may be used alone, or a plurality of types of poor solvents may be used in combination.

The crystallization step mainly consists of a step of dissolving compound (1) in a monodentate chain ether solvent and a crystallization step. You can do it. This removal step can be carried out by any of known methods such as centrifugation, natural filtration, vacuum filtration, and pressure filtration. When performing filtration, any known filter medium may be used as long as it can withstand the use of an organic solvent, and a filter aid may be added. The pore size of the filtering material is preferably 10 μm or less, more preferably 1 μm or less.

In the step of dissolving compound (1), 100 to 1000% by mass, more preferably 100 to 500% by mass, and still more preferably 100 to 300% by mass of monodentate coordination with respect to the compound (1)-containing solid before crystallization. Add a linear linear ether solvent. In this step, stirring with a magnetic stirrer or stirring blades, or acceleration of dissolution by shaking, ultrasonic vibration, or the like may be performed. The temperature during dissolution is not particularly limited, but the dissolution can be carried out at a temperature from 0°C to the boiling point of the solvent plus 50°C. When heating above the boiling point of the solvent, a known reflux apparatus can be used.

The crystallization step can be carried out, for example, by cooling the solution of compound (1) obtained in the dissolution step to a desired temperature. When cooling, it is preferable to cool gently to a desired temperature from the viewpoint of purifying the resulting crystals. The cooling temperature is preferably -100°C to 30°C, more preferably -80°C to 20°C, still more preferably -50°C to 20°C. During crystallization, seed crystals may be added as widely practiced as a known technique. In addition, concentration may be performed by distilling off the solvent before and during cooling, and crystallization can be promoted by adding the poor solvent while cooling.

The crystallized compound (1) can be collected by any known method such as centrifugation, gravity filtration, vacuum filtration, pressure filtration, or the like. Any known filtering material may be used for filtration as long as it can withstand the use of organic solvents. The pore size of the filtering material is preferably 10 μm or less, more preferably 1 μm or less. For high purity, it is preferable to wash the crystals with a monodentate chain ether solvent, a poor solvent, or a separately prepared solvent solution of compound (1) when collecting the crystals. The liquid used for washing may be separately heated or cooled to a desired temperature before use.

Although it is disadvantageous in terms of production cost, the above crystallization step can be repeated multiple times as necessary in order to obtain crystals of higher purity.

From the viewpoint of improving the efficiency of the production process, it is desirable to recover all the liquid portion and washing liquid removed during the collection of the crystals and reuse them in the dissolution process or the crystallization process.

<Drying process>
Next, it is preferable to carry out a drying step in order to remove excess solvent in the fluorine-containing cyclic sulfonylimide salt after collection. In the drying step, heat-reduced-pressure drying can be performed as commonly known. The heating temperature is preferably 40°C, more preferably 60°C. Considering stability, the upper limit is preferably 200°C. The pressure during decompression is preferably 100 hPa or less, more preferably 50 hPa or less, still more preferably 10 hPa or less, and most preferably 1 hPa or less. During drying, crushing of crystals and stirring may be added for the purpose of speeding up the drying. In this case, further reductions in heat history, time and cost can be expected. According to the above crystallization method, the crystals obtained have a small amount of residual solvent, and the adhesion of crystals to each other and to the container can be suppressed. Widely used stirrer blades and mills can be used.

Examples that specifically describe the present embodiment will be exemplified below. The present invention is not limited to the following examples as long as the gist thereof is not exceeded.

<Analysis method>
Analysis methods and the like used in Examples and Comparative Examples were as follows.

(Nuclear Magnetic Resonance Analysis (NMR): Molecular Structural Analysis by ¹⁹ F-NMR)
The products obtained in Examples and Comparative Examples were subjected to molecular structure analysis using ¹⁹ F-NMR (376 MHz) under the following measurement conditions.
[Measurement condition]
Measuring device: JNM-ECZ400S type nuclear magnetic resonance device (manufactured by JEOL Ltd.)
Observation nucleus: ^19F
Solvent: deuterated chloroform, deuterated dimethylsulfoxide Reference material: trichlorofluoromethane ( ¹⁹ F, 0.00 ppm)
Pulse width: 6.5 μs Waiting time: 2 seconds Accumulation times: 1024 times

(thermal mass measurement)
For the products obtained in Examples and Comparative Examples, the mass reduction rate was measured under the following measurement conditions.
Aluminum pan (“Crimp cell (for autosampler) part number 346-66963-91”, manufactured by Shimadzu Corporation, a cover was not used at the time of measurement) was weighed 5 mg of the sample, and simultaneous differential thermal thermogravimetric measurement was performed. Using an apparatus ("DTG-60A", manufactured by Shimadzu Corporation), under a nitrogen stream (flow rate 50 mL/min), the temperature was raised from 25 ° C. to 100 ° C. at a temperature increase rate of 10 ° C./min, and 30 at 100 ° C. After holding for 1 minute, the sample was heated at a measurement temperature range of 100° C. to 500° C. at a heating rate of 10° C./minute, and the state of mass reduction was observed.
The process of heating at a measurement temperature range of 100 ° C. to 500 ° C. and a heating rate of 10 ° C./min, with the mass at the start of heating from 100 ° C. after holding at 100 ° C. for 30 minutes as a reference (100 mass%). The temperature (° C.) at which a mass reduction rate of 1% by mass and 2% by mass was confirmed was observed.

(ICP emission spectroscopy)
Quantitative measurement was performed under the following measurement conditions for the solutions obtained in the examples after the metal immersion test.
[Measurement condition]
Measuring device: SPS3520UV-DD (manufactured by Hitachi High-Tech Science Co., Ltd.)
Measurement atoms: Co, Ni, Mn
Sample preparation conditions: 2 g of an aqueous solution of compound (1) was mixed with 28 g of a 1% by mass nitric acid aqueous solution to prepare a measurement sample.
RF power: 1.2kW
Plasma gas (argon) flow rate: 16 L/min Auxiliary gas (argon) flow rate: 0.5 L/min Carrier gas (argon) pressure: 0.24 MPa
Carrier gas (argon) flow rate: 0.3 L/min Photometric height: 12 mm

<Raw materials used>
Raw materials used in Examples and Comparative Examples are shown below.
(Fluorosulfonyl Group-Containing Carboxylic Acid Compound (2))
・ 2,2-difluoro-2-(fluorosulfonyl)acetic acid (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)

・Ammonia (manufactured by Sumitomo Seika Co., Ltd.)

(alkali metal salt (5))
・Lithium hydroxide monohydrate (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)

(solvent)
Acetonitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., dried molecular sieve 3A 1/16 (manufactured by Fujifilm Wako Purechemical Co., Ltd.) is added, dehydrated, and the water content is reduced by removing the molecular sieve 3A 1/16. It was adjusted)
- Tetrahydrofuran (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., dried molecular sieve 3A 1/16 (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) is added, dehydrated, and the water content is determined by removing the molecular sieve 3A 1/16. It was adjusted)

・Activated carbon (manufactured by FUJIFILM Wako Pure Chemical Industries, Ltd.)

<Reaction temperature>
The reaction temperature was room temperature when it was room temperature without external heating and cooling. When using an external heating/cooling device such as a water bath or an oil bath, the reaction temperature was the temperature of the medium used in the external heating/cooling device.

[Example 1]
<Electrolytic coupling reaction step>
After adding a stirrer, acetonitrile (59 g) and water (75 g) to a 200 mL three-necked flask under a nitrogen atmosphere, it was cooled to 0° C. and FO ₂ SCF ₂ CO ₂ H (compound (2), 25.7 g, 144 .3 mmol) was added. As an anode and a cathode, platinum plate electrodes (25 mm×50 mm) were placed at intervals of 6 mm and immersed in the solution. A current of 1.5 A was applied to the electrodes for 4 hours while stirring was maintained under cooling at 0°C. When the stirring was stopped after the completion of the electrification, the reaction solution was separated into two phases. When the lower layer was fractionated, 7.9 g of liquid was obtained. A sample of the obtained liquid was measured by ¹⁹ F-NMR, and it was found to contain 90.3% by mass (37.1% yield) of FO ₂ SCF ₂ CF ₂ SO ₂ F (compound (3)). was confirmed.
The crude FO ₂ SCF ₂ CF ₂ SO ₂ F (compound (3)) obtained by the above operation is purified by simple atmospheric distillation to obtain 95.6% by mass of FO ₂ SCF ₂ CF ₂ SO ₂ F ( 6.9 g of liquid containing compound (3)) was obtained.
_{FO2SCF2CF2SO2F _ _ _}
¹⁹ F-NMR: δ (ppm) 46.1 (2F), -108.7 (4F)

¹⁹Ｆ－ＮＭＲ：δ（ｐｐｍ）－１１５．４（４Ｆ）
で表される含フッ素環状スルホニルイミドアンモニウム塩（化合物（４））が９６．２質量％（収率９８．３％）含まれていることが確認された。
＜カチオン交換工程＞
１Ｌの三口フラスコに、窒素雰囲気下、攪拌子、テトラヒドロフラン（４００ｇ）、実施例２で得られた含フッ素環状スルホニルイミドのアンモニウム塩（１８７．０ｇ、純度９６．２質量％、６９１．４ｍｍоｌ）、及び水酸化リチウム一水和物（３２．２ｇ、７６７．４ｍｍоｌ）を添加し、７０℃で４時間攪拌した。得られた反応液を減圧濃縮した後、水（５００ｍＬ）、活性炭（６５．８ｇ）を添加し、１０５℃で３時間攪拌した。得られた反応液を加圧濾過し不溶固体を除去した後、減圧濃縮し肌色固体を得た。得られた肌色固体にテトラヒドロフラン（８８９ｇ）を添加し、５０℃で３０分攪拌した後加圧濾過により不溶固体を除去し、減圧濃縮することで１７０．３ｇの白色固体を得た。得られた固体をサンプリングし、ＩＣＰ発光分光分析法により分析を行ったところ、アンモニウムカチオンがリチウムカチオンに交換されていることを確認した。さらに、¹⁹Ｆ－ＮＭＲで分析すると、以下の構造式：

¹⁹Ｆ－ＮＭＲ：δ（ｐｐｍ）－１１５．４（４Ｆ）
で表される含フッ素環状スルホンイミドのリチウム塩（化合物（１））が９９．１質量％（収率９８．０％）含まれていることが確認された。 <Cyclization step>
A 3 L autoclave was cooled to −78° C., ammonia gas (250 g, 14680 mmol), and tetrahydrofuran (222.3 g) were added, then the FO ₂ SCF ₂ CF ₂ SO ₂ F obtained in Example 1 (208 g, purity A solution of 90.5 mass %, 707.3 mmol) in tetrahydrofuran (222.3 g) was added dropwise over 3 hours. After completion of dropping, the mixture was stirred at room temperature for 12 hours. After stirring was completed, the reaction solution was filtered under pressure to remove insoluble solids, and the filtrate was concentrated under reduced pressure and dried to obtain 188.0 g of flesh-colored solids. The resulting solid was sampled and analyzed by ¹⁹ F-NMR, which revealed the following structural formula:

¹⁹ F-NMR: δ (ppm) -115.4 (4F)
It was confirmed that 96.2% by mass (yield 98.3%) of the fluorine-containing cyclic sulfonylimide ammonium salt represented by (Compound (4)) was contained.
<Cation exchange step>
A 1 L three-necked flask was charged under a nitrogen atmosphere with a stirrer, tetrahydrofuran (400 g), the fluorine-containing cyclic sulfonylimide ammonium salt obtained in Example 2 (187.0 g, purity 96.2% by mass, 691.4 mmol), and lithium hydroxide monohydrate (32.2 g, 767.4 mmol) were added and stirred at 70° C. for 4 hours. After concentrating the obtained reaction solution under reduced pressure, water (500 mL) and activated carbon (65.8 g) were added, and the mixture was stirred at 105° C. for 3 hours. The resulting reaction solution was filtered under pressure to remove insoluble solids, and then concentrated under reduced pressure to obtain a skin-colored solid. Tetrahydrofuran (889 g) was added to the obtained flesh-colored solid, and the mixture was stirred at 50°C for 30 minutes, and the insoluble solid was removed by pressure filtration, followed by concentration under reduced pressure to obtain 170.3 g of white solid. The resulting solid was sampled and analyzed by ICP emission spectrometry, confirming that the ammonium cations were exchanged with lithium cations. Furthermore, analysis by ¹⁹ F-NMR revealed the following structural formula:

¹⁹ F-NMR: δ (ppm) -115.4 (4F)
It was confirmed that 99.1% by mass (yield 98.0%) of the lithium salt of fluorine-containing cyclic sulfonimide represented by (compound (1)) was contained.

<Crystallization step>
10 g of the synthesized compound (1) and 27 g of tert-butyl methyl ether were weighed into a 100 mL eggplant flask equipped with a stirrer, and the mixture was stoppered and stirred for 30 minutes. After filtering the resulting mixture under reduced pressure, it was cooled in a freezer at -20°C for 30 minutes to yield colorless crystals. After removing the liquid portion by decantation, tert-butyl methyl ether at −35° C. was added and mixed with a spatula to wash the crystals, and the liquid portion was removed by decantation. The obtained crystals were dried under reduced pressure at 60° C. and 40 hPa for 3 hours without stirring. After drying, 4.9 g of crystals were obtained. A sample of the obtained crystal was analyzed by ¹⁹ F-NMR, and it was confirmed that it contained 99.2% by mass of compound (1) (yield 49.0%). In ¹⁹ F-NMR, the ratio T1/T2 of the sum T1 of the integrated values of the compound (1) peaks and the sum T2 of the integrated values of the impurity peaks seen as a single doublet at −117.2 ppm was 3170.

[Example 2]
The electrolytic coupling reaction step, the cyclization step, and the cation exchange step were carried out in the same manner as in Example 1 except that the following steps were used instead of the crystallization step to obtain a lithium salt of a fluorine-containing cyclic sulfonimide (compound (1 )) was manufactured.
In a 6 mL vial, 0.2 g of synthesized compound (1) and 0.35 g of cyclopentyl methyl ether were weighed to obtain a dispersion. After filtering the resulting dispersion, it was dried under reduced pressure under conditions of 100° C. and 10 hPa for 10 hours to obtain 0.09 g of compound (1). T1/T2 was 581 in ¹⁹ F-NMR.

[Comparative Example 1]
An electrolytic coupling reaction step, a cyclization step, and a cation exchange step were carried out in the same manner as in Example 1, except that the crystallization step was not carried out, to produce a lithium salt of fluorine-containing cyclic sulfonimide (compound (1)). In ¹⁹ F-NMR, T1/T2 was 215, and a large amount of fluorine-containing impurities were contained.

The heat resistance of the fluorine-containing cyclic sulfonimide lithium salt (compound (1)) obtained in Example 1 and Comparative Example 1 was measured according to the following method.
[Heat resistance evaluation]
Weigh 5 mg of sample in an aluminum pan, use a simultaneous differential thermal thermogravimetry device ("DTG-60A", manufactured by Shimadzu Corporation), under dry air flow (flow rate 50 mL / min), 25 ° C. to 100 ° C. The temperature was raised at a temperature increase rate of 10°C/min to 100°C for 30 minutes, then heated at a temperature increase rate of 10°C/min in a measurement temperature range of 100°C to 500°C, and the state of mass reduction was observed. The results are shown in Table 1 below.

From Table 1, it can be seen that the fluorine-containing cyclic sulfonimide lithium salt (compound (1)) of Example 1, which has a large T1/T2 and a reduced content of fluorine-containing impurities, is a comparative example having a large content of fluorine-containing impurities. It can be seen that the heat resistance is improved as compared with the lithium salt of fluorine-containing cyclic sulfonimide of No. 1 (compound (1)). This is probably because the content of fluorine-containing impurities was reduced, and as a result of suppressing the decomposition of compound (1) caused by fluorine-containing impurities, the heat resistance of compound (1) was improved.

The metal corrosivity of the fluorine-containing cyclic sulfonimide lithium salt (compound (1)) obtained in Example 1 and Comparative Example 1 was measured according to the following method.

<Electrode plate immersion test>
A solution was prepared by dissolving 20 g of the compound (1) obtained in Example 1 and Comparative Example 1 in 30 g of ultrapure water, and a circular electrode plate of LiNi0.8Co0.1Mn0.1O2 (16 mm diameter, 0.1 mm thickness) was prepared. A composite of 2 mm, mass 0.043 g, coated with a mixture of PVDF and carbon black on an aluminum foil, and press-fired) was immersed. This was allowed to stand at room temperature for two weeks under an air atmosphere. After filtering the immersed solution, the amount of eluted metal was quantified by ICP emission spectrometry. The results are shown in Table 2 below.

表２中、Ｎｉ、Ｃｏ及びＭｎの溶出量は、浸漬処理後の溶液中の質量割合を示す。また、Ｎ．Ｄ．は定量限界未満の値であったことを示す。

In Table 2, the elution amounts of Ni, Co and Mn indicate mass ratios in the solution after the immersion treatment. Also, N. D. indicates that the value was less than the limit of quantification.

The lithium salt of the fluorine-containing cyclic sulfonimide (compound (1)) of the example in which T1/T2 was large and the content of fluorine-containing impurities was reduced had metal corrosiveness as compared with Comparative Example 1 having a large content. It turns out that it is reduced to 1/2 or less.

The fluorine-containing cyclic sulfonylimide salt according to the present invention has high heat resistance, can be used in a wide temperature range, and has low metal corrosiveness. It can be suitably used as

Claims (6)

The following general formula (1):

{wherein each R may be the same or different and is a fluorine atom or a trifluoromethyl group, n is an integer of 1 to 4, and M is Li, Na or K is. }, wherein the sum T1 of the integrated values of the peaks of the compound represented by the general formula (1) in ¹⁹ F-NMR and the unit in the region of -115 ppm to -125 ppm A fluorine-containing cyclic sulfonylimide salt, characterized in that the ratio T1/T2 to the sum T2 of integrated values of impurity peaks characterized by appearing as one or more doublet peaks is 500 or more. . The fluorine-containing cyclic sulfonylimide salt according to claim 1, wherein n is an integer of 1 to 3 in the general formula (1). 3. The fluorine-containing cyclic sulfonylimide salt according to claim 2, wherein n is 2 in the general formula (1). The fluorine-containing cyclic sulfonylimide salt according to any one of claims 1 to 3, wherein R is a fluorine atom in the general formula (1). The fluorine-containing cyclic sulfonylimide salt according to any one of claims 1 to 4, wherein M is Li in the general formula (1). The following structural formula:

The fluorine-containing cyclic sulfonylimide salt according to any one of claims 1 to 5, represented by