JP4973805B2 - Fluorine-containing sulfolane and method for producing fluorine-containing sulfolane - Google Patents

Description

The present invention relates to fluorine-containing sulfolane and a method for producing fluorine-containing sulfolane.

Sulfolane compounds are used in various applications because of their excellent high temperature characteristics and high dielectric constant characteristics. Among them, demand for energy storage devices such as lithium-ion batteries has increased rapidly due to the recent popularization of electric vehicles and hybrid vehicles, and the rapid spread of digital portable electronic devices such as mobile phones, personal digital assistants, and notebook computers. The use of the electrolyte solution used for energy storage devices as a solvent or additive is particularly expected.

With the rapid increase in demand for such energy storage devices, there is an increasing demand for higher performance such as higher energy density and higher power density in energy storage devices. Even higher performance is required.

As a sulfolane compound known so far, for example, in Patent Document 1, sulfolane is produced by reacting sulfolane with fluorine gas. Non-Patent Document 1 describes a reaction of adding fluorine gas to sulfolene.

In Patent Document 2, a fluorinated sulfolane compound is produced by a reaction between sulfolanes and fluorine gas.

JP 2002-47286 A JP 2003-132944 A

J. et al. Florine. Chem. , 93, 1, 27, 1999

The sulfolane compounds have various excellent properties as described above, and various sulfolane compounds have been produced. However, the sulfolane compounds are not particularly satisfactory in terms of oxidation resistance, and correspond to higher performance of energy storage devices. Therefore, a material with better oxidation resistance has been desired.

The present invention provides a novel fluorine-containing sulfolane that can be suitably used as an electrolyte for an energy storage device and a method for producing the same.

As a result of intensive studies by the present inventors, a novel fluorine-containing sulfolane having a specific structure, for which a conventional synthesis method has not been known, has been successfully synthesized.

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表されることを特徴とする含フッ素スルホランに関する。
なお、特許文献１及び非特許文献１には、フルオロアルキル基を有するスルホランは開示されていない。また、特許文献２には、フッ化スルホラン化合物が開示されているが、特許文献２に記載のフッ化スルホラン化合物の製造方法は、スルホラン類とフッ素ガスとを反応させて、スルホラン環を構成する炭素原子に結合した水素原子をフッ素原子に置き換えるものであり、本発明の含フッ素スルホランを製造することはできないものである。 The present invention provides the following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
It is related with the fluorine-containing sulfolane characterized by these.
Patent Document 1 and Non-Patent Document 1 do not disclose sulfolane having a fluoroalkyl group. Patent Document 2 discloses a fluorinated sulfolane compound. However, in the method for producing a fluorinated sulfolane compound described in Patent Document 2, a sulfolane ring and a fluorine gas are reacted to form a sulfolane ring. The hydrogen atom bonded to the carbon atom is replaced with a fluorine atom, and the fluorine-containing sulfolane of the present invention cannot be produced.

（式中、Ｘ^１〜Ｘ^４は、それぞれ独立して、トリフルオロメチル基、トリフルオロメトキシ基、水素原子、又は、ハロゲン原子である。ただし、Ｘ^１〜Ｘ^４のうち少なくとも１つは、フッ素原子、トリフルオロメチル基、又は、トリフルオロメトキシ基である。）
で表されるフルオロアルキル基であることが好ましい。 Rf is the following formula (2):

(Wherein, X ^{1 to} X ⁴ are each independently a trifluoromethyl group, a trifluoromethoxy group, a hydrogen atom, or a halogen atom. However, at least one of X ^{1 to} X ⁴ is A fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.)
It is preferable that it is the fluoroalkyl group represented by these.

Rf _{is, -CF 2 CFHOCF 3, -CH 2} CFHCF 3, -CH 2 CH 2 CF 3, -CFHCF 2 H, -CFHCFHCF 3, -CF 2 CF 2 H, -CH 2 CF 2 H, and, -CF It is preferably at least one group selected from the group consisting of ₂ CFHCF ₃ .

The present invention relates to an electrolytic solution containing the fluorine-containing sulfolane of the present invention.

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表される化合物を酸化剤と反応させて、下記式（１）：

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表される含フッ素スルホランを得る工程、を含むことを特徴とする含フッ素スルホランの製造方法に関する。 The present invention provides the following formula (3):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by the following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
A process for obtaining a fluorinated sulfolane represented by the formula:

The oxidizing agent is preferably at least one compound selected from the group consisting of peroxides, perhalogen oxides, permanganates, and chromates.

（式中、Ｒｆ^１は、ヘテロ原子を含んでいてもよい炭素数２〜８のフルオロアルキル基である。）
で表される化合物であり、
前記式（１）で表される含フッ素スルホランが、下記式（５）：

（式中、Ｒｆ^１は、ヘテロ原子を含んでいてもよい炭素数２〜８のフルオロアルキル基である。）
で表される化合物であることが好ましい。 The compound represented by the formula (3) is obtained by reacting tetrahydrothiophene with a fluoroalkene having 2 to 8 carbon atoms:

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by
The fluorine-containing sulfolane represented by the formula (1) is represented by the following formula (5):

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
It is preferable that it is a compound represented by these.

（式中、Ｘ^１〜Ｘ^４は、それぞれ独立して、トリフルオロメチル基、トリフルオロメトキシ基、水素原子、又は、ハロゲン原子である。ただし、Ｘ^１〜Ｘ^４のうち少なくとも１つは、フッ素原子、トリフルオロメチル基、又は、トリフルオロメトキシ基である。）
で表される化合物であることが好ましい。 The fluoroalkene has the following formula (6):

(Wherein, X ^{1 to} X ⁴ are each independently a trifluoromethyl group, a trifluoromethoxy group, a hydrogen atom, or a halogen atom. However, at least one of X ^{1 to} X ⁴ is A fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.)
It is preferable that it is a compound represented by these.

The fluoroalkene _{is, CH 2 = CFCF 3, CH} 2 = CH-CF 3, CF 2 = CF-OCF 3, CFH = CFCF 3, CFH = CF 2, CH 2 = CF 2, CF 2 = CF 2 And at least one compound selected from the group consisting of CF ₂ ═CFCF ₃ is preferred.

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基であり、Ｘ^６は、フッ素原子、塩素原子、臭素原子、又は、ヨウ素原子であり、Ｘ^５は、塩素原子、臭素原子、又は、ヨウ素原子である。）で表される化合物を得る工程、
２）前記式（７）で表される化合物を、チオール化剤と反応させて、下記式（８）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基であり、Ｘ^５は、塩素原子、臭素原子、又は、ヨウ素原子である。）で表される化合物を得る工程、
３）前記式（８）で表される化合物を環化反応させる工程
を含む製造方法により得られる下記式（９）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基である。）
で表される化合物であり、
前記式（１）で表される含フッ素スルホランが、下記式（１０）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基である。）
で表される化合物であることが好ましい。 The compound represented by the formula (3) is
1) 5-halogen-1-pentene (halogen: fluorine atom, chlorine atom, bromine atom, or iodine atom) is substituted with Rf ² X ⁵ (wherein Rf ² is a carbon atom that may contain a hetero atom) 1-7 fluoroalkyl groups, and X ⁵ is a chlorine atom, a bromine atom, or an iodine atom.)
Is reacted with a compound represented by the following formula (7):

(In the formula, Rf ² is a C1-C7 fluoroalkyl group that may contain a hetero atom, X ⁶ is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X ⁵ Is a chlorine atom, a bromine atom, or an iodine atom.)
2) The compound represented by the formula (7) is reacted with a thiolating agent to obtain the following formula (8):

(In the formula, Rf ² is a C1-C7 fluoroalkyl group which may contain a hetero atom, and X ⁵ is a chlorine atom, a bromine atom or an iodine atom). Obtaining a compound;
3) The following formula (9) obtained by a production method including a step of cyclizing the compound represented by the formula (8):

(In the formula, Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom.)
A compound represented by
The fluorine-containing sulfolane represented by the formula (1) is represented by the following formula (10):

(In the formula, Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom.)
It is preferable that it is a compound represented by these.

Rf ² is — (CF ₂ ) _n H (n is an integer of 1 to 7), — (CF ₂ ) _m CF ₃ (m is an integer of 1 to 6), —CF (CF _{3 2} ) and at least one group selected from the group consisting of —CH (CF ₃ ) ₂ is preferable.

The fluorine-containing sulfolane of the present invention is very useful as a solvent or additive used in an electrolyte solution of an energy storage device. Moreover, the fluorine-containing sulfolane of the present invention has excellent oxidation resistance. The method for producing a fluorine-containing sulfolane of the present invention can reliably produce the novel fluorine-containing sulfolane by a simple method.

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表されることを特徴とする含フッ素スルホランに関する。 The present invention provides the following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
It is related with the fluorine-containing sulfolane characterized by these.

Since the fluorine-containing sulfolane of the present invention is a fluorine-containing sulfolane having a specific structure having a fluoroalkyl group, it is excellent in oxidation resistance and exhibits high electrochemical stability. The fluorine-containing sulfolane represented by the above formula (1) is difficult to synthesize and cannot be synthesized conventionally. As a result of intensive studies by the present inventors, the synthesis was succeeded for the first time by using the production method described later, and the fluorine-containing sulfolane represented by the above formula (1) has excellent oxidation resistance and high electrochemical stability. Was found to show. The reason why oxidation resistance and electrochemical stability are improved is not clear, but by introducing a fluoroalkyl group into sulfolane, electrons on the oxygen atom bonded to the sulfur atom are attracted and the coordination power decreases. It is speculated that it may be caused by this.

Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom. The number of carbon atoms is preferably 2 to 8, more preferably 2 to 6, and further preferably 3 to 6. Here, the “hetero atom” represents a halogen atom other than a fluorine atom, an oxygen atom, a sulfur atom, a nitrogen atom, or the like. Further, “may contain a heteroatom” means that it contains a heteroatom or does not contain a heteroatom. That is, the “C1-C8 fluoroalkyl group optionally containing a heteroatom” means a C1-C8 fluoroalkyl group or a C1-C8 fluoroalkyl group containing a heteroatom. Represents. In the present specification, “which may contain a hetero atom” has the same meaning hereinafter.

The fluoroalkyl group may be an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and may be a perfluoroalkyl group. Further, it may be a linear fluoroalkyl group or a branched fluoroalkyl group.

Examples of Rf include fluoroalkyl groups such as a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, a fluorobutyl group, a fluoropentyl group, and a fluorohexyl group. These fluoroalkyl groups may be linear or branched. Further, it may be a perfluoroalkyl group.

（式中、Ｘ^１〜Ｘ^４は、それぞれ独立して、トリフルオロメチル基、トリフルオロメトキシ基、水素原子、又は、ハロゲン原子である。ただし、Ｘ^１〜Ｘ^４のうち少なくとも１つは、フッ素原子、トリフルオロメチル基、又は、トリフルオロメトキシ基である。）
で表されるフルオロアルキル基であることが好ましく、下記式（２−１）：

（式中、Ｘ^３、Ｘ^４は、式（２）と同様である。）
で表されるフルオロアルキル基であることがより好ましい。 More specifically, as Rf, the following formula (2):

(Wherein, X ^{1 to} X ⁴ are each independently a trifluoromethyl group, a trifluoromethoxy group, a hydrogen atom, or a halogen atom. However, at least one of X ^{1 to} X ⁴ is A fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.)
Is preferably a fluoroalkyl group represented by the following formula (2-1):

(In the formula, X ³ and X ⁴ are the same as those in the formula (2).)
It is more preferable that it is the fluoroalkyl group represented by these.

Examples of the fluoroalkyl group represented by the formula (2) include —CF ₂ CFHCF ₃ , —CF ₂ CF ₂ H, —CF ₂ CFHOCF ₃ , —CFHCF ₂ H, —CFHCHFHCF ₃ , —CH ₂ CFHCF ₃ , — _{CH 2 CH 2 CF 3, -CH} 2 CF 2 H, -CF 2 CFClH, -CF 2 CCl 2 H , and the like. Of _{these, -CF 2 CFHOCF 3, -CH 2} CFHCF 3, -CH 2 CH 2 CF 3, -CFHCF 2 H, -CFHCFHCF 3, -CF 2 CF 2 H, -CH 2 CF 2 H and,, - Preferably, at least one selected from the group consisting of CF ₂ CFHCF _3, and at least one selected from the group consisting of —CF ₂ CFHCF ₃ , —CF ₂ CF ₂ H, and —CF ₂ CFHOCF ₃ It is more preferable that

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表される化合物を酸化剤と反応させて、下記式（１）：

（式中、Ｒｆは、ヘテロ原子を含んでいてもよい炭素数１〜８のフルオロアルキル基である。）
で表される含フッ素スルホランを得る工程、を含むことを特徴とする含フッ素スルホランの製造方法に関する。
本発明の含フッ素スルホランの製造方法は、上記含フッ素スルホランを得る工程を含む限り、その他の工程を含んでいてもよい。例えば、含フッ素スルホランを製造した後に、精製工程を行うことにより、純度の高い含フッ素スルホランを得ることができる。上記精製工程は、再結晶、濾過、精留など通常有機化合物の精製のために行われる方法を採ることができる。 The present invention also provides the following formula (3):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by the following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
A process for obtaining a fluorinated sulfolane represented by the formula:
The method for producing a fluorine-containing sulfolane of the present invention may include other steps as long as it includes the step of obtaining the fluorine-containing sulfolane. For example, a highly purified fluorine-containing sulfolane can be obtained by producing a fluorine-containing sulfolane and then performing a purification step. In the purification step, a method usually used for purification of an organic compound such as recrystallization, filtration and rectification can be employed.

Examples of Rf in the above formula (3) include the same as Rf in the formula (1). As the oxidizing agent, those described later can be used. Moreover, as a method of reacting the compound represented by the formula (3) with an oxidant, a method of introducing an oxidant into the liquid phase compound represented by the formula (3) and reacting the compound can be mentioned. Details of the method will be described later.

（式中、Ｒｆ^１は、ヘテロ原子を含んでいてもよい炭素数２〜８のフルオロアルキル基である。）
で表される化合物、又は、下記式（９）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基である。）
で表される化合物が好ましい。 As a compound shown by the said Formula (3), following formula (4) obtained by making C2-C8 fluoroalkene react with tetrahydrothiophene:

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
Or a compound represented by the following formula (9):

(In the formula, Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom.)
The compound represented by these is preferable.

In the method for producing fluorine-containing sulfolane of the present invention, the production method using the compound represented by the above formula (4) is referred to as “first production method”, and the production method using the compound represented by the above formula (7) This is referred to as “second manufacturing method”.

Hereinafter, the first manufacturing method will be described.

（式中、Ｒｆ^１は、ヘテロ原子を含んでいてもよい炭素数２〜８のフルオロアルキル基である。）
で表される化合物を得る工程、及び、
上記式（４）で表される化合物を酸化剤と反応させて、下記式（５）：

（式中、Ｒｆ^１は、ヘテロ原子を含んでいてもよい炭素数２〜８のフルオロアルキル基である。）
で表される含フッ素スルホランを得る工程、を含むものである。 The first production method of the present invention comprises:
Tetrahydrothiophene is reacted with a fluoroalkene having 2 to 8 carbon atoms to obtain the following formula (4):

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
A step of obtaining a compound represented by:
The compound represented by the above formula (4) is reacted with an oxidizing agent to form the following formula (5):

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
The process of obtaining the fluorine-containing sulfolane represented by these is included.

The first production method of the present invention can produce the fluorine-containing sulfolane represented by the above formula (5) simply and reliably. In addition, fluorine-containing sulfolane having excellent oxidation resistance and high electrochemical stability can be produced.

The fluoroalkene preferably has 2 to 8 carbon atoms, more preferably 3 to 6 carbon atoms. Examples of the fluoroalkene include fluoroethylene, fluoropropylene, fluorobutylene, fluoropentene, and fluorohexene. These fluoroalkenes may be linear or branched. Further, the structure may contain a hetero atom, and in particular, the structure may have an ether bond. Perfluoroalkene may be used.

（式中、Ｘ^１〜Ｘ^４は、それぞれ独立して、トリフルオロメチル基、トリフルオロメトキシ基、水素原子、又は、ハロゲン原子である。ただし、Ｘ^１〜Ｘ^４のうち少なくとも１つは、フッ素原子、トリフルオロメチル基、又は、トリフルオロメトキシ基である。）
で表される化合物であることが好ましく、下記式（６−１）：

（式中、Ｘ^３、Ｘ^４は、式（６）と同様である。）
で表される化合物であることがより好ましい。 More specifically, as the fluoroalkene, the following formula (6):

(Wherein, X ^{1 to} X ⁴ are each independently a trifluoromethyl group, a trifluoromethoxy group, a hydrogen atom, or a halogen atom. However, at least one of X ^{1 to} X ⁴ is A fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.)
It is preferable that it is a compound represented by following formula (6-1):

(Wherein X ³ and X ⁴ are the same as those in formula (6).)
It is more preferable that it is a compound represented by these.

Examples of the compound represented by the above formula (6) include CF ₂ = CFCF ₃ , CF ₂ = CF ₂ , CF ₂ = CFOCF ₃ , CFH = CF ₂ , CFH = CFCF ₃ , CH ₂ = CFCF ₃ , CH ₂ = CHCF ₃ , CH ₂ = CF _{2 and the} like. Among _{them, CF 2 = CFCF 3, CF} 2 = CF 2, CF 2 = CFOCF 3 are preferred.

Rf ¹ is preferably a group represented by the above formula (2) or formula (2-1).

Examples of the method of reacting the fluoroalkene with tetrahydrothiophene include a method of introducing the fluoroalkene into a liquid phase tetrahydrothiophene and causing the reaction. The reaction method can be any of batch method, semi-batch method, and flow method.

When the fluoroalkene is introduced into the liquid phase tetrahydrothiophene, the temperature at which the fluoroalkene is reacted with the tetrahydrothiophene is preferably 60 to 150 ° C, more preferably 80 to 150 ° C. The reaction pressure is preferably 0.5 to 1.0 MPa. Although reaction time changes with reaction temperature etc., it is 5 to 10 hours normally. Moreover, it is preferable to react by adding 0.1-8 mol of said fluoroalkene with respect to 1 mol of tetrahydrothiophene. More preferably, the input amount of the fluoroalkene is 0.2 to 6 moles, more preferably 0.2 to 5 moles, with respect to 1 mole of tetrahydrothiophene.

When the fluoroalkene is introduced into the liquid phase tetrahydrothiophene, the fluoroalkene may be reacted with the tetrahydrothiophene in the presence of a solvent inert to the tetrahydrothiophene and the fluoroalkene.

In the first production method of the present invention, it is preferable to add a reaction initiator to the reaction system and to react tetrafluorothiophene with a fluoroalkene having 2 to 8 carbon atoms. The reaction initiator is preferably added in an amount of 10 to 50 mol% with respect to the fluoroalkene. In the case of adding a reaction initiator to the reaction system, for example, the reaction initiator may be added in a reaction vessel in which tetrahydrothiophene is reacted with the fluoroalkene.

The reaction initiator is not particularly limited as long as it can perform the step of obtaining a compound represented by the formula (4) by reacting the tetrahydrothiophene with a fluoroalkene having 2 to 8 carbon atoms. For example, the reaction initiator is preferably at least one compound selected from the group consisting of organic peroxide initiators, radical polymerization initiators, and redox initiators.

Examples of the organic peroxide initiator include ditert-butyl peroxide, tert-butylcumyl peroxide, dicumyl peroxide, α, α-bis (tert-butylperoxy) -p-diisopropylbenzene, 2,5- Dialkyl peroxides such as dimethyl-2,5-di (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane-3, 1,1-di (tert-butyl) Peroxy) -3,3,5-trimethylcyclohexane, 2,5-dimethylhexane-2,5-dihydroxyperoxide, benzoyl peroxide, tert-butylperoxybenzene, 2,5-dimethyl-2,5-di (benzoylperoxy) Hexane, tert-butylperoxymaleic acid, Examples thereof include tert-butyl peroxysopropyl carbonate. Among these, dialkyl peroxides are preferable.

The radical polymerization initiator is preferably a water-soluble initiator, and specific examples thereof include persulfates such as ammonium persulfate, sodium persulfate, and potassium persulfate, disuccinic acid peroxide, azobisisobutylamidine dihydrochloride, and the like. Organic initiators and the like. Among these, persulfates such as ammonium persulfate are preferable.

Examples of redox initiators include organic initiators such as disuccinic acid peroxide and azobisisobutylamidine dihydrochloride, inorganic initiators such as persulfates and hydrogen peroxide, persulfates or hydrogen peroxide and hydroxy A redox initiator consisting of a combination with a reducing agent such as sodium methanesulfinate, sodium hydrogen sulfite, sodium thiosulfate, etc., and an inorganic start in which a small amount of iron, ferrous salt, silver sulfate, etc. coexist with these initiators Agents and the like. Among these, an ammonium persulfate / sodium hydroxymethanesulfinate / ferrous sulfate system is preferable, and it is more preferable to add ethylenediaminetetraacetic acid disodium salt as a chelating agent to this system. In addition, when using a redox-type initiator, it is preferable to use a pH buffer together.

As the pH buffering agent, inorganic salts such as disodium hydrogen phosphate, sodium dihydrogen phosphate, sodium hydrogen carbonate, sodium carbonate and the like can be used. Disodium hydrogen phosphate dihydrate, disodium hydrogen phosphate 12 A hydrate etc. are mentioned.

The step of reacting the compound represented by the above formula (4) with an oxidizing agent to obtain the fluorine-containing sulfolane represented by the formula (5) comprises reacting the compound represented by the above formula (4) with the oxidizing agent. It is preferable to carry out. For example, a method of introducing an oxidant into the compound represented by the above formula (4) in the liquid phase and reacting it may be mentioned. The reaction method can be any of batch method, semi-batch method, and flow method.

The oxidizing agent is not particularly limited as long as it is normally used as an oxidizing agent. For example, the oxidizing agent is preferably at least one compound selected from the group consisting of peroxides, perhalogen oxides, permanganates, and chromates. The oxidizing agent is preferably added in an amount of 100 to 500 mol% with respect to the compound represented by the formula (4).

Specific examples of the oxidizing agent include organic peroxides (for example, m-chloroperbenzoic acid), organic peracids, hydrogen peroxide, xylene dioxide, chromic acids, manganese dioxide, hypochlorous acids, and periodic acids. , Carolic acids, ceric ammonium nitrate (CAN), iodosobenzenes, and the like.

When an oxidant is introduced and reacted with the compound represented by the above formula (4) in the liquid phase, the oxidation reaction is preferably performed at 25 to 80 ° C, more preferably at 30 to 80 ° C. . Although reaction time changes with reaction temperature etc., it is 5 to 10 hours normally.

Hereinafter, the second manufacturing method will be described.

（式中、Ｘ^６は、フッ素原子、塩素原子、臭素原子、又は、ヨウ素原子である。）
で示される５−ハロゲン−１−ペンテンを、Ｒｆ^２Ｘ^５（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基であり、Ｘ^５は、塩素原子、臭素原子、又はヨウ素原子である。）
で表される化合物と反応させて、下記式（７）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基であり、Ｘ^６は、フッ素原子、塩素原子、臭素原子、又は、ヨウ素原子であり、Ｘ^５は、塩素原子、臭素原子、又は、ヨウ素原子である。）で表される化合物を得る工程、
上記式（７）で表される化合物を、チオール化剤と反応させて、下記式（８）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基であり、Ｘ^５は、塩素原子、臭素原子、又は、ヨウ素原子である。）で表される化合物を得る工程、
上記式（８）で表される化合物を環化反応させて、下記式（９）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基である。）
で表される化合物を得る工程、及び、
上記式（９）で表される化合物を酸化剤と反応させて、下記式（１０）：

（式中、Ｒｆ^２は、ヘテロ原子を含んでいてもよい炭素数１〜７のフルオロアルキル基である。）
で表される含フッ素スルホランを得る工程を含むものである。 The second production method of the present invention has the following formula:

(In the formula, X ⁶ is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.)
Rf ² X ⁵ (wherein Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom, and X ⁵ is a chlorine atom. , Bromine atom, or iodine atom.)
Is reacted with a compound represented by the following formula (7):

(In the formula, Rf ² is a C1-C7 fluoroalkyl group that may contain a hetero atom, X ⁶ is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X ⁵ Is a chlorine atom, a bromine atom, or an iodine atom.)
The compound represented by the above formula (7) is reacted with a thiolating agent to obtain the following formula (8):

(In the formula, Rf ² is a C1-C7 fluoroalkyl group which may contain a hetero atom, and X ⁵ is a chlorine atom, a bromine atom or an iodine atom). Obtaining a compound;
The compound represented by the above formula (8) is cyclized to give the following formula (9):

(In the formula, Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom.)
A step of obtaining a compound represented by:
The compound represented by the above formula (9) is reacted with an oxidizing agent to obtain the following formula (10):

(In the formula, Rf ² is a C 1-7 fluoroalkyl group which may contain a hetero atom.)
The process of obtaining the fluorine-containing sulfolane represented by these is included.

In the second production method of the present invention, the fluorine-containing sulfolane represented by the above formula (10) can be produced by a simple method and is not fluorinated with fluorine gas. And fluorine-containing sulfolane having high stability can be produced.

Halogen (X ⁶ ) in 5-halogen-1-pentene is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and among these, a bromine atom is preferable.

Rf ² is a fluoroalkyl group having 1 to 7 carbon atoms. Rf ² is a linear or branched fluoroalkyl group. Rf ² may be an alkyl group in which at least one hydrogen atom is substituted with a fluorine atom, and may be a perfluoroalkyl group. Moreover, the hetero atom may be included.

Examples of Rf ² include fluoroalkyl groups such as a fluoromethyl group, a fluoroethyl group, a fluoropropyl group, a fluorobutyl group, a fluoropentyl group, and a fluorohexyl group. These fluoroalkyl groups may be linear or branched. Further, it may be a perfluoroalkyl group.

More _{specifically, - (CF 2) n H} (n is an integer of _{1~7), - (CF 2)} m CF 3 (m is an integer from 1 to 6), - CF ( CF ₃ ) ₂ , —CH (CF ₃ ) _{2 and the} like. More _{preferably, -C 4 F 9, -C 2} F 5, -CF 3, and at least one selected from -CF _{(CF 3) 2.}

Examples of the method of reacting 5-halogen-1-pentene with a compound represented by Rf ² X ⁵ (wherein Rf ² and X ⁵ are the same as those described above) include, for example, liquid-phase 5-halogen-1- Examples thereof include a method in which the compound represented by Rf ² X ⁵ is introduced into pentene and reacted. The reaction method can be any of batch method, semi-batch method, and flow method.

When using a method of reacting by introducing the compound represented by ^Rf 2 ^{X 5} in the liquid phase 5 halogen-1-pentene, 5-halogen-1-pentene, a compound represented by ^Rf 2 ^{X 5} As a temperature which makes this react, 50-80 degreeC is preferable, More preferably, it is 60-80 degreeC. Moreover, as a compounding ratio of the 5-halogen-1-pentene and the compound represented by Rf ² X ⁵ in the above reaction, a molar ratio of 1: 1 to 1: 1.5 is preferable. More preferably, it is 1: 1 to 1: 1.2.

Although reaction time changes with reaction temperature etc., it is 5 to 10 hours normally. In the case of using a method in which a compound represented by Rf ² X ⁵ is introduced into 5-halogen-1-pentene and reacted, with respect to the compound represented by 5-halogen-1-pentene and Rf ² X ⁵ The reaction may be carried out in the presence of an inert solvent.

The second production method of the present invention includes a step of reacting the compound represented by the above formula (7) with a thiolating agent to obtain the compound represented by the above formula (8). Examples of the thiolating agent include thioalkoxide, thiourea, thiouric acid and the like.
Moreover, as addition amount of a thiol agent, it is preferable that it is 1-1.5 mol with respect to 1 mol of compounds represented by Formula (7). More preferably, it is 1-1.2 mol with respect to 1 mol of compounds represented by Formula (7) as addition amount of a thiolating agent.

The second production method of the present invention includes a step of obtaining a compound represented by the above formula (9) by cyclizing the compound represented by the above formula (8).

Examples of the method for carrying out the cyclization reaction include a method in which an alkali solution is added to a solution containing a compound represented by the formula (8) to carry out the reaction. Examples of the method of adding the alkaline solution include a method of adding all at once, a method of intermittently adding several times before or during the reaction, and a method of continuously dropping before or during the reaction. Any method may be used, but it is preferably added by a method of continuously dropping before or during the reaction.

Examples of the alkaline solution include LiOH, NaOH, KOH, RbOH, CsOH, Be (OH) ₂ , Mg (OH) ₂ , Ca (OH) ₂ , Sr (OH) ₂ , Ba (OH) _{2, and the} like. Is mentioned. Among these, a solution of LiOH, NaOH, KOH is preferable. Particularly preferred are an aqueous sodium hydroxide solution and an aqueous potassium hydroxide solution.
Moreover, as a density | concentration of the said alkali solution, it is preferable that it is 20-40 mass%, More preferably, it is 20-30 mass%.

As the addition amount of the alkaline solution in the cyclization reaction, it is preferable to add 1.2 to 4 mol with respect to 1 mol of the compound represented by the formula (8). More preferably, it is 1.2-2 mol, More preferably, it is 1.2-1.5 mol.

The temperature for the cyclization reaction is preferably 50 to 100 ° C, more preferably 60 to 100 ° C. Although reaction time changes with reaction temperature etc., it is 5 to 10 hours normally. The reaction method can be any of batch method, semi-batch method, and flow method.

The 2nd manufacturing method of this invention includes the process of oxidizing the compound represented by the said Formula (9), and obtaining the fluorine-containing sulfolane represented by the said Formula (10).

The oxidation is preferably performed by reacting the compound represented by the formula (9) with an oxidizing agent. For example, a method of introducing an oxidant into the compound represented by the above formula (9) in the liquid phase and reacting it may be mentioned. The reaction method can be any of batch method, semi-batch method, and flow method.

The oxidizing agent is not particularly limited as long as it is normally used as an oxidizing agent. For example, the oxidizing agent is preferably at least one compound selected from the group consisting of peroxides, perhalogen oxides, permanganates and chromates. The oxidizing agent is preferably added so as to be 2 to 4 times (molar ratio) with respect to the compound represented by the formula (9).

When an oxidant is introduced into the compound represented by the formula (9) in the liquid phase and reacted, the oxidation is preferably performed at 25 to 100 ° C, more preferably at 50 to 100 ° C. Although reaction time changes with reaction temperature etc., it is 5 to 10 hours normally.

The fluorine-containing sulfolane of the present invention can be used as various solvents, for example, reaction solvents for organic synthesis, extraction solvents for various inorganic and organic substances, dilution solvents for paints and inks, semiconductor resist solvents, dilution solvents for agricultural chemicals, etc. It can be used as a solvent for an electrolytic solution used in an energy storage device or the like. It can also be used as an additive for electrolytes used in energy storage devices and the like. In particular, it is useful as a solvent or additive for an electrolytic solution for an energy storage device.

The present invention also provides an electrolytic solution containing the above-mentioned fluorine-containing sulfolane or the fluorine-containing sulfolane obtained by the above-described production method. The electrolytic solution preferably contains an electrolyte salt. Examples of the electrolyte salt include LiClO ₄ , LiAsF ₆ , LiBF ₄ , LiPF ₆ , LiN (SO ₂ CF ₃ ) ₂ , and LiN (SO ₂ C ₂ F ₅ ) ₂ .

Applications of the electrolytic solution using the fluorine-containing sulfolane of the present invention include, for example, an electrolytic capacitor, an electric double layer capacitor, a battery charged / discharged by charge transfer of ions, a solid display element such as electroluminescence, a current sensor and a gas Examples include sensors such as sensors.

Especially, it is preferable to use for a lithium ion secondary battery, and the electrolytic solution of the present invention is suitably used for a lithium ion secondary battery including a positive electrode, a negative electrode, a separator, and a nonaqueous electrolytic solution containing the electrolytic solution of the present invention. be able to. Such a lithium ion secondary battery is particularly useful as a large lithium ion secondary battery for a hybrid vehicle or a distributed power supply, but is also useful as a small lithium ion secondary battery.

Next, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited to such examples.

NMR: using BRUKER AC-300
¹⁹ F-NMR:
Measurement conditions: 282 MHz (trichlorofluoromethane = 0 ppm)
¹ H-NMR:
Measurement conditions: 300 MHz (tetramethylsilane = 0 ppm)

Example 1
1) 1 step (addition reaction)
The reaction was carried out in a reactor equipped with a 300 mL reflux tube. 5-Bromo-1-pentene (25 g: 168 mmol), C ₄ F ₉ I (65.7 g: 190 mmol), azobisisobutyronitrile (hereinafter referred to as AIBN, 551 mg: 3.4 mmol) in the reaction vessel in this order. Reagent added. Thereafter, the reaction temperature was increased to around 70-80 ° C. Although it gradually became under reflux, the reflux stopped with the progress of the reaction. After stirring for 1 hour, the reaction was completed after confirming the disappearance of the raw materials. Thereafter, only the low boiling point compound was removed under reduced pressure to proceed to the next reaction.

2) Two steps (thiolation + cyclization reaction)
To the above solution, thiourea (12.8 g: 168 mmol) and 35 mL of ethanol were added and stirred under reflux. When confirmed by gas chromatography (GC), it was confirmed that the raw material disappeared and Br became SH. Then, the cyclization reaction was performed by adding 120 g of 30 mass% KOH aqueous solution with a dropping funnel (80 degreeC, 5 hours). The desired product was collected by distillation.

3) 3 steps (oxidation reaction)
The cyclized compound (43 g: 134.4 mmol) was dissolved in acetic acid (45 g), and then a 30 mass% H ₂ O ₂ aqueous solution (45 ml: 403.2 mmol) was added dropwise at 100 ° C. After the reaction, the lower layer separated into two layers was extracted and washed with pure water, and a solid was deposited. The solid was purified by distillation. The yield of the obtained target product was 72%.

The NMR data of the obtained compound 1 are as follows.

¹⁹ F-NMR: (acetone): −80.20 to −82.00 ppm (3F), −110.00 to −115.0 ppm (2F), −122.5 to −125.22 ppm (2F), −125 .13 to -130.22 ppm (2F)

¹ H-NMR: (acetone): 1.50-4.00 ppm (9H)

Examples 2-4
The target product could be obtained in the same manner as in Example 1 except that the amount of compound shown in Table 1 was added.

Example 5
1) 1 step (addition reaction)
The reaction was carried out using an autoclave, which is a pressure-resistant reaction vessel. Add tetrahydrothiophene (100 g: 1.136 mol) and initiator perbutyl D (16.7 g: 114 mmol, manufactured by NOF Corporation, di-tert-butyl peroxide), fill with hexafluoropropylene to 0.3 MPa, and apply heat. The reaction temperature was raised. Gradually, heat generation was confirmed at around 120 ° C., and a decrease in pressure was also confirmed. Hexafluoropropylene was continuously added up to a limit of 0.6 MPa.
The reaction was terminated when it was determined that there was no pressure drop. The reaction solution was taken out and the target product was collected by distillation. The total amount of hexafluoropropylene charged was 40 g (267 mmol).

2) Two steps (oxidation reaction)
51 g (213 mmol) of the obtained product was dissolved in 20 g of a trifluoroacetic acid solvent, and an oxidation reaction was performed with 75 mL (675.0 mmol) of a 30% by mass H ₂ O ₂ aqueous solution (30 ° C., 5 hours). Thereafter, the reaction solution was distilled by the following purification step.

(Purification process)
After distillation, the resulting pale yellow solid was dissolved by applying heat to toluene. Thereafter, after cooling gradually, solid deposition was confirmed. In the slurry state, an amount of hexane equivalent to toluene was added and stirred, and after stirring for about 1 hour, the crystals were filtered using a Kiriyama funnel. The collected crystal was dried in vacuum.

The NMR data of the obtained compound 5 are as follows.

¹⁹ F-NMR: (acetone): −209.91 to −209.105 ppm (1F), −113.20 to −112.9 ppm, −111.90 to −111.7 ppm, −110.7 to −110. 6 ppm, -110.00 to -109.8 ppm, -109.68 to -109.4 ppm, -108.999 to -108.4 ppm, -106.60 to -106.34 ppm, -105.38 to -105. 29 ppm (2F), -76.52 to -74.128 ppm (3F)

¹ H-NMR: (acetone): 1.82 to 2.10 ppm (1H), 2.40 to 2.66 ppm (4H), 3.14 to 3.18 ppm (1H), 3.40 to 3.67 ppm ( 1H), 4.78 to 5.23 ppm (1H)

Examples 6 and 7
The target product could be obtained in the same manner as in Example 5 except that the amount of compound shown in Table 2 was added.

Oxidation resistance test (preparation of electrolyte)
The fluorine-containing sulfolane, propylene, and propylene carbonate (PC) obtained in Examples 1 to 7 were made fluorine-containing sulfolane: PC = 80: 20% by volume, and 0.1 mol% of LiPF ₆ was dissolved in this mixed solution. A solution was prepared. As a comparative example, sulfolane was used instead of fluorine-containing sulfolane.

(Measurement of potential window)
The electrolyte solution is put in a three-electrode voltage measuring cell (working electrode: platinum, counter electrode: Li, reference electrode: Li, HS cell manufactured by Hosen Co., Ltd.), and the potential is run at 3 mV / sec with a potentiostat. The decomposition current was measured. Table 3 shows the measurement results.

Moreover, the following test was done by adjusting a non-aqueous electrolyte using the compound 5 obtained in Example 5. The results are shown in Table 4.

Test (measurement of battery characteristics)
A cylindrical secondary battery was produced by the following method.

A positive electrode active material obtained by mixing LiCoO ₂ , carbon black and polyvinylidene fluoride (manufactured by Kureha Chemical Co., Ltd., trade name: KF-1000) at 90/3/7 (mass%) was added to N-methyl-2-pyrrolidone. What was dispersed and made into a slurry form was uniformly applied onto a positive electrode current collector (aluminum foil having a thickness of 15 μm) and dried to form a positive electrode mixture layer. Then, after compression-molding with a roller press machine, it cut | disconnected and the lead body was welded and the strip | belt-shaped positive electrode was produced.

Separately, styrene-butadiene rubber dispersed with distilled water was added to artificial graphite powder so as to have a solid content of 6% by mass, and mixed with a disperser to form a slurry. A negative electrode current collector (thickness 10 μm) On the copper foil) and dried to form a negative electrode mixture layer, and then compression molded with a roller press and cut. Then, it dried and welded the lead body and produced the strip | belt-shaped negative electrode.

The belt-like positive electrode was overlapped with the belt-like negative electrode through a microporous polyethylene film (separator) having a thickness of 20 μm and wound in a spiral shape to obtain a laminated electrode body having a spiral winding structure. In that case, it wound so that the rough surface side of the positive electrode current collector could be the outer peripheral side. Thereafter, the electrode body was filled in a bottomed cylindrical battery case having an outer diameter of 18 mm, and the positive and negative lead bodies were welded.

Next, a nonaqueous electrolyte solution described later was poured into the battery case, and after the electrolyte solution sufficiently penetrated into the separator and the like, it was sealed, precharged, and aged to produce a cylindrical lithium secondary battery.

The lithium secondary battery was examined for discharge capacity, load characteristics (high temperature storage characteristics) and cycle characteristics in the following manner. The results are shown in Table 4.

(Discharge capacity)
When the charge / discharge current is represented by C, measurement is performed under the following charge / discharge measurement conditions with 1800 mA as 1C. The evaluation is performed using an index with the result of the discharge capacity of the comparative electrolyte described later as 100.

Charging / Discharging Condition Charging: Holds until the charging current becomes 1 / 10C at 1.0C, 4.5V (CC / CV charging)
Discharge: 1C 3.0Vcut (CC discharge)

(High temperature storage characteristics)
Regarding charging, the battery was charged at 1.0 C at 4.5 V until the charging current became 1/10 C, discharged at a current equivalent to 0.2 C to 3.0 V, and the discharge capacity was determined. Thereafter, the battery was charged at 1.0 C and 4.5 V until the charging current became 1/10 C, and placed in a constant temperature bath at 85 ° C. for 2 days. Two days later, the battery was sufficiently placed to cool to room temperature and discharged at a current corresponding to 0.2 C until 3.0 V was reached. Thereafter, the battery was charged at 1.0 C at 4.5 V until the charging current became 1/10 C and discharged at a current equivalent to 0.2 C until 3.0 V, and the discharge capacity after storage was determined. The discharge capacity before storage and the discharge capacity charged after storage and discharged at 0.2 C were substituted into the following calculation formula to obtain high temperature storage characteristics.

(Cycle characteristics)
As for the cycle characteristics, the charge / discharge cycle performed under the above charge / discharge conditions (charging at 1.0 C until the charging current becomes 1/10 C at 4.5 V and discharging to 3.0 V at a current equivalent to 1 C) is 1 The discharge capacity after the first cycle and the discharge capacity after 100 cycles were measured. For the cycle characteristics, the value obtained by the following formula was used as the cycle retention rate.

(Preparation of non-aqueous electrolyte)
Ethylene carbonate, dimethyl carbonate, and the compound 5 obtained in Example 5 were mixed so as to have a ratio of 30/67/3 volume%, and 1.0 mol of LiPF ₆ was further added as an electrolyte salt to the solvent for non-aqueous electrolyte. A non-aqueous electrolyte was prepared by stirring sufficiently at 25 ° C.

(Preparation of comparative electrolyte)
Ethylene carbonate and diethyl carbonate are mixed so as to be 30/70 (volume%), and LiPF ₆ is further added to this solvent as an electrolyte salt so as to have a concentration of 1.0 mol / liter. And a comparative electrolytic solution was prepared.

Since the fluorine-containing sulfolane of the present invention is excellent in oxidation resistance and exhibits high electrochemical stability, it can be suitably used for various applications. The fluorine-containing sulfolane of the present invention is particularly useful as a solvent or additive for an electrolyte solution for an energy storage device, for example. The method for producing fluorine-containing sulfolane of the present invention can easily and reliably produce fluorine-containing sulfolane having excellent oxidation resistance.

Claims (8)

Following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
In expressed,
Rf is the following formula (2):

( Wherein , X ^{1 to} X ⁴ are each independently a trifluoromethyl group, a trifluoromethoxy group, a hydrogen atom, or a halogen atom. However, at least one of X ^{1 to} X ⁴ is A fluorine atom, a trifluoromethyl group, or a trifluoromethoxy group.)
A fluorine-containing sulfolane. Rf _{is, -CF 2 CFHOCF 3, -CH 2} CFHCF 3, -CH 2 CH 2 CF 3, -CFHCF 2 H, -CFHCFHCF 3, -CF 2 CF 2 H, -CH 2 CF 2 H, and, -CF at least one fluorine-containing sulfolane as claimed in claim 1, wherein is a group selected from the group consisting of ₂ CFHCF _3. Electrolytic solution comprising a fluorine-containing sulfolane as claimed in claim 1 or 2, wherein. Following formula (3):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by the following formula (1):

(In the formula, Rf is a C1-C8 fluoroalkyl group which may contain a hetero atom.)
In obtaining a fluorine-containing sulfolane represented, only including,
The compound represented by the formula (3) is represented by the following formula (4):

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by
The fluorine-containing sulfolane represented by the formula (1) is represented by the following formula (5):

(In the formula, Rf ¹ is a C 2-8 fluoroalkyl group which may contain a hetero atom.)
A compound represented by
Further comprising the step of reacting tetrahydrothiophene with a C2-C8 fluoroalkene to obtain a compound represented by the formula (4),
The fluoroalkene _{is, CH 2 = CFCF 3, CH} 2 = CH-CF 3, CF 2 = CF-OCF 3, CFH = CFCF 3, CFH = CF 2, CH 2 = CF 2, CF 2 = CF 2 and, CF 2 ₌ CFCF at least one fluorine-containing sulfolane manufacturing method comprising <br/> is a _{compound 3} selected from the group consisting of. The method for producing fluorine-containing sulfolane according to claim 4 , wherein the oxidizing agent is at least one compound selected from the group consisting of peroxides, perhalogen oxides, permanganates, and chromates. The following formula:

(Where X ⁶ Is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. ) -Halogen-1-pentene (halogen: fluorine atom, chlorine atom, bromine atom or iodine atom) represented by Rf ² X ⁵ (Where Rf ² Is a C 1-7 fluoroalkyl group which may contain a hetero atom, and X ⁵ Is a chlorine atom, a bromine atom, or an iodine atom. )
Is reacted with a compound represented by the following formula (7):

(Where Rf ² Is a C 1-7 fluoroalkyl group which may contain a hetero atom, and X ⁶ Is a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom, and X ⁵ Is a chlorine atom, a bromine atom, or an iodine atom. A step of obtaining a compound represented by
The compound represented by the formula (7) is reacted with a thiolating agent to obtain the following formula (8):

(Where Rf ² Is a C 1-7 fluoroalkyl group which may contain a hetero atom, and X ⁵ Is a chlorine atom, a bromine atom, or an iodine atom. And a step of obtaining a compound represented by:
The compound represented by the formula (8) is cyclized to give the following formula (9):

(Where Rf ² Is a C1-C7 fluoroalkyl group which may contain a hetero atom. )
A step of obtaining a compound represented by:
The compound represented by the formula (9) is reacted with an oxidizing agent to obtain the following formula (10):

(Where Rf ² Is a C1-C7 fluoroalkyl group which may contain a hetero atom. )
A process for producing a fluorinated sulfolane represented by the formula: Rf ² is — (CF ₂ ) _n H (n is an integer of 1 to 7), — (CF ₂ ) _m CF ₃ (m is an integer of 1 to 6), —CF (CF ₃ ) ₂ and at least one group selected from the group consisting of —CH (CF ₃ ) _{2. The} method for producing a fluorine-containing sulfolane according to claim 6 . The method for producing fluorine-containing sulfolane according to claim 6, wherein the oxidizing agent is at least one compound selected from the group consisting of peroxides, perhalogen oxides, permanganates, and chromates.