JP2010270071A - Cation raw material for ionic fluid and process for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cation raw material linking a sulfonic acid group and a phosphonic acid group which is useful in synthesizing an ionic fluid to be used in a lithium-ion battery, a fuel cell electrolyte or a solvent for recovering rare earth metals. <P>SOLUTION: The cation raw material for an ion fluid includes the chemical structure: (X)<SB>m</SB>-Y-fullerene-(Z)<SB>n</SB>(wherein X is an imidazole group or a benzimidazole group; Y is S or SO<SB>2</SB>; Z is a sulfonic acid group, a phosphonic acid group or a precursor thereof; m is an integer of 1-4; n is an integer of 1-10; and m+n=2-12). A process for producing the cation raw material for an ion fluid comprises (step 1) a step of bonding an imidazole group or a benzimidazole group to fullerene, (step 2) a step of bonding a sulfonic acid group, a phosphonic acid group or a precursor thereof to the fullerene, and if necessary, (step 3) a step of oxidizing the sulfide bond into a sulfone bond. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cation raw material useful for synthesizing an ionic liquid used as an electrolyte or a rare metal recovery solvent for lithium ion batteries and fuel cells, and a method for producing the same.

Ionic liquid has characteristics such as low melting point, high heat resistance, non-volatility, high ionic conductivity, wide potential window, layer separation from water phase, etc., as an electrolyte or reaction / extraction solvent for lithium ion batteries and fuel cells Recently attracted attention.
The ionic liquid is composed of an organic cation such as imidazolium ion, pyridinium ion, tetraalkylammonium ion or tetraalkylphosphonium ion, and an anion such as BF ₄ , PF ₆ , CF ₃ SO ₃ , (CF ₃ SO ₂ ) ₂ N or the like. Has been.

Since the cation is an organic compound, it can be designed according to the purpose. However, conventionally, there has been no cationic raw material that can fully utilize its characteristics.
For example, an imidazolium ion having a sulfonic acid group for use in an electrolyte of a fuel cell (see Patent Document 1) uses an alkyl sultone to introduce a sulfonic acid group, so that only one sulfonic acid group can be introduced. As many as four methylene groups with low chemical properties are introduced. Further, it is impossible to introduce a phosphonic acid group, which is an ion exchange group necessary for insolubilization by metal ion crosslinking and use of Ce ions which are OH radical scavengers (see Patent Document 2 relating to the present inventor's invention).

  The inventor has prepared a method for producing a chemically modified fullerene having a sulfonic acid group or a phosphonic acid group bonded thereto (see Patent Document 3 relating to the inventor's invention) and a method for producing an imidazolated fullerene (species relating to the inventor's invention) Application of Japanese Patent Application No. 2007-305494) to synthesize chemically modified fullerene in which an imidazole group or a benzimidazole group is bonded to a fullerene and a sulfonic acid group, a phosphonic acid group or a precursor thereof is bonded to the fullerene. Thus, the present invention was completed by realizing a cation raw material for ionic liquid capable of introducing a plurality of sulfonic acid groups and phosphonic acid groups.

In order to synthesize an ionic liquid using the cation raw material of the present invention, first, the imino group at the 1-position of the imidazole ring is changed to NM using MH (where M is Li, Na or K), This is achieved by reacting to a tertiary amine and then quaternizing the tertiary amine at the 3-position into the imidazolium cation by the following known method (see Non-Patent Document 1).
(1) Anion exchange method (2) Acid ester method (3) Neutralization method

International Publication No. 2006/025482 JP 2009-045771 A Japanese Patent No. 3984280

Tomoya Kitazume, Toshio Sujoue, Hideo Sawada, Toshiyuki Ito, “Ionic Liquids: Mysterious Salts that Overturn Common Senses”, Corona, 2005, p.6-10

  An object of the present invention is to provide a cation raw material capable of introducing a plurality of sulfonic acid groups and phosphonic acid groups into an ionic liquid used as an electrolyte or a rare metal recovery solvent for lithium ion batteries and fuel cells.

In order to solve the above problems, the present invention is a cation raw material for an ionic liquid having a chemical structure of (X) _m -Y-fullreene- (Z) _n (where X is an imidazole group or a benzimidazole group; Y is S or SO ₂ ; Z is a sulfonic acid group, phosphonic acid group or a precursor thereof; m is an integer of 1 to 4; n is an integer of 1 to 10; m + n = 2 to 12).

Further, in order to solve the above-mentioned problems, the present invention is a method for producing a cation raw material for ionic liquid as described above, wherein the mercapto group of 2-mercaptoimidazole or 2-mercaptobenzimidazole is SM by MH in dioxane or dimethylacetamide. And a step of binding an imidazole group or a benzimidazole group to fullerene, which is reacted with fullerene at normal pressure or under pressure at 20 to 200 ° C. for 10 to 200 hours, where M is Li, Na or K, and sulfone In the case of the oxidizing reagent M ₂ SO ₃ (dimethylacetamide + water), in the case of the phosphonating reagent MPO (OR) ₂ , a specific reaction solvent of dioxane is selected, and in the solvent, fullerene and M ₂ SO ₃ or MPO ( _{OR) 2} and allowed to disperse, normal pressure or under pressure, with a reaction temperature of 20 to 200 ° C. Reacting 0-200 hours, a sulfonic acid group, a phosphonic acid group or its precursor step that binds to the fullerene (here, M is Li, Na or K; R is an alkyl group or a phenyl group of _C 1 -C ₅₎ Including.

The above production method is carried out using an oxidizing agent such as hydrogen peroxide, peracetic acid, potassium permanganate, sodium perborate and the like under reaction pressure of 20 to 200 ° C. for 10 to 200 hours under normal pressure or pressure. the X-S-fullerene may further comprise the step of oxidizing the _X-SO 2 _-fullerene.

By using the cation raw material of the present invention, the conductivity of lithium ions and protons is increased in ionic liquids used as electrolytes for lithium ion batteries and fuel cells, and insolubilization by metal ion crosslinking and Ce ions of OH radical scavengers. It is possible to introduce a plurality of sulfonic acid groups or phosphonic acid groups for the purpose of utilizing the above.
Moreover, since the cation raw material of this invention has the phosphonic acid group for metal ion bridge | crosslinking, it can be used also for the synthesis | combination of the ionic liquid used as a solvent for rare metal collection | recovery.

The present invention is a cation raw material for an ionic liquid having a chemical structure of (X) _m -Y-fullrene- (Z) _n (where X is an imidazole group or a benzimidazole group; Y is S or SO ₂ ; Z Is a sulfonic acid group, a phosphonic acid group or a precursor thereof; m is an integer of 1 to 4; n is an integer of 1 to 10; m + n = 2 to 12).

In the above structural formula, the number of bonds m is preferably 1 or 2. The number n of bonds is preferably in the range of 2 to 7, and one type of sulfonic acid group, phosphonic acid group or precursor thereof may be bonded to fullerene, or a plurality of types may be mixed and bonded. Good.
Further, the number of bonds m and n may be substantially single after purification, or a mixture of those having different numbers of bonds m and n may be used. It is possible to make (m + n) larger than 12 by devising reaction conditions.

As the fullerene of the substrate, fullerenes such as C ₆₀ , C ₇₀ , C ₇₆ , C ₇₈ , and C ₈₄ can be used, or a mixture thereof can also be used. In _particular, obtained by the manufacturing process of _{C 60, C 60} 50 to 90% before _{purification, C 70} is 40 to 10%, preferably a so material cost becomes cheaper higher fullerenes is a mixture of 10% or less is there.
In the present invention, the sulfonic acid group precursor includes a sulfonyl halide group or a sulfonic acid ester group, and the phosphonic acid group precursor includes a phosphonic acid ester group. These precursors can be converted into sulfonic acid groups or phosphonic acid groups by hydrolysis, but in some cases, they may be used as they are.

  The method for producing a cation raw material of the present invention includes the following (Step 1) and (Step 2), and (Step 3) as necessary.

(Process 1)
The mercapto group of 2-mercaptoimidazole or 2-mercaptobenzimidazole is changed to SM by MH in dioxane or dimethylacetamide, and reacted with fullerene at normal pressure or under pressure at 20 to 200 ° C. for 10 to 200 hours. A step of bonding an imidazole group to fullerene (where M is Li, Na or K).

In the above process, the mercapto group at the 2-position bonded to the imidazole ring is more acidic than the imino group at the 1-position, so it is preferentially changed to SM and added to the fullerene double bond as shown in the following formula. . In this case, the carbanion produced as an intermediate is stabilized by extracting H from the reaction solvent.

As the solvent used in the reaction, an aprotic polar organic solvent such as dioxane or dimethylacetamide is preferably used. Tetrahydrofuran can also be used, but dioxane is preferred because the boiling point is low and the reaction temperature cannot be increased.
Further, even in the same amide solvent, dimethylformamide is preferably added to fullerene, so that dimethylacetamide is preferably used.

(Process 2)
In the case of the sulfonating reagent M ₂ SO ₃ (dimethylacetamide + water), in the case of the phosphonating reagent MPO (OR) ₂ , a specific reaction solvent of dioxane is selected, and in the solvent, fullerene and M ₂ SO ₃ or MPO are selected. (OR) ₂ is a step of dispersing a sulfonic acid group, a phosphonic acid group or a precursor thereof to fullerene by dispersing ₂ and reacting at normal pressure or under pressure using a reaction temperature of 20 to 200 ° C. for 10 to 200 hours. (here, M Li, Na or K; R is an alkyl group or a phenyl group of _C 1 _{~C 5).}

The table below shows the reaction results of fullerene and the sulfonating reagent by the above steps.
In the case of the solvent bond in the table, a side reaction occurs in which an organic compound derived from the reaction solvent is bonded to fullerene, which is not preferable. In this case, a complex peak appears in the infrared absorption spectrum of the product, and it can be easily distinguished from the product of the target reaction showing a simple spectrum.
By the way, DMF is (CH ₃ ) ₂ NCOH, DMAc is (CH ₃ ) ₂ NCOCH ₃ and belongs to the same amide solvent. It is a surprising discovery that it is completely different, which is the reason for selecting a specific reaction solvent in the above process.

Here, one reason for adding water to the reaction solvent is to increase the solubility of the sulfonating reagent in the organic solvent. Another reason for adding water is that, as shown in the following formula, the carbanion produced during the reaction is stabilized by extracting protons from the water before binding to the solvent molecules.

The SO ₃ M type obtained after the reaction can be converted into an SO ₃ Li type for a lithium ion battery or an SO ₃ H type for a fuel cell by an ion exchange method, if necessary.

The phosphonating reagent MPO (OR) ₂ used in the above step is prepared by the following reaction using an aprotic polar organic solvent and usually at 20 to 100 ° C.

Phosphonation reaction is carried out by adding fullerene to this, but when dimethylformamide is used as a solvent, solvent bonding occurs, and it was found from the infrared absorption spectrum analysis of the product that dioxane must be used.
In this case, it is possible to use the same cyclic ether-based tetrahydrofuran, but it is preferable to use dioxane because the reaction temperature is lowered because the boiling point is low.

The carbanion produced during the phosphonation reaction is stabilized by extracting a proton from the alkyl group of the solvent dioxane or phosphonate.

The phosphonic acid ester group obtained by the phosphonation reaction is reacted with trimethylsilyl bromide by a known method for transesterification, and then hydrolyzed by adding water to convert it to the phosphonic acid group PO (OH) ₂ . be able to. The hydrolysis of the phosphonate group can also be carried out in hot concentrated hydrochloric acid.
In addition, the sulfonic acid oxidation reaction is performed by the above-described method, the sulfonic acid group is bonded in advance, and then the phosphonic acid ester group is bonded to synthesize a chemically modified fullerene in which the sulfonic acid group and the phosphonic acid group coexist. It is also possible to do. In this case, it is also possible to reverse the reaction sequence and first bind the phosphonate ester group and then the sulfonic acid group.

(Process 3)
Using an oxidizing agent such as hydrogen peroxide, peracetic acid, potassium permanganate, sodium perborate or the like, under normal pressure or under pressure, reaction conditions of 20 to 200 ° C. for 10 to 200 hours are used to treat X-S-fullrene. step of oxidizing the _X-SO 2 -fullerene.

  The reaction solvent in the above process varies depending on the type of oxidizing agent. For hydrogen peroxide and peracetic acid, methanol, acetic acid, trifluoroacetic acid, for potassium permanganate, water and water / methylene chloride, for sodium perborate, methanol, etc. Are preferably used.

The order in which the above-described three steps are performed takes various variations, such as step 1-step 2- (step 3), step 2-step 1- (step 3), step 1- (step 3) -step 2. It is possible to select appropriately according to the object.
Examples are shown below, but the present invention is not limited thereto.

Example 1
A 300 ml three-necked flask was charged with 720 mg of fullerene C ₆₀ and 200 ml of dimethylacetamide. To this was added 790 mg of potassium sulfite K ₂ SO ₃ (5 mol of fullerene) dissolved in 10 ml of water, and the mixture was heated and stirred at 80 ° C. for 4 days.
After completion of the reaction, the solvent was removed by drying and the residue was extracted with ethanol. The solid was filtered off, after which the filtrate ethanol was removed by drying, The infrared absorption spectrum was measured using a KBr, SO ₂ stretch the 1117Cm ^-1, appeared peaks of CS stretch to 619cm ^-1.

Further, S, K analysis was performed by ICP-AES (inductively coupled plasma atomic emission spectrum method), and elemental analysis of C, H, O by combustion method was C57.5%, S11.4%, K14. 7%, H0.55%, and O13.0%, and it was confirmed that about 4 to 5 sulfonic acid groups SO ₃ K and H were bonded.
Furthermore, when the sample was dissolved in D ₂ O and NMR was measured, a peak presumed to be a proton at the beta position was confirmed. The yield of the sulfonated fullerene obtained was approximately 30% on a fullerene basis.

In a 300 ml three-necked flask, 80 g of dioxane was added, 0.4 g of 2-mercaptoimidazole and 0.05 g of lithium hydride were added, and the mixture was stirred at 50 ° C. After generation of hydrogen bubbles ceased, 1.4 g of the fullerene having the sulfonic acid group SO ₃ K bound thereto was added and stirred at 80 ° C. for 2 nights. As a result, the reacted fullerene was dissolved in the solvent.
After completion of the reaction, unreacted sulfonated fullerene was removed by filtration, the dioxane in the filtrate was removed by evaporation using an evaporator, the residue was washed with methanol, and the infrared absorption spectrum was measured using KBr. In the obtained IR, in addition to the absorption of the sulfonic acid group described above, absorption specific to the imidazole group was observed at 2500 to 3128 cm ^−1, and it was confirmed that the imidazole group was bonded to the sulfonated fullerene.

(Comparative Example 1)
In Example 1, the same operation was performed using dimethylformamide instead of dimethylacetamide, and the infrared absorption spectrum of the product after sulfonation was measured. As a result, many peaks appeared, and the solvent dimethylformamide bound to fullerene. It was confirmed that

(Example 2)
In Example 1, the same operation was performed using 2-mercaptobenzimidazole in place of 2-mercaptoimidazole and dimethylacetamide in place of dioxane as a solvent to obtain a sulfonated fullerene having a benzimidazole group bonded thereto.

(Example 3)
Diethyl phosphite HPO (OEt) ₂ (690 mg) and dioxane (200 ml) were placed in a 300 ml three-necked flask, and LiH (40 mg) was added. When heated and stirred at 80 ° C., H ₂ was generated and eventually the solution became transparent. Thus, 720 mg of fullerene C ₆₀ was added, and the mixture was heated and stirred at 80 ° C. for 4 days.
After completion of the reaction, the solvent was removed by drying, and the residue was extracted with (ethanol + THF). The solid was filtered off, after which the filtrate of the (ethanol + THF) was removed by drying, it was measured infrared absorption spectrum in KBr, _C 2 _H 5 to 2926cm ^-1, to 1209cm ^-1 P = O, 1043cm ^-1 P—O—C absorption was observed, and it was confirmed that the phosphonate ester group PO (OEt) ₂ was bonded.

1 g of trimethylsilyl bromide was added to 500 mg of this phosphonate esterified fullerene and the ester exchange was carried out overnight at room temperature, followed by hydrolysis with water. After drying the obtained product was measured with infrared absorption spectrum in _KBr, absorption of C 2 _{H 5} is lost, OH to 3348cm ^-1, to 1184cm ^-1 P = O, the 1074Cm ^-1 Absorption of PO-C appeared.
The obtained phosphonated fullerene was subjected to P analysis by ICP-AES, and the results of elemental analysis of C, H, O by combustion method were C73.9%, P10.6%, H1.4%, O15. 5%, and it was confirmed that about 3 to 4 phosphonic acid groups PO (OH) ₂ and H were bonded.

Furthermore, when the sample was dissolved in D ₂ O and NMR was measured, a peak presumed to be a proton at the beta position was confirmed. The yield of the phosphonated fullerene obtained was approximately 35% on a fullerene basis.
When the phosphonated fullerene was reacted with 2-mercaptoimidazole in the same manner as in Example 1, a phosphonated fullerene having an imidazole group bonded thereto was obtained. An S analysis of the product revealed that one imidazole group was bonded.

(Comparative Example 2)
In Example 3, the same operation was carried out using dimethylformamide instead of dioxane, and phosphonate esterification reaction was performed. As a result, many peaks appeared in the infrared absorption spectrum of the product, and the solvent dimethylformamide was bound. It was confirmed that

Example 4
In a 300 ml three-necked flask, 80 g of dioxane was added, 0.4 g of 2-mercaptoimidazole and 0.05 g of lithium hydride were added, and the mixture was stirred at 50 ° C. After the generation of hydrogen bubbles ceased, 0.72 g of fullerene C ₆₀ was added and stirred at 80 ° C. for 2 nights. As a result, the reacted fullerene was dissolved in a solvent to form a black brown solution.
After completion of the reaction, dioxane was removed by evaporation with an evaporator, the residue was washed with methanol, and the infrared absorption spectrum was measured. In the obtained IR, absorption specific to the imidazole group was observed at 2500 to 3128 cm ^−1, and it was confirmed that imidazolated fullerene was generated.

In place of the raw material fullerene C ₆₀ of Example 2, the above imidazolated fullerene was used in the same manner as in Example ₂ and reacted with HPO (OEt) _{2. As} a result, imidazolated fullerene having a phosphonated ester group bonded thereto was obtained. was gotten.

(Example 5)
When the same operation as in Example 3 was performed using the sulfonated fullerene obtained in Example 1 as a raw material, absorption of sulfonic acid groups and phosphonic acid ester groups appeared in the infrared absorption spectrum. It was confirmed that When P analysis was performed by ICP-AES, it was estimated that about two phosphonic acid groups were bonded.
Using the obtained (sulfonic acid + phosphonic ester) fullerene as a raw material, the same procedure as in Example 1 was followed to bond the imidazole group to the fullerene.

(Example 6)
When the phosphonated fullerene imidazole group obtained is bound in Example 3, using trifluoroacetic acid as solvent, measuring the infrared absorption spectrum of the product is reacted for 2 nights with hydrogen peroxide and 70 ° C., SO ₂ It was confirmed that the sulfide bond was oxidized to the sulfone bond.

Claims (3)

Cation raw material for ionic liquid having chemical structure (X) _m -Y-fullrene- (Z) _n (where X is an imidazole group or benzimidazole group; Y is S or SO ₂ ; Z is a sulfonic acid group, phosphone) An acid group or a precursor thereof; m is an integer of 1 to 4; n is an integer of 1 to 10; m + n = 2 to 12). It is a manufacturing method of the cation raw material for ionic liquids according to claim 1,
The mercapto group of 2-mercaptoimidazole or 2-mercaptobenzimidazole is changed to SM by MH in dioxane or dimethylacetamide, and reacted with fullerene at normal pressure or under pressure at 20 to 200 ° C. for 10 to 200 hours. A step of bonding an imidazole group to fullerene (where M is Li, Na or K);
In the case of the sulfonating reagent M ₂ SO ₃ (dimethylacetamide + water), in the case of the phosphonating reagent MPO (OR) ₂ , a specific reaction solvent of dioxane is selected, and in the solvent, fullerene and M ₂ SO ₃ or MPO are selected. (OR) ₂ is a step of dispersing a sulfonic acid group, a phosphonic acid group or a precursor thereof to fullerene by dispersing ₂ and reacting at normal pressure or under pressure using a reaction temperature of 20 to 200 ° C. for 10 to 200 hours. (here, M Li, Na or K; R is _C 1 alkyl group or a phenyl group -C ₅₎ the method of producing an ionic liquid for the cation material and a. In the manufacturing method of Claim 2,
Using an oxidizing agent such as hydrogen peroxide, peracetic acid, potassium permanganate, sodium perborate or the like, under normal pressure or under pressure, reaction conditions of 20 to 200 ° C. for 10 to 200 hours are used to treat X-S-fullrene. _X-SO 2 -fullerene further comprising manufacturing method of ionic liquids for cation raw material step of oxidizing the.