JP5703009B2 - Sulfone compound, method for producing sulfone compound, and electrolytic solution for electrochemical device - Google Patents

Description

  The present invention relates to a novel sulfone compound useful mainly as a solvent for electrochemical devices. Moreover, this invention relates to the manufacturing method of this sulfone compound, and the electrolyte solution for electrochemical devices manufactured using this sulfone compound.

  While sulfone compounds are used as extraction solvents and various reaction solvents, those having a high dielectric constant are also used as aprotic polar solvents and as solvents for electrolyte solutions in electrochemical devices. Specifically, an electric double layer capacitor using a sulfolane derivative such as sulfolane or 3-methylsulfolane, which is a sulfone compound, as a solvent for an electrolytic solution (Patent Document 1), a sulfolane derivative such as sulfolane or 3-methylsulfolane, and propylene An electric double layer capacitor (Patent Document 2) using a mixed solvent with carbonate as a solvent for an electrolytic solution has been proposed.

JP-A-62-237715 Japanese Patent Laid-Open No. 63-12122

  Aprotic polar solvents used for solvents for electrochemical devices and the like are generally desired to have a low melting point and excellent thermal stability. Also, depending on the type of electrochemical device, the presence of moisture in the system may be a problem, and in that case, a solvent having low water solubility is preferably used.

  However, since the sulfone compounds described in Patent Document 1 and Patent Document 2 have a relatively high melting point, there are problems such as a decrease in the function of an electrochemical device using them in a low temperature environment. Moreover, the propylene carbonate used together with these has problems such as poor thermal stability and relatively high solubility in water.

Furthermore, the electrolytic solution described in Patent Document 1 and Patent Document 2, and the conventional electrolytic solution using propylene carbonate or γ-butyrolactone as a solvent cannot be said to have a sufficiently high decomposition voltage. In the case of an electrolytic solution having an insufficient decomposition voltage, gas may be generated or a reaction product may be deposited on the electrode when a high voltage exceeding 2.5 V is continuously applied. As a result, there is a problem that an increase in internal resistance and a decrease in capacity occur, and an electrolyte solvent that can withstand use at a higher voltage is desired.
An object of the present invention is to provide a novel sulfone compound useful for an aprotic polar solvent having a relatively low melting point, excellent thermal stability, low water solubility, and high decomposition voltage characteristics. . Another object of the present invention is to provide a method for producing the sulfone compound and an electrolytic solution for electrochemical devices produced using the sulfone compound.

  The present invention relates to a sulfone compound represented by the following formula (1), a method for producing the sulfone compound, and an electrolytic solution for an electrochemical device produced using the sulfone compound.

That is, the present invention
Item 1. A sulfone compound represented by formula (1),
Item 2. Item 2. The sulfone compound according to item 1, wherein in formula (1), R is a methyl group, an ethyl group, an n-propyl group, or an isopropyl group,
Item 3. Item 3. The sulfone compound according to item 1 or 2, which is used for an electrolytic solution of an electrochemical device,
Item 4 . A process for producing a sulfone compound represented by formula (1), wherein a sulfide compound represented by formula (2) is reacted with an oxidizing agent;
Item 5 . An electrolyte for an electrochemical device containing a sulfone compound represented by formula (1),
About.

In the formula (1), R represents an alkyl group having 1 to 3 carbon atoms.

In formula (2), R represents an alkyl group having 1 to 3 carbon atoms. In item 3, R in formula (1) and R in formula (2) represent the same group. The present invention is described in detail below.

  The sulfone compound according to the present invention is a compound represented by the formula (1).

  Examples of the alkyl group having 1 to 6 carbon atoms represented by R include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, and an isopentyl group. Group, cyclopentyl group, n-hexyl group, cyclohexyl group and the like.

  The alkyl group having 1 to 6 carbon atoms represented by R is preferably a chain alkyl group having 1 to 3 carbon atoms, and among these, a methyl group, an ethyl group, an n-propyl group, and an isopropyl group are more preferable.

  Specific examples of the sulfone compound represented by the formula (1) include (2-cyanoethanesulfonyl) acetic acid methyl ester, (2-cyanoethanesulfonyl) acetic acid ethyl ester, and (2-cyanoethanesulfonyl) acetic acid n. -Propyl ester, (2-cyanoethanesulfonyl) acetic acid isopropyl ester, (2-cyanoethanesulfonyl) acetic acid n-butyl ester, (2-cyanoethanesulfonyl) acetic acid isopentyl ester, and (2-cyanoethanesulfonyl) acetic acid cyclohexyl Examples include esters. Among these, (2-cyanoethanesulfonyl) acetic acid methyl ester, (2-cyanoethanesulfonyl) acetic acid ethyl ester, (2-cyanoethanesulfonyl) acetic acid n-propyl ester, and (2-cyanoethanesulfonyl) acetic acid isopropyl ester Is preferably used.

  The sulfone compound represented by the formula (1) can be produced, for example, by the following method. That is, it can be produced by reacting the sulfide compound represented by the formula (2) with an oxidizing agent. A method for producing the sulfone compound represented by the formula (1) in which the sulfide compound represented by the formula (2) is reacted with an oxidizing agent is also one aspect of the present invention.

  The sulfide compound represented by the formula (2) may be obtained by any production method, but can be produced, for example, by the following method. That is, it can be produced by reacting a thioglycolic acid ester represented by the following formula (3) with acrylonitrile.

  In formula (3), R shows a C1-C6 alkyl group.

  A commercially available thioglycolic acid ester represented by the formula (3) can be used.

  Specific examples of the thioglycolic acid ester represented by the formula (3) include thioglycolic acid methyl ester, thioglycolic acid ethyl ester, thioglycolic acid n-propyl ester, thioglycolic acid isopropyl ester, and thioglycolic acid ester. Examples include glycolic acid n-butyl ester.

  In the reaction of the thioglycolic acid ester represented by the formula (3) and acrylonitrile, the use ratio of acrylonitrile is 0.5 to 10 with respect to 1 mol of the thioglycolic acid ester represented by the formula (3). It is preferable that it is mol, and it is more preferable that it is 0.8-2 mol.

  In the reaction of the thioglycolic acid ester represented by the formula (3) with acrylonitrile, a catalyst can be used as necessary. Although it does not specifically limit as said catalyst, A well-known basic catalyst can be used, For example, diethylamine, a triethylamine, etc. are used suitably.

  The use ratio of the catalyst is preferably 1 mol or less, and more preferably 0.05 to 0.2 mol, with respect to 1 mol of the thioglycolic acid ester represented by the formula (3).

  In the reaction between the thioglycolic acid ester represented by the formula (3) and acrylonitrile, no solvent may be used, but the raw material is solid or the reaction solution has a high viscosity and insufficient stirring. In some cases, it may be used as necessary. The solvent to be used is not particularly limited. For example, halogen such as carbon tetrachloride, chloroform, dichloromethane, bromopropane, bromobutane, bromopentane, bromohexane, methyl iodide, ethyl iodide, and propyl iodide. Alkyls, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, petroleum ether, benzine, kerosene, toluene, xylene, mesitylene, And hydrocarbons such as benzene. These solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the usage-amount of the said solvent is not specifically limited, It is preferable that it is 5000 parts weight or less with respect to 100 weight part of thioglycolic acid ester represented by the said Formula (3).

  The preferable lower limit of the reaction temperature of the reaction between the thioglycolic acid ester represented by the formula (3) and acrylonitrile is 0 ° C, the preferable upper limit is 100 ° C, the more preferable lower limit is 10 ° C, and the more preferable upper limit is 50 ° C. is there. The reaction time is usually 1 to 10 hours.

  The sulfide compound represented by the formula (2) thus obtained can be isolated by washing and separating with water or the like, and then concentrating and drying, or by distillation.

  Specific examples of the sulfide compound represented by the formula (2) include, for example, (2-cyanoethanethio) acetic acid methyl ester, (2-cyanoethanethio) acetic acid ethyl ester, (2-cyanoethanethio) acetic acid n-propyl ester, (2 -Cyanoethanethio) acetic acid isopropyl ester, (2-cyanoethanethio) acetic acid n-butyl ester, and the like.

  In the method for producing the sulfone compound according to the present invention, the oxidizing agent used for the oxidation of the sulfide compound represented by the formula (2) is not particularly limited, and specifically, for example, potassium permanganate , Chromic acid, oxygen, hydrogen peroxide solution, and organic oxides such as 3-chloroperbenzoic acid. Among these, 3-chloroperbenzoic acid is preferably used.

  The ratio of the oxidizing agent used is not particularly limited, but the preferable lower limit is 1.8 mol, the preferable upper limit is 10 mol, and the more preferable lower limit is 2 mol with respect to 1 mol of the sulfide compound represented by the formula (2). A more preferred upper limit is 5 moles.

  When oxidizing the sulfide compound represented by the formula (2), a solvent may not be used. However, in the case where the raw material is solid, or the viscosity of the reaction solution is high and stirring is insufficient. You may use as needed. The solvent to be used is not particularly limited. For example, halogen such as carbon tetrachloride, chloroform, dichloromethane, bromopropane, bromobutane, bromopentane, bromohexane, methyl iodide, ethyl iodide, and propyl iodide. Alkyls, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, petroleum ether, benzine, kerosene, toluene, xylene, mesitylene, And hydrocarbons such as benzene, and water. Of these, alkyl halides and water are preferably used. These solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

  Although the usage-amount of the said solvent is not specifically limited, It is preferable that it is 5000 weight part or less with respect to 100 weight part of sulfide compounds shown by the said Formula (2).

  The preferable lower limit of the reaction temperature of the reaction for oxidizing the sulfide compound represented by the formula (2) is 0 ° C., the preferable upper limit is 200 ° C., the more preferable lower limit is 10 ° C., and the more preferable upper limit is 150 ° C. Moreover, the reaction time of the reaction for oxidizing the sulfide compound represented by the formula (2) is usually 1 to 30 hours.

  The sulfone compound represented by the formula (1) thus obtained is isolated by filtering the reaction solution as necessary, washing and separating with water, etc., and then concentrating and drying, or by distillation. be able to.

  The sulfone compound according to the present invention can be suitably used, for example, as a solvent for an electrolytic solution of an electrochemical device. The electrolytic solution for electrochemical devices containing the sulfone compound represented by the formula (1) is also one aspect of the present invention.

  Examples of the electrochemical device include a lithium primary battery, a lithium secondary battery, a lithium ion battery, a fuel cell, a solar cell, and an electric double layer capacitor.

When using the sulfone compound concerning this invention as a solvent for the electrolyte solution of an electrochemical device, this sulfone compound may be used independently and may be used in mixture with another solvent.
Examples of the other solvent include propylene carbonate, butylene carbonate, γ-butyrolactone, 1,3-dioxolane, acetonitrile, propionitrile, butyronitrile, dimethylformamide, 1,2-dimethoxyethane, propylisobutylsulfone, propyl sec- Butylsulfone, propyl t-butylsulfone, isopropylbutylsulfone, isopropylisobutylsulfone, isopropyl sec-butylsulfone, isopropyl t-butylsulfone, butylisobutylsulfone, butylsec-butylsulfone, isobutylt-butylsulfone, sec-butylt- Butyl sulfone, butyl t-butyl sulfone, sec-butyl isobutyl sulfone, propyl isobutyl sulfone, propyl isopentyl sulfone , Isopropyl isopentyl sulfone, propyl isohexyl sulfone, isopropyl isohexyl sulfone, and sulfolane, and the like.

  The ratio of mixing the sulfone compound and the other solvent when using the other solvent is not particularly limited, but the amount of the other solvent used is preferably 4000 parts by weight or less with respect to 100 parts by weight of the sulfone compound. From the standpoint of not being able to obtain an effect commensurate with the amount used, it is more preferably 20 to 2000 parts by weight.

  The electrolyte used in the electrolytic solution for electrochemical devices according to the present invention is not particularly limited. For example, hexafluorophosphate, tetrafluoroborate, perchlorate, and trichlorate of alkali metals such as lithium Fluoroalkyl sulfonates and hexafluorophosphates such as tetraalkylammonium, tetrafluoroborate, perchlorate, and trifluoroalkyl sulfonates.

  Examples of the tetraalkylammonium include triethylmethylammonium, tetraethylammonium, tetrabutylammonium, diethyldimethylammonium, ethyltrimethylammonium, dimethylpyrrolidinium, diethylpyrrolidinium, ethylmethylpyrrolidinium, spiro- (1,1 ) -Pyrrolidinium, N-methyl-N-spiropyrrolidinium, diethylpiperidinium, spiro- (1,1) -piperidinium, and the like. Among these, tetraalkylammonium hexafluorophosphate and tetrafluoroborate are preferable from the viewpoints of solubility in solvents and electrochemical stability. These electrolytes may be used individually by 1 type, and may be used in combination of 2 or more type.

The concentration of the electrolyte in the electrolytic solution for electrochemical devices according to the present invention is not particularly limited, but is preferably 0.1 to 1.0 mol / L because sufficient electrical conductivity is obtained. More preferably, it is 6-0.7 mol / L.
The electrolyte solution according to the present invention may contain various additives such as a stabilizer for the purpose of improving electrochemical performance and the like.

  The water content of the electrolytic solution for electrochemical devices according to the present invention is preferably 30 ppm or less. When the water content exceeds 30 ppm, the performance of the electrochemical device may be adversely affected.

  The atmosphere for preparing the electrolytic solution for an electrochemical device according to the present invention is preferably prepared in an environment in which air is not mixed, for example, in a glove box having an inert atmosphere such as argon gas and nitrogen gas. The moisture in the work environment can be managed with a dew point meter. Since water in the electrolytic solution adversely affects the performance of the electrochemical device, it is preferable to prepare the electrolytic solution for an electrochemical device according to the present invention in a low dew point atmosphere. Specifically, the preparation is preferably performed in an atmosphere having a dew point of −15 ° C. or less, and the preparation is performed in an atmosphere having a dew point of −50 ° C. to −80 ° C. (water content is about 39 ppm to about 0.5 ppm). It is more preferable to carry out. When the dew point exceeds −15 ° C. and the working time becomes long, the electrolyte solution absorbs moisture in the atmosphere, and thus the moisture in the electrolyte solution may increase. The temperature at the time of preparing the electrolytic solution for an electrochemical device according to the present invention may be room temperature.

  Since the sulfone compound according to the present invention has a relatively low melting point and excellent thermal stability, it can be used in a wide temperature range from a low temperature to a high temperature. In addition, since the sulfone compound according to the present invention has the characteristics of low water solubility and high decomposition voltage, when used in an electrolytic solution of an electrochemical device, water mixing can be suppressed, and current efficiency can be reduced. Problems such as a decrease and an increase in internal pressure can be prevented, and a higher voltage can be withstood.

6 is a graph showing the results of linear sweep voltammetry of the electrolyte solutions obtained in Example 3, Comparative Example 3, and Comparative Example 4.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Example 1
[Production of (2-cyanoethanesulfonyl) acetic acid methyl ester (CEAMH)]
In a 500 mL four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser, under a nitrogen atmosphere, 246.7 g (2.32 mol) of thioglycolic acid methyl ester and 8.50 g of diethylamine (0.12) Mol) was added, and 123.3 g (2.32 mol) of acrylonitrile was gradually added, followed by stirring at 30 ° C. for 2 hours.
Then, 100.0 g of ultrapure water was added, and the organic layer was separated and distilled to obtain 255.6 g of (2-cyanoethanethio) acetic acid methyl ester in which R in the formula (2) is a methyl group. The yield of the obtained (2-cyanoethanethio) acetic acid methyl ester was 69% based on thioglycolic acid methyl ester.

The obtained (2-cyanoethanethio) acetic acid methyl ester could be identified from the following physical properties.
¹ H-NMR (400 MHz, solvent: CDCl ₃ ): 2.75 (t, J = 7.2 Hz, 2H), 2.80 (t, J = 7.2 Hz, 2H), 3.40 (s, 2H ), 3.80 (s, 3H)

Next, 178.7 g (1.12 mol) of the obtained (2-cyanoethanethio) acetic acid methyl ester and 1116.5 g of dichloromethane were added to a 3 L four-neck equipped with a stirrer, thermometer, dropping funnel and condenser. The flask was charged. Furthermore, after gradually adding 503.0 g of 77% by weight of 3-chloroperbenzoic acid (2.24 mol as a pure component) under a nitrogen atmosphere, the mixture was maintained at 50 ° C. and stirred for 20 hours. After cooling this to room temperature, the reaction solution is filtered to remove remaining 3-chloroperbenzoic acid and the like, and the filtrate is washed once with 55 g of a 5 wt% aqueous sodium sulfite solution, and further 5 wt% aqueous sodium carbonate solution. Washed twice with 55 g.
By concentrating and drying the obtained filtrate, 156.0 g of (2-cyanoethanesulfonyl) acetic acid methyl ester in which R in the formula (1) is a methyl group was obtained. The yield of the obtained (2-cyanoethanesulfonyl) acetic acid methyl ester was 73% with respect to (2-cyanoethanethio) acetic acid methyl ester.

The obtained (2-cyanoethanesulfonyl) acetic acid methyl ester could be identified from the following physical properties.
¹ H-NMR (400 MHz, solvent: CDCl ₃ ): 2.97 (t, J = 7.2 Hz, 2H), 3.66 (t, J = 7.2 Hz, 2H), 3.86 (s, 3H ), 4.13 (s, 2H)

(Example 2)
[Production of (2-cyanoethanesulfonyl) acetic acid ethyl ester (CEAEH)]
In a 500 mL four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser, under a nitrogen atmosphere, 180.3 g (1.50 mol) of ethyl thioglycolate and 5.49 g (0.075 mol) of diethylamine were added. In addition, 79.6 g (1.50 mol) of acrylonitrile was gradually added, followed by stirring at 30 ° C. for 2 hours.
Thereafter, 60.0 g of ultrapure water was added, and the organic layer was separated and distilled to obtain 181.9 g of (2-cyanoethanethio) acetic acid ethyl ester in which R in the formula (2) is an ethyl group. The yield of the obtained (2-cyanoethanethio) acetic acid ethyl ester was 70% based on thioglycolic acid ethyl ester.

The obtained (2-cyanoethanethio) acetic acid ethyl ester could be identified from the following physical properties.
¹ H-NMR (400 MHz, solvent: CDCl ₃ ): 1.34 (t, J = 6.8 Hz, 3H), 2.80 (t, J = 7.2 Hz, 2H), 2.83 (t, J = 7.2 Hz, 2H), 3.45 (s, 2H), 4.22 (t, J = 6.8 Hz, 2H)

Next, 173.2 g (1.00 mol) of the obtained (2-cyanoethanethio) acetic acid ethyl ester and 1000.7 g of dichloromethane were added to a 3 L four-neck equipped with a stirrer, a thermometer, a dropping funnel and a condenser. The flask was charged. Further, under a nitrogen atmosphere, 448.2 g (2.00 mol as a pure component) of 77% by weight of 3-chloroperbenzoic acid was gradually added, and the mixture was maintained at 50 ° C. and stirred for 20 hours. After cooling this to room temperature, the reaction solution is filtered to remove remaining 3-chloroperbenzoic acid and the like, and the filtrate is washed once with 50 g of a 5 wt% aqueous sodium sulfite solution, and further 5 wt% aqueous sodium carbonate solution. Washed twice with 50 g.
By concentrating and drying the obtained filtrate, 90.3 g of (2-cyanoethanesulfonyl) acetic acid ethyl ester in which R in the formula (1) is an ethyl group was obtained. The yield of the obtained (2-cyanoethanesulfonyl) acetic acid ethyl ester was 44% with respect to (2-cyanoethanethio) acetic acid ethyl ester.

The obtained (2-cyanoethanesulfonyl) acetic acid ethyl ester could be identified from the following physical properties.
¹ H-NMR (400 MHz, solvent: CDCl ₃ ): 1.30 (t, J = 6.8 Hz, 3H), 2.95 (t, J = 7.2 Hz, 2H), 3.82 (t, J = 7.2 Hz, 2H), 4.05 (t, J = 6.8 Hz, 2H), 4.12 (s, 2H)

About the sulfone compound obtained in Example 1 and Example 2, melting | fusing point and exothermic starting temperature were measured using the differential scanning calorimeter in nitrogen atmosphere. Moreover, the solubility of water was measured by measuring the water | moisture content of the said sulfone compound which dissolved water saturated using the Karl Fischer coulometric titration apparatus.
The respective measurement results are shown in Table 1 together with propylene carbonate as Comparative Example 1 and sulfolane as Comparative Example 2.

  From the results of Table 1, the sulfone compounds obtained in Example 1 and Example 2 have a lower melting point than Comparative Example 2, and excellent thermal stability compared to Comparative Example 1 and Comparative Example 2, It can also be seen that the solubility of water is low.

(Example 3)
[Preparation of electrolyte solution containing (2-cyanoethanesulfonyl) acetic acid methyl ester (CEAMH)]
In a dry box having a dew point of less than −50 ° C., 1.07 g (0.00325 mol) of tetrabutylammonium tetrafluoroborate was charged into a 5 mL volumetric flask and obtained in Example 1 (2-cyanoethanesulfonyl). ) Acetic acid methyl ester (CEAMH) was diluted to 5 mL to prepare an electrolytic solution having an electrolyte concentration of 0.65 mol / L. The water content of the prepared electrolyte was 20 ppm.

(Comparative Example 3)
An electrolytic solution was prepared in the same manner as in Example 3 except that sulfolane was used instead of CEAMH.

(Comparative Example 4)
In Example 3, an electrolytic solution was prepared in the same manner as in Example 3 except that propylene carbonate was used instead of CEAMH.

A potentiogalvanostat (manufactured by BAS) is used as a measuring device, a glassy carbon electrode having an electrode outer diameter of 6 mm and an electrode size of 1.6 mm as a working electrode, and a platinum electrode having a length of 5 cm and a platinum diameter of 0.5 mm as a counter electrode. Using. In addition, as the solvent system reference electrode, the electrolyte solution prepared in a cell equipped with an internal solution acetonitrile / tetrabutylammonium perchlorate silver / silver ion electrode was charged, and linear sweep voltammetry was performed at a potential scanning speed of 5 mV / s. The decomposition potential was measured by (LSV).
The results of linear sweep voltammetry of the electrolyte solution containing CEAMH obtained in Example 3 are shown in FIG. 1 together with the measurement results of the electrolyte solutions obtained in Comparative Example 3 and Comparative Example 4.

  1 that the electrolytic solution of Example 3 has a higher decomposition voltage than the electrolytic solutions of Comparative Example 3 and Comparative Example 4. Therefore, it can be seen that the electrolytic solution containing CEAMH obtained in Example 3 can be used at a higher voltage.

  The present invention can provide a novel sulfone compound useful for an aprotic polar solvent having a relatively low melting point, excellent thermal stability, low water solubility, and high decomposition voltage characteristics. . Moreover, according to this invention, the manufacturing method of this sulfone compound and the electrolyte solution for electrochemical devices manufactured using this sulfone compound can be provided.

Claims (5)

The sulfone compound represented by Formula (1).

In the formula (1), R represents an alkyl group having 1 to 3 carbon atoms.   The sulfone compound according to claim 1, wherein in the formula (1), R is a methyl group, an ethyl group, an n-propyl group, or an isopropyl group.   The sulfone compound according to claim 1 or 2, which is used for an electrolytic solution of an electrochemical device. The manufacturing method of the sulfone compound represented by Formula (1) with which the sulfide compound represented by Formula (2) and an oxidizing agent are made to react.

In formula (2), R represents an alkyl group having 1 to 3 carbon atoms.

In formula (1), R represents the same group as R in formula (2). Electrolyte solution for electrochemical devices containing a sulfone compound represented by formula (1).

In the formula (1), R represents an alkyl group having 1 to 3 carbon atoms.

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