JP2014185094A - Production method of carboxy sulfonium salt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensive and high-yield production of a carboxy sulfonium salt having excellent solubility to an aprotic solvent and being suitable for an electrolyte of an electrolytic solution for an electrochemical device.SOLUTION: A production method of a carboxy sulfonium salt represented by the formula (5) has a step 1 where a thiol or sulfide compound having an alkyl group with a carbon number of 1 to 5 and a halogenated alkyl compound having an alkyl group with a carbon number of 1 to 5 are reacted to obtain a halogenated sulfonium salt and a step 2 where the halogenated sulfonium salt obtained in the step 1 is reacted with a silver oxide and a specific carboxylic acid. In the formula (5), Rand Rrepresent a hydrogen atom or an alkyl group with a carbon number of 1 to 5, Rrepresents an alkyl group with a carbon number of 1 to 5, and Rrepresents a hydrogen atom, an alkyl group with a carbon number of 1 to 5, or an aromatic group in which a hydrogen at α-position of an aromatic ring with a carbon number of 6 to 16 is substituted by a carboxy group.

Description

The present invention relates to a method for producing a carboxysulfonium salt used as an electrolyte of an electrochemical device such as an electrolytic capacitor.

Electrochemicals such as various secondary batteries and aluminum electrolytic capacitors that can obtain high energy density as devices used for power supplies for electronic equipment, power storage power supplies, power supplies for automobiles, etc. Devices are drawing attention.

As an electrolytic solution used in an electrochemical device, in order to improve the output density and energy density of the electrochemical device, an organic organic electrolytic solution is more frequently used than an aqueous electrolytic solution from the viewpoint of voltage resistance.
Electrolytic solutions used in electrochemical devices such as electrolytic capacitors are required to have high conductivity because the internal resistance increases when the electrical conductivity is low, and voltage drops during charging and discharging. . However, organic electrolytes are inferior in electrical conductivity to aqueous electrolytes, and many studies on organic solvents and electrolytes have been conducted in order to improve electrical conductivity.
For example, Patent Documents 1 and 2 disclose an electrolytic solution in which a quaternary ammonium salt, a quaternary phosphonium salt, or the like is dissolved in an aprotic solvent such as γ-butyrolactone or propylene carbonate.

An electrolyte for driving an electrochemical device such as an electrolytic capacitor is required to have low temperature dependency in order to enable use in a wider temperature range. That is, it is required to maintain excellent conductivity even at low temperatures. The conductivity is proportional to the electrolyte concentration in the electrolyte solution, that is, the ion concentration. For this reason, the one where the electrolyte concentration in electrolyte solution is higher is preferable.
However, when the electrolyte concentration in the electrolytic solution is increased, the electrolyte in the electrolytic solution is likely to be deposited at a low temperature. Therefore, in order to prevent the electrolyte at low temperature from precipitating, it is necessary to increase the solubility of the electrolyte in the electrolytic solution.

As an electrolytic solution having high conductivity at a low temperature, an electrolytic solution using a tertiary sulfonium salt excellent in solubility in an aprotic solvent as an electrolyte has been reported. As a method for producing a tertiary sulfonium salt, Patent Document 3 discloses that a halogenated sulfonium salt is produced by allowing an alkyl halide to act on a secondary sulfide. A method of performing anion exchange by reacting lithium bis (trifluoromethanesulfonyl) imide or the like is disclosed. However, the electrolyte obtained by the method disclosed in Patent Document 3 may generate a strong acid such as trifluoromethanesulfonic acid as a free acid. Such a free acid is likely to affect battery performance because it degrades the electrode and the like.

Patent Document 4 discloses a method for obtaining a carboxysulfonium salt by adding 1 equivalent of silver carboxylate to a halogenated sulfonium salt. When such a carboxysulfonium salt is used as an electrolyte, there is little influence of a free acid such as an electrolyte obtained by the method disclosed in Patent Document 3. However, in the method disclosed in Patent Document 4, it is necessary to use an equivalent amount of silver carboxylate, which is not economical and difficult to industrialize. In particular, silver carboxylate having a large number of carbon atoms has a problem that it is not readily available because it is expensive and is not suitable for industrial production.

Japanese Patent Laid-Open No. Sho 63-17312 JP 63-1014 A JP 2009-249313 A International Publication No. 11/083872 Pamphlet

An object of the present invention is to provide a method for producing a carboxysulfonium salt excellent in solubility in an aprotic solvent and suitable for an electrolyte of an electrolytic solution for an electrochemical device at a low cost and in a high yield.

The present invention is a step 1 for obtaining a halogenated sulfonium salt represented by the following formula (3) by reacting a compound represented by the following formula (1) with a halogenated alkyl compound represented by the following formula (2). And the halogenated sulfonium salt obtained in the step 1 is reacted with silver oxide and a carboxylic acid represented by the following formula (4), and the carboxysulfonium salt represented by the following formula (5). It is a manufacturing method.

In formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and may be the same or different from each other.

In formula (2), R ³ represents an alkyl group having 1 to 5 carbon atoms, and X represents a halogen atom.

In the formula (3), ^{R 1} and ^{R 2} each represent the same atom or group as ^{R 1} and ^{R 2} in formula (1), ^{R 3} represents the same atom or group as ^{R 3} in Formula (2) .

In formula (4), R ⁴ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aromatic group in which the hydrogen at the α-position of the aromatic ring having 6 to 16 carbon atoms is substituted with a carboxy group. .

In formula (5), ^{R 1} and ^{R 2} each represent the same atom or group as ^{R 1} and ^{R 2} in formula (1), ^{R 3} represents the same atom or group as ^{R 3} in Formula (2) , R ⁴ represents the same atom or group as R ⁴ in formula (4).

Hereinafter, the present invention will be described in detail.
The present inventors have made a halogenated sulfonium salt obtained by reacting a dialkyl sulfide compound and the like with a halogenated alkyl compound in combination with silver oxide and a specific carboxylic acid, thereby reacting with an aprotic solvent. The present inventors have found that a carboxysulfonium salt that is excellent in solubility and suitable for an electrolyte of an electrolytic solution for electrochemical devices can be produced at low cost and in high yield, and the present invention has been completed.
Unlike the carboxylic acid silver used in the method disclosed in Patent Document 4, the carboxylic acid used in the method for producing a carboxysulfonium salt of the present invention can be obtained at a low cost even when the number of carbons increases.
Moreover, in the method disclosed in Patent Document 4, the reaction is allowed to proceed in a mixed solvent of water and acetonitrile to produce a carboxysulfonium salt, so that the resulting carboxysulfonium salt is likely to contain water. If a carboxysulfonium salt containing water is used in an electrolyte for an electrochemical device, the electrochemical device may be deteriorated, and thus water must be sufficiently removed. On the other hand, in the method for producing a carboxysulfonium salt of the present invention, such a problem does not occur because the reaction can proceed in an organic solvent.
Furthermore, in the method for producing a carboxysulfonium salt of the present invention, the reaction proceeds quantitatively, and byproducts such as silver halide can be easily removed.

The method for producing a carboxysulfonium salt of the present invention comprises reacting a compound represented by the above formula (1) with a halogenated alkyl compound represented by the above formula (2) to react the halogen represented by the above formula (3). Step 1 to obtain a sulfonium fluoride salt.

Examples of the compound represented by the formula (1) include dialkyl sulfide compounds, alkyl thiol compounds, and hydrogen sulfide.
In the step 1, when the compound represented by the formula (1) is not used, an aromatic sulfide such as diphenyl sulfide or a dialkyl sulfide compound having a bulky substituent having 6 or more carbon atoms is used. In 2, the anion exchange reaction is inhibited, and the yield of the resulting carboxysulfonium salt decreases.

Examples of the dialkyl sulfide compound represented by the formula (1) include dimethyl sulfide, diethyl sulfide, dipropyl sulfide, dibutyl sulfide, dipentyl sulfide, ethyl methyl sulfide, ethyl propyl sulfide, ethyl isopropyl sulfide, ethyl butyl sulfide, ethyl Examples thereof include isobutyl sulfide, isopropyl sec-butyl sulfide, ethyl pentyl sulfide, ethyl isopentyl sulfide, butyl pentyl sulfide, isobutyl isopentyl sulfide and the like. Of these, dimethyl sulfide and ethyl methyl sulfide are preferred because the molecular weight is low and the resulting carboxysulfonium salt is excellent in solubility in an aprotic solvent.
Examples of the alkyl thiol compound represented by the formula (1) include methyl thiol, ethyl thiol, n-propyl thiol, isopropyl thiol, n-butyl thiol, isobutyl thiol, sec-butyl thiol, tert-butyl thiol. , Pentylthiol, isopentylthiol and the like. Among these, dimethylthiol and ethylthiol are preferable because the molecular weight is low and the resulting carboxysulfonium salt is excellent in solubility in an aprotic solvent.
The compound represented by the formula (1) may be used alone or in combination of two or more.

Examples of the halogenated alkyl compound represented by the formula (2) include methane iodide, ethane iodide, propane iodide, butane iodide, pentane iodide, 2-butane iodide, isopropane iodide, iodine Isopentane, methane bromide, ethane bromide, propane bromide, butane bromide, pentane bromide, 2-butane bromide, isopropane bromide, isopentane bromide, methane chloride, ethane chloride, propane chloride, butane chloride, Examples include pentane chloride, 2-butane chloride, isopropane chloride, and isopentane chloride. Especially, since the obtained carboxysulfonium salt becomes excellent in the solubility to an aprotic solvent, iodomethane and ethane iodide are preferable. These halogenated alkyl compounds may be used alone or in combination of two or more.

In the step 1, the amount of the halogenated alkyl compound represented by the formula (2) is preferably 1.05 mol, and preferably the upper limit is 1 mol of the compound represented by the formula (1). 1.5 moles. When the amount of the halogenated alkyl compound represented by the formula (2) is less than 1.05 mol, the yield of the halogenated sulfonium salt represented by the formula (3) may be lowered. When the amount of the halogenated alkyl compound represented by the formula (2) exceeds 1.5 mol, there is no further effect and it is not economical. The upper limit with the more preferable usage-amount of the halogenated alkyl compound represented by said Formula (2) is 1.2.

In the step 1, as a method of reacting the compound represented by the formula (1) with the halogenated alkyl compound represented by the formula (2), for example, first, it is represented by the formula (1). Examples thereof include a method of dissolving the compound in a polar solvent and adding the halogenated alkyl compound represented by the formula (2). When the compound represented by the formula (1) and the alkyl halide compound represented by the formula (2) are mixed, the halogen represented by the formula (2) is used from the viewpoint of safety. It is preferable to use a method in which the alkyl halide compound is dropped little by little. When the halogenated alkyl compound represented by the formula (2) is added all at once, the temperature of the reaction solution may increase rapidly.
The temperature at the time of dropping the halogenated alkyl compound represented by the formula (2) is preferably 0 to 20 ° C., and since the heat generation can be suppressed by slowly dropping, the dropping time is 0. 0.5 to 3 hours is preferable.

Examples of the polar solvent for dissolving the compound represented by the formula (1) include methanol, ethanol, acetonitrile, diethyl ether, acetone and the like. Among these, acetonitrile is preferable because the compound represented by the formula (1) has high solubility and is excellent in operability because it is difficult to volatilize.

The manufacturing method of the carboxysulfonium salt of this invention has the process 2 which makes the halogenated sulfonium salt obtained at the said process 1 react with the carboxylic acid represented by silver oxide and said Formula (4). Silver oxide and the carboxylic acid represented by the formula (4) can be obtained at a lower cost than silver acetate used in the method disclosed in Patent Document 4. Moreover, the said process 2 can obtain the carboxysulfonium salt represented by the said Formula (5) in a high yield.

In the step 2, the silver oxide is preferably used in an amount of 1.0 mol and a preferable upper limit of 1.5 mol with respect to 1 mol of the halogenated sulfonium salt. When the amount of the silver oxide used is less than 1.0 mol, an unreacted halogenated sulfonium salt may be contained in the product. If the amount of silver oxide used exceeds 1.5 mol, there is no further effect and it is not economical. The upper limit with the more preferable usage-amount of the said silver oxide is 1.1.

Examples of the carboxylic acid represented by the formula (4) include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, orthophthalic acid, isophthalic acid, terephthalic acid, and the like. Of these, acetic acid and propionic acid are preferred because the resulting carboxysulfonium salt has excellent solubility in an aprotic solvent.

In the step 2, the amount of the carboxylic acid represented by the formula (4) used is preferably 1.0 mol and a preferable upper limit is 1.5 mol with respect to 1 mol of the halogenated sulfonium salt. When the amount of the carboxylic acid represented by the formula (4) is less than 1.0 mol, the yield of the carboxysulfonium salt represented by the formula (5) may be lowered. When the usage-amount of carboxylic acid represented by the said Formula (4) exceeds 1.5 mol, when obtaining the carboxysulfonium salt represented by the said Formula (5), drying time may become long. The upper limit with the more preferable usage-amount of the carboxylic acid represented by said Formula (4) is 1.1.

In the step 2, as a method of reacting the halogenated sulfonium salt represented by the formula (3), the silver oxide and the carboxylic acid represented by the formula (4), for example, the formula (3) Step 2-1 for reacting the halogenated sulfonium salt represented by formula (II) with the silver oxide, and Step 2 for reacting the carboxylic acid represented by the formula (4) with the reaction solution obtained in step 2-1. -2 and the like. Specifically, for example, first, the halogenated sulfonium salt represented by the formula (3) is dissolved in a polar solvent, reacted with the silver oxide, and then unreacted silver oxide and silver halide are filtered. The method of removing and adding the carboxylic acid represented by said Formula (4) to a reaction liquid etc. are mentioned. After completion of the reaction, the solvent is distilled off to easily obtain the carboxysulfonium salt compound represented by the formula (5).

As the polar solvent for dissolving the compound represented by the formula (3), the same polar solvent as that for dissolving the compound represented by the formula (1) can be used.

The reaction temperature in Step 2 is preferably 10 to 60 ° C., and the reaction time is preferably 0.5 to 5 hours.

ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing the carboxysulfonium salt excellent in the solubility to an aprotic solvent and suitable for the electrolyte of the electrolyte solution for electrochemical devices with a high yield can be provided.

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

Example 1
(Synthesis of carboxysulfonium salt (1a))
7.6 g (0.1 mol) of ethyl methyl sulfide and 20 g of acetonitrile were stirred in a flask, and 14.9 g (0.105 mol) of iodomethane was added. The resulting mixture was stirred at 25 ° C. under reflux and reacted for 2 hours. After the reaction, the precipitated crystals were separated by filtration, washed with 100 mL of diethyl ether, and then vacuum-dried at 70 ° C. for 3 hours to obtain 21.3 g of ethyldimethylsulfonium iodide salt crystals. 4.4 g (0.02 mol) of the obtained crystal was dissolved in 100 mL of methanol, 4.91 g (0.021 mol) of silver oxide was added, and the mixture was stirred at 25 ° C. for 12 hours. The deposited precipitate was separated by filtration, and 1.2 g (0.02 mol) of acetic acid was added to the filtrate, followed by stirring for 1 hour. The reaction solution was vacuum-dried at 70 ° C. for 5 hours to obtain 3.00 g (0.02 mol) of a carboxysulfonium salt (1a) represented by the following formula (6) (yield 98.2%).
In addition, the obtained carboxysulfonium salt (1a) was identified from having the following physical properties.
¹ H-NMR (400 MHz, solvent: DMSO): 3.41 (q, J = 1.6 Hz, J = 14.8 Hz, J = 7.6 Hz, 2H), 2.96 (s, 6H), 1. 63 (s, 3H), 1.22 (t, J = 7.6 Hz, 3H)

(Example 2)
(Synthesis of carboxysulfonium salt (1b))
A carboxysulfonium salt represented by the following formula (7) in the same manner as in Example 1 except that 1.5 g (0.02 mol) of propionic acid was used instead of 1.2 g (0.02 mol) of acetic acid. 1b) was obtained (yield 97.8%).

(Example 3)
(Synthesis of carboxysulfonium salt (1c))
A carboxysulfonium salt represented by the following formula (8) in the same manner as in Example 1 except that 3.3 g (0.02 mol) of phthalic acid was used instead of 1.2 g (0.02 mol) of acetic acid. 1c) was obtained (yield 98.9%).
In addition, the obtained carboxysulfonium salt (1c) was identified from having the following physical properties.
¹ H-NMR (400 MHz, solvent: DMSO): 8.16 (d, J = 3.6 Hz, J = 2.4 Hz, 2H), 7.51 (d, J = 3.6 Hz, J = 2.4 Hz) , 2H), 3.29 (q, J = 7.6 Hz, J = 7.2 Hz, J = 7.6 Hz, 2H) 2.86 (s, 6H), 1.32 (t, J = 7.6 Hz). , 3H)

Example 4
(Synthesis of carboxysulfonium salt (1d))
A carboxy represented by the following formula (9) was obtained in the same manner as in Example 1 except that 10.4 g (0.02 mol) of ethylpropyl sulfide was used instead of 7.6 g (0.1 mol) of ethyl methyl sulfide. The sulfonium salt (1d) was obtained (yield 99.1%).

(Comparative Example 1)
(Synthesis of carboxysulfonium salt (2a))
In place of ethyl methyl sulfide, 18.6 g (0.1 mol) of diphenyl sulfide was used, 4.29 g (0.021 mol) of iodobenzene was used in place of iodomethane, and 1.2 g (0.02 mol) of acetic acid was used. Instead, a carboxysulfonium salt (2a) represented by the following formula (10) was obtained in the same manner as in Example 1 except that 2.44 g (0.02 mol) of benzoic acid was used (yield 20%). ).

(Comparative Example 2)
(Synthesis of carboxysulfonium salt (1a))
Mixing 4.4 g (0.02 mol) of crystals of ethyldimethylsulfonium iodide obtained in the same manner as in Example 1, 3.34 g (0.02 mol) of silver acetate, 60 mL of acetonitrile, and 30 mL of water. And stirred at room temperature for 1 hour. The obtained reaction solution was filtered, and the filtrate was vacuum-dried at 70 ° C. for 5 hours to obtain a carboxysulfonium salt (1a) (yield 24%).

(Comparative Example 3)
(Synthesis of carboxysulfonium salt (1b))
4.4 g (0.02 mol) of crystals of ethyldimethylsulfonium iodide salt obtained in the same manner as in Example 1, 3.62 g (0.02 mol) of silver propionate, 60 mL of acetonitrile, and 30 mL of water Mix and stir at room temperature for 1 hour. The obtained reaction solution was filtered, and the filtrate was vacuum-dried at 70 ° C. for 5 hours to obtain a carboxysulfonium salt (1b) (yield 28%).

When Examples 1-4 are compared with Comparative Example 1, Examples 1-4 using the compound represented by Formula (3) and the compound represented by Formula (4) are compared with Comparative Example 1. It can be seen that a carboxysulfonium salt can be produced at a high yield in comparison.
Further, when Example 1 and Comparative Example 2 are compared, and Example 2 and Comparative Example 3 are compared, Example 1 and Example 2 using inexpensive silver oxide and acetic acid or propionic acid are expensive silver acetate or silver propionate. It can be seen that the same carboxysulfonium salt can be produced in a higher yield than Comparative Example 2 and Comparative Example 3 in which

ADVANTAGE OF THE INVENTION According to this invention, the method of manufacturing the carboxysulfonium salt excellent in the solubility to an aprotic solvent and suitable for the electrolyte of the electrolyte solution for electrochemical devices with a high yield can be provided.

Claims (1)

A step 1 in which a compound represented by the following formula (1) and a halogenated alkyl compound represented by the following formula (2) are reacted to obtain a halogenated sulfonium salt represented by the following formula (3);
Carboxysulfonium represented by the following formula (5), which comprises the step 2 of reacting the halogenated sulfonium salt obtained in the step 1 with silver oxide and a carboxylic acid represented by the following formula (4) Method for producing salt.

In formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and may be the same or different from each other.

In formula (2), R ³ represents an alkyl group having 1 to 5 carbon atoms, and X represents a halogen atom.

In the formula (3), ^{R 1} and ^{R 2} each represent the same atom or group as ^{R 1} and ^{R 2} in formula (1), ^{R 3} represents the same atom or group as ^{R 3} in Formula (2) .

In formula (4), R ⁴ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an aromatic group in which the hydrogen at the α-position of the aromatic ring having 6 to 16 carbon atoms is substituted with a carboxy group. .

In formula (5), ^{R 1} and ^{R 2} each represent the same atom or group as ^{R 1} and ^{R 2} in formula (1), ^{R 3} represents the same atom or group as ^{R 3} in Formula (2) , R ⁴ represents the same atom or group as R ⁴ in formula (4).