JP5645557B2 - Sulfone compound - Google Patents

Description

  The present invention relates to a sulfone compound. More specifically, the present invention relates to a sulfone compound that is mainly useful as a solvent for electrochemical devices.

  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 electrochemical devices. Specifically, an electric double layer capacitor using a sulfolane derivative such as sulfolane or 3-methylsulfolane as an electrolyte solution (Patent Document 1), a mixture of a sulfolane derivative such as sulfolane or 3-methylsulfolane and propylene carbonate An electric double layer capacitor (Patent Document 2) using a solvent as 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. In addition, according to the type of electrochemical device, the presence of moisture in the system may be a problem, and in this 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.
An object of the present invention is to provide an aprotic polar solvent having a relatively low melting point and excellent thermal stability.

  The present invention relates to a sulfone compound represented by the following formula (1).

  Item 1. Formula (1):

In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 3 carbon atoms.

Item 2. Item 2. The sulfone compound according to Item 1, wherein in Formula (1), R ¹ is a methyl group, and R ² is a group selected from a propyl group or an isopropyl group.

Item 3. Item 2. The sulfone compound according to item 1, wherein R ¹ is an ethyl group and R ² is an isopropyl group in the formula (1).

Item 4. Item 2. The sulfone compound according to Item 1, wherein in Formula (1), R ¹ is a propyl group, and R ² is a group selected from a methyl group, an ethyl group, a propyl group, or an isopropyl group.

Item 5. Item 2. The sulfone compound according to Item 1, wherein in the formula (1), R ¹ is an isopropyl group, and R ² is a group selected from an ethyl group, a propyl group, or an isopropyl group.

  The sulfone compound according to the present invention is an aprotic polar solvent having a relatively low melting point, excellent thermal stability, low water solubility, and low viscosity. It is useful as a solvent for chemical devices.

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

In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 3 carbon atoms.

Examples of the alkyl group having 1 to 3 carbon atoms represented by R ¹ and R ² include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

In the alkyl group having 1 to 3 carbon atoms represented by R ¹ and R ² , a chain alkyl group having 1 to 3 carbon atoms is preferable, and among these, a methyl group, an ethyl group, a propyl group, and an isopropyl group are more preferable. .

Moreover, since the solubility of water will become high too much if the total carbon number is 5 or less, the sulfone compound represented by Formula (1) has a combination of R ¹ and R ^{2 in which} the total carbon number is 6 or more. Preferably used.

  Specific examples of the sulfone compound represented by the formula (1) include, for example, (methoxyethyl) methylsulfone, (ethoxyethyl) methylsulfone, (propoxyethyl) methylsulfone, (isopropoxyethyl) methylsulfone, (methoxyethyl) ) Ethylsulfone, (ethoxyethyl) ethylsulfone, (propoxyethyl) ethylsulfone, (isopropoxyethyl) ethylsulfone, (methoxyethyl) propylsulfone, (ethoxyethyl) propylsulfone, (propoxyethyl) propylsulfone, (methoxyethyl) ) Isopropyl sulfone, (ethoxyethyl) isopropyl sulfone, (propoxyethyl) isopropyl sulfone and the like. Among these, (propoxyethyl) methylsulfone, (isopropoxyethyl) methylsulfone, (isopropoxyethyl) ethylsulfone, (methoxyethyl) propylsulfone, (ethoxyethyl) propylsulfone, (propoxyethyl) propylsulfone, (iso Propoxyethyl) propylsulfone, (ethoxyethyl) isopropylsulfone, (propoxyethyl) isopropylsulfone, and (isopropoxyethyl) isopropylsulfone are preferably used.

The sulfone compound represented by the formula (1) can be produced, for example, by the following method. That is, by reacting an alkoxyethanol represented by formula (2) with a halogenating agent, an organic halogen compound represented by formula (3) is obtained, and this is a sodium salt of thiol represented by formula (4). To obtain a sulfide compound represented by the formula (5). Furthermore, it can be produced by oxidizing it with an oxidizing agent.
Formula (2):

（式中、Ｒ^２は式（１）におけるＲ^２と同じ基を示す。）

(Wherein, ^{R 2} represents the same group as ^{R 2} in the formula (1).)

（式中、Ｘはハロゲン原子を示し、Ｒ^２は式（２）におけるＲ^２と同じ基を示す。）

(In the formula, X represents a halogen atom, and R ² represents the same group as R ² in formula (2).)

（式中、Ｒ^１は式（１）におけるＲ^１と同じ基を示す。）

(In the formula, ^{R 1} represents the same group as ^{R 1} in Formula (1).)

（式中、Ｒ^１は式（４）におけるＲ^１と同じ基を示し、Ｒ^２は式（２）におけるＲ^２と同じ基を示す。）

(In the formula, ^{R 1} represents the same group as ^{R 1} in formula (4), ^{R 2} represents the same group as ^{R 2} in formula (2).)

  Commercially available alkoxyethanol represented by the formula (2) can be used.

  Specific examples of the alkoxyethanol include methoxyethanol, ethoxyethanol, propoxyethanol, and 2-isopropoxyethanol.

  Specific examples of the organic halogen compound represented by the formula (3) include 1-chloro-2-ethoxyethane, 2- (2-chloroethoxy) propane and the like.

  A commercially available thiol sodium salt represented by the formula (4) can be used. Specific examples of the sodium salt of thiol include methyl mercaptan sodium, ethyl mercaptan sodium, propyl mercaptan sodium, and isopropyl mercaptan sodium.

  Specific examples of the sulfide compound represented by the formula (5) include (methoxyethyl) methyl sulfide, (ethoxyethyl) methyl sulfide, (propoxyethyl) methyl sulfide, (isopropoxyethyl) methyl sulfide, and (methoxyethyl) ethyl. Sulfide, (ethoxyethyl) ethyl sulfide, (propoxyethyl) ethyl sulfide, (isopropoxyethyl) ethyl sulfide, (methoxyethyl) propyl sulfide, (ethoxyethyl) propyl sulfide, (propoxyethyl) propyl sulfide, (methoxyethyl) isopropyl Sulfide, (ethoxyethyl) isopropyl sulfide, (propoxyethyl) isopropyl sulfide and the like.

  Specific examples of the halogenating agent to be reacted with the alkoxyethanol represented by the formula (2) are not particularly limited, and examples thereof include hydrogen halide, phosphorus halide, thionyl halide, acid halide and the like. Of these, thionyl halide is preferred, and thionyl chloride is more preferred.

  The use ratio of the halogenating agent is preferably 0.5 to 10 mol, more preferably 0.8 to 1.2 mol, relative to 1 mol of alkoxyethanol.

  In the reaction of alkoxyethanol with the halogenating agent, a catalyst can be used as necessary. The catalyst is not particularly limited, and a known catalyst can be used. For example, N, N-dimethylformamide and the like are preferably used. The use ratio of the catalyst is preferably 1.0 mol or less, more preferably 0.01 to 0.2 mol, relative to 1 mol of alkoxyethanol.

  In the halogenation reaction, a solvent may not be used, but may be used as necessary when the raw material is solid or the reaction solution has a high viscosity and insufficient stirring. 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 solvents may be used alone or in combination of two or more.

  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 alkoxyethanol.

  The reaction temperature is preferably 0 to 100 ° C, more preferably 40 to 80 ° C. The reaction time is usually 1 to 10 hours.

  In the reaction of the organic halogen compound represented by the formula (3) and the sodium salt of the thiol represented by the formula (4), the use ratio of the sodium salt of the thiol is 0.5 It is preferable that it is -10 mol, and it is more preferable that it is 0.5-5 mol.

  In the reaction between the organic halogen compound and the sodium salt of thiol, a solvent may not be used, but it is used as necessary when the raw material is solid or the reaction solution has a high viscosity and insufficient stirring. May be. The solvent to be used is not particularly limited. For example, methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, cyclohexanol, Alcohols such as ethylene glycol and propylene glycol, ethers such as diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, tetrahydrofuran, tetrahydropyran, and 1,4-dioxane, Nitriles such as acetonitrile, acrylonitrile, propionitrile, acetone, methyl ethyl ketone, methyl isobutyl ketone And ketones such as cyclohexanone, butyrolactone, caprolactone, hexanolactone, and esters such as ethyl acetate, sulfoxides such as dimethyl sulfoxide, pentane, hexane, heptane, octane, nonane, decane, undecane, dodecane, cyclohexane, Hydrocarbons such as petroleum ether, benzine, kerosene, toluene, xylene, mesitylene, and benzene, water, and the like can be given. Of these, methanol and water are preferably used. These solvents may be used alone or in combination of two or more.

  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 organic halogen compounds.

  The reaction temperature is preferably 0 to 200 ° C, more preferably 10 to 150 ° C. The reaction time is usually 1 to 30 hours.

  In the method for producing the sulfone compound according to the present invention, specific examples of the oxidizing agent used for the oxidation of the sulfide compound represented by the formula (5) are not particularly limited. For example, potassium permanganate, Examples thereof include chromic acid, oxygen, aqueous hydrogen peroxide, and organic peroxides such as 3-chloroperbenzoic acid. Among these, hydrogen peroxide water is preferably used.

  The ratio of the oxidizing agent used is preferably 1.8 to 10 moles, more preferably 2 to 5 moles per mole of the sulfide compound.

  When oxidizing the sulfide compound, the solvent may not be used, but may be used as necessary when the raw material is solid or the viscosity of the reaction solution is high and stirring is insufficient. 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 solvents may be used alone or in combination of two or more.

  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.

  0-200 degreeC is preferable and, as for reaction temperature, 10-150 degreeC is more preferable. The reaction time is usually 1 to 30 hours.

  The sulfone compound thus obtained can be isolated by distillation or the like after washing and liquid separation as necessary.

For example, the sulfone compound according to the present invention can be suitably used as a solvent for an electrochemical device as an electrolyte solvent.
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.

The sulfone compound according to the present invention is characterized by low water solubility. Thereby, when it uses for the said solvent for electrochemical devices, mixing of water can be suppressed and generation | occurrence | production of a fall of current efficiency, an internal pressure rise, etc. can be prevented. Moreover, since melting | fusing point is comparatively low and it is excellent in thermal stability, it can be safely used in a wide temperature range from low temperature to high temperature.
Furthermore, since the sulfone compound according to the present invention has a low viscosity, the ionic conductivity of the electrolyte can be significantly increased, and high electrical characteristics can be realized.

  The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to the examples.

Example 1
[Synthesis of (Isopropoxyethyl) methylsulfone (MSEP)]
In a 300 mL four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser, under a nitrogen atmosphere, 82.3 g (0.69 mol) of thionyl chloride and 1.84 g of N, N-dimethylformamide (0. 024 mol) was added, the temperature was raised to 60 ° C., 62.6 g (0.6 mol) of 2-isopropoxyethanol was gradually added, and the mixture was stirred at the same temperature for 1 hour.
Thereafter, 55.6 g of ultrapure water was added, the organic layer was separated, washed once with 25.6 g of ultrapure water, neutralized by adding 17.1 g of a 30 wt% aqueous sodium hydroxide solution, and the reaction solution 72.0 g was obtained.
Next, in a 300 mL four-necked flask equipped with a stirrer, a thermometer, a dropping funnel and a condenser, 61.3 g of the reaction solution (0.2 (2- (2-chloro-ethoxy) propane) was added in a nitrogen atmosphere. (5 mol) was charged, and 129.4 g (0.55 mol) of a 29.8 wt% aqueous solution of methyl mercaptan was added, followed by stirring for 15 hours while maintaining the temperature at 50 ° C. After cooling to room temperature, the organic layer was separated and washed twice with 50 g of 5% by weight diluted sulfuric acid. To the obtained organic layer was added 80.7 g (0.82 mol) of 35 wt% aqueous hydrogen peroxide, and the mixture was stirred for 1 hour while maintaining at 40 ° C., and the organic layer was distilled to obtain (isopropoxy) as a colorless transparent liquid. 61.2 g of ethyl) methylsulfone were obtained. The yield of the obtained (isopropoxyethyl) methyl sulfone was 61.3% with respect to 2-isopropoxyethanol.

  The obtained (isopropoxyethyl) methylsulfone could be identified from the following physical properties.

^1- H-NMR (400 MHz, solvent: CDCl ₃ ): 1.17 (d, J = 6.4 Hz, 6H), 3.02 (s, 3H), 3.20 (t, J = 5.4 Hz, 2H), 3.64 (m, 1H), 3.85 (t, J = 5.4, 2H)

  The melting point and exothermic onset temperature of the obtained (isopropoxyethyl) methylsulfone were measured using a differential scanning calorimeter in a nitrogen atmosphere. The solubility of water was determined by measuring the water content of the sulfone compound in which water was saturated and dissolved using a Karl Fischer coulometric titrator. Furthermore, the viscosity was measured using a rotational viscometer (trade name “DISITAL VISCOMETER” manufactured by Tokimec Co., Ltd.).

Table 1 shows the measurement results of the melting point, heat generation starting temperature, water solubility and viscosity of the sulfone compound obtained in Example 1, together with propylene carbonate as Comparative Example 1 and sulfolane as Comparative Example 2.
Table 1

Claims (3)

Formula (1):

(In the formula, ^{R 1} represents a methyl or ethyl group, ^{R 2} represents an alkyl group having a carbon number of 1-3.) Electrochemical device for solvent represented by. ^{2. The} solvent for an electrochemical device according to claim 1, wherein in Formula (1), R ¹ is a methyl group, and R ² is a group selected from a propyl group or an isopropyl group. The solvent for an electrochemical device according to claim ¹ , wherein R ¹ is an ethyl group and R ² is an isopropyl group in the formula (1).