JPH1180112A - Production of cyanoethyl compound for lithium or lithium ion secondary battery electrolyte - Google Patents

Abstract

PROBLEM TO BE SOLVED: To readily produce the subject high-purity compound without causing polymerization of acrylonitrile and discoloring by carrying out the cyanoethylating reaction of a specific compound with the acrylonitrile in the presence of a specified catalyst in a nonaqueous system. SOLUTION: The cyanoethylating reaction of (A) a compound having 1-4 hydroxyl groups (a hydroxyl group-containing compound) with (B) acrylonitrile is carried out in the presence of (C) a reactional catalyst which is at least one selected from the group of compounds, composed of (i) lithium hydroxide and (ii) metallic lithium, lithium alkoxides or compounds composed of lithium and an active methylene compound such as lithium acetylacetonate and capable of manifesting effects substantially equivalent to those of the component (i) in an amount of 0.001-5 wt.%, based on the total amount of the components A and B and expressed in terms of the lithium in a nonaqueous system to afford the objective compound represented by the formula (R1 O)a R2 (OCH2 CH2 CN)b R1 is a 1-3C alkyl; R2 is a residue after removing all the hydroxyl groups from a hydroxyl group-containing compound; (a) is 0-3; (b) is 1-4; [(a)+(b)] is 1-4}.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a cyanoethyl compound for use as an electrolyte in a lithium or lithium ion secondary battery, and more particularly, to a method for producing a cyanoethyl compound of a compound having a hydroxyl group and acrylonitrile using a specific reaction catalyst. The present invention relates to a method for producing a cyanoethyl compound which suppresses the production of bis (2-cyanoethyl) ether by carrying out a cyanoethylation reaction in an aqueous system, and does not cause polymerization of acrylonitrile and the accompanying coloring.

[0002]

2. Description of the Related Art Conventionally, a cyanoethylation reaction between a compound having a hydroxyl group and acrylonitrile usually involves caustic alkali (NaOH, KO).
H), a catalyst such as a quaternary ammonium base is used,
And water is used as a medium. Among them, cyanoethyl compounds produced using sodium hydroxide, which is exclusively economical and easily available; cyanoethylated polyvinyl alcohol, cyanoethylated pullulan, or partially cyanoethylated polyhydric alcohol (meth) acrylate obtained by radical polymerization Molecular compounds and the like are mainly used as binder resins for organic dispersion-type electroluminescence. Further, the cyanoethyl compound shows good ionic conductivity, and the polymerized material is a battery material,
Particularly, application to an electrode binder resin of a lithium or lithium ion secondary battery, a matrix resin of a gel-type solid electrolyte, and the like are being studied. Furthermore, low molecular cyanoethyl compounds also utilize ionic conductivity and are being studied for organic electrolytes, gel-type solid electrolytes, and the like for these batteries.

[0003] These low-molecular cyanoethyl compounds are produced by similarly cyanoethylating a compound having a low-molecular hydroxyl group with acrylonitrile. However, it is necessary to reduce the residual amount of hydroxyl groups as much as possible. It is preferable to completely convert the hydroxyl group to a cyanoethyl group by a method such as using acrylonitrile. However, if an excess of acrylonitrile is used, water as a medium is cyanoethylated, and bis (2-cyanoethyl) ether
[NCCH ₂ CH ₂ OCH ₂ CH ₂ CN] was found to be easily formed. Bis (2-cyanoethyl) ether is also originally a cyanoethyl compound and not an adverse compound. Therefore, even when provided in the form of a mixture, it is difficult to control the production ratio, and the content changes for each production batch. This causes many problems.

In order to minimize the formation of this by-product, the dropping rate of acrylonitrile is slowed down in accordance with the amount of acrylonitrile consumed in the reaction to minimize the acrylonitrile concentration in the reaction system, and to use acrylonitrile. Although the production can be suppressed to some extent by not using an amount larger than the equivalent to the hydroxyl group, there is a problem that the remaining amount of hydroxyl group in the obtained cyanoethyl compound is increased and the quality is reduced. Although this problem can be solved by a separation means such as fractionation, productivity is remarkably reduced, resulting in an increase in cost and a decrease in yield. Further, in order to prevent cyanoethylation of water, it is expected that the reaction can be solved by reacting in non-aqueous solution.In this case, however, polymerization of acrylonitrile occurs due to the presence of a caustic alkali or an organic base, and remarkable depending on the polymerization. Coloring
(Brown-black-brown: believed to be cyclopolymerization of acrylonitrile with alkali and base), which proved unsolved.

Accordingly, the present inventors have conducted intensive studies on the production of bis (2-cyanoethyl) ether and the prevention of polymerization and coloring of acrylonitrile in the production of such a conventional cyanoethyl compound. If lithium hydroxide or its equivalent is used as a catalyst and the cyanoethylation reaction is performed in non-aqueous solution,
The present inventors have found that bis (2-cyanoethyl) ether is not generated at all, and there is no polymerization or coloring of acrylonitrile, and a high-purity cyanoethyl compound can be easily obtained, thereby completing the present invention.

Namely, the present invention has the formula: (R ₁ O) aR ₂ in _{(OCH 2 CH 2 CN) b} [ wherein, R ₁ represents an alkyl group having 1 to 3 carbon atoms; R ₂ is a 1-4 A residue having all hydroxyl groups removed from a compound having a hydroxyl group (hereinafter, referred to as a hydroxyl group-containing compound); a is 0 to 3; and b
Is from 1 to 4 (where a + b is from 1 to 4). The method according to claim 1, wherein the cyanoethyl compound is produced by a cyanoethylation reaction of the hydroxyl group-containing compound and acrylonitrile. As a catalyst, (a) lithium hydroxide; and (b) a metal lithium; lithium alkoxides; a compound consisting of lithium and an active methylene compound such as lithium acetylacetonate; which has an effect substantially equivalent to lithium hydroxide; An object of the present invention is to provide a method for producing a cyanoethyl compound, comprising performing a cyanoethylation reaction under non-aqueous condition using at least one member selected from the group.

The hydroxyl group-containing compound includes: (a) a monohydric alcohol having 1 to 6 carbon atoms (eg, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, etc.); Dihydric alcohols such as glycols such as ethylene glycol, propylene glycol, neopentyl glycol, butanediol, and hexylene glycol; triglycols such as glycerin, trimethylolpropane, erythritol and pentaerythritol
Tetrahydric alcohols; polyethylenes such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol);

(C) Partial alkyl ethers of glycols or polyglycols (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene Glycol monoethyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polyethylene glycol monobutyl ether, polypropylene glycol monomethyl ether, etc.); (d) polyoxyalkylene having a molecular weight of 600 or less Polyols (For example, polyoxyethylene triol, polyoxypropylene triol, polyoxyethylene tetraol, etc. obtained by addition polymerization of ethylene oxide and / or propylene oxide to glycerin, trimethylolpropane, pentaerythritol, etc.); or

(E) ammonia or an amine compound such as triethanolamine, triisopropanolamine, N- (2-hydroxyethyl) diethylamine, N,
N-bis (2-hydroxyethyl) ethylamine, N, N
-Bis (2-hydroxyethyl) 1-propylamine,
N, N, N ', N'-tetrakis (2-hydroxyethyl) ethylenediamine, N, N, N', N'-tetrakis (2-hydroxypropyl) ethylenediamine, etc.] and alkylene oxide (ethylene oxide and / or propylene oxide) And N-mono to polyoxyalkylene polyols having a hydroxyl group at the molecular terminal and having a molecular weight of 600 or less, obtained by addition-polymerizing the above. If the molecular weight of the hydroxyl group-containing compounds (d) and (e) exceeds 600, the resulting cyanoethyl compound tends to have low ionic conductivity or too high viscosity, which is not preferable.

The present invention is characterized by the use of lithium hydroxide (including hydrates) as a catalyst for the above cyanoethylation reaction. In addition, the present invention provides a compound having an effect substantially equivalent to lithium hydroxide. (Equivalent), for example, lithium metal; lithium alkoxides (lithium methyl alcoholate,
Lithium ethyl alcoholate, ethylene glycol lithium bis alcoholate, etc.); a compound composed of lithium and an active methylene compound (acetylacetone, diethyl malonate, ethyl acetoacetate, dinitrile malonate, etc.),
For example, lithium acetylacetonate may be used. The amount of the reaction catalyst used is usually 0.0% in terms of lithium content based on the total amount of the hydroxyl group-containing compound and acrylonitrile.
The selection may be made in the range of 01 to 5% (% by weight, the same applies hereinafter). If it is less than 0.001%, the progress of the cyanoethylation reaction is slow, and if it exceeds 5%, there is a problem that the solubility of the catalyst is poor under non-aqueous conditions, and it takes time to remove (purify) the catalyst.

The above-mentioned cyanoethylation reaction is usually carried out in a predetermined amount while stirring at a temperature of about room temperature to about 60 ° C. in the presence of the above-mentioned reaction catalyst (lithium compound), a hydroxyl group-containing compound and, if necessary, a medium such as an organic solvent. The reaction is carried out by dropwise addition of acrylonitrile. By using a lithium compound such as lithium hydroxide as a reaction catalyst in this manner, polymerization of acrylonitrile does not occur, and some catalyst components (Li
Even if the (ion) remains, its adverse effect is small and purification can be simplified, which is very convenient. The reason for this is not clear, but it is presumed that the basicity of lithium hydroxide is probably smaller than other caustic alkalis and organic bases.

[0012] At least one of the cyanoethyl compounds prepared according to the present invention may be added to a conventional lithium salt (eg, LiClO ₄ , LiSCN, LiBF ₄ , LiAsF ₆ , LiCF).
By dissolving ₃ SO ₃ , LiPF ₆ or the like, it can be used as an organic electrolyte for lithium or lithium ion secondary batteries. Here, in addition to the cyanoethyl compound that functions as an electrolyte solvent, other conventionally used aprotic polar solvents (e.g., diethyl carbonate, ethylene carbonate, propylene carbonate, N-methylpyrrolidone,
γ-butyrolactone, dimethylsulfoxide, sulfolane, N, N′-tetramethylurea, ethyl cyanoacetate, acetonitrile, propionitrile, succinonitrile,
Dioxane, trioxane, tetrahydrofuran, dimethoxyethane, diethoxyethane, triacetin, triethyl phosphate, nitromethane, nitroethane, nitropropane, etc.) can also be used in combination. In this case, the cyanoethyl compound may be selected in a range of 10% by weight or more based on the total amount of the other aprotic polar solvents. 10
If the amount is less than the weight percentage, the use effect of the cyanoethyl compound tends to be not exhibited.

The cyanoethyl compound according to the production method of the present invention can be obtained as a liquid having a high boiling point and a low viscosity and a high coagulation temperature and a high solidification temperature. Although it is useful for application to organic electrolytes, it is also possible to include a suitable matrix resin to obtain a gel-type solid electrolyte. In this case, a gel-type solid electrolyte is obtained by swelling the matrix resin with the cyanoethyl compound. As the matrix resin, SBR,
Examples thereof include a hydrocarbon chain-containing polymer such as NBR and a cyanoethylated polymer of the polymer; a fluorinated polymer such as vinylidene fluoride and a cyanoethylated polymer of the polymer; a cyanoethylated polyurethane; and a cyanoethylated acrylic polymer.

[0014]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 In a four-necked flask, 124.2 g (2 mol) of ethylene glycol as a hydroxyl-containing compound and lithium hydroxide (LiOH) were added.
· H ₂ O) was charged 0.1 g, heating and stirring until dissolution is LiOH · H ₂ O at 60 ° C.. Next, while maintaining the temperature at 40 to 50 ° C., 222.8 g of acrylonitrile (4.2 mol: 1.05 mol per mol of hydroxyl group of the hydroxyl group-containing compound) was added to 2 parts.
Drip over time. After dropping, keep the temperature at 3
After continuing stirring for 200 hours, 200 g of methylene chloride and 500 ml of ion-exchanged water are added, and the mixture is stirred for several minutes. When the stirring is stopped and the mixture is allowed to stand, it separates into two layers, and the upper aqueous layer is separated and discarded.
Further, similarly, washing with water is performed twice using ion-exchanged water, drying is performed using a vacuum pump, and low volatile components are removed to obtain a target product. The obtained target is a colorless and transparent low-viscosity liquid,
Ethylene glycol bis according to infrared absorption spectrum
It was confirmed to be (2-cyanoethyl) ether (symbol 2CE-EG), and the gas chromatographic purity was 99.5% or more.

Example 2 A four-necked flask was charged with 124.2 g (2 mol) of ethylene glycol and 0.02 g of lithium metal powder which had been dehydrated with a molecular sieve in advance, and heated at 60 ° C. for 1 hour while introducing dry nitrogen gas. Let react. Thereafter, while maintaining the temperature at 40 to 50 ° C. as in Example 1, acrylonitrile 22
2.8 g (4.2 mol) was added dropwise over 2 hours, followed by successive extraction with methylene chloride, washing with pure water, and drying to obtain the desired product. Similarly, the infrared absorption spectrum confirmed that the product was ethylene glycol bis (2-cyanoethyl) ether, and the gas chromatographic purity was 99.5% or more.

Examples 3 to 29 In the same manner as in Examples 1 and 2, the corresponding cyanoethyl compounds were produced using the hydroxyl group-containing compounds shown in Tables 1 to 5 below. In the same manner as above, the charged amount was 2 mol of the hydroxyl group-containing compound, acrylonitrile was 1.05 mol with respect to 1 mol of the hydroxyl group of the hydroxyl group-containing compound, and LiOH.H ₂
O is 0.1 g.

[0017]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

COMPARATIVE EXAMPLE 1 In a four-necked flask, 124.2 g (2 mol) of ethylene glycol and sodium hydroxide were used as hydroxyl-containing compounds.
100 g of a 5% aqueous solution is charged, and while maintaining the temperature at 40 to 50 ° C., 222.8 g of acrylonitrile (4.2 mol: 1.05 mol per mol of hydroxyl group of the hydroxyl group-containing compound) is added dropwise over 2 hours. After completion of the dropwise addition, stirring was continued at the same temperature for 3 hours, then 200 g of methylene chloride and 500 ml of ion-exchanged water were added, and the mixture was stirred for several minutes. When the stirring is stopped and the mixture is allowed to stand, the mixture is separated into two layers. The upper aqueous layer is separated and discarded, and then similarly washed twice using ion-exchanged water, dried using a vacuum pump, and dried to remove low volatile components. Removal gave a colorless and transparent low-viscosity liquid. According to the infrared absorption spectrum and gas chromatograph, ethylene glycol bis
The contents of 68.6% of (2-cyanoethyl) ether and 31.4% of bis (2-cyanoethyl) ether as a by-product were confirmed.

Comparative Example 2 124.2 g (2 mol) of ethylene glycol and 0.1 g of sodium hydroxide were used as a hydroxyl-containing compound in a four-necked flask.
And heated and stirred at 60 ° C. until the sodium hydroxide is dissolved. Next, while maintaining the temperature at 40 to 50 ° C., 222.8 g (4.2 mol) of acrylonitrile is added dropwise over 2 hours. After about 1.5 hours from the start of the dropwise addition, the reaction solution gradually began to turn brown, and the coloring was intense even after the completion of the dropwise addition.
The stirring was continued at the same temperature, but the color changed from brown to black-brown, and a brown precipitate was formed. When the liquid portion was analyzed by gas chromatography, no formation of bis (2-cyanoethyl) ether was observed, but several unidentifiable peaks were observed on the high boiling point side.

Example 30 (Blending of electrolytic solution) Lithium salt was dissolved in the amount of a cyanoethyl compound and, if necessary, other aprotic polar compounds in the amounts shown in Tables 6 and 7 below, followed by dehydration with a molecular sieve of 3 Å. The conductivity at 20 ° C. and 1 KHz was measured using an LCZ meter. The results are shown in Tables 6 and 7.

[Table 6]

[Table 7]

[0021]

According to the production method of the present invention having the above constitution, a high purity cyanoethyl compound can be easily obtained without producing any bis (2-cyanoethyl) ether and without polymerizing or coloring acrylonitrile. it can. Furthermore, in the production method of the present invention, since the above-mentioned by-product does not occur even if excess acrylonitrile is present, an excess amount of acrylonitrile can be used relative to the hydroxyl group-containing compound, and a high quality cyanoethyl compound having an extremely low residual hydroxyl group amount can be used. Is obtained,
Further, it is possible to increase the dropping rate of acrylonitrile, and the productivity is remarkably improved. Further, since the catalyst is a lithium compound, the remaining ions are lithium ions, and the catalyst is used in the electrolyte of lithium or lithium ion secondary batteries. If the remaining catalyst is neutralized with perchloric acid or trifluoromethanesulfonic acid, etc., the purification step can be simplified, and the electrolyte salt itself used in the electrolytic solution can be obtained. It is also possible to provide such a method, which is a very useful method.

Claims (7)

[Claims] 1. A compound having the formula: (R ₁ O) aR ₂ (OCH ₂ CH ₂ CN) b wherein R ₁ is an alkyl group having 1 to 3 carbon atoms; R ₂ is a compound having 1 to 4 hydroxyl groups. (Hereinafter, referred to as a hydroxyl group-containing compound) residues obtained by removing all hydroxyl groups; a is 0 to 3; and b
Is from 1 to 4 (where a + b is from 1 to 4). The method for producing a cyanoethyl compound according to claim 1, wherein the cyanoethyl compound is produced by a cyanoethylation reaction of the hydroxyl-containing compound and acrylonitrile.
As the reaction catalyst, (a) lithium hydroxide; and (b) a compound comprising lithium and an active methylene compound such as lithium metal; lithium alkoxides; lithium acetylacetonate, which has an effect substantially equivalent to lithium hydroxide. A method for producing a cyanoethyl compound, wherein a cyanoethylation reaction is carried out in non-water using at least one member selected from the group consisting of: 2. The reaction catalyst is calculated to have a lithium content of 0.001 to the total amount of the hydroxyl group-containing compound and acrylonitrile.
The method for producing a cyanoethyl compound according to claim 1, which is used in an amount of from 5 to 5% by weight. 3. A compound containing a hydroxyl group, comprising: (a) a monohydric alcohol having 1 to 6 carbon atoms; (b) a dihydric alcohol having 2 to 6 carbon atoms; (c) a part of a glycol or a polyglycol. Alkyl ethers; (d) polyoxyalkylene polyols having a molecular weight of 600 or less; or (e) N-mono to polyoxyalkylene polyols having a hydroxyl group at the molecular terminal having a molecular weight of 600 or less, obtained by addition-polymerizing an alkylene oxide to ammonia or an amine compound. The method for producing a cyanoethyl compound according to claim 1 or 2, wherein 4. The polyoxyalkylene polyol (d) or the N-mono-polyoxyalkylene polyol (e) having a molecular weight of 600 or less, wherein the polyoxyalkylene unit is polyoxyethylene and / or polyoxypropylene. The method for producing a cyanoethyl compound according to claim 3. 5. An organic electrolyte for a lithium or lithium ion secondary battery obtained by dissolving a lithium salt in at least one of the cyanoethyl compounds obtained by the production method according to claim 1. 6. The organic electrolyte according to claim 5, wherein a cyanoethyl compound and another aprotic polar compound are used in combination. 7. The organic electrolyte according to claim 6, wherein the cyanoethyl compound is used in an amount of 10% by weight or more based on the total amount of the other aprotic polar compounds.