JP5647820B2 - Method for producing phosphoric acid diester salt - Google Patents

Description

  The present invention relates to a method for producing a phosphoric acid diester salt. More specifically, the present invention relates to a method for producing a high-purity phosphoric acid diester salt that does not contain organic impurities such as phosphoric acid, phosphoric acid monoester, and phosphoric acid triester, and ionic impurities such as sodium ions and chloride ions.

A general method for producing a phosphoric acid diester salt is a method in which a phosphoric acid diester is neutralized with a base (such as an amine) or a cation exchange of the phosphoric acid diester salt is performed to obtain a target salt. The salt obtained by these methods can be used as an electrolyte of an electrolytic solution for an aluminum electrolytic capacitor, for example.
By the way, as a manufacturing method of phosphoric acid diester, the method of manufacturing by reacting alcohol, phosphorus halides, such as phosphorus oxychloride, diphosphorus pentoxide, polyphosphoric acid, etc. is generally known. In order to avoid organic impurities and ionic impurities, not only for capacitors but also for electronic materials, high-purity materials are desired for use. Since this method mainly results in a mixture of phosphoric acid monoester and phosphoric acid diester, various methods have been developed to increase the purity of the phosphoric acid diester.

  For example, Japanese Patent Application Laid-Open No. 2004-269421 discloses a method in which a phosphoric acid triester is hydrolyzed with an aqueous inorganic base in the presence of a phosphoric acid diester to obtain a corresponding phosphoric acid diester (Patent Document 1).

JP 2004-269421 A

  In the method of Patent Document 1, since an inorganic base is used, metal ions such as sodium and potassium may be mixed, and since water is used during production, a small amount of phosphoric monoester and phosphoric acid are generated. There is.

  Then, it aims at providing the manufacturing method which can obtain the phosphoric acid diester salt which does not contain an impurity substantially with high yield and high purity.

The inventor of the present invention has arrived at the present invention as a result of studies to achieve the above object.
That is, in the present invention, the phosphate triester (A) represented by the general formula (1) and the secondary amine (B) represented by the general formula (2) are reacted in the absence of water , When 1 mol of A) and 1 mol of (B) are reacted, the phosphoric acid diester salt (C) represented by the general formula (3) is obtained, and (A) 1 mol and (B) more than 1 mol 2 When an amount less than the mole is reacted, a mixture of the phosphoric diester salt (D) represented by the general formula (4) and the phosphoric diester salt (C) is obtained, and the obtained phosphoric diester salt ( C) or a mixture thereof and the pKa of the corresponding acid XH of the counter anion X ^{− is} the corresponding acid HOP (O) (OR ² ) (OR ³ ) of the counter anion [PO ₂ (OR ² ) (OR ³ )] ⁻ The amidinium salt (J) represented by the general formula (8) having a larger pKa is allowed to react. A method for producing Berlin diester salt to give the phosphoric acid diester salt (K) represented by the general formula (9).

［式（１）中、Ｒ^１〜Ｒ^３は同一でも異なっていても良い炭素数１〜２０の炭化水素基を
表す。］

[To display the hydrocarbon radical of the formula (1) ^in, R 1 to R ³ to 20 carbon atoms which may be the same or different. ]

［式（２）中、Ｒ^４〜Ｒ^５は同一でも異なっていても良い炭素数１〜２０の炭化水素基を表す。Ｒ^４とＲ^５は互いに結合して環構造を形成していてもよい。］

［式（３）中、Ｒ ^１ 〜Ｒ ^３ は一般式（１）と同じであり、Ｒ ^４ 〜Ｒ ^５ は一般式（２）と同じである。］

［式（４）中、Ｒ ^２ 〜Ｒ ^３ は一般式（１）と同じであり、Ｒ ^４ 〜Ｒ ^５ は一般式（２）と同じ
である。］

［式（８）中、Ｒ ^１０ 〜Ｒ ^１３ は同一でも異なっていてもよく、炭素数１〜２０の炭化水素基であり、Ｒ ^１４ は水素原子、炭素数１〜２０の炭化水素基であり、Ｒ ^１０ 〜Ｒ ^１４ のうち２つ以上の基が互いに結合して環構造を形成していてもよく、Ｘ ^‐ は陰イオンを表す。］

［式（９）中、Ｒ ^２ 〜Ｒ ^３ は一般式（１）と同じであり、Ｒ ^１０ 〜Ｒ ^１４ は一般式（８）と同じである。］

[In formula (2), R ^{4 to} R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms which may be the same or different. R ⁴ and R ⁵ may be bonded to each other to form a ring structure. ]

Wherein ^(3), R 1 ~R 3 is the same as the general formula ^(1), R 4 ~R ⁵ are the same as in the formula (2). ]

[In formula (4), R ^{2 to} R ³ are the same as in general formula (1), and R ^{4 to} R ⁵ are the same as in general formula (2).
It is. ]

[In Formula (8), R ^{10 to} R ¹³ may be the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms; R ¹⁴ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; , R ^{10 to} R ¹⁴ may be bonded to each other to form a ring structure, and X ⁻ represents an anion. ]

[In formula (9), R ^{2 to} R ³ are the same as in general formula (1), and R ^{10 to} R ¹⁴ are the same as in general formula (8). ]

  In the present invention, a phosphoric acid diester salt can be produced without using an inorganic base, so that there is no fear that metal ions such as sodium and potassium are mixed, and since water is not used during the production, a small amount of phosphoric acid monoester by hydrolysis is used. Does not produce esters and phosphoric acid. Therefore, a phosphoric diester salt substantially free of impurities can be obtained in high yield and high purity.

The method for producing a phosphoric acid diester salt according to the present invention comprises a phosphoric acid triester (A) represented by the general formula (1) and a secondary amine (B) represented by the general formula (2) in the absence of water. It is a production method to be reacted below, and does not produce metal ions such as sodium and potassium, a small amount of phosphoric monoester and phosphoric acid by hydrolysis, and is substantially free of impurities.
Here, the phosphate diester salt refers to a salt of a phosphate diester anion and an ammonium cation.

Here, “in the absence of water” means that water is not intentionally added for the purpose of promoting hydrolysis or other reactions, and there may be a trace amount of water contained in raw materials, solvents and the like.
In consideration of side reactions such as hydrolysis, the water content of the raw material used for the reaction is preferably 0.5% by weight or less.

  The phosphoric acid triester (A) in the present invention is represented by the following general formula (1).

In formula (1), R ^{1 to} R ³ represent the same or different hydrocarbon group having 1 to 20 carbon atoms, and two or more groups of R ^{1 to} R ³ are bonded to each other to form a ring structure May be formed.

The hydrocarbon group having 1 to 20 carbon atoms that may be the same or different in R ^{1 to} R ³ in formula (1) contains an alkyl group, an alkenyl group, an alkynyl group, an oxygen atom, or a sulfur atom. Examples of the alkyl group include straight chain alkyl groups such as methyl, ethyl, n-propyl, and n-butyl, branched alkyl groups such as isopropyl, sec-butyl, and tert-butyl, and cycloalkyl groups. And cyclic alkyl groups such as propyl, cyclopentyl and cyclobutyl. Preferred from the viewpoint of reactivity is an alkyl group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably an unsubstituted alkyl group at the 1-position of 1 to 6 carbon atoms.

  Examples of the alkenyl group include vinyl, allyl, propenyl, 1-butenyl, 2-butenyl and the like. From the viewpoint of reactivity, preferred are those having 2 to 10 carbon atoms, more preferred are those having 2 to 8 carbon atoms, and most preferred are those having 3 to 6 carbon atoms in which the double bond position is not the 1st position.

  Examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl and the like. From the viewpoint of reactivity, preferred are those having 2 to 10 carbon atoms, more preferred are those having 2 to 8 carbon atoms, and most preferred are those having 2 to 6 carbon atoms in which the triple bond position is not the 1st position.

  Examples of the aromatic hydrocarbon group which may contain an oxygen atom or a sulfur atom include heterocyclic aromatic compound groups such as phenyl, tolyl, naphthyl, anthracenyl and the like, as well as furanyl and thienyl.

In the formula (1), two or more groups of R ^{1 to} R ³ may be bonded to each other to form a ring structure. Specific examples of the group formed by bonding two groups to each other include methylene, ethylene , Linear alkylene groups such as propylene, butylene, 1-methylethylene, 1,1-dimethylethylene groups, branched alkylene groups such as 1,2-dimethylethylene, 1,3-cyclopentylene, 1,4-cyclohexylene And cyclic alkylene groups such as 1,2-cyclohexylene.

In formula (1), R ^{1 to} R ³ are preferably all the same from the viewpoint of industrial availability.

Preferable specific examples of R ^{1 to} R ³ include trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, triisopropyl phosphate, tri (n-butyl) phosphate, tri (2-ethylhexyl) phosphate, tri (N-butoxyethyl) phosphate, tribenzyl phosphate, triallyl phosphate, triphenyl phosphate, trinaphthyl phosphate, ethylene-monomethyl phosphate, 2,2-dimethyl-1,3-propylene-monoethyl phosphate (2,2′-biphenylene-monoethyl phosphate, 1,1′-binaphthyl-2,2′-diyl-monoethyl phosphate, and the like.

More preferred are trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, triisopropyl phosphate, tri (n-butyl) phosphate, tri (2-ethylhexyl) phosphate, tri (n-butoxyethyl) phosphate. And most preferred are trimethyl phosphate, triethyl phosphate, tri (n-propyl) phosphate, tri (n-butyl) phosphate.

The secondary amine (B) in the present invention is represented by the following general formula (2).

In formula (2), R ^{4 to} R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms which may be the same or different. R ⁴ and R ⁵ may be bonded to each other to form a ring structure.

In the formula (2), the hydrocarbon group having 1 to 20 carbon atoms which may be the same or different may be an aromatic hydrocarbon which may contain an alkyl group, an alkenyl group, an alkynyl group, an oxygen atom or a sulfur atom. An aromatic hydrocarbon group, and as the alkyl group, a straight chain alkyl group such as methyl, ethyl, n-propyl and n-butyl, a branched alkyl group such as isopropyl, sec-butyl and tert-butyl, cyclopropyl, And cyclic alkyl groups such as cyclobutyl and cyclopentyl. Preferred from the viewpoint of reactivity is an alkyl group having 1 to 10 carbon atoms, more preferably 1 to 8 carbon atoms, and most preferably an unsubstituted alkyl group having 1 to 8 carbon atoms.

Examples of the alkenyl group include vinyl, allyl, propenyl, 1-butenyl, 2-butenyl and the like. From the viewpoint of reactivity, those having 2 to 10 carbon atoms are preferred, and those having 2 to 8 carbon atoms are more preferred.

  Examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl and the like. From the viewpoint of reactivity, those having 2 to 10 carbon atoms are preferred, and those having 2 to 8 carbon atoms are more preferred.

  Examples of the aromatic hydrocarbon group which may contain an oxygen atom or a sulfur atom include heterocyclic aromatic compound groups such as phenyl, tolyl, naphthyl, anthracenyl and the like, as well as furanyl and thienyl.

In formula (2), R ^{4 to} R ⁵ may be bonded to each other to form a ring structure. Specific examples thereof include linear alkylene groups such as ethylene, propylene and butylene, 1-methylethylene, 1,1 -Branched alkylene groups such as dimethylethylene and 1,2-dimethylethylene, cyclic alkylene groups such as 1,3-cyclopentylene, 1,4-cyclohexylene and 1,2-cyclohexylene.

Preferred examples of R ^{4 to} R ⁵ include dimethylamine, diethylamine, methylethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, isopropylmethylamine, diallylamine, allylethylamine, dibenzylamine. N-methylethanolamine, diethanolamine, N, N-dimethylaminoethylmethylamine, aziridine, azetidine, pyrrolidine, piperidine, N-methylpiperazine, morpholine, N-methylaniline, methylnaphthylamine and the like.

  More preferred are dimethylamine, diethylamine, methylethylamine, di-n-propylamine, N-methylethanolamine, pyrrolidine, piperidine and morpholine from the viewpoint of reactivity.

  The reaction temperature of the phosphoric acid triester (A) and the secondary amine (B) is preferably 60 ° C to 200 ° C, more preferably 80 ° C to 150 ° C. Above 60 ° C, the reaction is fast and efficient, and phosphoric acid triesters are usually stable below 200 ° C.

  The reaction of the phosphoric acid triester (A) and the secondary amine (B) may use a solvent as necessary. Solvents include alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, nitriles such as acetonitrile and propionitrile, ethers such as diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran and 1,4-dioxane, ethylene Glycols such as glycol, propylene glycol, hydrocarbons such as pentane, hexane, cyclohexane, toluene, xylene, amides such as dimethylformamide, dimethylacetamide, N-methylpyrrolidone, triethylamine, methyldiethylamine, tetramethylethylenediamine, Tertiary amines such as pyridine, nitromethane, chloroform, dichloromethane, dimethyl sulfoxide, sulfolane and the like can be mentioned.

The reaction ratio of the phosphoric acid triester (A) and the secondary amine (B) is (B) / (A) = 10/1 to 1/1 in terms of molar ratio, more preferably 5/1 to 1/1. is there.
When (B) / (A) is 10 or less, the reaction is efficient. When (B) / (A) is 1 or more, the reaction time does not become long, and the excess phosphate triester can be easily removed and the purity is high. improves.

  According to the production method of the present invention, different production can be achieved by changing the reaction ratio of the phosphoric acid triester (A) and the secondary amine (B) according to the purpose.

  When the reaction ratio of the phosphoric acid triester (A) and the secondary amine (B) is a molar ratio (B) / (A) = 1/1, a phosphoric acid diester salt represented by the following general formula (3) ( C) can be synthesized.

In formula (3), R ^{1 to} R ⁵ are as described in general formula (1) and general formula (2).

  When the reaction molar ratio (B) / (A) between (A) and (B) is 2 or more, the phosphoric acid diester salt (D) represented by the following general formula (4) can be synthesized.

In formula (4), R ^{1 to} R ⁵ are as described in general formula (1) and general formula (2).
In addition, when the reaction molar ratio (B) / (A) of (A) and (B) is larger than 1 and smaller than 2, it becomes a mixture of salt (C) and salt (D). The molar ratio of (C) and (D) is considered to be (C) :( D) = (x−1) :( 2-x) when (B) / (A) is x.

According to the production method of the present invention, an amine having a value larger than the pKa of the secondary amine (B) with respect to the phosphoric diester salt obtained by the reaction of the phosphoric triester (A) and the secondary amine (B) ( By reacting E), the phosphoric acid diester salt (F) represented by the general formula (5) can be produced.

In formula (5), R ^{2 to} R ³ are the same as in general formula (1).

  Here, pKa will be described. pKa represents the logarithmic value of the reciprocal of the acid dissociation constant, and it can be said that the smaller the value, the easier the proton is released, that is, the stronger acid. The basicity of a base such as an amine can be compared based on the pKa value of the conjugate acid. The larger the pKa of the conjugate acid, the more difficult it is to release protons, that is, the stronger the basicity.

pKa is published in various documents and can be cited. For example, “Chemical Handbook Basics II (Chemical Society of Japan)” is helpful. Further, not only the pKa, but also the acid (base) strength of the compounds can be compared, the pKa value can be referred to. For example, “Journal of Synthetic Organic Chemistry, Japan 2005, vol. 63, No. 25, Yoshinori Kondo (pages 35-45)” shows the pK _BH value instead of the pKa value for the basic order of the compound.

  The amine (E) can be used without particular limitation as long as it has a value larger than the pKa of the secondary amine (B). Besides ordinary amines, compounds called organic super strong bases such as amidine compounds and guanidine compounds can also be used suitably. Here, the organic super strong base is a compound generally showing a pKa value of 12 or more, and specific examples include 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [ 4.3.0] -5-nonene, 1,5,7-triazabicyclo [4.4.0] -5-decene, Nt-butyl-phosphate imide = hexamethyltriamide, 2,8 , 9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo [3.3.3] undecane and the like.

Examples of combinations of secondary amine (B) and amine (E) include diethylamine (pKa: 10.9) and 1,5-diazabicyclo [4.3.0] -5-nonene (pKa: 12.7), Piperidine (pKa: 11.1) and 1,8-diazabicyclo [5.4.0] -7-undecene (pKa: 12.5), morpholine (pKa: 8.5) and -triethylamine (pKa: 10.7) ), Diethanolamine (pKa: 8.9), n-butylamine (pKa: 10.6), and the like.

In the reaction for obtaining the phosphoric acid diester salt (E), a solvent may be used as necessary. What was illustrated by reaction of phosphoric acid triester (A) and secondary amine (B) is used suitably as a solvent. The molar ratio of the amine (D) used is preferably 1 to 5 moles relative to the phosphoric diester salt (C).

  According to the production method of the present invention, the ammonium salt (G) represented by the following general formula (6) with respect to the phosphoric acid diester salt obtained by the reaction of the phosphoric acid triester (A) and the secondary amine (B). Can be further reacted to produce the phosphoric acid diester salt (H) represented by the general formula (7).

In formula (6), R ^{6 to} R ⁹ may be the same or different, and are a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and two groups out of R ^{6 to} R ⁹ are bonded to each other. Thus, a ring structure may be formed, and X ⁻ represents an anion.

In formula (7), R ^{2 to} R ³ are the same as in general formula (1), and R ^{6 to} R ⁹ are as described in general formula (6).

As a C1-C20 hydrocarbon group in R < ⁶ > -R < ⁹ > in Formula (6), the aromatic hydrocarbon aromatic which may contain the alkyl group, the alkenyl group, the alkynyl group, the oxygen atom, or the sulfur atom. The alkyl group includes a straight chain alkyl group such as methyl, ethyl, n-propyl and n-butyl, a branched alkyl group such as isopropyl, sec-butyl and tert-butyl, cyclopropyl and cyclopentyl. And cyclic alkyl groups such as cyclobutyl.

Examples of the alkenyl group include vinyl, allyl, propenyl, 1-butenyl, 2-butenyl and the like, and examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl and the like.

  Examples of the aromatic hydrocarbon group that may contain an oxygen atom or sulfur atom include phenyl, tolyl, naphthyl, anthracenyl and the like, and heterocyclic aromatic compound groups such as furanyl and thienyl.

In formula (6), two or more groups of R ^{6 to} R ⁹ may be bonded to each other to form a ring structure. Specific examples of the group formed by bonding two groups to each other include methylene, ethylene , Linear alkylene groups such as propylene and butylene, branched alkylene groups such as 1-methylethylene, 1,1-dimethylethylene and 1,2-dimethylethylene, 1,3-cyclopentylene, 1,4-cyclohexylene, And cyclic alkylene groups such as 1,2-cyclohexylene.

  Specific examples of the group formed by bonding three groups to each other include propane-1,2,3-triyl, 3- (ethyl-2-yl) pentane-1,5-diyl, and 3,3-bis (ethyl). 2-yl) pentan-1-yl and the like, and specific examples of groups in which four groups are bonded to each other include 4- (propyl-3-yl) heptane-1,4,7-triyl and the like. Is mentioned.

  Specific examples of preferred ammonium cations in formula (6) include n-propylammonium, n-butylammonium, cyclohexylammonium, triethylammonium, tributylammonium, tetramethylammonium, tetraethylammonium, trimethylethylammonium, triallylmethylammonium. , Phenyltrimethylammonium, dimethylpyrrolidinium, N-methyl-N-propylpyrrolidinium, dimethylmorpholinium, 1-methyl-1-azabicyclo [2.2.2] octanium, 1-methyl-1-azabicyclo [ 2.2.1] Heptanium, 7,7-dimethyl-7-azabicyclo [2.2.1] heptanium, 5-azoniaspiro [4.4] nonane, 5-azoniaspiro [4.5] decane, 1-methyl- 1 Azoniabicyclo [3.3.0] octane, 1-azoniatricyclo [3.3.3.0] undecane.

In formula (6), X ⁻ represents an anion, and the corresponding acid XH has a pKa of the acid HOP (O) corresponding to the counter anion [PO ₂ (OR ² ) (OR ³ )] ⁻ of the phosphate diester salt (G). ) (OR ² ) (OR ³ ) having a larger pKa. Here, pKa is as already described above.

Anion X as described above ^- as is monosubstituted carbonate anion, unsubstituted carbonate dianion, phosphodiester anion, phosphoric acid monoester anion, phosphate anion, carboxylate anion, phenolate anion, thiophenolate anion, thio Cyanate anions and the like are mentioned, and preferred specific examples are monomethyl carbonate anion, monoethyl carbonate anion, carbonate anion, phosphate anion, acetic acid, propionic acid, benzoic acid, salicylic acid and other carboxylic acid anions. More preferred are monomethyl carbonate anion, monoethyl carbonate anion, and carbonate anion.

In the reaction for obtaining the phosphoric acid diester salt (H), a solvent may be used as necessary. What was illustrated by reaction of phosphoric acid triester (A) and secondary amine (B) is used suitably as a solvent. The molar ratio of the ammonium salt (G) to be used is preferably 1 to 2 moles, more preferably 1 to 1.1 moles relative to the phosphoric acid diester salt (C).

  According to the production method of the present invention, the amidinium salt (J) represented by the following general formula (8) with respect to the phosphoric acid diester salt obtained by the reaction of the phosphoric acid triester (A) and the secondary amine (B). Can be further reacted to produce the phosphoric acid diester salt (K) represented by the general formula (9).

In the formula (8), R ^{10 to} R ¹³ may be the same or different and each represents a hydrocarbon group having 1 to 20 carbon atoms, ¹⁴ is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, R Groups on two of ^{10 to} R ¹⁴ may be bonded to each other to form a ring structure, and RX ⁻ represents an anion.

In formula (9), R ^{2 to} R ³ are the same as in general formula (1), and R ^{10 to} R ¹⁴ are the same as in general formula (8).

As a C1-C20 hydrocarbon group in R < ¹⁰ > -R < ¹⁴ > in Formula (8), the aromatic hydrocarbon group which may contain the alkyl group, the alkenyl group, the alkynyl group, the oxygen atom, or the sulfur atom Examples of the alkyl group include linear alkyl groups such as methyl, ethyl, n-propyl, and n-butyl, branched alkyl groups such as isopropyl, sec-butyl, and tert-butyl, cyclopropyl, cyclopentyl, cyclobutyl, and the like. Examples thereof include a cyclic alkyl group.

Examples of the alkenyl group include vinyl, allyl, propenyl, 1-butenyl, 2-butenyl and the like, and examples of the alkynyl group include ethynyl, 1-propynyl, 2-propynyl and the like.

  Examples of the aromatic hydrocarbon group which may contain an oxygen atom or a sulfur atom include heterocyclic aromatic compound groups such as phenyl, tolyl, naphthyl, anthracenyl and the like, as well as furanyl and thienyl.

In Formula (8), two or more groups of R ^{10 to} R ¹⁴ may be bonded to each other to form a ring structure. Specific examples of the group formed by bonding two groups to each other include a methylene group, Linear alkylene group such as ethylene group, propylene group and butylene group, branched alkylene group such as 1-methylethylene group, 1,1-dimethylethylene group and 1,2-dimethylethylene group, 1,3-cyclopentylene group And cyclic alkylene groups such as 1,4-cyclohexylene group and 1,2-cyclohexylene group.

  Specific examples of the group formed by bonding three groups to each other include propane-1,2,3-triyl, 3- (ethyl-2-yl) pentane-1,5-diyl, and 3,3-bis (ethyl). -2-yl) pentan-1-yl and the like.

Specific examples of preferred ammonium cations in the formula (8) include 8-methyl-1,8-diazabicyclo [5.4.0] -7-undecenium, 5-methyl-1,5-diazabicyclo [4.3.0. ] -5-nonenium, 1,2,3,4-tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, 4-cyano-1,2,3-trimethylimidazolinium, 4-acetyl-1,2,3-trimethylimidazolinium, 4-methoxy-1,2,3-trimethylimidazolinium, 4-hydroxymethyl-1,2,3-trimethylimidazolinium, 1,3- Dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1,2,3-trimethylimidazolium, 1,2,3,4 Tetramethylimidazolium, 4-cyano-1,2,3-trimethylimidazolium, 4-acetyl-1,2,3-trimethylimidazolium, 4-methoxy-1,2,3-trimethylimidazolium, 4-hydroxy Methyl-1,2,3-trimethylimidazolium, 2,3-dimethyl-1,3-diazabicyclo [4.2.1] -2-nonenium, 2,3-dimethyl-1,3-diazabicyclo [2.2 .1] -2-heptenium and the like.

In formula (8), X ⁻ represents an anion, and the corresponding acid XH has a pKa of the acid HOP (O corresponding to the counter anion [PO ₂ (OR ² ) (OR ³ )] ⁻ of the phosphate diester salt (J). ) (OR ² ) (OR ³ ) having a larger pKa. Here, pKa is as described above, and specific examples of the anion X ⁻ are as described above.

Since the phosphoric acid diester salt obtained in the present invention is highly pure and substantially free of impurities, it is suitably used for electronic materials that do not like mixing of organic impurities and ionic impurities. For example, it can be used as an electrolyte added to various batteries including aluminum electrolytic capacitors, electric double layer capacitors, and Li-ion batteries. The phosphoric acid diester salt is particularly useful for an electrolytic solution for an aluminum electrolytic capacitor.

The electrolytic solution for an aluminum electrolytic capacitor is produced by dissolving the phosphoric diester salt obtained in the present invention in an organic solvent, and in combination with an electrolyte conventionally used for an electrolytic solution for an aluminum electrolytic capacitor, if necessary. An agent can also be added.

  As the organic solvent, those used for aluminum electrolytic capacitors can be suitably used without particular limitation.

  Specific examples include methanol, ethanol, alcohols such as ethylene glycol, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethers such as ethylene glycol diethyl ether, amides such as N-methylformamide, N, N-dimethylformamide, γ -Butyrolactone, δ-valerolactone, lactones such as β-butyrolactone, nitriles such as acetonitrile and propionitrile, carbonates such as ethylene carbonate and propylene carbonate, sulfones such as sulfolane and dimethylsulfone, etc., and one organic solvent Or two or more kinds may be used in combination.

  The content of the phosphoric acid diester salt obtained in the present invention is preferably 5 to 70% by weight, particularly preferably 10 based on the weight of the electrolyte and the organic solvent from the viewpoint of specific conductivity and from the viewpoint of the organic solvent. -40% by weight.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

Production Example 1
Method for Producing 1,2,3,4-Tetramethylimidazolinium Methyl Carbonate Methanol Solution In a pressure vessel equipped with a stirrer, 180 parts of dimethyl carbonate (manufactured by Tokyo Chemical Industry) and 63 parts of methanol are charged, and 2,4-dimethyl is added thereto. 98 parts of imidazoline was dropped and stirred at 120 ° C. for 15 hours to obtain a methanol solution of 1,2,3,4-tetramethylimidazolinium methyl carbonate (J-1).

Example 1
Synthesis of 1,2,3,4-tetramethylimidazolinium diethyl phosphate (K-1) In a pressure vessel equipped with a stirrer, 162 parts of triethyl phosphate (manufactured by Nippon Synthetic Chemical) (A-1) (0.89 Mol) and 130 parts (1.78 mol) of diethylamine (BASF) (B-1) were charged and the temperature was raised to 125 ° C. The reaction was allowed to proceed with stirring for 30 hours. When the reaction mixture was cooled and P-NMR was measured, the triethyl phosphate peak disappeared and only the diethyl phosphate peak appeared. To this reaction liquid, 260 parts (0.9 mol) of a methanol solution of 1,2,3,4-tetramethylimidazolinium methyl carbonate (J-1) was added for salt exchange. This solution was concentrated under reduced pressure at 100 ° C. using a rotary evaporator to obtain a tan solid. It was confirmed by H-NMR and P-NMR that the tan solid was 1,2,3,4-tetramethylimidazolinium diethylphosphate (K-1).

Example 2 Synthesis of diethylammonium diethylphosphate (C-1) In a pressure vessel equipped with a stirrer, triethyl phosphate (manufactured by Nippon Gosei Kagaku) (A-1) 162 parts (0.89 mol), diethylamine (manufactured by BASF) (B-1) 130 parts (1.78 mol) was charged and the temperature was raised to 125 ° C. The reaction was allowed to proceed with stirring for 30 hours. When the reaction mixture was cooled and P-NMR was measured, the triethyl phosphate peak disappeared and only the diethyl phosphate peak appeared. The reaction solution was concentrated under reduced pressure at 100 ° C. using a rotary evaporator to obtain a brown liquid. It was confirmed by H-NMR and P-NMR that the brown liquid was diethylammonium diethylphosphate (C-1).

Example 3 Synthesis of triethylammonium diethyl phosphate (D-1) In Example 2, the same operation as in Example 2 was performed, except that 130 parts of diethylamine (manufactured by BASF) was changed to 65 parts (0.89 mol). A tan liquid was obtained. It was confirmed by H-NMR and P-NMR that the tan solid was triethylammonium diethyl phosphate (C-2).

Example 4 Synthesis of 1,5-diazabicyclo [4.3.0] -5-nonenium diethyl phosphate (F-1) In Example 1, 1,2,3,4-tetramethylimidazolinium methyl carbonate Example 1 except that 260 parts of salt methanol solution was changed to 112 parts (0.9 mol) of 1,5-diazabicyclo [4.3.0] -5-nonene (San Apro) (E-1). Operation was performed to obtain a tan liquid. It was confirmed by H-NMR and P-NMR that the tan solid was 1,5-diazabicyclo [4.3.0] -5-nonenium diethyl phosphate (F-1).

Example 5 Synthesis of pyrrolidinium diethyl phosphate (C-2) In Example 2, 130 parts of diethylamine (manufactured by BASF) was changed to 127 parts (1.78 mol) of pyrrolidine (manufactured by Tokyo Chemical Industry) (B-2). Except for the above, the same operation as in Example 2 was performed to obtain a tan liquid. It was confirmed by H-NMR and P-NMR that the tan solid was pyrrolidinium diethyl phosphate (C-2).

Example 6 Synthesis of 1,2,3,4-tetramethylimidazolinium dibutyl phosphate (K-2) In Example 1, 162 parts of triethyl phosphate (manufactured by Nippon Gosei Kagaku) was added to tributyl phosphate (manufactured by Aldrich). (A-2) 266 parts (0.89 mol), and the reaction time was changed from 30 hours to 70 hours, the same operation as in Example 1 was performed to obtain a tan liquid. It was confirmed by H-NMR and P-NMR that the tan solid was 1,2,3,4-tetramethylimidazolinium dibutyl phosphate (K-2).

Production Example 2
Method for Producing Ethyltrimethylammonium Methyl Carbonate Methanol Solution In a pressure-resistant vessel equipped with a stirrer, 100 parts of dimethyl carbonate (manufactured by Tokyo Chemical Industry) and 100 parts of methanol are charged, and 73 parts of dimethyl ethylamine (manufactured by Tokyo Chemical Industry Co., Ltd.) is added dropwise to 120 ° C. For 8 hours to obtain a methanol solution of ethyltrimethylammonium methyl carbonate (G-1).

Example 7 Synthesis of ethyl trimethylammonium diethyl phosphate (H-1) In Example 1, 260 parts of 1,2,3,4-tetramethylimidazolinium methyl carbonate salt methanol solution was added to ethyl trimethyl ammonium methyl carbonate salt methanol solution. (G-1) A tan liquid was obtained in the same manner as in Example 1 except that 250 parts (0.9 mol) was used. It was confirmed by H-NMR and P-NMR that this tan solid was ethyltrimethylammonium diethylphosphate (H-1).

Comparative Production Example Synthesis of diethyl phosphate In a four-necked flask equipped with a stirrer and a reflux tube, 180 parts of triethyl phosphate (manufactured by Nippon Gosei Kagaku), 142 parts of a 30% aqueous sodium hydroxide solution, diethyl phosphate (manufactured by Tokyo Chemical Industry) 4 parts were charged and the temperature was raised to 80 ° C. over 1 hour. Furthermore, it stirred at 100 degreeC for 3 hours. The reaction solution was cooled to 60 ° C., 151 parts of a 36.6% aqueous sulfuric acid solution was added, and the mixture was stirred at 60 ° C. for 1 hour. After standing, the aqueous phase was removed. The organic phase was washed with water and then concentrated with an evaporator to obtain a transparent liquid.

Comparative Example 1 Synthesis of 1,2,3,4-tetramethylimidazolinium diethylphosphate (a-1) Into 137 parts of diethyl phosphate prepared in Comparative Production Example, 1,2,3,4-tetramethylimidazoli Salt exchange was performed by adding 260 parts of a nitromethyl carbonate methanol solution. This solution was concentrated under reduced pressure at 100 ° C. using a rotary evaporator to obtain a tan solid. It was confirmed by H-NMR and P-NMR that the tan solid was 1,2,3,4-tetramethylimidazolinium diethylphosphate (a-1).

  Phosphate diester salts (K-1), (C-1), (D-1), (F-1), (C-2), (K-2) of the present invention prepared in Examples 1 to 7 , (H-1) and phosphoric acid diester salt (a-1) for comparison prepared in Comparative Example 1, the phosphoric acid content, phosphoric acid monoester content, alkali metal content and sulfate ion content It measured by the method shown below. The results are shown in Table 1.

NMR measurement: Measured with a JEOL AL-300 superconducting nuclear magnetic resonance measuring apparatus. In P-NMR, samples were prepared by the following method.
Sample preparation: To a 5 mm diameter NMR tube, 30 mg of a sample, 0.3 mL of deuterated methanol, and 0.1 mL of triethylamine were added.
Chemical shift of phosphoric acid diester: -2 to -3PPM, quintet

Phosphoric acid monoester content in the anion: The phosphoric acid monoester content in the anion was measured by P-NMR measurement. It was identified by the integration ratio with phosphoric acid diester. The detection limit is 0.1 mol% or less.
Phosphoric acid monoester chemical shift around 3-0PPM, triplet

Phosphate anion content in anion: The phosphate anion content in the anion was measured by P-NMR measurement. It was identified by the integration ratio with phosphoric acid diester. The detection limit is 0.1 mol% or less.
Phosphate anion chemical shift near 0PPM, singlet

  Alkali metal content: The alkali metal content was measured by flameless atomic absorption spectrometry using an atomic absorption spectrophotometer (AA-6700F manufactured by Shimadzu Corporation). The measurement was performed by dissolving 1.0 part of phosphoric diester salt in 10 mL with methanol (reagent for trace metal analysis). The detection limit is 0.1 ppm or less.

  Sulfate ion content: sulfuric acid turbidimetric method: The sulfate ion content was measured based on JISK-1527. The detection limit is 1 ppm or less.

As is apparent from Table 1, according to the present invention, no metal salt or water is used in the production process, so there is almost no contamination of ionic impurities or impurities due to hydrolysis. Obtained with high purity.

  Phosphate diester salts (K-1), (C-1), (D-1), (F-1), (C-2), (K-2) of the present invention prepared in Examples 1 to 7 (H-1) and the phosphoric acid diester salt (a-1) for comparison prepared in Comparative Example 1 were used to make an electrolytic solution, and the specific conductivity and spark voltage were evaluated by the following methods. . The results are shown in Table 2.

  Electrolytic solution preparation method: 25 parts of phosphoric acid diester salt was dissolved in 75 parts of γ-butyrolactone (manufactured by Mitsubishi Chemical) to obtain an electrolytic solution.

  Specific conductivity: Specific conductivity at 30 ° C. was measured using a conductivity meter CM-40S manufactured by Toa Denpa Kogyo Co., Ltd.

  Spark voltage: A 10 cm 2 high pressure chemical etching aluminum foil was used for the anode and a 10 cm 2 plain aluminum foil was used for the cathode, and the discharge voltage of the electrolyte was measured when a constant current method (2 mA) was applied at 25 ° C.

  As is clear from Table 2, in Examples 1 to 7, no discoloration due to corrosion of the foil that was thought to be derived from ionic impurities was not observed. In addition, an electrolytic solution using 1,2,3,4-tetramethylimidazolinium diethyl phosphate (Example 1) obtained by the production method of the present invention and 1,2,3 obtained by a conventional production method. , 4-tetramethylimidazolinium diethyl phosphate (Comparative Example 1) has the same specific conductivity and spark voltage.

  Since the phosphoric diester obtained by the production method of the present invention does not substantially contain impurities, it is useful as an electrolyte for electrolytic solutions including capacitors. It is also useful in electrical and electronic applications such as battery additives.

Claims (3)

The phosphoric acid triester (A) represented by the general formula (1) and the secondary amine (B) represented by the general formula (2) are reacted in the absence of water, and 1 mol of (A) ( B) When 1 mol is reacted, the phosphoric acid diester salt (C) represented by the general formula (3) is obtained, and (A) 1 mol and (B) more than 1 mol and less than 2 mol are reacted. In this case, a mixture of the phosphoric acid diester salt (D) represented by the general formula (4) and the phosphoric acid diester salt (C) is obtained, and the obtained phosphoric acid diester salt (C) or the above mixture is obtained. In general, the pKa of the corresponding acid XH of the counter anion X ⁻ has a larger pKa than the corresponding acid HOP (O) (OR ² ) (OR ³ ) of the counter anion [PO ₂ (OR ² ) (OR ³ )] ⁻ The amidinium salt (J) represented by the formula (8) is reacted to be represented by the general formula (9) Method for producing Berlin diester salt to give the phosphoric acid diester salt (K).

[To display the hydrocarbon radical of the formula (1) ^in, R 1 to R ³ to 20 carbon atoms which may be the same or different. ]

[In formula (2), R ^{4 to} R ⁵ represent a hydrocarbon group having 1 to 20 carbon atoms which may be the same or different. R ⁴ and R ⁵ may be bonded to each other to form a ring structure. ]

Wherein ^(3), R 1 ~R 3 is the same as the general formula ^(1), R 4 ~R ⁵ are the same as in the formula (2). ]

Wherein ^(4), R 2 to R ³ are the same as the general formula ^(1), R 4 ~R ⁵ are the same as in the formula (2). ]

[In formula (8), R ^{10 to} R ¹³ may be the same or different, and are hydrocarbons having 1 to 20 carbon atoms.
A ^{group, R 14} is a hydrogen atom, a hydrocarbon group having 1 to 20 carbon ^atoms, of R 10 ^{to R 14}
Two or more groups may be bonded to each other to form a ring structure, and X ⁻ represents an anion. ]

[In formula (9), R ^{2 to} R ³ are the same as in general formula (1), and R ^{10 to} R ¹⁴ are the same as in general formula (8). ] The method for producing a phosphoric acid diester salt according to claim ¹ , wherein R ^{1 to} R ^{3 in} the general formula (1) are all the same. A method for producing an electrolytic solution for an aluminum electrolytic capacitor, wherein the method according to claim 1 or 2 is performed and the obtained phosphoric acid diester salt is dissolved in an organic solvent.