JP6495041B2 - Method for producing alkali metal dihalophosphate and method for producing alkali metal difluorophosphate - Google Patents

Description

  The present invention relates to a method for producing an alkali metal dihalophosphate and a method for producing an alkali metal difluorophosphate. More specifically, the present invention relates to a method for producing an alkali metal dihalophosphate and a method for producing an alkali metal difluorophosphate that enable highly simple and highly efficient production by reaction between an alkali metal hydroxide and a phosphoryl halide.

  Conventionally, as a method for producing an alkali metal dihalophosphate excluding an alkali metal difluorophosphate, for example, there is a method for producing lithium dichlorophosphate by reacting phosphorus oxychloride with lithium carbonate (Patent Document 1 below). reference). According to this production method, it is possible to produce lithium dichlorophosphate efficiently and simply.

  However, in the production method of Patent Document 1, since the reactivity between phosphorus oxychloride and lithium carbonate is slow, a heating and reflux operation of at least about 90 ° C. is required to increase the reactivity. In addition, it takes a long time to complete the reaction. Furthermore, in the manufacturing method of Patent Document 1, since lithium chloride is generated as a byproduct of the reaction, an operation for separating it by filtration after the reaction is required. Further, since the product lithium dichlorophosphate is poorly soluble in an organic solvent, a large amount of reaction solvent is required to completely dissolve the produced lithium dichlorophosphate. Furthermore, in order to separate lithium dichlorophosphate from the reaction filtrate, it is necessary to distill off a large amount of the reaction solvent by an operation such as vacuum drying or heat drying, which is not preferable from the viewpoint of energy consumption and safety. .

  Patent Document 1 also discloses a method for producing lithium difluorophosphate by reacting lithium dichlorophosphate obtained by the reaction of phosphorus oxychloride and lithium carbonate with hydrogen fluoride. .

  However, since hydrogen fluoride is highly reactive, it causes a substitution reaction with oxygen in addition to the substitution reaction of lithium dichlorophosphate with chlorine. As a result, there is a problem that lithium hexafluorophosphate and lithium fluoride are by-produced. It is not preferable from the viewpoint of reaction efficiency that hydrogen fluoride is excessively consumed by the production of by-products other than the target lithium difluorophosphate. Even if a mixture of lithium hexafluorophosphate or lithium fluoride may be obtained, it is difficult to control the production ratio of lithium difluorophosphate and by-products, requiring complicated operations.

JP 2014-15343

  The present invention has been made in view of the above-mentioned problems, and its object is to produce a dihalophosphate alkali metal salt and a difluorophosphate alkali metal salt that can be efficiently produced by a very simple method. Is to provide.

In order to solve the above-mentioned problems, the method for producing an alkali metal dihalophosphate of the present invention comprises an alkali metal hydroxide represented by MOH (wherein M represents an alkali metal atom), POX ₃ ( In the formula, X represents a halogen atom other than fluorine.) By reacting with a halogenated phosphoryl represented by MPO ₂ X ₂ (wherein M and X are as defined above). It is characterized by producing an alkali metal dihalophosphate represented.

  Moreover, in the said structure, reaction of the alkali metal hydroxide represented by the said MOH and the halogenated phosphoryl represented by the said POX3 can be performed in an organic solvent.

  In the above configuration, the reaction between the alkali metal hydroxide represented by MOH and the halogenated phosphoryl represented by POX3 can be carried out in the absence of a solvent.

  In the above configuration, the M is preferably a lithium atom.

  Furthermore, in the said structure, it is preferable that said X is a chlorine atom.

  Moreover, in order to solve the said subject, the manufacturing method of the alkali metal difluorophosphate of this invention is the alkali dihalophosphate represented by said MPO2X2 obtained by the manufacturing method of the alkali metal dihalophosphate described above. A metal salt is characterized by reacting with a fluoride salt of a monovalent or divalent cation in another organic solvent and fluorinated.

According to the method for producing an alkali metal dihalophosphate of the present invention, an alkali metal hydroxide (MOH (wherein M represents an alkali metal atom)) and a phosphoryl halide (POX ₃ (wherein X is A halogen atom other than a fluorine atom))) is reacted with an alkali metal dihalophosphate (MPO ₂ X ₂ (wherein M and X are as defined above)) simply and efficiently. It is possible to generate well.

Further, according to the method for producing an alkali metal difluorophosphate of the present invention, the alkali metal dihalophosphate (MPO ₂ X ₂ ) obtained by the method for producing an alkali metal dihalophosphate is converted to a monovalent or divalent cation. By reacting the fluoride salt in another organic solvent and fluorinating it, it becomes possible to easily and efficiently produce an alkali metal difluorophosphate.

(Method for producing alkali metal dihalophosphate)
A method for producing the alkali metal dihalophosphate according to the present embodiment will be described below.
The production method of the alkali metal dihalophosphate (MPO ₂ X ₂ (wherein M represents an alkali metal atom and X represents a halogen atom other than fluorine)) of the present embodiment includes an alkali metal hydroxide, This is done by reacting with a phosphoryl halide.

  The alkali metal hydroxide is represented by MOH (wherein M represents an alkali metal atom). The M is an alkali metal atom, and specifically includes at least one selected from the group consisting of Li, Na, K, Rb and Cs. From the viewpoint of high reactivity with the phosphoryl halide, the M is preferably Li. X is a halogen atom other than fluorine, and is specifically at least one selected from the group consisting of chlorine, bromine and iodine.

The halogenated phosphoryl is represented by POX ₃ (wherein X represents a halogen atom other than fluorine). More specifically, examples include phosphoryl chloride, phosphoryl bromide, phosphoryl iodide, and the like. These can be used alone or in combination of two or more. Of these phosphoryl halides, phosphoryl chloride is preferable from the viewpoint of availability and high reactivity with alkali metal hydroxides.

  The reaction start temperature when the alkali metal hydroxide and the phosphoryl halide start the reaction is not particularly limited as long as the reaction proceeds, but is in the range of −20 ° C. to 100 ° C., preferably 0 ° C. It is -25 degreeC, More preferably, it is 10 degreeC-less than 25 degreeC. By setting the reaction start temperature to 100 ° C. or lower, it is possible to suppress a decrease in yield due to the evaporation of phosphoryl halide and to prevent the purity of the alkali metal dihalophosphate from being lowered. On the other hand, by setting the reaction start temperature to −20 ° C. or higher, it is possible to prevent the phosphoryl halide from solidifying. The temperature adjusting means is not particularly limited, and when the reaction start temperature is cooled and controlled so as to be within the above temperature range, the reaction vessel in which the alkali metal hydroxide and the phosphoryl halide are charged is iced. It can be performed by cooling or the like. Moreover, when heating and controlling so that reaction start temperature may be in the said temperature range, it can carry out by the hot water bath etc. which were set to arbitrary temperature. In addition, after completion | finish of reaction of the said alkali metal hydroxide and halogenated phosphoryl, it falls to about room temperature (for example, 25 degreeC).

  The reaction between the alkali metal hydroxide and the phosphoryl halide may be performed in an organic solvent or in the absence of a solvent. The organic solvent is not particularly limited, but an aprotic organic solvent is preferable. By not using a protic organic solvent such as alcohol, side reactions such as generation of an alkoxyphosphoryl group or a phenoxyphosphoryl group can be suppressed.

  The aprotic organic solvent is not particularly limited, and examples thereof include nitriles, esters, ketones, ethers, and halogenated hydrocarbons. These can be used alone or in combination of two or more.

  The nitriles are not particularly limited, and examples thereof include acetonitrile and propionitryl. These can be used alone or in combination of two or more.

  The esters are not particularly limited, and examples thereof include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, ethyl acetate, methyl acetate, and butyl acetate. These can be used alone or in combination of two or more.

  The ketones are not particularly limited, and examples thereof include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These can be used alone or in combination of two or more.

  The ethers are not particularly limited, and examples thereof include diethyl ether, tetrahydrofuran, dimethoxyethane and the like. These can be used alone or in combination of two or more.

  The halogenated hydrocarbon is not particularly limited, and examples thereof include dichloromethane and chloroform. These can be used alone or in combination of two or more.

  Other examples of the aprotic solvent include nitromethane, nitroethane, dimethylformamide and the like. These can be used alone or in combination.

  As the usage-amount of the said organic solvent, 2 times or more amount is preferable with respect to the mass of the said alkali metal hydroxide, 2-10 times amount is more preferable, 4-5 times amount is especially preferable. By making the amount of the organic solvent used more than twice the mass of the alkali metal hydroxide, the stirrability of the alkali metal hydroxide during the reaction between the alkali metal hydroxide and the phosphoryl halide can be improved. Deterioration can be prevented and a decrease in reactivity can be suppressed. The upper limit of the amount of the organic solvent used is not particularly limited. However, if the organic solvent is used excessively, more energy than necessary is required for distilling it off, which may be industrially disadvantageous. . Accordingly, the upper limit of the amount of the organic solvent used is preferably set as appropriate according to the reaction species.

  The amount of phosphoryl halide used when synthesizing the alkali metal dihalophosphate in the organic solvent is preferably 1 equivalent or more, more preferably 1 to 2 equivalents, more preferably 1 equivalent of alkali metal hydroxide. Preferably it is 1.05-1.5 equivalent, Most preferably, it is 1.1-1.2 equivalent. By making the usage-amount of the said phosphoryl halide 1 equivalent or more, it can prevent that an alkali metal hydroxide remains. Although the upper limit is not particularly specified, when 2 or more equivalents of phosphoryl halide are used, excessive energy may be required when distilling off excess phosphoryl halide. Accordingly, the upper limit of the amount of the organic solvent used is preferably set as appropriate according to the reaction species. The “equivalent” means a molar equivalent. The molar equivalent represents the ratio of the substance amount (unit: mol [mol]).

  In addition, when synthesizing the alkali metal dihalophosphate in the organic solvent, the order of addition of each raw material is not particularly limited, but usually, after adding the alkali metal hydroxide to the reaction vessel, the organic solvent and the halogen This is done by sequentially adding phosphoryl chloride.

  Further, as described above, the reaction between the alkali metal hydroxide and the phosphoryl halide can also be performed in the absence of a solvent. In this case, phosphoryl halide also serves as a reaction solvent.

  When the alkali metal hydroxide and phosphoryl halide are reacted in the absence of a solvent, the amount of the phosphoryl halide used is preferably 1.5 equivalents or more, more preferably 1 equivalent of alkali metal hydroxide. 1.5 to 20 equivalents, more preferably 1.8 to 10 equivalents, particularly preferably 2 to 5 equivalents. By making the usage-amount of the said halogenated phosphoryl 1.5 equivalent or more, it can prevent that an alkali metal hydroxide remains. The upper limit of the amount of phosphoryl halide used is not particularly limited because the halogenated phosphoryl plays a role as a solvent in addition to a role as a reactive species. However, if phosphoryl halide is used in excess, more energy is required when distilling it off, which may be industrially disadvantageous. Therefore, the upper limit of the amount of phosphoryl halide used is preferably set as appropriate according to the reaction species. In addition, "equivalent" here means molar equivalent similarly to the above-mentioned case.

  In addition, when synthesizing an alkali metal dihalophosphate in the absence of a solvent, the order of addition of each raw material is not particularly limited, but usually, after adding phosphoryl halide serving as a solvent to the reaction vessel, It is carried out by adding a metal hydroxide.

  The reaction between the alkali metal hydroxide and the halogenated phosphoryl is preferably carried out in an inert gas such as nitrogen or argon or in a gas stream. Thereby, it can prevent that the water | moisture content in air | atmosphere melt | dissolves in a dihalophosphate alkali metal salt, and a composition change arises. In addition, when the alkali metal hydroxide is reacted with the phosphoryl halide, a mixing operation such as stirring, vibration, or rocking may be performed.

  As described above, according to the method for producing an alkali metal dihalophosphate of the present embodiment, the alkali metal dihalophosphate can be produced very simply and with high efficiency. The obtained dihalophosphate alkali metal salt can be used as a suitable precursor for producing difluorophosphate, phosphate diester and phosphate diester salt, and as a result, an electronic material such as an electrolyte of a lithium ion secondary battery. It can be used in a wide range of fields such as uses, cleaning agents, fiber treatment agents, emulsifiers, rust inhibitors, and pharmaceutical intermediates.

(Method for producing alkali metal difluorophosphate)
The dihalophosphate alkali metal salt obtained by the method for producing a dihalophosphate alkali metal salt can be used as a starting material for producing the difluorophosphate alkali metal salt.

  The alkali metal difluorophosphate can be produced by reacting the alkali metal dihalophosphate with a fluoride salt of a monovalent or divalent cation in another organic solvent to fluorinate it.

  The monovalent or divalent cation fluoride salt means, for example, an alkali metal, alkaline earth metal, transition metal or onium fluoride salt. These can be used alone or in combination of two or more.

The anion constituting the fluoride salt is not particularly limited. For example, fluoride ions (F ⁻ ), acidic fluoride ions (F (HF) ⁻ ), polyfluoride ions (F (HF) n ⁻ (where, n is a natural number of 1 to 10.)) and the like. These anions form various fluorides and fluoride salts according to the combination with the cation species to be paired and the reaction conditions when fluorination is performed, and the alkali metal difluorophosphate of the present embodiment It becomes possible to use for a manufacturing method.

  The alkali metal is not particularly limited, and examples thereof include lithium, sodium, potassium, rubidium, and cesium. These can be used alone or in combination of two or more. From the viewpoint of reactivity, potassium, rubidium, and cesium are preferable, and potassium is particularly preferable in consideration of economics such as manufacturing cost.

  The alkaline earth metal is not particularly limited, and examples thereof include magnesium, calcium, strontium, barium and the like. These can be used alone or in combination of two or more.

  It does not specifically limit as said transition metal, For example, manganese, cobalt, nickel, iron, chromium, copper, molybdenum, tungsten, vanadium etc. are mentioned. These can be used alone or in combination of two or more.

  The onium constituting the fluoride salt is not particularly limited, and examples thereof include ammonium, primary amine, secondary amine, tertiary amine proton adduct, and quaternary ammonium. These can be used alone or in combination of two or more.

  The primary amine is not particularly limited, and examples thereof include methylamine, ethylamine, propylamine and the like. These can be used alone or in combination of two or more.

  The secondary amine is not particularly limited, and examples thereof include dimethylamine, diethylamine, dipropylamine, dibutylamine, dipisopropylamine, diisobutylamine, and diethanolamine. These can be used alone or in combination of two or more. Of these secondary amines, diethylamine is preferred from the viewpoint of ease of handling.

  The tertiary amine is not particularly limited, and examples thereof include trimethylamine, triethylamine, tripropylamine, tributylamine, triethanolamine, N, N-diethylmethylamine, N, N-ethyldimethylamine and the like. These can be used alone or in combination of two or more. Of these tertiary amines, triethylamine is preferred from the viewpoints of availability and ease of handling.

  Examples of the quaternary ammonium include tetraethylammonium, tetrapropylammonium, tetraisopropylammonium, trimethylethylammonium, dimethyldiethylammonium, methyltriethylammonium, trimethylpropylammonium, trimethylisopropylammonium, tetrabutylammonium, trimethylbutylammonium, and trimethylpentylammonium. And trimethylhexylammonium. These can be used alone or in combination of two or more. Of these quaternary ammoniums, tetrabutylammonium is preferable from the viewpoint of easy availability and handling.

  The other organic solvent is not particularly limited, but an aprotic organic solvent is preferably used from the viewpoint of suppression of side reactions and reactivity of the fluorination reaction. The aprotic organic solvent is not particularly limited, and examples thereof include nitriles, esters, ketones, ethers, and halogenated hydrocarbons. These can be used alone or in combination of two or more.

  The nitriles are not particularly limited, and examples thereof include acetonitrile and propionitryl. These can be used alone or in combination of two or more.

  The esters are not particularly limited, and examples thereof include dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, ethyl acetate, methyl acetate, and butyl acetate. These can be used alone or in combination of two or more.

  The ketones are not particularly limited, and examples thereof include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. These can be used alone or in combination of two or more.

  The ethers are not particularly limited, and examples thereof include diethyl ether, tetrahydrofuran, dimethoxyethane and the like. These can be used alone or in combination of two or more.

  The halogenated hydrocarbon is not particularly limited, and examples thereof include dichloromethane and chloroform. These can be used alone or in combination of two or more.

  Other examples of the aprotic solvent include nitromethane, nitroethane, dimethylformamide and the like. These can be used alone or in combination.

  Of the aprotic organic solvents exemplified above, dimethoxyethane and acetonitrile are preferable from the viewpoint of the reactivity of the fluorination reaction, and dimethoxyethane is particularly preferable.

  The reaction temperature of fluorination is preferably 0 ° C to 100 ° C, more preferably 20 ° C to 100 ° C, and further preferably 25 ° C to 90 ° C from the viewpoint of reactivity. By setting the reaction temperature to 0 ° C. or higher, it is possible to suppress the precipitation of the product and to prevent the reaction from being inhibited. On the other hand, by setting the reaction temperature to 100 ° C. or less, the occurrence of side reactions can be suppressed, and economics such as production costs can be improved.

  The amount of the other organic solvent to be used is preferably 2 times or more, more preferably 2 to 20 times, particularly preferably 5 to 15 times the mass of the dihaloalkali metal salt. Stirability of the alkali metal dihalophosphate in the reaction of the alkali metal dihalophosphate and the fluoride salt by making the amount of the other organic solvent used more than twice the mass of the dihaloalkali metal salt. Deterioration of reactivity can be prevented, and a decrease in reactivity can be suppressed. Although the upper limit of the amount of the other organic solvent used is not particularly limited, excessive use of the other organic solvent requires more energy than necessary to distill it off, which is industrially disadvantageous. There is a case. Therefore, the upper limit of the amount of other organic solvent used is preferably set as appropriate according to the reaction species.

  The amount of the fluoride salt used when synthesizing the alkali metal difluorophosphate in the other organic solvent is preferably 2 to 10 equivalents relative to 1 equivalent of the alkali metal dihalophosphate, More preferably 2 to 5 equivalents, and particularly preferably 2 to 3 equivalents. By making the usage-amount of the said fluoride salt into 2 equivalent or more, generation | occurrence | production of the unreacted dihaloalkali metal salt can be suppressed. On the other hand, the energy for removing excess fluoride salt etc. can be suppressed by making the usage-amount of fluoride salt into 10 equivalents or less. In addition, "equivalent" here means molar equivalent similarly to the above-mentioned case.

  After the fluorination reaction, an alkali metal difluorophosphate can be obtained by appropriately combining operations such as filtration, drying, and extraction. The fluorination reaction is preferably carried out in an inert gas such as nitrogen or argon or in a gas stream. Thereby, it can prevent that the water | moisture content in air | atmosphere melt | dissolves in an alkali metal difluorophosphate, and a composition change arises. Furthermore, during the fluorination reaction, a mixing operation such as stirring, vibration, or rocking may be performed.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, materials, blending amounts, and the like described in the examples are not intended to limit the scope of the present invention only to those unless otherwise specified.

Example 1
25.0 g of dimethyl carbonate was charged into a flask equipped with a condenser and a dropping funnel, and then 5.0 g of lithium hydroxide was charged. Subsequently, 38.4 g of phosphoryl chloride was slowly added dropwise with stirring in the flask under a nitrogen atmosphere at 20 ° C. (reaction starting temperature). At this time, it was confirmed that the reaction was intense in the flask. In addition, phosphoryl chloride was 1.2 equivalents with respect to 1 equivalent of lithium hydroxide. Further, the amount of dimethyl carbonate was 5 times the mass 1 of lithium hydroxide.

  Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, dimethyl carbonate and excess phosphoryl chloride were distilled off at 130 ° C. under a nitrogen stream. As a result, 29.2 g of white crystals were obtained.

  This white crystal was subjected to anion chromatography (manufactured by Metrohm, trade name: IC-850), cation chromatography (manufactured by Dionex, trade name: ICS-1500), FT-IR (manufactured by PerkinElmer, trade name: SPECTRUM2000). , TG-DTA (manufactured by Seiko Instruments Inc., trade name: EXSTAR6000 TG / DTA6300).

As a result of the analysis by the cation chromatography, only Li ions were detected. As a result of analysis by anion chromatography, Cl ions and PO ₄ ions were detected. When the contents of Li, Cl, and P elements were determined from the respective ion concentrations, they were Li ions: 4.9%, Cl ions: 49.9%, and P elements: 21.9%. This value was very close to the content of each element of LiPO ₂ Cl ₂ (Li: 4.9%, Cl: 50.3%, P: 22.0%).

Moreover, when the infrared absorption spectrum was confirmed using FT-IR, the obtained compound confirmed absorption derived from O = PO bond in the vicinity of 1100 cm ⁻¹ . This suggested that the O═P—Cl skeleton of phosphoryl chloride was converted to an O═P—O skeleton.

  Furthermore, from the measurement result of TG-DTA, it was confirmed that the thermal decomposition temperature of the compound was 199 ° C. The boiling point of the raw material phosphoryl chloride is 105 ° C., and the decomposition point of lithium hydroxide is 924 ° C. Therefore, it was confirmed that the thermophysical property was different from the white crystal product.

  As a result of comprehensive judgment based on the above analysis results, it was determined that the obtained white crystalline solid was lithium dichlorophosphate. Moreover, the mass yield converted from the obtained white crystal solid lithium dichlorophosphate was 99.3% by mass.

(Example 2)
25.0 g of dimethyl carbonate was charged into a flask equipped with a condenser and a dropping funnel, and then 5.0 g of lithium hydroxide was charged. Subsequently, 38.4 g of phosphoryl chloride was slowly added dropwise with stirring in the flask under a nitrogen atmosphere at 100 ° C. (reaction start temperature). At this time, it was confirmed that the reaction was intense in the flask. In addition, phosphoryl chloride was 1.2 equivalents with respect to 1 equivalent of lithium hydroxide. Further, the amount of dimethyl carbonate was 5 times the mass 1 of lithium hydroxide.

  Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, dimethyl carbonate and excess phosphoryl chloride were distilled off at 130 ° C. under a nitrogen stream. As a result, 29.1 g of white crystals were obtained.

  This white crystal was subjected to anion chromatography (manufactured by Metrohm, trade name: IC-850), cation chromatography (manufactured by Dionex, trade name: ICS-1500), FT-IR (manufactured by PerkinElmer, trade name: SPECTRUM2000). , TG-DTA (manufactured by Seiko Instruments Inc., trade name: EXSTAR6000 TG / DTA6300).

As a result of the analysis by the cation chromatography, only Li ions were detected. As a result of analysis by anion chromatography, Cl ions and PO ₄ ions were detected. When the contents of Li, Cl, and P elements were determined from the respective ion concentrations, they were Li ions: 4.9%, Cl ions: 50.1%, and P elements: 22.1%. This value was very close to the content of each element of LiPO ₂ Cl ₂ (Li: 4.9%, Cl: 50.3%, P: 22.0%).

Moreover, when the infrared absorption spectrum was confirmed using FT-IR, the obtained compound confirmed absorption derived from O = PO bond in the vicinity of 1100 cm ⁻¹ . This suggested that the O═P—Cl skeleton of phosphoryl chloride was converted to an O═P—O skeleton.

  Furthermore, from the measurement result of TG-DTA, it was confirmed that the thermal decomposition temperature of the compound was 199 ° C. The boiling point of the raw material phosphoryl chloride is 105 ° C., and the decomposition point of lithium hydroxide is 924 ° C. Therefore, it was confirmed that the thermophysical property was different from the white crystal product.

  As a result of comprehensive judgment based on the above analysis results, it was determined that the obtained white crystalline solid was lithium dichlorophosphate. Moreover, the mass yield converted from the obtained white crystal solid lithium dichlorophosphate was 99.0% by mass.

(Example 3)
10 g of dimethyl carbonate was charged into a flask equipped with a condenser and a dropping funnel, and then 0.5 g of lithium hydroxide was charged. Subsequently, a solution prepared by dissolving 6.0 g of phosphoryl bromide in 20 g of dimethyl carbonate was slowly added dropwise while stirring the inside of the flask under a nitrogen atmosphere at 20 ° C. (reaction starting temperature). At this time, it was confirmed that the reaction was intense in the flask. In addition, phosphoryl bromide was 1.0 equivalent with respect to 1 equivalent of lithium hydroxide. Moreover, the amount of dimethyl carbonate was 20 times the mass 1 of lithium hydroxide.

  Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, dimethyl carbonate was distilled off at 130 ° C. under a nitrogen stream. As a result, 4.77 g of a white crystalline solid was obtained.

  The obtained white crystal was analyzed using FT-IR (Perkin Elmer, trade name: SPECTRUM2000), TG-DTA (Seiko Instruments, trade name: EXSTAR6000 TG / DTA6300).

When the infrared absorption spectrum was confirmed using said FT-IR, the obtained compound confirmed the absorption derived from O = PO bond in the vicinity of 1100 cm ⁻¹ . This suggested that the O = P-Br skeleton of phosphoryl bromide was converted to the O = PO skeleton. Moreover, the mass yield of the obtained crystal converted from lithium dibromophosphate was 99.5% by mass.

Example 4
30 g of dimethoxyethane was charged into the flask, and then 7.19 g of triethylamine and 2.9 g of anhydrous hydrofluoric acid were sequentially added to prepare triethylamine hydrofluoride in dimethoxyethane.

  Next, 5.0 g of lithium dichlorophosphate obtained in Example 1 was suspended in 20 g of dimethoxyethane. Further, this suspension was added dropwise to a triethylamine hydrofluoride / dimethoxyethane solution with stirring under a nitrogen atmosphere. The reaction temperature at this time was 25 degreeC, and stirring was performed for 3 hours. The reaction proceeded with a white precipitate.

  Next, the obtained white precipitate was separated from the filtrate by vacuum filtration. Further, the filtrate was distilled off under reduced pressure to obtain a white solid. This white solid was subjected to anion analysis using ion chromatography (trade name: ICS-1000, manufactured by Dionex). As a result, it was confirmed that the obtained white solid was lithium difluorophosphate. The relative area ratio of difluorophosphate ions was used as an indicator of the purity of lithium difluorophosphate. The purity of the obtained lithium difluorophosphate was 94.0% in relative area.

(Example 5)
48.1 g of phosphoryl chloride was added to a flask equipped with a condenser and a solid funnel, and 5.0 g of lithium hydroxide was added little by little under ice cooling. Subsequently, when the inside of the flask was stirred at 20 ° C. (reaction start temperature) under a nitrogen atmosphere, it was confirmed that the reaction was vigorous in the flask. In addition, phosphoryl chloride was 1.5 equivalent with respect to 1 equivalent of lithium hydroxide.

  Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, excess phosphoryl chloride was distilled off at 130 ° C. under a nitrogen stream. As a result, 29.0 g of white crystals were obtained.

As a result of the analysis by the cation chromatography, only Li ions were detected. As a result of analysis by anion chromatography, Cl ions and PO ₄ ions were detected. When the contents of Li, Cl and P elements were determined from the respective ion concentrations, they were Li ions: 4.9%, Cl ions: 50.1%, and P elements: 21.9%. This value was very close to the content of each element of LiPO ₂ Cl ₂ (Li: 4.9%, Cl: 50.3%, P: 22.0%).

Moreover, when the infrared absorption spectrum was confirmed using FT-IR, the obtained compound confirmed the absorption derived from O = PO bond in the vicinity of 1100 cm ⁻¹ . This suggested that the O═P—Cl skeleton of phosphoryl chloride was converted to an O═P—O skeleton.

  Furthermore, from the measurement result of TG-DTA, it was confirmed that the thermal decomposition temperature of the compound was 199 ° C. The boiling point of the raw material phosphoryl chloride is 105 ° C., and the decomposition point of lithium hydroxide is 924 ° C. Therefore, it was confirmed that the thermophysical property was different from the white crystal product.

  As a result of comprehensive judgment based on the above analysis results, it was determined that the obtained white crystalline solid was lithium dichlorophosphate. Moreover, the mass yield converted from the obtained white crystal solid lithium dichlorophosphate was 98.6% by mass.

(Example 6)
Into a flask equipped with a condenser and a solid funnel, 16.0 g of phosphoryl chloride was added, and 0.5 g of lithium hydroxide was added little by little under ice cooling. Subsequently, when the inside of the flask was stirred at 20 ° C. (reaction start temperature) under a nitrogen atmosphere, it was confirmed that the reaction was vigorous in the flask. In addition, phosphoryl chloride was 5 equivalents with respect to 1 equivalent of lithium hydroxide.

Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, excess phosphoryl chloride was distilled off at 130 ° C. under a nitrogen stream.
This gave 2.8 g of white crystals.

As a result of the analysis by the cation chromatography, only Li ions were detected. As a result of analysis by anion chromatography, Cl ions and PO ₄ ions were detected. When the contents of Li, Cl, and P elements were determined from the respective ion concentrations, they were Li ions: 4.9%, Cl ions: 49.7%, and P elements: 21.8%. This value was very close to the content of each element of LiPO ₂ Cl ₂ (Li: 4.9%, Cl: 50.3%, P: 22.0%).

Moreover, when the infrared absorption spectrum was confirmed using FT-IR, the obtained compound confirmed absorption derived from O = PO bond in the vicinity of 1100 cm ⁻¹ . This suggested that the O═P—Cl skeleton of phosphoryl chloride was converted to an O═PO skeleton.

  Furthermore, from the measurement result of TG-DTA, it was confirmed that the thermal decomposition temperature of the compound was 199 ° C. The boiling point of the raw material phosphoryl chloride is 105 ° C., and the decomposition point of lithium hydroxide is 924 ° C. Therefore, it was confirmed that the thermophysical property was different from the white crystal product.

  As a result of comprehensive judgment based on the above analysis results, it was determined that the obtained white crystalline solid was lithium dichlorophosphate. Moreover, the mass yield converted from the obtained white crystalline solid lithium phosphate was 96.6% by mass.

(Example 7)
64.0 g of phosphoryl chloride was added to a flask equipped with a condenser and a solid funnel, and 0.5 g of lithium hydroxide was added little by little under ice cooling. Subsequently, when the inside of the flask was stirred at 20 ° C. (reaction start temperature) under a nitrogen atmosphere, it was confirmed that the reaction was vigorous in the flask. In addition, phosphoryl chloride was 20 equivalents with respect to 1 equivalent of lithium hydroxide.

Thereafter, the inside of the flask was stirred for about 30 minutes. When the generation of gas almost subsided and cooled to room temperature, excess phosphoryl chloride was distilled off at 130 ° C. under a nitrogen stream.
As a result, 28.7 g of white crystals were obtained.

As a result of the analysis by the cation chromatography, only Li ions were detected. As a result of analysis by anion chromatography, Cl ions and PO ₄ ions were detected. When the contents of Li, Cl and P elements were determined from the respective ion concentrations, they were Li ions: 4.9%, Cl ions: 49.9%, and P elements: 21.6%. This value was very close to the content of each element of LiPO ₂ Cl ₂ (Li: 4.9%, Cl: 50.3%, P: 22.0%).

  As a result of comprehensive judgment based on the above analysis results, it was determined that the obtained white crystalline solid was lithium dichlorophosphate. Moreover, the mass yield converted from the obtained white crystal solid lithium dichlorophosphate was 97.6% by mass.

Claims (4)

An alkali metal hydroxide represented by MOH (wherein M represents an alkali metal atom) and phosphoryl halide represented by POX ₃ (wherein X represents a halogen atom other than fluorine); By reacting in an aprotic organic solvent or in the absence of a solvent ,
A method for producing an alkali metal dihalophosphate, wherein an alkali metal dihalophosphate represented by MPO ₂ X ₂ (wherein M and X are as defined above) is produced. The method for producing an alkali metal dihalophosphate according to claim 1 , wherein M is a lithium atom. The method for producing an alkali metal dihalophosphate according to claim 1 or 2 , wherein X is a chlorine atom. The dihalophosphate alkali metal salt represented by MPO ₂ X ₂ obtained by the method for producing an alkali metal dihalophosphate according to any one of claims 1 to 3 , is converted to a monovalent or divalent cation fluoride. A method for producing an alkali metal difluorophosphate that is reacted with a fluoride salt in another organic solvent to be fluorinated.