JP2011132072A - Method for producing lithium hexafluorophosphate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide lithium hexafluorophosphate at high yield by an efficient and simple method. <P>SOLUTION: This method for producing lithium hexafluorophosphate includes the steps that at least one kind of lithium salt selected from among lithium carboxylate, lithium carbonate and lithium hydrogencarbonate is brought into contact with an ammonium hexafluorophosphate compound. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing lithium hexafluorophosphate useful as, for example, a catalyst for organic synthesis reaction or a dopant for semiconductor materials.

Conventionally, as a method for producing lithium hexafluorophosphate, for example, the following methods are known.
(1) A method of reacting lithium halide and phosphorus pentachloride in the presence of hydrofluoric anhydride (see, for example, Patent Documents 1 and 2).
(2) A method of reacting lithium halide and phosphorus pentafluoride in an anhydrous hydrofluoric acid solvent (for example, see Non-Patent Document 1)
(3) A method of reacting a hydrogen fluoride adduct of porous lithium fluoride with gaseous phosphorus pentafluoride (see, for example, Patent Document 3).

JP 60-251109 A JP-A-5-279003 Japanese Patent Application Laid-Open No. 64-072901

J. et al. Chem. Soc. , 4408 (1963)

  However, since lithium hexafluorophosphate is a compound that is extremely hygroscopic and easily hydrolyzed, there has been a problem that the decomposition reaction cannot be avoided due to moisture mixed in the atmosphere or reaction raw materials. Further, the conventional method has a problem that it is necessary to use phosphorus pentachloride or phosphorus pentafluoride which is complicated to handle.

  An object of the present invention is to solve the above-mentioned problems and to provide lithium hexafluorophosphate with high yield by an efficient and simple method.

  An object of the present invention is to react at least one lithium salt selected from lithium carboxylate, lithium carbonate and lithium hydrogen carbonate with an ammonium hexafluorophosphate compound. This is solved by a method for producing lithium phosphate.

  INDUSTRIAL APPLICABILITY According to the present invention, a method for producing lithium hexafluorophosphate useful as a catalyst for organic synthesis reaction or a dopant for semiconductor materials can be provided.

  The lithium salt used in the reaction of the present invention is at least one lithium salt selected from lithium carboxylate, lithium carbonate and lithium bicarbonate, and examples of the lithium carboxylate include lithium formate, Although lithium acetate, lithium propionate, etc. are mentioned, Preferably lithium acetate and lithium carbonate are used. In addition, you may use these lithium salts individually or in mixture of 2 or more types.

  Examples of the ammonium hexafluorophosphate compound used in the reaction of the present invention include ammonium hexafluorophosphate; hexafluorophosphoric acid (monomethylammonium), hexafluorophosphoric acid (monoethylammonium), and hexafluoride. Hexafluorophosphoric acid (monohydrocarbyl ammonium) such as phosphoric acid (monobenzylammonium), hexafluorophosphoric acid (monophenethylammonium), hexafluorophosphoric acid (monoanilinium); hexafluorophosphoric acid (dimethylammonium) ), Hexafluorophosphoric acid (diethylammonium), hexafluorophosphoric acid (methylethylammonium, hexafluorophosphoric acid (benzylmethylammonium), hexafluorophosphoric acid (methylphenethylammonium), hexafluorophosphoric acid ( Hexafluorophosphoric acid (dihydro) such as N-methyl-N-phenylammonium) Rubyl ammonium); hexafluorophosphoric acid (trimethylammonium), hexafluorophosphoric acid (triethylammonium), hexafluorophosphoric acid (diisopropylethylammonium), hexafluorophosphoric acid (benzyldimethylammonium), phosphorus hexafluoride Hexafluorophosphoric acid (trihydrocarbyl ammonium) such as acid (N, N-dimethylphenylammonium); hexafluorophosphoric acid (tetramethylammonium), hexafluorophosphoric acid tetraethylammonium), hexafluorophosphoric acid (tetra Butyl ammonium) and hexafluorophosphoric acid (tetrahydrocarbyl ammonium) such as hexafluorophosphoric acid (benzyltrimethylammonium), and the like, preferably ammonium hexafluorophosphate is used. In addition, you may use these ammonium hexafluorophosphate compounds individually or in mixture of 2 or more types.

  The amount of the ammonium hexafluorophosphate compound to be used is preferably 0.2 to 5 mol, more preferably 0.5 to 2 mol, per 1 mol of the lithium salt.

  The reaction of the present invention is preferably carried out in the presence of a solvent, and the solvent used is not particularly limited as long as it does not inhibit the reaction. For example, nitriles such as acetonitrile and propionitrile; diethyl ether, tetrahydrofuran, ethers such as t-butyl methyl ether; carboxylic acids such as formic acid, acetic acid and propionic acid; esters such as methyl formate and ethyl acetate; lactones such as γ-butyrolactone; dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene Carbonates such as carbonate, vinylene carbonate, 4-fluoroethylene carbonate, propylene carbonate and diphenyl carbonate; sulfonic acids such as sulfuric acid and methanesulfonic acid are used.

  Although the usage-amount of the said solvent is suitably adjusted with the solubility of a reaction reagent or a product, Preferably it is 1-50g with respect to 1g of ammonium hexafluorophosphate compounds, More preferably, it is 2-25g.

  In the reaction of the present invention, at least one lithium salt selected from lithium carboxylate, lithium carbonate and lithium hydrogen carbonate, an ammonium hexafluorophosphate compound and a solvent are mixed and reacted while stirring, etc. It is done by the method. The reaction temperature at that time is preferably 0 to 200 ° C., more preferably 20 to 150 ° C., and the reaction pressure is not particularly limited.

  The lithium hexafluorophosphate obtained in the reaction of the present invention can be isolated and purified by a general method such as filtration, concentration, distillation, recrystallization, crystallization, column chromatography and the like after completion of the reaction. Depending on the usage form of lithium hexafluorophosphate, the reaction solution is appropriately treated as necessary, and then used as a solution of an organic solvent used in the production of lithium hexafluorophosphate (isolation / purification). It is also possible to use it for other purposes.

  The reaction of the present invention is represented, for example, by the following formula in the case of the reaction of Example 1 described later. The lithium hexafluorophosphate (target product) obtained by the reaction of the present invention is the raw material phosphorous hexafluoride. It is a high-purity product containing less than 1% by mass of an acid ammonium compound or other by-product having an ammonium group (for example, an ammonium acetate compound).

  The method of the present invention can also be used for the production of lithium tetrafluoroborate compounds. That is, producing a lithium tetrafluoroborate compound by reacting at least one lithium salt selected from lithium carboxylate, lithium carbonate and lithium hydrogencarbonate with an ammonium tetrafluoroborate compound. (The following formula).

Next, the present invention will be specifically described with reference to examples, but the scope of the present invention is not limited thereto.
The analysis (qualitative and quantitative) of lithium hexafluorophosphate was based on a sample of lithium hexafluorophosphate (Tokyo Kasei Co., Ltd.), and nuclear magnetic resonance spectra of phosphorus and lithium ( ³¹ P-NMR and ⁷ Li-NMR) and inductively coupled plasma optical emission spectrometry (ICP).
Analysis of ammonium compounds (a raw material ammonium hexafluorophosphate compound and other by-products having an ammonium group (for example, an ammonium acetate compound)) is conducted by proton nuclear magnetic resonance spectrum ( ¹ H-NMR). It was.

Example 1 (Synthesis of lithium hexafluorophosphate)
Under an argon gas atmosphere, in a glass flask having an internal volume of 50 ml equipped with a stirrer, 1.01 g (15.2 mmol) of 99 wt% lithium acetate and 2.50 g of 99 wt% ammonium hexafluorophosphate (2.50 g) 15.2 mmol), 1.44 ml (15.2 mmol) of acetic anhydride and 4 ml of t-butyl methyl ether were added and reacted at room temperature for 2 hours with stirring.
After completion of the reaction, the reaction solution was filtered, and the obtained filtrate was concentrated under reduced pressure to obtain 2.12 g of a white solid. When the obtained solid was analyzed, it contained 1.50 g of lithium hexafluorophosphate (yield: 65%).
Further, the presence of the ammonium compound was not confirmed, and it was found that the obtained lithium hexafluorophosphate had an ammonium compound content of less than 1% by mass.
The physical properties of the obtained lithium hexafluorophosphate were as follows.

³¹ P-NMR (CD ₃ CN, δ (ppm)); -145.0 (7-fold line)
⁷ Li-NMR (CD ₃ CN, δ (ppm)); −1.618 (s)

  According to the present invention, for example, a method for producing lithium hexafluorophosphate useful as a catalyst for organic synthesis reaction or a dopant for semiconductor materials can be provided.

Claims (2)

  A process for producing lithium hexafluorophosphate, comprising reacting at least one lithium salt selected from lithium carboxylate, lithium carbonate and lithium hydrogen carbonate with an ammonium hexafluorophosphate compound .   High purity lithium hexafluorophosphate having an ammonium compound content of 1% by mass or less.