DD290889A5 - METHOD FOR THE PRODUCTION OF TETRAACETONITRILLITHIUM SALTS OF HEXAFLUOROELEMENTSAEURES WITH THE ELEMENTS ARSEN OR PHOSPHORUS - Google Patents

Abstract

The invention relates to a process for the preparation of Tetraacetonitrillithiumsalzen of Hexafluoroelementsaeuren with the elements arsenic or phosphorus. The Tetraacetonitrillithiumsalze of Hexafluoroelementsaeuren & Li (CH3CN) 4! EF6 with EAs or P are starting materials for the representation of highly pure lithium salts of Hexafluoroelementsaeuren LiEF6 with the importance explained for E, which are used as conductive salts in a non-aqueous electrolyte for rechargeable lithium batteries. The aim of the invention is to find a simple process for preparing the title compounds in high purity and yield. Very pure Tetraacetonitrillithiumsalze the Hexafluoroelementsaeuren & Li (CH3CN) 4! EF6 with EAs, P are by reacting a lithium salt LiX with X halide, BF 4 or C10 4 with a salt of HexafluoroelementsEure YEF6, where E has the meaning explained above and Y for an alkali metal ion , an ammonium ion or an alkylammonium ion, in acetonitrile and subsequent selective extraction. {Tetraacetonitrillithium hexafluoroarsenate; Tetraacetonitrillithium hexafluorophosphate; lithium hexafluoroarsenate; lithium; conductive salt; Lithium Battery; acetonitrile; selective extraction}

Description

Field of application of the invention

The invention relates to a process for the preparation of Tetraacetonitrillithiumsalzen of Hexafluoroelomontsäuren the general formula [Li (CH ₃ CN) ₄ IEF ₈ with E = As odor P, which are as intermediates in the production of conductive salts in non-aqueous electrolyte for wioderaufladbaro lithium batteries of importance ,

Characteristic of the known state of the art

Tetraacetonitrillithium salts of Hoxafluoroelcmentsäuren [Li (CH ₃ CN) ₄ ] EFu with E = As or P are required for the crude representation of LiEFg and by dissolving technical lithium salts of Hoxafliiorolcmentsäuren LiEF ₈ with E = As or P in acetonitrile shown (US 3654330). The (Li (CH ₃ CN) ₄ IPF ₈ can also be prepared by reacting LiF with PF * in acetonitrile (US 3654330)

 These methods have the following disadvantages:

- The lithium salts of Hexafluorelomontsäuren LiEF ₈ are in contrast to the other alkali metal salts of Hexafluoroelementsäursn representable substances only with great effort and not available by the known methods in the purity required for their use as conductive salt.

- PF ₆ is a highly reactive and therefore difficult to handle substance. It is also representable only with great effort.

Object of the invention

The object of the invention is to provide high-purity tetraacetonitrile-lithium salts of hexafluoro-elemental acids with the elements arsenic or phosphorus for use as starting materials for the preparation of lithium salts of hexafluoro-elemental acids required as conductive salts in nonaqueous electrolytes for rechargeable lithium batteries.

Explanation of the essence of the invention

The invention has for its object to develop a process for the preparation of Tetraacetonitrillithiumsalzen of Hexafluoroelementsäuren with the elements arsenic or phosphorus, starting from easily accessible and easy to handle starting materials.

According to the invention, this object is achieved in that a lithium salt LiX with X = halide, BF ₄ "or CIO ₄ " with a salt of a Hexafluoroelementsäure YEF ₆ , wherein E for As odor P and Y for an alkali ion or R _n NH ₄ .. _n ⁺ with R = alkyl and η = 0-4, reacted in a molar ratio of 1: 1 to 1: 3 at a temperature of 0 ° C to 80 ° C in acetonitrile, wd. The reaction product is then by extraction with a organic solvents isol.jrt. The reaction takes place according to the following reaction equation.

CH, CN LiX + YEF ₆ - ^ [Li (CH ₃ CN) ₄ ] EF ₆ + YX

The lithium salt LiX used is preferably LiBr. As the salt of hexafluoroelement acid YEF ₁ , KAsFg or KPF ₉ are preferably used. The lithium salt LiX is preferably reacted with the salt of a hexafluoroelement acid in a molar ratio of 1: 2. The reaction is preferably carried out at 55 ^° C. After filtration from the co-precipitated accompanying product YX and removal of the excess non-complexed acetonitrile, the reaction product ILi (CH ₃ CN) ₄ ) EF ₆ is quenched from the reaction mixture by addition of a halogenated hydrocarbon, preferably methylon chloride, or by adding a mixture of different halogenated hydrocarbons and freed by filtration of insoluble impurities and excess starting material. After removal of the organic solvent, the crude product (Li (CH ₁ CN) ₄ IEF ₆ remains crystalline

 The ancestor according to the invention has the following decisive advantages.

1. It allows the recovery of high purity Tetraacotonitrillithiumsalze of Hexafluoroelementsäuren (Li (CH ₃ CN) ₄ ] EF ₆ on the basis of easily accessible lithium salt LiX and easily representable and easy to handle Hexafluoroarsenate or phosphates.

2. The favorable Löslichkeitseigonschafton dor compounds in acetonitrile and the surprisingly solive extraction of the reaction product with a halogenated hydrocarbon unnecessary additional, mo so expensive and lossy purification steps.

3. The required degree of purity of the starting materials is low.

4. The synthesis can be carried out in glass apparatus.

5. The carefully dried solvents and the excess salt of a Hoxafluoroelomentsäure YEF ₈ can be used in a cyclic process.

Exemplary embodiments Preparation of [LI (CHiCN) ₄ ] AsF, In a dry glass flask, 0.5 mol LiBr in acetonitrile are dissolved under nitrogen atmosphere, and 1 mol KAsF ₆ , also

as a solution in acetonitrile, with vigorous stirring for one hour at 55 ⁰ C added dropwise. The reaction mixture becomes

Removal of the precipitated KBr filtered and excess, not complexed acetonitrile removed in vacuo. The

Crystalline precipitated mixture of KAsF ₆ and (Li (CH ₃ CN) ₄ IAsF ₆ is triturated in methylene chloride and the solution is separated by filtration from anhydrous KAsF _6. After evaporation of the methylonchloride in vacuo, the crystalline (Li (CH ₃ CN) ₄ ) remains. AsF ₆ with a yield of over 94%, based on LiBr used, in very good purity.

The product obtained from this product according to U.S. Patent No. 3654330 by desorption of the acetonitrile as a fine crystalline powder LiAsF ₆ has a bromide content of less than 10ppm and no detectable potassium contamination. Preparation of [Li (CH) CN) ₄ ] PF. The illustration is analogous to the representation of [Li (CH ₃ CN) ₄ ] AsF ₆ with KPF ₆ instead of ICAsF ₆ . The yield is 90% and

the purity of the product is 99.7%.

Claims (6)

A process for the preparation of tetraacetonitrillithium salts of hexafluoro-elemental acids with the elements arsenic or phosphorus of the general formula [Li (CH ₃ CN) ₄ IEF ₆ , in which E is As or P, characterized in that lithium salt LiX with X = halide, BF ₄ "or CIO ₄ " with a salt of a Hexafluoroelementsäure YEF ₆ , wherein E has the meaning explained above and Y is an alkali ion or R _n NH ₄ _ _n ^f with R = alkyl and η = 0-4, in one Molar ratio 1: 1 to 1: 3 reacted at a temperature of 0 ⁰ C to 80 ⁰ C in acetonitrile and the reaction product is isolated by extraction with an organic solvent. 2. The method according to claim 1, characterized in that LiBr is preferably used as the lithium salt LiX. 3. The method according to claim 1, characterized in that KAsF ₆ or KPF ₆ is preferably used as the salt of Hexafluoroelementsäure YEF ₆ . 4. The method according to claim 1 to 3, characterized in that the lithium salt LiX is preferably reacted with the salt of the hexafluoroacetic YEF ₆ in a molar ratio of 1: 2. 5. The method according to claim 1, characterized in that for extraction as an organic solvent, a halogenated hydrocarbon, preferably methylene chloride, or a mixture of different halogenated hydrocarbons is used. 6. The method according to claim 1, characterized in that the reaction is preferably carried out at a temperature of 55 ° C.