TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Process: The reaction takes place at 0-250 degrees C, preferably 30-130 degrees C. The process further uses a sparingly soluble substances, preferably metal fluoride and/or metal chelate salt in powdered form and a catalyst. Preferred Components: (I) is lithium difluorooxalatoborate or lithium malonate difluoro borate. The average particle size of the sparingly soluble substance is less than 100, preferably 50 mu m. The metal fluoride and (III) are used in excess, which is 0.1-100, preferably 1-20 wt.%. The catalyst contains a Lewis acid or a substance, which can release a Lewis acid in the reaction mixture. The catalyst is an element from the group 2-15, preferably molecular halides, perfluoroalkyl, perfluoroaryl and/or oxo compound of boron, aluminum or phosphorus, preferably aluminum alcoholates of formula (Al(OR)3), boric acid ester (B(OR)3), phosphorus oxide or phosphorus halide, preferably lithium hexafluorophosphate. The amount of the catalyst is maximum 20, preferably 5 mol.% with respect to used boron trifluoride.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The solvent is ether, ester, nitrile, lactone, alkyl carbonate in pure form or any mixture, preferably carboxylic acid ester preferably dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, propylene carbonate or ethylene carbonate, cyclic ether such as tetrahydropyran or tetrahydrofuran, polyether such as 1,2-dimethoxyethane or diethylene glycol dimethyl ether, further nitrile such as acetonitrile, adiponitrile, malononitrile or glutaronitrile or lactone such as gamma -butyrolactone. Preferred Definitions:    M+ = Li+; and    L = oxalate or malonate.    EXAMPLE - Lithium bis(oxalato)borate (37.5 g) and lithium oxalate (19.8 g) in anhydrous dimethyl carbonate (229 g) were heated at 70 degrees C. Then, boron trifluoride etherate (55 g) were added within one hour and the temperature was adjusted so that the reaction mixture was slightly boiled. After dosing, the mixture was further refluxed to obtain lithium difluorooxalatoborate.