Method of producing tetrakis (pentafluorophenyl) borate derivatives using pentafluorophenyl alkali metal salt prepared from pentafluorobenzene

A method of producing tetrakis(pentafluorophenyl)borate of the molecular formula

• (C.sub.6 F.sub.5).sub.4 BM (VII),
• wherein M denotes an alkali metal ion, comprising reacting 1 equivalent of pentafluorobenzene of the following formula
• C.sub.6 HF.sub.5 (I),
• with 0.5 to 1.5 equivalents of organometallic compound represented by the formula
• RM (II),
• wherein M denotes an alkali metal ion, R denotes a hydrocarbon group with carbon atoms of 1 to 10 and the said hydrocarbon group may contain functional groups having no influence on the reaction, at a temperature in the range of -120.degree. to 80.degree. C., in an ether type solvent, a hydrocarbon type solvent or a mixture of the ether type solvent with the hydrocarbon type solvent, to generate pentafluorophenyl alkali metal salt represented by the formula
• C.sub.6 F.sub.5 M (III),
• wherein M denotes an alkali metal ion, and, then, reacting 1 equivalent of a boron compound represented by the formula
• BX.sub.3 (IV),
• wherein X denotes a halogen atom, a substituent of the formula
• OR (V),
• wherein R denotes a hydrocarbon group with carbon atoms of 1 to 10 and the said hydrocarbon may contain functional groups having no influence on the reaction, or a substituent represented by the formula
• NR'R" (VI),
• wherein R' and R" denote identically or differently hydrogen atoms or hydrocarbon groups with carbon atoms of 1 to 20, wherein said hydrocarbon group may contain functional groups having no influence on the reaction and R' and R" may link one another to form a ring, and may form 1:1 complex with the ether type solvent, with not less than 3.7 equivalents of pentafluorophenyl metal compound of the formula (III).