Method for producing triarylorganoborates

Process for preparing triaryl organoborates of the formula 1/n Kn+R34B−—R1 (IV), where one equivalent of organoboronic ester of the formula B—R1(OR2)(OR3) (I) is initially charged together with 1/n equivalents of salt Kn+ nX− (II) and 3 equivalents of metal M in a solvent or a solvent mixture S1, 3 equivalents of a haloaromatic R4—Y (III) are added, an auxiliary L and optionally a second organic solvent or solvent mixture S2 is added and the compound 1/n Kn+ R34BB−—R1 (IV) is separated off with the organic phase and

• R1 is an optionally hydroxyl- and/or alkoxy- and/or acyloxy- and/or halogen-substituted C1- to C22-alkyl, C3- to C22-alkenyl, C3- to C22-alkynyl, C5- to C7-cycloalkyl or C7- to C13-aralkyl radical,
• R2 and R3 are independently an optionally branched C1- to C22-alkyl radical or an optionally alkyl-substituted C3- to C7-cycloalkyl radical or R2 and R3 together form a 2-8-membered carbon bridge which is optionally substituted by alkyl and/or interrupted by oxygen atoms, or R2 and R3 together form a 4-7-membered, optionally substituted, carbocycle,
• R4 is a C6- to C10-aryl radical optionally substituted by at least one radical selected from halogen, C1- to C4-alkyl, trifluoromethyl, C1- to C4-alkoxy, trifluoromethoxy, phenyl and phenoxy,
• K is an organocation of valency n and having any substitution, based on nitrogen, phosphorus, oxygen, sulfur and/or iodine, and
• L is an auxiliary that forms a complex of sparing solubility in S1 and/or S2 with M salts MY(OR2), MY(OR3) and MXY, where L is a Lewis-basic compound, selected from the group consisting of open chain or cyclic or polycyclic ethers or polyethers or (poly)ether polyols, amine-functionalized and/or alkanolamine-functionalized alcohols or polyols or (poly)ether polyols, weakly basic organic compounds, weakly acidic macroporous cation exchangers and weakly alkaline macroporous cation exchangers,
• M is any metal selected from the alkali metals, or from magnesium, calcium and aluminium,
• X is a halide or alkoxide or alkyl sulfide,
• Y is iodine or bromine or chlorine,
• n is 1, 2 or 3,
• S1 is an aprotic organic solvent or a mixture of aprotic solvents and
• S2 is an aprotic organic solvent or a mixture of aprotic solvents.