Process for preparing triaryl organoborates of the formula 1 / n K n + R 3 4 B − − R 1 where one equivalent of organoboronic ester of the formula B-R 1 (OR 2) (OR 3) is initially charged together with 1/n equivalents of salt K n+ nX - and 3 equivalents of metal M in a solvent or a solvent mixture S1, 3 equivalents of a haloaromatic R 4 -Y are added, an auxiliary L and optionally a second organic solvent or solvent mixture S2 is added and the compound 1 / n K n + R 3 4 B − − R 1 is separated off with the organic phase and R 1 is an optionally hydroxyl- and/or alkoxy- and/or acyloxy- and/or halogen-substituted C 1 - to C 22 -alkyl, C 3 - to C 22 -alkenyl, C 3 - to C 22 -alkynyl, C 5 -to C 7 -cycloalkyl or C 7 - to C 13 -aralkyl radical, R 2 and R 3 are independently an optionally branched C 1 -to C 22 -alkyl radical or an optionally alkyl-substituted C 3 - to C 7 -cycloalkyl radical or R 2 and R 3 together form a 2-8-membered carbon bridge which is optionally substituted by alkyl and/or interrupted by oxygen atoms, R 4 is a C 6 - to C 10 -aryl radical optionally substituted by at least one radical selected from halogen, c 1 -to C 4 -alkyl, trifluoromethyl, c 1 -to C 4 -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 (OR 2), MY (OR 3) 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 alkylamine-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, 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, where the solvents or solvent mixtures S1 and S2 are different from the auxiliary L. R 1 is an optionally hydroxyl- and/or alkoxy- and/or acyloxy- and/or halogen-substituted C 1 - to C 22 -alkyl, C 3 - to C 22 -alkenyl, C 3 - to C 22 -alkynyl, C 5 -to C 7 -cycloalkyl or C 7 - to C 13 -aralkyl radical, R 2 and R 3 are independently an optionally branched C 1 -to C 22 -alkyl radical or an optionally alkyl-substituted C 3 - to C 7 -cycloalkyl radical or R 2 and R 3 together form a 2-8-membered carbon bridge which is optionally substituted by alkyl and/or interrupted by oxygen atoms, R 4 is a C 6 - to C 10 -aryl radical optionally substituted by at least one radical selected from halogen, c 1 -to C 4 -alkyl, trifluoromethyl, c 1 -to C 4 -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 (OR 2), MY (OR 3) 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 alkylamine-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, 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,