Preparation of Organotrifluoroborate Salts: Precipitation-Driven Equilibrium under Non-Etching Conditions

Simple, rapid, and scaleable: In contrast to current procedures using corrosive HF/MF or MHF2 reagents (M=e.g. K), a wide range of trifluoroborates can be rapidly, simply, and safely prepared from MF (M=K, Cs), RCO2H, and a boronic acid/ester in regular glassware (see figure; left versus right). The use of L‐(+)‐tartaric acid as an alkali‐metal sponge is key and allows isolation of RBF3M by a simple stir/filter/evaporate sequence.