Tri-tert-butylphosphonium tetrafluoroborate（Cat No.:R034078）is an organophosphonium salt composed of a bulky tri-tert-butylphosphonium cation and a tetrafluoroborate (BF₄⁻) counterion. The steric bulk of the tert-butyl groups around the phosphorus atom imparts high stability and low nucleophilicity, making the compound useful in organocatalysis and phase-transfer catalysis. The tetrafluoroborate anion enhances solubility in organic solvents and contributes to the salt’s thermal and chemical stability. This compound is often employed as a precursor to tri-tert-butylphosphine or used directly in transition-metal catalyzed reactions, particularly where mild, air-stable phosphorus sources are desired.