Tetrabromophenol blue alkali metal salt and preparation method and application thereof

The invention provides tetrabromophenol blue alkali metal salt as well as a preparation method and application thereof, and belongs to the technical field of tetrabromophenol blue salification. The tetrabromophenol blue alkali metal salt is tetrabromophenol blue lithium salt, tetrabromophenol blue sodium salt and tetrabromophenol blue potassium salt; the preparation method of the tetrabromophenol blue alkali metal salt comprises the following steps: carrying out salt forming reaction and crystallization on tetrabromophenol blue and alkali metal salt in an aprotic solvent to prepare a crude product, and recrystallizing in the aprotic solvent to prepare a pure tetrabromophenol blue alkali metal salt. According to the preparation method of the tetrabromophenol blue alkali metal salt, the problem that existing tetrabromophenol blue is poor in water solubility is solved, and the preparation process is simple in method, mild in condition, high in product purity, high in yield, low in cost, capable of being produced