2KReO4 + 10HCl + 2KCl + 3H3PO2 → 2K2[ReCl6] + 3H3PO3 + 5H2O
Potassium perrhenate react with hydrogen chloride, potassium chloride and hypophosphorous acid to produce hexachloridorhenate(IV) potassium, phosphorous acid and water. Hydrogen chloride and Hypophosphorous acid - concentrated solutions.