과요오드 산 (수화물)

Periodic acid exists as colorless crystals, soluble in water and ethanol but slightly soluble in ether. Upon dehydration, it forms metaperiodic acid (HIO₄). Further dehydration leads to decomposition, ultimately yielding iodine pentoxide (I₂O₅).

생산 방법A 100 g quantity of Ba₃H₄(IO₆)₂ is moistened with 75 mL of H₂O and treated with 200 mL of colorless nitric acid (HNO₃). The mixture is agitated, heated to 60–70 °C for 1 h, and then cooled to 30–40 °C. The precipitated Ba(NO₃)₂ is filtered off using a glass frit filter. The residue is washed free of periodate by stirring with concentrated HNO₃. The combined filtrate is evaporated at 60–70 °C under aspirator vacuum (if additional Ba(NO₃)₂ precipitates, it is removed by filtration, and evaporation continues) until H₅IO₆ begins to crystallize. After cooling, colorless, glistening crystals of periodic acid (H₅IO₆) form. Due to the tendency of the solution to become supersaturated, prolonged waiting may be required. The crystals are collected by filtration and dried under vacuum at 50 °C. A second crop of crystals may be obtained by further evaporating the mother liquor.