5019. Iodine Pentoxide

Nomenclature

CAS number: 12029-98-0
Iodic anhydride.
I2O5; mol wt 333.81.
I 76.03%, O 23.96%.

Description and references

Prepd by thermal dehydration of iodic acid at 195°: Lamb et al., J. Am. Chem. Soc. 42, 1644 (1920). Crystal structure: Selte, Kjekshus, Acta Chem. Scand. 24, 1912 (1970).

Properties

Needle shaped, hygroscopic crystals (an impure product may have a pink cast). d25 5.08. Decompn into I2 and O2 begins at 275° and proceeds rapidly at 350°. Very sol in water (187.4 g/100 ml at 13°) forming HIO3. Insol in abs alc, ether, chloroform, carbon disulfide. Dissolves in nitric acid from which it crystallizes as I2O5 if the HNO3 concn is >50%. Strong oxidizing agent, may detonate when triturated with oxidizable matter. Keep well closed and protected from light.

Use

Oxidizes carbon monoxide to carbon dioxide with the formn of iodine (Ditte's reaction, which proceeds rapidly at 65° or above, but slowly at room temp). This reaction is used in gas analysis and for removing carbon monoxide from the air (in respirators preferably in presence of some H2SO4).