CATIONS AND OXYCATIONS OF IODINE .6. SOLUTIONS OF SOME IODINE COMPOUNDS IN DISULFURIC ACID

The blue solutions of iodine in oleum have been reinvestigated using both H2S2O7 (45% oleum) and 65% oleum as a solvent by cryoscopy, conductivity, and absorption spectra measurements. It is concluded that iodine is oxidized to the I2+ cation although the oxidation is apparently not complete in H2S2O7 at 25°. KI and ICl also produce the I2+ cation in oleum, the latter by disproportionation to I2+ and I(SO4H)2+. ICl3 ionizes to give the ICl2+ ion. Sulfur dioxide which is a product of the oxidation of iodine is shown to be a nonelectrolyte. There is no evidence that the +1 oxidation state of iodine is stable in oleum either as the cation I+ or in any other form. © 1969, American Chemical Society. All rights reserved.