DIFFERENT ROUTES IN THE SYNTHESIS OF (IO)2(SO4)1-X(SEO4)X

The reaction between I2 and I2O5 in mixtures of conc. H2SO4 and H2SeO4 results in a regular solid solution phase (10)2(SO4)1-x(SeO4)x, covering the entire range 0.00 less-than-or-equal-to x less-than-or-equal-to 1.00. Improvements have been introduced in the washing-drying procedure for this product. The contours of a reaction mechanism are discussed. (IO)2(SO4)1-x(SeO4)x can also be prepared virtually pure by means of I2O5 and X = S, Se, P, As, Ge and Sn instead of elementary iodine. With X = Bi and Pb the reaction follows an entirely different course, and for the former element a 'double' solid solution phase, (IO)2-y(BiO)y(SO4)1-x(SeO4)x, is obtained as the reaction product. For X = Te and Pb, the reaction products contain Te2O3SO4 and PbSO4, respectively, in addition to (IO)2(SO4)1-x(Seo4)x. For X = Sb, the reaction product is an amorphous phase, not yet identified. No reaction can be initiated between X = Si and I2O5 in conc. H2SO4(+H2SeO4). The findings are discussed on the basis of the standard reduction potentials for HIO3 and the elements concerned.