Peroxidation of ketones and aldehydes with iodine as a catalyst was studied. Ketones reacted with 30% aq hydrogen peroxide in the presence of 10 mol% of iodine to yield gem- dihydroperoxides in acetonitrile and hydroperoxyketals in methanol. The yield of hydroperoxidation of various cyclic ketones was 60-98%, including androstane-3, 17-dione, while acyclic ketones were converted with a similar efficiency. Aromatic aldehydes were ...