The effect of iodine on the peroxidation of carbonyl compounds.
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 also converted to gem-dihydroperoxides with hydrogen peroxide and iodine as catalyst in acetonitrile and to hydroperoxyacetal in methanol, while the reactivity of aliphatic ones remained the same as in noncatalyzed reactions. tert-Butylhydroperoxide reacted in a similar manner, giving the corresponding perether derivatives. A study was also made of the relative kinetics of dihydroperoxidation from which the Hammet equation gave a reaction constant (rho) of -2.76, indicating the strong positive charge development in the transition state and the important role of rehybridization in the conversion of hydroperoxyhemiketal to gem-dihydroperoxide. In acetonitrile, the iodine catalyst is apparently able to discriminate between the elimination of a hydroxy, methoxy, and hydroperoxy group and addition of water, methanol, and H2O2 to a carbonyl group.
Zmitek
Katja
K
Laboratory of Organic and Bioorganic Chemistry, JoZef Stefan Institute, Jamova 39, Ljubljana, Slovenia.
Zupan
Marko
M
Stavber
Stojan
S
Iskra
Jernej
J
D000447:Aldehydes / Q000737:chemistry; D007455:Iodine / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry; D010545:Peroxides / Q000737:chemistry*
D000447:Aldehydes; D007659:Ketones; D010545:Peroxides; D007455:Iodine