Nitrosation of Organic Hydroperoxides by Nitrogen Dioxide/Dinitrogen Tetraoxide

Article abstract of DOI:10.1021/ja00287a039

Cumyl and tert-butyl hydroperoxides react rapidly with NO2/N2O4 in organic solvents in the presence of a base to form the organic nitrate (RONO2) as the major product, together with smaller amounts of the corresponding nitrite (RONO), alcohol, and carbonyl compound (acetophenone or acetone from cumyl and tert-butyl hydroperoxide, respectively).The products from tert-butyl hydroperoxide are similar whether a base is present or not but those from cumyl hydroperoxide are more complex.We have formulated the initial reaction as a nitrosation of the hydroperoxide by N2O4 to give the pernitrite ester.This latter species is unstable and either rearrenges to give the nitrate or dissociates to form alkoxyl radicals and nitrogen dioxide that ultimately give the other observed products.The kinetics of the reaction were studied by stopped flow and are complex, but we conclude the kinetics are consistent with the nitrosation mechenism.The rate constants at 30 deg C are 2.4*10⁴ and 8.1*10³ M^-1 s^-1 for tert-butyl and cumyl hydroperoxides, respectively.We suggest that this facile reaction of NO2/N2O4 with hydroperoxides may have important consequences respect to the pulmonary toxicity of NO2 in smoggy air.