Visible Light Induced Reactions of NO2 with Conjugated Dienes in a Low-Temperature Ar Matrix

Article abstract of DOI:10.1021/j100129a020

Visible light induced oxygen atom transfer from NO2 to conjugated dienes has been investigated in a low-temperature Ar matrix, where the dienes are 1,3-butadiene (BD), 2-methyl-1,3-butadiene (isoprene), and 2,3-dimethyl-1,3-butadiene (DMB).In each diene/NO2/Ar system, the corresponding nitrite radical, oxirane, aldehyde, and NO were obtained as the photochemical reaction products.The reactions are initiated by the formation of undetecteable short-lived oxirane biradical and NO due to visible light induced O atom transfer from NO2 to the conjugated dienes. (1) The recombination of oxirane biradicals and neighboring NO gives the nitrite radicals as the photochemical intermediate. (2) The ring closure of the biradicals leads to the formation of oxiranes. (3) The intramolecular H atom transfer of biradicals leads to the formation of aldehydes.The visible photolysis of the nitrite radicals gives rise to oxirane, aldehyde, and NO.The reaction rates are derived by measuring the absorbance changes of the products upon the 582-nm irradiation.The methyl substituent effect on the reactivity is discussed.