Synthesis and characterization of pentafluoroethyl peroxynitrate, C2F5OONO2. Photooxidation of C2F5C(O)Cl in the presence of NO2

ADRIANA G. BOSSOLASCO; FABIO E. MALANCA *; GUSTAVO A. ARGÜELLO

Mendoza

Congreso; 21st IAPS Winter Conference; 2011

IAPS

Peroxynitrates (ROONO2) are important species in the atmosphere because they act as reservoirs of NO2 and ROO. radicals. Their atmospheric thermal lifetimes (from hours to several days) are sufficiently long to be transported from their sources to remote places or to the stratosphere. Industrial compounds such as chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (HFCs), and hydrofluoroethers (HFEs) lead to the formation of fluorinated peroxynitrates, for example, trifluoromethyl (CF3OONO2), trifluoroacetyl (CF3C(O)OONO2), and trifluoromethoxycarbonyl (CF3OC(O)OONO2) peroxynitrates. In this work we present the photochemical synthesis and characterization of pentafluoroethyl peroxynitrate, C2F5OONO2. The synthesis was carried out by photolysing C2F5C(O)Cl at 254nm (that provides the C2F5 fragment)5 in presence of NO2 and O2. To establish the correct experimental conditions for the synthesis, the mechanism of photooxidation of C2F5C(O)Cl in the presence of NO2 and O2 was previously studied. Photolysis was run in a standard infrared glass cell, located in the optical path of a FTIR equipment to follow the temporal variation of reactant and products The photolysis leads to the formation of C2F5OONO2 (54%), CF2O (63%), CF3ONO2 (12%) and CO as the main carbonated products, at short photolysis time. As time evolves, the CO concentrations increase in the system and NO2 decrease, leading to the formation of CF2O, CO2 and CF3OC(O)OONO2. It can be seen a slow disappearance of C2F5OONO2, which act as a reservoir of the NO2 needed for the production of CF3OC(O)OONO2. A complete reaction mechanism explaining the formation of the products is presented.