Reactions of acetyl radicals. Part 1.—Photolysis of acetone in presence of nitric oxide and of nitrogen dioxide

Abstract

The photolysis of acetone in presence of nitric oxide and of nitrogen dioxide was studied in order to obtain information about the kinetics of acetyl radical reactions. The ratio of nitric oxide to nitrogen dioxide, and the temperature, determine whether nitrogen dioxide is produced or consumed during photolysis. The initial yields of nitrogen dioxide are explained in terms of a competition between nitric oxide and nitrogen dioxide for acetyl radicals. In the temperature range 20–60°C, the reaction CH₃CO+NO₂→CH₃+CO₂+NO is 5 times as rapid as the reaction CH₃CO+NO→CH₃CONO. Evidence for the dissociation CH₃CONO→CH₃CO+NO has been found. The ratio of the dissociation rate constant to that for the reaction CH₃CONO+2NO→CH₃CO+N₂+NO₃ has been evaluated.