The photochemical decomposition of methyl iodide in presence of nitric oxide - II. Reactions of nitrosomethane

A product of the photolysis, in presence of a small quantity of nitric oxide, of methyl iodide reacts with excess nitric oxide to form a substance(s), Y, which absorbs light throughout the wavelength region 2300 to 5300 Å. The initial products of the photolysis, in presence of small quantities of nitric oxide, of both acetone and acetaldehyde react similarly. The species undergoing the reaction is believed to be monomeric nitrosomethane, formed by the association of methyl radicals with nitric oxide. The order of the reaction to form Y, as determined by the initial rate method, is one with respect to nitrosomethane and two with respect to nitric oxide. The extent of the reaction, which can be used as a measure of nitrosomethane concentration, depends on the concentration of nitric oxide. In absence of excess nitric oxide the monomer disappears slowly from the gas phase in a second-order reaction, which is thought to be the dimerization to nitrosomethane dimer.