A study of the solution phase photochemistry of the nitrous acid/nitrite ion system in both water and non-aqueous solvents has been undertaken. Photolysis at 366nm of the aqueous system is known to form hydroxyl radical and nitric oxide. The relative contributions of the molecular and ionic forms to the photochemical production of radicals is unknown. Scavenging reactions of the hydroxyl radicals in aqueous and nonaqueous solution are used to determine the relative production of OH. formed by photolysis of HONO and N02-. Molecular nitrous acid is isolated from its conjugate base by extraction into benzene from water. The thermal decomposition of HONO in the extraction mixture was measured and it was found to be second order with respect to nitrous acid. The product of the photolysis of this benzene solution, PNP, indicates hydroxyl radical formation. Nitrite ion dissolves in aprotic solvents, such as DMF and DMSO, without the formation of nitrous acid. Photolysis of these solutions appears to result in the formation of phenol only. The quantum yield for the formation of phenol was determined to be 1.8 ± 0.3 x 10-2 mol/eins.



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