EFFECTS OF ADDED ANIONS ON THE REACTION OF NITROUS-ACID WITH HYDROGEN-PEROXIDE

The reactions of nitrous acid with hydrogen peroxide in acidic aqueous solution in the presence of several added anions have been studied at 0-degrees-C and pH 2-4 to investigate the nucleophilic catalysis of these anions. From the dependence of reaction rates on the anion concentrations, significant catalytic effects were found for Cl-, Br-, SCN-, in order of effect SCN almost-equal-to Br- > Cl-, while no observable effect was found for ClO4- and NO3-. These results support O-nitrosation reaction is the rate-determining step and NOX formed in the presence of an anion (X-) also acts as a nitrosating agent and accelerates the overall reaction rate. The order of reactivity was found to be NOCl > NOBr > NO-SCN, which is consistent with the results of N-nitrosation and S-nitrosation reactions.