Francis T. Bonner

The aqueous solution chemistry of nitrogen in low positive oxidation states

Abstract Recent developments in the aqueous solution chemistry of nitrogen are described, with particular attention to the low positive oxidation states +1 and +2. The compounds discussed include hyponitrous acid and hyponitrites, nitrosyl hydride (HNO, “nitroxyl”), trioxodinitrate, nitric oxide, and nitroamine. The numerous redox pathways in which these and other nitrogen compounds are participants illustrate the versatility of that element, and bear important relation to current problems in nitrogen cycle research that focus upon the identity and reactivity of nitrogen species in intermediate oxidation states.

Reaction of nitric oxide with hyponitrous acid: a hydrogen atom abstraction reaction

La reaction a lieu avec et sans inhibiteur de chaine (C 2 H 5 OH). Mesure des rendements en N 2 , N 2 O. Mecanismes

Nitrogen isotope exchange between nitric and nitrous acids

The rate of nitrogen isotrope exchange between NO−3 and NO−2 in aqueous solution has been measured, at low acidity, as a function of pH, [NO−3], [NO2−], and temperature. Exchange does not occur in the absence of NO, and during slow exchange processes NO and NO2− remain closely similar in isotopic content. The exchange rate law is shown to be R=k[H+][HNO2][NO−3], and the measured activation parameters are EA=74.4±2.6 kJ, ΔH‡=72.0±2.6 kJ, ΔS‡=−97.4±8.5 JK−1. It is concluded that there is no direct interaction pathway for nitrate–nitrite exchange, and that this process and NO–HNO3 exchange both occur via the reversible HNO2 disproportionation reaction, involving N2O4 as intermediate.

Stoicheiometric and nitrogen-15 labelling studies on the hyponitrous acid–nitrous acid reaction

The stoicheiometry of the hyponitrous acid–nitrous acid reaction has been determined over a wide acidity range, up to 8.5 mol dm–3 HClO4. For approximately 1 : 1 reaction conditions, the major reaction pathway gives N2 and HNO3 as products, together with the production of N2O (by self decomposition of hyponitrous acid) and NO (by self decomposition of nitrous acid). In addition, 15NO produced by self decomposition of H15NO2 reacts with H214N2O2 to give some 14NO and N2O of mixed isotopic composition. Reactions under other conditions gave products that may be accounted for by varying contributions from these reactions.