Nitric oxide aqueous chemistry

Nitric oxide is the simplest thermally stable odd-electron molecule known and, accordingly, its electronic structure and reaction chemistry have been very extensively studied. The compound is an intermediate in the production of nitric acid and is prepared industrially by the catalytic oxidation of ammonia (p. 466). On the laboratory scale it can be synthesized from aqueous solution by the mild reduction of acidified nitrites with iodide or ferrocyanide or by the disproportionation of nitrous acid in the presence of dilute sulfuric acid ... 

Bonner, F. T., and Pearsall, K. A. (1982). Aqueous nitrosyliron(ll) chemistry. 1. Reduction of nitrite and nitric oxide by iron(ll) and (trioxodinitrato)iron(ll) in acetate buffer. Intermediacy of nitrosyl hydride. Inorg. Chem. 21, 1973-1978. 

Cerium (IV) in solution is obtained by treatment of Ce111 solutions with very powerful oxidizing agents, for example, peroxodisulfate or bismuthate in nitric acid. The aqueous chemistry of CeIV is similar to that of Zr, Hf, and, particularly, tetravalent actinides. Thus Ce gives a phosphate insoluble in 4 M HN03 and an iodate insoluble in 6 M HN03, as well as an insoluble oxalate. The phosphate and iodate precipitations can be used to separate Ce from the trivalent lanthanides. Ce is also much more readily extracted into organic solvents by tributyl phosphate and similar extractants than are the Lnm lanthanide ions. 

Davies KM, Wink DA, Saavedra JE, Keefer LK. 2001. Chemistry of the diazeniumdio-lates. 2. Kinetics and mechanism of dissociation to nitric oxide in aqueous solution. J. Am. Chem. Soc. 123 5473-81... 

The second step is the reduction of nitric oxide in an aqueous sulfuric acid solution to produce hydroxylamine sulfate. This proceeds according to the chemistry illustrated in Eq. (27) ... 

Liittke, I, Scheer, V, Levsen, K., Wunsch, G, Cape, J. N., Hargreaves, K. X, Storeton-West, R. L., Acker, K., Wieprecht, W. and B. Jones (1997) Occurrence and formation of nitrated phenols in and out of clouds. Atmospheric Environment 31, 2637-2648 Lymar, S. V, V. Shafirovich and G. A. Poskrebyshev (2005) One-electron reduction of aqueous nitric oxide a mechanistic revision. Inorganic Chemistry 44, 5212-5221 Maahs, H. G. (1983) Measurement of the oxidation rate of sulphur(IV) by ozone in aqueous solution and their relevance to SO2 conversion in nonurban tropospheric clouds. Atmospheric Environment 17, 341-345... 

The aqueous chemistry of NO has been extensively studied. Nitric oxide has a modest solubility of 1.9 mM in water under 1 atm of NO. Descriptions of its reactivity have tended to be highly variable. Recent work indicates that NO is not highly reactive, despite having an unpaired electron, but reacts with O2 to form reactive species. Traces of Oj are the probable source of different conclusions about the reactivity of NO. It should be noted that there have been some recent studies of the general properties of species involved in these sterns, such as the pulse radiolysis of NO, the pK, values of HNOj and 1 0, the reduction potential of NO. and the AGf of ONOjH. ... 

Silver has little tendency to formally lose more than one electron its chemistry is therefore almost entirely restricted to the + 1 oxidation state. Silver itself is resistant to chemical attack, though aqueous cyanide ion slowly attacks it, as does sulphur or a sulphide (to give black Ag S). hence the tarnishing of silver by the atmosphere or other sulphur-containing materials. It dissolves in concentrated nitric acid to give a solution of silver(I) nitrate. AgNOj. 

An overview is presented of plutonium process chemistry at Rocky Flats and of research in progress to improve plutonium processing operations or to develop new processes. Both pyrochemical and aqueous methods are used to process plutonium metal scrap, oxide, and other residues. The pyrochemical processes currently in production include electrorefining, fluorination, hydriding, molten salt extraction, calcination, and reduction operations. Aqueous processing and waste treatment methods involve nitric acid dissolution, ion exchange, solvent extraction, and precipitation techniques. 

It is known from studies carried out over many decades that oxides of nitrogen at high concentrations dissolve in aqueous solution and react to form species such as nitrate and nitrite. With the focus on acid deposition and the chemistry leading to the formation of nitric and sulfuric acids during the 1970s and 1980s, a great deal of research was carried out on these reactions at much lower concentrations relevant to atmospheric conditions (for reviews, see Schwartz and White, 1981, 1983 and Schwartz, 1984). 

Protons present in aqueous acid also act as reasonably efficient electron acceptors. If the reduced hydrogen atoms are formed on metallized suspensions, catalytic hydrogenation can result. For example, in contrast to the oxidative chemistry reported earlier for cyclohexene-4,5-bis-dicarboxylic acid (Eq. 28), if the reaction is conducted in the absence of oxygen in aqueous nitric acid, catalytic hydrogenation of the double bond becomes a major pathway, Eq. (34). ... 

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