Nitric oxide from hydroxylamines

Hooper, A. B., and Terry, K. R. (1979). Hydroxylamine oxidoreductase of Nitrosomonas production of nitric-oxide from hydroxylamine. Biochimica et Biophyska Acta 571, 12-20. 

Hooper AB, Terry KR (1979) Hydroxylamine oxidoreductase of Nitrosomonas. Production of nitric oxide from hydroxylamine. Biochim Biophys Acta 571 12-20 Hooper AB, Terry KR, Maxwell PC (1977) Hydroxylamine oxidoreductase of Nitrosomonas. Oxidation of diethyldithiocarbamate concomitant with stimulation of nitrite synthesis. Biochim Biophys Acta 462 141-152... 

C-Nitroso compounds, oximes, N-hydroxyguanidines and N-hydroxyureas each contain an N-O bond and release nitric oxide (NO) or one of its redox forms under some conditions. The nitrogen atom of a C-nitroso compound formally exists in the +1 oxidation state, the same oxidation state as nitroxyl (HNO), the one-electron reduced form of N O. The nitrogen atoms of oximes, N-hydroxyguanidines, and N-hydroxyureas each formally exist in the -1 oxidation state, the same oxidation state as hydroxylamine. Consequently, the direct formation of NO (formal oxidation state = +2) from any of these species requires oxidation, one electron for a C-nitroso compound and three electrons for an oxime, N-hydroxyguanidine or N-hydroxyurea. This chapter summarizes the syntheses and properties, NO-releasing mechanisms and the known structure-activity relationships of these compounds. 

There is a remarkable fact about the reaction between nitric oxide and stannous chloride. At a temp, of fully 100°, there is no action between nitric oxide and acid stannous chloride soln. The stannous chloride remains unchanged for hours together, and neither nitrogen nor hydroxylamine is formed. The only thing we have noticed is always a trace of ammonia in experiments at 100°, and this, we are inclined to believe, is due to some other cause than this reaction alone. At 90°, the action is still exceedingly small, but as the temp, descends from about 80°, it becomes rapidly greater with the descent. 

A soln. of sodium nitrate in oono. sulphuric acid in the absence of air acquires under the action of mercury, copper, or silver an intense blue colour, which gradually fades the colourless soln. contains nitrous oxide. Nitrosulphonic acid forms with a soln. of sulphur dioxide in sulphurio acid a blue soln. from which nitric oxide is quantitatively evolved, 2N02.S03H+S0j+2Hj0 = 2N0+3HsS04. Nitric oxide is absorbed by copper sulphate dissolved in cone, sulphuric acid in the mol, ratio 1 1 at atm. temp, and press. the conception that the dark blue soln. contains the copper salt of nitrosisulphonic acid is strengthened by the observation that hydroxylaminesulphonic acid is oxidized by mono-persulphuric acid in presence of sulphuric acid and a trace of copper to a dark blue compound, whereas hydroxylamine is not similarly affected. 

Raman, S., Ashcraft, R.W., Vial, M., Klasky, M.L. 2005. Oxidation of hydroxylamine by nitrous and nitric acids. Model development from first principle SCRF calculations. J. Phys. Chem. A, Mol. Spectrosc. Kinet. Environ. Gen. Theory 109 (38) 8526-8536. 

The overall reaction is energy yielding, and allows sufficient ATP production to support reverse electron transport for CO2 fixation. However, the first step, oxidation of NH3 to hydroxylamine, requires the input of reducing power. The second step, hydroxylamine oxidation, yields four electrons. These join the electron transport chain at the level of ubiquinone, from which two are shunted back to AMO for activation of NH3. The N oxidation and electron transport pathways in Nitrosomonas are linked in the cytoplasmic membrane and periplasmic space detailed information from the N. europaea genome (Chain et al., 2003) is consistent with the previous biochemical characterizations of the system (Whittaker et al., 2000). Depending on conditions (and enhanced at low oxygen concentrations), nitric oxide (NO), nitrous oxide (N2O) and even dinitrogen gas (N2) have been reported as secondary products... 

Hydroxylamine acts as a reducing agent when absorbed systemically, producing methemoglobin and the formulation of Heinz bodies in the blood. It can induce hemolytic anemia. It inhibits platelet aggregation and is a nitric oxide vasodilator. Oxy-Imines such as hydroxylamine and methoxylamine disturb DNA replication and act as potent mutagens, causing nucleotide transition from one purine to another or one pyrimidine to another. 

The ultimate loss of the HAS activity occurs by destruction of the heterocycle initiated thermally, photochemically, chemically or by high-energy radiation. An intramolecular H-abstraction from the p-carbon atom in thermolysis of 2,2,6,6-tetramethyl-4-oxo-piperidinyl-l-oxyl 133 via a general reaction (Eq. 8) was proposed as a pathway of thermal selfdestruction of the piperidine cycle [25] (Scheme 25). The respective hydroxylamine was isolated in the yield of 66.5%. The biradical intermediate 137 either dimerizes to nitroxide 138 or thermolyses via 139 to a nitrogen-free fragment 140 (phorone) and nitric oxide. 

The hydroxylamine used for the reaction with cyclohexanone is obtained by the Raschig process or by catalytic hydrogenation of either nitric oxide or nitric add. In the Raschig process, the hydroxylamine is obtained in the form of its sulfate. The raw materials for this process are sulfur dioxide, ammonia, carbon dioxide, and water. A mixture of NO and NO2, as obtained from the catalytic oxidation of ammonia, is absorbed in an aqueous ammonium carbonate solution to yield ammonium nitrite, which is then reacted with SO2 in the presence of ammonium hydroxide. The product of this reaction is hydroxylamine disulfonate, which converts upon hydrolysis via the monosulfonic acid hydroxylamine into hydroxylamine sulfate ... 

---