Photonitration

Photochemical activation of [ESE, TNM] complexes. Colored solutions of the ESE derived from the relatively unreactive cycloalkanones and acyclic ketones in Table 2 and TNM persist for prolonged periods, and they can thus be separately subjected to filtered actinic radiation with /exc > 420 nm. (Note that under these conditions, neither TNM nor ESE alone is excited since they absorb only below 400 nm.) The photonitrations of ESE with TNM are carried out at low temperatures (—40°C) at which the thermal reactions are too slow to... 

Nelieu S, Shankar MV, Kerhoas L, Einhorn J. Phototransformation of monuron induced by nitrate and nitrite ions in water Contribution of photonitration. J Photochem Pho-tobiol A Chem 2008 193 1-9. 

Keywords Induced photooxidation Nitrate ion Nitrite ion Photonitration Photonitrosation... 

Phenol transforms in the presence of nitrate and nitrite under UV irradiation. In all cases of oxidation/hydroxylation, nitrosation and nitration products have been detected. The oxidation and hydroxylation of phenol is initiated by reaction with hydroxyl, while nitrosation is probably due to reaction with N2O3. The formation of 2- and 4-nitrophenol from phenol is a consequence of the reaction of the substrate with nitrogen dioxide ( NO2/N2O4), although the details of the mechanism are still uncertain. It is, however, very doubtful that phenol photonitration involves phenoxyl as an intermediate, since nitra-... 

The role of aromatic photonitration and photonitrosation processes in natural waters is still not clearly understood. It is, however, very interesting to report that nitration and nitrosation of monolinuron have been observed upon photolysis of nitrate and nitrite at environmental concentration levels [144], Studies on the environmental importance of such reactions will indeed benefit from the use of HPLC-MS-MS techniques for both process studies and field analysis, as they allow much lower detection limits to be reached when compared with traditional HPLC techniques. In the case of process studies, it would be very interesting to determine the extent at which the pathways observed for the photonitration and photonitrosation of aromatic compounds at fairly high concentration levels can be extrapolated to environmental conditions. 

The photolysis of nitrate in surface waters and of nitrite in atmospheric hydrometeors is a relevant source of hydroxyl, while the assessment of the environmental importance of nitration and nitrosation processes needs further studies. Recent results, however, indicate that photonitration and photonitro-sation might play a more important role in the environment than previously suspected [144], All such processes are influenced by substrate and ion concentration and in some cases by the amount of dissolved organic matter. 

The conversion of naphthalene to 2-naphthoic acids by irradiation with carbon dioxide and electron donors (e.g. amines or dimethoxybenzene) has been further investigated and the quantum yields of the reaction measured for different solvents and donors. Electron transfer also occurs in the photochemical phosphonation of naphthalene and phenanthrene achieved by irradiation with trialkyl-phosphites and electron acceptors such as 1,3-dicyanobenzene. The photonitration of phenol in aqueous solutions of nitrate ion has been reported and phenols have been prepared by irradiation of substituted benzenes with the aromatic N-oxide (132). ... 

Nitration with nitrogen dioxide in the presence of sulphuric acid Nitration with nitrogen dioxide in the presence of Friedcl-Crafts catalysts Nitration with nitrogen dioxide in the presence of activated silica Photonitration with nitrogen dioxide Nitrogen Pentoxide (Nitric anhydride)... 

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