Oxidations of organonitrogens

Oxidation of organonitrogen compounds is an important process from both industrial and synthetic viewpoints . N-oxides are obtained by oxidation of tertiary amines (equation 52), which in some cases may undergo further reactions like Cope elimination and Meisenheimer rearrangement . The oxygenation products of secondary amines are generally hydroxylamines, nitroxides and nitrones (equation 53), while oxidation of primary amines usually afforded oxime, nitro, nitroso derivatives and azo and azoxy compounds through coupling, as shown in Scheme 17. Product composition depends on the oxidant, catalyst and reaction conditions employed. 

This family of organonitrogen pesticides includes the nitrophenols and their salts, for example, Dinoseb and the substituted dinitroanilines, trifluralin, and nitralin. Figure 3 shows a typical commercial process for the production of a dinitroaniline herbicide [8]. In this example, a chloroaromatic is charged to a nitrator with cyclic acid and fuming nitric acid. The crude product is then cooled to settle out spent acid, which can be recovered and recycled. Oxides of nitrogen... 

Introduction of a silyl group at the position a to the nitrogen decreases the oxidation potentials of organonitrogen compounds by at most 0.3 V (Table 7)31. fi- and y-silyl groups do not cause a significant decrease in the oxidation potential. The introduction of a silyl group directly on the amino nitrogen atom does not decrease the oxidation potentials of amines. 

Oxidations. Potassium ferrate(VI) supported on clay has been used in the oxidation of alcohols to carbonyl compounds, of thiols to disulfides, and of organonitrogen compounds. Another method for oxidizing alcohols involves acyl nitrates absorbed in days. ... 

Hypervalent iodine(III) compounds have found wide application for the oxidation of organic derivatives of nitrogen, sulfur, selenium, tellurium and other elements. Reactions of X -iodanes with organonitrogen compounds leading to the electron-deficient nitrenium intermediates and followed by cyclizations and rearrangements (e.g., Hofmann rearrangement) are discussed in Section 3.1.13. Several other examples of oxidations at a nitrogen center are shown below in Schemes 3.168-3.170. 

Oxidative reactions of organonitrogen species that do not involve molecular oxygen are rather limited. The only case for which the evidence is at all convincing is the oxidation of arylhydroxylamines to arylnitroso species (Table 2). This reaction resembles the first half of the hydroxylamine oxidoreductase reaction found in nitrifying bacteria. The key difference is that the aryl nitroso compound is stable (although condensation with the arylhydroxy-lamine can occur to produce the azoxy compound, ArN(O)NAr), while the inorganic analog is nitroxyl, HNO, which if released from the enzyme would rapidly dimerize and dehydrate to form N2O. Consequently, HAO does not release the HNO or NO intermediate, but instead oxidizes it to nitrite before any substrate-derived species are released. 

We took advantage of the property of different solvents to extract selectively the tetravalent actinide and lanthanide elements. Some of them are sufficiently stable in the presence of oxidizing agents. Among the organonitrogen and organophosphorus compounds we used were tri-laurylmethylammonium (TLMA) salts and tributyl phosphate (TBP) in carbon tetrachloride. 

Organonitrogen oxidation. A very wide variety of nitrogen oxidations are of industrial importance, some of which are already carried out using clean oxidation systems. In this section, the types of oxidation will be briefly reviewed. Since most amines give alkaline pH in aqueous systems, it is common to add stabilisers when using H2O2. 

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