Hydroxylamine synthesis

Concentrations are controlled to yield a molten oxime product layer and a saturated (ca 40 wt %) ammonium sulfate solution ca 125% (theoretical) ammonium sulfate or 2.9 kg/kg caprolactam is produced as a result of side reactions in the hydroxylamine synthesis. 

Catalytic oxidation of ammonia to nitric oxide is the basis of production of nitric acid. It is also used in other processes, of which may be mentioned hydroxylamine synthesis (Section XIII) and the chamber process for the production of sulfuric acid. The products of the reaction are nitric oxide, water, and nitrogen, so that the reaction can be described by the equation... 

ZI N N E R Hydroxylamine Synthesis Synthesis of O-substituted hydroxylamines from oximes or hydroxamates. 

The DRS UV-Vis spectra reported in Figure 8 provide an explanation in the role of Ti center in the hydroxylamine synthesis as well as in the reaction sequence shown in the figure TiS (spectrum 1) reacts with hydrogen peroxide in aqueous solution generating a hydroperoxo species (spectrum 2, complex 2) the addition of ammonia produces a mixed ammonia-hydroperoxo species (spectrum 3, complex 3). In time, ammonia is oxidized to hydroxylamine restoring the Ti center. Spectrum 4 shows the final step of tiie catalytic reaction (7). 

In our early studies we avoided the issue by preparing short peptide fragments and converting the N-terminus to the hydroxylamine by a variation of Fukuyama s outstanding method (Scheme 12) [27, 28]. This was effective but not convenient. Following our first publication, we returned to the problem of peptide hydroxylamine synthesis. 

Takeo and Lei showed that it was indeed possible to use our methods for a-ketoacid and hydroxylamine synthesis to prepare several cyclic peptide namral products [34, 35]. No post-cyclization manipulatimis other than purification were required. The ability to perform the cyclization on unprotected side chains may... 

Sosnovskikh VY, Mel nikov MY, Pogozhikh SA (1999) Reactions of 3,3-dialkyl-2,3-dihydro-6-trifluoromethyl-4-pyrones with hydroxylamine. Synthesis tmd structures of 5-( 1, l-ditdkvl-2-hydroxyethyl)-5-hydroxy-3-trilluoromethyl-AMsoxazoUnes. Russ Chem BuU 48 1323-1328... 

Sosnovskikh VY, Moshkin VS, Kodess MI (2008) Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine synthesis of novel R -containing isoxazole and chromone derivatives. Tetrahedron 64 7877-7889... 

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