Hydroxylamine from oxidation

Figure 34 Oxidative reactions of amines. Formation of N-oxides from oxidation of tertiary amines and formation of hydroxylamines from oxidation of primary and secondary amines.

Most recently, the utility of online HDX-based LC-MS for distinguishing isomeric N-oxides and hydroxylamines from oxidation at carbon was discussed [105], Most often additional information from LC-MS-based HDX such as whether an oxidation is taking place on nitrogen or carbon can be very helpful for further characterization of a metabolite by NMR or narrow down the synthetic routes and save resource and time during the drug discovery and development process [104],... 

In the mechanism study of /V-benzyl-/V -alkyl hydroxylamines, regarding oxidation with HgO and p-benzoquinone, it has been proposed on the basis of intra- and intermolecular kinetic isotope effects that, initially, there takes place a one-electron transfer from a nitrogen atom to the oxidant, with a subsequent proton abstraction (106—108). 

In a similar reaction, 2-(o-nitrophenyl)ethylamine (100) may be reduced in an ammonia buffer to the hydroxylamine and oxidized to the nitroso derivative, which condenses with the amino group to a dihydrocinnoline.160,161 It is also possible to prepare dihydrobenzo-l,2,3-triazinones on reduction of o-nitrobenzhydrazide, followed by oxidation of the hydroxylamine to a nitroso group, and 3-phenyldihydrobenzo-l,2,3-triazine (101) from N-phenyl-(V-(o-nitrobenzyl)hydrazine (100) in an analogous way161 [Eq. (78)]. 

The teichoic acid shows an infrared absorption band at 1751 cm.-1, characteristic of carboxylic ester groups, which is not observed in samples from which the D-alanine residues have been removed. Removal of the u-alanine was readily effected with ammonia or hydroxylamine, when D-alaninamide or D-alanine hydroxamate were formed. The kinetics of the reaction with hydroxylamine reveal the high reactivity of its D-alanine ester linkages, which, like those in most other teichoic acids, are activated by the presence of a neighboring phosphate group. That the D-alanine residue is attached directly to the ribitol residues, instead of to the d-glucosyl substituents, was also shown by oxidation with periodate under controlled conditions of pH, when it was found that the D-alanine residues protect the ribitol residues from oxidation. Under the same conditions, all of the ribitol residues were oxidized in a sample of teichoic acid from which the D-alanine had been removed, and it is concluded that the ester groups are attached to C-2 or C-3 of the ribitol residues. 

Catalytic synthesis of hydroxylamine from nitrogen oxide and hydrogen is widely used in industry as a constituent part of caprolactam production. The reaction is conducted in aqueous sulfuric acid solution saturated with NO and H2 at 40°C and a pressure of approximately 1 atm. Platinum supported on porous graphite, in the form of fine particles suspended in the intensely stirred solution, is used as a catalyst. The main direction of the reaction is... 

Penner, N., Ramanathan, R., Alvarez, N., Chowdhury, S., Alton, K., and Patrick, J. (2003). LC-MS methods for distinguishing hydroxylamine from N-oxide and hydroxy metabolites, In Proceedings of the 51st, ASMS Conference on Mass Spectrometry and Allied Topics, Montreal, Canada. 

I. llosvay s Reagent is prepd in the following manner Dissolve Ig of Cu(NO,). 5H 0 in ca 30ml distd w contained in a 50ml volumetric flask. Add 4ml of coned NH OH soln and 3g of hydroxylamine hydrochloride, NH OH.HCl. Shake until themixt becomes colorless and dilute to volume. If the reagent is protected from oxidation by a layer of mineral oil, or if a piece of Cu wire is added, it will retain its reactivity for a long time. When acetylene or its derivatives are bubbled thru the reagent, red coloration or ppt is produced (Ref X8,p 516)... 

N-oxidation can occur in a number of ways to give either hydroxylamines from primary and secondary amines [Eqs. (11) and (12)], hydroxamic acids from amides, or N-oxides from tertiary amines [Eq. (13)]. The enzyme systems involved are either cytochrome P450 or a flavoprotein oxygenase. Hydroxylamines may be further oxidized to a nitro compound via a nitroso intermediate [Eq. (11)]. Oximes can be formed by rearrangement of the nitroso intermediate or N-hydroxylation of an imine, that could in turn be derived by dehydration of a hydroxylamine [Eq. (11)]. N-Oxides may be formed from both tertiary arylamines and alkylamines and from nitrogen in heterocyclic aromatic systems, such as a pyridine ring. 

A method for the synthesis of optically active hydroxylamines from optically active primary amines with retention of configuration is based on the conversion of the amines to corresponding benzylimines followed by oxidation to 3-phenyloxaziiidines (74). Subsequent hydrolysis leads to hydroxylamines (Scheme 16). This sequence has been extended to the synthesis of optically active N-hydroxy-a-amino acid esters. ... 

Abstraction of hydrogen may also occur from a hydroxylamine being oxidized to a new aminyloxide in this way108,127 ... 

It explodes on heating (and presumably would be formed if distillation of hydroxylamine from calcium oxide were attempted). 

There are a number of important methods worthy of merit for the synthesis of phosphorylglycines. Thus, electrophilic amination of diethyl l-(ethoxycarbonyl)methylphosphonate proceeds in one simple operation via the sodium salt in THF or DME. A variety of aminating agents are used with variable yields, such as 0-mesitylenesulfonylhydroxylamine (39 7%), chloramine (23-84%), and diphenyl (O-hydroxylamine)phosphine oxide (60%). Diethyl 1-ethoxycarbonyl- or l-(tert-butoxycarbonyl)methylphosphonate may also be efficiently transformed into oxime or diazo derivatives and then converted to an amine by a further reduction step. The oximes are prepared from EtONO via the sodium diethyl l-(tert-butoxycarbonyl)methylphosphonate (17% or 36%), from NOCl and diethyl l-(ethoxycarbonyl)methylphosphonate in the presence of tEtOljMg, Al-Hg, or Al(O7-Pr)3, 8 from NOCl and diethyl l-(methoxycarbonyl)ethylphosphonate, ° or from NOCl/ROH and diethyl l-tchlorocarbonyl)mclhy I phosphonate. ... 

Why is so much ferricytochrome c necessary and molecular oxygen unnecessary for the enzymatic oxidation of hydroxylamine to nitrite The author believes that the enzymatic oxidation of hydroxylamine occurs in two steps (see the reaction formulas below). At the first step (3.3), hydroxylamine is oxidized to an intermediate metabolite NOH by losing two hydrogen atoms, and at the second step (3.4), two hydrogen atoms are taken off from NOH and water. For the reactions (3.3) and (3.4), molecular oxygen is unnecessary. Assuming that the reaction (3.3) proceeds much more rapidly than the reaction (3.4), ferricytochrome c is almost exhausted at the reaction (3.3) if the amount of ferricytochrome c added is less than... 

Alcaligenes faecalis has a hydroxylamine-oxidizing enzyme which differs from the enzyme of other heterotrophic nitrifying bacteria. In this bacterium, hydroxylamine is oxidized through pyruvic oxime (Fig. 3.6). Pyruvic acid derived from lactate, succinate, and other carboxylates reacts nonenzymatically with hydroxylamine formed from ammonia to form pyruvic oxime. This compound is oxidized to nitrite and pyruvic acid by the catalysis of pyruvic oxime dioxygenase (Ono et al., 1996, 1999). 

The same author [24] also obtained HN3 from hydrazine and hydroxylamine by oxidation (b + c) ... 

In the analysis, the signal from the working electrode W2, having a potential of - -0.6 V, is used. Here, hydroxylamine is oxidized via a 2-electron reaction ... 

Formation of O, N, A -trisubstituted hydroxylamines from tertiary amine oxides via [1,2]-R group migration, or [2,3]-sigmatropic rearrangement when R = allyl ... 

Secondary arylamines also form hydroxylamines initially, but these invariably oxidise further to the radicals Ar2N and ArgN (O) The diphenylimino radical (At2N) also results from oxidation by non-peroxidic reagents and it exists in equilibrium with its dimer, tetraphenylhydrazine (equation 80) Diaryl nitroxide radicals... 

Without additional reagents Hydroxylamines from N-oxides... 

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