N-Nitrosoamines reduction

N-nitosoamine Reduction The reduction of N-nitrosoamines can occur across either the N-N bond or the N-0 bond. Both reactions ultimately result in the formation of the parent amine and ammonia. 

N-Nitrosoamines are highly versatile substrates for a-lithiation, because while the N=0 group has activating and coordinating properties similar to the carbonyl group, it lacks the carbonyl group s electrophilicity. The nitroso group will direct lithiation even to a tertiary position (90 -> 91), and can be removed by reduction with Raney nickel.60 The drawback is the toxicity of N-nitrosoamines. 

N-Nitrosoamines, decomposition, 741 reduction to hydrazines, 734 Nitrosoanilines, hydrolysis, 680 Nitroso compounds, condensation with amines, 765 oxidation, 751 preparation, 739... 

Dlphenylhydrazlne, (CeH5>2NNH2. Mol. wt. 184.24, m.p. 34.5°. Supplied as the hydrochloride by Eastman. Preparation from diphenylamine by conversion to the N-nitrosoamine and reduction with zinc dust and acetic acid in ethanol. - ... 

Cleavage of N-nitrosoamines. Buck and Ferry purified N-ethyl-m-toluidine by conversion into the N-nitroso derivative and cleavage of this by reduction with stannous chloride. 

Aromatic nitro groups Aromatic rings N-oxides Alkyl hydrazines Alkyl aldehydes N-methyl derivatives Monoalkenes p-Haloethyl mustards N-Chloroamines Alkyl N-nitrosoamines Alkyl esters of either phosphoric or sulfonic adds Aromatic mono- and dialkylamino groups Aromatic azo groups (because of possible reduction to aromatic amines) Aromatic and aliphatic aziridinyl derivatives Aromatic and aliphatic substituted primary alkyl halides Aromatic amines (including their N-hydroxy derivatives and the derived esters Propriolactones and propriosultones Derivatives of urethane (carbamates) Aliphatic and aromatic epoxides... 

Reduction of the N-N bond affords the parent amine and nitrous oxide. Reduction of the N-O bond gives the unsymmetrical hydrazine, which can be further reduced to give the parent amine and ammonia. Because both reaction pathways ultimately result in the formation of the parent amine, it can be difficult to discern the reaction mechanism for reduction. Reduction of N-nitrosoamines to the parent amine is generally considered a detoxification pathway for nitrosoamines however, formation of the hydrazine has been suggested to be a possible pathway for bioactivation (Tatsumi et ah, 1983). 

The existing database concerning the behavior of N-nitrosoamines in reducing environments is somewhat limited. Chemical reduction or reduction using electrochemical means results in mixtures of the hydrazine and the parent amine (Entwistle et ah, 1982). Presumably, reduction of the more polar N-O bond occurs initially in these systems, giving the hydrazine, followed by reduction to the parent amine (Equation 3.33). The reductive metabolism of N-nitrosoamines also has been reported. N-Nitrosodiphenylamine was reduced by guinea pig liver supernatant to give 1,1-diphenylhydrazine (Tatsumi et ah, 1983). The formation of diphenylamine also was observed it was concluded from control studies, however, that its formation was due to an abiotic process. 

The existing data for the reduction of N-nitrosoamines in anaerobic sediments and soils suggests that the aromatic substrates will be much more reactive. For example, N-nitrosodiethylamine and N-nitrosodisopropylamine were found to be very persistent in sediment slurries. In contrast, the reduction of N-nitroso-diphenylamine was quite fast (t,/2 = 1-5 days), resulting in the formation of diphenylamine (Weber, 1988). Formation of the intermediate, 1,1-diphenylhydrazine, was not observed. Several N-nitrosodialkylamines also have been found to be very persistent in flooded soils and microbial enrichments from bog sediments (Tate and Alexander, 1975). 

Entwistle, I. D., R. A. W. Johnstone and A. H. Wilby. 1982. Rapid reduction of N-nitrosoamines to N,N-disubstituted hydrazines the utility of some low-valent titanium reagents. Tetrahedron, 38(3) 419-423. 

The reduction of Fe(III) porphyrin hydroxides by the heterocyclic aromatic amines, pyridine, 1-methylimidazole, and derivatives takes place in toluene to give the bis-amine Fe(II) porphyrin complexes. The preliminary data suggest that the initial step is formation of a bis-amine Fe(III) complex. Electrochemical oxidation of [Os(II)(terpy)(bpy)(NH3)](PF6)2 in the presence of Et2NH or morpholine yielded bound nitrosoamine complexes, [Os(II)(terpy) (bpy)(N(0)NR2)]. The kinetics and stoichiometry of the reaction between... 

Certain species of Enterobacteriaceae, especially 0. proteus, could utilise nitrates as electron acceptors for anaerobic respiration, resulting in reduction of nitrate into nitrite. Nitrite further could possibly react with secondary amines present in the wort, forming (V-nitrosoamine (Figure 8.2). A -nitrosomines are carcinogenic in nature (Smith, 1994). Hence, a considerable amount of apparent total N-nitroso compounds (ATNCs) represents a possible risk to health, and consequently their concentration is strictly monitored and limited to 20 gg/1 (Maiguerite and Walker, 2002). Because of the risk of W-nitroso compounds, the Enterobacteriaceae species related to brewery environments are monitored. 

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