Ueber das Phenylhydroxylamin

Bamberger, Eug.

doi:10.1002/cber.18940270276

Cited by 77 publications

(45 citation statements)

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“…Evidence for this mechanism in the present case is the increase in the ratio of the reduction product to the adduct ( [17]: [16] with increased concentration of bromide ion. (1) With both halides, the only product derived from the solvent was 4-aminophenol (2), with 2-aminophenol not detected (<0.5%) in any experiments. With chloride ion present, 4-chloroaniline (19) and 2-chloroaniline (20) were also obtained, in relative yields that were independent of the concentration of the chloride ion: [20]: [19] (23) was also formed.…”

Section: Resultsmentioning

confidence: 80%

“…Bamberger reported 100 years ago that N-phenylhydroxylamine and its derivatives rearrange in aqueous acid solutions to give 4-aminophenols (1). With the parent compound (1) in aqueous sulfuric acid, 4-aminophenol (2) was the exclusive product observed, while both 4-chloroaniline and 2-chloroaniline were also formed with HCl as the acid (1,2).…”

mentioning

confidence: 99%

“…With the parent compound (1) in aqueous sulfuric acid, 4-aminophenol (2) was the exclusive product observed, while both 4-chloroaniline and 2-chloroaniline were also formed with HCl as the acid (1,2). A study by Ingold and co-workers in the 1950s showed that despite the formation of these chloroanilines, the rate was independent of chloride ion concentration (3).…”

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confidence: 99%

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Halide ion trapping of nitrenium ions formed in the Bamberger rearrangement of N-arylhydroxylamines. Lifetime of the parent phenylnitrenium ion in water

Fishbein¹,

McClelland²

1996

Can. J. Chem.

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The acid reactions of five arylhydroxylamines (Ar = 2,6-Me2C6H3, 2,5-Me2C6H3, 2-MeC6H4, 2-C1C6H4, and C6H5) have been studied at constant ionic strength (NaC104) in the presence of varying amounts of NaBr and NaCI. Each system resulted in the corresponding p-aminophenol, the product of Bamberger rearrangement, as the only detectable product in the absence of halide. ' The addition of halide ion reduced the yield of this product, with the appearance of the corresponding p-haloaniline, o-haloaniline (where appropriate), and the parent aniline (predominantly with bromide). Rate constants for the reaction were measured in the case of the parent and 2,6-dimethyl systems and showed small decreases (chloride) or increases (bromide) with increasing halide concentration. These changes did not correlate with the change in products, implying that the rate variations were caused by specific salt effects. Product data were analyzed by a mechanism involving rate-limiting formation of the appropriate arylnitrenium ion followed by product-determining steps involving trapping by the solvent or by the added halide. The possibility that a portion of the halide-trapped products were derived from a pre-association mechanism was also included. Kinetic analyses then produced kBr:kw and kcl:kw ratios for two limiting cases, one involving pre-association with an equilibrium constant K,, = 0.3, and one ignoring pre-association. From an azide:water ratio (kAz:kw) previously determined for the 2,6-dimethylphenylnitrenium, kBr was concluded to lie in the range (4-5) x lo9 M-I s-I for all of the nitrenium ions of this study. This range for kB, then led to k, values of (1-2) x lo9 s-I (2.5-Me2), (2-3) x 10' s-' (2-Me), and (4-8) x lo9 s-' (parent and 2-Cl), where the ranges reflect uncertainties in the exact value of kBr and in the contribution from pre-association. The lifetime of the parent phenylnitrenium ion in water at one molar ionic strength is concluded to lie in the range 125-250 ps.

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Section: Resultsmentioning

confidence: 80%

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confidence: 99%

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confidence: 99%

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Halide ion trapping of nitrenium ions formed in the Bamberger rearrangement of N-arylhydroxylamines. Lifetime of the parent phenylnitrenium ion in water

Fishbein¹,

McClelland²

1996

Can. J. Chem.

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“…A similar process was already observed for the formation of azoxybenzene from solutions of phenyl hydroxylamine upon air oxidation to nitrosobenzene and following condensation with phenylhydroxy lamine to form azoxybenzene. 9 Here, 5 aminotetrazole is oxi dized to 5 hydroxylaminotetrazole and partially further oxidized to 5 nitrosotetrazole, which together with 5 hydroxylaminotetra zole condensates to 5,5′ azoxy bistetrazolate.…”

Section: Resultsmentioning

confidence: 99%

5,5′-Azoxytetrazolates – a new nitrogen-rich dianion and its comparison to 5,5′-azotetrazolate

Fischer¹,

Hüll²,

Klapötke³

et al. 2012

Dalton Trans.

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“…Previous studies have shown that PHA is unstable in solution, being oxidized to PhNO, which then condenses to AzB (10,11,(17)(18)(19). Further investigation has now shown that, in oxygenated aqueous solutions (pH 6.0-7.8), PHA is also oxidized to PhNO2.…”

Section: Resultsmentioning

confidence: 94%

Oxidation of phenylhydroxylamine in aqueous solution: a model for study of the carcinogenic effect of primary aromatic amines.

Becker¹,

Sternson²

1981

Proc. Natl. Acad. Sci. U.S.A.

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Phenyihydroxylamine is degraded in aqueous phosphate buffers at physiological pH values (6.8-7.4) to give nitrosobenzene, nitrobenzene, and azoxybenzene. The reaction is 02 dependent and subject to general acid and general base catalysis. At pH c 5.8 in cacodylate buffer, it is converted to p-nitrosophenol in addition to nitrosobenzene, nitrobenzene, and azoxybenzene. Nitrobenzene and p-nitrosophenol appear to form directly from phenylhydroxylamine. A common intermediate generated from phenylhydroxylamine and 02 is suggested to account for the formation of nitrobenzene, nitrosobenzene, and p-nitrosophenol and is consistent with kinetic studies and '80-labeling experiments. The results suggest that neither hydrogen peroxide nor superoxide (°2) are involved in the oxidation sequence.Arylhydroxylamines (AHs) are formed metabolically by the action of hepatic mixed-function oxidases on primary arylamines (1, 2). These compounds are of considerable interest because, on further reaction, they produce yet-undefined proximal carcinogens. Evidence supporting the involvement of ionic electrophilic species (1-4) and, alternatively, of free radical species (5-7) have been offered to describe the proximal carcinogen.In preliminary in vitro metabolic studies in mammalian liver preparations with various AHs, their high reactivity has been confirmed and shown in large part not to depend on the presence of active enzyme or any proteinaceous material (8, 9). The chemistry ofthe AHs in several nonaqueous systems (10-12) and at pH extremes (13, 14) has been described; however, these transformations are highly medium dependent and cannot be extrapolated to aqueous systems and in addition, these studies were carried out at high concentrations of AH (>10-2 M) (11), at which the 02 concentration is limiting.Therefore, a more intensive investigation of the reactions of AHs in aqueous environments, particularly in the physiologically relevant pH range is warranted. In this report, we describe the chemistry of PHA in aqueous metal-free cacodylate (pH 5.3-6.8) and phosphate (pH 6.3-7.4) buffers. Although it is not a potent carcinogen, PHA was used because, structurally, it is the simplest representative of this class of compounds. MATERIALS AND METHODSNitrosobenzene (PhNO), p-aminophenol (PAP), p-nitrosophenol (PNP), azoxybenzene (AzB), and nitrobenzene (PhNO2) were from Aldrich and purified before use. PHA was synthesized by reduction of PhNO2 with Zn metal (15) and recrystallized from CH2C12/C5Hl2. Because of the reported lability of hydroxylamines in the presence ofheavy metals (11), the buffers were rendered metal free by extraction with dithizone solution (16). 1802 (99 atom %) and H2180 (95 atom %) were from Prochem Isotopes (Summit, NJ).Reactions were carried out in a 250-ml aspirator bottle fitted with a gas dispersion tube to introduce gas mixtures. The vacuum take offwas sealed with a rubber septum and served as a sampling port. Metal-free buffer (50 ml) was introduced into the reaction vessel, which was flushed with argo...

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Ueber das Phenylhydroxylamin

Cited by 77 publications

References 1 publication

Halide ion trapping of nitrenium ions formed in the Bamberger rearrangement of N-arylhydroxylamines. Lifetime of the parent phenylnitrenium ion in water

Halide ion trapping of nitrenium ions formed in the Bamberger rearrangement of N-arylhydroxylamines. Lifetime of the parent phenylnitrenium ion in water

5,5′-Azoxytetrazolates – a new nitrogen-rich dianion and its comparison to 5,5′-azotetrazolate

Oxidation of phenylhydroxylamine in aqueous solution: a model for study of the carcinogenic effect of primary aromatic amines.

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