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synthesis of p-aminophenol from p-nitrophenol ..

Synthesis of Nitrobenzene and Aniline, 2004 - Erowid

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04/01/2018 · Synthesis of Nitrobenzene and Aniline ..

The fate of nitrobenzene has been studied in a simple model "farm pond" aquatic ecosystem with a six-element food-chain. The system contained phytoplankton and zooplankton, green filamentous algae (), snails (sp.), water fleas (), mosquito larvae () (fourth instar) and mosquito fish (). At the start of the experiment, 300 daphnia, 200 mosquito larvae, 6 snails, strands of algae and miscellaneous plankton were exposed to 14C-labelled nitrobenzene at a concentration of 0.01–0.1 mg/litre. After 24 h, 50 mosquito larvae and 100 daphnia were removed and 3 fish were added. The experiment was terminated after a further 24 h. The ecological magnification index (ratio of the concentration of parent material in the organism to the concentration of parent material in water) was about 8 in mosquito fish after a 24-h exposure. Bioaccumulation from water is not considered significant at these values (Trabalka & Garten, 1982). The ecological magnification index was 0.7 in snails, 0.8 in mosquito larvae, 0.15 in water fleas and 0.03 in green algae. Thus, nitrobenzene remained mainly in the water during the experiment and was neither stored nor ecologically magnified. It was also found to be reduced to aniline in all organisms and acetylated in fish, whereas the mosquito larvae and snails also hydroxylated it to nitrophenols; however, the extent of metabolism was small (Lu & Metcalf, 1975). It should be noted that the ecological magnification index may not be equivalent to a bioconcentration factor (BCF), which usually assumes that equilibrium between water and the organism has been reached.

for there may be a residue of m-dinitrobenzene or higher nitro compounds and an explosion ..

The work cited in the previous paragraph was followed up using radioactive nitrobenzene, leading to the identification of a much greater proportion of the orally administered dose (Parke, 1956). In rabbits given a single dose of randomly labelled [14C]nitrobenzene (200–400 mg/kg of body weight) by stomach tube, 70% of the radioactivity was eliminated from the animals in expired air, urine and faeces within 4–5 days after dosing. The remainder of the radioactivity was found to be slowly excreted in urine and possibly in expired air (as carbon dioxide). Approximately 1% of the dose was found as carbon dioxide and 0.6% as nitrobenzene in expired air within the first 30 h of exposure; the elimination of carbon dioxide was not complete within this time. After 4–5 days, approximately 58% of the dose was eliminated in urine as -aminophenol (31%), -nitrophenol (9%), -nitrophenol (9%), -aminophenol (4%), -aminophenol (3%), 4-nitrocatechol (0.7%), aniline (0.3%) and-nitrophenol (0.1%); two new metabolites, not identified in the studies of Robinson et al. (1951), were nitroquinol (0.1%) and -nitrophenolmercapturic acid (0.3%). Over 4–5 days after dosing, faeces were found to contain around 9% of the administered radioactivity, of which 6% was as -aminophenol. Over this period, including the radioactivity remaining in the tissues and that excreted in urine, faeces and expired air, 85–90% of the dose was accounted for. Traces of radioactivity were still detectable in urine 10 days after dosing (Parke, 1956).

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In a study in which a single guinea-pig was given [14C]nitrobenzene by intraperitoneal injection at 500 mg/kg of body weight (Parke, 1956), the only marked differences in the findings from the results in rabbits (gavage dosing) were the complete absence of -nitrophenol and a decrease in -nitrophenol; it was considered by the author that the - and -nitrophenols may be more readily reduced to the corresponding aminophenols in guinea-pigs than in rabbits.

In the 1950s, air measurements of nitrobenzene in a Hungarian production facility gave 29 mg/m3 (confidence interval 20–38 mg/m3), and the workers showed increased methaemoglobin levels (mean 0.61 g/100 ml, i.e., about 4–5%), some workers even indicating Heinz body formation at about 1% (Pacséri et al., 1958). In a more recent survey in an anthraquinone plant (Harmer et al., 1989), atmospheric nitrobenzene levels over an 8-h period, measured by GC, ranged from 0.7 to 2.2 mg/m3. Small amounts of unchanged nitrobenzene were detected in blood preshift on day 1 (ranging from non-detectable to 52 µg/litre) and postshift on day 3 (ranging from 20 to 110 µg/litre in the same seven workers), indicating some accumulation of nitrobenzene in the body. Methaemoglobin levels were all below 2%, with no clear correlation with blood nitrobenzene levels. Urinary -nitrophenol tended to increase over the 3-day shift period (ranging between about 0.2 and 5.4 mg/litre), although there did not appear to be much correlation with atmospheric concentrations of nitrobenzene. Among many possible factors, the lack of correlation could suggest skin absorption. Urinary - and - nitrophenols were "detected."

Synthesis of p-Aminophenol by Catalytic Hydrogenation …

Rickert et al. (1983) studied the metabolism and excretion of orally administered nitrobenzene in B6C3F1 mice, Fischer-344 rats and Sprague-Dawley (CD) rats. Findings are summarized in Figure 3 (taken from Rickert, 1987). In mice and both rat strains, urinary metabolites were free and conjugated forms of-hydroxyacetanilide, - and -nitrophenol and, in mice only, -aminophenol; Fischer-344 rats excreted these exclusively as sulfate esters, and mice and CD rats, as free compounds, sulfate esters and glucuronides.

Oxidative metabolism proceeded independently of reductive metabolism in this study; however, the rate of oxidative metabolism of nitrobenzene by hepatic microsomes was extremely slow, being about one-tenth that of aniline. The limited role of the mixed-function oxidase activity for nitrobenzene may be a consequence of the uncoupling of cytochrome P-450, resulting in futile redox cycling of the nitro group, with the generation of superoxide anions. Major oxidative metabolites- and -nitrophenol, represented >30% of the dose. Since rates of hepatic and extrahepatic (renal) microsomal metabolism or isolated hepatocyte metabolism did not appear to account for this level of nitrophenol formation, it was not possible to identify the subcellular site(s) of oxidative metabolism. The fact that oxidative metabolism was unaffected by antibiotic treatment indicates that the - and -nitrophenol did not arise from ring hydroxylation of reduced metabolites followed by reoxidation of the nitrogen. Reductive metabolism appears to precede oxidative metabolism, for two reasons. First, since at least 30% of the nitrophenol was excreted in the form, if reduction were secondary to oxidation, it would be expected that some of the reduction products would be in the form, and this was not the case. Second, the sulfated and acetylated nature of the final reduction product implies liver-catalysed final steps following reduction in the gut (Levin & Dent, 1982). An outline of the proposed metabolism is given in Figure 3 above.

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  • 3-Nitrophenol | C6H5NO3 | CID ..

    After the m-nitrophenol has been distilled the flask should be allowed to cool before air is admitted

  • The metabolism of nitrobenzene in male ..

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    Nitrobenzene - Wikipedia

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Synthesis of m-anisidine Synthesis of 4-nitrophenol

Most (97–98%) of the nitrobenzene produced is retained in closed systems for use in synthesizing aniline and substituted nitrobenzenes and anilines (Dorigan & Hushon, 1976; Anonymous, 1987). Yoshida et al. (1988) estimated a loss of 0.1% in the production of nitrobenzene. The loss was thought to be mainly to the water phase. Losses to wastewater have been observed to be 0.09% of production in one plant and 2.0% in another (Dorigan & Hushon, 1976). Patil & Shinde (1989) reported that nitrobenzene was present in the wastewater streams from the washers at an Indian nitrobenzene/aniline production plant. The wastewater from the aniline plant was found to contain 1980 mg nitrobenzene/litre, which corresponds to the limit of water solubility.

1-Ethoxy-4-nitrobenzene (PDF Download Available)

A reversed-phase high-performance liquid chromatographic (HPLC) method was described for the simultaneous determination of urinary metabolites of several aromatic chemicals, including -nitrophenol (formed from nitrobenzene). The proposed method appears suitable for the routine monitoring of workers exposed to these chemicals (Harmer et al., 1989; Astier, 1992).

m-Nitrophenol synthesis - narkive

Dunlap (1981) reported that most of the production of aniline and other substituted nitrobenzenes from nitrobenzene goes into the manufacture of various plastic monomers and polymers (50%) and rubber chemicals (27%), with a smaller proportion into the synthesis of hydroquinones (5%), dyes and intermediates (6%), drugs (3%), pesticides and other specialty items (9%).

Encyclopedia of Chemical Processing and Design

Cultures of several species of were grown at 30 °C with nitrobenzene supplied in the vapour phase above the culture. The bacteria included , , , and several unidentified strains. All the bacteria were known to contain toluene degradative pathways. The cells were harvested and then incubated with nitrobenzene at 30 °C to enable metabolites to be identified. All the strains grew in the presence of nitrobenzene vapour when glucose or arginine were provided as an alternative carbon source, but none grew on nitrobenzene as the sole carbon source. Several metabolites were identified from the various strains, including 3-nitrocatechol, 4-nitrocatechol, -nitrophenol and -nitrophenol, although several strains did not transform nitrobenzene at all. The nitrocatechols were slowly degraded to unidentified metabolites. Results indicate that the nitrobenzene ring is subject to initial attack by both mono- and dioxygenase enzymes (Haigler & Spain, 1991). In contrast to this, Smith & Rosazza (1974) found no phenolic metabolites when nitrobenzene (1000 mg/litre) was incubated at 27 °C for 24–72 h with the following microorganisms with demonstrated aromatic metabolizing ability: , , , , , sp., , , , and .

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