P-Nitroanisole

Anisole. The simultaneous (homolytic and nucleophilic) annihilations of AN+ as described by the time-resolved spectroscopic results lead to the distinctive mixtures of o- and p-nitroanisoles, in which the isomeric composition is strongly dependent on the nitrating reagent in the following way. 

When o-, m- and p-nitroanisole with 14C-labelled at the methoxy group were irradiated under identical conditions in methanol in the presence of sodium methoxide, only m-nitroanisole underwent methoxy exchange, with the limiting quantum yield (

labelled isotope experiments support a a complex intermediate and indicate an Sjv23Ar mechanism (direct substitution in the triplet state) for this reaction (equation 12) and for 4-nitroveratroles (equation 13). Further evidence from quenching and lifetime experiments also support a direct displacement SAr2Ar mechanism for the photosubstitution reaction of nitroaryl ethers with hydroxide ions13. 

The effect of an o-methyl substituent on the photosubstitution of o- and p-nitroanisole by hydroxide ions28 (equations 24-26) can be ascribed to both electronic and steric effects that determine the reactivity and selectivity. 

Hz for the ortho, meta and/or para coupling constants of p-nitroanisole, two dinitrotoluenes and 2,4-dinitrochlorobenzene. Both reports indicate that other aromatic compounds investigated showed even less solvent dependence. 

Hutton, H. M., Schaefer, T. Solvent Dependence of Chemical Shift and Coupling Constants in p-nitroanisole. Can. J. Chem. 43, 3116 (1965). 

Monooxygenase Assays. Incubation media contained the following (final concentrations) 0.05M phosphate buffer, pH 7.A, glucose-6-phosphate (G-6-P, 2.3 mM), G-6-P dehydrogenase (3 units), NADP (0.23 mM), and KC1 (2.8 mM), and various tissue preparations. Substrates were added in small volumes (25 yl or less) of MeOH. Samples (1.1 ml) were shaken in a thermostated (usually at 22°C) water bath and reactions terminated by enzyme denaturation. Specific analytical procedures for aldrin epoxi-dation (13), 1 CH30-p-nitroanisole 0-demethylation (1A), and 3H-benzo(a)pyrene oxidation (15) have been described. 

Chemicals. Antipyrine, carbon monoxide (Matheson, Coleman and Bell, Los Angeles, CA), and 1 CH3-N-antipyrine (11.1 mCi/mM, ICN, Irvine, CA) were purchased. Aldrin (1,8,9,10,11,11-hexa-chloro-2,3-7,6-endo-2,1-7,8-exo-tetracyclo (6.2.1.13,6.02 7) dodeca-A,9-diene) and its epoxide, dieldrin were gifts of Shell Development Co. (Modesto, CA). Each was recrystallized from methanol-water solutions and was greater than 99% pure as determined by gas chromatography. l CH30-p-Nitroanisole (1.9 mCi/mmole) was synthesized (1A) and 3H-benzo(a)pyrene (8.3 Ci/ mmole) was purchased (Amersham-Searle Co., Arlington Heights,... 

Three sets of experiments have been done to determine the effect of environmental variables on antipyrine disposition. The conditions included 1) animals transferred to either Instant Ocean or ocean gater antipyrine solutions, 2) animals maintained in Instant Ocean in the laboratory for periods up to 31 days, 3) mussels placed into antipyrine solutions which contained low levels of other foreign compounds (aldrin, p-nitroanisole, SKF 525-A). Results are summarized in Tables IV and V. 

Antipyrine uptake and elimination was also assessed in the presence of aldrin and p-nitroanisole, among substrates used in biotransformation studies (Table V). Altered antipyrine half-lives might indicate that the levels of the substrates were stressful to the mussels. The levels used did not overtly effect the mussels pumping activity, and half-lives were within the range of control values. Antipyrine disposition measurements will be included in studies on the biological fate of chemicals. 

Effect of Aldrin, p-Nitroanisole, and SKF 525A on Uptake and Elimination of Antipyrine by Mussels... 

Similarly, in vivo metabolism of p-nitroanisole has been demonstrated by formation of a more polar, unidentified metabolite revealed following extraction and TLC (Benzene MeOH, 95 5, Silica gel G, 0.25 mm). Indication of in vitro anisole metabolism has also been obtained, but the nature of metabolites is uncertain. For the present, these observations are con-... 

Biochemical studies with mussel tissue homogenates and microsomal fractions have been conducted using viscera (whole mussel minus adductor muscles), green gland, gill, and mantle. Using aerobic conditions and an NADPH-generating system, the metabolism of aldrin and p-nitroanisole have been observed. 

A competition between substitution and two kinds of quenching processes, either dependent or independent on the added nucleophile, is envisaged for the photosubstitutions of p-nitroanisole (pNA) ni.ns). With cyanide ions in aqueous aerated solution pNA is transformed on irradiation into 2-cyano-4-nitroanisole in high yield ns,ii8) probably via addition of cyanide to excited pNA. 

The catalytic reduction of nitro groups is usually achieved using heterogeneous catalysts, although the iridium complex 28 has been shown to be effective for the reduction of p-nitroanisole 29 to the corresponding aniline 30 using isopropanol as the hydrogen donor (Scheme 8) [30]. In the reduction of some nitroarenes, azo compounds (Ar-N=N-Ar) could be formed as by-products or as the major product by variation of the reaction conditions. 

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