Nitrobenzene derivatives

Phenazine mono-N-oxides have also been prepared from nitrobenzene derivatives. Condensation of nitrobenzene with aniline using dry NaOH at 120-130 °C results in modest yields of phenazine 5-oxide, although the precise mechanism of this reaction is not well understood (57HC(ll)l) with unsymmetrical substrates it is not possible to predict which of the isomeric fV-oxides will be produced. Nitrosobenzene derivatives also function as a source of phenazine mono-fV-oxides thus, if 4-chloronitrosobenzene is treated with sulfuric acid in acetic acid at 20 °C the fV-oxide is formed (Scheme 21). 

The reaction of ap- or o-nitrobenzene derivative with a nucleophilic reagent is generally first order with respect to each reactant and follows a bimolecular course according to Eq. (1). The reaction is then formally similar to the corresponding change at a saturated carbon ( Sj 2 ... 

Data related to the piperidino-dechlorination of o- and p-nitrobenzene derivatives appear in refs. 67 and 68 for the reactions in non-polar solvents and in refs. 69 and 70 for the reactions in alcohols. 

In agreement with the assumption of a nucleophilic bimolecular reaction, increased electron deficiency at the site of the displacement causes acceleration and vice versa. The reaction is very sensitive to substituent effects, in accordance with what is found with nitrobenzene derivatives and what is generally expected for a nuclear... 

The usual order found with halogenonitrobenzenes is F > Cl Br I, the order of Cl and Br being variable, just as in heteroaromatic reactivity. The position of fluorine is of interest the available data indicate that it is usually the same as for nitrobenzene derivatives. Thus, in acid hydrolysis the order F > Cl for 2-halogeno-quinolines can be deduced beyond doubt since the fluoro derivative appears to react in the non-protonated form and the chloro derivative to resist hydrolytic attack even in the protonated form under appropriate conditions (Section II,D, l,d). Furthermore, in the benzo-thiazole ring, fluorine is displaced by the CHgO reagent at a rate 10 times that for chlorine. ... 

The effect of other substituents and of the nucleophilic reagent on ortho vs. para reactivity in nitrobenzene derivatives has been discussed... 

TABLE 32.2 Standard Gibbs Energy of Transfer and Standard Ion Transfer Potentials for Ion Transfer Between Water and Nitrobenzene Derived from Partition Measurements... 

Allylation of the nitro group on nitrobenzene derivatives proceeded under similar reaction conditions (Eq. 11.36).64 Allylation reactions of various benzoylhydrazones with tetraallyltin were carried out in... 

The zinc teflate Zn(OTeF5)2 has been synthesized and characterized by IR and 19F NMR spectroscopy. The interaction with a number of weakly coordinating solvents was studied and the single-crystal X-ray structures determined for nitrobenzene derivatives [Zn(OTeF5)2 (PhN02)2]2 and Zn(0TeF5)2(PhN02)3.428... 

The ortho/para orientation rule of ground state chemistry appears to be followed in the photosubstitution reactions of nitrobenzene derivatives in liquid ammoniaa40) ... 

Nitro compounds have also been reported to undergo photocyclizations. The intermediacy of an isoxazoline in the photorearrangement of o-nitro-benzaldehyde to o-nitrosobenzoic acid is now in doubt,318 but intramolecular hydrogen abstraction by an excited nitro group in nitrobenzene derivatives can result in the formation of heterocycles. 4-tm-Butyl-3-methoxy-2,6-dinitrotoluene (384) on irradiation in methanolic sodium hydroxide solution... 

Data for some nitrobenzene derivatives in DMSO and cyclohexane are collected50 in Table 12. 

Because the difference in the shieldings between the two solvents for one nitrobenzene derivative is constant at almost 4.5 ppm, there is no evidence of any serious influence of substituents on the range and direction of solvent-induced variation in the shielding of the aromatic nitro group. 

This procedure illustrates a general method for converting substituted pyrylium salts to nitrobenzene derivatives. The reaction has been the subject of several reviews. - The yields are generally high, and under these conditions only a single product is formed, in contrast to the nitration of 1,3,5-triphenyl-benzene. The preparation of 2,4,6-triphenylnitrobenzene from the corresponding pyrylium salt eliminates isomer separation problems, which are encountered when the direct nitration procedure is used. Also, labeled compounds can readily be prepared by this method. ... 

Shimizu N, Yasui Y, Matsumoto N. 1983. Structural specificity of aromatic compounds with special reference to mutagenic activity in Salmonella typhimurium - a series of chloro- or fluoro-nitrobenzene derivatives. Mutat Res 116 217-238. 

Deneer JW, Sinnige TL, Seinen W. 1987. Quantitative structure-activity relationships for the toxicity and bioconcentration factor of nitrobenzene derivatives towards the guppy (Poecilia reticulata). Aquat Toxicol 10 115-129. 

Shimizu M, Yano E. 1986. Mutagenicity of mono-nitrobenzene derivatives in the Ames test and rec assay. Mutat Res 170 11-22. 

Stemmler EA, Hites RA. 1987. The electron capture negative ion mass spectra of 2,6-dinitroaniline and 2,4-dinitrophenol herbicides and related nitrobenzene derivatives. Biomed Environ Mass Spectrom 14 417-434. 

Chloramphenicol (Chloromycetin) is a nitrobenzene derivative that affects protein synthesis by binding to the 50S ribosomal subunit and preventing peptide bond formation. It prevents the attachment of the amino acid end of aminoacyl-tRNA to the A site, hence the association of peptidyltransferase with the amino acid substrate. Resistance due to changes in the ribosomebinding site results in a decreased affinity for the drug, decreased permeability, and plasmids that code for enzymes that degrade the antibiotic. 

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