Derivatives nitro compounds

Harvey DG. 1953. The toxicity of the dinitro-cresols Part II The formation and toxic properties of some nitro compounds derived from meta-and para-cresols. J Pharm Pharmacol 5 497-510. 

A number of aromatic nitro compounds, derivatives of benzene, toluene, xylenes, mesitylene and durene have been investigated by proton resonance spectra [37-41]. The nitro group was found to shift the aromatic proton resonance signals to low fields from that of benzene in the order ortho > para > meta. 

By reaction in benzene of P 3aromatic nitro compounds, derivatives such as <1) and <3) reacts with Ru3ruthenium nitrene complex <5) reaction with excess nitrobenzene in boiling benzene [653. On the other hand even the thermal disproportionation of <5) (M=sRu R=Ph) under an inert atmosphere and in solution leads to the formation of <1), and other as yet uncharacterised products[663. Complexes following sequence of reactions]603s... 

It should be noted that only representative substances are indicated in the above list. Substituted derivatives of the compounds in most classes may be encountered, e.g., nitrobenzoic acid in the aromatic carboxylic acids (p. 347). This acid will contain CH(0)N, but the salient properties are still those of a carboxylic acid, CH(0), Section 14, although the properties of an aromatic nitro-compound (e.g.y reduction to an amino-compound) will also be evident. 

Oxidation of side chains. Aromatic nitro compounds that contain a side chain (e.g., nitro derivatives of alkyl benzenes) may be oxidised to the corresponding acids either by alkahne potassium permanganate (Section IV,9, 6) or, preferably, with a sodium dichromate - sulphuric acid mixture in which medium the nitro compound is more soluble. 

Secondary nitro compound dark blue or blue green colour due to nitro-iiitroso derivatives. The coloured compound is soluble in chloroform. 

Dilute sodium hydroxide solution. Carboxylic acids (RCOOH), sulphonic acids (RSO3H), phenols (ArOH), thiophenols (ArSH), mer-captans (RSH), imides (RCONHCOR), aryl sulphonamides (AxSOjNHj), arylsulphonyl derivatives of primary amines (AxSOjNHR), oximes (RCH=NOH), primary and secondary nitro compounds (RCH=NOOH and RjC=NOOH-oci forms), and some enols (e.g., of 1 3-diketones... 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

Little is known quantitatively about substituent effects in the nitration of derivatives of azanaphthalenes. In preparative experiments 4-hydroxy-quinoline, -cinnoline, and -quinazoline give the 6- and 8-nitro compounds, but with nitric acid alone 4-hydroxyquinoline and 2,4-di-hydroxyquinoline react at With nitric acid, 4-hydroxycinnoline... 

The 2-benzamido 4-aryl(alkyl)selenazoles (96) form the corresponding 5-nitro derivatives under mild conditions using the nitrate-sulfuric acid method (Scheme 31). The nitro compounds are well-defined, ciy s-talline compounds. They may be most favorably obtained by dissolving the 2-benzamidoselenazoles in acetone and adding concentrated nitric... 

However, prior protective acetylation of the amino group leads to a good yield of the 5-nitro compound [2-acetamido-4-methyl-5-nitroselenazole, m.p. 185 C (19)j. Similarly. 2-diethylamino-4-methy)-selenazole with nitric acid gives the. 5-nitro derivative [vellow needles, m.p. 93°C (26)],... 

Nitrobenzene was first synthesized in 1834 by treating benzene with fuming nitric acid (1), and was first produced commercially in England in 1856 (2). The relative ease of aromatic nitration has contributed significantly to the large and varied industrial appHcations of nitrobenzene, other aromatic nitro compounds, and their derivatives. 

Nitration. Direct nitration of aromatic amines with nitric acid is not a satisfactory method, because the amino group is susceptible to oxidation. The amino group can be protected by acetylation, and the acetylamino derivative is then used in the nitration step. Nitration of acetanilide in sulfuric acid yields the 4-nitro compound that is hydroly2ed to -rutroaruline [100-01-6]. 

A -Heterocyclic-A -acetylsulfanilamides. These derivatives may be prepared by condensation of the heterocycUc amine with /)-nitroben2enesu1fony1 chloride foUowed by acetylation of the nitro compound. The product may be reduced under mild conditions to give the 4-amiQO-A/ -heterocychc-A/ -acetyl derivative. Other approaches, however, have been developed (46,47). 

However, the preparation of l-nitroanthraquiQone-2-carboxyhc acid has the difficulties mentioned previously. Therefore, new processes for preparing this compound not from the 1-nitro compound but from other precursors have been iatensively studied. 1-Amin oanthra quin one derivatives have been proposed for this purpose (90). 

Hydroxyaminopyridazine 1-oxides are usually formed by catalytic hydrogenation of the corresponding nitro derivatives over palladium-charcoal in methanol, provided that the reaction is stopped after absorption of two moles of hydrogen. 3-Hydroxyaminopyridazine 1-oxide and 6-amino-4-hydroxyamino-3-methoxypyridazine 1-oxide are prepared in this way, while 5-hydroxyamino-3-methylpyridazine 2-oxide and 5-hydroxyamino-6-methoxy-3-methylpyridazine 2-oxide are obtained by chemical reduction of the corresponding nitro compounds with phenylhydrazine. 

Nitration of a series of methyl-1,2-benzisoxazoles was studied by Tahkar and Bhawal using fuming nitric acid and sulfuric acid in acetic acid at 100 °C. 3-Methyl-1,2-benzisoxazole gave a mixture of 5-nitro- and 5,7-dinitro-3-methyl-l,2-benzisoxazole, with the 5-nitro isomer predominant. The product obtained from 3,5-dimethyl-1,2-benzisoxazole was the 4-nitro derivative and not the 7-nitro compound as proposed by Lindemann (26LA(449)63). The synthesis of the 7-nitro compound by an alternative method was used as structural proof. Two products were obtained from 3,6-dimethyl-l,2-benzisoxazole and these were the 5-nitro and 5,7-dinitro derivatives. 3,7-Dimethyl-l,2-benzisoxazole was converted into the 5-nitro derivative (Scheme 25) (77lJC(B)l06l). 

Three selective methods to remove protective groups are receiving much attention assisted, electrolytic, and photolytic removal. Four examples illustrate assisted removal of a protective group. A stable allyl group can be converted to a labile vinyl ether group (eq. 4) a /3-haloethoxy (eq. 5) or a /3-silylethoxy (eq. 6) derivative is cleaved by attack at the /3-substituent and a stable o-nitro-phenyl derivative can be reduced to the o-amino compound, which undergoes cleavage by nucleophilic displacement (eq. 7) ° ... 

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