Migration nitro groups

Efforts directed to prepare MDP2P via this method results in good yields of a ketone with properties completely dissimilar to MDP2P, and is probably the propiophenone, formed by migration of the nitro group during the hydrolysis. 

Substituted aromatics, eg, aLkylbenzenes, sometimes experience attack at the substituent position by NO/ (7). A cyclohexadienyl cation is formed it is unstable and the nitro group migrates on the ring to a carbon atom that is attached to a hydrogen. Loss of the proton results in a stable nitroaromatic. 

Tables 11 and 12 list the currently available non-laked monoazo yellow and orange pigments. Most of them carry a nitro substituent in the diazonium component, usually in ortho position relative to the azo bridge. The more migration-resistant Pigment Yellow 97 lacks a nitro group in its molecule. Seven monoazo yellow pigments are based on 2-nitro-4-chloroaniline or derivatives as a diazo component.

Substituted 2-nitroanilines also rearrange in concentrated sulphuric acid at 110°C to give both products of rearrangement 72 and 73, where again 1,3-nitro group migration occurs81. 

Tanaka et al. (2000) reported that N02 nitration of 1,8-dimethylnaphthalene leads to 2-nitro and 4-nitro products. For 2-nitro prodnct, the reaction proceeds as electrophilic substitution—the nitro group comes into the ipso position and then migrates to the position 2, thus giving the final product. For 4-nitro product, the process develops according to electron-transfer ronte. The spin density of 1,8-dimethylnaphthalene cation-radical is highest at position 4 (or, the same, at position 5). It is the para nitration that takes place in the experiment. 

Several recent studies have shown the ease of oxygen migration to tin, OH groups from hydroxylic ligands 235) [Eq. (29)] as well as oxygen from nitro groups becoming bonded to tin (79) ... 

However, for an apparent 0-3 to 0-2 migration of a nitro group during the alkaline methanolysis of methyl 4,6-O-benzylidene-a-D-glucopyranoside 3-nitrate, see J. Honeyman and J. W. W. Morgan,/. Chem. Soc., (1955) 3660-3674. 

The nitro group does not undergo migration of the naphthalene ring during the usual nitration procedures. Therefore, mono- and polynitration of naphthalene is similar to low temperature sulfonation, The nitronaphthalenes and some of their physical properties arc listed in fable 2. Many of these compounds are not accessible by direct nitration of naphthalene but are made by indirect methods, e.g nitrite displacement of diazonium halide groups in the presence of a copper catalysts, decarboxylation of nitronaphtbalcnccar-boxylic acids, or deamination of nitronaphthalene amines. They are nsed in the manufacture of chemicals, dye intermediates, and colorants for plastics. 

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