Anilines charge-transfer complexes

The nitrosonium cation can serve effectively either as an oxidant or as an electrophile towards different aromatic substrates. Thus the electron-rich polynuclear arenes suffer electron transfer with NO+BF to afford stable arene cation radicals (Bandlish and Shine, 1977 Musker et al., 1978). Other activated aromatic compounds such as phenols, anilines and indoles undergo nuclear substitution with nitrosonium species that are usually generated in situ from the treatment of nitrites with acid. It is less well known, but nonetheless experimentally established (Hunziker et al., 1971 Brownstein et al., 1984), that NO+ forms intensely coloured charge-transfer complexes with a wide variety of common arenes (30). For example, benzene, toluene,... 

Torrance obtained a sample that showed ferromagnetic properties with a high Curie temperature by a reaction of 1,3,5-triaminobenzene with iodine under rather drastic conditions (Torrance et al., 1987). A charge-transfer complex of iodine with an aniline-black-type polymer [32], a heteroatom-containing analogue to [14 ] (Johannsen et al., 1989), may have been... 

It is assumed that an excited state charge transfer complex is formed between the nitroaromatic in its first triplet state and the respective substrate. Internal proton transfer is immediately followed by hberation of carbon dioxide. Finally hydrolysis of the hemiacetal Ar —X—CH2OH (X = NH or S) leads to 2-chloro-aniline or thiophenol, respectively. In the decarboxylation of a-phenylthio-acetic acid, some methyl-phenylsulfide is also formed. (7t,7r )-nitroaromatics are more reactive than nitro compounds with lowest (n,7t )-triplets iso). 

Also highly nitrated compounds can be detected and identified by means of donors, such as hydrocarbons. Their identification was suggested by the method of thin-layer chromatography [103]. A method of rapid detection, of explosives such as TNT, TNB, Picryl chloride, wi-DNB, Tetryl in the form of charge-transfer complexes with aromatic amines, such as aniline, dimethylaniline, toluidines, anisidines, naphthylamines, benzidine etc. was developed by Dwivedy et al. [104]. The authors used for identification thin-layer chromatography establishing Rf values for model complexes. 

Ward and Upchurch (340) found an inverse relationship between the solubilities of 18 substituted anilines and their adsorption by nylon (R2 = 0.77) and cellulose triacetate (R = 0.80). It was suggested that steric and electronic effects of the molecules were also responsible for the adsorption differences of the compounds. Because of the low solubilities of the substituted anilines, adsorption by organic matter probably occurs at lipophilic sites through dipole-dipole interactions—e.g., hydrogen bonding or charge-transfer complexes. Low adsorption at clay surfaces probably occurs because the hydrophobic molecules do not readily associate with hydrated surfaces. Adsorption of the substituted anilines by dry clays might occur on the soil surface for instance, but in the... 

The authors also considered the possibility of catalysis by N-methylaniline in alcohol and, in fact, found that a threefold increase in the initial amine concentration resulted in a greater than 29% increase in the second-order rate constant. Nevertheless, they did not consider this change s nificant. It should be noted that n-methyl-aniline would be expected to form a charge-transfer complex with 2,4-dinitrofluorobenzene, that such complexing could result in a decrease in the experimental bimolecular rate constant with increasing initial... 

TNT forms charge-transfer, or 7r, complexes with polycyclic aromatic hydrocarbons, aromatic amines, and aromatic nitro compds a number of these are listed below in Table 2. The complexes with three amines (diphenylamine, diethyl-aniline, p-anisidine) have characteristic colors this forms the basis for a rapid and convenient thin-layer chromatographic analytical procedure (Ref 34) for the identification of very small amounts of TNT. (For a discussion of the many color reactions of TNT, and of composite expls containing it, see Vol 3, C405-L ff)... 

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