Aromatic-amine interaction

Dioxygen is a weak oxidant. Nevertheless, phenols and aromatic amines interact with dioxygen at elevated temperatures according to the reaction [23,31,32,38,52]... 

The aromatic-amine interaction is modeled as the interaction between C6H6 and H2NCH3. In this work, only the ar-type hydrogen bonding structures are considered. In this structure, the amine should reside over the benzene ring with one of its amine hydrogens pointing toward its aromatic it electrons (Fig. 12). 

FIGURE 21. Numerous macrocycles based on salicylideneamino alcohols, arising from (a and b) aliphatic and (c and d) aromatic amines, interacting with aryl boronic acids have been identified, (e) Analogous semianhydride bridged structures have also been observed. 

NMR signals of the amino acid ligand that are induced by the ring current of the diamine ligand" ". From the temperature dependence of the stability constants of a number of ternary palladium complexes involving dipeptides and aromatic amines, the arene - arene interaction enthalpies and entropies have been determined" ". It turned out that the interaction is generally enthalpy-driven and counteracted by entropy. Yamauchi et al. hold a charge transfer interaction responsible for this effect. 

In the presence of proton-donative organic solvents (alcohols), aliphatic amines do not react with diazonium, whereas aromatic amines form mainly triazenes and also para-aminoazo compounds, which subsequently interact slowly with an excess of diazo reagent via N-coupling and form disazo derivatives. 

In the presence of aprotonic organic solvents, both aromatic and aliphatic amines interact with 4-nitrophenyldiazonium in the same way. The first stage yields fast in corresponding triazenes. At the second stage, irrespective of initial amine nature, triazenes interact with an excess of diazo reagent and fonu l,3-bis(4-nitrophenyl)-triazene. Triazenes of aliphatic amines transform fast as well. In case of aromatic amines, the second stage yield depends on the inductive constants of substituents in an azo component. 

When primary aromatic amines are treated with nitrous acid, diazonium salts are formed. The reaction also occurs with aliphatic primary amines, but aliphatic diazonium ions are extremely unstable, even in solution (see p. 448). Aromatic diazonium ions are more stable, because of the resonance interaction between the nitrogens and the ring ... 

Aromatic amine-Ketone. The interaction between anihne, the simplest of the aromatic amines with acetone in the presence of various catalysts to yield N-isopropylaniline was examined (Table 17.3). Among the catalysts tested, sulfided platinum catalysts were found to be the most active catalysts for this reaction. 

Gennaro, M. C., Bertolo, P. L., and Marengo, E., Determination of aromatic amines at trace levels by ion interaction reagent reversed-phase high-performance liquid chromatography. Analysis of hair dyes and other water-soluble... 

The results obtained with different amines cannot be explained merely on the effects of amine basicity. Thus, to obtain complete hydrogenation of Q to DHQ, the basicity has to be tailored by other factors such as the steric hindrance of the amine and its electronic interaction with the catalyst active sites this seems to be favored by the presence of an electron-rich aromatic ring. Of note, the positive effect of substituted aromatic amines, with a 49% DHQ yield being obtained for ethylanilines, is independent of the substituent position of the alkyl group. 

An interaction of both additives and formation of a new component, which then acts as a more efficient stabilizer. Example aromatic amines + mercaptobenzimidazol. 

The synergistic action of a phenol and aromatic amine mixture on hydrocarbon oxidation was found by Karpukhina et al. [16]. A synergistic effect of binary mixtures of some phenols and aromatic amines in oxidizing hydrocarbon is related to the interaction of inhibitors and their radicals [16-26]. In the case of a combined addition of phenyl-A-2-naphthylamine and 2,6-bis(l,l-dimethylethyl)phenol to oxidizing ethylbenzene (v, = const, 343 K), the consumption of amine begins only after the phenol has been exhausted [16], in spite of the fact that peroxyl radicals interact with amine more rapidly than with phenol (7c7 (amine) = 1.3 x 105 and /c7 (phenol) = 1.3 x 104 L mol 1 s respectively 333 K). This phenomenon can be explained in terms of the fast equilibrium reaction [27-30] ... 

Substitution patterns, especially that of the diazotized aromatic amine, determine the color of a pigment to some extent but empirical data do not lead to unambiguous conclusions as to the exact influence of a particular substituent on the shade. The problem is intricate, since the substitution pattern also has a bearing on the size and orientation of a pigment molecule and therefore on its crystal structure, including all the interactions associated with it. 

In principle, aliphatic amines may interact as n electron donor molecules towards electron acceptor centres such as aromatic substrates, both homocyclic and heterocyclic, containing electron-withdrawing groups, usually nitro groups. These interactions are mainly electron donor-acceptor (EDA) interactions, in which aromatic amines are considered n or/and tt electron donors. 

The preliminary electronic interaction seems to be required since, if the first mercury atom is absent, a trans addition takes place. Furthermore, a possible important role of the basicity of the nitrogen has been underlined taking into account that aminomercuration of 1,4- and 1,5-hexadienes with aromatic amines leads mainly to the trans isomer. 

Then, contrary to our previous hypothesis, the reaction proceeds via a Bai2 displacement of aniline on DMC. The product, mono-A -methyl aniline (PhNHMe), plausibly adsorbs into the zeohte in a different way with respect to anihne, because different H-bonds (N H — O-zeolite) take place with the solid. As recently reported by Su et al., A-methyl amines also may interact with NaY by H-bonding between the protons of the methyl group and the oxygen atoms of the zeolite this probably forces the molecule a bit far from the catalytic surface in a fashion less apt to meet DMC and react with it. This behavior can account for the mono-A-methyl selectivity observed, which is specific to the use of DMC in the presence of alkali metal exchanged faujasites in fact, the bis-A-methylation of primary aromatic amines occurs easily with conventional methylating agents (i.e., dimethyl sulfate). ... 

Because primary aromatic amines are weaker bases/nucleophiles than aliphatic (due to interaction of the electron pair on N with the n orbital system of the aromatic nucleus), a fairly powerful nitrosating agent is required, and the reaction is thus carried out at relatively high acidity. Sufficient equilibrium concentration of unprotonated... 

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