Aniline, formation properties

The ionic radius or the electrostatic potential (e/r) is often used as the measure of the polarizing power of the cations (2, 3, 6). For example, Broiisted acidity has a good correlation with these properties (3). The correlation between the catalytic activity in the aniline formation reaction and either ionic radius or electrostatic potential was very poor. 

Phenylhydrazine on exposure to light slowly darkens and eventually becomes deep red in colour salts of the base share this property but to a lesser degree, the sulphate and acetate (of the common salts) being most stable to light. Phenylhydrazine is largely used in organic chemistry to characterise aldehydes and ketones as their phenyl-hydrazones (pp. 342, 345), and carbohydrates as their osazones (pp. 136-140). It is readily reduced thus in the process of osazone formation some of the phenylhydrazine is reduced to aniline and ammonia. On the... 

Numerous aromatic nitro compounds have explosive properties, and thus it is important to understand the role that enthalpy of formation has on the sensitivity and long-term stability of these compounds. We will examine three nitro-substituted aromatic families for which thermochemical data can be found in the literature2,84 derivatives of nitrobenzene, aniline and toluene. The choice of these three families allows us to compare the various electronic effects exerted by the parent functional group. The parent compounds differ electronically with respect to the aromatic ring in that ... 

This article deals with the chemistry of carbazoles, and except for their formation from carbazoles as illustrations of the chemistry of carbazoles, it specifically excludes that of 1,2,3,4-tetrahydro-, 1,2,3,4,4a,9a-hexahydro-, 1,2,3,4,5,6,7,8-octahydro carbazoles, etc., because from the viewpoint of chemical reactivity, these are indoles, anilines, pyrroles, and so on. This article also excludes carbazoles with additional fused aromatic or heteroaromatic rings, again except for the formation of such systems as illustrations of carbazole reactivity. The physical and spectroscopic properties are not covered. 

Nitroaromatic compounds (NACs) are one of the widespread contaminants in the environments. Sources of NACs are numerous they originate from insecticides, herbicides, explosives, pharmaceuticals, feedstock, and chemicals for dyes (Agrawal and Tratnyek, 1996). Under anaerobic conditions, the dominant action is nitro reduction by zero-valent iron to the amine. Other pathways do exist, such as the formation of azo and azoxy compounds, which is followed by the reduction of azo compounds to form amines. Also, in addition to the possibility of azo and azoxy compounds, phenylhydrox-ylamine may be an additional intermediate (Agrawal and Tratnyek, 1996). Nitrobenzene reduction forms the amine aniline. Known for its corrosion inhibition properties, aniline cannot be further reduced by iron. Additionally, it interferes with the mass transport of the contaminant to the surface of the iron. The overall reaction is as follows ... 

The palladium-catalyzed formation of diarylamines has been used in several contexts to form molecules of biological relevance. The ability to prepare haloarenes selectively by an ortfio-metalation-halogenation sequence allows the selective delivery of an amino group to a substituted aromatic structure. Snieckus has used directed metalation to form aryl halides that were subsequently allowed to react with anilines to form diarylamines (Eq. (34)) [209]. Frost and Mendonqa have reported an iterative strategy to prepare, by the palladium-catalyzed chemistry, amides and sulfonamides that may act as peptidomimetics. Diaryl-amine units were constructed using the DPPF-ligated palladium catalysts, and the products were then acylated or sulfonated with 4-bromobenzoyl or arylsulfonyl chlorides [210]. Le-miere has coupled primary arylamines with 4-chloro-3(2H)-pyridazinones to form compounds with possible analgesic and antiinflammatory properties. 

Many synthetic methods have been developed for the preparation of quinolines and 1,2,3,4-tetrahydroquinolines due to the interesting biological properties of quinoline-type alkaloids. Most of the synthetic methods are based on the elaboration of aniline derivatives and, as for the synthesis of tetrahydroquinolines, reduction of the corresponding quinolines is the main approach. Only a few methods have been reported for the construction of the quinoline skeleton by N-C(8a) bond formation as the key step, such as oxidative cyclization of 2-(3-aminopropyl)benzene-1,4-diol 89 with K2[Fe(CN)e] (Scheme 42)... 

There are a few alternative approaches to imide copolymers that allow the resin producer to make imide-modified high heat ABS without incurring the cost of the synthesized imide monomer. One is by reacting styrene-maleic anhydrides with a primary amine, either during the polymerization reaction with styrene or in a separate step. Mitsubishi Monsanto has practiced imidiza-tion on a commercial scale and described a process which follows the formation of S-MA with addition of amine and AN [60]. They described the manufacture of maleimide copolymers by heating the SMA copolymers with aniline in an extruder [61]. The maleimidation of the anhydride function is not complete, as there is unreacted amine or maleic anhydride in the product. The polymer stability and physical properties depend on the mole percent of maleimidation. 

Colorimetric Methods. The most frequently used colorimetric methods have been recently reviewed by Omaye et al. (5). Several methods of analyses are based upon the fact that ascorbic acid and dehydroascorbic acid possess certain chemical properties characteristic of sugars such as formation of osazones and conversion to furfural. Colorimetric determination of furfural, an aniline derivative, has been used to a limited extent for the estimation of ascorbic acid in certain materials. These methods have generally been found to be unsatisfactory... 

Certain facts render it doubtful whether the auxochromic amido-groiips enter into combination with the acid radical in the formation of salts, and it is possible that the azo-group enters into combination. Amidoazobenzene, a weak base, retains its basic properties after acetylation, and forms red salts as before while the simple amines such as aniline, which possess much stronger basic properties, yield on acetylation almost completely indifferent compounds. At any rate this fact strongly supports the assumption that there is a certain linkage between the azo- and amido-groups. 

An interesting reaction in which emeraldine is formed was observed by Caro [16]. If aqueous solution of free aniline is oxidised with potassium permanganate, and filtered from the separated manganese dioxide, the filtrate is a yellowish liquid, from which ether takes up a yellow amorphous eompound. This latter is converted into a green salt of emeraldine by mere contact with acids. A substance possessing the properties of emeraldine is formed simultaneously with quinone by oxidation of paramido-diphenylamine. A larger yield is obtained if this base is oxidised with an equivalent of aniline, and in this case quinone is not formed [17]. On further oxidation emeraldine yields a darker coloured compound, but it is doubtful if this is aniline black. The formation of emeraldine from paraphenylenediamine and diphenylamine leads to the supposition that it is a phenylated indamiue of the formula ... 

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