Dimerization aniline

Because of the lower stability of Se(IV) compounds as compared with their Te(IV) analogues (95UK527), the reaction of the disilyldiimine with SeCU ends up in phenanthro[9,10-c]-l,2,5-selenadiazole. 3,4-(2,4-Di-terr-butylbenzo)-l,2,5-telluradiazole 75 was obtained by a treatment of the tellurium diimide 76 with a lithium salt of tris(rerr-butyl)aniline. Dimer 77 is an intermediate in this reaction (96IC9). 

Figure 5-20. Geometrical Nlrucuiris of llic X>ly aniline model compounds PC2 (reduced phenyl-capped aniline dimer amino eompoimd) and PC2QX (oxidi/ed phenyl-capped aniline dimer, imino eoin x>uiul).

There also has been one successful attempt at determining the absolute configuration through analysis of exciton coupling. This was reported by Barnett, Drake and Mason in a study of calycanthine in which CPL in the k —> k spectral region was interpreted in terms of aniline dimers [38]. These authors compared their result to the previously published crystal structure. 

Recently25, some new tools have offered very important supports to infrared spectroscopy, as reported in the following instances. The infrared depletion spectrum of the aniline dimer, formed in a supersonic jet, indicates44,45 that two NH2 groups are equivalent. One possible structure is a sandwich, with the N—H n hydrogen bonds, with two aniline molecules arranged head to tail, as shown in 1. 

The probable structures of aniline dimer cation are calculated by the ab initio MO method 113 shows the N—hydrogen bond and 114 the N—H - N hydrogen bond. Spectroscopic data indicate that the structure 113 seems to be preferred, and ab initio MO calculations support this conclusion182. 

MeTpMs has been synthesized by Dias and Wang as T1 salt.202 The copper complex [CuCl(MeTpMs)] has been employed to polymerize cleanly the aniline dimer, A-(4-aminophenyl)aniline under mild conditions to obtain polyaniline.203 [Ag(CO)(MeTpMs)], [Ag(C2H4)(MeTpMs)] and [Tl(MeTprBu)] have been also described and characterized.204... 

Crochet F, Malval J-P, Lapouyade R. New fluoroionophores from aniline dimer derivatives a variation of cation signaling mechanism with the number of amino groups. JCS Chem Commun 2000 289-90. 

We conclude this section by stating that both mechanisms, i.e., radical cation-radical cation and nitrene-anilinc coupling reactions, may be operative for the aniline dimerization reaction. As pointed out by Genies et al. [49], the nilrene mechanism may be... 

Recently, this difficulty was overcome when the starting diazonium was the aniline dimer (4-aminodiphenylamine or ADPA) [157]. In that case the grafted layer is electro-active and aniline oxidation remains possible in aqueous sulfuric acid and leads to a strongly adherent PANI film on the modified surface. The first experiments were performed on carbon and extension to an oxidizable metal has not yet been reported. However, as it has been proven that the covalent grafting of diazonium salts was also successful with iron and other oxidizable metals [178-182], we think that the same procedure might be applied in the case of iron. A strong increase of the adhesion should be expected, and therefore an improvement of the protection properties. 

Acetaldehyde Acetophenone Adipic acid Aniline Anthranilic acid Benzoguanamine 3,3, 4,4 -Benzophenone tetracarboxylic dianhydride 1,2,4-Butanetriol n-Butyraldehyde Caprolactam Ceteareth-30 Citric acid Dicyclopentadiene Diethyl aniline Dimer acid N,N-Dimethylaniline Dodecenylsuccinic anhydride Epichlorohydrin Ethylene dichloride Formaldehyde Furfural Hexahydrophthalic anhydride Hexamethylene glycol ... 

Obviously, STFM is a facile and efficient approach to synthesize polymer, in particular PANI, nanostructures because it not only omits hard template and post-treatment of template removal but also simplifies reagents. However, the self-assembly mechanism of the conductive nanotubes of PANI by the STFM is not yet understood. It might be due to the formation of aniline dimer cation radicals which could act as effective surfactants to shape the polyaniline morphology. 

Attempts to form surface-confined poly(aniline) have previously been made using 4-aminothiophenol on Au. After oxidation of the monolayer and successive potential scans, this monolayer was found to produce a surface-confined redox active film. Recently, elucidation of the coupling and degradation pathways of this molecule on Au was reported. Radical-radical coupling was found to occur between adjacent aminothiophenol molecules yielding an electrode surface modified with 4 -mercapto-4-aminodiphenylamine. Upon potential scanning of the surface-confined aniline dimer, an electrochemical-chemical-electrochemical (ECE) reaction was found to occur. Oxidation of the quinonediimine resulted in hydrolysis of the dimer to yield a quinone monoimine species. Further oxidation of this molecule then produced the initial 4-aminothiophenol molecule as well as benzoquinone in solution. 

The aniline dimer PPDA plays a similar role as the chain initiator in a classical chain polymerization. Therefore, the amount of PPDA added to the aniline polymerization should significantly affect the molecular weight of polymers. Indeed, we have found that the molecular weight decreases as the amount of PPDA is increased (Fig. 1). At 20 mol-% PPDA, the number-average molecular weight (Mn)... 

Figure 36. TG profile of polydichlorophosphazene with pendant aniline dimer groups, for the polymer (continuous line) and the dimer (dotted line)...

There was a long debate concerning health hazards for polyaniline because of the formation of benzidine, a carcinogenic aniline dimer. Several companies have now succeeded in manufacturing polyaniline and its close rival polypyrrole, and both polymers have been approved by American and European health authorities. ... 

Nonetheless, electrochemical reactions of the analytes under study in an ES-MS experiment can and do take place, and these reactions can substantially alter the analytes such that the ions observed in the gas phase have a different mass and/or charge than the species originally in the solution (Table 3.3). Many fundamental smdies of the electrochemical processes in ES have made use of analytes that are relatively easy to oxidize/ reduce and have both stable oxidized and reduced forms that differ in mass, each of which can be detected in the gas phase by ES-MS. Some compounds of this type that we have used include various metalloporphyrins, aniline dimers, the dyes thionine and methylene blue, and the drug reserpine. >>>>>> The ability to observe both the starting material and the redox products with compounds of this type enhances the abUity to smdy the electrochemical reactions that occur. These same molecules and those others with similar redox character are potentially those that can be altered unexpectedly in an ES-MS experiment. 

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