Anilines aniline tetramer

An identical strategy has been used for grafting aniline tetramer [a model compound mimicking the behavior of poly(aniline)] onto 4-formyldithiobenzoate-capped CdSe NCs.113 129 130... 

Polythiophene randomly grafted with alkyl and aniline tetramer groups (157) was synthesized. The tetramer was chosen because it is the minimum oligomer size that mimics the electrochemical behavior of polyaniline, which shows semiconduction and conduction behavior depending on its state of oxidation and the pH. Transition from one structure to the other is illustrated in equation 23, where the electron mobility of quinonoid states (158) rearranging to isolated free radicals (159) is precluded after reduction to 160. A correlation was found between the electrochemical behavior and the UVV-NIR spectra of the 157 polymers255. 

Optical Conductivity Optical Dielectric Function Discussion of Conductivity and Dielectric Functions Microwave Frequency Dielectric Constant Pseudoprotonic Add Doping of Polyanihne Comparison of Doped Aniline Tetramers, Aniline Octamers, and Polyanihne Chiral Metalhc-Doped Polyanihne... 

Comparison of Doped Aniline Tetramers, Aniline Octamers, and Polyaniline... 

These facts are perfectly matched with our above-mentioned desired requirements. In addition, alkyl zinc is known to be less basic and deprotonation of ketone-aniline 36 by zinc reagent is highly unlikely. However, one of the issues for this reaction was the requirement for two alkyl groups on the zinc metal since the product ends up as tetramer 61, where the zinc atom still has one alkyl group, recalling that our cyclopropylacetylene (37) is not easy to obtain. 

Many other aliphatic or aromatic amines produce the same reaction. However if N-alkyl (or aryl)2-aniline is made to react with tris-dimethylaminophosphine, tricoordinated phosphorus compounds are obtained. Their analyses and mass spectra show that they are tetramers (5) when the energy of the ionizing electron beam is nearly 70 eV the mass spectra of the oligomers show an intense [M] peak which corresponds to the monomer ion (n = 1) but when the spectra are obtained by field desorption m.s. the molecular ion peak corresponds to a tetramer (n = 4) one sees also smaller peaks for ions n = 3, 2 or 1. 

Some mo non itro compds, such as o- p-Nitro-aniline, p-Nitrotoluene j and some of their derivs produce orange or red color in dimethylformamide upon the addn of 0.1ml of 10% aqueous soln of tetram ethyl ammonium hydroxide, Janovsky s reagent which is 10% aq NaOH soln may also be used) 22)G.H. Wetter, Development of Instrumentation for Determining the Total Chromaticity and Qiromaticity vs Time of... 

Estimation of the enthalpy of formation of emeraldine can be approached from a different direction. The standard synthetic reaction using aniline and ammonium perdisulfate has been calorimetrically studied63 and shown to be exothermic by —439 5 kJmol-1. Reaction 13 is thus exothermic by —1756 20 kJmol-1 per emeraldine tetramer. 

The monomer/dimer equilibrium may be studied at very low concentrations. The KD value (equation 3) ranges from 0.44 M 1 at 10 °C to 0.26 M 1 at 70 °C, in a concentration range of aniline from 0.03 to 0.2 M. At concentration values of up to 4 M of aniline, the self-association involves monomer, dimer and tetramer species. The tetramer probably exist in a cyclic form. 

The first stage in the production of MDI (9d) is condensation between aniline and formaldehyde, in the presence of HC1, under subatmospheric pressure, at 70-105 °C. This affords 4,4, 2,4 and 2,2 isomers of diaminodiphenylmethane (9a, 9b and 9c). Reaction with phosgene in an inert solvent, such as chlorobenzene, first at low temperature, and then heating to 120 °C, gives, for the 4,4 isomer (9a), MDI, trimers, tetramers and higher oligomers, the latter known as poly-MDI or PMDI. Continuous liquid-phase phosgenation is favored. 

Although Sc(OTf)3 has slightly different properties compared with other lanthanide triflates,the chiral Sc catalyst could be prepared from Sc(OTf)3, (R)-(+)-binaphthol, and a tertiary amine in dichloromethane [76]. The catalyst was also found to be effective in the Diels-Alder reactions of acyl-1,3-oxazolidin-2-ones with dienes. The amines employed in the preparation of the catalyst influenced the enantioselectivities strongly. For example, in the Diels-Alder reaction of 3-(2-butenoyl)-l,3-oxazolidin-2-one with cyclopentadiene (CH2C12, 0°C), the enantiomeric excesses of the endo adduct depended crucially on the amines employed aniline, 14% ee lutidine, 46% ee triethylamine, 51% ee 2,2,6,6-tetram-ethylpiperidine, 51% ee diisopropylethylamine, 69% ee 2,6-dimethylpiperid-ine, 69% ee 1,2,2,6,6-pentamethylpiperidine, 72% ee and cis-1,2,6-trimethyl-piperidine, 84% ee. 

G. Ciric-Marjanovic, M. Trchova, and J. Stejskal, Theoretical study of the oxidative polymerization of aniline with peroxydisulfate Tetramer formation, Int. J. Quantum Chem., 108, 318-333 (2008). 

The electrochemical synthesis was performed in a one-compartment three-electrode cell, in air and without stirring according to the method of Snauwaert and al. The working and counter electrodes are made of ITO glass. The potentials are referred to the Saturated Calomel Electrode (SCE). The synthesis of the polymer was performed at 800 mV vs SCE. Aqueous solutions of distilled aniline (O.I M) and fluoboric acid (HBF41 M) are used. The aniline (Umer is a commercial product, in contrast to the tetramer synthesized as described elsewhere according to the Honzl method. ... 

The Cls Core Level We have first studied the electronic structure of the reduced molecules (dimer, tetramer and polymer) of aniline as a function of the length... 

Yang and coworkers [43,44] modeled the conformation of a tetramer of aniline (with the terminal amine removed) in the EB form (Figure 2.7) to study the possible interactions between the polymer and the secondary amine. The resulting minimized structure shows the expected twist of the aromatic rings along the chain. The distance between the two ortho-hydrogens, next to the imine nitrogen of... 

FIGURE 2.7 Computer model of the EB tetramer showing the two ortho-hydrogens around the imine (above), and the structure of the aniline EB (with the terminal amines removed) (below). (Reprinted from Yang, D., Zuccarello, G., and Mattes, B.R., Macromolecules, 35, 5304, 2002. With permission from the American Chemical Society.)... 

Tetramers of aniline (and substituted anilines) were optimized using the B3LYP functional with a 6-3IG basis set. The unit cell for polymer calculations was built from the tetramer structural data obtained above. In our calculations, a periodical, infinite and non-planar helical geometiy was assumed having the internal coordinates of one aniline unit, as shown in Fig. 2. We have studied the electronic properties of PANI only in its reduced form. Previous works have shown that PANI has a large band gap in the reduced state (around 3.6eV), which diminishes for the oxidized state. These effects were extensively analyzed using VEH and Extended HUckel methods [35]. 

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