Nitrogen atoms, copolymerization

Poly[(aniline-2-chloroaniline)-4-toluenesulfonic acid salt] was obtained by oxidative copolymerization of aniline with 2-chloroaniline in solutions containing 4-toluenesulfonic acid. The copolymer salt was subjected to heat treatment under nitrogen atmosphere at elevated (about 150°C) temperatures. The heat-treated samples acquired electric conductivity of 2.7 X 10 f2 cm . According to ESR spectra, the heated poly[(aniline-2-chloroaniline)-4-toluenesulfonic salt] exists as the poly(semiquinone imine ion-radical) in which unpaired electrons are localized on or near the nitrogen atoms (Palaniappan 1997). 

Colestipol Colestipol (20.1.1) is a hydrochloride of the product of copolymerization of epichlorohydrine with diethylentriamine that contains varying numbers of quaternary nitrogen atoms. There is no exact formula of the product of copolymerization, but its approximate structure can be expressed as 20.1.1 [1 ]. 

All authors accept the alternating incorporation of epoxide and anhydride into the macromolecular chain 36 39.40.45 52.73-74). However, the mechanisms of termination and chain transfer have not yet been elucidated. Although the lability of the nitrogen atom is obvious 39 40 44> and its salts or associates are readily thermally decomposed 89), Fischer 39 detected its presence in precipitated polyesters by elemental analysis. A simple calculation confirms the presence of the nitrogen atom in almost every tenth macromolecule. In this case, the isolated polyester might be a living polymer and, on the addition of monomers, it might initiate another copolymerization. Similar experiments have not been reported so far. 

Initiation involves the reaction of the tertiary amine (the most widely used Lewis base) with an epoxy group, giving rise to a zwitterion that contains a quaternary nitrogen atom and an alkoxide anion. The alkoxide reacts at a very fast rate with an anhydride group, leading to a species containing a carboxylate anion as the active center. This ammonium salt can be considered as the initiator of the chainwise copolymerization. 

Tertiary amine-functionalized olefins are not difficult to polymerize and copolymerize with group IV catalysts, provided that sufficient steric hindrance is present around the nitrogen atom. Amines of sufficient bulkiness, including diisopropyl and diphenyl derivatives, can be polymerized without the necessity of protection by Lewis-acid complexation. Smaller monomers (such as dimethyl and diethylamines) can be polymerized if 1 equiv of a proper alkylaluminum protecting group is used (vide infra). However, if the amine functionality is too near to the double bond, the additional steric bulk provided by the aluminum species may actually inhibit monomer coordination and polymerization. 

The NHC were chosen as supporting ligands as a result of comparisons with previously described catalytic systems based on dicationic phosphine or sterically encumbered P-diimine. The phosphine and p-diimine systems prevent chain transfer and termination processes. By analogy, it was speculated that mutually c/s-chelating NHC, stabilized by sterically demanding aryl substituents, would help promote the copolymerization of ethylene and carbon monoxide. Unfortunately, mesityl substituents on nitrogen atoms were the only... 

Silica gel-supported, cyclized polyacrylonitrile metal complexes as well as PMAA-Pd and PMAA-Pt complexes were prepared by copolymerization of MAA and a mixture of m- and p-DVB in the presence of silica gel [131]. The catalytic activity of the obtained complexes was examined in the reaction of cumene and ethylbenzene hydrogenation [131] and in the hydrogenation of aromatic and aliphatic nitrocompounds, alkenes and aliphatic aldehydes. Based on the decrease in the bond energy of Cu2p3/2 from 935 to 932.4 eV and the increase in the bond energy of Ajs from 399 to 399.6 eV, it was found, by XPS, that Cu is bound to a complex through a nitrogen atom of PAN. 

The copolymerization of the monomers listed in Table 22-6 proceeds similarly to alternating copolymers with the monomeric units given. But with the polymerization of acrylamide, the polymerization does not proceed, as in the case of initiation with strong bases, via the nitrogen atom to the j8-alanine monomeric unit [see Equation (18-9)], but via the oxygen atom to iminoether structures. 

XPS was also used [108] to study the role of a bromine oxidant in the chemical copolymerization with respect to the amount of bromine incorporated and its interaction with the copolymer. The results of this study shows a direct correlation between electrical conductivity and the concentration of positively charged N atoms along the polymer chain. In addition, there is some bromine substitution on the ring. About 20-33% of the total Br is incorporated as covalent bromide and there is evidence to suggest that a higher Br ion content is found in more conducting polymers, which accounts for the more extensive oxidation of the nitrogen atom. 

Ring-Opening Copolymerization of Some Cyclic Compoimds Containing Oxygen and Nitrogen Atoms... 

An interesting electron-deficient heterocycle, pyrido[3,4-b]pyr-azine (PP), was also copolymerized with BDT unit (P29) by Wei et al.[76] (Figure 3.6). Compared with the quinoxaline in P16, the extra electron-withdrawing nitrogen atom in the PP unit would... 

For ethylene/CO copolymerization, cis-bidentate ligands are widely used examples are (un) substituted DPPP, diimines, or (un) substituted bipyridines and unsymmetrical bidentate ligands represented as phosphine-Z where Z is either neutral or anionic oxygen atom, sp -neutral nitrogen atom, or sulfide. Details for each ligand are described as follows. 

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