Polycondensation, oxidative

On the other hand, polyphenol consisting of oxyphenylene units, PPO, was successfully synthesized by the highly regioselective oxidative polycon- 

Not only phenol derivatives but also 1,4-dialkoxybenzenes undergo oxidative polycondensation to give poly(p-phenylene). However, the oxidative 

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Reactions of the Methyl Groups. These reactions include oxidation, polycondensation, and ammoxidation. PX can be oxidized to both terephthahc acid and dimethyl terephthalate, which ate then condensed with ethylene glycol to form polyesters. Oxidation of OX yields phthaUc anhydride, which is used in the production of esters. These ate used as plasticizers for synthetic polymers. MX is oxidized to isophthaUc acid, which is also converted to esters and eventually used in plasticizers and resins (see Phthalic acids and otherbenzenepolycarboxylic acids). 

The carbonylation oxidative polycondensation of bisphenol, 2,2-bis(4-hydroxyphenyl)propane, with transition metal-based catalysts, which yields the respective aromatic polycarbonate, is of high potential interest [6] ... 

Also of interest is the oxidative polycondensation of 2,6-disubstituted phenols with transition metal catalysts such as palladium complexes, which produces aromatic polyethers [2]. 

As stated above, the carbonylation oxidative polycondensation of bisphenol in the presence of transition metal-based catalysts leads to aromatic polycarbonate [scheme (18)] [6]. The reaction of bisphenol (HOArOH, e.g. Ar = p-C6H4 CMe2—C6H4—), carried out under CO and O2 pressure in a chlorohydrocarbon solvent under anhydrous conditions, using a group 8 metal-based catalyst (e.g. a PdBr2 complex) and a redox catalyst (e.g. Mn(II) (benzoinoxime)2, L vMn) in the presence of a base (e.g. 2,2,6,6,N-pentamethylpiperidine, R3N), involves most probably the pathway shown schematically below ... 

The arrangement of metal atoms at appropriate distances in the polymer backbone (type C) is achieved by the application of either the polymerization method or a combination of monomers. In the backbone of Pt-D1 and Pt-D2 polymers, for example, platinum atoms are regularly arranged at intervals of approximately 7.7 A and 12.1 A, respectively (Table 5). In the polymers prepared by the oxidative polycondensation method (Eq. 13), the metal atoms are arranged at intervals of approximately twice the distance compared with that formed in the dehydrohalogenation reaction (Eqs. 11 and 12). 

Hattori, T. Kijima, M. Shirakawa, H. Oxidative polycondensation of acetylene by iodine in the presence of palladium-copper catalyst. Synth. Met. 1997, 84, 357-358. 

The samples of PAn and PAn/nano-Ti02- S composites were produced by aniline oxidative polycondensation in the presence of sodium per-oxydisulfate as an oxidant in the 0.5 M aqueous HCl solution under the temperature 2 0.5°C. Aniline molar ratio was 1 1.1. During... 

Polyphenylene oxide (PPO) ru A thermoplastic, linear, non-crystalline polyether obtained by the oxidative polycondensation on 2,6-dimethylphenol in the presence of a copper-amine complex catalyst. The resin has a wide useful temperature range, from below —170 to +190°C, with intermittent use to 205° C possible. It has excellent electrical properties, unusual resistance to acids and bases, and is pro-cessable on conventional extrusion and injection-molding equipment. Because of its high coat PPO is also marketed in the form of polystyrene blends (see Noryf ) that are lower-softening (Tg of PS is about 100°C vs 208°C for PPO), and have working properties intermediate between those of the two resins. 

The research on the reaction mechanism of the oxidative polycondensation of 2,6-dimethylphenol (DMP) was also continued in the years around 1990. In several publications a Dutch research group reported on kinetic studies dedicated to the 02-promo ted polycondensation of DMP catalyzed by copper tetramethyl 1,2-diamino-ethane complexes [233-236] or by copper complexes of imidazole [237,238]. The speculative mechanistic scheme was based on dimeric copper complexes such as (147a) which were assumed to incorporate a DMP anion (147b) which was oxidized to yield a phenoxy cation and to coordinate another DMP molecule (148a). The growing step was then assumed to consist of a nucleophilic substitution at the phenoxy cation (149) with liberation of a reduced dimeric copper complex (148b). This complex was believed to be... 

Only those polymers containing ether functional group are considered as aromatic polyethers. The most important is the polymer obtained by the oxidizing polycondensation of 2,6-dimethylphenol... 

Three methods were described for syntheses of hb polymers via formation of Si-O bonds. Kakimoto et al. [108, 109] transformed the stable precursor (a). Formula 11.13, into the reactive intermediate (b), which yielded a hb polysiloxane under elimination of diethylamine. Two research groups prepared hb poly(eth-oxysilane)s from commercial tetraethoxysilane via unstable abs intermediates [110, 111]. HB Si-polyesters were also prepared, namely by oxidative polycondensation of monomer (c). Formula 11.13. 

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