Oxidation carbonylative polycondensation

Aromatic polycarbonates are currently manufactured either by the interfacial polycondensation of the sodium salt of diphenols such as bisphenol A with phosgene (Reaction 1, Scheme 22) or by transesterification of diphenyl carbonate (DPC) with diphenols in the presence of homogeneous catalysts (Reaction 2, Scheme 22). DPC is made by the oxidative carbonylation of dimethyl carbonate. If DPC can be made from cyclic carbonates by transesterification with solid catalysts, then an environmentally friendlier route to polycarbonates using C02 (instead of COCl2/CO) can be established. Transesterifications are catalyzed by a variety of materials K2C03, KOH, Mg-containing smectites, and oxides supported on silica (250). Recently, Ma et al. (251) reported the transesterification of dimethyl oxalate with phenol catalyzed by Sn-TS-1 samples calcined at various temperatures. The activity was related to the weak Lewis acidity of Sn-TS-1 (251). 

Polyethers are obtained from three different classes of monomers, namely, carbonyl compounds, cyclic ethers, and phenols. They are manufactured by a variety of polymerization processes, such as polymerization (polyacetal), ring-opening polymerization (polyethylene oxide, polyprophylene oxide, and epoxy resins), oxidative coupling (Polyphenylene oxide), and polycondensation (polysulfone). 

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] ... 

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 presence of quinones in coal and oxidized coals and the products of the reaction of the latter with bisdiazonium compounds have also received some attention. An absorption band at 1640 cm-, observed in the spectra of model compounds obtained from the polycondensation of phenanthrene, pyrene, and chrysene with formaldehyde and subsequent pyrolysis and nitric acid oxidation, was also assigned to nonchelated quinoid carbonyl groups. This band was absent from the spectra of coal, oxidized coals and their products after reaction with bisdiazonium compounds after pyrolysis and oxidation with nitric acid. 

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