Chromium -, poly

Again, as with pyridopyrimidines, the main reaction is oxidation of di- or poly-hydro derivatives to fully aromatic structures, often merely by air or oxygen. In some cases the reagent of choice is mercury(II) oxide, whilst other reagents used include sulfur, bromine, chloranil, chromium trioxide-acetic acid, hydrogen peroxide, and potassium ferricyanide, which also caused oxidative removal of a benzyl group in the transformation (306) (307)... 

Small quantities can be distilled at about 75°C/1.3 mbar, but larger amounts are liable to explode violently owing to local overheating [1], An attempt to prepare an analogous poly(dimethylsilyl) chromate by heating a polydimethylsiloxane with chromium trioxide at 140°C exploded violently after 20min at this temperature [2], See related alkylsilanes, metal oxides... 

The metals sulfides are the most dangerous since after aerobic weathering they are transformed into water-soluble sulfates of different metals. Accordingly, in the areas of non-ferrous and rare metal ore exploration and treatments, the acid sulfate landscapes are formed with high content of toxic metals. The biogeochemical technogenic provinces are known, for instance, copper-nickel provinces in the Kola Peninsula, Fennoscandia molybdenum provinces in the Caucasian region, copper and chromium-nickel ones in the South Ural, poly-metal ones, in the Pacific coast of eastern Eurasia (Russia, China, and Korea), etc. 

The -complexes formed between chromium(O), vanadium(O) or other transition metals, and mono- or poly-fluorobenzene show extreme sensitivity to heat and are... 

On zinc phosphate conversion coatings, the "Mannich" derivatives of poly-4-vinylphenol have demonstrated performance equivalent to chromic chromate systems in salt spray, humidity, and physical testing. In addition. Table III illustrates results observed with automotive body paint systems evaluated by the "scab" or "cycle" test which causes failure more typical of actual end use conditions than do salt spray evaluations. Again, results equivalent to chromic-chromate post-treatments were obtained. In addition, the humidity resistance and adhesion tests were essentially equivalent to the chromium controls. 

Dipyridine chromium(VI) oxide, 52,5 DIRECT lODINATION OF POLY-... 

Caesium selenide, 4265 Calcium poly sulfide, 3942 Calcium sulfide, 3941 Cerium trisulfide, 3967 Chromium(II) sulfide, 4245 Cobalt(II) sulfide, 4218 Copper iron(II) sulfide, 4269 Copper(II) sulfide, 4285 Europium(II) sulfide, 4293... 

We have utilized somewhat less-effective optional approaches to copolymer purification with attendant catalyst recovery. One of these methods involved the replacement of the f-butyl substituents on the 5-position of the phenolate ligands with poly(isobutylene) (PIB) groups, as illustrated in Fig. 14 [39]. Importantly, this chromium(III) catalyst exhibited nearly identical activity as its 3,5-di-t-butyl analog for the copolymerization of cyclohexene oxide and carbon dioxide. The PIB substituents on the (salen)CrCl catalysts provide high solubility in heptanes once the copolymer is separated from the metal center by a weak acid. 

Diarene metals generally decompose under conditions of normal electrophilic substitution, but dibenzene chromium can be metalated with amyl sodium in alkanes, and subsequent reaction with carbon dioxide and dimethyl sulfate results in a complex mixture of mono-, di-, and poly-substituted dibenzene chromium methyl esters. It is interesting that these polysubstituted compounds are homoannular in contrast to the corresponding ferrocene compounds. In view of the scanty evidence and ease of oxidation, it is impossible to conclude whether the diarene metals are less aromatic than the dicyclopentadienyl metals as predicted by simple theory (Sec. III.A). 

Thermal spray processes can he used to give coatings of chromium carbide or nickel chromium lor erosion resistance, cupper nickel indium for I retting resistance, tungsten carbide cobalt lor wear and abrasion resistance, and even aluminum silicon poly ester mixtures for abradability. 

Tris(acetylacetonato) chromium has been shown to be of interest as a smoke retarder for poly(vinyl chloride)5 and it augments the inhibition of polyene oxidation by organic phosphites.29... 

Gebhard and Killmann measured the thickness of the adsorbed layer and the adsorbance for poly(methyl methacrylate) adsorbed onto a high-vaccum vapored chromium plate and a platinum plate from theta solvents 1-chlorobutane and acetonitrile. Both quantities increased with rising molecular weight, but the average concentration of adsorbed poly(methyl methacrylate) decreased with molecular weight. The thickness of the adsorbed layer was not proportional to the square root of M. 

Killmann and Wiegand77) investigated the adsorption of poly(ethyiene glycol) and poly(vinyl pyrrolidone) on a chromium plate from water and methanol solutions. The value of tnns for poly(ethylene glycol) (Mw = 40 x 103) in water came dose to the root-mean-square end-to-end distance of the sample in bulk solution, whereas t for polyethylene glycol) (M = 6.13 x 103) in water and that for poly(vinyl pyrrolidone) (Mw = 38 X 103) in water or methanol were much larger than those in bulk solutions. No comparison between theory and experiment was made. 

Poly(2-vinylpyridine) or poly(4-vinylpyridine) supported chromium... 

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