Iron-based oxidants

Iron-based oxide mixtures, e.g. ferrites, and supported iron oxides can be very effective catalysts for the dehydrogenation of butene to butadiene, as also appears from the patent literature [160],... 

THE REDOX PROCESS USING IRON BASES OXIDE MATERIALS... 

From these observations, one may conclude that the diol product arises directly from an iron-based oxidant, rather than from a carbon-based radical intermediate that captures OH or other oxygen-based radicals as in the mechanism proposed for the pentadentate ligand based catalyst. The formation of epoxide, however, is proposed to occur in a similar pathway to that described above, although the Fe—O—C—C-type intermediate then must have a shorter lifetime. Based on this interpretation, which admittedly is not the only possible one, one would conclude that no OH are present, and this is in agreement with the DFT-based suggestion that there is a direct formation of the iron(IV) catalyst firom its iron(II) precursor and H2O2, a proposal that is in agreement with the fact that no iron(III) intermediates are observed (see Scheme 22, Fig. 22). 

In nature, oxidation reactions are essential for aerobic life. Energy for cells is provided by the combustion of carbohydrates and fatty acids with dioxygen. Oxidation reactions are also involved in biosynthesis, metabolism reactions, and the detoxification of harmful compounds. In several of these reactions, iron or manganese enzymes are involved. These manganese and iron enzymes have frequently been used as a source of inspiration for the development of manganese- and iron-based oxidation catalysts. 

FIGURE 8 The X-ray powder diffraction (XRD) patterns of two ferrocene-containing polyphenylene samples FP-6 (b), and FPSC-5 (c) after heating at 250°C, and the model spectra of two iron-based oxides (a). 

Breakaway corrosion (Fig. 4) commonly occurs if numerous cracks continuously form and extend rapidly through the scale. It can also occur for alloys that have had one component (principally the most stable scale former) either effectively depleted from the alloy through repeated scale formation and spallation or through selective internal compound formation. Breakaway corrosion leaves bare substrate continuously exposed. Mass change measurements are meaningless during breakaway corrosion as scales rapidly form and break away from the substrate. Efforts to predict the onset of breakaway corrosion have been attempted for iron-base oxide dispersion alloys [4],... 

The calcination of titanium-containing Prussian blue analog, KQ25Ti[Fe(jg75(CN) ]-bH O, led to microstructural nanoporous cubes of mixed titanium-iron-based oxides, Ti02-Fe203 that retained the precursor s cubic morphology [121]. 

Ekkati, A., Kodanko, J. Targeting peptides with an iron-based oxidant cleavage of the amino acid backbone and oxidation of side chains. J. Am. Chem. Soc. 129,... 

Although acrylonitrile manufacture from propylene and ammonia was first patented in 1949 (30), it was not until 1959, when Sohio developed a catalyst capable of producing acrylonitrile with high selectivity, that commercial manufacture from propylene became economically viable (1). Production improvements over the past 30 years have stemmed largely from development of several generations of increasingly more efficient catalysts. These catalysts are multicomponent mixed metal oxides mostly based on bismuth—molybdenum oxide. Other types of catalysts that have been used commercially are based on iron—antimony oxide, uranium—antimony oxide, and tellurium-molybdenum oxide. 

Iron(III) hydroxide [1309-33-7], FeH02, is a red-brown amorphous material that forms when a strong base is added to a solution of an iron(III) salt. It is also known as hydrated iron(III) oxide. The fully hydrated Fe(OH)3 has not been isolated. The density of the material varies between 3.4-3.9 g/cm, depending on its extent of hydration. It is insoluble in water and alcohol, but redissolves in acid. Iron(III) hydroxide loses water to form Fe203. Iron(III) hydroxide is used as an absorbent in chemical processes, as a pigment, and in abrasives. Salt-free iron(III) hydroxide can be obtained by hydrolysis of iron(III) alkoxides. 

Iron Oxide Yellows. From a chemical point of view, synthetic iron oxide yellows, also known as iron gelbs, are based on the iron(III) oxide—hydroxide, a-FeO(OH), known as goethite. Color varies from light yellows to dark buffs and is primarily determined by particle size, which is usually between 0.1 and 0.8 p.m. Because of their resistance to alkahes, these are used by the building industry to color cement. Thermally, iron oxide yellows are stable up to 177°C above this temperature they dehydrate to iron(III) oxide ... 

Iron Blocks. Chemically, iron blacks are based on the binary iron oxide, FeOFe2 O3. Although the majority is produced in the cubical form, these can also be produced in acicular form. Most of the black iron oxide pigments contain iron(III) oxide impurities, giving a higher ratio of iron(III) than would be expected from the theoretical formula. 

Until recently only few examples on asymmetric epoxidation using iron-based catalysts were reported in the literature (Scheme 6) [42-44]. With [Fe(BPMCN) (CF3S03)2] 10, 58% of the epoxide with 12% ee was obtained in the oxidation of frans-2-heptene [42]. 

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