Iron chlorides silica support

Ethylamines. Mono-, di-, and triethyl amines, produced by catalytic reaction of ethanol with ammonia (330), are a significant oudet for ethanol. The vapor-phase continuous process takes place at 1.38 MPa (13.6 atm) and 150—220°C over a nickel catalyst supported on alumina, silica, or silica—alumina.. In this reductive amination under a hydrogen atmosphere, the ratio of the mono-, di-, and triethyl amine product can be controlled by recycling the unwanted products. Other catalysts used include phosphoric acid and derivatives, copper and iron chlorides, sulfates, and oxides in the presence of acids or alkaline salts (331). Piperidine can be ethylated with ethanol in the presence of Raney nickel catalyst at 200°C and 10.3 MPa (102 atm), to give IV-ethylpiperidine [766-09-6] (332). 

TPR and TPO patterns of silica-supported rhodium, iron, and iron-rhodium catalysts are shown in Fig. 11.5 [14]. These catalysts were prepared by pore volume impregnation from aqueous solutions of iron nitrate and rhodium chloride. Note the difference in reduction temperature between the noble metal rhodium and the non-noble metal iron. The bimetallic combination reduces largely in the same temperature range as the rhodium catalyst does, indicating that rhodium catalyzes the reduction of the iron. This forms evidence that rhodium and iron are well mixed in the fresh catalyst. The TPR patterns of the freshly prepared catalysts consist of two peaks, one coincides with that of the TPR pattern of the fully oxidized catalyst (right panel of Fig. 11.5) and can thus be... 

To establish the interaetion of the impregnating solutions with the surface of silica supports, Terorde measured the amount of water required to completely remove different iron salts applied onto the surface of silicagel in a column chromatograph [41], It appeared that an elution volume of water of 5.0 ml was required to remove the iron ammonium citrate, and of 6.2 ml to remove the Mohr s salt. Iron(III) chloride called for an elution volume of 6.3 ml, and iron(III) nitrate for a volume of 7.7 ml. Apparently, the iron species in the initially impregnated solution of iron ammonim citrate does not interact strongly with the silica surface. The relatively small interaction of the iron(III) complex of citric acid with the surface of silica indicates that the presence of the citric acid affects the adsorbed layer of water molecules that remains within the partially dried impregnated support. A thicker, less mobile layer of water molecules, citric acid anions, and iron(III) ions remains than without citric acid, where a layer of about six fairly mobile water molecules is present. 

Mao, J., Hu, X., Li, H., et al. (2008). Iron Chloride Supported on Pyridine-modified Mesoporous Silica An Efficient and Reusable Catalyst for the Allylic Oxidation of Olefins with Molecular Oxygen, Green Chem., 10, pp. 827-831. 

Wang L, Li J, Zhao X, Lv Y, Zhang H, Gao S. An efficient and scalable room temperature aerobic alcohol oxidation catalyzed by iron chloride hexahydrate/mesoporous silica supported TEMPO. Tetrahedron. 2013 69 6041-6045. 

The EDX spectrum (Fig. 11.8) shows the main surface scale impurity peaks of silica, aluminium, sodium, chloride and iron. If this EDX is compared to that of a new, clean membrane surface (Fig. 11.9), the clean surface shows sulphur, carbon and oxygen, which is typical of a porous polysulphone support. It was concluded that the scale is amorphous, composed of aluminosilicate and silicate. These compounds are normally found in trace amounts in brine solutions. Analysis showed that the surface could be cleaned with hydrochloric acid and analysis of the dissolved scale was similar to the EDX spectrum analysis. Review of the plant operation determined that the precipitation was the result of high pH in combination with high silica concentrations in the brine. 

Similar effects were observed by Stigter e< al. (185) with silica and aluminum chloride. The assumption of hydrolytic adsorption is supported by an observed increase of conductivity upon addition of silica to aluminum chloride solutions. Kautsky and Wesslau (240) observed hydrolytic adsorption of Th + ions. The reaction scheme given above is a simplification since, in reality, solutions of basic iron or aluminum salts contain polynuclear complexes. The size of the aggregates depends on pH and concentration. Chromatographic separation of various metal ions on silica gel columns was first described by Schwab and Jockers (241). The role of hydrolytic adsorption in column chromatography on silica gel was stressed by Umland and Kirchner (242). The use of this technique in analytical separations was investigated in detail by Kohlschiitter and collaborators (243-246). An application to thin-layer chromatography was described by Seiler (247). 

Catalysts (coni.) copper, for reaction of methyl chloride with silicon, 3 56 iron, for preparation of sodium amide, 2 133 nickel powder, 5 197 silica gel for, or for supports,... 

The use of a synthetic model system has provided valuable mechanistic insights into the molecular catalytic mechanism of P-450. Groves et al. [34]. were the first to report cytochrome P-450-type activity in a model system comprising iron meso-tetraphenylporphyrin chloride [(TPP)FeCl] and iodosylbenzene (PhIO) as an oxidant which can oxidize the Fe porphyrin directly to [(TPP)Fe =0] + in a shunt pathway. Thus, (TPP)FeCl and other metalloporphyrins can catalyze the monooxygenation of a variety of substrates by PhIO [35-40], hypochlorite salts [41, 42], p-cyano-A, A -dimethylanihne A -oxide [43-46], percarboxylic acids [47-50] and hydroperoxides [51, 52]. Catalytic activity was, however, rapidly reduced because of the destruction of the metalloporphyrin during the catalytic cycle [34-52]. When (TPP)FeCl was immobilized on the surface of silica or silica-alumina, catalytic reactivity and catalytic lifetime both increased significantly [53]. There have been several reports of supported catalysts based on such metalloporphyrins adsorbed or covalently bound to polymers [54-56]. Catalyst lifetime was also significantly improved by use of iron porphyrins such as mew-tetramesitylporphyrin chloride [(TMP)FeCl] and iron mcA o-tetrakis(2,3,4,5,6-pentafluorophenyl)por-phyrin chloride [(TPFPP)FeCl], which resist oxidative destruction, because of steric and electronic effects and thereby act as efficient catalysts of P-450 type reactions [57-65]. 

The intermolecular examples of synthetic value are self-couplings, e.g. formation of the dimer (43) from benzylsesamol, in 85% yield using vanadium oxytrifluoride preparation of the biaryl (44 95%), from 4-methylveratrole, employing iron(III) chloride supported on silica and synthesis of 4,4 -dimeth-oxybiphenyl (69%) fr om anisole by oxidation with thallium(III) trifluoroacetate in the presence of catalytic palladium(II) acetate. This approach has been used in a natural product synthesis. The dimers (45) and (46) were prepared from appropriate derivatives of gallic acid, and transformed into schizandrin C (47) and an isomer respectively. ... 

The process of ethane oxidative chlorination imposes heavy demands on the catalysts. The conventional salt supported catalysts are composed of Cu, K, Ca, Mn, Co, Fe, Mg, and other metal chlorides containing various additives these salts are precipitated on alumina, zeolites, silica gel, and other supports. Catalytic systems that represent solid solutions of iron cations in the lattice of the a-A Oa and a-Ct203 phases doped with cations, such as K, Ba, Ce, and Ag are also known [7]. 

Like cerium(IV), iron(III) salts can oxidize electron-rich centers by single-electron transfer to form radicals [1]. Early applications were developed for the oxidation of aromatic compounds, which undergo C-C bond formation to dimeric products. Because of their electronic properties, methoxy substituted arenes 25 are most reactive. Iron(III) chloride supported on silica gel was the reagent of choice, since inter-and intramolecular coupling products 26 are obtained in excellent yields (Scheme 8)... 

Diphenyl thioether and (meso-tetraphenylporphyrinato)iron(lll) chloride supported on silica, by treatment with 1 mole of iodosobenzene at ambient temperature, gave with stirring during 3 hours under nitrogen, diphenylsulphoxide in 74% yield with 7% of the corresponding sulphone, formation of which was suppresed by adsorption of the main product on the silica (ref. 123). 

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