Gaseous metal chlorides

A compilation of optimum physical properties of CVD-derived Nb3Ge films (i.e., T, 7c, and //c2 values of 22.5 K, 1.8 x 10 Acm " and 27.3 T) is listed in Table 2-4. Evaluated variables for Nb3Ge film growth include substrate temperature, the gaseous metal chloride hydrogen mole ratio in the carrier gas stream, NbCU (g) to GeCb (g) mole ratio, and the reactor viscosity (Reynolds number). 

Figure 2-14. Computed CVD phase diagram for the A15 phase (i.e., NbaGe) with deposition temperature (Tj) and a gaseous metal-chloride ratio parameter (g) as independent variables. (From Weiss et al. [94].)...

In recent years the colors produced by fireworks have become more intense because of the formation of metal chlorides during the burning process. These gaseous metal chloride molecules produce colors much more brilliant than do the metal atoms by themselves. For example, strontium chloride produces a much brighter red than do strontium atoms. Thus, chlorine-donating compounds are now included in many fireworks shells. 

Schematic of the three situations that are used for the assessment of metal chloride evaporation, (a) Vapor pressure of the gaseous metal chloride above solid or liquid metal chloride in a closed system (value used in Equation 13.23 and for determining T ). (b) Equilibrium partial pressure of pMe Cl in a closed system containing O2 and CI2 as gas phase and Me, Me Oj, and Me,.Cly as solid or liquid phases (value used for the establishment of the "static" quasi-stability diagram), (c) Mej.Cly transport rate in the gas boundary layer (metal consumption rate) as criterion for the amount of chlorine-induced corrosion in an open system with gas flow across the surface (value used for the establishment of the "dynamic" quasi-stability diagram).

Physical properties of hexachloroethane are Hsted in Table 11. Hexachloroethane is thermally cracked in the gaseous phase at 400—500°C to give tetrachloroethylene, carbon tetrachloride, and chlorine (140). The thermal decomposition may occur by means of radical-chain mechanism involving -C,C1 -C1, or CCl radicals. The decomposition is inhibited by traces of nitric oxide. Powdered 2inc reacts violentiy with hexachloroethane in alcohoHc solutions to give the metal chloride and tetrachloroethylene aluminum gives a less violent reaction (141). Hexachloroethane is unreactive with aqueous alkali and acid at moderate temperatures. However, when heated with soHd caustic above 200°C or with alcohoHc alkaHs at 100°C, decomposition to oxaHc acid takes place. 

When hemin (1) is treated with gaseous hydrogen chloride in anhydrous methanol/pyridine in the presence of iron(II) sulfate, protoporphyrin dimethyl ester (2), the metal-free ligand of hemin. is produced in almost quantitative yield. This compound is quite sensitive to oxygen... 

In a reactor at low pressure (0.2-0.3 MPa) and moderate temperature (375 °C) the PVC is chemically and thermally degraded. A particular feature of the process is that the chlorine in the PVC reacts in part with the fillers in PVC and is neutralised with the formation of CaCl2. In similar vein, metal stabilisers in PVC are converted into the respective metal chlorides (lead, cadmium, zinc and/or barium). At current PVC waste compositions these chlorides consist of 60% lead which can be purified and re-used. The reaction in the end results in the following solid, liquid and gaseous products. 

When dehydrating a compound such as a metal chloride, the gaseous products of the reaction make it easy to separate the anhydrous solid compound. 

Cesium acetylide, 11 195 Cesium aluminum hydride, preparation and properties of, 8 323 Cesium carbide, 11 195 Cesium chloride, 2 5-6 gaseous metal halide complexes, 26 204-206... 

Gaseous Metal Treatment. In order to protect ordinary iron and steel items from rusting, they were coated, in Germany, by the diffusion of chromous chloride vapor at high temperature. The method was briefly described in Ref 1 and listed in Ref 2 Refs 1) BIOS Final Repts 839(1946) 1534(1946) 2) PATR 2510(1958), p... 

Caution. Due to the toxic nature of metal carbonyl and the lachrymatory properties of gaseous hydrogen chloride, this procedure must be carried out in a well-ventilated hood. 

Tricresylphosphate can also be obtained by the continuous technique. In this case etherification is carried out in a cascade of consequtive reactors operating at increasing temperatures the maximum temperature can reach 200 °C if the reaction is catalysed with metal halogenides. To reduce the losses of phosphorus chlorooxide with gaseous hydrogen chloride, the process should be carried out at reduced pressure. 

In this method metal chlorides or oxychlorides are made to react with gaseous hydrocarbons in the vicinity of a localized heat source (1400-2100 K). Clearly, the reaction is thermodynamically favorable (Tables 3 and 4). The method was first used by Van Arkel in 1923 with an incandescent tungsten filament to make carbides of tantalum and zirconium [40]. Although the reaction variables have been studied extensively, problems remain with control of the process and with low productivity. Application to catalyst synthesis has been moderate [41],... 

An alternate process for winning copper from cupriferous iron ore was segregation roasting, in which the hot ore was mixed with small amounts of common salt and powdered coal, in order to transport the copper content of the ore via gaseous copper chlorides to the coal particles, where they were reduced in situ to the metal. The copper-coated char could be concentrated by... 

Three routes pursued to achieve this conversion are catalytic oxidation of gaseous HQ, direct oxidation of HQ by an inorganic oxidizing agent, and two-stage processes involving intermediate formation of a metal chloride from either its oxide or oxychloride and subsequent release of the clilorine by air, oxygen, or heat. Only two of these processes have been commercialized. 

I, II, (>II ) noble metal, very volatile or gaseous oxides, chlorides and bromides unstable due to relativistic effect on 7s electrons, MF2 stable, stable complexes MX4 (X = 1, Br, Cl) in aqueous solutions, many complexes properties of M+ between those of Tl" and Ag" ", MCI... 

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