Chlorides of metals

The reaction provides a valuable method of preparing anhydrous chlorides of metals. It has been used to prepare the anhydrous chlorides of copper(II), zinc, cadmium, chromium(III), iron(III). cobalt(Il) and nickel. 

The chlorination is mostly carried out in fluidized-bed reactors. Whereas the reaction is slightly exothermic, the heat generated during the reaction is not sufficient to maintain it. Thus, a small amount of oxygen is added to the mixture to react with the coke and to create the necessary amount of heat. To prevent any formation of HCl, all reactants entering the reactor must be completely dry. At the bottom of the chlorination furnace, chlorides of metal impurities present in the titanium source, such as magnesium, calcium, and zircon, accumulate. 

Metallic powders are made several different ways. They can be prepared by reducing salts in a stream of a reducing gas, such as hydrogen chlorides of metals are commonly used but oxides are used too. Thermal decomposition in a vacuum of metal carbonyls or metal salts of organic acids, such as formates, produces metal powders. Surface areas of such powders are around 1.5 m2/g. Powders can also be made from electrolytic reduction of salts in organic solvents and by atomization of the metal. 

Eichler, B., Domanov, V.P., Zvara, I. Evaluation of heat of adsorption from Thermochromatographie Data. II. Chlorides of Metals. The Adsorption on Quartz". In Joint Institute for Nuclear Research Report, Dubna, (1976) GSI-tr.-4/76. 

The chlorides of metals with an intermediate electronegativity tend to form chloride alkoxides, but these reactions can be brought to completion in the presence of proton acceptors such as NH3 or alkali metals (K/Na/Li). 

The fact that the elements become less metallic, from left to right across a period, is shown by the characters of their chlorides and oxides. The chlorides of metals on the left-hand side of a period are ionic and dissolve in water to form neutral solutions whereas the chlorides of non-metals on the right-hand side of the table are covalent and react with water. There is a gradual change between these two extremes across the period. Consider the chlorides of period 3 ... 

More than two decades after the preparation of a large nnmber of the so-caUed alkoxo salts by Meerwein and Bersin in 1929, U Al(OPr )4 4 was synthesized in 1952 by Albers et al. and evidence for the formation of M U(OEt)6 n (M = Na, Ca, Al) was obtained by Jones et al in 1956. Similarly, formation of a number of anionic methoxide species was indicated in the potentiometric titrations of chlorides of metals (B, Al, Ti, Nb, Ta) with lithium methoxide in methanol by Gut in 1964. Ludman and Waddington studied the conductometric titrations of a wide variety of Lewis acids with basic metal methoxides and reported the formation of alkoxo salts of the type KB(OMe)4 and K3Fe(OMe)e. Schloder and Protzer also synthesized a number of bimetallic alkoxides of aluminium with the formulae, MAl(OMe)4 and M Al(OMe)4 2 where M and M are alkali and alkaline earth metals respectively. 

Alkali chlorides and chlorides of metals, which are not reduced by Ti, do not interfere seriously, but the time of a blank reaction is, in general, decreased. Alkali sulfates and magnesium sulfate markedly increase the speed of reaction between malachite green and Ti in the absence of tungsten, and consequently decrease the catalyzing effect. Nitrates and fluorides must be absent. The former are reduced by fluorides form stable... 

A catalyst is essential for the economic oxidation of hydrogen chloride to chlorine by air or oxygen (Deacon Process), and the catalyst must be active at low temperature and have adequate life. There are many patents claiming improved catalysts and equipment. Most of the catalysts are oxides and/or chlorides of metals on various substrates. Only three processes have been commercialized. 

Razuvaev, G. a., M. S. Fedotov, T. N. Zaichenko, and N. A. Kyl-Vinskaya Reactions of tetraphenyl lead and tetraphenyl tin with chlorides of metals which fail to form stable organometalhc compounds. (In Russian). Sbomik Statei Obschei Khim. 2, 1514 (1953) through Chem. Abstr. 49, 5346 (1955). 

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