Anhydrous Metal Halides

Inorganic Chlorides/Halides — These metallic salts are formed from the reaction of a weak base with the strong acid HCl. Salts such as these dissolve in water to produce a markedly acidic solution. This is exemplified by aluminum chloride, which is corrosive due to the acidity resulting from the hydrolysis that produces aluminum and chlorine ions. Anhydrous AICI3 hydrolyzes violently when contacted by water. 

Such reactions provide an excellent route to anhydrous metal nitrates, particularly when metal bromides or iodides are used, since then the nitrosyl halide decomposes and this prevents the possible... 

A final group of reactions are those involving water. A wide variety of materials such as the alkali metals light metals and their hydrides strong acids, such as sulphuric acid anhydrous metal oxides anhydrous metal halides and non-metal oxides ail react vigorously or violently with water under various circumstances. 

A number of substances react vigorously with water, sometimes with the formation of hydrogen gas, which itself may ignite in the presence of air. Examples or such reactants are alkali metals, finely divided light metals and their hydrides, anhydrous metal oxides, anhydrous metal halides, nonmetal halides, and nonmetal oxides as well as certain organics such as anhydrides... 

Anhydrous metal halides Aluminum tribromide, germanium tetrachloride, titanium tetrachloride... 

Sulfurous oxychloride is used as a chlorinating agent for making sulfoxides and acyl chlorides. It also is used in pesticide formulations and to prepare anhydrous metal halides from their hydrated halides or hydroxides. 

Protic acids are usually used as catalysts for alkylation with olefins rather than with alkyl halides. Anhydrous hydrogen chloride, in the absence of metal halides, is a catalyst for the alkylation of benzene with terf-butyl chloride only at elevated temperatures96 where an equilibrium with isobutylene may exist. Other alkyl halides and cyclohexene were also reacted with benzene and toluene using this catalyst. 

BC13, BBr3, and BI3 undeigo exchange reactions to yield mixed boron halides. Exchange reactions also occur with trialkyl, triaryl, trialkoxy, or triaryloxy boranes and with diborane. Anhydrous metal bromides and iodides can be prepared by the exchange reaction of the metal chloride or oxide and BBr3 or BI3 (21). 

Anhydrous metal halides may be formed by direct reaction ... 

Reaction XX. (6) Action of certain Anhydrous Metallic Halides (Aluminium Chloride, Aluminium Bromide, Aluminium and Hydrogen Chloride, Ferric Chloride) on a mixture of an Aromatic Hydrocarbon or certain Derivatives, and an Acyl Halide. (Friedel-Crafts.) (A. Ch., [6], 1, 518.)—This is an even more important application of the Friedel-Crafts synthesis than the methods of synthesising hydrocarbons (pp. 58, 60). The reactions involved are more readily controlled since the products, in presence of aluminium chloride, do not undergo further condensations. Usually these products have also the advantage of being more easily separated, for, as shown below in (iii.), the formation of isomers can be avoided. 

See Inobganic Syntheses, 4,104 (1953) for the preparation of anhydrous metal halides. Sufficiently anhydrous calcium chloride for this synthesis may be prepared by heating the commercial anhydrous calcium chloride from a fresh, unopened bottle for about 2 hours at 400 to 500° in a stream of dry argon. 

Vanadium oxytrichloride is a lemon-yellow liquid with a boiling point of 127°1,2 and a freezing point of — 79.5°.2 Vapor-pressure data are also given in reference 2. Its chemical properties are those to be expected of a covalent, anhydrous metallic halide. It is very readily hydrolyzed and should be protected from moisture at all times. If the liquid has been exposed even briefly to moisture, its color will be orange or red, and it will contain an orange-red precipitate. 

Classification of Anhydrous Metal Halides. The metal halides vary in their properties from the ionic, high-melting, conducting compounds, such as sodium chloride, to the covalent, volatile, nonconducting compounds, such as osmium oetafluoride (m.p., 35°). The variations observed admit of some systematization by classification based on the oxidation state of the metal in the compound. 

Preparation of Anhydrous Metal Halides. The methods used to prepare high-purity samples of anhydrous metal... 

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