Applications and reactions of Zirconium(IV) chloride

Zirconium(IV) chloride is used as a source of pure zirconium, as a tanning agent, in analytical chemistry and in treating textiles. Zirconium tetrachloride is decomposed by water. Corrosive to metals in the presence of moisture and to tissue.

Synthesis

This conversion entails treatment of the oxide with carbon as the oxide "getter" and chlorine.

ZrO2 + 2 C + 2 Cl2 → ZrCl4 + 2 CO

A laboratory scale process uses carbon tetrachloride in place of carbon and chlorine:

ZrO2 + 2 CCl4 → ZrCl4 + 2 COCl2

Applications

Precursor to Zr metal

ZrCl4 is an intermediate in the conversion of zirconium minerals to metallic zirconium by the Kroll process. In nature, zirconium minerals invariably exist as oxides (reflected also by the tendency of all zirconium chlorides to hydrolyze). For their conversion to bulk metal, these refractory oxides are first converted to the tetrachloride, which can be distilled at high temperatures. The purified ZrCl4 can be reduced with Zr metal to produce zirconium(III) chloride.

Other uses

ZrCl4 is the most common precursor for chemical vapor deposition of zirconium dioxide and zirconium diboride.

In organic synthesis zirconium tetrachloride is used as a weak Lewis acid for the Friedel-Crafts reaction, the Diels-Alder reaction and intramolecular cyclisation reactions.It is also used to make water-repellent treatment of textiles and other fibrous materials.

Reactions

ZrCl4 is the principal starting compound for the synthesis of many organometallic complexes of zirconium.Because of its polymeric structure, ZrCl4 is usually converted to a molecular complex before use. It forms a 1:2 complex with tetrahydrofuran: CAS [21959-01-3], mp 175–177 °C.NaC5H5 reacts with ZrCl4(THF)2 to give zirconocene dichloride, ZrCl2(C5H5)2, a versatile organozirconium complex.One of the most curious properties of ZrCl4 is its high solubility in the presence of methylated benzenes, such as durene. This solubilization arises through the formation of π-complexes.

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