_chloride.gif)
Zirconium(IV) chloride
Encyclopedia
Zirconium chloride, also known as zirconium tetrachloride, is an inorganic compound
frequently used as a precursor to other compounds of zirconium. This white high-melting solid hydrolyzes rapidly in humid air.
, solid ZrCl4 adopts a polymeric structure wherein each Zr is octahedrally coordinated. This difference in structures is responsible for the striking difference in their properties: is distillable, but is a solid with a high melting point. In the solid state, ZrCl4 adopts a tape-like linear polymeric structure—the same structure adopted by HfCl4
. This polymer degrades readily upon treatment with Lewis bases, which cleave the Zr-Cl-Zr linkages.
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. This conversion entails treatment of the oxide with carbon as the oxide "getter" and chlorine.
. This reaction is rapid and virtually irreversible, consistent with the high oxophilicity
of zirconium(IV). For this reason, manipulations of ZrCl4 typically require air-free technique
s.
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.
ZrCl4 can be reduced with Zr metal to produce zirconium(III) chloride
.
for the Friedel-Crafts reaction
, the Diels-Alder reaction
and intramolecular cyclisation reactions. It is also used to make water-repellent treatment of textile
s and other fibrous materials.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
frequently used as a precursor to other compounds of zirconium. This white high-melting solid hydrolyzes rapidly in humid air.
Structure
Unlike molecular TiCl4Titanium tetrachloride
Titanium tetrachloride is the inorganic compound with the formula TiCl4. It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. TiCl4 is an unusual example of a metal halide that is highly volatile...
, solid ZrCl4 adopts a polymeric structure wherein each Zr is octahedrally coordinated. This difference in structures is responsible for the striking difference in their properties: is distillable, but is a solid with a high melting point. In the solid state, ZrCl4 adopts a tape-like linear polymeric structure—the same structure adopted by HfCl4
Hafnium(IV) chloride
Hafnium chloride is the inorganic compound with the formula HfCl4. This colourless solid is the precursor to most hafnium organometallic compounds. It functions as a Lewis acid and catalyst for certain alkylation and isomerism reactions...
. This polymer degrades readily upon treatment with Lewis bases, which cleave the Zr-Cl-Zr linkages.
Kroll process
ZrCl4 is an intermediate in the conversion of zirconium minerals to metallic zirconiumZirconium
Zirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
by the Kroll process
Kroll process
Kroll Process is a pyrometallurgical industrial process used to produce metallic titanium. It was invented by William J. Kroll in Luxembourg. After moving to the United States, Kroll further developed the method for the production of zirconium...
. 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. This conversion entails treatment of the oxide with carbon as the oxide "getter" and chlorine.
- ZrO2 + 2 C + 2 Cl2 → ZrCl4 + 2 CO
Chemical reactions
Hydrolysis of ZrCl4 gives the hydrated hydroxy chloride cluster called zirconyl chlorideZirconyl chloride
Zirconyl chloride is the inorganic compound with the formula [Zr41216]Cl812. Zirconyl chloride is a misnomer because the compound contains no oxide groups, but the term is widely used. This salt, a white solid, is the most common water-soluble derivative of zirconium.-Production and structure:The...
. This reaction is rapid and virtually irreversible, consistent with the high oxophilicity
Oxophilicity
Oxophilicity is the tendency of certain chemical compounds to form oxides by hydrolysis or abstraction of oxygen, often from organic compounds. The term is usually used to describe metal centers, commonly the early transition metals such as titanium, niobium, and tungsten. Oxophilic metals are...
of zirconium(IV). For this reason, manipulations of ZrCl4 typically require air-free technique
Air-free technique
Air-free techniques refer to a range of manipulations in the chemistry laboratory for the handling of compounds that are air-sensitive. These techniques prevent the compounds from reacting with components of air, usually water and oxygen; less commonly carbon dioxide and nitrogen...
s.
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
Tetrahydrofuran
Tetrahydrofuran is a colorless, water-miscible organic liquid with low viscosity at standard temperature and pressure. This heterocyclic compound has the chemical formula 4O. As one of the most polar ethers with a wide liquid range, it is a useful solvent. Its main use, however, is as a precursor...
: CAS [21959-01-3], mp 175-177 °C. NaC5H5 reacts with ZrCl4(THF)2 to give zirconocene dichloride
Zirconocene dichloride
Zirconocene dichloride is an organozirconium compound composed of a zirconium central atom, with two cyclopentadienyl and two chloro ligands. It is a colourless diamagnetic solid that is somewhat stable in air.-Preparation:...
, 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
Durene
Durene, or 1,2,4,5-tetramethylbenzene, is an aromatic hydrocarbon used as a solvent. It is also an intermediate in the manufacture of pyromellitic acid, which is used for manufacturing curing agents, adhesives and coating materials...
. This solubilization arises through the formation of π-complexes.
ZrCl4 can be reduced with Zr metal to produce zirconium(III) chloride
Zirconium(III) chloride
Zirconium chloride is a the inorganic compound with formula ZrCl3. It is a blue-black solid that is highly sensitive to air.-Preparation:...
.
Uses
In organic synthesis zirconium tetrachloride is used as a weak Lewis acidLewis acid
]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...
for the Friedel-Crafts reaction
Friedel-Crafts reaction
The Friedel–Crafts reactions are a set of reactions developed by Charles Friedel and James Crafts in 1877. There are two main types of Friedel–Crafts reactions: alkylation reactions and acylation reactions. This reaction type is a form of electrophilic aromatic substitution...
, the Diels-Alder reaction
Diels-Alder reaction
The Diels–Alder reaction is an organic chemical reaction between a conjugated diene and a substituted alkene, commonly termed the dienophile, to form a substituted cyclohexene system. The reaction can proceed even if some of the atoms in the newly formed ring are not carbon...
and intramolecular cyclisation reactions. It is also used to make water-repellent treatment of textile
Textile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
s and other fibrous materials.