Physical Properties
Colorless liquid; density 1.879 g/cm3 at 20°C and 1.844 g/cm3 at 30°C; refractive index 1.464; solidifies at –49.5°C; decomposes in water; soluble in alcohol, ether, benzene, chloroform and carbon tetrachloride; insoluble in concentrated hydrochloric and sulfuric acids.
Preparation
Germanium(IV) chloride is prepared by reacting germanium metal with chlorine; or by treating germanium oxide, GeO2, with hydrochloric acid:
Ge + 2Cl2 → GeCl4
GeO2 + 4HCl → GeCl4 + 2H2O
Germanium(IV) chloride often is obtained as a byproduct of germanium metal production. The process involves heating germanium oxide, GeO2, with sodium chloride and coal. The vapors of germanium(IV) chloride and other volatile chlorides formed from the impurity metals are condensed. The product is isolated by fractional distillation. Further purification may be achieved by fractional distillation in 8N HCl and chlorine, or in the presence of other oxidizing agents in quartz stills.
Germanium(IV) chloride also is obtained by chlorination of germanium(II) chloride at ambient temperature. The reaction is rapid.
GeCl2 + Cl2 → GeCl4
Reactions
Germanium(IV) chloride reacts with water, hydrolyzing to germanium oxide and hydrochloric acid:
GeCl4 + 2H2O → GeO2 + 4HCl
The rate of hydrolysis is slower than the corresponding silicon analog, with hydrolysis occurring only partially. When heated with hydrogen at 1,000°C in a quartz reactor, it is converted into germanium(I) chloride, condensing onto the wall of the reactor:
2GeCl4 + 3H2→ 2GeCl + 6HCl
When vapors of GeCl4 are passed over germanium at elevated temperatures, the product is germanium(II) chloride, GeCl2:
GeCl4 + Ge→ 2GeCl2
Reaction with lithium aluminum hydride in ether forms monogermane, GeH4:
GeCl4 + LiAlH4 →GeH4 + LiCl + AlCl3
Reactions with antimony trifluoride, SbF3 in the presence of antimony pentachloride, SbCl5, form mixed halides of compositions: GeCl3F, GeCl3F2, GeCl2F2, and GeClF3.
Reactions with alcohols in the presence of an amine yield alkoxides:
GeCl4 + 4CH3OH + 4C2H5NH2 → Ge(OCH3)4 + 4C2H5N•HCl
Germanium forms six coordinate adducts, such as GeCl4(L)2 with many neutral ligands.
Chemical Properties
Colorless liquid. decomposes in water. Insoluble in concentrated
hydrochloric acid; soluble in carbon disulfide, chloroform,
benzene, alcohol, and ether.
Physical properties
Colorless liquid; density 1.879 g/cm
3 at 20°C and 1.844 g/cm
3 at 30°C; refractive index 1.464; boils at 86.5°C; solidifies at -49.5°C; decomposes in water; soluble in alcohol, ether, benzene, chloroform and carbon tetrachloride; insoluble in concentrated hydrochloric and sulfuric acids.
Uses
It is used as a catalyst in the conversion of carbohydrates into 5-hydroxymethylfurfural in ionic liquids, as a reducing agent in combination with triphenylphosphine (TPP) for the reduction of alpha-bromo carboxylic acid derivatives, and in the production of pure germanium. It also finds use as an intermediate for several optical processes. It is one of the most important dopants in silica glass for optical fibers. It is employed in the preparation of germanium dioxide which is used for wide camera lens, microscopy, IR-transparent glasses/windows/lenses, and for the core of fiber-optic lines.
Uses
Germanium(IV) chloride is used in the microwave preparation of Ge2Cl6, a colorless crystalline material which was included in a further study of low-valent germanium compounds.1
Germanium(IV) chloride is used in the preparation of many germanium compounds.
Flammability and Explosibility
Non flammable
Safety Profile
Poison by intravenous
route. Mddly toxic by inhalation. A skin,
severe eye, and mucous membrane irritant.
Will react violently with water or steam to
produce toxic and corrosive fumes. When
heated to decomposition it emits toxic
fumes of Cl-. See also GERMANIUM
COMPOUNDS.
Purification Methods
Traces of Cl2 and HCl can be removed from the liquid by blowing dry air through it for a few hours at room temperature or by shaking it with Hg or Hg2Cl2 and then fractionating it in a vacuum. It decomposes on heating at 950o. It has a sharp penetrating odour and fumes in moist air to give a chalky coat of GeO2. It is slowly hydrolysed by H2O to give GeO2, but distils from conc HCl. [Foster et al. Inorg Synth II 109 1946, Dennis & Hance J Am Chem Soc 44 304 1922, Schenk in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 715 1963.] LACHRYMATORY. Glass powder (100-300 mesh). Washed with 10% HNO3, water and dry in air.
