Elemental germanium preparation

The action of alkyl halides on elemental germanium in the presence of a copper/gallium catalyst leads to the simultaneous preparation of several or all of the above-mentioned organogermanium halides248 ... 

Reaction (1) is similar to that used for the preparation of other volatile chlorides (BC13, TiCl4) reaction (2) has already been mentioned in connection with the recovery of germanium. Preparations of SnBr4 and Snl4 from the elements are also convenient. 

Elemental germanium is used primarily in the preparation of semiconductors in which it is combined with phosphorus, arsenic, or antimony to make n-type semiconductors or with gallium to make p-type semiconductors. 

Ge(C2H5)4 deserves some prominence as it was prepared only one year after the discovery of elemental germanium by Clemens Winkler at the Bergakademie Freiberg in Germany [30]. 

The action of methyl chloride upon elemental germanium in the presence of a copper catalyst yields a mixture of related organogermanium chlorides, from which the individual substances can be separated by distillation. The composition of the mixture is influenced by the temperature of the reacting mass, the type of catalyst used, the manner in which the catalyst is associated with the germanium, and the possible time of contact. The method is best suited to the preparation of the lower dialkyldihalogermanes. Compounds of the type R3GeCl and R4Ge are present as only a small fraction of the total yield. 

In humans, germanium is widely distributed throughout the body. Hamilton et al. [28] found the highest germanium concentrations in kidney (5 p,g/g fresh tissue) and lower ones in brain (0.1 xg/g fresh tissue). In users of germanium preparations, particularly high accumulations of this element were found in spleen, renal cortex, brain, and skeletal muscle [29], as well as in hair and nails [30]. 

Although direct combination of the elements is feasible, germanium dihalides are usually prepared by... 

Salt elimination reactions proved to be very effective for the synthesis of closo-heteroborates with the heavy elements of this group. Todd and co-workers prepared for the first time the lead, tin and germanium cluster dianions [EBnHn]2 as shown in Scheme 3.3-5 [17]. 

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