Germanium tetrabromide

These redistribution reactions are possible at atmospheric pressure under the action of MW irradiation is performed for a few minutes in the presence of the same catalysts [57]. These reactions with the less volatile germanium tetrabromide (44b) (b.p. 184 °C) have also been performed by use of the GS/MW process, without added catalyst (Tab. 7.4, entries 1 and 3) [15, 16]. In this instance, despite the use of weaker incident power, the temperature reached 420 °C, very much higher than that obtained under the action of MW irradiation of a reaction mixture containing AlBr3 (200 °C to 250 °C) (Tab. 7.4, entries 2 and 4). The presence of this catalyst considerably favors redistribution towards the dibrominated products (46b) (84% for R = nBu, 85% for R = Ph) relative to the monobrominated compounds (46a), which are the major products of the GS/MW process (78% and 43% respectively). The tri-brominated products (46c), the most difficult to prepare, have been obtained with a rather high selectivity (73 to 80%) by use of the catalytic process under the action of MW [57]. In this reaction, therefore, the GS/MW process seems less effective than the MW-assisted and AlX3-catalyzed process. 

Tab. 7.4 Redistribution reactions between germanium tetrabromide (44b) and tetrabutyl- or tetra-phenylgermanes (45) under the action of MW irradiation [15, 16].

Germanium refinery flow diagram, 12 556 Germanium tetrabromide, 12 552 Germanium tetrachloride, 12 551-552,... 

Wa.ns and Richards have measured the heats of formation of germanium tetrabromide and tetraiodide by measuring the heats of solution of these compounds, and that of germanium dioxide, in aqueous caustic soda. They deduced L (Ge-Br) and (Ge-I) to be 63 5 and 48 1 kcal respectively, using the N.B.S.329 value for the heat of atomization of germanium. After correction to the value for the heat of atomization of germanium adopted here, they become 66 and 51 kcal respectively. 

FeS2 IRON DISULFIDE 720 GeBr4[g] GERMANIUM TETRABROMIDE (GAS) 762... 

In one instance, however, application of the synthetic method led to unexpected results. An excess of isopropylmagnesium bromide reacted with germanium tetrabromide to produce an isopropylgermanium polymer of unknown structure along with other products, but no hexaisopropyl-... 

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