Position for rhenium combustion entire heating operation should last no more than 2 to 3 hours. The red product is pure Re08. Yield, quantitative.Position for carbon monoxide reduction v Properties Rhenium(V1) oxide is a red solid, crystallizing in the cubic system. In thin layers, the oxide appears green by transmitted light. It is unreactive to water and to most reagents of nonoxidizing or reducing character. At 400°, it disproportionates in a vacuum to rhenium(1V) and rhenium(VI1) oxides.Rhenium(VI1) oxide can be prepared from the metal or from lower rhenium oxides by direct oxidation in a stream of air or oxygen.'O2 When this is done, however, a variable