Tellurium Monoxide, TeO

Tellurium Monoxide or Tellurium Suboxide, TeO, is produced when tellurium-sulphur sesquioxide is heated in a vacuum at 180° to 225° C., the residue being washed with sodium carbonate solution, hot water and finally alcohol:

TeSO₃ = TeO + SO₂.

According to Damiens, however, the substance obtained is a mixture of tellurium and tellurium dioxide.

In dry air tellurium monoxide is a stable, amorphous, grey powder, or a porous solid, to which a graphitic lustre can be imparted by pressure. It is slowly oxidised in moist air and also when heated in dry air, being converted into the dioxide.

Oxidising agents such as nitric acid and potassium permanganate convert the monoxide into the dioxide. Concentrated sulphuric acid has a somewhat similar effect, the red solution primarily produced slowly depositing tellurium sulphate:

2TeO + 3H₂SO₄ = Te(SO₄)₂ + TeSO₃ + 3H₂O.

Compared with tellurium and tellurium dioxide, tellurium monoxide is relatively unstable, as can be shown by the ease with which it passes into these two substances, for example when heated strongly in a vacuum or when treated with dilute acids or alkalis:

2TeO = Te + TeO₂.

The monoxide absorbs gaseous hydrogen chloride without any marked change in appearance, but on heating some tellurium dichloride sublimes; the direct relationship between these two compounds is thus demonstrated.