Complex Sulphates of Tervalent Titanium

The above compound of titanium sesquisulphate and sulphuric acid may be alternatively described as titanosulphuric acid; the alkali salts of this acid will then be complex rather than double salts. By combination with rubidium and ammonium sulphates the following titanosulphates have been obtained by Stahler: 3Ti₂(SO₄)₃.Rb₂SO₄.24H₂O; 3Ti₂(SO₄)₃.(NH₄)₂SO₄.18H₂O. In addition to these a sodium salt of the composition Ti₂(SO₄)₃.Na₂SO₄.5H₂O has been obtained in violet crystals by the electrolytic reduction of sodium titanic sulphate solution. It is prepared technically and used as a reducing agent. Perchlorates can be reduced and estimated by its means.

Besides these salts titanium sesquisulphate forms alums, which, like other alums, diminish in solubility with increase in electropositiveness of the alkali metal. The rubidium and caesium salts, Rb₂SO₄.Ti₂(SO₄)₃.24H₂O and Cs₂SO₄.Ti₂(SO₄)₃.24H₂O have been prepared by Piccini.