Pertitanates

It was observed by Schone that the addition of hydrogen peroxide to a titanic solution produces a yellow colour. There are thus produced compounds of titanium superoxide, TiO₃. This oxide is best produced, in a hydrated form, by slowly adding titanic chloride to dilute alcohol, followed by a large excess of hydrogen peroxide and then ammonia or other alkali. A reddish yellow liquid is thus produced from which a yellow precipitate gradually separates, which when dried corresponds approximately to the formula TiO₃.3H₂O. The question whether this compound may be really TiO₂.H₂O₂.2H₂O is to be answered in the negative by reason of the fact that its solution does not show the reaction with chromic acid characteristic of hydrogen peroxide, and also because of the existence of the fluoroxypertitanates (q.v.) which are anhydrous derivatives of TiO₃. The constitution of TiO₃.3H₂O is therefore


or possibly


the titanium being in neither case more than quadrivalent.

Melikoff and Pissarjewski have prepared a number of salts of pertitanic acid with metallic superoxides by adding well-cooled hydrogen peroxide to TiO₃.aq. followed by sufficient alkali to make a clear solution. The salts are then precipitated by alcohol. The following compounds have thus been obtained:

Na₂O₂.TiO₃.3H₂O, (NH₄)₂O₂.TiO₃.H₂O₂, BaO₂.TiO₃.5H₂O, K₂O₂.TiO₃.10H₂O, (Na₂O₂)₄.Ti₂O₇.10H₂O.

The constitution of the first two salts is represented thus:

and

For the last and similar salts Melikoff and Pissarjewski assume the titanium to be more than quadrivalent, formulating (Na₂O₂)₄.Ti₂O₇.10H₂O as



The fluoroxypertitanates, to which reference has been made above, are formed when alkali or alkaline earth fluoride is added to a titanic acid solution containing hydrogen peroxide. The following are examples of these crystalline salts:

TiO₂F₂.3NH₄F, TiO₂F₂.2KF, TiO₂F₂.BaF₂.

They are derivatives of pertitanic acid, in which an atom of oxygen has been replaced by two of fluorine; and are decomposed by hydrofluoric acid thus:

TiO₂F₂ + 2HF = TiF₄ + H₂O₂.

The constitution of TiO₂F₂.2KF may be thus represented:



Mazzucchelli and Pantanelli have prepared the following inorganic salts of titanium peroxide:

TiO₂(KSO₄)₂.7H₂O, TiO₂(NaSO₄)₂.10H₂O, TiO₂(NH₄SO₄)₂.xH₂O, TiO₂(LiSO₄)₂.7H₂O, TiO₂Cl₂.2NaCl.9H₂O, TiO₃.P₂O₅.Na₂O.3H₂O. O(TiO₂.P₂O₅.Na₂O)₂.24H₂O.