Zirconium Nitrates

The salt Zr(NO₃)₄.5H₂O, first described by Paykull, was obtained by Rosenheim and Frank in hygroscopic prisms by evaporating a nitric acid solution of zirconium hydroxide over phosphoric oxide and sodium hydroxide. Mandl obtained a basic nitrate soluble in water; and Muller, in a study of colloidal zirconium hydroxide, formed the opinion that zirconium nitrate and other zirconium salts are not of constant composition, because a solution containing the nitrate loses nitric acid on evaporation, and the product, which dissolves in water, yields a slightly opalescent solution containing colloidal zirconia. The question here arises whether, in analogy with the sulphate, zirconium nitrate, Zr(NO₃)₄.5H₂O, should be written as zirconyl-nitric acid, ZrO(NO₃)₄H₂.4H₂O, but the question cannot be certainly answered. On evaporating a solution of the nitrate at 75° C. the basic nitrate ZrO(NO₃)₂.2H₂O separates as a white powder, and on mixing the alcoholic solution of this salt with ether the more basic nitrate Zr₂O₃(NO₃)₂.5H₂O is formed.