Thorium Tartrate

If a solution of tartaric acid is added to a thorium salt solution a precipitate is formed which dissolves in excess of the acid. On diluting this solution a tartrate is reprecipitated which, according to Cleve, has the composition Th₃(OH)₄(C₄H₄O₆)₄.5H₂O. By mixing in solution equivalent quantities of thorium nitrate and tartaric acid a tartrate of the composition Th₃O₂(C₄H₄O₆)₄.20H₂O is precipitated; and this may be represented as the thorium salt of thorioditartaric acid, thus: [ThO(C₄H₄O₆)₂]₂Th.20H₂O. Various thoriotartrates have been prepared. Thus by saturating a boiling solution of potassium hydrogen tartrate with thorium hydroxide Cleve obtained K₉Th(C₄H₄O₆)₃, and Rosenheim, Samter, and Davidsohn have prepared ThO(C₄H₄O₆K)₂.8H₂O, ThO(C₄H₄O₆Na)₂.8H₂O, and ThO(C₄H₄O₆NH₄)₂.3H₂O, as well as the more basic salts

K₂(ThO)C₄H₄O₆.4H₂O and (NH₄)₂(ThO)C₄H₄O₆.4H₂O.

The constitution of these salts is probably analogous to that of tartar emetic, so that the hydroxylic hydrogen atoms of tartaric acid are replaced by ThO.