Scandium hydroxide

Porphyrin, octaethyl-, scandium hydroxide complex cyclic voltammetry, 4, 399 <73JA5140)... 

Like the hydroxides of the Rare earth, scandium hydroxide, Sc(OH)3, is precipitated by addition of alkalies to solutions of scandium salts however, the latter is precipitated at pH 4.9, while the former require pH 6.3 or more, a property which is utilized in one method of separation. Upon heating the hydroxide (or certain oxyatid salts), scandium oxide. Sc>C>3 is produced. Scandium hydroxide is less acidic than aluminum hydroxide, requiring boiling KOH solution to form the complex potassium compound, K2[Sc(OH)5 H 0] 3H 0. 

The scandium values may be directly recovered from the eluate by addition of ammonium hydroxide and consequent precipitation of scandium hydroxide at pH above 7. A preferred technique is the precipitation of scandium oxalate it results in a purer product because many of the metallic impurities which co-precipitate as the... 

Scandium (Sc, at. mass 44.96) occurs in its compounds exclusively in the III oxidation state. Some of its chemical properties resemble those of the lanthanides and yttrium. Scandium hydroxide Sc(OH>3 precipitates at a pH as low as 4.8 and dissolves in alkaline medium in this respect scandium resembles aluminium. 

Scandium hydroxide Sc(OH), 17674-34-9 96.978 col amorp solid I EIjO s dil acid... 

Addition of scandium hydroxide to aqueous trifluoroacetic acid gives Sc(0H)(02C CF3)a,2H20 in high yield at 230—330 °C the anhydrous material decomposes according to the equation ... 

The hydroxide and oxide phases that exist for scandium(III) include scandium hydroxide, Sc(OH)3(s), which likely has both amorphous and crystalline forms, ScOOH(s), and scandium oxide. It would be expected that the amorphous hydroxide is the most soluble and Sc203(s) the least. There have been few studies that have examined the solubility of these phases. None of the hydroxide or oxide phases of scandium are known to form naturally, with scandium present, as a major component, in eight mineral phases only (Wood and Samson, 2006). Moreover, there is much conjecture over which phases have actually been studied as well as their crystallinity (Baes and Mesmer, 1976 Wood and Samson, 2006). This review has selected data for both the hydroxide and oxide phases, based largely on the similarity in the stabilities obtained for the phases studied. Baes and Mesmer (1976) provided a stability constant for ScOOH(s) on the basis of data provided by Schindler (1963), but it is believed that the phase actually studied was Sc(OH)3(s) given the similar solubility found in the studies of Feitknecht and Schindler (1963) and Shkolnikov (2009). 

Ivanov-Emin, Nisel son andIvolgina (1960) andIvanov-Eminetal. (1968) studied the solubility of well-crystallised scandium hydroxide in solutions of sodium and potassium hydroxide. They showed that the solubility increased linearly with an increase in the hydroxide concentration. The stability of the solubility reaction should only be slightly dependent on ionic strength and medium and, as such, Ivanov-Emin et al. found a very similar stability constant in both bases. The constant obtained should be similar to that at zero ionic strength and the average is... 

Ivanov-Emin, B.N., Borzova, L.D., Zaitsev, B.E., and Mekes Fisher, M. (1968) Solubility of scandium hydroxide in potassium hydroxide solutions. Russ. J. Inorg. Chem., 13, 1156-1157 (English translation). Ivanov-Emin, B.N., Egorov, A.M., Romanuk, V.I., and Siforova, E.N. (1970) Constants... 

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