Lanthanide trichlorides solubilities

Early studies of the temperature variation of the solubilities of lanthanide trichlorides have already been mentioned. More recently, comprehensive data from —15° to + 50°C have been presented (259, 260) a representative selection is given in Table XVIII. Here and elsewhere, the dependence of solubility on temperature does not conform... 

All the solubilities so far mentioned have been presented in weight or concentration units. These may be converted via standard thermodynamic formulas into Gibbs free energies of solution. One group of authors, however, has preferred to present their data in this form, for YC13, LaClj, and six other lanthanide trichlorides (184). 

For qualitative information on relative solubilities of lanthanide trichlorides in ra-butanol and in water, see Asselin et al. (286). 

Solubilities of Lanthanide Trichlorides in Hexamethylphosphoramide (HMPA), Tributyl Phosphate (TBP), and Hexachlorobutadiene (HCB)... 

Strictly, the solubilities of salt hydrates in nonaqueous solvents, and of lanthanide trichlorides in 97% ethanol, mentioned in Section V,B,2,a,... 

Finally, in this section on alcohols, we should mention investigations in which the trichloride/alcohol systems are acknowledged to be not anhydrous. Solubilities of yttrium trichloride and of most of the lanthanide trichlorides have been determined in 96.8% ethanol over the temperature range 20-60°C (289), while the solubilities of the hydrates LaCl3-7H20 and CeCls-BHjO have been determined in an extensive range of alcohols at 25°C, with a few data at 35° and at 45°C (290). 

In view of the aforementioned difficulties, both of incompatibility of concentration units and of chemistry and accuracy, we have selected sets of data to illustrate trends in solubilities. Only one paper deals with a selection of trichlorides across the lanthanide series its results... 

Comparisons of solubilities of trichlorides, tribromides, and triiodides of the lanthanides in a variety of nonaqueous solvents can be found in a Russian review (310). Perhaps the widest range of solubilities of lanthanide(III) salts in nonaqueous media refers not to the trihalides but to the nitrates, whose solubilities in 31 solvents have been measured (312). Unfortunately, these measurements were carried out on the hexahydrates rather than anhydrous materials. 

In a subsequent study of reaction parameters, lanthanide ions were found to promote the selective reduction of conjugated aldehydes in the presence of noncon-jugated aldehydes in aqueous ethanol. Erbium trichloride was the preferred catalyst, usually where the solubility of cerium trichloride in solvents such as isopropyl alcohol was unfavorable (Gemal and Luche, 1981b). The authors described the interaction between the lanthanide and the intermediate substrate as a chelating effect . 

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