Beiträge zur Chemie des Erbiums und Didyms

The Basicity Characteristics of Scandium, Yttrium, and the Rare Earth Elements.

“…Excellent summaries of early work have been given by Urbain (401), who listed the elements in order of decreasing basicity as La, Di, Ce(III), Y, Gd, Sm, Tb, Ho, Er, Tm, Yb, Sc and particularly by Bohm (33), who gave the order as La, Pr, Nd, Gd, Sm, Y, Tb, Ho, Er, Tm, Yb, Sc, Ce(IV) and pointed out that while the order lanthanum, praseodymium, neodymium appeared definite, the remainder of the series was in doubt. These series were based upon such observations as the following: the precipitation of didymium before lanthanum (29); the precipitation of samarium before gadolinium (16, 24, 109); precipitation of the erbium earths, terbium, and yttrium in that order (170); the grouping of lanthanum, didymium, samarium, yttrium, and terbium in the more basic fractions with erbium, holmium, thulium, ytterbium, scandium, and cerium in the less basic ones upon ammonia precipitation (231); increase of basicity in the series ytterbium, erbium, holmium, terbium as shown by ammonia precipitation (261); precipitation of didymium in preference to lanthanum with magnesium oxide (310); precipitation of samarium before didymium with ammonia (90); precipitation of samarium, didymium, and lanthanum in that order with ammonia (94); concentration of yttrium in the more basic fractions in ammonia separations (107, 305); and precipitation in order of the colorless yttrium earths, terbium, erbium, samarium, neodymium, and praseodymium by ammonia (309).…”

“…Reasoning that ammonia is too strongly basic to effect a rapid separation of the weakly basic erbium earths, Krüss (231) investigated a number of more weakly basic substituted ammonias. Of these aniline proved to be best, and a procedure involving treatment of a neutral chloride solution in 50 per cent ethanol at 90°C.…”

“…As experimental evidence for the relatively high basicities of the oxides of these elements, one can cite the ease with which even the strongly ignited oxides of all but scandium dissolve in acids (66,79,250,263,285,305,416); dissolve in ammonium salt solutions with the liberation of ammonia (20,21,45,244,250,263,343); dissolve in aniline hydrochloride solutions (233); react with such hightemperature acids as ammonium salts (5,146,147,181,351,352,394,450), borax (31,154), metaphosphate (31), and alkali bisulfate (231,363) or pyrosulfate (11, 212); and absorb atmospheric carbon dioxide (114,250,263,278,285). To these can be added the comparatively high water solubilities and precipitation pH values of the hydrous oxides and hydroxides (64,65,74,167,222,297,327,361,389,398), the tendencies of at least some of the oxides to slake with water (244, 250, 278, 285), the absorption of carbon dioxide by hydrous lanthanum (12,...…”