Group-IIA Metals and Their Alloys

As a result of their reactivity, particular attention must be given to preparation and purification of the metals, the conditions under which the metals, alloys and compounds are handled and the choice of material for the containment vessel. Ultrapure group-IIB metals may be used without further purification, but it is advisable to purify the group-IIA metals by a multidistillation process, the final distillation preferably being carried out in situ. The reactants and products are best handled in an atmosphere of a purified inert gas, usually He or Ar (N2 cannot be used because of the ready formation of group-IIA metal nitrides) alternatively, they can be handled under vacuum or, in rare cases, under halide fluxes. The containment vessel is normally fabricated from a refractory. 

Copper-catalysts promoted with i) other group VIA or VIIIA metals and ii) alcaline or alcaline earth elements (IA or IIA) are used for selective hydrogenation of various organic compounds (1). Moreover Cu(Co) Zn-Al catalysts were extensively studied for the synthesis of methanol and of light alcohols (2,3). More recently, due to the development of fine chemical processes, detailed studies of copper catalysts were carried out in order to show, like for noble metals, the effect of supports (SMSI), of promoters and of activation-on metal dispersion or reduction, on alloy formation... For example modified copper catalysts are known for their utilization in the dehydrogenation of esters (4-6), in the hydrolysis of nitriles (7), in the selective hydrogenation of nitriles (8), in the amination of alcohols (9)... 

Barium is a member of the alkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely allied series in which the chemical and physical properties of the elements and their compounds vary systematically with increasing size, the ionic and electropositive nature being greatest for barium (see Calcium and calcium alloys Calcium compounds Strontium and STRONTIUM COMPOUNDS). As size increases, hydration tendencies of the crystalline salts increase solubilities of sulfates, nitrates, chlorides, etc, decrease (except fluorides) solubilities of halides in ethanol decrease thermal stabilities of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

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