Reactions with Calcium, Strontium, and Barium

Reactions of Unsaturated Organic Molecules 10.2.3.3.2. Reactions with Calcium, Strontium, and Barium. 

Lead peroxide is even more active than the oxide. It reacts violently with sulphur and sulphides. When it is ground up with sulphur, the mixture combusts. With hydrogen sulphide, the reaction is very exothermic and causes peroxide to incandesce and hydrogen sulphide to combust. Finally, it reacts violently with calcium, strontium and barium sulphides on heating. 

It is also possible to isolate bis(carbene) complexes involving the heavier alkaline earth metals. Thus, the reaction of two equivalents of 4 (R = Me or (Bu, R = H) with calcium, strontium and barium bis(trimethylsilyl)amides [M N(SiMe3)2 2(thf)2] (M = Ca, Sr, Ba) resulted in the displacement of two thf molecules to afford the corresponding biscarbene species, 19 (19). The solubilities and stabilities of these complexes were found to decrease from calcium to barium. 

Carbene complexes of alkaline earth metal amides and metallocenes have also been reported. Reaction of calcium, strontium, and barium bis(trimethylsilyl)amides [M(N(SiMe3)2 2(thf)2] (M = Ca, Sr, Ba) with two equivalents... 

OC-Hydroxycarboxylic Acid Complexes. Water-soluble titanium lactate complexes can be prepared by reactions of an aqueous solution of a titanium salt, such as TiCl, titanyl sulfate, or titanyl nitrate, with calcium, strontium, or barium lactate. The insoluble metal sulfate is filtered off and the filtrate neutralized using an alkaline metal hydroxide or carbonate, ammonium hydroxide, amine, or alkanolamine (78,79). Similar solutions of titanium lactate, malate, tartrate, and citrate can be produced by hydrolyzation of titanium salts, such as TiCl, in strongly (>pH 10) alkaline water isolation of the... 

Calcium, strontium, and barium react vigorously at 25°C. The less easily oxidized beryllium and magnesium show no observable reaction with water at 25°C, although magnesium reacts with boiling water. Table 18.7 summarizes various properties, sources, and preparations of the alkaline earth metals. 

The lowest rate coefficient is associated with (19). The reaction has also been studied using calcium, strontium and barium salts at pH 12.4 in the second-order region . The rates are in the orders Na" " < Ca ", Ba " > Ca > Sr " ". 

Heterometallic alkoxides of calcium, strontium, and barium with transition or posttransition metals have been formed by reactions with the preformed alkoxides (e.g., Table 8, Equations (8a) and (8b)). A variation on this approach generates the Group 2 alkoxides in situ by reaction of the metal with an alcohol and/or another alkoxide (e.g.. Table 8, Equations (9a) and (9b)). " " ... 

Catalysts Promoted with Calcium, Strontium, or Barium. The addition of these elements has been studied by two groups of workers. Spath and co-workers have added relatively large amounts of promoter, while Carberry and co-workers have studied catalysts containing trace amounts of calcium or strontium. When added as the peroxide, which is converted to the carbonate under reaction conditions, Spath et al. have shown that barium has two effects.Apart from stabilizing the particulate structure of the unsupported catalyst, a thin layer of barium carbonate is formed on the surface of the silver particles. A similar layer is also formed by the addition of calcium or strontium compounds which are convertible to carbonate. When the elements are added directly as the carbonate this layer is not formed. 

Observe the reactions of the calcium, strontium, and barium ions with oxalate ions. 

The hydrolytic ability of hydrochloric acid may be affected by salts present in the reaction mixture. The effect may be based on salting out of the hydrolysis products from the reaction mixture. For instance, magnesium and ammonium sulfates showed such an effect.117 Zinc and cadmium cations, as well as acetate and sulfate anions, decreased the hydrolysis rate with 0.1 M hydrochloric acid, whereas calcium, strontium, and barium ions exerted no effect.141 Neither copper metal, stainless steel, tin, nor sulfur dioxide impeded the hydrolysis with a solution of 0.03-0.05 M hydrochloric acid.142 There is a report143 that traces of metal salts affect the rate of hydrolysis but there are also contradicting findings144 145 that... 

Calcium, strontium, and barium also react with aqueous acid solutions to produce hydrogen gas. However, because these metals also attack water, two different reactions will occur simultaneously. 

The reactions of alkaline earth metals with water vary considerably. Beryllium does not react with water magnesium reacts slowly with steam and calcium, strontium, and barium react vigorously with cold water. 

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