Manganese hydroxide, dehydration

EDA reacts readily with two moles of CS2 in aqueous sodium hydroxide to form the bis sodium dithiocarbamate. When aqueous ammonia and 2inc oxide (or manganese oxide or its hydrate) is used with a basic catalyst, the 2inc (or manganese) dithiocarbamate salt is isolated. Alternatively, the disodium salt can react with ZnSO or MnSO followed by dehydration in an organic solvent to yield the same salts (48—50). 

Also, careful dehydration of manganese(II) hydroxide, Mn(OH)2, under controlled conditions in the absence of air yields MnO. 

The Mn3+/Mn2+ couple is ostensibly pH independent, but we must bear in mind that manganese(III), in particular, will hydrolyze unless the acidity is very high, and both Mn(OH)3 and Mn(OH)2 will come out of solution in alkaline media. Small degrees of hydrolysis in solution have little impact on E°, but precipitation of hydroxides (and all metal hydroxides except those of the alkali metals and Ca, Sr, Ba, and Ra are poorly soluble in water) affects E° profoundly. Thus, in alkaline media, the electrode potentials (often called Eh by geologists, wherever [H+] is not the standard value) of Mn2+ and Mn3+ are controlled by the solubility products (Ksp) of Mn(OH)2 and Mn(OH)3, respectively. In practice, Mn(OH)3 tends to dehydrate to MnO(OH), so we consider the Mn2+(aq)/Mn(s) couple ... 

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