Nutrition cobalt ions

Properties Steel-gray, shining, hard, ductile, somewhat malleable metal ferromagnetic, with permeability two-thirds that of iron has exceptional magnetic properties in alloys. D 8.9, mp 1493C, bp 3100C. Attacked by dilute hydrochloric and sulfuric acids, soluble in nitric acid. Corrodes readily in air. Hardness cast 124 Brinell, electrodeposited 300 Brinell. An important trace element in soils and necessary for animal nutrition. Cobalt has unusual coordinating properties, especially the trivalent ion. Noncombustible except as powder. 

Although cobalt ions are found in both the (II) and (III) oxidation states, the most important biological compound of cobalt is vitamin B12 or cobalamin where the Co(III) form is present (256) (Fig. 6.10). Cobalamin or related substances are important biological compounds that are involved in a great variety of activities, particularly in bacteria. Vitamin B12 is also necessary in the nutrition of humans and probably of most animal and plant species. It is of critical importance in the reactions by which residues from carbohydrates, fats and proteins, are used to produce energy in living cells. Pernicious anemia is a severe disease in elderly people. This disease is usually accompanied in mammals by the increased excretion of methylmalonic acid in the urine. Today it is effectively controlled by a 100 /ig injection of vitamin B,2. 

The commonly used transition metal compounds in commercial oxo-biodegradable plastics are manganese, iron, cobalt and nickel. None of these have been shown to be toxic and until recently have not been in national lists of dangerous substances. All the above transition metal ions, which are required in human nutrition, are absorbed from foodstuffs and water. They are therefore considered to be essential minerals [70] required in oxygen transport systems. The non-toxicities of iron, which is present in haemoglobin, catalase and peroxidases and of manganese, required for manganese peroxidase, have not been questioned. 

---