Cobalt powders reactivity

Cobalt represents an interesting contrast to the many activated metal powders generated by reduction of metal salts. As will be seen, the cobalt powders are highly reactive with regard to several different types of reactions. However, in contrast to the vast majority of metals studied to date, it shows limited reactivity toward oxidative addition with carbon halogen bonds. 

Subcategory A encompasses the manufacture of all batteries in which cadmium is the reactive anode material. Cadmium anode batteries currently manufactured are based on nickel-cadmium, silver-cadmium, and mercury-cadmium couples (Table 32.1). The manufacture of cadmium anode batteries uses various raw materials, which comprises cadmium or cadmium salts (mainly nitrates and oxides) to produce cell cathodes nickel powder and either nickel or nickel-plated steel screen to make the electrode support structures nylon and polypropylene, for use in manufacturing the cell separators and either sodium or potassium hydroxide, for use as process chemicals and as the cell electrolyte. Cobalt salts may be added to some electrodes. Batteries of this subcategory are predominantly rechargeable and find application in calculators, cell phones, laptops, and other portable electronic devices, in addition to a variety of industrial applications.1-4 A typical example is the nickel-cadmium battery described below. 

The reactivity of metal phosphide cations [MPJ+, and anions [MPJ , may also be studied in the gas phase. Laser ablation of mixtures of cobalt or nickel metal powders with red phosphorus gave a range of anions M PJ and cations [MPJ+ (185). The anions were unreactive, but the cations have been reacted with several neutral molecules. The ions [MPJ+, where M = Co, Ni and x = 2,4, 8, undergo five types of reactions. 

Oxidizer, Poison, Corrosive SAFETY PROFILE Poisonous and corrosive. Very reactive, a powerful oxidizer. Explosive or violent reaction with organic materials, water, acetone, ammonium halides, antimony, antimony trichloride oxide, arsenic, benzene, boron, bromine, carbon, carbon monoxide, carbon tetrachloride, carbon tetraiodide, chloromethane, cobalt, ether, halogens, iodine, powdered molybdenum, niobium, 2-pentanone, phosphoms, potassium hexachloroplatinate, pyridine, silicon, silicone grease, sulfur, tantalum, tin dichloride, titanium, toluene, vanadium, uranium, uranium hexafluoride. 

Cobalt is a moderately reactive element. It combines slowly with oxygen in the air, but does not catch fire and burn unless it is in a powder form. It reacts with most acids to produce hydrogen gas. It does not react with water at room temperatures. 

The reactivity of the catalyst is enhanced by azeotropic drying of the cobalt complex before use, thus allowing the reaction of sterically hindered and silyl-substituted alkynes. Good reactivity between norbornadiene and disubstituted alkynes (yields in homo-Diels-Alder adducts ca. 85%) is also achieved by adding zinc powder to cobalt iodide/triphenylphosphane catalysts. " ... 

In an original approach, reactive metallic powders of copper, cobalt, and zinc have been generated by pulsed sonoelectrochemical reduction. Zinc produced in this manner effects allylation reactions of carbonyl compounds (p. 223) in higher yields than commercial powders... 

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