Cobalt iodate

Cobalt Iodate, Co(I03)2, was known to Rammelsberg 2 in 1838, and was further studied by Fullerton 3 and Ditte,4 the last-named investigator claiming to have prepared the anhydrous salt, and salts with 2, 3, 4, and 5 molecules of water, whilst Fullerton describes a hexahydrate. 

Anhydrous cobalt iodate yields microscopic needles, blue-violet in colour, and which on heating become dark blue in colour, but regain their original hue on cooling. Below 200° C. decomposition sets in, iodine and oxygen being evolved. 

The various solubilities of the hydrates of cobalt iodate at different temperatures are as follow5 ... 

Cobalt Copper Acetylene, hydrazinium nitrate, oxidants Acetylene and alkynes, ammonium nitrate, azides, bromates, chlorates, iodates, chlorine, ethylene oxide, fluorine, peroxides, hydrogen sulfide, hydrazinium nitrate... 

Unexpected uniformities observed in the impact-sensitivities of a group of 22 amminecobalt oxosalts are related to kinetic factors during the initiation process [6], A series of ammine derivatives of cadmium, cobalt, copper, mercury, nickel, platinum and zinc with (mainly) iodate anions was prepared and evaluated as explosives [7], Earlier, ammine and hydrazine derivatives of cadmium, cobalt, copper and nickel with chlorate or perchlorate anions had been evaluated as detonators. Dihydrazinecopper(II) chlorate had exploded when dried at ambient temperature [8],... 

Bis(l,2-diaminoethane)diaquacobalt(III) perchlorate, 1793 Bis(l,2-diaminoethane)dichlorocobalt(III) chlorate, 1786 Bis(l,2-diaminoethane)dichlorocobalt(III) perchlorate, 1787 c/ s-Bis(l,2-diaminoethane)dinitrocobalt(III) iodate, 1784 Bis(l,2-diaminoethane)dinitrocobalt(III) perchlorate, 1784 Bis(l,2-diaminoethane)hydroxooxorhenium(V) perchlorate, 1791 Bis(l,2-diaminopropane)-c/5-dichlorochromium(III) perchlorate, 2613 Bis(diethylenetriamine)cobalt(III) perchlorate, 3106 l,2-Bis(diphenylphosphino)ethanepalladium(II) perchlorate, 3864 Bis(hydrazine)diperchloratochromium(III) perchlorate, 4128 Bis(hydrazine)nickel perchlorate, 4069 Bis(hydrazine)tin(II) chloride, 4070 Bis(hydroxylamine)zinc chloride, 4067... 

C. F. Rammelsberg also prepared what he thought to be a monohydrated nickel iodate analogous with his cobalt salt F. W. Clarke similarly reported a hexahydrated nickel iodate, and A. Ditte, green prismatic crystals of trihydrated nickel iodate. 

Fio. 23.—Solubility Curves of the Cobalt Fio. 24.—Solubility Curves of the Iodates. Nickel Iodatea. 

C. P. Rammelsberg prepared what appears to be nickel tetrammino-iodate, Ni(I03)2.4NH3, as a pale blue crystalline powder, by the addition of alcohol to a soln. of nickel iodate in ammonia he also prepared a similar cobalt tetrammino-iodate, Co(I03)2.4NH3. P. Ephraim and A. Jahnsen prepared trihydrated nickel pentammino-iodate, Ni(I03)2.5NH3.3H20, in reddish-violet columnar crystals, and from it they obtained pale violet crystals of nickel pentammino-iodate, Ni(I03)2.5NH3, of sp. gr. 2-97, and with a dissociation press, of 179 mm. at 53° 365 min. at 65° 670 at 77° and 905 mm. at 79°. The ammino-iodates do not explode when heated in open tubes, but they do so in closed tubes between 210° and 219°. The mol. vol. of the pentammino-salt is 166 2, and the mol. vol. of each NH3 is 17 1. The heat of formation of the pentammine is 12-5 Cals. 

C. F. Rammelsberg failed to prepare a cobalt periodate, but always obtained a mixture of oxide and iodate. 

In the absence of air, the corresponding cobalt [Pg.222]

Compounds containing the cation [Co(NH3)6NO]++ are obtained when aqueous cobalt(II) salt solutions containing ammonia are saturated with nitrogen(II) oxide.1 These compounds are either black or pink, depending upon the conditions used in their preparation. The black chloride and iodate are formed in the absence of air,2-4 whereas many members of the pink series are obtained in the presence of air.2-4 The method of preparation for the black chloride described here is a composite of those recommended by various authors1-5 and gives a product of considerable stability. The same reaction, using cobalt(II) nitrate, when run in the presence of air and at room temperature, may be used for the preparation of the pink nitrate. This may be converted into the pink chloride by treatment with concentrated hydrochloric acid.3... 

The anhydrous salt may be obtained by maintaining for a prolonged period at 80° to 90° C. a mixed solution of cobalt nitrate and Alkali iodate in the presence of free nitric acid. It is also formed at ordinary temperatures by mixing saturated solutions of cobalt nitrate and alkali iodate and agitating with a glass rod the flocculent, rose-coloured, hydrated precipitate, when it yields the blue-violet anhydrous compound. The salt is also produced by heating the same solutions from two to three hours in a glass tube at 120° C. 

The dihydrate, Co(IOs)a. 2HaO, is obtained by mixing equivalent amounts of cobalt nitrate and alkali iodate (or free iodic acid) in ten times their weight of water and allowing to crystallise at 30° C. Microscopic crystals of lilac hue are obtained, which are the stable form of the salt up to 68° C.. 

Schug and Gilmore (128) found that acid iodate as an oxidant gave no cobalt(II) by products (cobalt(II) often catalyses loss of optical activity from cobalt(III) complexes) and so in configurational correlations (129) this oxidant was employed. 

Under given conditions, passivity is attained with increasing readiness in the order iron, cobalt, nickel iron is much more difficult to render passive than is nickel in a particular electrolyte. Metals of the iron group become passive more readily in alkaline than in acid solutions, and oxidizing agents, e.g., iodate, bromate, chlorate, chromate and nitrate, favor passivity chloride ions markedly inhibit the onset of passivity. Increase of temperature increases the c.d. required for the anode to become passive under a given set of conditions. 

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