Cobalt blue bromide

A solution of chloro-diaquo-triammino-cobaltic bromide is blue in colour, and on the addition of hydrobromie acid the isomeric chloro-bromo-aquo-triammino-eobaltic bromide monohydrate, [Co(NH3) 3(H 20) ClBr]Br.H20, separates in brown needles even at temperatures below... 

That is, a mixture of 1-, 2-diaquo-tetrammino-cobaltic chloride and 1-, 2-diehloro-tetranimino-cobaltic chloride is formed. The aquo-salt is readily soluble in water but the diehloro-salt sparingly so. The last named forms intense blue crystals which are contaminated with small quantities of the praseo-salt, from which it may be freed by transforming it into the dithionate. The dithionate is practically insoluble, but the chloride may be regenerated from it by rubbing it with ammonium chloride. The bromide, the iodide, and the nitrate have all been prepared. 

The treatment of diorganozincs or organozinc halides with cobalt bromide in THF NMP mixtures provides blue solutions of organocobalt reagents, which have a half-life of several hours at -20 °C.25,26 Carbonylation reactions with these new cobalt reagents proceed well simply by bubbling carbon monoxide... 

Hydrazine forms68 a 2 1 complex with eobalt(ii) bromide Co(N2H4)Br2,2H20 and phenylhydrazine forms69 2 1 complexes with all cobalt(n) halides. The latter seem to be octahedral in the solid state but dissolve in acetone to give blue solutions with characteristic pseudotetrahedral electronic spectra. 

Methods for the determination of cobalt in soils using thiazolylblue tetrazolium bromide [6] and nitrotetrazolium blue chloride [7] were described. The examined samples were subjected to preliminary separation of the analyte with dithizone. The interference from Fe(IIl) could be masked with ascorbic acid [7]. 

Cobaltous bromide (6H2O) [85017-77-2 (XH2O), 7789-43-7 (anhydrous)] M 326.9 (6H2O), m 47 (dec), b 100 (dec), dj" 4.9. Crystallise it from water (ImL/g) by partial evaporation in a desiccator. The anhydrous salt is soluble in EtOH, Me2CO, MeOAc to form blue-coloured solutions. [Glemser in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol II p 1517 1965.]... 

Fig. 1. Chemical drawings of the most-commonly used intercalators in the development of electrochemical DNA biosensors (1) Cobalt(ll)-Tris-(1,10-phenanthroline), (2) Ruthenium(ll)-Tris-(1,10-bipyridine), (3) Methylene blue, (4) Meldola blue, (5) Ethidium bromide.

PROCEDURE Dissolve mixtures of cobalt(II) chloride and various quantities of sodium or potassium bromide and iodide in water. Iron(III) chloride can also be used. Use a paint brush to make water color paintings on paper (filter paper works very well). With some experimentation, water color paintings which encompass a wide variety of colors (yellow, pink, green, blue) can be made which appear when heated and disappear in a humid atmosphere.( to) These solutions can be kept for the next year, or, since they contain very little cobalt, disposal in the trash is appropriate. The salts can be washed off the paper and the cobalt recovered from the resulting solution. 

An interesting system is the methylene blue catalyzed oxidation of HS by O2 in a CSTR. Oscillation occurs over a narrow range of flow rates, and a mechanism has been proposed. Oscillations have also been found in the cobalt/bromide catalyzed oxidation of cyclohexanone by O2 in the electrochemical oxidation of HCHO and HCOOH/HCOO , and in the electrodissolution of copper in acidic chloride solution, and the anodic dissolution of nickel in aqueous sulfuric acid. °° Damped oscillations are predicted for reactions in stirred diaphragm cells. ... 

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