Cobalt dibromide

When the cobalt salt of carboxylic acid and bromide ion are dissolved in acetic acid, a cobalt bromide complex is formed instantaneously. For cobalt dibromide a pronounced induction period was observed, but adding sodium acetate eliminates entirely the induction period, suggesting that cobalt monobromide is responsible for the catalysis. 

However, when a strong bromide such as calcium bromide is used, the oxidation rate reaches a maximum (Figure 8) and decreases as the ratio is increased, probably owing to the formation of inactive cobalt dibromide. 

This catalyst3 is prepared in quantitative yield by refluxing 200 ml. of benzene solution containing 10 g. (0.046 mole) of anhydrous cobalt dibromide and 24.4 g. (0.092 mole) of triphenyl phosphine. A color change is observed, and the blue-green solid that precipitates on cooling to room temperature is filtered and dried. This catalyst, stored in a dry atmosphere, appears to be active indefinitely. 

COBALT DIBROMIDE (7789-43-7) Br2Co Noncombustible solid. A mild acid. Reacts with acetylene, bases, amines, amides, and inorganic hydroxides strong oxidizers. Thermal decomposition releases highly toxic bromine fumes. Cobalt is a known animal carcinogen. 

COBALT DIBROMIDE (7789-43-7) Reacts with acetylene, strong oxidizers. 

Cobalt bromide Cobalt bromide (CoBr2) Cobalt dibromide Cobalt(ll) bromide Cobaltous bromide EINECS 232-166-7 HSDB 998. Solid mp = 678 d - 4,909 soluble in H2O, organic solvents. Mechema Chemicals Ltd. 

CoBr2 COBALT DIBROMIDE 534 Cr02 CHROMIUM DIOXIDE 570... 

Synonyms Cobalt bromide Cobalt (II) bromide Cobalt dibromide Cobaltous bromide... 

Cobalt dibromide. See Cobalt bromide (ous) Cobalt dichloride. See Cobalt chloride (ous) Cobalt dichromium tetraoxide. See Cobalt chromate (ous)... 

Woyakowska A, Piinska S, Josiak J, Krzyzak E (2006) Electrical conductivity of molten cobalt dibromide + potassium bromide mixtures. J Chem Eng Data 51 1256-1260... 

Cobalt dichtoride and dibromide react highly violently with sodium and potassium. 

Cobalt(I) salen has been employed as a catalyst for the reduction of the following species benzal chloride [159] benzotrichloride [160] 1-bromobutane, 1-iodobutane, and 1,2-dibromobutane [161] iodoethane [162], benzyl chloride [163], and ethyl chloroacetate [164]. Rusling and coworkers have investigated the use of cobalt(I) salen, as well as vitamin Bi2s and cobalt(I) phthalocyanine, in both homogeneous phase and bicontin-uous microemulsions for the catalytic reduction of vicinal dibromides [165] and... 

Control experiments establish that the initial process converting the dibromide 275 to 276 takes place in two steps with E1/2 for extrusion of the first and second axial ligands occurring at —0.36 and —1.08 V, respectively [75]. After reaction with the alkyl halide, the resulting octahedral complex 277 is further reduced in the range of -1.4 to -1.7 V to form a cobalt (II) complex which decays via the addition of an additional electron, cleavage of the C-Co and Co-Y bonds, and reaction with the Michael acceptor. 

Ethylenediaminetetraacetic acid, analogs, complexes of, 3 277 chelation by, 3 276-277 cobalt complex of, 3 281 complexes, 3 277-278 formation constant of, 3 273-274 -nickel, 3 17-18 stability of, 3 266-267 reaction with metal ions, 3 62 Ethylene dibromide, irradiation of, 5 196 4,5-Ethylenedithio-1,3-dithiole-2-thione based supramolecular complexes, 46 200-204 Ethylene glycol, 32 4... 

Ethanedithiol has been prepared from ethylene dichloride or ethylene dibromide and alcoholic potassium hydrosulfide from ethylene dibromide and alcoholic sodium hydrosulfide from ethylene dichloride or ethylene dibromide and alcoholic sodium hydrosulfide under pressure from ethylene dibromide and thiourea and by the catalytic hydrogenation with cobalt trisulfide or nickel-on-kieselguhr of the mixture resulting from the reaction of ethylene and sulfur. The present method is a modification of one described by Mathias. ... 

Auric bromide, AuBr3.—The bromide is formed in aqueous solution by the action of water on gold dibromide.14 It can be obtained in the solid state from the same source by the action of moist ether, the aurous bromide formed remaining undissolved, and auric bromide being left on evaporation of the dried ether solution. It is also produced by the interaction of aqueous bromine and gold,16 as well as by the action of solutions of such perbromides as cobalt tribromide, manganese tetrabromide, and ferric bromide on the metal.16 The aqueous solution and the crystals deposited from it have a scarlet-red colour, but the pure salt contained from solution in ether is a dark-brown... 

Br3CoN40C4Hig H2O, Cobalt(III), aquabro-mobis( 1,2-ethanediamine)-, dibromide, cis-, monohydrate, 21 123 Br4GaNCgH2o, Gallate(l - ), tetrabromo-, tetraethylammonium, 22 141 Br4GaNCi6H3g, Gallate(l - ), tetrabromo-, tetrabutylammonium, 22 139 Br4H26Ng02Rh2, Rhodium(III), di- jL-hy-droxo-bis[tetraamine-, tetrabromide, 24 226... 

Rusling and coworkers have carried out extensive studies of the use of electrogenerated cobalt(I) complexes (including cobalt(I) salen, vitamin Bi2s, and cobalt(I) phthalo-cyanine) as catalysts both in homogeneous phase and in bicontinuous microemulsions [384] for the reductions of 1,2-dibromoethane and 1,2-dibromobutane [385], the debromi-nation of alkyl vicinal dibromides [386], the dechlorination of DDT [387], the reductions of 1-bromobutane, 1-bromododecane, and ran5-l,2-dibromocyclohexane [388,389], and the reduction of benzyl bromide [390]. 

Alkylmagnesium fluorides.3 Alkylmagnesium fluorides have been prepared for the first time by reaction of alkyl fluorides (hexyl fluoride was used for the most part) with magnesium at reflux temperature in THF in the presence of various catalysts. Of these, iodine (4%) was found to be most effective the yield of Cirignard reagent was 95%, obtained in 6 days. Other less effective catalysts are cobalt chloride, bromine, ethylene dibromide, ethyl bromide. 

Werner prepared cis- and tazns-dibromobis(l, 2-ethanediamine)cobalt(III) bromide by reacting the carbonato bromide with concentrated hydrobromic acid.2 In the cold, the cis isomer resulted the trans isomer was obtained by heating the mixture. The reaction proceeds via ds-aquabromobis(l, 2-ethanedi-amine)cobalt(III) dibromide which can be isolated by this route. In our hands, the preparations, as originally described, are not reproducible. The reaction times and yields are variable, depending too critically on the conditions for one not intuitively skilled in the art to consistently obtain the desired cis or trans form. However, the syntheses described here for the cis and trans dibromo complexes and based on this reaction are reproducible if one adheres closely to the procedures. 

In addition to the cis and trans dibromo complexes, the syntheses of c/s-aqua-bromobis(l,2-ethanediamine)cobalt(III) dibromide monohydrate and trans-aquabromobis(l,2-ethanediamine)cobalt(III) dithionate monohydrate are described. It is of historical interest that of the hundreds of cis/trans isomeric pairs of diacidobis(l,2-ethanediamine)cobalt(III) complexes known to Werner,3 the trans isomers in the classical aquahalo series eluded him. The procedures described here for their isolation are a modification of much later works, 8 in which the more soluble trans complexes were obtained pure as their sulfate salts by fractional crystallization of cis/trans mixtures. The syntheses of cis-[Co(en)2(OH2)Cl]S04-2H201-9 and ds-[Co(en)2(0H2)Cl]Br2"H209 are described in previous volumes of this series. The preparation of frans-aquachloro-bis(l, 2-ethanediamine)cobalt(III) dithionate monohydrate is given here to complete the series. 

Br3CoN40C4HI( H20, Cobalt (III), aquabro-mobis( 1,2-ethanediamine)-, dibromide, cis-monohydrate, 21 123... 

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