Nomenclature
CAS number: 7789-43-7
Cobalt dibromide.
Br
2Co; mol wt 218.74.
Br 73.06%, Co 26.94%.
CoBr
2.
Description and references
Prepn of hexahydrate from CoCO3 and
HBr: Clark, Buchner, J. Am. Chem. Soc. 44, 230 (1922). Prepn of anhydr: eidem, loc. cit.; Watt et al., ibid. 77, 2752 (1955); Wydeven, Gregory, J. Phys. Chem. 68, 3249 (1964).
Properties
Bright green solid or lustrous green cryst leaflets.
mp 678° (under HBr and
N2); d425 4.909. Hygroscopic, forms hexahydrate in
air. Readily sol in water, methanol, ethanol, acetone, methyl acetate.Derivative
Hexahydrate.
Properties
Red to reddish-purple, deliquesc, prismatic crystals.
mp 47-48°. d425 2.46. Loses 4H2O at 100° giving the purple dihydrate,
and all H2O by 130°. Sol in water giving red or blue soln
depending on concn and temp, in methanol giving red soln, in ethanol,
acetone, ether, methyl acetate giving blue solns. Keep well closed.Use
Chiefly in hygrometers; also in catalysts for organic
reactions.