Cobalt(II) acetate

Cobalt(II) acetate is the cobalt salt of acetic acid. It is commonly found as the tetrahydrate Co(CH3CO2)2·4 H2O, abbreviated Co(OAc)2·4 H2O. It is used as a catalyst.

Cobalt(II) acetate
Names
IUPAC name
Cobalt(II) acetate
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.000.687
UNII
Properties
Co(C2H3O2)2
Molar mass 177.02124 g/mol (anhydrous)
249.08 g/mol (tetrahydrate)
Appearance Pink crystals (tetrahydrate)
intense red crystals (anhydrous)
Odor vinegar (tetrahydrate)
Density 1.705 g/cm3 (tetrahydrate)
Melting point 140 °C (284 °F; 413 K) (tetrahydrate)
Soluble
Solubility soluble in alcohol, dilute acids, pentyl acetate (tetrahydrate)
+11,000·10−6 cm3/mol
1.542 (tetrahydrate)
Hazards
Safety data sheet J.T. Baker MSDS
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
0
1
0
Lethal dose or concentration (LD, LC):
503 mg/kg (oral, rat)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Synthesis and structure

It may be formed by the reaction between cobalt oxide or hydroxide and acetic acid:

CoO + 2 CH3CO2H + 3 H2O → Co(CH3CO2)2·4 H2O

The tetrahydrate has been shown by X-ray crystallography to adopt an octahedral structure, the central cobalt centre being coordinated by four water molecules and two acetate ligands.[1]

Reactions and uses

Cobalt acetate is a precursor to various oil drying agents, catalysts that allow paints and varnishes to harden.[2] Cobalt(II) acetate reacts with salenH2 to give salcomine, a precursor to a transition metal dioxygen complex:[3]

Co(OAc)2 + salenH2 → Co(salen) + 2 HOAc

Safety

Cobalt salts are poisonous.[4]

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References
  1. Van Niekerk, J. N.; Schoening, F. R. L. (1953). "The crystal structures of nickel acetate, Ni(CH3COO)2·4H2O, and cobalt acetate, Co(CH3COO)2·4H2O". Acta Crystallogr. 6 (7): 609–612. doi:10.1107/S0365110X5300171X.
  2. John Dallas Donaldson, Detmar Beyersmann, "Cobalt and Cobalt Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a07_281.pub2
  3. Appleton, T. G. (1977). "Oxygen Uptake by a Cobalt(II) Complex". J. Chem. Educ. 54 (7): 443. doi:10.1021/ed054p443.
  4. MallBaker MSDS


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