Cobalt (II) acetate

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Structural formula
Structural formula of cobalt (II) acetate
General
Surname Cobalt (II) acetate
other names
  • Cobalt (II) acetate
  • Cobalt acetate
Molecular formula C 4 H 6 CoO 4
Brief description
  • red to purple solid (anhydrous)
  • pink solid (tetrahydrate)
External identifiers / databases
CAS number
  • 71-48-7 (anhydrous)
  • 6147-53-1 (tetrahydrate)
EC number 200-755-8
PubChem 6277
Wikidata Q421198
properties
Molar mass
  • 177.02 g mol −1 (anhydrous)
  • 249.08 g mol −1 (tetrahydrate)
Physical state

firmly

density

1.7 g cm −3 (20 ° C, tetrahydrate)

Melting point

140 ° C (tetrahydrate)

solubility
  • easily in water (380 g l −1 at 25 ° C, tetrahydrate)
  • easily in acetic acid and pyridine
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
08 - Dangerous to health 09 - Dangerous for the environment

danger

H and P phrases H: 302-319-334-317-341-350i-360F-410
P: 201-261-280-284-304 + 340-308 + 313
Authorization procedure under REACH

particularly worrying : carcinogenic, toxic for reproduction ( CMR )

Toxicological data

503 mg kg −1 ( LD 50 ,  rat ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cobalt (II) acetate is a chemical compound from the group of cobalt compounds and acetates with the constitutional formula Co (CH 3 COO) 2 .

Extraction and presentation

The production of cobalt (II) acetate tetrahydrate by reaction of cobalt (II) oxide with acetic acid was first mentioned in 1777:

The water of crystallization was first determined in 1878 by H. Stallo. The usual method of preparing the tetrahydrate today is the reaction of cobalt (II) carbonate with acetic acid.

Anhydrous cobalt acetate can be made by reacting cobalt (II) nitrate with acetic anhydride .

properties

Cobalt (II) acetate (left) and cobalt (II) acetate tetrahydrate (right).

The tetrahydrate crystallizes in the monoclinic crystal system in the space group P 2 1 / c (space group no. 14) with the lattice parameters a = 477.4  pm , b = 1184.3 pm, c = 829.0 pm and β = 93.14 °. In the unit cell contains two formula units . The crystals are isomorphic to nickel (II) acetate . Template: room group / 14

There is also a basic cobalt (II) acetate with the composition Co 5 (OH) 2 (CH 3 COO) 8 . It crystallizes as a dihydrate and is formed during the decomposition of cobalt (III) acetylacetonate.

When ammonium chromate is reacted with cobalt (II) acetate, a double salt with the composition (NH 4 ) 2 Co (CrO 4 ) 2 · 6H 2 O is formed, which crystallizes out in the form of brown-yellow prisms .

When heated, cobalt (II) acetate tetrahydrate first gives off its water of crystallization. The dehydration is complete at 150 ° C and takes place in two stages - a hemihydrate Co (CH 3 COO) 2  · 0.5 H 2 O is formed as an intermediate . When the anhydrous compound is heated further, a basic acetate with the stoichiometric composition Co ( OH) (CH 3 COO). The end product of the decomposition is elemental cobalt in a hydrogen atmosphere, cobalt (II) oxide in a nitrogen atmosphere and cobalt (II, III) oxide Co 3 O 4 in the air .

use

Cobalt (II) acetate is used as a bleaching and drying agent for paints and varnishes and as a catalyst in the production of adipic acid .

Individual evidence

  1. ↑ a b c d e f g h i Entry on cobalt (II) acetate in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
  2. ↑ a b E. Späth: About the action of acetic anhydride to nitrates , in: Monatshefte fur Chemie , 1912 , 33  (3), pp 235-251; doi : 10.1007 / BF01519254 .
  3. ↑ Entry on Cobalt di (acetate) in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
  4. ↑ Entry in the SVHC list of the European Chemicals Agency , accessed on December 6, 2019.
  5. ^ CF Wenzel: Doctrine of the kinship of the body , Verlag Gerlach 1777, p. 194 ( full text in the Google book search).
  6. ^ FW Clarke: Some determinations of specific weights , in: Reports of the German Chemical Society , 1878 , 11  (2), pp. 1504–1507; doi : 10.1002 / cber.18780110261 ; Full text at gallica .
  7. ↑ a b c J. Matthes: Crystalline cobalt (II) carboxylates from the gas phase , University of Bonn, dissertation 2009, pp. 7–8; Full text .
  8. ↑ TO Sobolev, EB Miminoshvili, KE Miminoshvili, TN Sakvarelidze: Cobalt diacetate tetrahydrate , in: Acta Cryst. , 2003 , E59  (10), m836-m837; doi : 10.1107 / S1600536803019093 .
  9. ↑ a b J. N. Van Niekerk, FRL Schoening: The crystal structures of nickel acetate, Ni (CH 3 COO) 2 · 4 H 2 O, and cobalt acetate, Co (CH 3 COO) 2 · 4 H 2 O , in: Acta Crystallographica , 1953 , 6  (7), pp. 609-612; doi : 10.1107 / S0365110X5300171X .
  10. ^ R. Kuhlman, GL Schimek, JW Kolis: An Extended Solid from the Solvothermal Decomposition of Co (acac) 3 : Structure and Characterization of Co 5 (OH) 2 (O 2 CCH 3 ) 8 2H 2 O , in: Inorg . Chem. , 1999 , 38  (1), pp. 194-196; doi : 10.1021 / ic9802855 .
  11. ^ R. Abegg, F. Auerbach: Handbuch der inorganic Chemie , Vol. 4, S. Hirzel Verlag, 1921, p. 400; Full text .
  12. ↑ RW Grimes, AN Fitch: Thermal decomposition of cobalt (II) acetate tetrahydrate studied with time-resolved neutron diffraction and thermogravimetric analysis , in: Journal of Materials Chemistry , 1991 , 1 , pp. 461-468; doi : 10.1039 / JM9910100461 .
  13. ↑ a b T. Wanjun, C. Donghua: Mechanism of thermal decomposition of cobalt acetate tetrahydrate , in: Chemical Papers , 2007 , 61  (4), pp. 329-332; doi : 10.2478 / s11696-007-0042-3 .
  14. ↑ a b M. A. Mohamed, SA Halawy, MM Ebrahim: The non-isothermal decomposition of cobalt acetate tetrahydrate. A kinetic and thermodynamic study , in: Journal of Thermal Analysis and Calorimetry , 1994 , 41 , pp. 387-404; doi : 10.1007 / BF02549322 .