Cobalt(II) acetate
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 476996050
| ImageFile1 = Nickel(II)-acetate-tetrahydrate-3D-balls.png
| ImageFile2 = Octan kobaltnatý.JPG
| ImageSize =
| ImageName = Cobalt(II) acetate
| IUPACName = Cobalt(II) acetate
| OtherNames =
|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 6041
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 3XC4P44U7E
| UNII1_Ref = {{fdacite|correct|FDA}}
| UNII1 = 7648Z91O1N
| UNII1_Comment = (tetrahydrate)
| InChI = 1/2C2H4O2.Co/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2
| InChIKey = QAHREYKOYSIQPH-NUQVWONBAX
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2C2H4O2.Co/c2*1-2(3)4;/h2*1H3,(H,3,4);/q;;+2/p-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = QAHREYKOYSIQPH-UHFFFAOYSA-L
| CASNo = 71-48-7
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo_Comment = (anhydrous)
| CASNo2_Ref = {{cascite|correct|CAS}}
| CASNo2 = 6147-53-1
| CASNo2_Comment = (tetrahydrate)
| PubChem = 6277
| SMILES = [Co+2].[O-]C(=O)C.[O-]C(=O)C
| SMILES_Comment = ionic form
| SMILES1 = O=C(C)O[Co]OC(C)=O
| SMILES1_Comment = coordination form (anhydrate)
| SMILES2 = O=C(C)O[Co-4]([O+H2])([O+H2])([O+H2])([O+H2])OC(C)=O
| SMILES2_Comment = coordination form (tetrahydrate)
}}
|Section2={{Chembox Properties
| Formula = Co(C2H3O2)2
| Appearance = Pink crystals (anhydrous)
intense red crystals (tetrahydrate)
| Odor = vinegar (tetrahydrate)
| Density = 1.705 g/cm3 (tetrahydrate)
| MolarMass = 177.02124 g/mol (anhydrous)
249.08 g/mol (tetrahydrate)
| MeltingPtC = 140
| MeltingPt_notes = (tetrahydrate)
| BoilingPt =
| Solubility = Soluble
| SolubleOther = soluble in alcohol, dilute acids, pentyl acetate (tetrahydrate)
| RefractIndex = 1.542 (tetrahydrate)
| MagSus = +11,000·10−6 cm3/mol
}}
|Section3={{Chembox Hazards
| ExternalSDS = [http://hazard.com/msds/mf/baker/baker/files/c4895.htm J.T. Baker MSDS]
| NFPA-H = 1
| NFPA-R = 0
| NFPA-F = 0
| FlashPt =
| AutoignitionPt =
| LD50 = 503 mg/kg (oral, rat)
}}
}}
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.
Synthesis and structure
Like many other transition metal acetates, cobalt(II) acetate forms by the reaction of cobalt oxide or hydroxide and acetic acid:
: CoO + 2{{nbsp}}CH3CO2H + 3{{nbsp}}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.{{cite journal |doi=10.1107/S1600536803019093|title=Cobalt diacetate tetrahydrate|year=2003|last1=Sobolev|first1=Alexandre N.|last2=Miminoshvili|first2=Elguja B.|last3=Miminoshvili|first3=Ketevan E.|last4=Sakvarelidze|first4=Tamara N.|journal=Acta Crystallographica Section E|volume=59|issue=10|pages=m836–m837}} The analogous nickel acetate is isostructural.{{cite journal | doi = 10.1107/S0365110X5300171X | journal = Acta Crystallogr. | title = The crystal structures of nickel acetate, Ni(CH3COO)2·4H2O, and cobalt acetate, Co(CH3COO)2·4H2O | year = 1953 | last1 = Van Niekerk | first1 = J. N. | last2 = Schoening | first2 = F. R. L. | volume = 6 | issue = 7 | pages = 609–612}}
Various hydrates are known including Co(CH3CO2)2·H2O and [Co(CH3CO2)2]5·0.5 H2O.{{cite journal |doi=10.1002/zaac.200900457|title=Infinite Coordination Polymers of One- and Two-dimensional Cobalt Acetates|year=2010|last1=Zhang|first1=Gao|last2=Lin|first2=Jian|last3=Guo|first3=Dong-Wei|last4=Yao|first4=Shi-Yan|last5=Tian|first5=Yun-Qi|journal=Zeitschrift für Anorganische und Allgemeine Chemie|volume=636|issue=7|pages=1401–1404}}
Reactions and uses
Cobalt acetate is a precursor to various oil drying agents, catalysts that allow paints and varnishes to harden.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}}
Anhydrous cobalt acetate is a widely used source of cobalt in the synthesis of materials,{{cite journal |doi=10.1038/nmat4113|title=Metal–organic framework nanosheets in polymer composite materials for gas separation|year=2015|last1=Rodenas|first1=Tania|last2=Luz|first2=Ignacio|last3=Prieto|first3=Gonzalo|last4=Seoane|first4=Beatriz|last5=Miro|first5=Hozanna|last6=Corma|first6=Avelino|last7=Kapteijn|first7=Freek|last8=Llabrés i Xamena|first8=Francesc X.|last9=Gascon|first9=Jorge|journal=Nature Materials|volume=14|issue=1|pages=48–55|pmid=25362353|pmc=4270742|bibcode=2015NatMa..14...48R}} catalyst,{{cite journal |doi=10.1016/j.tet.2006.06.065|title=Recent advances in homogeneous transition metal-catalyzed aerobic alcohol oxidations|year=2006|last1=Schultz|first1=Mitchell J.|last2=Sigman|first2=Matthew S.|journal=Tetrahedron|volume=62|issue=35|pages=8227–8241}} and complexes.{{cite journal | doi = 10.1021/ed054p443 | journal = J. Chem. Educ. | title = Oxygen Uptake by a Cobalt(II) Complex | author = Appleton, T. G. | year = 1977 | volume = 54 | issue = 7 | pages = 443}}
Oxidation of acetic acid solutions of cobalt(II) acetate, e.g. with ozone, gives cobalt(III) acetates, which are strong oxidants.{{cite book |doi=10.1002/047084289X.rc188 |chapter=Cobalt(III) Acetate |title=Encyclopedia of Reagents for Organic Synthesis |date=2001 |last1=Periasamy |first1=Mariappan |last2=Radhakrishnan |first2=Ukkiramapandian |isbn=0-471-93623-5 }}
Safety
Cobalt salts are poisonous.{{citation needed|date=August 2024}}