Copper(II) oxalate

Copper(II) oxalate

Names
Other names Copper (II) oxalate, cupric oxalate, copper(2+) ethanedioate
Identifiers
CAS Number	814-91-5^Y hemihydrate: 55671-32-4
3D model (JSmol)	Interactive image
ChemSpider	12596
ECHA InfoCard	100.011.283
EC Number	212-411-4
PubChem CID	54602330
UNII	BN136S94FS^N
UN number	3077
CompTox Dashboard (EPA)	DTXSID0041802
InChI Key: QYCVHILLJSYYBD-UHFFFAOYSA-N InChI=1S/C2H2O4.Cu/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2
SMILES O=C([O-])C([O-])=O.[Cu+2]
Properties
Chemical formula	CuC 2O 4
Molar mass	151.56
Appearance	blue solid
Density	6.57 g/cm^3
Solubility in water	insoluble
Solubility product (Ksp)	4.43×10^−10[1]
Hazards
GHS labelling:
Pictograms	[2]
Signal word	Warning
Hazard statements	H302, H302+H312, H312
Precautionary statements	P264, P270, P280, P301+P312, P302+P352, P312, P322, P330, P363, P501
Related compounds
Related compounds	Calcium oxalate Sodium oxalate Magnesium oxalate Strontium oxalate Barium oxalate Iron(II) oxalate Iron(III) oxalate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Copper(II) oxalate are inorganic compounds with the chemical formula CuC₂O₄(H₂O)_x. The value of x can be 0, 0.44, and 1. Two of these species are found as secondary minerals (degradation of minerals), whewellite (monohydrate) and moolooite (0.44 hydrate).[3] The anhydrous compound has been characterized by X-ray crystallography.[4] Many transition metal oxalate complexes are known.

Copper(II) monooxalates are practically insoluble in all solvents. They are coordination polymers.[5]

Synthesis

Copper(II) oxalate can be produced by precipitation from acidified aqueous copper(II) salts and oxalic acid.[6][7]

CuSO₄ + H₂C₂O₄ + H₂O → CuC₂O₄·H₂O + H₂SO₄

Reactions

Upon heating to 130 °C, the hydrated copper(II) oxalates convert to the anhydrous cupric oxalate. Further heating at higher temperatures under an atmosphere of hydrogen gives copper metal, suitable as a reagent.[6]

The hydrates bind Lewis bases.

Hydrated copper(II) oxalate reacts with alkali metal oxalates and ammonium oxalate to give bis(oxalato)cuprate:[8]

CuC₂O₄)(H₂O)_x + C₂O2−4 → [Cu(C₂O₄)₂]^2− + x H₂O

Uses

Copper oxalate is used as a catalyst for organic reactions, as a stabilizer for acetylated polyformaldehyde.[9][10]

Related compounds

• Cuprous oxalates.[11]

References

1. John Rumble (June 18, 2018). CRC Handbook of Chemistry and Physics (99 ed.). CRC Press. pp. 5–188. ISBN 978-1138561632.
2. "Copper oxalate - Substance Information - ECHA". European Chemical Agency. Retrieved 17 June 2021.
3. Christensen, Axel Nørlund; Lebech, Bente; Andersen, Niels Hessel; Grivel, Jean-Claude (2014). "The Crystal structure of paramagnetic copper(<SCP>ii</SCP>) oxalate (CuC₂O₄): Formation and thermal decomposition of randomly stacked anisotropic nano-sized crystallites" (PDF). Dalton Trans. 43 (44): 16754–16768. doi:10.1039/C4DT01689K. PMID 25278188.
4. Schmittler, H. (1968). "Zum Strukturprinzip des fehlgeordneten Kupfer(II)-Oxalats CuC₂O₄·nH₂O". Monatsberichte der Deutschen Akademie der Wissenschaften zu Berlin. 10: 581-604.
5. "Hazardous Substances Data Bank (HSDB) : 265". National Library of Medicine. Retrieved 17 June 2021.
6. O. Glemser; R. Sauer (1963). "Copper(II) Sulfide". In G. Brauer (ed.). Handbook of Preparative Inorganic Chemistry, 2nd Ed. Vol. 2pages=1017-1018. NY,NY: Academic Press.
7. Gooch, Frank Austin (1909). The precipitation of copper oxalate in analysis. p. 448. OCLC 890741677.
8. Kirschner, Stanley; McLean, John A.; Meerman, Gerardine (1960). "Potassium Dioxalatocuprate(II) 2-Hydrate". Inorganic Syntheses. Vol. 6. pp. 1–2. doi:10.1002/9780470132371.ch1. ISBN 978-0-470-13165-7.
9. Richardson, H. Wayne (1997). Handbook of Copper Compounds and Applications. CRC Press. p. 84. ISBN 978-0-8247-8998-5.
10. Richardson, H. Wayne (2000). "Copper Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a07_567. ISBN 978-3-527-30385-4.
11. Royappa, A. Timothy; Royappa, Andrew D.; Moral, Raphael F.; Rheingold, Arnold L.; Papoular, Robert J.; Blum, Deke M.; Duong, Tien Q.; Stepherson, Jacob R.; Vu, Oliver D.; Chen, Banghao; Suchomel, Matthew R.; Golen, James A.; André, Gilles; Kourkoumelis, Nikolaos; Mercer, Andrew D.; Pekarek, Allegra M.; Kelly, Dylan C. (November 2016). "Copper(I) oxalate complexes: Synthesis, structures and surprises". Polyhedron. 119: 563–574. doi:10.1016/j.poly.2016.09.043.