Copper(II) acetate 2987828 223645608 2008-07-05T01:42:48Z Rifleman 82 1255637 /* History */ fix link {{Chembox new | Name = Copper(II) acetate | ImageFile = Copper(II)-acetate.jpg <!-- | ImageSize = 200px --> | ImageName = Copper(II) acetate hydrate | IUPACName = Copper(II) acetate | OtherNames = Cupric acetate | Section1 = {{Chembox Identifiers | CASOther = 142-71-2 (anhydrous)</br>6046-93-1 (monohydrate) }} | Section2 = {{Chembox Properties | Formula = Cu<sub></sub>(CH<sub>3</sub>COO)<sub>2</sub> | MolarMass = 182 g/mol | Appearance = Dark green crystalline solid | MeltingPt = 115 °C (388 K) | BoilingPt = 240 °C (513 K) | Solvent = other solvents | SolubleOther = 7.2 g/100 mL cold water</br>20 g / 100 mL hot water</br>Soluble in alcohol</br>Slightly soluble in ether and glycerol | Density = 1.88 g/mL }} | Section3 = {{Chembox Structure | CrystalStruct = [[Monoclinic]] }} | Section7 = {{Chembox Hazards | ExternalMSDS = [http://www.jtbaker.com/msds/englishhtml/c5808.htm Baker MSDS] | NFPA-H = 2 | NFPA-F = | NFPA-R = | FlashPt = Non-flammable | RPhrases = 22-36/37/38-50/53 | SPhrases = 26-60-61 }} }} '''Copper(II) acetate''', also referred to as '''cupric acetate''', is the [[chemical compound]] with the [[chemical formula|formula]] [[Cu]]<sub></sub>(OAc)<sub>2</sub> where AcO<sup>-</sup> is [[acetate]] (CH<sub>3</sub>CO<sub>2</sub><sup>-</sup>). The [[hydrated]] derivative, which contains one molecule of water for each Cu atom, is available commercially. Cu<sub></sub>(OAc)<sub>2</sub> is a dark green [[crystalline]] solid, whereas Cu<sub></sub>(OAc)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub> is more bluish-green. Since ancient times, copper acetates of some form have been used as [[fungicide]]s and green [[pigment]]s. Today, Cu<sub></sub>(OAc)<sub>2</sub> is used as a source of copper(II) in inorganic synthesis and as a [[catalyst]] or an [[oxidizing agent]] in [[organic synthesis]]. Copper acetate, like all copper compounds, emits a blue-green glow in a flame. ==History== Copper(II) acetate is the primary component of [[verdigris]],{{Fact|date=June 2007}} the blue-green substance that forms on copper during long exposures to atmosphere. It was historically prepared in vineyards, since [[acetic acid]] is a byproduct of [[Fermentation (food)|fermentation]]. Copper sheets were alternately layered with fermented grape skins and [[dregs]] left over from wine production and exposed to air. This would leave a blue substance on the outside of the sheet. This was then scraped off and dissolved in water. The resulting solid was used as a pigment, or combined with [[arsenic trioxide]] to form copper acetoarsenite, a powerful [[insecticide]] and fungicide called [[Paris Green]] or Schweinfurt Green. Copper (cupric) acetate tablets were believed to repel sharks in the mid twentieth century. [[SCUBA]] divers strapped tablets of the compound to their belt and/or ankles to provide protection against sharks. It was used by [[Jacques-Yves Cousteau]] and his researchers with questionable results.<ref>{{cite book |last= Cousteau |first= Jacques-Yves |coauthors= [[Frédéric Dumas]] |title= [[The Silent World: A Story of Undersea Discovery and Adventure|The Silent World]] |publisher= [[Harper and Row, Publishers, Inc.]] |year= 1953 |isbn= 0-7922-6796-6 |authorlink = Jacques-Yves Cousteau |pages = 127-135 }}</ref> ==Uses in chemical synthesis== The uses for copper(II) acetate are more plentiful as a catalyst or [[oxidizing agent]] in organic syntheses. For example, Cu<sub>2</sub>(OAc)<sub>4</sub> is used to couple two terminal [[alkynes]] to make a 1,3-[[diyne]]:<ref>P. Vogel, J. Srogl "Copper(II) Acetate" in "EROS Encyclopedia of Reagents for Organic Synthesis" Copper(II) Acetate, 2005 John Wiley & Sons.</ref> :Cu<sub>2</sub>(OAc)<sub>4</sub> + 2 RC≡CH → 2 CuOAc + RC≡C-C≡CR + 2 HOAc The reaction proceeds via the intermediacy of [[copper(I) acetylide]]s, which are then oxidized by the copper(II) acetate, releasing the acetylide radical. A related reaction involving copper acetylides is the synthesis of [[ynamines]], terminal alkynes with amine groups using Cu<sub>2</sub>(OAc)<sub>4</sub>.<sup>[2]</sup> ==Structure== [[Image:Copper(II)-acetate-3D-balls.png|thumb|right|200px|The dinuclear structure of copper(II) acetate]] Cu<sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub> adopts the "Chinese lantern" structure seen also for related Rh(II) and Cr(II) tetraacetates.<ref>{{cite journal | author = van Niekerk, J. N. Schoening, F. R. L. | title = X-Ray Evidence for Metal-to-Metal Bonds in Cupric and Chromous Acetate | journal = [[Nature (journal)|Nature]] | year = 1953 | volume = 171 | pages = 36-37 | doi = 10.1038/171036a0}}</ref><ref>Wells, A.F. (1984). Structural Inorganic Chemistry, Oxford: Clarendon Press.</ref> One oxygen atom on each acetate is bound to one copper at 1.97 [[angstrom|Å]] (197 [[picometer|pm]]. Completing the [[coordination sphere]] are two water [[ligand]]s, with Cu-O distances of 2.20 Å (220 pm). The two five-coordinate copper atoms are separated by only 2.65 Å (265 pm), which is close to the Cu--Cu separation in metallic copper.<sup>[5]</sup>. The two copper centers interact resulting in a diminishing of the magnetic moment such that near 90 [[kelvin|K]], Cu<sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub> is essentially diamagnetic due to cancellation of the two opposing spins. Cu<sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub> was a critical step in the development of modern theories for [[antiferromagnetic]] coupling.<ref>R. L. Carlin "Magnetochemistry" Springer: Berlin, 1986</ref> ==Synthesis== Copper(II) acetate has been synthesized for centuries by the method described in the history section.<!--really?--> This method, however, leads to an impure copper(II) acetate. In a laboratory, a much purer form can be synthesized in a simple three-step procedure. The overall reaction is as follows:<sup>[6]</sup> :2 CuSO<sub>4</sub><sup>.</sup>5H<sub>2</sub>O + 4 NH<sub>3</sub> + 4 CH<sub>3</sub>COOH → Cu<sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub> + 2 [NH<sub>4</sub>]<sub>2</sub>[SO<sub>4</sub>] + 8 H<sub>2</sub>O The hydrate form can be dehydrated by heating at 100 °C in a vacuum:<ref>{{cite journal | author = S. J. Kirchner, Q. Fernando | title = Copper(I) Acetate | journal = [[Inorg. Synth.]] | year = 1980 | volume 20 | pages =53-55 | doi = 10.1002/9780470132517.ch16}}</ref> :Cu<sub>2</sub>(OAc)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub> → Cu<sub>2</sub>(OAc)<sub>4</sub> + 2 H<sub>2</sub>O Heating a mixture of anhydrous Cu<sub>2</sub>(OAc)<sub>4</sub> and copper metal affords colorless, volatile cuprous acetate:<ref>Parish, E. J.; Kizito, S. A. "Copper(I) Acetate" Encyclopedia of Reagents for Organic Synthesis, 2001 John Wiley & Sons. DOI: 10.1002/047084289X.rc193.</ref> :2 Cu + Cu<sub>2</sub>(OAc)<sub>4</sub> → 4 CuOAc ==References== <references/> ==External links== *[http://www.copper.org/applications/compounds/other_compounds.html Copper.org – Other Copper Compounds] 5 Feb. 2006 *[http://www.infoplease.com/ce6/sci/A0837650.html Infoplease.com -- Paris green] 6 Feb. 2006 *[http://webexhibits.org/pigments/indiv/overview/verdigris.html Verdigris – History and Synthesis] 6 Feb. 2006 *[http://www.npi.gov.au/database/substance-info/profiles/27.html National Pollutant Inventory - Copper and compounds fact sheet] *[http://www.nsc.org/ehc/chemical/cupric_a.htm National Safety Council Chemical Backgrounder] [[Category:Copper compounds]] [[Category:Acetates]] [[Category:Oxidizing agents]] [[Category:Catalysts]] [[ar:خلات نحاس ثنائي]] [[de:Kupferacetat]] [[fr:Acétate de cuivre]] [[id:Tembaga(II) asetat]] [[it:Acetato rameico monoidrato]] [[ja:酢酸銅(II)]] [[pl:Grynszpan]] [[pt:Acetato de cobre (II)]] [[qu:Siwayru]] [[zh:乙酸铜]]