Copper(II) acetate, also referred to as cupric acetate, is the
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
with the
formula
In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwe ...
where is
acetate
An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic, or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...
(). The hydrated derivative, , which contains one molecule of water for each copper atom, is available commercially.
Anhydrous copper(II) acetate is a dark green
crystalline solid, whereas is more bluish-green. Since ancient times, copper acetates of some form have been used as
fungicide
Fungicides are pesticides used to kill parasitic fungi or their spores. Fungi can cause serious damage in agriculture, resulting in losses of yield and quality. Fungicides are used both in agriculture and to fight fungal infections in animals, ...
s and green
pigment
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
s. Today, copper acetates are used as
reagents for the synthesis of various inorganic and
organic compounds
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
.
Copper acetate, like all copper compounds, emits a blue-green glow in a
flame.
Structure
Copper acetate hydrate adopts the
paddle wheel structure seen also for related Rh(II) and Cr(II) tetraacetates. One oxygen atom on each acetate is bound to one copper atom at . Completing the
coordination sphere are two water
ligand
In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's el ...
s, with distances of . The two copper atoms are separated by only , which is close to the separation in metallic copper. The two copper centers interact resulting in a diminishing of the magnetic moment such that at temperatures below , is essentially diamagnetic. was a critical step in the development of modern theories for
antiferromagnetic exchange coupling, which ascribe its low-temperature diamagnetic behavior to cancellation of the two opposing spins on the adjacent copper atoms.
Synthesis
Copper(II) acetate is prepared industrially by heating
copper(II) hydroxide or
basic copper(II) carbonate with
acetic acid
Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
.
[
]
Uses in chemical synthesis
Copper(II) acetate has found some use as an oxidizing agent in organic syntheses. In the Eglinton reaction is used to couple terminal alkynes to give a 1,3- diyne:
:
The reaction proceeds via the intermediacy of copper(I) acetylides, 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 Cu2(OAc)4. It has been used for hydroamination of acrylonitrile.
In chemical analysis, it serves as an oxidizing agent in both the Barfoed's test for presence of monosaccharides and as a precursor to a copper-fatty acid complex in the colorimetric copper soap assay to test for free fatty acids.
It reacts with arsenic trioxide to form copper acetoarsenite, a powerful insecticide
Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...
and fungicide called Paris green.
Related compounds
Heating a mixture of anhydrous copper(II) acetate and copper metal affords copper(I) acetate:
:
Unlike the copper(II) derivative, copper(I) acetate is colourless and diamagnetic.
"Basic copper acetate" is prepared by neutralizing an aqueous solution of copper(II) acetate. The basic acetate is poorly soluble. This material is a component of verdigris
Verdigris () is a common name for any of a variety of somewhat toxic copper salt (chemistry), salts of acetic acid, which range in colour from green to a blue-green, bluish-green depending on their chemical composition.H. Kühn, Verdigris and Cop ...
, the blue-green substance that forms on copper during long exposures to atmosphere.
Other uses
A mixture of copper acetate and ammonium chloride is used to chemically color copper with a bronze patina.
Mineralogy
The mineral hoganite is a naturally occurring form of copper(II) acetate.
References
External links
Copper.org – Other Copper Compounds
5 Feb. 2006
6 Feb. 2006
6 Feb. 2006
Australian - National Pollutant Inventory
8 Aug. 2016
USA NIH National Center for Biotechnology Information
8 Aug. 2016
{{Acetates
Copper(II) compounds
Acetates
Oxidizing agents
Catalysts