- Copper(II) hydroxide
Copper(II) hydroxide Identifiers CAS number PubChem ChemSpider KEGG Jmol-3D images Image 1 Properties Molecular formula Cu(OH)2 Molar mass 97.561 g/mol Appearance Blue or blue-green solid Density 3.368 g/cm3, solid Melting point
80 °C (decomp into CuO)
Solubility in water negligible Solubility product, Ksp 2.20 x 10-20 Solubility insoluble in ethanol;
soluble in NH4OH, KCN
Hazards MSDS http://www.sciencelab.com/xMSDS-Cupric_Hydroxide-9923594 EU Index Not listed Main hazards Skin, Eye, & Respiratory Irritant NFPA 704 Flash point Non-flammable LD50 1000 mg/kg (oral, rat) Related compounds Other anions Copper(II) oxide
Other cations Nickel(II) hydroxide
Related compounds Copper(I) oxide
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Copper(II) hydroxide is the hydroxide of the metal copper with the chemical formula of Cu(OH)2. Copper hydroxide is a pale blue, gelatinous solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper hydroxide, quite likely a mixture of copper(II) carbonate and hydroxide. These are often greener in color.
Copper(II) hydroxide has been known since copper smelting began around 5000 BC although the alchemists were probably the first to manufacture it. This was easily done by mixing solutions of lye (sodium or potassium hydroxide) and blue vitriol (copper(II) sulfate), both chemicals which were known in antiquity.
Copper(II) hydroxide is found in several different copper minerals, most notably azurite, malachite, antlerite, and brochantite. Azurite (2CuCO3·Cu(OH)2 ) and malachite (CuCO3·Cu(OH)2) are carbonates while antlerite (CuSO4·2Cu(OH)2) and brochantite (CuSO4·3Cu(OH)2) are sulfates. Copper(II) hydroxide is rarely found as an uncombined mineral because it slowly reacts with carbon dioxide from the atmosphere to form a basic copper(II) carbonate. The mineral of the formula Cu(OH)2 is called spertiniite.
Copper(II) hydroxide can be produced by adding a small amount of sodium hydroxide to a dilute solution of copper(II) sulfate (CuSO4 · 5H2O). The precipitate produced in this manner, however, often contains water molecules and an appreciable amount of sodium hydroxide impurity. A purer product can be attained if ammonium chloride is added to the solution beforehand. Nevertheless, it is impossible to obtain a pure product; processes for eliminating impurities lead to the destruction of the hydroxide, giving rise to the more stable oxide, CuO. Alternatively, copper hydroxide is readily made by electrolysis of water (containing a little electrolyte such as sodium bicarbonate). A copper anode is used, often made from scrap copper.
"Copper in moist air slowly acquires a dull green coating. The green material is a 1:1 mole mixture of Cu(OH)2 and CuCO3."
- 2 Cu (s) + H2O (g) + CO2 (g) + O2 (g) → Cu(OH)2 (s) + CuCO3 (s)
Copper(II) hydroxide reacts with a solution of ammonia to form a deep blue solution consisting of the [Cu(NH3)4]2+ complex ion. Copper(II) hydroxide in ammonia solution, known as Schweizer's reagent, possesses the interesting ability to dissolve cellulose. This property led to it being used in the production of rayon, a cellulose fiber.
Reagent for organic chemistry
Copper(II) hydroxide has a rather specialized role in organic synthesis. Often, when it is utilized for this purpose, it is prepared in situ by mixing a soluble copper(II) salt and potassium hydroxide.
It is sometimes used in the synthesis of aryl amines. For example, copper(II) hydroxide catalyzes the reaction of ethylenediamine with 1-bromoanthraquinone or 1-amino-4-bromoanthraquinone to form 1-((2-aminoethyl)amino)anthraquinone or 1-amino-4-((2-aminoethyl)amino)anthraquinone, respectively:
Copper(II) hydroxide also converts acid hydrazides to carboxylic acids at room temperature. This is especially useful in synthesizing carboxylic acids with other fragile functional groups. The published yields are generally excellent as is the case with the production of benzoic acid and octanoic acid:
Copper(II) hydroxide has been used as an alternative to the Bordeaux mixture, a fungicide and nematicide. Such products include Dupont's Kocide 3000. Copper(II) hydroxide is also occasionally used as ceramic colorant.
Copper(II) hydroxide has been combined with latex paint, making a product designed to control root growth in potted plants. Secondary and lateral roots thrive and expand, resulting in a dense and healthy root system. It was sold under the name Spin Out, which was first introduced by Griffin L.L.C. The rights are now owned by SePRO Corp. It is now sold as Microkote either in a solution you apply yourself, or as treated pots.
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- Paquette, Leo A. (1995). Encyclopedia of Reagents for Organic Synthesis, 8 Volume Set. Wiley. ISBN 0-471-93623-5.
- ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
- ^ Richard Cowen, Essays on Geology, History, and People, Chapter 3: "Fire and Metals: Copper".
- ^ Tony Johansen, Historic Artist's Pigments. PaintMaking.com. 2006.
- ^ Blue verditer. Natural Pigments. 2007.
- ^ Y. Cudennec, A. Lecerf (2003). "The transformation of Cu(OH)2 into CuO, revisited". Solid State Sciences 5: 1471–1474. doi:10.1016/j.solidstatesciences.2003.09.009.
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- ^ Copper (II) hydroxide. Ceramic Materials Database. 2003.
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- ^ Bordeaux Mixture. UC IPM online. 2007.
- ^ "SePRO Corporation".
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