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Copper II hydroxide
Identifiers
CAS number 20427-59-2 Yes check.svgY
PubChem 164826
ChemSpider 144498
SMILES
InChI
InChI key JJLJMEJHUUYSSY-NUQVWONBAH
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 [1]
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
NFPA 704.svg
0
2
0
Flash point Non-flammable
LD50 1000 mg/kg (oral, rat)
Related compounds
Other anions Copper(II) oxide
Copper(II) carbonate
Copper(II) sulfate
Copper(II) chloride
Other cations Nickel(II) hydroxide
Zinc hydroxide
Iron(II) hydroxide
Cobalt hydroxide
Related compounds Copper(I) oxide
Copper(I) chloride
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Copper(II) hydroxide (chemical formula Cu(OH)2) is the hydroxide of the metal copper. 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.

Contents

History

Copper(II) hydroxide has been known since copper smelting began around 5000 BCE although the alchemists were probably the first to manufacture it.[2] This was easily done by mixing solutions of lye and blue vitriol, both chemicals which were known in antiquity.

It was produced on an industrial scale during the 17th and 18th centuries for use in pigments such as blue verditer and Bremen green.[3] These pigments were used in ceramics and painting.[4]

Chemical Properties

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Synthesis

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 hydroxid] 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 and operating processes in order to eliminate impurities lead to the destruction of the hydroxide, giving rise to the oxide CuO, more stable [5]. 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."[6]

2Cu(s) + H2O(g) + CO2(g) + O2(g) ---> Cu(OH)2(s) + CuCO3(s)

This is the patina that forms on bronze and other copper alloy statues such as the Statue of Liberty.

Reactions

Moist samples of copper(II) hydroxide slowly turn black due to the formation of copper(II) oxide.[7] When it is dry, however, copper(II) hydroxide does not decompose unless it is heated to 185°C.[8]

Copper(II) hydroxide reacts with a solution of ammonia to form a deep blue solution consisting of the [Cu(NH3)4]2+ complex ion, but the hydroxide is reformed when the solution is diluted with water. 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.

Since copper(II) hydroxide is mildly amphoteric, it dissolves slightly in concentrated alkali, forming [Cu(OH)4]2-.[9]

Use as an organic reagent

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.

UllmannCu(OH)2.PNG

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.

Cu(OH)2 CarboxylicAcidCatalyst.PNG

Natural occurrence

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.

Uses

Copper(II) hydroxide has been used as an alternative to the Bordeaux mixture, a fungicide and nematacide.[10] 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 is sold under the name Spin Out, which was first introduced by Griffin L.L.C. The rights are now owned by SePRO Corp.[11]

Precautions

Copper(II) hydroxide is a skin, eye and respiratory irritant. Always wear safety glasses when handling copper hydroxide. In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.

References

  1. Roscoe, H. E., & Schorlemmer, C. (1879). A Treatise on Chemistry 2nd Ed, Vol 2, Part 2. MacMillan & Co. (p 498).
  2. Paquette, Leo A. (1995). Encyclopedia of Reagents for Organic Synthesis, 8 Volume Set. Wiley. ISBN 0-4719-3623-5.

Footnotes

  1. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0070494398
  2. ^ Richard Cowen, Essays on Geology, History, and People, Chapter 3: "Fire and Metals: Copper".
  3. ^ Tony Johansen, Historic Artist's Pigments. PaintMaking.com. 2006.
  4. ^ Blue verditer. Natural Pigments. 2007.
  5. ^ 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. 
  6. ^ Masterson, W. L., & Hurley, C. N. (2004). Chemistry: Principles and Reactions, 5th Ed. Thomson Learning, Inc. (p 331)"
  7. ^ Watts, Henry (1872). A Dictionary of Chemistry and the Allied Branches of Other Sciences, Vol 2. Longmans, Green, and Co. (p 69).
  8. ^ Copper (II) hydroxide. Ceramic Materials Database. 2003.
  9. ^ Pauling, Linus (1970). General Chemistry. Dover Publications, Inc. (p 702).
  10. ^ Bordeaux Mixture. UC IPM online. 2007.
  11. ^ "SePRO Corporation".

External links


Simple English

File:Copper(II)
Copper(II) hydroxide

Copper(II) hydroxide, also known as cupric hydroxide, is a chemical compound. Its chemical formula is Cu(OH)2. It contains copper in its +2 oxidation state. It also contains hydroxide ions.

Contents

Properties

A picture of copper(II) hydroxide reacting with ammonia. Some copper(II) hydroxide is on the bottom of the test tube.

Copper(II) hydroxide is light blue. It is rubbery when wet. When it is mixed with copper(II) carbonate, it is greenish. It reacts with carbon dioxide to make copper(II) carbonate when in air. It turns into copper(II) oxide when wet. When it is dry, though, it only turns into copper(II) oxide when it is heated. It reacts with ammonia to make a very dark blue solution.

Preparation

Copper(II) hydroxide can be made by reacting copper sulfate with sodium hydroxide. Potassium hydroxide can be used, but it is more expensive. It can also be made by electrolyzing a solution of sodium bicarbonate with a copper anode.

Uses

Copper(II) hydroxide is used to kill mold in paints. It can be used to color ceramics. It can be used as a catalyst.

Safety

It is not toxic in small amounts, but it can dissolve in stomach acid to make soluble copper, which can poison much more easily.

See also


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