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Copper(II) hydroxide
Encyclopedia
Copper 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.
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.
It was produced on an industrial scale during the 17th and 18th centuries for use in pigments such as blue verditer and Bremen green. These pigments were used in ceramics
and painting
.
, 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.
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."
This is the patina
that forms on bronze
and other copper alloy
statues such as the Statue of Liberty
.
. When it is dry, however, copper(II) hydroxide does not decompose unless it is heated to 185 °C.
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
.
Since copper(II) hydroxide is mildly amphoteric
, it dissolves slightly in concentrated alkali
, forming [Cu(OH)4]2-.
. 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
amine
s. 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 hydrazide
s 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:
, 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.
Hydroxide
Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and a hydrogen atom held together by a covalent bond, and carrying a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, as a ligand, a nucleophile, and a...
of the metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
copper
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
with the chemical formula
Chemical formula
A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....
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
Copper(II) carbonate
Copper carbonate is a blue-green compound forming part of the verdigris patina that is found on weathered brass, bronze, and copper. The colour can vary from bright blue to green, because there may be a mixture of both copper carbonate and basic copper carbonate in various stages of hydration...
and hydroxide. These are often greener in color.
History
Copper(II) hydroxide has been known since copper smelting began around 5000 BC although the alchemistsAlchemy
Alchemy is an influential philosophical tradition whose early practitioners’ claims to profound powers were known from antiquity. The defining objectives of alchemy are varied; these include the creation of the fabled philosopher's stone possessing powers including the capability of turning base...
were probably the first to manufacture it. This was easily done by mixing solutions of lye
Lye
Lye is a corrosive alkaline substance, commonly sodium hydroxide or historically potassium hydroxide . Previously, lye was among the many different alkalis leached from hardwood ashes...
(sodium or potassium hydroxide) and blue vitriol (copper(II) sulfate), 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. These pigments were used in ceramics
Ceramics (art)
In art history, ceramics and ceramic art mean art objects such as figures, tiles, and tableware made from clay and other raw materials by the process of pottery. Some ceramic products are regarded as fine art, while others are regarded as decorative, industrial or applied art objects, or as...
and painting
Painting
Painting is the practice of applying paint, pigment, color or other medium to a surface . The application of the medium is commonly applied to the base with a brush but other objects can be used. In art, the term painting describes both the act and the result of the action. However, painting is...
.
Natural occurrence
Copper(II) hydroxide is found in several different copper minerals, most notably azuriteAzurite
Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...
, malachite
Malachite
Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
, antlerite
Antlerite
Antlerite is a greenish hydrous copper sulfate mineral, with the formula Cu34. It occurs in tabular, acicular, or fibrous crystals with a vitreous luster...
, and brochantite
Brochantite
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is CuSO4·3Cu2. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it is named for its discoverer, the French geologist and mineralogist, A. J. M...
. Azurite
Azurite
Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...
(2CuCO3·Cu(OH)2
) and malachite
Malachite
Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
(CuCO3·Cu(OH)2) are carbonates while antlerite
Antlerite
Antlerite is a greenish hydrous copper sulfate mineral, with the formula Cu34. It occurs in tabular, acicular, or fibrous crystals with a vitreous luster...
(CuSO4·2Cu(OH)2) and brochantite
Brochantite
Brochantite is a sulfate mineral, one of a number of cupric sulfates. Its chemical formula is CuSO4·3Cu2. Formed in arid climates or in rapidly oxidizing copper sulfide deposits, it is named for its discoverer, the French geologist and mineralogist, A. J. M...
(CuSO4·3Cu(OH)2) are sulfates. Copper(II) hydroxide is rarely found as an uncombined mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
because it slowly reacts with carbon dioxide
Carbon dioxide
Carbon dioxide is a naturally occurring chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom...
from the atmosphere to form a basic copper(II) carbonate. The mineral of the formula Cu(OH)2 is called spertiniite.
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 hydroxide impurity. A purer product can be attained if ammonium chlorideAmmonium chloride
Ammonium chloride NH4Cl is an inorganic compound with the formula NH4Cl. It is a white crystalline salt that is highly soluble in water. Solutions of ammonium chloride are mildly acidic. Sal ammoniac is a name of natural, mineralogical form of 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
Electrolysis of water
Electrolysis of water is the decomposition of water into oxygen and hydrogen gas due to an electric current being passed through the water.-Principle:...
(containing a little electrolyte
Electrolyte
In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....
such as sodium bicarbonate
Sodium bicarbonate
Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula Na HCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder. It has a slightly salty, alkaline taste resembling that of washing soda . The natural mineral form is...
). A copper anode
Anode
An anode is an electrode through which electric current flows into a polarized electrical device. Mnemonic: ACID ....
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)
This is the patina
Patina
Patina is a tarnish that forms on the surface of bronze and similar metals ; a sheen on wooden furniture produced by age, wear, and polishing; or any such acquired change of a surface through age and exposure...
that forms on bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
and other copper alloy
Alloy
An alloy is a mixture or metallic solid solution composed of two or more elements. Complete solid solution alloys give single solid phase microstructure, while partial solutions give two or more phases that may or may not be homogeneous in distribution, depending on thermal history...
statues such as the Statue of Liberty
Statue of Liberty
The Statue of Liberty is a colossal neoclassical sculpture on Liberty Island in New York Harbor, designed by Frédéric Bartholdi and dedicated on October 28, 1886...
.
Reactions
Moist samples of copper(II) hydroxide slowly turn black due to the formation of copper(II) oxideCopper(II) oxide
Copper oxide or cupric oxide is the higher oxide of copper. As a mineral, it is known as tenorite.-Chemistry:It is a black solid with an ionic structure which melts above 1200 °C with some loss of oxygen...
. When it is dry, however, copper(II) hydroxide does not decompose unless it is heated to 185 °C.
Copper(II) hydroxide reacts with a solution of ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
to form a deep blue solution consisting of the [Cu(NH3)4]2+ complex ion
Complex (chemistry)
In chemistry, a coordination complex or metal complex, is an atom or ion , bonded to a surrounding array of molecules or anions, that are in turn known as ligands or complexing agents...
. Copper(II) hydroxide in ammonia solution, known as Schweizer's reagent
Schweizer's reagent
Schweizer's reagent is the chemical complex tetraamminediaquacopper dihydroxide, [Cu42]2. It is prepared by precipitating copper hydroxide from an aqueous solution of copper sulfate using sodium hydroxide or ammonia, then dissolving the precipitate in a solution of ammonia.When the entire amount of...
, possesses the interesting ability to dissolve cellulose
Cellulose
Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to over ten thousand β linked D-glucose units....
. This property led to it being used in the production of rayon
Rayon
Rayon is a manufactured regenerated cellulose fiber. Because it is produced from naturally occurring polymers, it is neither a truly synthetic fiber nor a natural fiber; it is a semi-synthetic or artificial fiber. Rayon is known by the names viscose rayon and art silk in the textile industry...
, a cellulose fiber
Cellulose fiber
Cellulose fibers are fibres of cellulose from any source, either natural or manufactured.-Textile:In the textile industry regenerated cellulose is used as fibers such as rayon, . Cellulose fibers are manufactured from dissolving pulp...
.
Since copper(II) hydroxide is mildly amphoteric
Amphoterism
In chemistry, an amphoteric species is a molecule or ion that can react as an acid as well as a base. The word is derived from the Greek word amphoteroi meaning "both"...
, it dissolves slightly in concentrated alkali
Alkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
, forming [Cu(OH)4]2-.
Reagent for organic chemistry
Copper(II) hydroxide has a rather specialized role in organic synthesisOrganic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
. Often, when it is utilized for this purpose, it is prepared in situ by mixing a soluble copper(II) salt and potassium hydroxide
Potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula KOH, commonly called caustic potash.Along with sodium hydroxide , this colorless solid is a prototypical strong base. It has many industrial and niche applications. Most applications exploit its reactivity toward acids and its corrosive...
.
It is sometimes used in the synthesis of aryl
Aryl
In the context of organic molecules, aryl refers to any functional group or substituent derived from an aromatic ring, be it phenyl, naphthyl, thienyl, indolyl, etc....
amine
Amine
Amines are organic compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are derivatives of ammonia, wherein one or more hydrogen atoms have been replaced by a substituent such as an alkyl or aryl group. Important amines include amino acids, biogenic amines,...
s. 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:
2.png)
Copper(II) hydroxide also converts acid hydrazide
Hydrazide
Hydrazides in organic chemistry are a class of organic compounds sharing a common functional group characterized by a nitrogen to nitrogen covalent bond with 4 substituents with at least one of them being an acyl group. The general structure for an hydrazide is R2-N-N-R3R4. A related class of...
s 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
Benzoic acid
Benzoic acid , C7H6O2 , is a colorless crystalline solid and the simplest aromatic carboxylic acid. The name derived from gum benzoin, which was for a long time the only source for benzoic acid. Its salts are used as a food preservative and benzoic acid is an important precursor for the synthesis...
and octanoic acid:
2_carboxylicacidcatalyst.png)
Uses
Copper(II) hydroxide has been used as an alternative to the Bordeaux mixtureBordeaux mixture
Bordeaux mixture is a mixture of copper sulfate and slaked lime used as a fungicide in vineyards. It is used mainly to control garden, vineyard, nursery and farm infestations of fungi, primarily downy mildew which can result from infections of Plasmopara viticola. It was invented in the Bordeaux...
, a fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
and nematicide
Nematicide
A nematicide is a type of chemical pesticide used to kill parasitic nematodes.One common nematicide is obtained from neem cake, the residue obtained after cold-pressing the fruit and kernels of the neem tree. Known by several names in the world, the tree was first cultivated in India in ancient...
. Such products include Dupont's Kocide 3000. Copper(II) hydroxide is also occasionally used as ceramic colorant
Ceramic colorants
'Ceramic colorants' are added to a glaze or a clay to create color. Carbonates and oxides of certain metals, characterize most colorants including the commonly used cobalt carbonate, cobalt oxide, chrome oxide, red iron oxide, and copper carbonate...
.
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.