Copper(II) hydroxide

Last updated
Copper(II) hydroxide
Rez(II)-hidroxid.jpg
Kristallstruktur Kupfer(II)-hydroxid.png
Names
IUPAC name
Copper(II) hydroxide
Other names
Cupric hydroxide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.039.817 OOjs UI icon edit-ltr-progressive.svg
KEGG
PubChem CID
UNII
  • InChI=1S/Cu.2H2O/h;2*1H2/q+2;;/p-2 Yes check.svgY
    Key: JJLJMEJHUUYSSY-UHFFFAOYSA-L Yes check.svgY
  • InChI=1/Cu.2H2O/h;2*1H2/q+2;;/p-2
    Key: JJLJMEJHUUYSSY-NUQVWONBAH
  • [Cu+2].[OH-].[OH-]
Properties
Cu(OH)2
Molar mass 97.561 g/mol
AppearanceBlue or blue-green solid
Density 3.368 g/cm3, solid
Melting point 80 °C (176 °F; 353 K) approximate, decomposes into CuO
negligible
2.20 x 10−20 [1]
Solubility insoluble in ethanol;
soluble in NH4OH
+1170.0·10−6 cm3/mol
Thermochemistry
Std molar
entropy
(S298)
108 J·mol−1·K−1
−450 kJ·mol−1
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Skin, Eye, & Respiratory Irritant
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
2
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
1000 mg/kg (oral, rat)
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 1 mg/m3 (as Cu) [2]
REL (Recommended)
TWA 1 mg/m3 (as Cu) [2]
IDLH (Immediate danger)
TWA 100 mg/m3 (as Cu) [2]
Safety data sheet (SDS) SDS
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
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Copper(II) hydroxide is the hydroxide of copper with the chemical formula of Cu(OH)2. It is a pale greenish blue or bluish green solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper(II) hydroxide, although they likely consist of a mixture of copper(II) carbonate and hydroxide. Cupric hydroxide is a strong base, although its low solubility in water makes this hard to observe directly. [3]

Contents

Occurrence

Copper(II) hydroxide has been known since copper smelting began around 5000 BC although the alchemists were probably the first to manufacture it by mixing solutions of lye (sodium or potassium hydroxide) and blue vitriol (copper(II) sulfate). [4] Sources of both compounds were available 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. [5] These pigments were used in ceramics and painting. [6]

Mineral

The mineral of the formula Cu(OH)2 is called spertiniite. 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. Thus copper(II) hydroxide slowly acquires a dull green coating in moist air by the reaction:

2 Cu(OH)2 + CO2 → Cu2CO3(OH)2 + H2O

The green material is in principle a 1:1 mole mixture of Cu(OH)2 and CuCO3. [7] This patina forms on bronze and other copper alloy statues such as the Statue of Liberty.

Production

Copper(II) hydroxide can be produced by adding sodium hydroxide to various copper(II) sources. The nature of the resulting copper(II) hydroxide however is sensitive to detailed conditions. Some methods produce granular, robust copper(II) hydroxide while other methods produce a thermally sensitive colloid-like product. [3]

Traditionally a solution of a soluble copper(II) salt, such as copper(II) sulfate (CuSO4·5H2O) is treated with base: [8]

2NaOH + CuSO4·5H2O → Cu(OH)2 + 6H2O + Na2SO4

This form of copper hydroxide tends to convert to black copper(II) oxide: [9]

Cu(OH)2 → CuO + H2O

A purer product can be attained if ammonium chloride is added to the solution beforehand to generate ammonia in situ. [10] Alternatively it can be produced in a two-step procedure from copper(II) sulfate via "basic copper sulfate:" [9]

4 CuSO4 + 6 NH3 + 6H2O → Cu4SO4(OH)6 + 3 (NH4)2SO4
Cu4SO4(OH)6 + 2 NaOH → 4 Cu(OH)2 + Na2SO4

Alternatively, copper hydroxide is readily made by electrolysis of water (containing a little electrolyte such as sodium sulfate or magnesium sulfate) with a copper anode:

Cu + 2OH → Cu(OH)2 + 2e

Structure

The structure of Cu(OH)2 has been determined by X-ray crystallography. The copper center is square pyramidal. Four Cu-O distances in the plane range are 1.96 Å, and the axial Cu-O distance is 2.36 Å. The hydroxide ligands in the plane are either doubly bridging or triply bridging. [11]

Reactions

It is stable to about 100 °C. [8] Above this temperature, it will decompose into copper(II) oxide.

Copper(II) hydroxide reacts with a solution of ammonia to form a deep blue solution of tetramminecopper [Cu(NH3)4]2+ complex ion.

Copper(II) hydroxide oxidizes of ammonia in presence of oxygen, giving rise to copper ammine nitrites, such as Cu(NO2)2(NH3)n. [12] [13]

Copper(II) hydroxide is mildly amphoteric. It dissolves slightly in concentrated alkali, forming [Cu(OH)4]2−. [14] [8]

Reagent for organic chemistry

Copper(II) hydroxide has a only 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: [15]

Ullmann redrawn.tif

Copper(II) hydroxide also converts acid hydrazides to carboxylic acids at room temperature. This conversion can be used in the synthesis of carboxylic acids in the presence of other fragile functional groups. The yields are generally excellent as is the case with the production of benzoic acid and octanoic acid: [15]

Carboxylic acid synthesis .tif

Uses

Copper(II) hydroxide in ammonia solution, known as Schweizer's reagent, dissolves cellulose. [3] This property led to it being used in the production of rayon, a cellulose fiber.

It is also used in the aquarium industry for its ability to destroy external parasites in fish, including flukes, marine ich, Brooklynellosis, and marine velvet, without killing the fish. Although other water-soluble copper compounds can be effective in this role, they generally result in high fish mortality.

Copper(II) hydroxide has been used as an alternative to the Bordeaux mixture, a fungicide and nematicide. [3] [16] Such products include Kocide 3000, produced by Kocide L.L.C. 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. [17] It is now sold as Microkote either in a solution applied by the end user, or as treated pots.

Other copper(II) hydroxides

Chemical structure of azurite, one of many copper(II) hydroxides (color code: red = O, green = Cu, gray = C, white = H). Azurite crystal structure.jpg
Chemical structure of azurite, one of many copper(II) hydroxides (color code: red = O, green = Cu, gray = C, white = H).

Together with other components, copper(II) hydroxides are numerous. Several copper(II)-containing minerals contain hydroxide. Notable examples include azurite, malachite, antlerite, and brochantite. Azurite (2CuCO3·Cu(OH)2) and malachite (CuCO3·Cu(OH)2) are hydroxy-carbonates, whereas antlerite (CuSO4·2Cu(OH)2) and brochantite (CuSO4·3Cu(OH)2) are hydroxy-sulfates.

Many synthetic copper(II) hydroxide derivatives have been investigated. [19]

Related Research Articles

<span class="mw-page-title-main">Hydroxide</span> Chemical compound

Hydroxide is a diatomic anion with chemical formula OH. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It functions as a base, a ligand, a nucleophile, and a catalyst. The hydroxide ion forms salts, some of which dissociate in aqueous solution, liberating solvated hydroxide ions. Sodium hydroxide is a multi-million-ton per annum commodity chemical. The corresponding electrically neutral compound HO is the hydroxyl radical. The corresponding covalently bound group –OH of atoms is the hydroxy group. Both the hydroxide ion and hydroxy group are nucleophiles and can act as catalysts in organic chemistry.

<span class="mw-page-title-main">Ammonium</span> Chemical compound

Ammonium is a modified form of ammonia that has an extra hydrogen atom. It is a positively charged (cationic) molecular ion with the chemical formula NH+4 or [NH4]+. It is formed by the addition of a proton to ammonia. Ammonium is also a general name for positively charged (protonated) substituted amines and quaternary ammonium cations, where one or more hydrogen atoms are replaced by organic or other groups. Not only is ammonium a source of nitrogen and a key metabolite for many living organisms, but it is an integral part of the global nitrogen cycle. As such, human impact in recent years could have an effect on the biological communities that depend on it.

<span class="mw-page-title-main">Basic copper carbonate</span> Chemical compound

Basic copper carbonate is a chemical compound, more properly called copper(II) carbonate hydroxide. It can be classified as a coordination polymer or a salt. It consists of copper(II) bonded to carbonate and hydroxide with formula Cu2(CO3)(OH)2. It is a green solid that occurs in nature as the mineral malachite. It has been used since antiquity as a pigment, and it is still used as such in artist paints, sometimes called verditer, green bice, or mountain green.

<span class="mw-page-title-main">Malachite</span> Mineral variety of copper carbonate

Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.

<span class="mw-page-title-main">Lead(II) sulfate</span> Chemical compound

Lead(II) sulfate (PbSO4) is a white solid, which appears white in microcrystalline form. It is also known as fast white, milk white, sulfuric acid lead salt or anglesite.

<span class="mw-page-title-main">Chalcanthite</span> Sulfate mineral

Chalcanthite (from Ancient Greek χάλκανθον (khálkanthon), from χαλκός (khalkós) 'copper' and ἄνθος (ánthos) 'flower, bloom') is a richly colored blue-green water-soluble sulfate mineral CuSO4·5H2O. It is commonly found in the late-stage oxidation zones of copper deposits. Due to its ready solubility, chalcanthite is more common in arid regions.

<span class="mw-page-title-main">Copper(II) oxide</span> Chemical compound – an oxide of copper with formula CuO

Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide). As a mineral, it is known as tenorite, or sometimes black copper. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds.

Classical qualitative inorganic analysis is a method of analytical chemistry which seeks to find the elemental composition of inorganic compounds. It is mainly focused on detecting ions in an aqueous solution, therefore materials in other forms may need to be brought to this state before using standard methods. The solution is then treated with various reagents to test for reactions characteristic of certain ions, which may cause color change, precipitation and other visible changes.

<span class="mw-page-title-main">Tetraamminecopper(II) sulfate</span> Chemical compound

Tetraamminecopper(II) sulfate monohydrate, or more precisely tetraammineaquacopper(II) sulfate, is the salt with the formula [Cu(NH3)4]SO4·H2O, or more precisely [Cu(NH3)4(H2O)]SO4. This dark blue to purple solid is a sulfuric acid salt of the metal complex [Cu(NH3)4(H2O)]2+ (tetraammineaquacopper(II) cation). It is closely related to Schweizer's reagent, which is used for the production of cellulose fibers in the production of rayon.

<span class="mw-page-title-main">Iron(II) hydroxide</span> Chemical compound

Iron (II) hydroxide or ferrous hydroxide is an inorganic compound with the formula Fe(OH)2. It is produced when iron (II) salts, from a compound such as iron(II) sulfate, are treated with hydroxide ions. Iron(II) hydroxide is a white solid, but even traces of oxygen impart a greenish tinge. The air-oxidised solid is sometimes known as "green rust".

<span class="mw-page-title-main">Antlerite</span> Copper sulfate mineral

Antlerite is a greenish hydrous copper sulfate mineral, with the formula Cu3(SO4)(OH)4. It occurs in tabular, acicular, or fibrous crystals with a vitreous luster. Originally believed to be a rare mineral, antlerite was found to be the primary ore of the oxidised zones in several copper mines across the world, including the Chuquicamata mine in Chile, and the Antler mine in Arizona, US from which it takes its name. It is chemically and optically similar in many respects to other copper minerals such as malachite and brochantite, though it can be distinguished from the former by a lack of effervescence in hydrochloric acid.

A nitrate test is a chemical test used to determine the presence of nitrate ion in solution. Testing for the presence of nitrate via wet chemistry is generally difficult compared with testing for other anions, as almost all nitrates are soluble in water. In contrast, many common ions give insoluble salts, e.g. halides precipitate with silver, and sulfate precipitate with barium.

<span class="mw-page-title-main">Calcium diglutamate</span> Chemical compound

Calcium diglutamate, sometimes abbreviated CDG and also called calcium biglutamate, is a compound with formula Ca(C5H8NO4)2. It is a calcium acid salt of glutamic acid. CDG is a flavor enhancer (E number E623)—it is the calcium analog of monosodium glutamate (MSG). Because the glutamate is the actual flavor-enhancer, CDG has the same flavor-enhancing properties as MSG but without the increased sodium content. Notably, only the L isomer is used in flavouring as D-glutamate does not have an umami/savoury flavour.

In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.

<span class="mw-page-title-main">Schweizer's reagent</span> Chemical compound

Schweizer's reagent is a metal ammine complex with the formula [Cu(NH3)4(H2O)2](OH)2. This deep-blue compound is used in purifying cellulose. This salt consists of tetraamminediaquacopper(II) cations and hydroxide anions.

<span class="mw-page-title-main">Cobalt(II) carbonate</span> Chemical compound

Cobalt(II) carbonate is the inorganic compound with the formula CoCO3. This pink paramagnetic solid is an intermediate in the hydrometallurgical purification of cobalt from its ores. It is an inorganic pigment, and a precursor to catalysts. Cobalt(II) carbonate also occurs as the rare red/pink mineral spherocobaltite.

<span class="mw-page-title-main">Copper(II) carbonate</span> Chemical compound

Copper(II) carbonate or cupric carbonate is a chemical compound with formula CuCO
3
. At ambient temperatures, it is an ionic solid consisting of copper(II) cations Cu2+
and carbonate anions CO2−
3
.

<span class="mw-page-title-main">Chevreul's salt</span> Chemical compound

Chevreul's salt (copper(I,II) sulfite dihydrate, Cu2SO3•CuSO3•2H2O or Cu3(SO3)2•2H2O), is a copper salt which was prepared for the first time by a French chemist Michel Eugène Chevreul in 1812. Its unusual property is that it contains copper in both of its common oxidation states, making it a mixed-valence complex. It is insoluble in water and stable in air. What was known as Rogojski's salt is a mixture of Chevreul's salt and metallic copper.

References

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