Copper(II) chloride

Monoclinic ( CuCl2, anhydrous)

A = 690 pm b = 330 pm; β = 122.20 ° c = 682 pm

Cu, Cl

  • Copper chloride
  • Copper (II ) chloride dihydrate ( CuCl2 · 2 H2O)
  • CuCl2
  • CuCl2 · 2 H2O (dihydrate )
  • 7447-39-4
  • 10125-13-0 (dihydrate )

Brown powder blue - green powder (dihydrate )

Fixed

  • 3.39 g · cm -3
  • 2.51 g · cm -3

630 ° C ( anhydrous)

422 g · l-1 (20 ° C ) in water

Attention

0.1 mg · m-3

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Copper ( II) chloride is a chemical compound and a copper salt of the acid having the formula CuCl2. Crystal Anhydrous copper (II ) chloride is a brown powder that is highly hygroscopic. The incorporation of water molecules in its crystal structure is formed, the copper (II ) chloride dihydrate, a blue- green solid with the formula CuCl2 · 2 H2O. The crystal anhydrous copper chloride dissolves in moist air to a brown mush, while the dihydrate is stable in air. By heating to about 100 ° C, the water of crystallization is driven from the dihydrate, and the brown, water- free form remains.

There is also the basic copper (II ) chloride ( copper (II) oxychloride, Cu2Cl (OH ) 3) which is insoluble in water and is referred to as the tetrahydrate as Braunschweig green.

All compounds show in a burner flame a blue-green flame coloration, caused by the Cu2 ions.

Occurrence

Copper (II ) chloride occurs in nature as the mineral Tholbachit, the dihydrate is also known as mineral Eriochalcit. Both compounds are also often associated with copper ore Atacamit.

Production and representation

In the laboratory can be prepared copper ( II) chloride, copper (II ) oxide and hydrochloric acid:

Technically, it is obtained by chlorination of copper sheet.

Copper ( II) chloride can also be prepared by a simple electrolysis of sodium chloride with copper electrodes. The chlorine electrolysis then connects directly to the copper electrode. Evaporation produced copper ( II) chloride dihydrate.

Properties

Anhydrous copper ( II) chloride occurs in the form of a brown to yellow powder; the dihydrate is turquoise. Both produce a green flame coloration due to the contained copper ions ( Cu2 ).

The anhydrous copper (II ) chloride crystallizes in the monoclinic crystal system with space group C2 / m in a distorted CdI2 structure. The distortion of the structure caused by the Jahn -Teller effect caused by the valence electron ( d9 ) of Cu2 ions is produced. The anhydrous copper ( II) chloride was the first compound, in which a coordination polyhedron in the shape of a ( distorted) octahedron made ​​of six chloride anions could be detected by a Cu2 ion.

The copper (II ) chloride dihydrate, however, crystallizes in the orthorhombic crystal system, space group pBMN. The Cu2 ion will be here by four Cl - ions surrounded a square-planar, the two remaining corners of the distorted octahedron are occupied by water molecules.

Use

Copper chloride is used as a catalyst in organic synthesis, for example in the production of the textile dye aniline black, and oxychlorination. In addition, you use it in pyrotechnics to produce green flames, with the copper etching ( in a mixture with hydrochloric acid ), used in photography as fading of negatives, as basic copper chloride in orchards and vineyards against fungal diseases and the Chimney-sweeping of oil furnaces.

Proof

Copper ( II) chloride is detected with ammonia water. This falls out of blue copper (II ) hydroxide, which on further addition again comes off as Tetraamminkupfer.

Lattice constant Coordination number CAS registry number Dangerous Substances Directive (67/548/EEC) Atacamite Jahn–Teller effect Coordination geometry Copper(I) fluoride Copper(I) bromide Copper(I) iodide Copper(II) fluoride Copper(II) bromide
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