Copper(II) bromide

Deliquescent black crystals

Fixed

4.71 g · cm -3

498 ° C

900 ° C

• Readily soluble in water ( 557 g / l at 20 ° C)
• Soluble in ethanol and ethyl acetate
• Not soluble in benzene and diethyl ether

Risk

0.1 mg/m3

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Copper (II ) bromide is a copper salt of the hydrogen bromide with the ratio formula CuBr2. Copper has here the 2 oxidation state.

Representation

Copper ( II) bromide may be obtained from the elements.

Also possible is the preparation of copper ( II) oxide, and hydrobromic acid and copper (II ) chloride, and boron (III ) bromide.

Properties

Copper (II ) bromide is a greenish - black and hygroscopic solid, which causes a green flame color. It is responsible for the green flame positive Beilstein test, is formed in the copper ( II) bromide according to the above reaction. It crystallizes in the cadmium iodide structure. Upon heating, the copper (II ) bromide decomposes with the release of bromine with copper ( I) bromide:

It has a monoclinic crystal structure with space group C2 / m (a = 7.18 Å, b = 3.46 Å, c = 7.14 Å, ß = 121 ° 15 ') and an enthalpy of formation of -139.7 kJ / mol.

Solubility

Copper (II ) bromide is relatively well soluble in water. At temperatures below 18.0 ° C crystallized copper (II ) bromide as a green tetrahydrate in the form of monoclinic prisms made about it in the anhydrous form as black rhombohedron.

Dilute solutions are blue, concentrated green to dark brown.

Use

In the organic chemistry synthesis ketones can be brominated with copper ( II) bromide for α - bromo ketones.