Copper (II) bromide
Other names Cupric bromide
Identifiers
CAS number	7789-45-9 Y
PubChem	24611
ChemSpider	8395631 Y
Jmol-3D images	Image 1
SMILES [Cu+2].[Br-].[Br-]
InChI InChI=1S/2BrH.Cu/h2*1H;/q;;+2/p-2 Y Key: QTMDXZNDVAMKGV-UHFFFAOYSA-L Y InChI=1/2BrH.Cu/h2*1H;/q;;+2/p-2 Key: QTMDXZNDVAMKGV-NUQVWONBAD
Properties
Molecular formula	CuBr2
Molar mass	223.37 g/mol
Appearance	grayish black crystals deliquescent
Density	4.710 g/cm3, solid
Melting point	498 °C, 771 K, 928 °F
Boiling point	900 °C, 1173 K, 1652 °F
Solubility in water	55.7 g/100 mL (20 °C)
Structure
Crystal structure	monoclinic
Hazards
EU Index	Not listed
NFPA 704	0 2 0
Related compounds
Other anions	copper(II) fluoride copper(II) chloride
Other cations	nickel(II) bromide copper(I) bromide zinc bromide
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Copper(II) bromide (CuBr₂) is a chemical compound. It is used in photographic processing as an intensifier and as a brominating agent in organic synthesis.^[1]

It is also used in the Copper vapor laser, a class of laser where the medium is copper bromide vapour formed in situ from hydrogen bromide in reaction with the enclosing copper discharge tube.^[2] Producing yellow or green light, it is used in dermatological applications.

  Synthesis

Copper(II) bromide can be obtained by combining copper oxide and hydrobromic acid: CuO + 2HBr -> CuBr₂ + H₂O.^[3]

  Purification

Copper(II) bromide is purified by crystallisation twice from water, filtration to remove any CuBr and concentration under vacuum. This product is dehydrated using phosphorus pentoxide. ^[4]

  Molecular and crystal structure

The crystal structures of Cu₂Br₆ dimers were obtained. Copper (II) centers each perform D₂d geometry with a geometry intermediate between tetrahedral and square planar. The crystal structures exhibit two phases: the orange and the green. Under the application of a small force such as pressure the orange phase can transform to the green phase. Upon heating to 90^ْC the green phase can change into the orange. With the correlation of polarized absorption spectral data and X-ray crystallography it was determined that the color variance is due to the different orientation of the dimer phases.^[5]

  Reactions

Copper (II) bromide in chloroform-ethyl acetate reacts with ketones resulting in alpha-bromo ketones. The resulting product can be directly used for the preparation of derivatives. This heterogeneous method is reported to be the most selective and direct method of α-bromo ketones formation.^[6]

Dibromination of NPGs, n-pentenyl glycosides, using CuBr₂/LiBr reagent combination was performed in order for an NPG to serve as a glycosyl acceptor during halonium-promoted couplings. Such reaction gives high yield of the dibromides from alkenyl sugars that are resistant to a direct reaction with molecular bromine.^[7]

  Usage

Lasers with Copper (II) bromide stream produce pulsed yellow and green light and are studied as a possible way of treatment of cutaneous lesions.^[8] Experiments have also shown a great effect of Copper Bromide treatment on skin rejuvenation.^[9] It has been widely used in photography as its solution was used as the bleaching step for intensifying collodion and gelatin negatives.^[10] There are also proposals of using Copper (II) bromide in humidity indicating cards ^[11]

  Safety

Copper(II) bromide is harmful if swallowed. It affects the central nervous system, brain, eyes, liver, and kidneys. It causes irritation to skin, eyes, and respiratory tract.

  See also

• Copper(I) bromide (CuBr)

  References

1. ^ A cycloaddition route to novel triazole boronic esters Jianhui Huang, Simon J. F. Macdonald and Joseph P. A. Harrity, Chem. Commun., 2009, 436–438, doi: 10.1039/b817052e
2. ^ [1]
3. ^ Synthetic methods of Organometallic and Inorganic Chemistry D.K.Breitinger.W.A.Herrmann Thieme Medical Publishers, Inc New York 1999, ISBN 0856776628
4. ^ Hope et al. J Chem Soc 5226 1960, Glemser & Sauer in Handbook of Preparative Inorganic Chemistry (Ed.Brauer) Academic Press Vol II p 1009 1965.
5. ^ Scott B., Willett R.A copper(II) bromide dimer system exhibiting piezochromic and thermochromic properties: the crystal structure and electronic spectroscopy of the two room-temperature phases of bis(tetrapropylammonium) hexabromodicuprate(II) J.of the American Chem. Soc. 1991 113 (14), 5253-5258
6. ^ Carroll King L., Ostrum K Selective Bromination with Copper(II) Bromide The J. of Org. Chem. 1964 29 (12), 3459-3461.
7. ^ Rodebaugh R, Debenham J, Fraser-Reid B.,Snyder J. The J.of Org.Chem. 1999 64 (5), 1758-1761 Bromination of Alkenyl Glycosides with Copper(II) Bromide and Lithium Bromide:  Synthesis, Mechanism, and DFT Calculations
8. ^ McCoy S, Hanna M, Anderson P, McLennan G, Repacholi M. Dermatol Surg. 1996 Jun; 22(6):551-7. An evaluation of the copper-bromide laser for treating telangiectasia.
9. ^ Davis P., Town G., Haywards H. A practical comparison of IPLs and the Copper Bromide Laser for photorejuvenation, acne and the treatment of vascular&pigmented lesions.
10. ^ Diane Heppner The Focal Encyclopedia of Photography, Inc. Elsevier 20074th edition
11. ^ George McKedy US Patent Application Publication, Pub.No.: US2010/0252779 A1

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