Copper(II) bromide

From Wikipedia, the free encyclopedia
Jump to: navigation, search
Copper (II) bromide
Copper (II) bromide
Identifiers
CAS number 7789-45-9 YesY
PubChem 24611
ChemSpider 8395631 YesY
Jmol-3D images Image 1
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 (928 °F; 771 K)
Boiling point 900 °C (1,650 °F; 1,170 K)
Solubility in water 55.7 g/100 mL (20 °C)
Solubility in [[alcohol, acetone, ammonia]] soluble
Solubility in [[benzene, ether, ethyl ether, sulfuric acid]] insoluble
Structure
Crystal structure monoclinic
Hazards
EU Index Not listed
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Related compounds
Other anions Copper(II) fluoride
Copper(II) chloride
Other cations Nickel(II) bromide
Copper(I) bromide
Zinc bromide
Cadmium bromide
Mercury(II) fluoride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
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 reacting with the copper discharge tube.[2] Producing yellow or green light, it is used in dermatological applications.

Synthesis[edit]

Copper(II) bromide can be obtained by combining copper oxide and hydrobromic acid:[3]

CuO + 2HBr → CuBr2 + H2O.

Purification[edit]

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[edit]

In the solid state CuBr2 has a polymeric structure, with CuBr4 planar units connected on opposite sides to form chains. The crystal structure is monoclinic, space group C2/m, with lattice constants a = 714 pm, b = 346 pm, c = 718 pm, e ß = 121° 15'.[5] CuBr2 monomeric units are present in the gas phase at high temperature.[6]

Reactions[edit]

Copper (II) bromide in chloroform-ethyl acetate reacts with ketones resulting in the formation of 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 formation of α-bromo ketones.[7]

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.[8]

Usage[edit]

Copper(II) bromide lasers produce pulsed yellow and green light and have been studied as a possible treatment for cutaneous lesions.[9] Experiments have also shown copper bromide treatment to be beneficial for skin rejuvenation.[10] It has been widely used in photography as its solution was used as the bleaching step for intensifying collodion and gelatin negatives.[11] Copper(II)bromide has also been proposed as a possible material in humidity indicator cards.[12]

Safety[edit]

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[edit]

References[edit]

  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. ^ Helmholz L. The Crystal Structure of Anhydrous Cupric Bromide J. Am. Chem. Soc. 1947 69 (4), 886–889. DOI:10.1021/ja01196a046
  6. ^ Conry, RR. Copper: Inorganic & Coordination Chemistry in Encyclopedia of Inorganic Chemistry, 2nd ed., John Wiley & Sons, 2006. DOI:10.1002/0470862106.ia052, ISBN 9780470862100
  7. ^ Carroll King L., Ostrum K Selective Bromination with Copper(II) Bromide The J. of Org. Chem. 1964 29 (12), 3459-3461.
  8. ^ 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
  9. ^ 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.
  10. ^ 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.
  11. ^ Diane Heppner The Focal Encyclopedia of Photography, Inc. Elsevier 20074th edition
  12. ^ George McKedy US Patent Application Publication, Pub.No.: US2010/0252779 A1

http://msds.chem.ox.ac.uk/CO/copper_II_bromide.html