Copper(II) bromide
From Wikipedia the free encyclopedia
 Anhydrous | |
 Tetrahydrate | |
| Names | |
|---|---|
| Other names Cupric bromide Copper dibromide | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider | |
| ECHA InfoCard | 100.029.243 |
| EC Number |
|
PubChem CID | |
| UNII | |
CompTox Dashboard (EPA) | |
| |
| |
| Properties | |
| 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) |
| 55.7 g/100 mL (20 °C) | |
| Solubility | Soluble in alcohol, acetone, ammonia, insoluble in benzene, ether, ethyl ether, sulfuric acid |
| +685.5·10−6 cm3/mol | |
| Structure | |
| monoclinic | |
| Hazards | |
| NFPA 704 (fire diamond) | |
| NIOSH (US health exposure limits): | |
PEL (Permissible) | TWA 1 mg/m3 (as Cu)[1] |
REL (Recommended) | TWA 1 mg/m3 (as Cu)[1] |
IDLH (Immediate danger) | TWA 100 mg/m3 (as Cu)[1] |
| Related compounds | |
Other anions | Copper(II) fluoride Copper(II) chloride |
Other cations | Copper(I) bromide Nickel(II) bromide Zinc bromide Cadmium bromide Mercury(II) bromide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Copper(II) bromide (CuBr2) is a chemical compound that forms an unstable tetrahydrate CuBr2·4H2O. It is used in photographic processing as an intensifier and as a brominating agent in organic synthesis.[2]
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.[3] 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:[4]
- CuO + 2HBr → CuBr2 + H2O.
The tetrahydrate can be produced by recrystallization of solutions of copper(II) bromide at 0 °C. If heated above 18 °C, it releases water to produce the anhydrous form.[5]
Purification
[edit]Copper(II) bromide is purified by crystallization twice from water, filtration to remove any CuBr and concentration under vacuum. This product is dehydrated using phosphorus pentoxide.[6]
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'.[7] CuBr2 monomeric units are present in the gas phase at high temperature.[8]
The tetrahydrate, structurally formulated as [CuBr2(H2O)2]·2H2O, has a monoclinic crystal structure and consists of distorted square planartrans-[CuBr2(H2O)2] centres as well as two molecules of water.[5]
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.[9]
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.[10]
Usage
[edit]Copper(II) bromide lasers produce pulsed yellow and green light and have been studied as a possible treatment for cutaneous lesions.[11] Experiments have also shown copper bromide treatment to be beneficial for skin rejuvenation.[12] It has been widely used in photography as its solution was used as the bleaching step for intensifying collodion and gelatin negatives.[13] Copper(II)bromide has also been proposed as a possible material in humidity indicator cards.[14]
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.
Natural occurrence
[edit]Pure copper(II) bromide is as yet (2020) unknown among minerals. However, barlowite, Cu4BrF(OH)6, contains both copper and bromide.[15][16]
See also
[edit]References
[edit]- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0150". National Institute for Occupational Safety and Health (NIOSH).
- ^ Huang, Jianhui; Macdonald, Simon J. F.; Harrity, Joseph P. A. (2009). "A cycloaddition route to novel triazole boronic esters". Chem. Commun. (4): 436–438. doi:10.1039/b817052e. PMID 19137177.
- ^ Livingstone, E. S.; Maitland, A. (1991). "A high power, segmented metal, copper bromide laser". Measurement Science and Technology. 2 (11): 1119. Bibcode:1991MeScT...2.1119L. doi:10.1088/0957-0233/2/11/022. ISSN 0957-0233. S2CID 250801465.
- ^ Breitinger, D. K.; Herrmann, W. A., eds. (1999). Synthetic methods of Organometallic and Inorganic Chemistry. New York: Thieme Medical Publishers. ISBN 0-86577-662-8.
- ^ a b Kenji Waizumi; Hideki Masuda; Hitoshi Ohtaki (1992). "X-ray structural studies of FeBr2·4H2O, CoBr2·4H2O, NiCl2·4H2O and CuBr2·4H2O. cis/trans selectivity in transition metal(II) dihalide tetrahydrate". Inorganica Chimica Acta. 192 (2): 173–181. doi:10.1016/S0020-1693(00)80756-2.
- ^ 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.
- ^ Helmholz, Lindsay (1947). "The Crystal Structure of Anhydrous Cupric Bromide". J. Am. Chem. Soc. 69 (4): 886–889. doi:10.1021/ja01196a046.
- ^ Conry, Rebecca R. (2006). "Copper: Inorganic & Coordination Chemistry". Encyclopedia of Inorganic Chemistry (2nd ed.). John Wiley & Sons. doi:10.1002/0470862106.ia052. ISBN 978-0-470-86210-0.
- ^ King, L. Carroll; Ostrum, G. Kenneth (1964). "Selective Bromination with Copper(II) Bromide". J. Org. Chem. 29 (12): 3459–3461. doi:10.1021/jo01035a003.
- ^ Rodebaugh, Robert; Debenham, John S.; Fraser-Reid, Burt J.; Snyder, James P. (1999). "Bromination of Alkenyl Glycosides with Copper(II) Bromide and Lithium Bromide: Synthesis, Mechanism, and DFT Calculations". J. Org. Chem. 64 (5): 1758–1761. doi:10.1021/jo9718509. PMID 11674253.
- ^ McCoy, S.; Hanna, M.; Anderson, P.; McLennan, G.; Repacholi, M. (June 1996). "An evaluation of the copper-bromide laser for treating telangiectasia". Dermatol. Surg. 22 (6): 551–7. doi:10.1111/j.1524-4725.1996.tb00373.x. ISSN 1076-0512. PMID 8646471. S2CID 22626280.
- ^ 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.
- ^ Diane Heppner The Focal Encyclopedia of Photography, Inc. Elsevier 20074th edition
- ^ George McKedy US Patent Application Publication, Pub.No.: US2010/0252779 A1
- ^ "Verification".
- ^ "List of Minerals". 21 March 2011.