Copper(I) bromide
Chemical compound
From Wikipedia, the free encyclopedia
Copper(I) bromide is the chemical compound with the formula CuBr. This white diamagnetic solid adopts a polymeric structure akin to that for zinc sulfide. The compound is widely used in the synthesis of organic compounds and as a lasing medium in copper bromide lasers.
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| Names | |
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| Other names
Cuprous bromide | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.029.210 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties[1] | |
| CuBr | |
| Molar mass | 143.450 g·mol−1 |
| Appearance | white powder |
| Density | 4.98 g/cm3 |
| Melting point | 483 °C (901 °F; 756 K) |
| Boiling point | 1,345 °C (2,453 °F; 1,618 K) |
| 0.0012 g/100 g (20 °C (68 °F)) | |
Solubility product (Ksp) |
6.27×10−9 |
| Band gap | 1.00 eV[2] |
| −49.0×10−6 cm3/mol | |
Refractive index (nD) |
2.116[citation needed] |
| Structure[2] | |
| Tetragonal [129] | |
| P4/nmm | |
| 4/mmm | |
a = 3.85 Å, b = 3.85 Å, c = 6.04 Å α = 90°, β = 90°, γ = 90° | |
Lattice volume (V) |
89.78 Å3 |
Formula units (Z) |
2 |
| Tetrahedral at Cu1+ | |
| Thermochemistry[1] | |
Heat capacity (C) |
54.7 J⋅mol−1⋅K−1 |
Std molar entropy (S⦵298) |
96.1 J⋅mol−1⋅K−1 |
Std enthalpy of formation (ΔfH⦵298) |
−104.6 kJ⋅mol−1 |
Gibbs free energy (ΔfG⦵) |
−100.8 kJ⋅mol−1 |
Enthalpy of fusion (ΔfH⦵fus) |
5.1 kJ⋅mol−1 |
| Hazards | |
| GHS labelling:[3] | |
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| Danger | |
| H302+H312, H315, H318, H410 | |
| P264, P270, P273, P280, P301+P312+P330, P302+P352+P312, P305+P351+P338+P310, P332+P313, P362, P391, P501 | |
| NFPA 704 (fire diamond) | |
Threshold limit value (TLV) |
1 mg/m3[4] (TWA) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
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| NIOSH (US health exposure limits):[5] | |
PEL (Permissible) |
1 mg/m3 (TWA, as Cu) |
REL (Recommended) |
1 mg/m3 (TWA, as Cu) |
IDLH (Immediate danger) |
100 mg/m3 (as Cu) |
| Related compounds | |
Other anions |
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Other cations |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Properties
The compound is white, although samples are often colored due to the presence of copper(II) impurities.[6][page needed] The copper(I) ion also oxidizes easily in air. CuBr is insoluble in most solvents due to its polymeric structure, which features four-coordinated, tetrahedral Cu centers interconnected by bromide ligands (ZnS structure).
Thermal excitation of copper(I) bromide vapour yields a blue-violet emission which is of greater saturation than known copper(I) chloride emission.[7] Copper(I) bromide is hence an advantageous emitter in pyrotechnic flames.
Preparation
It is commonly prepared by the reduction of cupric salts with sulfite in the presence of bromide.[8] For example, the reduction of copper(II) bromide with sulfite yields copper(I) bromide and hydrogen bromide:
- 2 CuBr2 + H2O + SO2−3 → 2 CuBr + SO2−4 + 2 HBr
Applications in organic chemistry
In the Sandmeyer reaction, CuBr is employed to convert diazonium salts into the corresponding aryl bromides:[8]
- ArN+2 + CuBr → ArBr + N2 + Cu+
The aforementioned complex CuBr(S(CH3)2) is widely used to generate organocopper reagents.[9] Related CuBr complexes are catalysts for atom transfer radical polymerization (ATRP) and copper-catalyzed cross dehydrogenative couplings (CDCs).[citation needed]
Reactions
Upon treatment with Lewis bases, CuBr converts to molecular adducts. For example, with dimethyl sulfide (S(CH3)2), the colorless complex is formed:[9]
- CuBr + S(CH3)2 → CuBr(S(CH3)2)
In this coordination complex, the copper is two-coordinate, with a linear geometry. Other soft ligands afford related complexes. For example, triphenylphosphine (P(C6H5)3) gives CuBr(P(C6H5)3), although this species has a more complex structure.[citation needed]
