Copper benzoate
Chemical compound
From Wikipedia, the free encyclopedia
Copper benzoate describes chemical compound with the formula Cu(C6H5CO2)2(H2O)n. They consist of coordination complexes derived from the cupric ion and the conjugate base of benzoic acid. Many derivatives are known with diverse ancillary ligands.[4]
aq4benzoate.svg)
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| Names | |
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| IUPAC name
copper dibenzoate | |
| Other names
cupric benzoate | |
| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.007.776 |
PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| Molar mass | |
| Appearance | blue solid |
| Density | 1.197 g/cm3 |
| Hazards | |
| GHS labelling:[1] | |
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| Warning | |
| H315, H319, H335 | |
| P261, P305+P351+P338 | |
| Flash point | 111.4 °C (232.5 °F; 384.5 K) |
| NIOSH (US health exposure limits):[3] | |
PEL (Permissible) |
TWA 1 mg/m3 (as Cu) |
REL (Recommended) |
TWA 1 mg/m3 (as Cu) |
IDLH (Immediate danger) |
TWA 100 mg/m3 (as Cu) |
| Related compounds | |
Other anions |
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Other cations |
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Related compounds |
Phenylcopper |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Structure
4(aq)2.svg)
Copper(II) benzoate exists in at least two structural forms, depending on the degree of hydration. Resembling copper(II) acetate, one form of copper benzoate adopts a "Chinese lantern" structure,[5] wherein a pair of copper centers are linked by four bridging carboxylate ligands. Typically, one site on each copper center is occupied by water, which can be replaced by other ligands.[6] A hydrated form is also known, wherein each Cu(II) centre is bound to four water ligands and a bidentate O, O-benzoate.[7]
Preparation
Trihydrate
Copper benzoate trihydrate can be made by combining aqueous solutions of sodium benzoate and copper sulfate, forming a pale blue precipitate:[8]
- 4 K(C6H5CO2) + 2 CuSO4·5H2O → Cu2(C6H5CO2)4(H2O)2 + 2 K2SO4 + 8 H2O
Anhydrous forms
The "α form" of the anhydrous compound is prepared by vacuum desiccation of the trihydrate at 95 °C with phosphorus pentoxide.[8] The "β form" is obtained by heating the monoethanol derivative in air at 90 °C.[8] The "γ form" is obtained by heating the monoethanol derivative in boiling carbon tetrachloride for a few hours.[8] All are described as "blue-green crystalline powders."
Uses
It has found some niche use as a combination fuel and source of copper ion for blue light production in fireworks.[9] It is not on the list of chemicals approved in consumer fireworks in the US.[10]
It is also used in two-part dental adhesives, in polyester resin compositions to increase thermal resistance and decrease gelation, and as a metal-based hydrogen sulfide scavenger in asphalt.[1]