Copper benzoate describes chemical compound with the formula . 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.
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, 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. A hydrated form is also known, wherein each Cu(II) centre is bound to four water ligands and a bidentate O, O-benzoate.
Copper benzoate trihydrate can be made by combining aqueous solutions of sodium benzoate and copper sulfate, forming a pale blue precipitate:
The "ñ form" of the anhydrous compound is prepared by vacuum desiccation of the trihydrate at 95 ðC with phosphorus pentoxide. The "ò form" is obtained by heating the monoethanol derivative in air at 90 ðC. The "ó form" is obtained by heating the monoethanol derivative in boiling carbon tetrachloride for a few hours. All are described as "blue-green crystalline powders."
It has found some niche use as a combination fuel and source of copper ion for blue light production in fireworks. It is not on the list of chemicals approved in consumer fireworks in the US.
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.
A tetrakis[copper(I) benzoate] has been characterized.
Copper(II) benzoate forms many addition compounds. Examples include copper(II) benzoate mono(benzoic acid) and the adducts with ethanol and urea.