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|Molar mass||187.57 g/mol,
|Density||2.32 g/cm3 (anhydrous)|
|Solubility in water||138 g/100 mL (0 °C) trihydrate|
|R-phrases||R22 R36/37/38 R48/20/21/22 R66|
|Main hazards||Toxic, irritant|
|Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)|
Copper(II) nitrate is the chemical compound with the formula Cu(NO3)2. Commonly referred to simply as copper nitrate, the anhydrous form is a blue, crystalline solid. Hydrated forms of copper nitrate, also blue, are commonly used in school laboratories to demonstrate chemical voltaic cell reactions. The hydrated and anhydrous species have remarkably different properties, illustrating the effect of water of crystallization.
The Roman numeral sign is to specify that the copper has an oxidation state of +2.
Hydrated and anhydrous copper nitrates behave differently.
The bright blue anhydrous material, Cu(NO3)2, is a volatile solid, subliming in a vacuum. In the gas-phase, Cu(NO3)2 is square planar, each Cu centre being surrounded by four oxygen atoms. Upon condensation, this monomer polymerizes.
Hydrated copper nitrate
Copper nitrate can be used to generate nitric acid by heating it until decomposition and passing the fumes directly into water. This method is similar to the last step in the Ostwald process. The equations are as follows:
Copper nitrate soaked splints of wood burn with an emerald green flame. Addition of Magnesium nitrate gives a lime green colour.
Cu(NO3)2 forms when copper metal is treated with N2O4:
- Cu + 2 N2O4 → Cu(NO3)2 + 2 NO
It can also be formed by reacting copper metal with an aqueous solution of silver nitrate, see this page for more info.
Use in organic synthesis
Copper nitrate, in combination with acetic anhydride, is an effective reagent for nitration of aromatic compounds, under what are known as "Menke conditions", in honour of the Dutch chemist who discovered that metal nitrates are effective reagents for nitration. Hydrated copper nitrate absorbed onto clay affords a reagent called "claycop". The resulting blue clay is used as a slurry, for example for the oxidation of thiols to disulfides. Claycop is also used to convert dithioacetals to carbonyls. A related reagent based on Montmorillonite has proven useful for the nitration of aromatic compounds.