2. Copper basic carbonate was prepared by leaving copper hydroxide in open air for 48 hours.
Preparation of tricopper dicitrate (Cu3(C6H5O7)2)
1. By reacting Copper (II) basic carbonate (Cu2(OH)2CO3)
with citric acid monohydrate (C6H8O7 • H2O) in water solution
The equation:
3Cu2(OH)2CO3 + 4C6H8O7 → 2Cu3(C6H5O7)2↓ + 9H2O + 3CO2↑
1. Copper hydroxide was prepared by electrolysis of potassium sulfate solution using copper electrodes.
Cu + 2H2O ―electrolysis→ Cu(OH)2 + H2↑
Cu - 2e-Cu+2
Cu+2 + 2OH- → Cu(OH)2
2H+ + 2e- → H2
Reaction of oxidation of OH- to H2O and O2 does not occur because presence of Cu+2 ions and reaction between them.
Electrolysis was handled with 3.3V potential difference between electrodes. Average current was slightly above 150mA with 1 peak to 200mA (measure limit). More precise data in adjacent MS Excel file.
2. Copper basic carbonate was prepared by leaving copper hydroxide in open air for 48 hours.
2Cu(OH)2 + CO2 → Cu2(OH)2CO3 + H2O
After collecting and grinding CBC powder was left for another 24 hours to fully complete the reaction.
3. The final step was reaction between citric acid monohydrate solution with copper basic carbonate. The internet source www.sciencemadness.org wrote that copper citrate has a low solubility in water and can be easily prepared by reaction of copper oxide/hydroxide with citric acid. However, in the reaction was not observed any bubbling aka gas production and after all copper basic carbonate has reacted in the reaction mix was not any precipitate, which should have formed. After leaving reaction mix for 24 hours any precipitate has not been formed, so were made an assumption, that copper citrate stayed in solution because of big quantities of water.
4. Water was evaporated to about 10ml mark, and water and citric syrup was left overnight for copper citrate to precipitate. Nothing has precipitated or crystalized, so were decided to neutralize leftover citric acid, because copper citrate might be soluble in it.
5. The syrup was diluted with water and neutralized using sodium bicarbonate (NaHCO3), but no precipitate has not formed after course of another 24 hours.
C6H8O7 + 3NaHCO3 → Na3C6H5O7 + 3H2O + 3CO2↑
Conclusion: although reaction did occur none precipitate has been formed. This leads to two theories:
1 - the end product was not copper citrate (probably false because of reaction mix color)
2 - solubility of copper citrate is higher in citric acid solutions and formation requires longer time or special conditions.
2nd attempt??
2. By reaction of copper (II) ethanoate (Cu(CH3COO)2)
with citric acid