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Author: Subject: Copper Formate
Zephyr
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[*] posted on 6-12-2013 at 17:38
Copper Formate

Several days ago while attempting to make Formaldehyde via calcium Formate, I thought it might be interesting to synthesize some Copper Formate.
First I dissolved 15g of CuSO4 in boiling water.
After the solution had cooled to 60oC I added 46g of Formic acid per the stoicheometry of the reaction;

CuSO4 + 2CH2O2 ---> C2H2CUO4 + ?

The solution was then cooled to 10oC in an ice bath and left to crystallize. I also made an identical solution of CuSO4 to compare it to.

The one on the left is copper sulfate and the one on the right is the right is hopefully Copper Formate.


I found Cupric Formate(2640) in the Merck index.
"C2H2CuO4;molar weight 153.58"
"prepared from cupric carbonate and Formic acid"
"Very pale blue monoclinic crystals"

To verify the identity of the copper Formate, I did several recrystallizations and got some nice monoclinic crystals.

I also produced the same monoclinic crystals using CuCO3 and adding straight Formic acid.

On heating with a methylacetylene and propadiene blow torch(1100oC) the cupric Formate evolved a whitish gas that smelled of formaldehyde and turned into a white solid. A strange red grime also formed on the sides of the test tube.



Is this Cupric Formate and if so what are some interesting uses/experiments I could use it for?

http://en.wikipedia.org/wiki/Monoclinic_crystal_system



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[*] posted on 6-12-2013 at 19:18


The blue stuff is a hydrate, presumably the tetrahydrate. According to Charles Hurd in 'The pyrolysis of carbon compounds', cupric formate decomposes at 170<sup>o</sup>C, yielding some mixture of cupric oxalate, hydrogen, elemental copper, and formaldehyde (and maybe other compounds, it's complex ... I recommend looking at the book). At your temperatures I would expect the oxalate to decompose further. Anyway, I would expect the red grime to be some combination of cuprous oxide and elemental copper...



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