Sciencemadness Discussion Board

Solubility of Copper Salts

VeritasC&E - 20-7-2021 at 09:51


Hello everyone!

I've noticed we have a few copper compound specialists on the forum. I'm wondering if anyone has experimented enough to be able to provide me solubility data for the following copper compounds (at least water, 20C, though different temperatures would be awesome):

Copper Citrate
Copper Ascorbate
Copper Glycinate

Thank you for helping!

[Edited on 20-7-2021 by VeritasC&E]

woelen - 22-7-2021 at 00:34

I assume you are talking about copper(II) salts.

Copper(II) ascorbate is not stable. There will be an internal redox reaction in which the ascorbate ion reduces the copper(II) to copper(I). At low pH, reduction can even proceed to copper metal, albeit slowly. Copper(I) does not form a stable ascorbate salt, but forms hydrous Cu2O in aqueous solution.

Copper(II) citrate is not a simple salt, but a complex. It is more stable than copper(II) ascorbate, but in the long run, the citrate ion also reduces the copper(II) to copper(I), especially at somewhat higher pH.

I do not know about copper(II) glycinate, but I expect this to form a complex. I expect it to be fairly stable, however, in terms of redox properties. I mhave no personal experience with that though.

Bedlasky - 22-7-2021 at 02:08

Woelen: Copper(II) citrate is well known stable complex. I wouldn't be surprised if some double citrates of copper also exist (Cu(II) as part of complex anion). I also did some experiments with Cu(II) complexes in alkaline solution. I didn't test citrate, but tartrate, glycerol and sorbitol complexes are quite stable and decompose very very very slowly in to Cu2O. I think that citrate behaves similarly.

Copper(II) glycinate definitely exist, Teodor have very nice write-up about its synthesis.

Copper(II)-ascorbate actually exist. It can be prepared at certain conditions, internal redox reaction doesn't take place at such a conditions:

https://www.researchgate.net/publication/233294055_Synthesis...

VeritasC&E - 22-7-2021 at 06:32

Thank you both for the valuable information.

Has anyone hands on experience with one of these salts and be able to provide approximate solubility data?

mayko - 22-7-2021 at 06:41

Copper citrate is insoluble in water, at all temperatures as far as I know. It forms soluble complexes with solutions of ammonia or basic citrate.

teodor - 22-7-2021 at 09:55

Quote: Originally posted by Bedlasky  

Copper(II) glycinate definitely exist, Teodor have very nice write-up about its synthesis.


It was somebody else, not me. I didn't do much with copper salts especially of organic anions yet. I have some interest to cobalt salts of carboxylic acids and properties of different transitional metals acetates (anhydrous and hydrates), that's all for the moment about organic salts.

Bedlasky - 22-7-2021 at 10:05

Quote: Originally posted by teodor  
Quote: Originally posted by Bedlasky  

Copper(II) glycinate definitely exist, Teodor have very nice write-up about its synthesis.


It was somebody else, not me. I didn't do much with copper salts especially of organic anions yet. I have some interest to cobalt salts of carboxylic acids and properties of different transitional metals acetates (anhydrous and hydrates), that's all for the moment about organic salts.


Oh sorry, I thought that I read it from you. I search the topic and it was Lion850 who did this write-up. My memory is terrible :D. Sorry again. Here is the topic about copper glycinate:

https://www.sciencemadness.org/whisper/viewthread.php?tid=15...

[Edited on 22-7-2021 by Bedlasky]

teodor - 22-7-2021 at 11:09

Your memory is precious Bedlasky for anything regarding metal complexes so it should be good for other things also. You just didn't now that evaporating for dryness is not my method ;)