Sciencemadness Discussion Board

Cleaning Sodium Copper Dichloroisocyanurate

Neuro- - 27-4-2016 at 16:45

Hello, I was wondering, as I just made the aforementioned compound from copper sulfate and sodium dichloroisocyanurate from bleach crystals if there is a way to clean the basic copper carbonate out that I believe appeared as the result of me neglecting to acidify the solution. Although I understand that it is unlikely that there are no experts on the compound (Na2[Cu(C3N3O3Cl2)4]), would there be anything I could do that could selectively make the copper carbonate soluble?

Chemist_Cup_Noodles - 28-4-2016 at 07:34

Alright so I wouldn't call myself an expert on the compound, but I've done a little reading and digging on your product here, and I've found a very relevant patent regarding the very type of complex you've formed. So I guess I'm reading from the inventor of it, who I'd say is an expert. It says in the patent that the solution must be kept acidic during production in order to keep the hydroxides from forming. Are you sure it is basic copper carbonate? I would say you should try taking a sample of it and heating it to about 290oC to test whether it is basic copper carbonate or cupric hydroxide because at this temperature, basic copper carbonate will decompose. If you see example 6 from the patent, he heats his product to about 250oC in order to see how much mass was lost, and it holds up quite well. So maybe take a sample of your precipitate, heat it to or a little above 290, and mass it afterwards. If it loses a lot of mass and changes to mostly blackish in color, it is the carbonate. If it loses only some mass and retains the majority of it's color, it should be the hydroxide.

Maybe you could clean it though by slowly adding medium strength hydrochloric acid to react with, neutralize, and dissolve the basic copper carbonate (or hydroxide). I'd say to add it a few mL at a time, stirring the solution in between additions and measuring the pH frequently.

On a related note, I don't know if you've got a very good yield because complex ions tend to form much better in acidic solutions. So you might want to try doing another reaction starting under slightly acidic conditions, and maybe use a solvent such as acetone as the inventor did.

But you mentioned that you are using bleach crystals. What specifically do you mean by this? Do you mean liquid bleach, or a dry form of pool/ drinking water sanitizer? Because I've seen a lot of various chlorinated isocyanurate pool care products that might be a good point to start from.

This is a very very interesting compound though. Could you post pictures of it if you get a good product? I'd love to see the color.

spot - 16-9-2016 at 05:08

I like the colour name given in the patent: "The color of the precipitate was Periwinkle". Not a colour I'd heard of. Lilac or Purple, yes.

The patent also mentions a complex with nickel and with cadmium. I don't have any cadmium salts on my shelf but I do have nickel chloride, and that gives a pale green crystal in contrast with copper's periwinkle powder. The photo is on 9cm filter paper, to get an idea of scale.

Neither dissolves much in water or in acetone. If anyone has a solvent suggestion I'll try recrystallizing the products.

I have cadmium bar which ought to dissolve in some strength of hydrogen chloride, in which case I'll try that too.

eta: The more I look at that photo on the left the more I reckon that's nickel hydroxide crystals. I'll have another shot at that one and check the pH. And I'll try dissolving a crystal in dilute HCl too.

Nickel dichloroisocyanurate 2 small.jpg - 133kB Copper dichloroisocyanurate small.jpg - 187kB

[Edited on 16-9-2016 by spot]

mayko - 16-9-2016 at 07:09

HCl will react with the DCCA, forming chlorine. I'd probably use dilute sulfuric or maybe acetic if I was going to try to redissolve the hydroxide/basic carbonate.