Copper oxychloride synthesis ?

[50AE]

I'd like to know if there is any way to synthesize copper oxychloride, and is it worth it ? I've seen blue chlorate star formulas using it, I don't know if the blues are good though.

[Miech]

It can be made by adding a dilute potassium hydroxide solution to a copper(II)chloride solution. A too strong KOH solution will turn the copper(II)chloride to CuO instantly, so carefully blend it in, preferably with a magnetic stirrer. It also works well with NaOH, but only if you like recrystalizing very much and use the product only for catalization.

 

The (simplified) reaction that occurs is as follows:

 

CuCl₂ + KOH ----> CuOCl + KCl + some impurities like KOH, CuO and CuCl₂

 

Under ideal conditions you'll need one mole KOH for every mole CuCl₂, but you'll need a slightly alkaline solution for maximum yield. Some quick calculations tell me one mole of KOH is 56 grams. When using anhydrous CuCl₂ you'll need 134.5 grams to get a stochiometric ratio, when using the dihydrate you'll need 170.5 grams.

 

Don't forget to recrystalize, potassium hydroxide contamination isn't nice when combined with metals or moisture. I don't know the best temperatures for this reaction, but I think a too hot solution will yield a mass of CuO instead of CuOCl, and a too cold one will give CuCl₂ contamination.

Edited June 1, 2009 by Miech

[FrankRizzo]

The easiest way to do it involves (2) suitable (*tall*) glass containers (pickle jars work fine), copper metal (scrap uninsulated wire is better than pieces of pipe), distilled water, hardware-store muriatic acid, regular drug-store 3% hydrogen peroxide, and if you plan to use it as a blue coloring agent, some **potassium** carbonate. The potassium carbonate is also known as "Pearl Ash", and can be purchased quite inexpensively from ceramics suppliers like Clay Art Center (find someplace close, and save on shipping). If you're using it as a whistle catalyst, you can use baking soda.

 

This is a very sloppy technique, but it works. Add the copper metal to the jar, add enough muriatic acid to cover the metal plus a bit more (~1/2" above the metal), then add a splash or two of hydrogen peroxide. **Do not use anything stronger than 3% hydrogen peroxide, or you'll end up with a foamy mess of acid and copper chloride all over your lab area.** Let it sit for about a week, until the solution has become a deep green color and your copper has dissolved as much as possible. Then, decant the solution off what's left of the copper.

 

Make a saturated solution of distilled water and potassium carbonate. *WARNING* this next step involves a reaction that will be very similar to how vinegar and baking soda react, so you need a tall container to avoid the fizzy volcano. In small additions, add this potassium carbonate solution to the copper chloride solution until it no longer fizzes. You will notice a baby blue precipitate falling to the bottom of the vessel as you add the carbonate. You'll be left with the copper oxychloride precipitate on the bottom, and a solution of KCL above. Let the precipitate settle into a nice compact layer at the bottom for a day or two, then use a turkey baster or large syringe to suck up as much of the clear solution from above the oxychloride precipitate on the bottom. Use a filter to capture the oxychloride from what's left of the KCL solution, and wash it with more distilled water. If you don't have an appropriate filter, add more distilled water to the jar, let it settle, suck up the clear layer, add more distilled water, etc. a few more times to wash as much of the KCl out of it as possible.

Edited June 1, 2009 by FrankRizzo

[Ventsi]

Frank, If baking soda is used , cant you just wash out all the sodium contaminants?

All of them would be NaCl,NaHCO3 and possibly other , but since they are all water soluble they should be removable by placing the

 

It'd be killer if I can make some copper oxyxhloride completely OTC since I cant find a source for it without having to order online.

[asilentbob]

I'm sure there is a lot of info on rec.pyrotechnics on this.

 

Ventsi, CuO is present, there is the possibility that some sodium salt will crystallize out with it and get stuck in the CuO crystal lattice. Sodium is pretty strong and messes up colors easily, best to avoid at all costs.

[FrankRizzo]

Right. There's really no way to wash all of the sodium from the material. To even get close would require many liters of distilled water, which is very wasteful. Edited June 2, 2009 by FrankRizzo

[Mumbles]

You may notice that Frank mentioned that you could use baking soda if it is to be used as a whistle catalyst, as in color production not an issue.

 

I'll try to look, but there is a way where you simply bubble air through a CuCl2 solution for a while, and it precipitates out. I'm also not sure how well recrystalization will work. In hot or boiling water, it may convert itself to the oxide. I'm also not sure if it's even soluble in hot water.

[50AE]

Thank you guys. Because I tried before knowing about the 3% H2O2 solution, I tried with 30% one and I ended with copper chloride

 

My last question is : Is it worth to synthesize copper oxychloride, when I have copper oxide. Will the oxide give a better color ?

[FrankRizzo]

Whether you use 3% hydrogen peroxide or 30% has no bearing on the end product, just the ferocity of the reaction...you want to end up with a CuCl2 solution. You add the potassium carbonate to make the oxychloride.

[WSM]

I accidently made copper oxychloride while trying to make KClO3 almost two years ago. I was using an MMO anode with a shell of niobium over a copper core. The end of the electrode was sealed with epoxy which came off and I didn't realize this happened till I saw a pale blue stain amongst the chlorate crystals . When I disassembled the cell I found the copper core was converted to copper oxychloride about an eighth inch into the electrode .

I imagine copper oxychloride could be made deliberately by setting up a "chlorate" cell with a titanium cathode and a titanium basket anode filled with copper scrap (copper wire or buss is essentially pure copper). With KCl solution (or spare mother liquor from a chlorate cell) and the proper power supplied, the copper should be converted to oxychloride over time.

I haven't gotten around to trying this yet but mean to sometime. Any thoughts?

[Mumbles]

I would be concerned about copper chlorate (explosive) contamination. It's not extremely hard to make, so I don't know if the risk is worth it.

[WSM]

Thanks Mumbles,

That thought was lingering in the back of my mind. Possibly the threat of copper chlorate formation may be somewhat mitigated by adding NH4OH, converting it to Chertier's copper (PGI article by Barry Bush). The answer may lie in whether copper oxychloride would react with ammonia. Perhaps a test to determine?

How about exposing the copper scrap to potassium hypochlorite and letting it react without "forcing" the issue with current?

Somewhere I recall copper oxychloride is formed from Cu(1)Cl (or was it Cu(2)Cl2?) exposed to O2 in the atmosphere converting to the oxychloride over time. I need to research this more.

[stormyweathers]

is oxychloride the same as hypochlorite?

[Mumbles]

Not in this case. It may look the same, but it's not. Hypochlorite is an ion, ClO-. The copper oxychloride has the oxygen and chlorine bound separately, and truely exists as a complex salt. CuCl2• 3Cu(OH)2 is one of the simpler formulas I've seen.

[50AE]

I think I successfully synthesized copper oxychloride.

 

I made a solution of copper chloride first, by mixing copper metal with HCl and H2O2.

It was let for a week outside. I took it out and I filtered out the leftovers of the copper metal.

Then I was adding slowly KOH. A baby blue colored product started to appear.

I stabilized the pH at 7.6-7.8. The color of the solution was blue-greenish. I filtered some the product and I let it dry:

[Lagrange]

copper oxychloride can be produce without any alkali hydroxide. Using Cu2o produce electrolytically (electrolyse of copper in potassium chloride). once washed the cu2o is muxed with HCL to form white cucl. the mixture is then mixed (bubbled trough) with air/oxygen to form 1 oxychloride and 1 cucl2.

 

here's the reaction formula

6 CuCl + 3/2 O₂ + 3 H₂O → 2 Cu₃Cl₂(OH)₄ + CuCl₂

Edited March 3, 2010 by Lagrange

[azure]

The most convenient preparation that works for me (no acid,alkali or peroxide needed) is to carefully add a solution of copper sulfate in water to a solution of calcium chloride in water until no more precepitation forms.

Then i bubble air through the resulting green suspension while stirring, using a small aquarium pump and a piece of tubing with a connected bubble stone.

The next day i remove the air hose and collect the light blue precepitate by means of vacuum filtration and wash the filtered solids with cold water.

 

While drying, the color of this very fine powder changes from light blue to light green to greyish/brown/white.

 

Anyway, the endproduct works very well in whistle compositions!

[WSM]

The most convenient preparation that works for me (no acid,alkali or peroxide needed) is to carefully add a solution of copper sulfate in water to a solution of calcium chloride in water until no more precepitation forms.

Then i bubble air through the resulting green suspension while stirring, using a small aquarium pump and a piece of tubing with a connected bubble stone.

The next day i remove the air hose and collect the light blue precepitate by means of vacuum filtration and wash the filtered solids with cold water.

 

While drying, the color of this very fine powder changes from light blue to light green to greyish/brown/white.

 

Anyway, the endproduct works very well in whistle compositions!

 

Hi Azure,

 

Wow! for a minute I was getting excited about a simple process to produce copper oxychloride using materials completely available from a big box hardware store. Then I realized both products (copper chloride and calcium sulfate) could precipitate out together. Separating them wouldn't be trivial. Using them for a burn rate catalyst shouldn't be a problem but trying to use such a product for a blue flame or star would be a huge challenge (unless a pale pinkish violet color is the goal, but then why make a special compound just for that?).

 

On the other hand, if you use potassium chloride instead of calcium chloride, the potassium sulfate should remain dissolved as the copper salt precipitates, or at least be less of a problem as a minor contaminant of the copper compound (for blue color production, I mean). This has possibilities; I may have to try it out (Great!, another project, the wife isn't going to like this). Now where did I stash that aquarium pump?

 

WSM

[azure]

Jep the calcium sulfate coprecipitates with the copper chloride.

When decomposing the powder in a flame you can see the 2 bands , the orange calcium band and the blue copper band.

 

But for a whistle catalyst this simple procedure can't be beaten!

Edited July 18, 2010 by azure

[Mumbles]

Dissolving the resulting product in HCl should preferentially dissolve the CuCl2 as a green solution of [CuCl4]2- ions. The copper chlorine should be soluble in water anyway. Some washing and filtering should get rid of the CaSO4.

[FrankRizzo]

During the CuSO4 + CaCl2 reaction, wouldn't the CuCl2 stay in solution? You should be able to let the CaSO4 precipitate settle to the bottom of the container, then decant or siphon off the CuCl2 soln. You could then bubble your air trough the CuCl2 soln like normal, but lose much of the calcium contamination.

 

Alternatively, you can add potassium carbonate to the CuCl2 soln until it stops fizzing, precipitate the copper oxychloride, and wash off the KCl contamination. That would skip the days of air bubbling, but it might be difficult to find the potassium carbonate OTC.

Edited July 20, 2010 by FrankRizzo

[Mumbles]

Potassium Carbonate can be found as a fertilizer as "potash" or "pearl ash". I've heard it can be extracted from wood ashes with some work. I wouldn't trust it, and just purchase it though. It's cheap and sold for making soap.

 

Do you think you could give any more info about the CuCl2 + carbonate reaction giving copper oxychloride? I would think it might precipitate the copper as copper carbonate. Does it rely on the protonation of carbonate (making OH-) or something like that? I'd think that KOH would be an easier material if that is the case.

[FrankRizzo]

Mumbles,

 

The way I've always made oxychloride is to start with scrap copper, HCl, and hydrogen peroxide. The peroxide catalyzes the HCl/Cu reaction, leaving copper chloride in solution. I then add potassium carbonate solution until the fizzing stops. The CO2 leaving the solution seems to push the reaction to the right. An excess of HCl might be necessary to keep the CuCl from becoming CuCO3 as the potassium carbonate is added.

[Mumbles]

Got it. I thought you were referring to starting from the solution resulting from the CaCl2/CuSO4 reaction.

 

Just to clarify, the final solution from the HCl/H2O2/Cu metal reaction is green, not blue, right? That would make a difference, and makes sense how it works somewhat.

[FrankRizzo]

Got it. I thought you were referring to starting from the solution resulting from the CaCl2/CuSO4 reaction.

 

Just to clarify, the final solution from the HCl/H2O2/Cu metal reaction is green, not blue, right? That would make a difference, and makes sense how it works somewhat.

 

I was figuring that the chemistry was much the same, in that you end-up with a solution of copper chloride with both reactions. However, I neglected to think of the excess H+ that is probably present with the way I do it versus the CaCl2/CuSO4 prep. Yes, the solution is very dark green. If a bit of hydrogen peroxide is added, the solution becomes dark blue.