Author Topic: Palladium, platinum, silver, gold  (Read 487 times)

psychexplorer

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Palladium, platinum, silver, gold
« on: January 26, 2011, 01:18:39 AM »
An excellent source of quality precious metals (particularly palladium and platinum for our catalysts) can be found in bullion products. There is a huge market for these, both OTC and online. It is completely open, high volume, and completely unwatched, at least below currency reporting thresholds independent of the metal itself. It is also the most cost effective source, by far, which is perfect for bees on a budget.

You can walk in to a coin shop, put down your cash, and walk out with multiple ounces of reagent grade material. For the extra paranoid (you won't need it), you can always mumble something about the guv'mint and inflation. Regular purchasing is not suspicious; rather, it is the textbook profile of the typical customer regularly putting his savings into precious metals every time he gets paid.

It is fairly obvious you are not a photographer when you are a photo supply's best customer for PdCl2 despite buying no other equipment, products, or impure mixtures. Let's be frank: in the closed minds of tyrants, anyone needing a lot of PdCl2 is running Wacker in bulk, especially from a photography outlet. PdCl2 is not technically watched, but we should act as if it were. Short of picking off the low hanging fruit with psuedo, RP, or I2, suspicious PdCl2 patterns would be easy to spot, if anyone were watching. Think about this one for a moment. Small amounts are probably fine, but repeat orders or lone PdCl2 sales to a new customer are textbook examples from a hypothetical turn-in-your-neighbor campaign.


Fortunately, readily available bullion products simplify our lives and save us money, for only a small time investment.

Bullion bars are a mixed bag for purity, although you should expect no less than .9995 with an assay certificate, nor will you have any trouble finding it. Bullion bars are typically sealed at the refiner and left intact, so you should expect nothing but a sealed product.

Canadian Maple Leaf coins are another excellent and popular source. Purity is as follows:

Pd: .9995
Pt: .9995
Ag: .9999
Au: .999, .9999, .99999

Maple Leafs are sealed at the Royal Canadian Mint, although quite a few of them are depackaged.

Be careful of most other bullion coins. The vast majority are alloys.

The advantage of a sealed, assayed product is obviously certainty in its quality.

One big advantage of going the bullion route is cost. Bullion products should be bought no more than a few percent above spot and easily converted to the requisite catalyst. This cuts out all of the middlemen and markups along the whole chain.

Pd and Pt have high melting points so this will be no substitute for well made formed products, like wire or electrodes.

The chlorination of Pd and Pt are relatively simple procedures so UTFSE.

Methyl Man

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Re: Palladium, platinum, silver, gold
« Reply #1 on: April 20, 2011, 10:58:15 PM »
I agree 110%.  I've given this one (PdCl2) much thought lately myself...

I originally posted a PdCl2 synth here, then thought maybe I'd better not paste in stuff that's obvious.  :-[

At any rate it would seem that as long as one has a convenient source for pure Pd metal, one is in good shape, because that reaction looks about as easy as they come. Hopefully the "handling fee" to the precious metals dealer isn't too high.
 
« Last Edit: April 20, 2011, 11:49:01 PM by Methyl Man »
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psychexplorer

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Re: Palladium, platinum, silver, gold
« Reply #2 on: April 22, 2011, 12:20:34 AM »
The synthesis is certainly straightforward, but posting it was a great idea. If it gets people to think about the availability of Pd metal, then it has done its job.

Analog hobby photography is growing rarer by the day. We can't always count on photo suppliers for our PdCl2, and as fewer photographers are buying it, there will be less cover for us.

Methyl Man

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Re: Palladium, platinum, silver, gold
« Reply #3 on: April 22, 2011, 10:59:19 PM »
Okay, I was concerned I had committed a "new-member copy-paste faux pas." I'll post again what I have on it:

---------------------------------------------
Just weigh 1g Pd, 5mL 35% HCl, and 1mL HNO3 60%

Leave it for 1 day; all Pd will dissolve or maybe a little bit remains.

Then evaporate in air till dryness. Then strongly heat at 300C for 10 min. If your raw materials are pure, then result is 99.8%.

=======================

Question

How can I make PdCl2 from Pd? I did once but I forgot. Looks like I used H2O2 and aqua regia or HCl.

Answer

Hydrogen peroxide isn't a necessary component to dissolve the palladium metal.  Glancing at Hawley's (1) the derivation is listed as "solution of palladium in aqua regia and evaporation".  Aqua regia in this case is the mixture of 1 part nitric acid (approx. 70%) with 3 or 4 parts hydrochloric acid (aprox. 38%), less concentrated solutions are also used but this is the traditional mixture in my experience.  Remember that solutions of aqua regia should be used fresh as they lose their potency over time.

Ammen's book (2) which covers the precious metals in great detail from a practical perspective does not list explicitly how to make palladium chloride but does not mention any difficulty in dissolving palladium in aqua regia.  Palladium is one of the least noble of the metals of the platinum group and will also dissolve in hot nitric and boiling sulfuric acid.

Once you have your palladium dissolved in your aqua regia it is evaporated to a small volume, then hydrochloric acid is added, the process is repeated.  This drives off the nitric acid and leaves behind the palladium chloride.  The anhydrous material is stable to 675ºC (1) so there should be no worries about decomposition of the product during evaporation.

====================================

Palladium chloride from palladium ingot recipe needed?

You may add HCl with little HNO3 to Pd. After dissolution (made quicker with
heating) destroy what left of HNO3 with either sulphamic acid or ascorbic acid.
Vaporize and heat to dispose traces of organics.

[end paste]

I was just having a private conversation with another member about the making of HNO3 from KNO3 in order to make one's own aqua regia to do this. If anyone else has tips please chime in, as this is a subject of serious interest for anyone who is going to need PdCl2 and knows it's getting risky to buy it, as you articulated.

I have to say also though, that I wonder sometimes whether some of these dealers of PdCl2 and other chems might not simply receive some of these "DEA directives" to report unusual purchases with a cynical snort and literally ignore them. That would be so cool, wouldn't it? Somewhere out there, some of them are reacting this way instead of with fearful boot-licking fealty to the feds...
« Last Edit: April 22, 2011, 11:04:04 PM by Methyl Man »
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carl_nnabis

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Re: Palladium, platinum, silver, gold
« Reply #4 on: May 25, 2012, 02:15:58 AM »
There is no need to make HNO3 from KNO3, you can also just threw a spatula potassium nitrate into hydrochloric acid containing your piece of palladium metal, I did it that way. After KNO3 addition the metal will be consumed in short time, leaving a deep red solution.
But... Has anyone a good method to seperate the remaining KNO3 out of this? I have it still mixed together since i did it, but as properly dried stuff, about seven grams, made out of 1,9g Pd-metal, so obvious how unpure it is with all these nitrate still in it.
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Wizard X

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Re: Palladium, platinum, silver, gold
« Reply #5 on: May 25, 2012, 06:29:52 AM »
There is no need to make HNO3 from KNO3, you can also just threw a spatula potassium nitrate into hydrochloric acid containing your piece of palladium metal, I did it that way. After KNO3 addition the metal will be consumed in short time, leaving a deep red solution.
But... Has anyone a good method to seperate the remaining KNO3 out of this? I have it still mixed together since i did it, but as properly dried stuff, about seven grams, made out of 1,9g Pd-metal, so obvious how unpure it is with all these nitrate still in it.

Almost pure nitric acid can be made by adding sulfuric acid to a nitrate salt, and heating the mixture with an oil bath. A condenser is used to condense the nitric acid fumes that bubble out of the solution.  2 NaNO3 + H2SO4 => 2 HNO3 + Na2SO4

KNO3 + HCl => HNO3 + KCl With excess HCl you have aqua regia.

In laboratory, nitric acid can be made from copper(II) nitrate or by reaction of approximately equal masses of a nitrate salt with 96% sulfuric acid (H2SO4), and distilling this mixture at nitric acid's boiling point of 83 °C until only a white crystalline mass, a metal sulfate, remains in the reaction vessel. The red fuming nitric acid obtained may be converted to the white nitric acid.
The dissolved NOx are readily removed using reduced pressure at room temperature (10-30 min at 200 mmHg or 27 kPa) to give white fuming nitric acid. This procedure can also be performed under reduced pressure and temperature in one step in order to produce less nitrogen dioxide gas.

leaving a deep red solution: The nitrogen dioxide (NO2) remains dissolved in the nitric acid colouring it yellow, or red at higher temperatures.

Ref: http://en.wikipedia.org/wiki/Nitric_acid#Industrial_production | http://en.wikipedia.org/wiki/Nitric_acid#Laboratory_synthesis
« Last Edit: May 25, 2012, 06:31:35 AM by Wizard X »
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fresh1

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Re: Palladium, platinum, silver, gold
« Reply #6 on: May 25, 2012, 07:27:19 AM »

Has anyone tried using the acetate?

 I posted some stuff on exactly this (buying Pd bullion/coins and converting it :D) in the 'safrole purity'  thread just yesterday!

 I didn't know this topic existed ::) (yeaah i know,, my bad :-[ )  but it's something I think IS worth putting it here as it deserves the publicity (and fresh could use the feedback :D)


  fresh is very interested in hearing of anywasp who has used HgAc, was it successful and particularly which solvent/s were used in the rxn :)

  PdAc is quite soluble in several solvents making 12hr pre-mixing unnecessary, AND would make recovery much easier (from a variety of methods to recover either as the acetate or with an alcohol to reduce it back to the metal 8)

As PdAc reduces back into Pd metal in methanol, ethanol, propanol, isopropanol, tert-butanol, and the like

suitable solvents for PdAc are

 one of these solvents or a mixture of two or more kinds of solvents selected from acetonitrile, ethyl acetate, dioxane, methanol, benzene, toluene, pyridine, tetrahydrofurane, hexane and diethyl ether.

The acetates are fairly straightforward to prepare by boiling Palladium in a concentrated nitric acid/GAA mix...that's all I know just now?

And considering Pd is around $600 oz on the market collectable coins like the the Canadian $50 coin are pure Pd (0.995%) coin at $6-700 are good value when you do the math. ;



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carl_nnabis

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Re: Palladium, platinum, silver, gold
« Reply #7 on: May 25, 2012, 06:54:47 PM »
D´oh!  Off course i meant potassium chloride, this is what is contaminating my PdCl2...
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ImAMANGUYS

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Re: Palladium, platinum, silver, gold
« Reply #8 on: June 20, 2012, 12:12:54 AM »
Would someone be kind enough to post the stoichiometric equation for such a reaction?

Wizard X

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Re: Palladium, platinum, silver, gold
« Reply #9 on: June 20, 2012, 12:41:31 AM »
Would someone be kind enough to post the stoichiometric equation for such a reaction?

Palladium(II) chloride is prepared by dissolving palladium metal in aqua regia or hydrochloric acid in the presence of chlorine. http://en.wikipedia.org/wiki/Palladium(II)_chloride

Dissolving platinum in aqua regia. http://en.wikipedia.org/wiki/Aqua_regia#Dissolving_platinum
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ImAMANGUYS

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Re: Palladium, platinum, silver, gold
« Reply #10 on: June 20, 2012, 02:03:37 AM »
The stoichiometric equation would relate the amounts, in moles, of the reaction... Pd + HCL + HNO3 = PdCl2 and what else...? I understand the reaction, i was asking because i wanted to know how much pallidium chloride would be produced from the reaction, using what amount of pallidium. For example, does anyone know how much PdCl2 one gram of Pd would generate using the aqua regia method?
« Last Edit: June 20, 2012, 02:47:05 AM by ImAMANGUYS »

akcom

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Re: Palladium, platinum, silver, gold
« Reply #11 on: June 20, 2012, 03:08:02 AM »
The reaction goes essentially to completion, giving a 1 to 1 molar ratio between palladium metal and palladium chloride.

carl_nnabis

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Re: Palladium, platinum, silver, gold
« Reply #12 on: June 20, 2012, 03:38:48 AM »
or in other words, anhydrous PdCl2 contains 59% metallic palladium, because: 1 Pd (106,42g) + 1 Cl2 (2 x 30,35g =70,9g) = 1 PdCl2 (177,31g/mol)  ;)
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atara

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Re: Palladium, platinum, silver, gold
« Reply #13 on: June 20, 2012, 03:14:32 PM »

Has anyone tried using the acetate?


I doubt it would work. If you look at the reaction mechanism for the Wacker oxidation, you'll notice that the actual oxidative species is the tetrachloropalladate (II) anion, which acetate will not form.

akcom

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Re: Palladium, platinum, silver, gold
« Reply #14 on: June 20, 2012, 05:03:37 PM »
atara, Palladium acetate has been used successfully in the wacker oxidation.  If you'd like I can post some refs.  The mechanism is not as clear cut as wikipedia makes it out to be.  Numerous studies have shown that varying the reaction conditions can dramatically change the lowest energy pathway (syn/anti oxidative addition etc).

ImAMANGUYS

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Re: Palladium, platinum, silver, gold
« Reply #15 on: June 20, 2012, 07:56:01 PM »
or in other words, anhydrous PdCl2 contains 59% metallic palladium, because: 1 Pd (106,42g) + 1 Cl2 (2 x 30,35g =70,9g) = 1 PdCl2 (177,31g/mol)  ;)

Thank you brother bee. I palm to faced myself after realizing how apparently obvious this was. Just refreshing my chem skills.

akcom

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Re: Palladium, platinum, silver, gold
« Reply #16 on: June 21, 2012, 03:48:21 AM »
Anyone familiar with organometallic methodology should immediately recognize the names Heck, Suzuki, and Negishi.  I'm surprised Buchwald and Hartwig aren't on there. 

Old paper, but its the first one I found after 2 seconds of searching
Quote
Improved method for the Wacker oxidation of cyclic and internal olefins
D. G. Miller and Danial D. M. Wayner
The Journal of Organic Chemistry 1990 55 (9), 2924-2927

salat

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Re: Palladium, platinum, silver, gold
« Reply #17 on: June 21, 2012, 03:31:14 PM »
I experimented with this a year or so ago by purchasing a lot (think there was 10 or so) of the little palladium foil vials and dissolving them in aqua regia.  Have distilled it with added HCL several times.  Haven't really been pursuing it, but since we're packing up to move, I filtered off the brown powder that was produced.  I rinsed it off the filter with acetone and bottled that.  There is just a fine layer covering the bottom of a small brown bottle.  Don't know if it is PdCl or not will have to investigate it later.  But the foil is very easy to dissolve compared to solid metal but you need a lot of it I'd imagine.  I am thinking of experimenting with depositing it onto charcoal.

(I probably shouldn't try posting in the morning - my brain doesn't show up til late afternoon)
« Last Edit: June 21, 2012, 03:37:59 PM by salat »
Salat

jon

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Re: Palladium, platinum, silver, gold
« Reply #18 on: July 02, 2012, 12:01:57 AM »
atara the acetate will work in a wacker, but it forms a different intermediate (pseudocyclic peroxy palladium species)
H2O2 decomposes forming water enol and regenerated catalyst.
it has a very high turnover rate but it has'nt been optimized yet you need t-butanol to make it work.
it's a very clean high yeilding reaction.

carbonated

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Re: Palladium, platinum, silver, gold
« Reply #19 on: April 05, 2013, 06:44:51 PM »
Very enlightening posts, this seems like a much safer way to acquire PdCl2. It's too bad palladium is trading at such high prices right now though ($730 an ounce vs. $200 less than four years ago!), as it kind of negates the financial incentives for doing this reaction.