[Corribus]

Friends:
I'm looking to manufacture a lipophilic platinum salt, like this one:

https://pubchem.ncbi.nlm.nih.gov/compound/22182901#section=Top

Any fatty acid salt with a reasonably long hydrophobic tail will do. However I haven't had much luck finding any procedures or even commercial vendors, although the compound apparently exists. Any ideas?

[wildfyr]

Anion exchange resin charged with the fatty acid salt, then add a platinum salt? Do you want Pt(II) or Pt(IV)?

The IV salts seem more soluble. PtBr₄ is a little soluble in water. It looks like chloride and bromide salts of Pt(II) are only soluble in acids and ammonia. While I couldn't find anything in a quick look, maybe the iodide has water or alcohol solubility. I wish I had a quick answer but I couldn't find a good solid alcohol soluble Pt salt at a quick glance, but if you find one then anion exchange resin should work great.

[wildfyr]

All the values I saw were at 20°C, maybe boiling (degassed) water would change the story for PtBr₂ and the like.

[Corribus]

I'm basically looking to get platinum well dispersed in a hydrophobic medium. The form of platinum doesn't really matter to me, as long as it will disperse reasonably well. This is why I was thinking fatty acid salt (e.g., like, metal stearate).

[wildfyr]

Ah. Well Pt(IV)Cl₄ is soluble in acetone and water. You could anion exchange that.

Or sigma sells Trimethyl(methylcyclopentadienyl)platinum(IV), I'm sure that's soluble on toluene.

[Babcock_Hall]

I think one might prefer to use a polysaccharide-based ion-exchange gel, not a polystyrene-based one.  I would imagine that there would be too much hydrophobic interaction with the latter.  I don't have specific experience, however.

[Corribus]

Forgive me - I've never used an ion exchange resin to do something like this before. Could you walk me through how you would do this, generally speaking?

[wildfyr]

Take some resin and add a huge excess of a concentrated solution of the fatty acid to an anion exchange resin and let it stir overnight. Filter off the resin and rinse it with clean solvent a few times. Dissolve your Pt salt in something and stir it with the resin again overnight. Collect the solution and you should have your platinum fatty acid salt. Save the resin too, it can be reused many times.

[Babcock_Hall]

The problem that I see is the solubility of the fatty acid.  Ordinarily when one converts a resin into a particular counter-ion form, one uses a 1 M solution and passes a number of column volumes through the resin in order to convert it.  The solubility of a typical fatty acid in water is not high; one might form micelles.

[wildfyr]

I think you're still orders of magnitude of concentration of monomer higher than the ions already in the resin. You should be able to see if exchange occurred by taking FTIR of the resin. Look for the carboxylate peak.

[Corribus]

Take some resin and add a huge excess of a concentrated solution of the fatty acid to an anion exchange resin and let it stir overnight. Filter off the resin and rinse it with clean solvent a few times. Dissolve your Pt salt in something and stir it with the resin again overnight. Collect the solution and you should have your platinum fatty acid salt. Save the resin too, it can be reused many times.

Sorry, I'm a little confused. I take some resin and add a huge excess of fatty acid solution (in water? in organic solvent? if the latter, does it matter which solvent?). Filter off, rinse with clean solvent (same as before?). At this point my fatty acid is bound to the resin, right? Dissolve platinum salt in something (water?). Stir over night. Collect aqueous solution and my fatty acid salt is in the water? That doesn't make much sense to me, because the fatty acid salt shouldn't be water soluble.

Next question: How fatty of an acid can I use do you think? Hexanoic acid? Stearic acid?
Next question: is there a limit to how far I can scale it up? I'd like a minimum of a few 100 mg - a gram would be better.

EDIT: I didn't read the posts after yours until after I replied. So I see the issue of solubility is already brought up. The goal is to create a fat-soluble platinum source, preferably dissolved at high concentration in a nonpolar solvent like hexane or toluene. I guess something like this: https://patents.google.com/patent/US5149854 . But man I find patents impossible to read.

[wildfyr]

Yep, your quick procedure is about correct. I prefer to do all organics because they evaporate more easily.

I would go with a smaller fatty acid, but that's just a gut check, I don't know if it matters. Smaller stuff will exchange with better kinetics usually.I would check it with IR to make sure exchange occurred.

A gram is a lot... Just from the platinum sense. It's an expensive metal. Resin is moderately priced, but very reusable.

[wildfyr]

Also for reading patent literature, I just scroll down to the examples. They are written like typical procedures. I think they have some reasonable ones in that patent.

[kriggy]

Yeah reading patents takes time and patience but that one seems pretty ok.

13.8g of platinum tetrachloride and 21.5g of sodium neodecanoate are warmed to 56° C. in 150 mL of ace tone and are stirred for 3 hrs. The slurry is filtered and acetone is evaporated from the solution. The residue is dissolved in 100 mL of xylene and insoluble material is separated by centrifuging. The remaining solids are washed with additional xylene and xylene layers are combined. The product (131.6 g) contains 6.59% platinum (88% yield).

Seems like the exact stuff you are looking for

[Babcock_Hall]

When I have exchanged counter ions using resins or gels, I more often work in column mode than in batch mode.  I am not sure that it makes a great deal of difference.