Sciencemadness Discussion Board - Copper oleate: Syth and Properties

Copper oleate: Syth and Properties

numos - 31-3-2014 at 21:02

SO...

I am very near completing my copper salts collection and I am at the last few that I want to make.

Copper oleate seems like an avoided salt in that I found it difficult to find much information property-wise, other than its used as a pesticide/insecticide.

I found this:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&a...

"The Cu–oleate complex was prepared by reacting CuCl2 and sodium oleate. In a typical synthesis of Cu–oleate complex, CuCl2∙2H2O (40 mmol) and sodium oleate (80mmol) was dissolved in a mixture solvent composed of 80 ml ethanol, 60 ml distilled water and 140 ml hexane. The resulting solution was heated to 70 °C and kept at that temperature for four hours. When the reaction was completed, the upper organic layer containing the Cu–oleate complex was washed three times with 30 ml distilled water in a separatory funnel. After washing, hexane was evaporated off, resulting in Cu–oleate complex in a waxy solid form..."

But this is a rather complex reaction -- which I can do, just wondering if there is an easier way. Also instead of ethanol can I use methanol? And instead of hexane can I use heptane?

Why can't I simply add oleic acid to freshly made copper hydroxide, is it because oleic acid is such a weak acid?

[Edited on 4-1-2014 by numos]

unionised - 1-4-2014 at 05:58

You can get a crude copper oleate preparation by dissolving copper sulphate in water and adding to to a solution of sodium oleate.
The blueish greenish copper oleate precipitates as a greasy mess and can be filtered off and dried.

You can't easily react copper hydroxide with oleic acid because the reaction only happens at the surface of the copper hydroxide particles. The copper oleate coates the hydroxide and stops the reaction.

On the other hand, I'm sure that reaction scheme would work if you used methanol and heptane.

Steam - 1-4-2014 at 07:15

Couldn't you make it form copper sulfate and oleic acid? Just guessing here.

numos - 1-4-2014 at 07:47

Steam, that would be lovely but unlikely, because what would happen to the sulfate ion? I'm going to try CuSo4 and sodium oleate, am I correct in assuming sodium oleate can be made with NaOH and oleic acid?

Nicodem - 1-4-2014 at 07:53

UTFSE: Sr, Mg, and Transition Metal Soaps!

Zyklon-A - 1-4-2014 at 08:00

Quote: Originally posted by numos

Steam, that would be lovely but unlikely, because what would happen to the sulfate ion?

Well if the reaction worked, I think it would combine with the hydrogen in oleic acid to make sulfuric acid. Of course that doesn't mean that the reaction will happen, the reveres might happen though.

DraconicAcid - 1-4-2014 at 08:05

Quote: Originally posted by Zyklonb

Quote: Originally posted by numos

Steam, that would be lovely but unlikely, because what would happen to the sulfate ion?

And sulphuric acid would ruin the product.

If you reacted copper(II) acetate with oleic acid, that would be more likely to work.

numos - 1-4-2014 at 10:50

Quote: Originally posted by Nicodem

UTFSE: Sr, Mg, and Transition Metal Soaps!

I saw this thread, and made copper stearate already, is the procedure for oleate the same? They are both fatty compounds so it might be possible. However as the compound copper oleate didn't provide search results in forum, I wanted to have a clarification.

blogfast25 - 1-4-2014 at 11:44

Quote: Originally posted by numos

I saw this thread, and made copper stearate already, is the procedure for oleate the same? They are both fatty compounds so it might be possible.

They are remarkably similar: both C18, one with a cis-9 unsaturation. I don't see why what works for the stearate would not work for the oleate.

numos - 2-6-2014 at 19:20

So I finally got around doing this, and I got some interesting results. I went with the copper acetate/oleic acid approach, as suggested by DraconicAcid.

So my first surprise is Copper oleate is an oil? As soon as the oleic acid hit the solution of Copper acetate I noticed a dark blue layer appear between them. I started to stir the mixture, and did so for the next 10 min.

After the stirring there was a thick layer of deep teal colored liquid, behaved almost exactly like oil.

Then through the separatory funnel (guess how much fun that was to clean). Notice how the bottom layer is a very light blue, indicating that the Copper acetate did indeed react away.

I was left with a liquid that smelled like oleic acid and was a beautiful deep teal.

Notes:
Copper acetate solution: 0.4g Cu(CH₃COO)₂ in 20ml of water
Oleic acid: 1.5ml; Purified at <98%

Yield ~1ml

I know it's not stoichiometric, I just wanted to see if it works...

For all you Copper fans, this is definitely worth trying just to have done it once. Cleanup is hell, although acetone makes short work of it (Physical scrubbing still required)

Edit: changed color from aqua and turquoise to teal

[Edited on 6-3-2014 by numos]

Eddygp - 6-6-2014 at 13:09

That is magnificent! I will try to prepare this at home this month... I'm running short of copper lately but I'll buy some sulphate as soon as possible. Are you sure that it isn't just a copper compound in suspension in oleic acid?

numos - 6-6-2014 at 17:39

Quote: Originally posted by Eddygp

Are you sure that it isn't just a copper compound in suspension in oleic acid?

I went back to check on the vial, and the mass had solidified. It's kind of a very thick paste, you may be right. Although the color is still incredible.

Eddygp - 7-6-2014 at 04:08

Well, it should be a colloid with very small particles anyway. Try to flocculate it with FeSO₄ solution to see if it is indeed a suspension.

The Volatile Chemist - 7-6-2014 at 04:57

Quote: Originally posted by Eddygp

Well, it should be a colloid with very small particles anyway. Try to flocculate it with FeSO₄ solution to see if it is indeed a suspension.

If you have it, Alumium sulfate wworks even better for flocculating. You're sure this is no complex?