Sciencemadness Discussion Board

Disolving metals in non-polar solvent

Methyl.Magic - 25-11-2009 at 05:45

Hello,

I'd like to dissolve some metal ions such as the copper on in non-polar solvents such as liquid paraffine. Is it possible ?

I've thought abut crown ethers but they're a little expensive. Perhaps some long chain 1,2-diamine would complex the copper to dissolve in the solvent... I've recently heard of RAPOX complex "resacetophenone oxime", do you have more information about that?

Thanks in advance.

Bye.

MeFSO4.

gsd - 25-11-2009 at 06:11

Copper salts of Branch chain fatty acids (such as neodecanoic acid) or acyclic fatty acids (such as Naphthenic acid) or unsaturated fatty acids (such as oleic acid) are soluble in non polar solvents.

gsd

Methyl.Magic - 25-11-2009 at 06:30

ok I'll try with copper stearate.

gsd - 25-11-2009 at 06:45

@methyl magic

Copper Stearate may not work as it is a SATURATED acid.

However in my experience mixed acid saits (i.e. oleic + stearic etc) have good solubility.

If you can't get unsaturated FA then you can try making Na or K salts of mixed fatty acids by splitting vegetable oils. The alkali metal salts of these mixed FA can be directly used for making copper salts by "Double Decomposition" method.

gsd

Methyl.Magic - 25-11-2009 at 06:54

I didn't really understand why unsaturated FA salts are soluble and not the saturated ones ??? They've both a non polar long chain, no ?

gsd - 25-11-2009 at 07:13

Quote: Originally posted by Methyl.Magic  
I didn't really understand why unsaturated FA salts are soluble and not the saturated ones ???


Unfortunately I can't answer that but believe me that is the way it is :(

Even in case of branched chain FA, the most widely used one is 2-ethyl hexanoic acid. It produces excellently soluble metal soaps of almost all metals..... except Copper. The copper salt of 2-ethyl hexanoic acid has got practically nil solubility in petroleum solvents.

gsd

bbartlog - 25-11-2009 at 07:37

It's not easy to see the rhyme or reason to solubility; there are general rules (polar and nonpolar, plus general tendencies of particular anions and cations), but there often seem to be exceptions.
I think your request is underspecified; do you want Cu(I) or Cu(II) dissolved? How much? Two possibilities are
CuCl + AlCl3 in benzene/toluene (the CuAlCl4 apparently is soluble), or copper hexaamine complexes in anhydrous ammonia. But depending on what you're trying to do and/or your equipment these might not be good answers for you.

Methyl.Magic - 25-11-2009 at 12:15

This is for a friend who love spitting fire. He ask me how to make colored flammes. I said dissolving metals into liquid paraffine (it's what he uses) makes your flamme colored. But there are a few problems :

- The metal cation must be soluble in the very non-polar paraffine.

- The paraffine mixture must be non-toxic (wow lead gives a beautiful blue flamme ! )

I don't have to disolve much Cu(II) to get a green flamme. Perhaps I can replace it with something like trimethyl borate ? For the first test I'll try with lithium or potassium salts.

I have a relatively good equipement, but I don't really want to work with anhydrous ammonia...

thanks

MeFSO3

bbartlog - 25-11-2009 at 12:58

Paraffin of the 'liquid at room temperature' sort (i.e. what we in the US might call mineral oil? Or is this more like kerosene? I'm sure it's not paraffin wax...).

Non-toxic: well that eliminates the ideas I mentioned.

Copper isn't exactly good for you (in more than trace amounts), but I suppose if he doesn't swallow the mixture and the concentration is not high it'll be OK.

I'm thinking solubility may not be that big a deal if you can form a fine suspension/emulsion. In pyrotechnics, copper salicylate is used to get a blue flame; that would be one thing to try. Strontium compounds (e.g. strontium chloride) would also be tempting. In general I think I'd lean towards trying to make compounds known to be non-toxic work (somehow) rather than finding compounds known to be soluble but of unknown biological action. There may well be some compound that could be added to the paraffine that would allow for mutual solubility - though then you'd have to be wary of changing the flash point too much; most of the things I can think of (acetone, ethanol...) seem too dangerous, though I don't know what effect of adding say 5% of such a solvent to the paraffin would be.



not_important - 25-11-2009 at 17:34

I think an important point has been made and needs to be reiterated - most of the metals that give good flame colour are somewhat toxic, toxic enough that you'd not want to be in repeated contact with them in from the drops of paraffin, or inhaling or contact with the combustion products.

Out of the metals that give colours, only sodium, potassium, and calcium are of low toxicty. Lithium is borderline, as are borates; borate esters such as trimethyl borate hydrolyse very quickly, releasing the alcohol and forming boric acid.

The fairly strong luminosity of paraffin flames will mostly if not entirely mask the potassium colour. That leaves sodium and calcium as the remaining safe ones, and it might be difficult to get those two to appear very different.

halogenstruck - 29-11-2009 at 17:05

maybe copper acetylacetonate,volatile and soluble in non-polar solvents.
in flame it breaks into cu powder which melts into metal then deposites on wick

[Edited on 30-11-2009 by halogenstruck]

[Edited on 30-11-2009 by halogenstruck]

Methyl.Magic - 30-11-2009 at 05:09

Quote: Originally posted by bbartlog  
Paraffin of the 'liquid at room temperature' sort (i.e. what we in the US might call mineral oil? Or is this more like kerosene? I'm sure it's not paraffin wax...).

Copper isn't exactly good for you (in more than trace amounts), but I suppose if he doesn't swallow the mixture and the concentration is not high it'll be OK.

I'm thinking solubility may not be that big a deal if you can form a fine suspension/emulsion. In pyrotechnics, copper salicylate is used to get a blue flame; that would be one thing to try. Strontium compounds (e.g. strontium chloride) would also be tempting. In general I think I'd lean towards trying to make compounds known to be non-toxic work (somehow) rather than finding compounds known to be soluble but of unknown biological action. There may well be some compound that could be added to the paraffine that would allow for mutual solubility - though then you'd have to be wary of changing the flash point too much; most of the things I can think of (acetone, ethanol...) seem too dangerous, though I don't know what effect of adding say 5% of such a solvent to the paraffin would be.


Oh sorry, I was talking about "liquid paraffine" not parrafine. Liquid parrafin is an oily liquid used in kitchen burners. it's something between parrafin and kerosene...

Yes I know copper is not good for the body, but if I only use low concentration I don't think copper will dissolve in the muquous membrane. After each spit, the mouth is washed with olive oil.

Concerning the Lithium, its medical dose range from 600 to 2400 mg per day (for LiCO3) ! In my opinion, absorbing few mg of Li+ won't make any difference. like you said, the concentration is low and the liquid is not absorbed. I'll do my fisrt experience with lithium 2-ethylhexanoate.
Quote:

maybe copper acetylacetonate,volatile and soluble in non-polar solvents. in flame it breaks into cu powder which melts into metal then deposites on wick



That's very interesting way to solubilise Cu(II). How do you prepare this complexe ? Cu+2 and NH3 --> tetraaminecopper complexe, then acetylactone to form the Cu(acac)2.

HydroCarbon - 30-11-2009 at 20:19

Use ethanol as the solvent, its flammable and is polar enough to dissolve small amounts of many salts.

By the way, it seems like a horrible idea to put this kind of stuff in your mouth.

[Edited on 1-12-2009 by HydroCarbon]

halogenstruck - 30-11-2009 at 20:30

as i remember just by dissolve copper sulfate in water then adding acetylacetone then adding to the solution sodium carbonate solution.better to double check it.
i can`t see any health hazard for using Cu/Li/,....
just keep away mercury/lead/Be!!!

pantone159 - 1-12-2009 at 05:56

Quote: Originally posted by not_important  
Out of the metals that give colours, only sodium, potassium, and calcium are of low toxicty.

I thought that strontium had low toxicity, am I wrong about that?

not_important - 1-12-2009 at 09:45

It looks as if they reduced the toxicity rating over the years, SrCl2.6H2O LD-50 is now given as over 2g/kg in rats; not particularly toxic. Back when it was considered about twice as toxic as barium, ten times more toxic than that current rating.

A lot of MSDS and similar data sheets that I found list strontium compounds' toxicity often is worded so that 'no information' on the toxicity can be read as 'non-toxic', even though there is an important difference; I found several thallium compounds with similar 'no information' tags.



[Edited on 1-12-2009 by not_important]

JohnWW - 4-12-2009 at 08:03

The metallic salts of carboxylic acids that have large anions are called "soaps", having one end (the carboxylate group) that is hydrophilic, while the rest is hydrophobic (although soluble on organic liquids). One particular class of such carboxylic acids are the "naphthenic acids", derived from the "naphtha" (substituted hydrogenated naphthalenes, and other hydrocarbons of similar molecular weight, C10 and somewhat higher) obtained in petroleum refining. These are oxidized to convert them to carboxylic acids, and their Cu and Zn salts are made by precipitation from aqueous solutions of the sulfates or chlorides for use as paint-on or immersion wood and textile preservatives, a common brand-name sold in building supplies stores being "Metallex". Also, Co naphthenate is made for use as a catalyst of polyester formation in the manufacture of GRP articles.

I am rather surprised that Sr salts should be any more toxic than Ca salts, because Sr is metabolized in the body in the same way as Ca and to a lesser extent Mg. It can to a large extent substitute for the much more common Ca in bones. In this connection, fission nuclear reactions, as in atomic bombs and power stations, usually result in asymmetric splitting of heavy nuclei, with one portion being elements, including moderately long-lived radioactive isotopes, around Sr and Rb and Br, and the other portion being elements around Ba and Cs and I. This has resulted in atomic bomb tests causing radioactive Sr-90 being widely incorporated into bones in trace amounts.

[Edited on 4-12-09 by JohnWW]

[Edited on 4-12-09 by JohnWW]

gsd - 4-12-2009 at 08:49

Quote: Originally posted by JohnWW  
The metallic salts of carboxylic acids that have large anions are called "soaps", having one end (the carboxylate group) that is hydrophilic, while the rest is hydrophobic (although soluble on organic liquids). One particular class of such carboxylic acids are the "naphthenic acids", derived from the "naphtha" (substituted hydrogenated naphthalenes) obtained in petroleum refining. These are oxidized to convert them to carboxylic acids, ..........


Naphthenic Acids are the acyclic acids present in some crudes as such and are separated and recovered during crude refining. Structurally they are acyclic carboxylic acids having acid value ranging from about 150 to upto 250; the range of 210 to 230 is more common - corresponding to the average molecular weight of about 265 to 245. Their salts have good solubility in all sorts of solvents and hence find extensive application in industry.

After the commerciallization of oxo process, synthetic branched chain fatty acids such as 2-ethyl hexanoic acid, 2,2 dimethyl hexanoic acid, 2,2 diethyl hexanoic acid (neodecanoic acid) are available in very pure form and at reasonable prices so they have mostly replaced naphthenic acids. However use of copper and zinc naphthenate as wood preservative has remained very high as it is believed that the naphthenic acid radical also plays important role in their effectiveness which other carboxylic or fatty acids lack.

gsd

watson.fawkes - 4-12-2009 at 15:48

Quote: Originally posted by JohnWW  
I am rather surprised that Sr salts should be any more toxic than Ca salts
Calcium ions are a signaling ion, most notably for muscle contraction. The different size of the Sr ion would most certainly move a whole lot of homeostatic fixed point around their parameter stress, at the very least causing stress reactions.

ScienceSquirrel - 11-12-2009 at 07:45

Strontium salts, particularly the chloride are used at quite high concentrations in toothpastes for treating sensitive teeth so I would say that its toxicity is rated as pretty low.