kazaa81
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Extraction of palmitic, oleic etc. acids from olives oil
Hallo to all,
does anyone know a procedure to extract fatty acids like oleic and palmitic from olive oil?
Thanks for help! 
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Esplosivo
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Oleic acid solidifies and precipitates from the oil at low temperatures. Just place the olive oil in the fridge, and after a while a white ppt will be
present. This is a mixture of fatty acids which can be filtered out, mostly being oleic acid.
Theory guides, experiment decides.
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kazaa81
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Thanks!
Thanks very much,
Esplosivo, for the useful info.!
Ok, this is a method...
I was thinking to add 30% HCl to olive oil to get the acids from their salts in oil...probably I'm wrong......
Any idea about interchanges from acid-to-acid? Example...palmitic to caprylic (also sayed octanoic) etc.
Please maintain live this theard with any idea, not only ask-answer.
Thanx at all for help. 
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guy
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| Quote: |
Oleic acid solidifies and precipitates from the oil at low temperatures. Just place the olive oil in the fridge, and after a while a white ppt will be
present. This is a mixture of fatty acids which can be filtered out, mostly being oleic acid.
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Will ths also leave behind pure glycerin?
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neutrino
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Vegetable oils are not made of simple acids. They are usually made mostly of mono-, di- and tri- glycerides (esters of glycerin and one, two, or three
organic acid molecules, respectively) with small amounts of free acids. Cooling would probably not reduce the solubility of the free acids enough to
get them out of solution. A hydrolysis reaction might, but then you’d have to somehow separate the glycerin and the acids, leaving enough water
behind to hydrolysize the rest of the oil.
| Quote: | Originally posted by kazaa81
I was thinking to add 30% HCl to olive oil to get the acids from their salts in oil... |
You meant to add a base right? This would give you soap and glycerin, which could then probably be separated (I’m no expert in soap making, so I’m
not sure how).
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Mr. Wizard
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Couldn't you make soap with the oil of your choice, by boiling it with an excess of Sodium Hydroxide? You then take the soap and allow it to
separate from the water glycerine solution and then liberate the (stearic, palmitic, oleic ) acid by treating with a stronger acid, such as HCl or
Sulfuric. This should be fairly easy to separate, as they are not very soluble in cold water. You might try a cheaper method of making the soap by
using slaked masonry lime water and the vegetable oil, which leaves an insoluble calcium soap and a glycerine water solution. Calcium soap is usually
an unwanted byproduct of hard water and forms an insoluble scum. Treatment of this calcium soap with Hydrochloric Acid might yield the desired oil
acid and soluble calcium chloride, all with cheap materials.
If the lime and water doesn't make soap with the oil, you could first form a sodium hydroxide solution by mixing lime and sodium carbonate in
water first, heating, and letting the calcium carbonate precipitate. Exclude CO2 from the air while letting it clear. Palm and Olive oils were used in
the original PalmOlive Soap, and the reaction was supposed to be vigorous enough to not require external heating!
Most automotive greases are a mixture of a metallic soap and a mineral oil. For example, Lithium grease is a Lithium soap mixed with a mineral oil.
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chemoleo
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Yes, indeed, the best way to go about this is to boil your oil with a solution of NaOH, until the insoluble layer of oil disappears. You will then get
the sodium salts of the respective fatty acids (called saponification). These may precipitate out, if they happen to be less soluble.
Of course you will also get glycerol (glycerin), which is of course soluble in H2O. No matter, you can then precipitate the acids with the correct
amount of HCl. Their solubilities, and possibly melting points, should allow you to separate long-chain from short-chain acids, or unsaturated ones
from saturated ones.
For instance, oleic acid is unsaturated, and due to Cis/Trans isomerisation on the double bonds and the lesser ability to 'crystallise' it
has a lower melting point compared to the saturated fatty acid with the same number of carbons in the chain.
Best is to look up the respective ratios of fatty acids in different types of oils, and select the one that has the greatest proportion of the fatty
acid of interest.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Esplosivo
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| Quote: | Originally posted by guy
| Quote: |
Oleic acid solidifies and precipitates from the oil at low temperatures. Just place the olive oil in the fridge, and after a while a white ppt will be
present. This is a mixture of fatty acids which can be filtered out, mostly being oleic acid.
|
Will ths also leave behind pure glycerin? |
I didn't mean that the oleic acid from the fatty acids will break up the ester bond when cooled and leave glycerine behind. I simply meant that a
certain amount of oleic acid in the free state is present in olive oil, as far as I know. This can be seperated by cooling. The 'free' oleic
acid dissolved in oil is somewhat in low concentrations though - must have slipped out of my mind 
To extract most of the FAs an alkaline hydrolysis is preferred over an acid hydrolysis I suppose, so to extract 'insoluble' soap and leave a
mixture of glycerine and the remaining alkali. Alkaline hydrolysis is usually carried out with NaOH though, and not with Ca(OH)2. The Ca salt of the
FA would be highly insoluble in water (usually known as scum, left about by the reaction of soap with Ca salts in the water), ideal for seperation.
Theory guides, experiment decides.
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Hermes_Trismegistus
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| Quote: | Originally posted by Esplosivo
Oleic acid solidifies and precipitates from the oil at low temperatures. Just place the olive oil in the fridge, and after a while a white ppt will be
present. This is a mixture of fatty acids which can be filtered out, mostly being oleic acid. |
Explosivo is right (from personal experience) however "solidify" and "precipitate" are extremely loose terms.
Olive oil in the fridger results in pale green, cloudy, oily emulsion with a viscous consistency like the semen of a egyption mummy, thick, green and
gooey.
Some kind of crude centrifugation followed by decanation off the top may help.
But no matter what method you use I don't relish the difficult task ahead.
I forsee several messy filtrations with mixed results. Perhaps salting the fats out would help some?
Its also gonna be an asspain like sitting on a meatfork to get your glassware squeaky clean and dry and as well as keeping your counter grease free.
I'd recommend putting down polyethylene backed butcher paper first, or even newspapers over waxed paper before going to work. I'd also keep
the oven hot and the sink empty and wash my gear as I worked.
Arguing on the internet is like running in the special olympics; even if you win: you\'re still retarded.
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kazaa81
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Saponification...ok!
Hallo to all,
thanks very much to all who have maintained live this thread! Maintain live this one too.
I've heated the olive oil with NaOH for a while, 15 minutes, and I've get a thing like soap.
Now, because it is very tied to the beaker, I've fulled it with water and I'm waiting for the detaching of the soap-mass.
After this, how you've post, I dissolve this in strong HCl (would 30% suffice?) and then put the liquid (this is the first try) at 3-4°C (the
oleic acid solidifing point) for see if the oleic acid, for first, would crystallize.
Thanx at all! Maintain live this thread!
[Edited on 7-11-2004 by kazaa81]
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kazaa81
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Experiments...
Hallo to all,
I've saponified olive oil firstly with NaOH and today with Ca(OH)2.
The soap obtained from NaOH was put under water and then, removed water, added to 10% HCl until it was covered by HCl. Nothing seem to have dissolved.
Today, I saponified some oil with an excess Ca(OH)2.
After that, I've NOT put the soap under water, but I've taked some pieces of them and added to 30% HCl.
Bubbles has formed, due to the dissolving of residual Ca(OH)2 in HCl but, after 1hour, my soap seem to hasn't dissolved.
Must I wait other time? Tomorrow morning I will see.
Any idea, thing, attachment, sites and documents about fatty acids, saponification,experiments are welcomed.
Thanks for the collaboration. Maintain this theard live.
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Mr. Wizard
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Kazaa81, Have you heated the calcium soap with the acid to free the fatty acid? I'm not sure how fast this takes place, as it would depend on
the solubility of the Calcium soap. It may not even work with calcium soap. Certain fatty acids, such as stearic acid, from beef tallow, are non too
soluble themselves. You might have to try another solvent, or convert that oil with NaOH to a more soluble sodium soap, or use KOH and get 'soft
soap', which is almost a liquid.
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chemoleo
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I don't understand the problem so much to be honest.
Just boil the oil with a stoichiometric amount (dilute!!!) of NaOH, until (after settling) there is no top layer of unreacted oil.
The sodium salts should be soluble, shouldnt they?
Then the addition of HCl should precipitiate the respective fatty acids, and the addition of calcium salts should precipiate the calcium salts.
Admittedly I don't know whether all sodium salts are soluble, I am sure there are some that aren't - but maybe that's a good way to
start off.
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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kazaa81
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Probably mistakes.....
Hallo to all,
as previously writed, I've saponified my oil
with Ca(OH)2 until no oil appear.
I've put this Ca soap under 30% HCl for free the fatty acids combined in soap.
Well, after 1hour not one piece of this soap seem to have dissolved, I've saw only bubbles (I think of CO2 produced by unreacted Ca(OH)2).
Today, after 2 days of unwatched reaction, I've see that almost all pieces of soap (except one) have been dissolved.
I've added today some additional small drops of 30% HCl...hope that all the soap will dissolve!
For the crystallisation of oleic acid, which have solidifing point around 3-4°C, I think that the solution of acid/dissolved soap must be put in the
fridge at the previously temperature.
Thanks to all for help!
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Twospoons
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| Quote: |
OLEIC ACID, QsHaA, or C8HI7-CH:CH- [CH2]7 CO2 H, an organic acid occurring as a glyceride, triolein, in nearly all fats, and in many oilsolive,
almond, cod-liver, &c. (see OILS). It appears as a by-product in the manufacture of candles. To prepare it olive oil is saponified with potash,
and lead acetate added; the lead salts are separated, dried, and extracted with ether, which dissolves the lead oleate; the solution is then treated
with hydrochloric acid, the lead chloride filtered off, the liquid concentrated, and finally distilled under diminished pressure. Oleic acid is a
colorless, odourless solid, melting at 14 and boiling at 223 (10 mm.). On exposure it turns yellow, becoming rancid. Nitric acid oxidizes it to all
the fatty acids from acetic to capric. Nitrous acid gives the isomeric elaidic acid, C8H17-CH:CH-(CH2]7-C02H, which is crystalline and melts at 51.
Hydriodic acid reduces both oleic and elaidic acids to stearic acid.
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