D4RR3N - 26-7-2010 at 03:34
Esterified fatty acids, how do you produce them? I mean I know that its the reaction of alcohol and an acid (fatty acid in this case) but is it as
simple as just adding alcohol to a fatty acid?
As a starting point lets consider Esterified Borag seed oil which is high in gamma linolenic acid (GLA). The idea being to make "free" fatty acids.
bbartlog - 26-7-2010 at 04:42
You seem a little confused. A free fatty acid is not the same thing as an ester. You have a number of different pieces here.
The seed oil at first is composed of fatty acids hanging off of glycerol. Each glycerol molecule, being a triol, has three fatty acids attached.
If you want to isolate the fatty acids, then:
The first step is to break up this triglyceride so that the fatty acids are no longer attached to the glycerol. This can be done using either acid or
base; if for example you heat the oil with lye (NaOH/KOH) you end up with glycerol and the salts of the fatty acids (aka soap, more or less).
On acidification you would have the free fatty acids (but not an ester).
Esterification could then be done using the fatty acid and whatever alcohol you had in mind, catalyzed by acid (almost always sulfuric I think, the
water withdrawn by it helps drive the reaction towards the ester).
I've omitted any mention of the workup(s) involved in all this. The reactions described proceed pretty easily. The separation of products is really
the hard part.
If on the other hand you just want to produce esters, you can do transesterification (substituting your alcohol for the glycerol) using the same
methods that are used to produce biodiesel. It's somewhat trickier than the saponification described above, but you can find instruction online.
D4RR3N - 26-7-2010 at 06:20
Thank you bbartlog!!
I'm looking to release the fatty acid in the oil so it is in its free form.
I'm not necessarily looking to then separate it from the other components. If the fatty acid is in its free form and undamaged by the process then
that should be fine.
As you said boiling the Borag oil with a base will produce soap and fatty acid salts I don't think that's what I'm looking for.
Heating the oil with an acid on the other hand could do the trick if the fatty acid is not damaged by the process.
I assume I can use any acid to do this as long as it is of a minimum ph level?
I'm thinking of heating the oil with citric acid if that would work?
I don't know how I got this confused with esterification, I think I read somewhere that it was the method used to release the fatty acids. Could it be
de-esterification?
[Edited on 26-7-2010 by D4RR3N]
aonomus - 26-7-2010 at 13:00
You need 2 steps usually when it comes to vegetable oils and fatty acids. You could try a direct hydrolysis but from experience the glycerol layer
likes to form an emulsion. If you perform a transesterification to say an ethyl or methyl ester, separate (this separates cleanly), and then hydrolyze
with an acid catalyst and distill the alcohol off to drive the reaction to completion, you can get reasonably clean free fatty acid, and you can
re-use the alcohol as needed.
D4RR3N - 26-7-2010 at 14:14
Well I have been trying to find the most simple and direct method. Whilst searching I read about how lipase is used to release the fatty acids from
palm oil. I did a quick google and found you can purchase lipase powder for cheese making quit easily. I am now thinking of this an an easier option.
As far as I understand it you just require water, lipase powder and the oil you want to hydrolyse.
Anyone have any suggestions on this?
oh and thanks for all the help!
[Edited on 26-7-2010 by D4RR3N]
zed - 27-7-2010 at 13:03
So, it's free fatty acids you are wanting? OK. But, they do tend to stink.
Usually, this is done with lye in water. The process is called saponification. http://en.wikipedia.org/wiki/Saponification
As for producing esters, usually refluxing a fatty acid with an alcohol, in the presence of an acid catalyst, will do the trick. Just distill off
water as it is formed, to drive the reaction to completion.
[Edited on 27-7-2010 by zed]