[Homeslice]

I am trying to figure out how to make free form fatty acids from triglycerides.  Say extracting gamma linolenic acid from evening primrose oil. 

I think the first step is to cleave the glycerol molecule from the fatty acids.  I think in soap making they do just this by mixing the triglycerides with sodium hydroxide (lye) or potassium hydroxide.  But I think that leaves either a Na or K attached to the fatty acids, so they are still not in their free form. 

Any ideas how to make the completely free fatty acids?  And then how I might extract particular ones from the "mix"?

Thanks for any ideas!!!

[Orcio_87]

Did you heard about a neutralisation reaction ? Stronger acid replaces weaker in its salt.

Sodium or potassium salt + strong acid ---> sodium or potassium salt + fatty acid

Fatty acids, in general, are insoluble in the water.

[rolnor]

These are well-studied processes, check litarature:
https://en.m.wikipedia.org/wiki/Gamma-Linolenic_acid

[Homeslice]

Did you heard about a neutralisation reaction ? Stronger acid replaces weaker in its salt.

Sodium or potassium salt + strong acid ---> sodium or potassium salt + fatty acid

Fatty acids, in general, are insoluble in the water.

Thanks Orcio_Dojek!  I've been doing as much reading as I can.  It seems like maybe if I introduce Hydrochloric acid to the my sodium/potassium salt it would do just what you said - the HCA would replace the fatty acids, binding to the sodium/potassium, and the fatty acids would then be free.  But I cannot find anything that talks about how much HCA to add to X amount of sodium/potassium fatty acid soap, how to separate the components when the reaction is complete, etc.  Any ideas?  Again, I am not a chemist by any stretch, so this is all very new to me.

Thanks!!!

[Homeslice]

These are well-studied processes, check litarature:
https://en.m.wikipedia.org/wiki/Gamma-Linolenic_acid

I am sure it is, but everything I can find is very much greek to me.  Nothing I have seen really tells me exactly what to do, how much of what to use, etc. etc., and least in a way I can understand it.  Thanks!

[Orcio_87]

@Homeslice How much HCl - you can calculate from the reaction equation.

If you don't want to calculate - add HCl until pH will drop to about 3 - 5 (you need to have some indicator).

How to separate - pour out water above the acid and let the acid to dry.

[Homeslice]

@Homeslice How much HCl - you can calculate from the reaction equation.

If you don't want to calculate - add HCl until pH will drop to about 3 - 5 (you need to have some indicator).

How to separate - pour out water above the acid and let the acid to dry.

Thank you Orcio_Dojek!!!

What "reaction equation" might you be referring to?  Sorry again, this is all new to me, no chemistry background. 

And I certainly have a PH meter, can add HCl until the PH gets to 3ish or so.  But when you say "pour out water above the acid and let the acid to dry", let's see, seems to me there might be 4 things in the mix:

1.  Free fatty acids

2.  Water

3.  Whatever happened with the Cl from the HCl and the Na (or K) that was joined with the fatty acids previously

4.  Any HCl that was in excess of that was required and which is thus still HCl.

So when you say pour out water above the acid and let the acid to dry, how to the above 4 things (if I am right) fit into that? 

Thanks so much!!!

[Orcio_87]

Reaction is the:

Sodium or potassium salt + HCl ---> NaCl or KCl + fatty acid

After pouring out the water, you will have fatty acids in the baker and the rest (water with NaCl or KCl + HCl) in the sewers.

[Homeslice]

Reaction is the:

Sodium or potassium salt + HCl ---> NaCl or KCl + fatty acid

After pouring out the water, you will have fatty acids in the baker and the rest (water with NaCl or KCl + HCl) in the sewers.

Thank you Orcio_Dojek!  Two more questions:

1.  For the reaction, is there a place that summarizes how to do the calculation to show how much HCl I should add more or less?

2.  You mention in the beaker after the reaction is done I will have 2 layers, one being fatty acids and the other being water and all the other stuff.  Will the layers look clearly different so I can tell one from the other?  It sounds like the water layer should be on top so I just pour that out.  And the rest is basically the pure fatty acids. 

That sounds very easy, but I'm still going to take pictures as I go through it and post them here for your advice and input!   

Thanks so much!!!

[Orcio_87]

1. Yes, type "chemistry stoichiometry" in the browser and open any page.

2.

It sounds like the water layer should be on top so I just pour that out.

No.... fatty acids are less dense than water so they will float on the top.

You can pour out all of this through the filter.

[Homeslice]

Thanks Orcio_Dojek!  I see chemistry stoichiometry calculators just like you mentioned, like one here:

http://mmsphyschem.com/stoichiometry.htm

I will study that and see if I can figure it out!

So the fatty acids will float on top, everything else below.  You mention pouring everything through "the filter" - what kind of filter are you referring to? 

Thanks!

[Orcio_87]

Filter is made from the paper and have about 10 cm diameter and 0,2 mm thickness. Filter requires the use of the funnel.

[Homeslice]

Ohhh just a standard paper filter it sounds like!   

OK, so I would pour the entire solution through a funnel with a paper filter.  That will get rid of the solids in the mixture. 

But the liquid that goes through the filter, it still has at a minimum water and the free fatty acids right?  At that point the free fatty acids are floating on top of the water, and presumably have a different color (although I'm not sure about that) so I can just pour out the free fatty acids.  But what if they don't have a different color, how can I separate the two? 

Thanks!

[Homeslice]

Paging Orcio_Dojek!!!!   


So I made the soap, then added a ton of HCL to some.  Pics below.  It is very slow doing anything.  I assume it will eventually combine and there will be a layer on top (the fatty acids) and a layer beneath (the NaCl, water, and any acid left over).  But it is slow going.  How to speed it up?  Blend with a stick blender (can it take the very low PH)?  Stir with a plastic ladle?  Heat on a heating pad? 

Thank you Orcio_Dojek!!!

[Homeslice]

This is the soap, made with pure canola oil.  This was right after I poured in into my McDonald's cup container after making it, still warm.  It hardened up a good bit in the days since.