[science2000]

Has anyone here created metal salts of fatty acids? Are they stable, interesting, water soluble?

[Yggdrasil]

Sodium and potassium salts of fatty acids have been made for ages and are common household items.  They are more commonly known as soap.

[Alberto_Kravina]

Has anyone here created metal salts of fatty acids? Are they stable, interesting, water soluble?

I tried to make a fatty acid salt with normal oil and solid NaOH in a pot some time ago. The end product was a grey cheese-like substance.

[Borek]

Hard water? What you described sounds like calcium or magnesium salt precipitate.

But then sodium salts must have limited solubility too.

[Alberto_Kravina]

Hard water? What you described sounds like calcium or magnesium salt precipitate.

I know, I know...that was kind of confusing me...the pot was clean and the reaction was made in absence of water...  
After I performed this "synthesis" I dissolved the substance in water and analyzed the sample if there were any Calcium or Magnesium cations....but nothing!

[Borek]

Well, if there was no watewr how do you want the resulting salt to be dissolved

Besides - there is no way to hydrolize fat without water. Strong base catalyse the reaction and removes acid moving equilibrium to the right, but hydrolyzis is a reaction of fat with water.

[Alberto_Kravina]

Hmm...I'll try to make the same thing with KOH today, I think that it will work better, also, I'll make the reaction at 40-50 Celsius dgrs. Do you guys have any idea of what I should add to the salt to make it look like/smell like "normal" soap?

[Borek]

Take a look here:

http://www.google.com/search?rls=en&q=making+soap+site:cavemanchemistry.com&num=25&ie=utf-8&oe=utf-8

Perhaps it will help.

[Alberto_Kravina]

hehe....Google is the solution to all our problems...

Well, I'll tell you the results as soon as I have finished the synthesis (I started five minutes ago   )

[Yggdrasil]

Making fatty acids salts from vegetable oil may produce a different product than making soaps because soaps are made from the hydrolysis of animal fat, which has a different composition than vegetable oil.  Vegetable oils have more unsaturated fatty acid chains than animal fat, so the resulting salts will have different properties.

[Alberto_Kravina]

This time it worked! The product was a soap-like white substance.  

[science2000]

I'm still unsure what it is about fatty acid soaps that kills the germs on our hands. Does anyone know?

[pantone159]

I'm still unsure what it is about fatty acid soaps that kills the germs on our hands.

Nothing, actually.  They allow the layer of oil on our hands, which contains said germs, to be washed away, thus removing the germs.

[qlabel]

I also want to try this synthesis! It´s cool! Which oil should I use?

[Alberto_Kravina]

I also want to try this synthesis! It´s cool! Which oil should I use?

Try with any commercial oil. I tried it with olive oil and penut oil and it worked. Also, try with NaOH and KOH (If you can).