kazaa81 - 6-3-2005 at 13:03
Hallo to all,
I've saponified some olive oil with NaOH dissolved in water.
The resulting soap was dissolved in not much boiling water and filtered from some
not soluble and probably vegetable things.
The filtrate was allowed to cool and the soap has solidified.
I've produced this soap for obtain oleic acid from it.
The procedure was to add the soap (in this case probably much of this was Na salt of oleic acid) to warm or cold, not much difference mineral acid.
I used 30% technical grade HCl.
The soap was dissolved in boling water and the HCl added. Some fumes come out, probably of HCl. The solution was cooled and poured in a fridge.
Nothing has solidified but, oleic acid, being insoluble in water and melting at 4°C, must solidify!
The experiment was tried again by dissolving some soap in cold water and adding 30% HCl to it. The results were the same.
Why the experiment hasn't go well?
Can anyone suggest ANY info., procedure etc. please?
Please post anything which can help me.
Thanks at all for help! 
Esplosivo - 6-3-2005 at 13:54
Try reducing the volume of the solution by boiling to at lest 1/3 of the original soln and using an excess of HCl, followed by cooling. Or else useing
an excess of HCl carry out a solvent extraction with ether of chloroform (both of which are relatively easy to make). Hope this helps.
The_Davster - 6-3-2005 at 14:21
Perhaps stearic acid is one of those compounds which require being cooled sugnificantly below their melting point in order for it to solidify. Try
the freezer instead of the fridge.
bio2 - 6-3-2005 at 15:23
Fatty acids separate out as an oil layer floating to the top. Salting out and adding MeOH will help this immensely also the solution proportions are
important. Check Vogels for a procedure for making the soap and then isolating the acids without having to concentrate the mother liquor.