Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: Nicodemus on March 02, 2015, 08:58:30 AM
-
Hi, ;D
I've some question about Peg-40 Hydrogen Castor Oil.
I've a aqueous solution with this product and i find some free Stearic Acid in it.
First, is it possible that Stearic acid comes from PEG-40 Hydrogen Castor Oil hydrolysis?? Which kind of condition are necessary for hydrolysis reaction?
Are PEG-40 Hydrogen Castor Oil a mixture? In that case I find free acid as a pollutant?? ???
thanks!! ;D
-
Hi Nicodemus, welcome here!
It's hydrogenATED castor oil - which must saturate the double bonds, and especially transform glyceride oleate, linoleate and alpha-linoleate into stearate much beyond the <1% in the original castor oil.
Though, getting the free acid needs special conditions like an acid environment. The skin is only mildly acid. Do you detect it in ppm amounts or more abundent?
-
Thanks for reply !!
as I said before, I've a pH 4,5 solution with Peg-40 hydrogenated castor oil. Sometime this solution becomes cloudy and sometime starts to flocculate. and this is irreversible!!!! :-[ :-[ :-[
I try to investigate about this.
I think about hydroxystearic acid, because it is insoluble in water.
so, is Peg-40 hydrogenated castor oil a mixture with potential free hydroxystearic acid?
is the hydrolysis of Peg-40 hydrogenated castor oil possible in a solution with pH 4,5 and at room temperature?
lots of thanks!!!
-
Thanks to Enthalpy: I can actually Google for the correct compound. There is a NF monograph to test for the quality of hydrogenated castor oil, given in the USP: http://www.pharmacopeia.cn/v29240/usp29nf24s0_m13820.html You can execute those procedures to verify the quality of your raw material, and the vendor should be able to supply their results to you if you ask.
-
The oil (hydrogenated castor oil, a triglyceride) is not soluble in water - unless I miss something magic. Your aqueous "solution" isn't one but more probably an emulsion, like an oil-vinegar sauce or like milk.
If your sole hint is that the emulsion gets cloudy or something coalesces, my bet is that the emulsion is destabilized. Like when you add lemon juice in milk. Not due to one minority compound like some stearic acid.
Take with caution, I've limited knowledge for this. Other people here know it better.
-
Thanks a lot,
in my solution I've the Peg-40 hydrogenated castor oil, not only hydrogenated castor oil...
it's a compound use as a solubilizing in cosmetics.
-
That chemical, likewise, has a page in the USP NF: http://www.pharmacopeia.cn/v29240/usp29nf24s0_m66755.html