making glyceryl stearate

bluebearbluebear Member
edited January 2014 in Requests / Opportunities
Hi,
I'm a home crafter with a background in biochem. 
I want to make glyceryl stearate at home and came across this blog post.
http://curious-soapmaker.com/glyceryl-stearate-home-made-emulsifier.html

Before anyone asks why make it when it's easy to buy.....my answer is just because. I like trying new things and miss synthetic chemistry. :) 

I was wondering if using a carboxylic acid (citric or acetic) as mentioned in the post as the catalyst was ok? Normally a fischer esterification is done with an inorganic acid. 

I have three concerns:
1. That the acid isn't strong enough
2. that the citric or acetic acid would get involved and I would end up with glyceryl citrate instead of glyceryl stearate?? I'm not sure of the solubility of glyceryl citrate in water......
3. That without spectroscopy, I wouldn't be able to tell if I had too much contamination with the di and tri stearate or even had glyceryl stearate citrate. 

Does anyone have any thoughts on this? 

Comments

  • BobzchemistBobzchemist Member, PCF student
    My organic chemistry is so very many years behind me, but I'll take a shot...

    1) Muriatic Acid (Hydrochloric Acid) is freely available at most hardware stores. If Citric or 5% Acetic (vinegar) isn't strong enough, you could try that. 

    2) Nobody sells glyceryl citrate, so I don't think the reaction goes that way.

    3) If you're not going to sell the glyceryl stearate, why worry about it? (I know, synthetic chemists get all caught up in making pure materials, but really, in cosmetic chemistry, it doesn't matter) If your Glyceryl Stearate has some di or tri stearate or even glyceryl stearate citrate mixed in, and it still functions as an emulsifier, then you just don't have to worry about it - it still works. If your reaction conditions, etc. are the same each time, you will very likely come out with the same mixture each time you run it.

    The amount of "contaminants" would only be a cause for concern if you want to sell something commercially that you've made from your glyceryl stearate - and if you're going to do that, then it would pay to spend the few hundred dollars it will cost to have your emulsifier analyzed at a contract lab.
    Robert Zonis, Sr. Formulation Chemist, Beaumont Products "All opinions and comments expressed are my own, have no relation to Beaumont Products, are fully copyrighted, and may not be used without written permission."
  • Standard Glyceryl Monostearate has around 40% of the alpha-monoglyceride and 55% diglyceride with the rest being residual glycerine, mositure,  little bit of triglyceride and even smaller amounts of the other possibilities.  Higher purity GMS is available, but these are usually purified via molecular distillation. 

    Melting point and Saponification value will probably give you a good idea of where you're at.  


  • @ bluebear, I assume you have the mix of Glyceryl Stearate and Glyceryl Citrate in the final product and probably Glyceryl Palmitate as wel,l since the commercially available Stearic Acid is a mixture of Stearic Acid and Palmitic Acid.
    I completely agree with Robert regarding his point #3.

    @Bobzchemist, re: #2 - Glyceryl Citrate is a well known emulsifier in a food Industry and available from several companies.

    @ alchemist - Yes, molecular distillation of GMS gives DMG ( Distilled Monoglycerides), which I like the most in formulation instead of regular GMS.
  • Thanks for your help everyone.

    @Bobzechemist Yeah, I know that it doesn't matter too much what I end up with if it works as an emulsifier and I like the feel. I just don't like the idea of not knowing...... 

    @alchemist I think I might do a rough calc of the SAP value, brilliant idea and so obvious. *smacks hand on forehead*

    @vitalys thanks for that, I didn't know that there is palmitic acid in it as well. 
  • @bluebear I would be so grateful if you could share the results of the experiment :) Good luck :)
  • I tried this last night and it was a big fat fail so did some more digging. Turns out that citric acid isn't strong enough and having water in the reaction doesn't really help as it's one of the products.
    To force the reaction I need the following

    • A strong acid
    • anhydrous conditions
    • a long heat
    • an excess of alcohol.  

    My next step is to try sodium bisulfate as the catalyst as it's the only strong acid I can get OTC and try the reaction under anhydrous conditions...
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