Here is a copy of the email exchange I had with The Beauty Brains on this topic.
I've often read that Sodium Coco Sulfate is a gentler alternative to Sodium
Lauryl Sulfate because it is derived from coconuts. I'm rather skeptical of
this claim, since Sodium Lauryl Sulfate is also derived from coconut.
I did some digging (a LOT of digging, there's almost no unbiased
information on sodium coco sulfate), and I found that the two also have the
same CAS number of 151-21-3. I'm no chemist, but I've always understood that
if the CAS number is the same, the chemical is the same.
Why are the cosmetic companies lying and trying to mislead us with sodium
coco sulfate? Is it because of the bad rap that SLS has? Or am I missing
something here about sodium coco sulfate?
The Beauty Brains:
Great question. With a little help from the CTFA's Dictionary of International Nomenclature of Cosmetic Ingredients I found the answer.
The difference is really one of purification. Coconut oil is made up of a wide range of fatty acids. They can have as few as 8 carbon atoms and as many as 20. The majority of the fatty acids are of the 12 carbon variety. That means 45-50% of coconut oil is a fatty acid containing 12 carbons.
When manufacturers make their sulfate detergents they can take pure coconut oil and run the "sulfating" reaction to produce Sodium Coco-sulfate.
However, this material doesn't foam as well and will vary depending on the quality of the coconut crops harvested that year.
Sodium Lauryl sulfate is really just a purified version of the same material. In this case they take the coconut oil and remove most of the non-12 carbon fatty acids. Their starting material is then about 80% C-12 instead of 45-50% C-12.
Ultimately, both products are primarily C-12 or Sodium Lauryl Sulfate so they get the same CAS number. However, pure SLS is more efficient and of more reliable quality so most manufacturers use this.
Very astute question. You must have some background in chemistry.
Thanks for being part of the Beauty Brains community.
The difference between SLS and Sodium Coco sulfate is no greater than the difference between purified water and unpurified water (like hard water, etc.) In terms of how it works in the hair, Sodium Coco Sulfate is just a highly, highly diluted form of SLS. If you're allergic to one, you're still gonna be allergic to the other, and such.