Cocoyl vs Lauryl?

AgateAgate Member
edited April 7 in General
I see a lot of surfactants which seem to exist both with a lauryl and a cocoyl tail, e.g. Coco Glucoside and Lauryl Glucoside, Sodium Lauryl Sulfate and Sodium Coco Sulfate, Sodium Cocoyl Isethionate and Sodium Lauryl Isethionate, etc.
My understanding is that Lauryl is strictly a C12 carbon chain, whereas Cocoyl means that the tails are similar to the fatty acids found in coconut oil, though they do not necessarily need to be derived from coconut.
Are there any generalizable differences between the cocoyl and lauryl versions of the same surfactant, e.g. one is milder than the other, one generally foams better than the other, ...?

Comments

  • PerryPerry Administrator, Professional Chemist
    edited April 7
    You've got it mostly right but in reality Lauryl is not strictly C12. It's just more C12 than the Coco version.  According to this standard, SLS must contain not less than 85% Lauryl.  In the cosmetic industry, I think the purity to call it SLS merely has to be 80% C12.  Which means 15 -20% of it may not be Lauryl. If derived from coconut oil this can be C8 - C18. It can also be derived from petroleum which gives better control over the final composition.

    Sodium Coco Sulfate is made from coconut oil too which contains about 45-50% C12. Like SLS the other stuff is anything from C8 to C18. 

    As far as differences, I don't have specific references to point you to except to say that it seems SCS is slightly lower in skin irritation than SLS. 
    https://www.hanser-elibrary.com/doi/abs/10.3139/113.110599

    But as far as performance, SLS has been the industry standard for years and if SCS performed better, than more companies would have adopted it. Empirically, we can conclude that SLS is more efficient, produces a more reliable foam, and cleans better. This is just my experience talking though, I don't have a research paper to point to.

  • lmoscalmosca Member
    edited April 7
    The difference between Lauryl- and Cocoyl-products is more pronounce when the surfactants are not blended and used as the only surfactant. Most consumer products are blends and the final effects and sensorials will likely be the same (or only slightly different) when replacing one for the other.
    In general, it seems that people prefer cocoyl-products because they are slightly milder on skin.
    Because lauryl-glycerides are the major component of coconut oils, then your cocoyl-surfactant will always lie pretty close to the lauryl-surfactant in therms of properties. Deviations are imparted by the relative ratio between the lauric-fraction and the capric/caprylic and palmitic/stearic/oleic fractions.

    One possible additional factor to consider is defined by the industry standards (see Perry's post). Thanks to that, you can always rely on Lauryl-surfactants to behave the same way in every formulation (including their native pH). Cocoyl-surfactants will have slightly different properties across different producers, depending on their sources of oils / manufacturing process (including their native pH, which might require different adjustment at the end of your formulation process).

    Then, there is the marketing effect of saying something is derived from Coconut, or otherwise naturally derived. 
    I think Lauric acid / Lauric alcohol are still produced largely from vegetable sources (perhaps 25-35% is produced from petrochemicals). So, if you source your Lauryl-surfactant manufacturer properly you can claim that as well.

    In my own view, the only difference here would be "how green is my surfactant?" Using Cocoyl-based, means that I didn't have to purify the Lauric fraction from the others (usually done by fractional distillation of esters or alcohols, which is an energy intensive process). But this opens up for another can of worms.

  • AgateAgate Member
    edited April 7
    Thanks to both for weighing in.
    With the cocoyl being prone to variability it makes sense to me that the more consistent lauryl is used as the industry standard.
    Since I am looking to go into a niche market where people might well dismiss a product that has "Sodium Lauryl ___" in it, I'll focus on the cocoyl and deal with the variability if no other disadvantage comes up.
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