What is the difference between Sodium Lauryl Sulphate and the others?

Question

I'm wondering what the difference between Sodium Lauryl Sulphate, Sodium Laureth Sulphate and Sodium Salt of Sulphonated Laureth2? I know they are all surfactants, and can be quite harsh... I ask because I recently purchased an organic baby shampoo that specifically said "No Sodium Lauryl Sulphate" but when I read the ingredients it contains "Sodium Salt if Sulphonated Laureth2".

I purchased the product as a shampoo for sensitive skin on advice of the pharmacist and will be quite annoyed if Sodium Salt of Sulphonated Laureth2 is just another way of writing Sodium Laureth Sulphate (as I suspect it might be!!!!).

Thanks.

Answer 1

They are not identical with one another. Lauryl alcohol is:

CH3(CH2)10CH2-OH

Sodium lauryl sulfate (pardon yank spelling) is:

CH3(CH2)10CH2-OSO2O(-)Na(+)

Laureth refers to lauryl alcohol that has been treated with ethylene oxide to put a number of oxyethyl groups on the end. I think, but I do not know, that sodium salt of sulfonated laureth2 is:

CH3(CH2)10CH2-OCH2CH2O-CH2CH2-OSO2O(-) Na(+)

Laureth may or may not be the same as laureth2. If different, it will be in the number of -(OCH2CH2)-OH units.

The proof is in the pudding: Is the new product as harsh?

Answer 2

well.. Wikipedia says that the 2 in laureth-2 represents the number of ethoxy groups...  sodium laureth sulfate is really a mixture of laureth-1, laureth-2, laureth-3, laureth-4 etc.. I the laureth mixture is causing you problems i don't see why laureth-2 would be any better, but maybe its not as bad as the normal mixture.  I would look for something with non-ionic surfactants, such as Decyl glucoside, if that's possible.