Sodium laureth sulfate

October 23, 2017
You can clean up with me.
What molecule am I?

Take a look at the list of ingredients on the label of your favorite body wash, face wash, or shampoo. More than likely, sodium laureth sulfate is the first  ingredient (after water) on the list.

But wait—“laureth” isn’t a chemical term, is it? Well, it is, sort of. It’s a contraction for “lauryl ether” in its more formal name, sodium lauryl ether sulfate, or SLES.

Lauryl, of course, is an early term for what is now called the dodecyl alkyl group, or n-C12H25. Ether refers to one or more ethylene oxide groups placed between the sulfate and lauryl moieties. So SLES is an oligomer that contains a few ethylene oxide linkages; the mean quantity is about 3, as shown in the 3-D image.

SLES is the most common of a group of commercial sodium and ammonium alkyl and alkyl ether sulfates. It is an inexpensive surfactant that foams easily and is an excellent detergent. It’s essentially a synthetic soap.

The commercial product is an aqueous solution that contains 30–70 wt% of SLES. Its properties are similar to those of its non-ether cousin, sodium lauryl sulfate (SLS). Both are used extensively in household and industrial cleaners, as well as in personal care products.

In the past few years, several postings on the Internet claimed that SLES and SLS can cause cancer. This myth has been debunked by Snopes.com and other Web sites. The surfactants’ worst adverse effect is skin irritation; and they should certainly be kept away from the eyes. 

Sodium laureth sulfate fast facts

CAS Reg. No. 9004-82-4
Molar mass 420.54 g/mol (n =3)
Formula C18H37NaO7S (n =3)
Appearance Clear to slightly hazy solution 
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