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Question #171 posted on 08/12/2003 midnight

Dear 100 Hour Board,
A quick glance at the ingredients of most shampoos yields the following two common ingredients: sodium lauryl sulfate and sodium laureth sulfate. What is the difference between them (other than the spelling)? What makes the one -yl and the other one -eth? With all this talk about chemistry recently, including the chemical formula and maybe even the structure will be helpful to me.
- long time since 105

A: Dear former student,
Sodium lauryl sulfate is C12H25SO4-Na+. Sodium laureth sulfate is (C2H4O)nC12H24SO4-Na+. The compound (lauric acid) from which these are derived was first extracted from berries of the bay or laurel tree (Laurus nobilis). The -yl ending is just a general ending for alkane groups. The -eth ending indicates the presence of at least one ether group. For your pleasure:

-short time since