I was wondering if anyone had any insight as to why the reaction of chlorosulfonic acid (colorless) and 1-dodecanol (colorless) produces a deep dark-red-colored solution? The reaction should give hydrogen lauryl sulfate, which according to this website, is a white solid.

I have also tried adding $\ce{NaCl}$ to the chlorosulfonic first, and then adding the 1-dodecanol, which surprisingly gives the sodium dodecyl sulfate soap as expected.

Is this color from over sulfonating the hydrocarbon chain on the hydrogen lauryl sulfate? If so, what would this side product be called, and why isn't it seen much in industry if it is created along with sodium dodecyl sulfate?

  • $\begingroup$ Google told me that chlorosulfonic acid reacts with tellurium to form a red solution. But that's probably not your problem unless you have very unusual contaminants in your system somewhere. My guess is that the acid (or sulfur trioxide contaminants in it) are oxidizing the dodecanol alcohol to an aldehyde or dehydrating it to an olefin, and that aldehydes/olefins are polymerizing to give you red gunk. When salt is added, is that anhydrous salt or a solution? Water in the salt could help prevent dehydration. $\endgroup$
    – Curt F.
    Jul 20, 2015 at 20:32
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    $\begingroup$ You need to provide a lot more detail otherwise any answer you get will be a guess. What is the experimental procedure in detail for both experiments (quantities, temperature, time, mode of additions etc), literature references, what stage did you get in the 1st experiment, did you do any work-up/purification, did you isolate any product(s), do you have any data for this product or products (spectroscopic etc) and so on. For example I have done chlorosulfonic acid reactions that gave a dark red color during reaction but after work-up yielded a pure white product. $\endgroup$
    – K_P
    Jul 20, 2015 at 21:59


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