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Topic: thiodiglycolic acid synthesis  (Read 2628 times)

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Offline caldwell

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thiodiglycolic acid synthesis
« on: October 18, 2010, 05:43:39 PM »
Suppose I wanted to produce thiodiglycolic acid without killing myself from the accidental production of hydrogen sulfide gas.  Would it be possible (and H2S-free) to do this by the very slow addition of monochloroacetate to an aqueous solution of sodium sulfide and then reflux it for a while? 

Thanks!

Offline caldwell

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Re: thiodiglycolic acid synthesis
« Reply #1 on: October 19, 2010, 11:33:45 PM »
Still thinking this through…

So, Na2S + H2O -> 2Na+ plus SH- plus OH-

Now when excess Cl-CH3COO:Na is added, it will (should?) react with both SH- and OH- to (eventually) produce thiodiglycolate AND diglycolate.

Since I want to avoid producing diglycolic acid in favor of thiodiglycolic acid, and Na2S is also slightly soluble in alcohols, I was thinking that I should dissolve Na2S in ethanol and then add the Cl-CH3COO:Na.  The product (thioglycolate and then thiodiglycolate) should be soluble in ethanol but at the same time the Na2S will be consumed slowly since it's only partially soluble in ethanol. 

At first glance, this seems like a better way to avoid producing H2S or unnecessary glycolate.  What do you think?

Thank you.

Offline MissPhosgene

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Re: thiodiglycolic acid synthesis
« Reply #2 on: October 20, 2010, 01:57:14 AM »
It's inexpensive: $20/25g, $31/100g from Alfa.

Big-name suppliers: TCI, Acros, Alfa

Your plan might work, but including a good trap in your set-up is worth it.

Have you searched the lit for methods?
Stereograms of the 32 crystallographic point groups: little bike wheels of cold, hard, pure rationality.

Offline caldwell

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Re: thiodiglycolic acid synthesis
« Reply #3 on: October 20, 2010, 09:03:30 AM »
Yeah, I know it's cheap to buy but my goal is complete synthesis of EDOT (3,4-ethylenedioxythiophene) from "scratch" - as a way to get my feet wet with hands-on chemistry.

Google Scholar didn't come up with much.  I did find a patent for its synthesis, but it requires 250psi of H2S - which isn't in my league. 


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