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Author: Subject: Dequaternization with ethanolamine

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Registered: 12-9-2021
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[*] posted on 6-10-2021 at 18:06
Dequaternization with ethanolamine

Hello - this is my first post here, let me know if it would belong better somewhere else!

I am interested in the dequaternization of ammonium salts (such as everyone's favorite trimethyltryptammonium iodide:)) to tertiary amines. This has been accomplished on simple substrates with various strong nucleophiles, such as sodium thiophenoxide[1] and DABCO[2].

These reagents are hard to get, but ethanolamine is more easily available. Hunig and Baron [3] describe dequaternization in neat ethanolamine of various species in reasonable yields (from what I can gather from Google Translate). Although I have seen this method recommended on this and other forums, I have not been able to find any amateur writeup using boiling ethanolamine.

I wonder if the success of the ethanolamine method hinges on the in-situ production of stronger nucleophiles such as piperazine and DABCO? If so, traces of water in the ethanolamine might slow down the dequaternization considerably. Yields and/or reaction times might be improved by adding molecular sieves: 1) to sequester water, and 2) since zeolites act as catalysts for the production of piperazine/DABCO from ethanolamine [4].

Does anyone here have experience using any of these nucleophiles for dequaternization? I'd love to hear it.

[1] Shamma, Tetrahedron Lett. 1966, 7(13), 1375-1379
[2] Kline, J. Med. Chem. 1982, 25 ,908-913
[3] Chem. Ber. 1957, 90(3), 403-415
[4] Patent EP0313753A2

Est-il une beauté aussi belle que le rêve ?
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[*] posted on 7-10-2021 at 10:36

If piperazine is making it work so well, it is easy to get as dewormer.
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