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Author: Subject: Amine alkylation catalysts
njl
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[*] posted on 8-9-2020 at 06:17
Amine alkylation catalysts


Amine alkylation is obviously an important reaction in organic chemistry, more or less accessible to the amateur via reductive amination or with alkyl halides. However, industrially this reaction is generally conducted using alcohols as alkylating agents since they are much cheaper and more available. Doing some quick searching shows that many methods for alkylation using alcohols are available on the laboratory scale, but the procedures vary widely in their choice of catalyst, ranging from copper complex's to indium halides. I'm wondering if anyone where either has any experience with these reactions on a small scale or could give any insight as to what the most accessible catalyst for the dehydration/alkylation reaction might be.
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draculic acid69
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[*] posted on 20-10-2020 at 05:03


I Think somewhere it said alcohol+amine+iron salts in a pressure vessel at 300'c or so is how it works
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njl
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[*] posted on 20-10-2020 at 05:18


That sounds about right, I read about iron 3 salts catalyzing amide formation too.
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EverythingAl2O3
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[*] posted on 2-12-2020 at 16:04


You can also use Al2O3. The example given in an old 1959 Orgo textbook is that 1eq of MeOH +NH3 over Al2O3 at 350C leads to amination of the alcohol. I know nothing about the reaction chamber but Al2O3 is pretty cheap or you can make it yourself.

[Edited on 3-12-2020 by EverythingAl2O3]
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zed
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[*] posted on 2-12-2020 at 22:09


Somewhere around here, long ago, I posted a reference to this procedure. I'll see if I can dig it up. Long pause...........

Yeah, got it, it was a while ago. 12 years. I would have thought it had only been 5 or 6.

Pretty good discussion on this topic.

https://www.sciencemadness.org/whisper/viewthread.php?tid=11...

[Edited on 3-12-2020 by zed]

[Edited on 3-12-2020 by zed]
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Opylation
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[*] posted on 3-12-2020 at 00:26


I just had to comment on how funny it is that your name is EverythingAl2O3 and your post is indeed about Al2O3

[Edited on 3-12-2020 by Opylation]
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njl
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[*] posted on 3-12-2020 at 06:56


I think we're witnessing the birth of an account that will either be very helpful or very annoying. I for one welcome the Al2O3 revolution with open arms.
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EverythingAl2O3
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[*] posted on 3-12-2020 at 07:07


I promise I am not going to try to be annoying. I have spent countless days working on theoretical reactions that Al2O3 can catalyze and found papers to support many of them. Others I can't find and will have to test myself.
Quote:

I think we're witnessing the birth of an account that will either be very helpful or very annoying. I for one welcome the Al2O3 revolution with open arms.


[Edited on 3-12-2020 by EverythingAl2O3]

[Edited on 4-12-2020 by EverythingAl2O3]
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njl
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[*] posted on 3-12-2020 at 07:28


Just kidding around :) I don't really understand how ceramics (like Al2O3, SiO2, CuO, TiO2, etc.) which all seem relatively inert can be so versatile in industry. Do you think Al2O3 and similar compounds should have a more substantial presence in amateur chemistry?
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[*] posted on 3-12-2020 at 09:09


They should.
But they are for the "advanced amateurs" because they require more advanced hardware than the usual test tubes and Erlenmeyers.
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EverythingAl2O3
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[*] posted on 3-12-2020 at 09:45


Absolutely. They are mostly non-toxic. In the case of Al2O3 it is only really a respiratory hazard. I have found papers on 8 reactions that pure Al2O3 catalyzes and many many more where it is a mixed catalyst. We are talking Aldol condensation, alkenes, ethers, amination, disproportionation of ethers (can swap ether substituents, can swap substituents with sulfides, and swap substituents with primary alkyl halides), thiols and sulfides (Used industrially for methanethiol and ethanethiol, and sulfides) . The main draw back for many of these is that you need temps of around 200C for it to work.
I found a paper that either shows a pyrolysis like reaction with esters, or it cleaves the ester and then dehydrates it. Either way an alkene and carboxylic acid formed. This makes me think that it should be able to be used in esterification, and possible anhydride synthesis. Because of the Aldol condensation it means that Al2O3 can interact with carbonyl oxygens, which also means acetal, imine and enamine formation should also be possible (and I have found a paper that shows SO4-2/Al2O3 does for acetals) I'll put as many of my references here as I can in the order I mention them.
Quote:

Just kidding around :) I don't really understand how ceramics (like Al2O3, SiO2, CuO, TiO2, etc.) which all seem relatively inert can be so versatile in industry. Do you think Al2O3 and similar compounds should have a more substantial presence in amateur chemistry?


Attachment: HIGHLY ACTIVE ALUMINA FOR ALDOL CONDENSATION 0F ACETONE.pdf (176kB)
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Attachment: Aluminum oxide alcohol.pdf (1.6MB)
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Attachment: Mechanism of Ether Formation Using Alumina Catalyst.pdf (687kB)
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Attachment: Methanol thiolation over Al2O3and WS2catalysts modified with cesium.pdf (1.6MB)
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Attachment: Product Selectivities for 2-Methylcyclohexanol Conversion with Metal Oxide Catalysts.pdf (982kB)
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