laekkerBoy
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Trimethylamine - Which catalyst?
Hi everyone!
I have decided to make some trimethylamine to be able to complete my synthesis of bis(2,4,6-trichlorophenol) Oxalate, more commonly known as TCPO,
used in glow stick reactions.
I have found a pretty easy reaction on Wikipedia, which states the following:
"Trimethylamine is prepared by the reaction of ammonia and methanol employing a catalyst:
3 CH3OH + NH3 → (CH3)3N + 3 H2O"
My question is which catalysts can be used? I was wondering if a Lewis acid such as AlCl3 would work.
The Kindest Regards,
Christian.
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mr.crow
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You probably want triethylamine, the methyl version has too low a boiling point.
If you have trichlorophenol and oxalyl chloride you can most certainly buy TEA.
The wikipedia method is for industrial scale. If you want to make it you could use ethyl chloride/bromide and ammonia. It just needs to react with the
HCl produced by the reaction so it can be a mixed product,
Good luck!
Double, double toil and trouble; Fire burn, and caldron bubble
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laekkerBoy
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Thank you very much! Very helpful.
Even though NurdRage told me that trimethylamine probably could be used, I am going to stick to the triethylamine by your advise.
Now on to the searching once again 
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laekkerBoy
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Okay, found out a bit of usefulness  .
What do you say about this idea of making ethyl chloride:
C2H5OH(aq) + HCl(aq) ==> C2H5Cl(aq) + H2O(aq)
Doing the reaction in a distilling apparatus with ice-cold water in the condenser and the receiving flask cooled down by a CaCl2 ice-batch should do
it just fine. That way, the ethyl chloride will automatically distill over without any heating. The water and any unreacted chemicals would then stay
in the reacting flask. Pretty cool I think.
If I then kept bubbling ammonia gas trough the cold ethyl chloride for a while, I should get triethylamine. Can't see why not. Can you?
NH3(g) + 3C2H5Cl(aq) ==> N(CH2CH3)3(aq) + 3HCl(g)
Thanks in advance!
[Edited on 6-5-2010 by laekkerBoy]
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DJF90
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I can see why not... because aqueous HCl doesn't react with primary alcohols to give alkyl halides, at least without ZnCl2 (or other appropriate lewis
acid). See Vogel (again, available in the forum library!) under 1-chlorobutane for method.
[Edited on 6-5-2010 by DJF90]
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rrkss
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Go with ethyl bromide instead. Much easier to make than ethyl chloride. See http://www.sciencemadness.org/talk/viewthread.php?tid=10758
You can do an alkylation of ammonia as proposed but be aware, you will get a mixture of products (primary, secondary and the desired tertiary amine)
which needs to then be separated.
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bbartlog
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| Quote: | | That way, the ethyl chloride will automatically distill over without any heating. |
You'll end up needing heat anyway to drive the reaction. Ethyl chloride will not form at an appreciable rate at room temperature. But in general, you
want at least a little heat even when distilling low-boiling fluids. Using the heat that passes into the container just from room temperature air will
make for a very slow process unless it's liquid chlorine or something that you're vaporizing.
The Vogel prep is a little sketchy IMO, it has more water than you want (from the water in the HCl solution). When I tried something similar for
isopropyl chloride I only got 40something% yield. If you can manage it you will do better with dry, gaseous HCl piped in, or else you can try to add
the HCl to the ethanol and then dry it somehow before adding ZnCl2 and heat.
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Nicodem
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Trimethylamine can be made by the Leuckart-Wallach methylation of ammonium formate. Essentially, you heat on a steam bath a mixture of 25% ammonia and
paraformaldehyde (or formaldehyde) in 85% formic acid untill no more CO2 bubbles form (Caution and cooling while adding ammonia to 85% HCOOH! Very
exothermic!). Rotavaping the reaction mixture gives you the crude formate from which you get trimethylamine gas by neutralization with NaOH(aq). Check
the literature for details.
The Leuckart-Wallach methylation gives tertiary amines as the end products even if the HCHO vs. amine ratio is not proper, so the more readily
available hexamine should be able to substitute ammonia and paraformaldehyde.
LaekkerBoy, please keep beginners topics in the Beginners section! You are not new here any more and you were already told this previously. Besides,
what is all this about bis(2,4,6-trichlorophenol) oxalate? If you are not able to even search the literature (Do you seriously use Wikipedia as your
source of information?), then how do you expect to handle corrosive chemicals like oxalyl chloride or toxic stuff like 2,4,6-trichlorophenol? It is
obvious you have no experience whatsoever with practical chemistry and have no knowledge about theory, so I'm worried your first experiment might be
the last. Please start with simple and safe experiments first!
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Nicodem
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Thread Moved
7-5-2010 at 04:28 |
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