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Author: Subject: Diethylamine Synthesis
mbrown3391
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[*] posted on 26-8-2008 at 07:27
Diethylamine Synthesis


After a bit of research i have found 3 mentioned ways to synthesize diethylamine:

1. N,N-Diethyl-3-methylbenzamide + Ethylene Glycol + NaOH + Heat

2. Ethylchloride + Ammonia (forms diethylamine HCL)

3. Ethanol + Ammonia + Sulfuric Acid

Are reactions #2 and #3 spontaneous? If not, what is needed to cause the reaction to proceed?

Also, do these methods produce diethylamine alone, or do they produce ethylamine and triethylamine as well?

Which seems to be the best choice?
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[*] posted on 26-8-2008 at 07:44


Making diethylamine is an awful fag.

Method 1 will produce small amounts of pure diethylamine at fairly high cost unless you can buy cheap DEET.

Methods 2 and 3 will produce mixtures that you will have to fractionate. Fine in industry, a right pig on a small scale in the lab.
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mbrown3391
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[*] posted on 26-8-2008 at 07:46


So do you know of any other, possibly more efficient methods?
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ScienceSquirrel
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[*] posted on 26-8-2008 at 08:02


I believe that you can react the dianion of cyanamide with an alkyl bromide to prepare a dialkyl cyanamide.
Hydrolysis and purification would yield the diethylamine.
Simple amines are worth buying if you can as they are cheap and not that easy to make on a small scale with laboratory type chemistry.
I would guess that industrially it is made by passing ethylene and ammonia over a catalyst. The reaction products are fractionated and recirculated as required and all three amines are produced at the same time.
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Arrhenius
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[*] posted on 26-8-2008 at 08:12


Method #2 is spontaneous, definitely, but will yield varying amounts of ethylamine, diethylamine, triethylamine and tetraethylammonium cation. The extend of each product is dependent on the quantity of reactants, and probably temperature. One would need an excess of ammonia to avoid tri/tetra-alkylation. Keep in mind this won't work with aqueous ammonia, only pure liquid ammonia or perhaps dissolved in an unreactive solvent.

Method #3 is not spontaneous. I'm guessing this involves the dehydration of ethanol to ethylene in order to react with ammonia, which requires heat. I'll try searching some literature, but this one's not panning out well in my head, I agree it's probably gas phase. It is likely that this reaction would produce more ethylamine than your desired diethylamine.

If you go via acylation, you may be able to acylate a primary amine, if you can produce the primary amine of your desired product.

[Edited on 26-8-2008 by Arrhenius]

[Edited on 26-8-2008 by Arrhenius]
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mbrown3391
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[*] posted on 26-8-2008 at 08:29


any idea what type of acylating agent / catylist would be used in this case?
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[*] posted on 26-8-2008 at 08:43


Acylation and reduction would work but it is a big no no on the grounds of cost.

You would have to react acetic acid with urea to from acetamide, reduce that to ethylamine and then react it with acetyl chloride to produce the N ethyacetamide. A final reduction would produce the desired diethylamine.
Hydrolysing DEET would be miles cheaper and easier.
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[*] posted on 26-8-2008 at 08:57


Buy N,N,-diethylformamide and hydrolyze it to diethylamine and formic acid, using HCl.

This method works for DMF -> dimethylamine so why not?

[Edited on 27-8-2008 by Sauron]




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[*] posted on 26-8-2008 at 08:58


acetyl chloride with the primary amine would be your best bet. Acetic anhydride or ketene would likely also work. This would require reduction with LAH, optimally. H2 + catalyst would probably work if done carefully, or NaBH4 + I2 or H2SO4 (not positive on this one).
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[*] posted on 26-8-2008 at 09:02


I've never heard of hydrolizing DMF... if you can cite this it would be appreciated.
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[*] posted on 26-8-2008 at 09:02


N,N-DiETHYLformamide hydrolyzes to diethylamine and formic acid, its constituents. Do this with concentrated hydrochloric acid or with dry HCl gas. The procedure ought to be in the literature.

Doing same with DMF gets you diMETHYLamine.

Diethylformamide is $55/100 g from Acros. So a lot more expensive than DMF. But not so bad. This gets youpure diethylamine hydrochloride uncontaminated by ethylamine or TEA.

Maybe there's a cheaper source with larger packing than Acros, too.

[Edited on 27-8-2008 by Sauron]




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[*] posted on 26-8-2008 at 09:04


No.. producing an alkyl-diethylamine. Read carefully.
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[*] posted on 26-8-2008 at 09:04


Quote:
Originally posted by Sauron
Buy N,N,-diethylforamide and hydrolyze it to diethylamine and formic acid, using HCl.

This method works for DMF -> dimethylamine so why not?


I think he wants a method that uses OTC materials.

He is not going to get diethylformamide down his local hardware store, phamacist or camping store.

He will probably get 100% DEET for £30 a litre if he shops around. Expensive, but cheaper on a mole for mole basis than diethylformamide.
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[*] posted on 26-8-2008 at 09:11


If you can do hydrogenation, it is possible to hydrogenate acetonitrile to get a mixture of products, though predominately mono & di alkyl.

I'm guessing you can't buy anything from Acros, Fisher, VWR, or any other commercial supplier (nor can I).... but feel free to peruse their prices.

[Edited on 26-8-2008 by Arrhenius]
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[*] posted on 26-8-2008 at 09:18


Well, that sort of lets out ketene and LAH or catalytic hydrogenation too doesn't it?

I'm fed up to here with all this bricks-without-straw OTC crap.

I routinely buy from Merck, Acros, Aldrich, Fluka, Panreac, Carlo Erba, Ajax Finechem, and others. But then I live in a free country and I have a registered corporation as well.

[Edited on 27-8-2008 by Sauron]




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[*] posted on 26-8-2008 at 09:23


I wouldn't say catalytic hydrogenation is out of reach of the hobbyist, nor ketene. LAH is nearly out of reach, but sodium borohydride is not quite. On the other hand, Acros is out of reach, unless you're playing middleman.

MrBrown wishes to make diethylamine, so I'll offer my small amount of knowledge to him. I can think of a few reactions that certainly don't need very much of it... so maybe 10% yield is okay.

Power to you... we would all love to own a commercial lab, and live in a "free" country, but you have to make money with it to pay the bills in the West.

[Edited on 26-8-2008 by Arrhenius]
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[*] posted on 26-8-2008 at 09:24


Quote:
Originally posted by Sauron
Well, that sort of lets out ketene and LAH or catalytic hydrogenation too doesn't it?

I'm fed up to here with all this bricks-without-straw OTC crap.


The next thing he will be looking to make lysergic acid from icing sugar, brick dust and seagull poop fermented in the cellar for one month in a dried out catskin and then extracted with Everclear :D

Anyway there is no point in making it if you can deal with Sigma et al as the stuff is cheap as chips.

[Edited on 26-8-2008 by ScienceSquirrel]
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[*] posted on 26-8-2008 at 09:29


Yeah that's what questions about OTC diethamine from the clueless, dazed and confused set are usually all about, sad to say.

Not that I am pointing a finger at this particular newbie, I'm sure he's an eagle scout trying for his merit badge in chemistry.




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[*] posted on 26-8-2008 at 09:35


Hmm.. so this is a forum for professional chemists? Your postings are really helpful, thank you so very much.
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[*] posted on 26-8-2008 at 09:49


If you have a look back through my postings I do make some helpful suggestions.

The best way to make diethylamine at home is the hydrolysis of DEET (Method 1 in the original post)
It can be carried out with a modicum of glassware in a simple lab setup.

However it is not cheap.

I occasionally mock some posters as they come on here looking to make something that is a known precursor of a drug and they do not say why they want it or cannot go through the usual suppliers.
Also it is often the only thing that they are interested in or they display very little chemical knowledge.
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[*] posted on 26-8-2008 at 09:50


Make money with my company? What a novel idea. The company is a black hole and my money disappears over the event horizon. The country is Thailand. The local agents for all those suppliers and more are happy to sell to a registered company. If what I want is not in local stock I must wait 30-60-90 days for delivery.

I keep my nose clean so the government is not a nuisance.

Some things are verboten. CHCl3, CCl4, ethylene chloride, ethylene bromide. SO2, Cl2, SOCl2, SO2Cl2, PCl3, POCl3, PCl5. But I2 is no problem. AcdCl is restricted so is Ac2O. But in general all these can be made if and when I need them.

Ketene? If you have a hood and a SCBA or supplied air maybe. Hydrogenation? Some people on this forum have medium pressure autoclaves rated 1900 psi. But not many. My point is, your advise to a guy who must go OTC to acquire a secondary aliphatic amine, seems a little esoteric, not to mention expensive. And in the case of ketene probably lethal.




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[*] posted on 26-8-2008 at 09:57


Quote:
Originally posted by ScienceSquirrel

Method 1 will produce small amounts of pure diethylamine at fairly high cost unless you can buy cheap DEET.


Commercial DEET (25% concentration) is available OTC in most 'big box' stores in the U.S.: http://www.deet.com/ It is said to be stable in the pH range of 5-9, so hydrolysis under highly acidic or highly basic conditions looks feasible but I could not locate a recipe in the first several pages of Google results I browsed through.




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[*] posted on 26-8-2008 at 10:55


The camping stores are thinking about sales around here and we can buy 100% DEET in Western Europe.
If I can spot some going cheap I might have a go at hydrolysing it.

[Edited on 26-8-2008 by ScienceSquirrel]
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[*] posted on 26-8-2008 at 11:12


Quote:
Originally posted by ScienceSquirrel
The camping stores are thinking about sales around here and we can buy 100% DEET in Western Europe.
If I can spot some going cheap I might have a go at hydrolysing it.

[Edited on 26-8-2008 by ScienceSquirrel]


If you used aq HCl you would wind up with a preciptate of 3-methylbenzoic acid & the amine hydrochloride in solution. If you used aq NaOH you would wind up with the amine base (volatile, bp 55-56 deg C) & the Na salt of the acid in solution. I think that procedures are probably out there or could be developed by the amateur chemist for either approach.

http://chemicalland21.com/industrialchem/organic/DIETHYLAMIN...



[Edited on 26-8-2008 by Ritter]




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mbrown3391
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[*] posted on 26-8-2008 at 13:06


Ok a few more questions.

First, does diethylamine form an azeotrope with either ethylamine or triethylamine?
Second, would reaction #2 work either with all gaseous reactants, or maybe with gaseous ammonia bubbled through liquid Ethyl chloride?

[Edited on 26-8-2008 by mbrown3391]
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