Author Topic: Ethylamine Synthesis?  (Read 302 times)

roofies44

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Ethylamine Synthesis?
« on: August 28, 2010, 05:56:23 PM »
What is the most practical way for synthesizing ethylamine for a home chemist?
Commercially it is made from ammonia and ethanol, but I'd imagine working with ammonia would be a pain in the ass.

Wikipedia writes:
Hydrogenation of acetonitrile, acetamide, and nitroethane affords ethylamine. These reactions can be effected stoichiometrically using lithium aluminium hydride. In another route, ethylamine can be synthesized via nucleophilic substitution of a haloethane (such as chloroethane or bromoethane) with ammonia, utilizing a strong base such as potassium hydroxide. This method affords significant amounts of byproducts, including diethylamine and triethylamine.[4]

The methylamine FAQ writes:
" This route is also applicable to other nitroalkanes (eg - ethylamine from nitroethane) "
http://designer-drugs.com/pte/12.162.180.114/dcd/chemistry/eleusis/methylamine27.html
This seems like a fine procedure, unfortunately the cost of nitroethane is kinda high.

How about procedures for making ethylamine from acetonitrile and acetamide? These chemicals are much cheaper then nitroethane, and easier to acquire. I am not sure how difficult haloethanes are to acquire.

Vesp

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Re: Ethylamine Synthesis?
« Reply #1 on: August 28, 2010, 06:35:51 PM »
There is some discussion on this else where on the site I believe. Producing EtBr via HBr and EtOH, than reacting the EtBr with ammonia ought to produce EtNH2*HBr - however, I do not know the yield in which it does, or what other impurities might be present. I'g search a bit on this site if you haven't already - not to sure what you'll find... 

Other things to consider would be using acetaldehyde and trying to make it like methylamine is made from formaldehyde. Even produce a hexamine variant, if at all possible? Acetaldehyde however, is not the most common place chemical and making it in a decent amount might become a pretty decent project on its own.

Also if acetamide via the hoffman degradation produces methylamine - propamide ought to find use here - though, again not the easiest chemical to obtain AFAIK.

http://127.0.0.1/talk/index.php/topic,275.0.html
http://127.0.0.1/talk/index.php/topic,32.0.html

Might be useful, might be other useful ones as well...




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lugh

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Re: Ethylamine Synthesis?
« Reply #2 on: August 28, 2010, 07:17:45 PM »
Acetaldehyde can be produced via oxidation of ethanol  ;) You can reduce acetaldehyde oxime with activated aluminum to get ethylamine  8)
« Last Edit: August 28, 2010, 07:20:32 PM by lugh »
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no1uno

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Re: Ethylamine Synthesis?
« Reply #3 on: August 29, 2010, 12:40:25 AM »
Chloroethane + ammonia is the industrial preparation. There are several papers on the preparation of EtCl (using zinc chloride and HCl) about the place. Actually, if anyone has the bulk of the papers on the preparation of EtCl and EtNH2 therefrom (I've put them up several places) please throw them up - methinks they may be counted amongst the papers I lost...
« Last Edit: August 29, 2010, 12:48:57 AM by no1uno »
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lugh

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Re: Ethylamine Synthesis?
« Reply #4 on: August 29, 2010, 03:00:59 AM »
Industrial methods are largely based on the economies of scale and shareholder's profits  ;D  Pilot plant scale is rather similar in the case of industrial practice  :P  Clandestine chemistry ranges from industrial scale all the way down to micro chemistry bench work, depending on the circumstances   :D   Most clandestine chemistry is done in kitchens, laundry rooms and bath rooms, and thus is bench scale   :-X  Bench scale chemistry is generally done in a manner to save the time of the worker, and that becomes even more of a consideration in clandestine chemistry  :o  The best method in terms of convenience for preparing ethyl chloride in the laboratory was published in JACS 61, 1415 (1939)  ;)  Ethanol is reacted with aluminum chloride at 150 º C to produce ethyl chloride in a 97.6 % yield  8)
« Last Edit: August 30, 2010, 12:08:56 AM by lugh »
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Vesp

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Re: Ethylamine Synthesis?
« Reply #5 on: August 29, 2010, 03:20:44 AM »
Personally I'd go with using EtBr if that is an option since that is a pretty easy synthesis, while using AlCl3 complicates things to some degree. AlCl3 is obviously going to be a bit tricky to get, however  I have reacted HCl with Al in an alcohol - so making it insinuation would than produce EtCl - I am guessing you need very dry EtOH and HCl(g) for the reaction to proceed with great yields though.
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lugh

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Re: Ethylamine Synthesis?
« Reply #6 on: August 29, 2010, 03:53:37 AM »
The acetaldehyde oxime route is probably the simplest procedure for the amateur chemist:

Place 260 mL of 23% sulfuric acid in a 1500-mL Florence flask. Connect an addition funnel to the flask, and set it up for vacuum distillation with a 500-mL receiving flask. The receiving flask should be immersed in a salt-ice bath to cool the distillate when it comes over. Although a setup for vacuum distillation is used, it is not necessary to apply a vacuum; the vacuum adapter merely provides a means of equalizing pressure. Prepare a solution of 100 g of sodium dichromate in 200 mL of water and 127 mL of ethyl alcohol. Factor in the amount of water that is already in the ethyl alcohol when making the solution, i.e. 100 mL of 95% alcohol has 5 mL of water in it already. Place this solution in the addition funnel, position the stem of the funnel so that it is about 3 cm above the surface of the acid. Heat the acid until it just begins to boil, then add the mixture in the funnel in a steady stream to the acid. It will not be necessary to heat the flask during the addition because it will generate its own heat. The heat will be sufficient to distill over the acetaldehyde along some alcohol and waste acetal. If acetaldehyde vapors begin to escape from the flask, regulate the distillation by decreasing the amount of dichromate solution being added. If the reaction flask does not boil on its own, gently heat it for a short time until boiling begins. The crude acetaldehyde thus obtained is difficult to distill from the alcohol and acetal mixed with it. It is therefore converted to aldehyde-ammonia, then back to pure aldehyde. Place the crude acetaldehyde in a Florence flask of suitable volume to contain no more than two thirds of the liquid. Attach a reflux condenser to the flask. Fill the condenser jacket with 30 °C water. It is only necessary to have the warm water in the jacket, not flowing. Stop up the lower connecter to prevent water from leaking out. To the top of the condenser, attach a glass tube connected to a wash bottle filled with 50 mL of ether. This wash bottle is then connected to another wash bottle filled with 50 mL of ether. After all connections have been made, the crude aldehyde is heated to a gentle boil for 5-10 minutes. The ether will absorb the acetaldehyde as it boils off. If the ether begins to rise up into the connecting tube from the condenser to the wash bottle, increase the heating. Combine the ether into a 150-mL beaker immersed in a salt-ice bath. Bubble dry ammonia gas into the ether through a funnel or wide tube immersed near the bottom of the beaker. Add ammonia until the ethereal solution smells strongly of ammonia. After about an hour, pure ammonia-aldehyde should have separated out. Scrape the crystals from the beaker and collect them by suction filtration. Wash crystals with a small amount of ether, and allow them to dry in a desiccator. The yield is about 30 g. To obtain pure acetaldehyde, dissolve 10 g of aldehyde-ammonia in 10 mL of water in a 50-mL Florence flask. Add 28 mL of cold 29% sulfuric acid to the flask and set it up for simple distillation. Heat the flask on a water bath to distill over the aldehyde. Place the receiving flask in a salt-ice bath to cool the volatile acetaldehyde. Acetaldehyde is extremely volatile and cannot be stored satisfactorily unless it is refrigerated or sealed in glass ampoules (not just capped), therefore it is necessary to prepare acetaldehyde each time it is needed. There is, however, an easier solution. A quick and easy way to store acetaldehyde is to polymerize it to paraldehyde, which can be handled and stored easily, then depolymerize when you need to use it. Now you can make a larger amount without worry. To polymerize acetaldehyde for storage, place it in a dry test tube and cautiously add 1 drop of concentrated sulfuric acid per 2 mL of acetaldehyde in the tube. Mix thoroughly, the polymerization will begin to take place. Some gentle warming can hasten the reaction. After some minutes add 3-4 mL of water per 2 mL of acetaldehyde, an insoluble precipitate of paraldehyde will form. As an aside, technically paraldehyde is a controlled substance. It is a sedative and a hypnotic drug useable by prescription only. To depolymerize paraldehyde back into acetaldehyde, place the paraldehyde into a round-bottom 200-mL Florence flask. Add 4-5 drops of concentrated sulfuric acid for every 20 g (20 mL) of paraldehyde in the flask. Set the flask up for fractional distillation, use glass in the fractionating column. Use a 125-mL Erlenmeyer flask as the receiver; keep it cool by immersing in an ice water (but not salt-ice) bath. Place a loose plug of cotton into the Erlenmeyer flask to help reduce evaporation loss; it must be loose. Care must be taken to prevent the cotton from coming into contact with the distillate. After setting up, heat the flask gently. The temperature of the distillate must not be allowed to rise above 35 °C as it will only repolymerize. The acetaldehyde is now ready for use.


 8)
« Last Edit: August 29, 2010, 04:23:51 AM by lugh »
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lugh

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Re: Ethylamine Synthesis?
« Reply #7 on: August 29, 2010, 06:59:24 AM »
The acetaldehye-ammonia complex can be reduced to ethylamine using zinc dust and hydrochloric acid or electrolytically in acid solution  8)
« Last Edit: August 29, 2010, 02:52:06 PM by lugh »
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no1uno

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Re: Ethylamine Synthesis?
« Reply #8 on: August 29, 2010, 08:07:42 AM »
Found some of the Ethyl Chloride references I've previously had (but lost), I'll throw them up here. I'm busily trying to find the remainder of the papers I used to have. For the sealed tube, pretty much any heavy walled, HDPE/HDPP container should do.
« Last Edit: August 29, 2010, 10:20:55 PM by no1uno »
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Sedit

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Re: Ethylamine Synthesis?
« Reply #9 on: August 31, 2010, 01:17:05 AM »
I am with Vesp if the EtX is the desired route. As far as making Haloethanes is concerned EtBr is the way to go and I have a synthesis posted on here using simple over the counter products so using the search engine will provide you with all you need to get there.

Make sure you have a 10x molar excess of NH3 to EtBr else you will get di and tri ethylamines as the main products. Where as in industry this is a problem on a small scale home setting this should not be an issue as long as the EtBr is slowly added to NH3 solution.

Never forget the Delphin reaction on this one because its not like bromosafrole and there is no steric hinderence in this case and its exactly what this and other simular reactions where made for.
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no1uno

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Re: Ethylamine Synthesis?
« Reply #10 on: August 31, 2010, 01:54:54 AM »
That is the benefit of the posted synthesis via EtCl - the monoethylamine hydrochloride and quaternary tetraethylammonium chloride are the main products. Separation of those two is going to be way simpler than the separation of the mono-, di- and triethylamines.
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Sedit

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Re: Ethylamine Synthesis?
« Reply #11 on: August 31, 2010, 01:58:39 AM »
Seriously?

Well lets put BP into perspective

Tri       89.7 °C,
Di        55.5 °C
Mono   16.6 °C

Seperation would be much easier then wiping my own ass.
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Vesp

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Re: Ethylamine Synthesis?
« Reply #12 on: August 31, 2010, 02:19:41 AM »
That view *might* be a bit simplistic - I find it pretty likely that an azeotrope could form...

I wonder if their pH is of any importance? perhaps they could be separated that way as well, though I doubt it.
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Sedit

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Re: Ethylamine Synthesis?
« Reply #13 on: August 31, 2010, 02:48:23 AM »
I find it highly unlikely to encounter and azeotrope given the wide range in BP and the relatively large variationin structure I feel that seperation could very well be that easy.
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no1uno

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Re: Ethylamine Synthesis?
« Reply #14 on: August 31, 2010, 07:22:53 AM »
And the partial pressure above the mixture?

Apart from that, why the fucking agro? I can't think of what I've done to earn it, but I'm easy, I haven't even returned it. Call me on it and we'll see. :-X
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Sedit

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Re: Ethylamine Synthesis?
« Reply #15 on: September 01, 2010, 12:19:15 AM »
Don't stress it No1uno I mean no attitude I just dont have much time to type anymore so I must make each post short and sweet which according to a few different people they seem to take it as ignorent where as its just the bear essentials being typed. No ill will intended.
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roofies44

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Re: Ethylamine Synthesis?
« Reply #16 on: September 01, 2010, 10:18:29 PM »
not everyone has time for tweaker length posts no1uno   ;)

roofies44

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Re: Ethylamine Synthesis?
« Reply #17 on: September 10, 2010, 09:56:02 AM »
must the ammonia be anhydrous for this method, or can a 25% aqueous solution be used?
sedit mentions that it is a solution, but is there any minimum concentration threshold?
« Last Edit: September 10, 2010, 09:59:33 AM by roofies44 »

Sedit

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Re: Ethylamine Synthesis?
« Reply #18 on: September 11, 2010, 02:26:03 AM »
The answers to your questions can be found with relative ease with abit of research. Please simply google Ethylamine synthesis and tell us if it needs to be anhydrous or if a solution would work. The more effort shown by the person asking a question the more help they receive all though out the internet. Any confusion after a quick search and I as well as everyone that knows would be more then happy to help.

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roofies44

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Re: Ethylamine Synthesis?
« Reply #19 on: September 11, 2010, 07:05:54 PM »


The halogenoalkane is heated with a concentrated solution of ammonia in ethanol. The reaction is carried out in a sealed tube. You couldn't heat this mixture under reflux, because the ammonia would simply escape up the condenser as a gas.

So could this be done in a steel "pipe bomb"?
« Last Edit: September 11, 2010, 07:11:13 PM by roofies44 »