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Saber
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Acetonitrile form Ammonium acetate
Ammonium acetate is a very cheap chemical to buy and it is also easy to make- neutralise home vinegar with household ammonia ( although this will only
give a ~8% soloution) or simply neutralise glacial acetic acid with conc ammonia.
Ammonium acetate can be dehydrated to produce acetamide. I am not sure but this dehydration takes place at around 170 degrees C. Acetamide is a
possible human carcinogen so i dont tend to use the stuff alot.
Acetonitrile is widely used as a solvent, it is polar with a dipole moment of 3.84 D. It can be reacted with Cyanogen chloride to produce
malononitrile.
I have read somewhere that Acetamide can dehydrated to acetonitrile. Does anyone have any links or information on this?
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sonogashira
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Have a look in the library here. I know that Cohen has a preparation (using P2O5) as does Gatterman 
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Klute
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I think you woul dbetter be off making acetamide from ethyl acetate and conc. NH3 for a few days, gives a much cleaner product.
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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ScienceSquirrel
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One of the nicest preparations of acetamide is heating acetic acid with urea. The byproducts are ammonia and carbon dioxide and the acetamide is
distilled using an air condenser.
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Tsjerk
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urea with acetic acid
I performed this reaction and if you do it in a roundbottom flask with a water cooled condensor on top of a reasonable size (ns29 or bigger), you
don't need destillation.
The acetamide will solidify in the condensor nice and clean as fluffy cristals. Afterwords the acetamide is easily scraped out.
Works like a charm.
[Edited on by Tsjerk]
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Saber
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Hmm, thanks for the great replies!
@Klute - could you give me more information on this? Is it heating ammonia dissolved in water and ethyl acid under reflux? I dont see how the ammonia
in water would work as ethyl acetate only dissolves 3% water...
@ScienceSquirrel- Could this method be used for preparing other amides? eg. Formic acid + Urea--> Formamide followed by distilling formamide out?or
does it not work this way..?
Any ideas of converting Acetamide to Acetonitrile?
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tapira1
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Conversion of acetamide into MeCN
To perform the conversion you will need a dehydrating agent; however, in my experience, if you can get things like P2O5 there is no reason why not to
get MeCN; besides, the cost of your preparation will make the solvent hugely expensive
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Saber
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What about using a cheaper dehydrating material, eg Oleum?
I have my own mini contact process machine and i can generate oleum for about 50p a liter...
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DJF90
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Post pictures of your contact process plant!!! At 50p a liter thats amazing... what sort of size is it? Is it DIY? What material is it made from? I
know this is OT but this is incredible!
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Saber
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I built it out of glass. It uses a Vanadium pentoxide, K2SO4 catalyst mounted on silica.
I unfortunatly dont have a camera at the moment i will post some on a new thread
when i get some
It burns sulphur i get at £3 for 5kg so it is very cheap to use. My air source
is a air compresser, the air comming out being dried by 3 gas drying bottles of, yep you guessed it, conc sulphuric
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panziandi
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To make the acetonitrile you need to dehydrate the acetamide with either phosphorus pentoxide, phosphoryl chloride or thionyl chloride, I personally
think you should shop around for acetonitrile its not the cheapest solvent but it's not the most expensive... and this process is hugely expensive to
make a solvent such as that!
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Klute
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Acetamide is made by stirring Ethyl acetate and conc. NH3 at RT for a few dasy, until a homogeneous mixture forms: two layers turn to one. Then remove
the water, NH3, EtOh and AcOEt in excess, and you have white (rat smelling) acetamide. A recrystallization from EtOH can only help. I haev doen the
recationa few times and it works well. I have neevr tried the ammonium acetate or urea methods though, so hard to compare.
I think there has already been some discussion on the subject
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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MagicJigPipe
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I have NEVER heard of this method to acetonitrile. This is excellent! I'm going to try this as soon as I get some time. I don't yet have access to
phosphorus pentoxide (or P for that matter) but I do have plenty of EtOAc.
I can also obtain acetonitrile but it is very expensive. Expensive enough to actually make this worth it. (Possibly after a few runs to get the
efficiency up)
ScienceSquirrel, do you have more information on your method? Do you have a write-up? Is GAA needed?
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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smuv
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Acetonitrile can also be made from acetamide via vapor phase dehydration over basic aluminum phosphate.
I have attached a procedure to make propionitrile from propionamide (also included is a vapor phase dehydrogenation of alcohols) i expect this
procedure to be applicable to acetonitrile.
Attachment: vapor_phase_catalysed_reactions_propionitrile&alcohol_dehydrogenation.pdf (1021kB)
This file has been downloaded 1723 times
"Titanium tetrachloride…You sly temptress." --Walter Bishop
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S.C. Wack
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The corresponding procedure using acetic acid instead of propionic acid was done long before, using alumina on pumice.
http://www.sciencemadness.org/talk/viewthread.php?tid=4815&a...
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kclo4
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This is just for fun, or do you actually need it? I totally understand making it just for fun but if you want to do bigger and better projects with it
Why make it?
I see it for sale at one liter ACS for $28.30.
I don't know where you are from, of if this is a watched chemical for some reason, but I thought I would just mention it looks easy to buy.
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Saber
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I want to do this just for fun. I can buy Acetamide and acetonitrile quite cheap however i love making things.I can also get ethyl acetate for like
£2/1L so this method if it works will be usefull!
@smuv - have you ever tried this? It seems too good to be true! I do have around 500g of P2O5 i dont use however a simple basic ammonium phosphate
should last much longer! thanks for the prep!
Hmm i think i will try the Ethyl acetate and ammonia trick first then fractional distill the product to seperate remainding acetate and retrieve the
nitrile.
I am definitly gonna try the vapor phase dehydrogenation though, sounds intersting..
Thank guys!!
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Taoiseach
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urea with acetic acid
Is acetic anhydride necessary for this reaction to work?
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Formatik
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| Quote: | Originally posted by Taoiseach
urea with acetic acid
Is acetic anhydride necessary for this reaction to work? |
No, I don't think so. Gmelin says heating urea with AcOH to 110 deg.C. forms acetamide, pitty nothing further like reaction time, extraction, etc. but
they reference: M.T. Dangyan (Bull. Armenian Branch Acad. USSR 1942 No. 9/10 (23/4), pg. 53/72), C.A. 1946 3399, and
J.M. Das-Gupta (J. Indian Chem. Soc. 10 [1933] 117/23). These references, especially the first should have more details about this
process.
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ScienceSquirrel
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I think you will find the preparation in a book of practical organic chemistry, maybe Vogel.
Anyway this is pretty much how I remember it including the reference to mice 
http://nepenthes.lycaeum.org/Misc/methylamine.html#PART6
Acetic anhydride will probably yield a different product.
You need a good grade of glacial acetic acid. Acetic acid is very pure these days due to the way it is made ( carbonylation of methanol ) so almost
any reagent grade will do.
Note that quite a bit of ammonia is evolved.
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ScienceSquirrel
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Dehydration of amides to nitriles
Ammonium sulphamate is widely available in high purity, easy to handle and cheap as chips.
It has been used for the dehydration of amides to nitriles. The yield is a bit disappointing with acetamide, probably due to the low boiling point of
the amide but it is pretty good with the other amides.
http://article.pubs.nrc-cnrc.gc.ca/ppv/RPViewDoc?issn=1480-3...
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panziandi
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That is a good paper! Looks promising for higher and harder to get nitriles for use in further synthesis etc rather than as a preparative method for
acetonitrile. Even if you can't get ammonium sulphamate, I'm sure sulphamic acid is just as cheap and easier to come by and can be converted to the
ammonium salt. This does look like it will be worth a try at some point. I wonder what the possibilites are for dinitriles from diamides... It all
looks promising for larger batches when one would like to steer clear of the expensive, toxic and hard to get dehydrating agents usually used for
these reactions.
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mechem
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Can polyphosphoric acid be used to dehydrate acetamide.
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Vogelzang
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How about this?
http://books.google.com/books?id=Dv04AAAAMAAJ&pg=PA21&am...
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panziandi
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I would make sure the polyphosphoric acid is anhydrous by heating it under a vacuum for some time and then attempting it. But I wouldn't know what
yields to expect, that's if it would work. Perhaps give it a shot if you have some at hand? Be interesting to know!
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