runlabrun
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acetonitrile synthesis
Hi all,
Im looking for a simple method to produce acetonitrile, one i have in mind after thinking about it for a moment is the dehydration of acetamide with
phosphorus pentoxide?
3CH3CONH2 + P2O5 --> 2H3PO4 + 3CH3CN
I have some red phosphorus which i can burn to produce the phosphorus pentoxide and the acetamide i presume could be made by the thermal decomposition
of ammonium acetate at temperatures > 120oC... is this possible?
This method although is a bit tedious and requires the expenditure of red phosphorus (difficult comodity to find these days due to some people in
society).... but it all i could think of on the spot... anyone else have some ideas or is this the only way you can think of too???
Thanks
-rlr
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S.C. Wack
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Try looking with the search engine. A patent has come up before.
Since they aren't doing much sitting on my computer, here are two papers by Epps and Reid that appeared in JACS 38 (1916), pp. 2120-2135. The
first is on dry distillation of (un)saturated aliphatic and aromatic acid salts with metal thiocyanates under various conditions. The second is uses
thoria or alumina, acetic acid, and excess NH3, heated to various temperatures in a copper tube. Whether of not you like them for your situation - or
are less useful than the patent - they are good papers detailing many varied experiments, so here they are.
Attachment: nitriles.zip (926kB)
This file has been downloaded 1579 times
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BASF
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Acetonitrile from NH4-acetate
Acetonitrile prep
PATENT SPECIFICATION
Application Date: Oct 10, 1935 No 28007/35.
464,106 Complete Specification Left: Sept 23, 1936.
Complete Specification Accepted: April 12,1937.
PROVISIONAL SPECIFICATION
Improvements in or relating to the Manufacture of Aliphatic Acid Nitriles We, BRITISH CFLANES:S LIMITED, a Company incorporated in accordance with the
laws of Great Britain, of Celanese House, 22 & 23, Hanover Square, London, S W 1, HORACE FINNINGLEY OXLEY and EDWARD BOADEN THOMAS, both subjects
of the King of Great Britain, of the Works of British Celanese Limited, Spondon, near Derby, do hereby declare the nature of this invention to be as
follows:This invention relates to the manufacture of aliphatie acid nitriles and especially acetonitrile and the nitriles of other lower fatty acids.
According to the invention an aliphatic acid nitrile is produced by decomposing by the action of heat the ammonium salt of the corresponding aliphatic
acid in presence in the free state of a quantity of the same acid The production of acetonitrile, which is an important embodiment of the invention,
is thus effected by decomposing amllonium acetate by the action of heat in presence of a quantity of free acetic acid.
In carrying out the process of the invention the ammonium salt to be decomposed may be heated under a fractionating column, together with a quantity
of the corresponding acid in the free state, under conditions such that the nitrile will distil off as it is produced.
In such a process the presence of a quantity of free acid equal to about 40% of that combined in the ammonium salt gives excellent results and avoids
the presence of substantial quantities of unchanged ammonium salt in the distillate.
Larger quantities of acid may be employed, if desired, although it is found that no advantage is secured by using a quantity of free acid greater than
that combined in the salt.
4,5 In practice it has been found that the quantity of free acid thus employed may be reduced very substantially by carrying out the production of the
nitrile as a continuous operation This object may be achieved by heating the mixture of ammonium salt and free acid to the decomposition temperature
under a fractionating column, operated so as to permit distillation into a suitable receiver of the nitrile as it is formed, and provid 55 ing a
continuous supply of fresh ammonium salt-acid mixture to the distillation vessel Operating in this manner it has been found possible to obtain
excellent results by supplying to 60 the distillation vessel a mixture containing free acid equal to 15-20 % of that combined in the ammonium salt
Such a mixture may be maintained in a liquid form suitable for continuous feeding by 65 warming e g to a temperature of 60-7 00 C.
In such a process the distillation vessel may, if desired, be charged initially with a mixture containing a rather larger 70 proportion of free acid
than is present in the mixture continuously supplied; for instance the vessel may be charged with a mixture containing free acid in quantity equal to
20-50 % of the weight of 75 the acid combined in the ammonium salt employed.
The decomposition temperature employod may be varied according to the particular nitrile to be produced, and 80 according to other operating
conditions.
In general, temperatures of 200-220 C.
are very suitable for the production of acetonitrile, temperatures of 200-210 C.
being very satisfactory Where, as will 85 usually be the case in practice, the distillation is effected under a fractionating column, the head of the
column should be maintained at a temperature such that the nitrile distills over while the free 90 acid is as far as' possible returned to the
distillation vessel In the production of acetonitrile a still-head temperature of about 92 C has been found very satisfactory in practice 95 It has
been found that the production of the nitriles can be accelerated very considerablv by the use of an iron catalyst.
The iron mav he introduced into the distillation vessel in the form of a compound 100 and phosphates of iron, e g Fe{( 12 POG) have been found very
suitable for use in this manner Alternatively, a distillation vessel made of a corrosive-resistant ferrous alloy such a Stavbrite may be 105 employed,
in which case it is found that % 00 %A, a ITT-246,O the small amount of corrosion which does take place is sufficient to provide the iron catalyst.
Separation of the nitrile produced from the distillate obtained may be effected in any desired manner, for instance by fractional distillation, if
desired, after the addition of sufficient acetic acid to convert all the acetate present into acid acetate and thus prevent distillation of ammonia.
The aqueous nitriles contaminated with the ammonium salt of the corresponding acid obtained in the process of the present invention may be purified
very efficiently by a process comprising salting out the nitrile with the ammonium salt This may be effected by neutralising with ammonia free acid
contained in the crude nitrile, and if necessary, adding a further quantity of the ammonium salt.
Such a salting out process produces in the case of acetonitrile an upper layer of aqueous nitrile of 95 % concentration, which, o-n fractionation,
yields first a constant boiling nitrile-water mixture containing 84 % nitrile and subsequently the anhydrous nitrile It is possible by this means to
obtain the bulk of the nitrile contained in the crude product in an anhydrous condition.
Fractionation of the ammonium acetate layer irom the salting out operation yields a distillate consisting of aqueous 35 nitrile containing free
ammonia which can be used in neutralising a further batch of crude nitrile, and so likewise can ammonia obtained from the 84 % nitrile obtained by
fractionating the 40 salted out product The residue from the fractionation of the ammonium acetate layer consists of ammonium acetate and the acid
acetate and is available for use as starting material in the pro 45 duction of a further quantity of nitrile.
While the invention has been described above more particularly with regard to the manufacture of acetonitrile it is not limited in this respect and
may be applied 50 to the manufacture of other aliphatic acid nitriles For example, by employing ammonium propionate as starting material propionitrile
may be produced and likewise from ammonium butyrate 55 there may be obtained butyronitrile.
Dated this 9th day of October, 1935.
STEPHENS & ALLEN, Chartered Patent Agents, Celanese House, 22 & 23, Hanover Square, London, W l.
COMPLETE SPECIFICATION
Improvements in or relating to the Manufacture of Aliphatic Acid Nitriles We, BRITISH CELANE Sn, L Im I Tn D, a Company incorporated in accordance
with the laws of Great Britain, of Celanese go House, 22 & 23, Hanover Square, London, W.1, HORACE FINNINGLEY OX:LY and E Dw ARD BOADEN T Hom As,
both subjects of the King of Great Britain, of the Works of British Celanese Limited, d B Spondon, near Derby, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement:-
This invention relates to the manufacture of aliphatic acid nitriles and especially acetonitrile and the nitriles of other lower fatty acids.
According to the invention an aliphatic acid nitrile is produced by decomposing by the action of heat the ammonium salt of the corresponding aliphatic
acid in presence in the free state of a quantity of the same acid The production of aceionitrile, which is an important embodiment of the invention,
is thus effected by decomposing ammonium acetate by the action of heat in presence of a quantity of free acetic acid.
In carrying out the, process of the 85 invention the ammonium salt to be decomposed may be heated under a fractionating column, together with a
quantity of the corresponding acid in the free state, under conditions such that the 90 nitrile will distil off as it is produced.
In such a process the presence of a quantity of free acid equal to about 40% of that combined in the ammonium salt gives excelent results and avoids
the 95 presence of substantial quantities of unchanged ammonium salt in the distillate.
Larger quantities of acid may be employed, if desired, although it is found that no advantage is secured by 100 using a quantity of free acid greater
than that combined in the salt.
In practice it has been found that the quantity of free acid thus employed may be reduced very substantially by carry 105 ing out the production of
the nitrile as a continuous operation This object may be achieved by heating the mixture of ammonium salt and free acid to the decompqsition
temperature under a frac 110 464,1 OU a 464,106 tion ating column, operated so as to permit distillation into a suitable receiver of the nitrile as it
is formed, and providing a continuous supply of fresh ammonium salt-acid mixture to the distillation vessel Operating in this manner it has been found
possible to obtain excellent results by supplying to the distillation vessel a mixture containing free acid equal to 15-90 % of that combined in the
ammonium salt Such a mixture may be maintained in a liquid form suitable for continuous feeding by warming e g to a temperature of 60-700 C.
In such a process the distillation vessel may, if desired, be charged initially with a mixture containing a rather larger proportion of free acid than
is present in the mixture continuously supplied; for instance the vessel may be charged with a mixture' containing free acid in quantity equal to
20-50 % of the weight of the acid combined in tbh ammonium salt employed.
The decomposition temperature employed may be varied according to the particular nitrile to be produced, and according to other operating conditions.
In general, temperatures of 200-2290 C.
are very suitable for the production of acetonitrile, temperatures of 200-210 C.
being very satisfactory Where, as will usually be the case in practice, the distillation is effected under a fractionating column, the head of the
column should be maintained at a temperature such that the nitrile distills over while the free acid is as far as possible returned to the
distillation vessel In the production of acetonitrile a still-head temperature of about, 920 C has been found very satisfactory in practice.
It has been found that the production of the nitriles can be accelerated very considerably by the use of an iron catalyst.
The iron may be introduced into the distillation vessel in the form of a compound and phosphates of iron, e g Fe(l 12 P 4), have been found very
suitable for use in this manner Alternatively, a, distillation vessel made of a corrosive-resistant ferrous alloy such a Staybrite may be employed, in
which case it is found that the small amount of corrosion which does take place is sufficient to provide, the iron catalyst.
Separation of the nitrile produced from the distillate obtained may be effected in ( any desired manner, for instance by fractional distillation, if
desired, after the addition of sufficient acetic acid to convert all the acetate present into acid acetate and thus prevent distillation of ammonia.
The aqueous nitriles conlandnated with the ammonium salt of the corresponding acid obtained in the process of the present invention may be purified
very efficiently by a process comprising Malt 70 ing out the nitrile with the ammonium salt This may be efiected by neutralising with ammonia free
acid contained in the crude nitrile, and if necessary adding a further quantity of the ammllo 75 nium salt.
Such a salting out process produces in the case of acetonitrile an upper layer of aqueous nitrile of 95 % concentration, which, on fractionation,
yields first a con 80 stant boiling nitrile-water mixture containing 84 % nitrile and subsequently the anhydrous nitrile It is possible by this means
to obtain the bulk of the nitrile contained in the crude product in an 85 anhydrous condition.
Fractionation of the ammonium acetate layer from the salting out operation yields a distillate consisting of aqueous nitrile containing free ammonia
which 90 can be used in neutralising a further batch of crude nitrile, and so likewise can ammonia obtained from the 84 % nitrile obtained by
fractionating the salted out product The residue from 95 the fractionation of the ammonium acetate layer consists of ammonium acetate and the acid
acetate and is available for use as starting material in the production of a further quantity of nitrile 100 While the invention has been described
above more particularly with regard to the manufacture of acetonitrile it is not limited in this respect and may be applied to the manufacture of
other aliphatic acid 105 nitriles For example, by employing ammonium propionate as starting material propionitrile may be produced and likewise from
ammonium butvrate there may be obtained butyronitrile 110 The following Example illustrates the invention as applied to the production of
acetonitrile:EXAMPLE.
A mixture of about 88 % amnionium 115 acetate and 12 % acetic acid, prepared by adding acetic acid to ammonium carbonate, is continuously fed to a
still provided with a Viigreux column and containing either a quantity of the feed mixture 120 or a residue from a previous operation.
[Edited on 18-11-2005 by BASF]
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Siddy
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Does this work:
MeOH + HCN > CH3CN + H20
Methanol + Hydrogen Cyanide > Acetonitrile + water?
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evil_lurker
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| Quote: | Originally posted by Siddy
Does this work:
MeOH + HCN > CH3CN + H20
Methanol + Hydrogen Cyanide > Acetonitrile + water? |
No it won't work. You might could get methyl chloride to react, but that would be rather difficult since its a gas.
Not all chemicals are bad. Without chemicals such as hydrogen and oxygen, for example, there would be no way to make water, a vital ingredient in
beer.
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Jor
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If you have a source, buy acetonitril. Its available commercially and it's not expensive. Fisher has 1 Liter very pure for 14,00.
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MagicJigPipe
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As far as I know, Fisher doesn't sell to individuals and I'm pretty sure they have ways of making sure you are a legitimate business.
Although, I just ordered some catalogs with a pretend business. I'm sure that's the only thing you can do.
"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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Siddy
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| Quote: | Originally posted by evil_lurker
| Quote: | Originally posted by Siddy
Does this work:
MeOH + HCN > CH3CN + H20
Methanol + Hydrogen Cyanide > Acetonitrile + water? |
No it won't work. You might could get methyl chloride to react, but that would be rather difficult since its a gas. |
Do you mean:
MeCl + HCN > CH3CN + HCl
or maybe
MeCl + NaCN > CH3CN + NaCl
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WizardX
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| Quote: | Originally posted by runlabrun
Hi all,
Im looking for a simple method to produce acetonitrile, one i have in mind after thinking about it for a moment is the dehydration of acetamide with
phosphorus pentoxide?
3CH3CONH2 + P2O5 --> 2H3PO4 + 3CH3CN
I have some red phosphorus which i can burn to produce the phosphorus pentoxide and the acetamide i presume could be made by the thermal decomposition
of ammonium acetate at temperatures > 120oC... is this possible?
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If you can't purchase acetonitrile, then use acetamide as the precursor and follow either of the procedures below.
MALONONITRILE http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0535
Substitute moles of cyanoacetamide with acetamide.
NICOTINONITRILE http://www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0706
Substitute moles of nicotinamide with acetamide.
Albert Einstein - \"Great ideas often receive violent opposition from mediocre minds.\"
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garage chemist
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Phosphorus Pentoxide is much cheaper than red Phosphorus, and not subject to regulation as it is not a drug precursor.
It should never be necessary to prepare phosphorus pentoxide oneself.
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Jor
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| Quote: | Originally posted by MagicJigPipe
As far as I know, Fisher doesn't sell to individuals and I'm pretty sure they have ways of making sure you are a legitimate business.
Although, I just ordered some catalogs with a pretend business. I'm sure that's the only thing you can do. |
I exactly thought the same one month ago. But the thing is, you have to find a supplier that sells to individuals and e-mail him if he can order from
Fisher for you. However expect a 20% price increase. I did this with a local supplier and now I have a lot of stuff from there.
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chemrox
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acetonitrile is cheap and readily available, even in the US. are you doing this for the fun of it?
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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S.C. Wack
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Well the top left of the screen does say amateur experimentalism, not amateur shopping.
Although acetonitrile was not the object of this article, the preparation of benzonitrile here uses the thiocyanate method, and also alternatives to
thiocyanate itself.
http://books.google.com/books?id=AcsAAAAAYAAJ&pg=PA162
Now that zips that used to work here no longer do, including mine above, I'm resetting my above pair of pdfs as a single one.
[Edited on 9-1-2009 by S.C. Wack]
Attachment: jacs_38_2120_1916.pdf (998kB)
This file has been downloaded 1096 times
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unionised
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There's an acetonitrile shortage at the moment so this thread might come in handy.
http://www.sepsci.com/chromforum/viewtopic.php?p=44184
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Artemisia
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Not just acetonitrile. Diethyl ether too. but no-one is really talking about it. Fisher have just started supplying ether again after an 8 week pause,
but its something silly like 40 quid a bottle now. Still, I can get my Grignards done so I'm happy! Just out of interest, why does the original poster
(runlabrun) want acetonitrile?
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DJF90
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Its a useful solvent in organic synthesis, just like ethanol, DCM, ether, DMSO etc.
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Artemisia
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hmm, stating the obvious a little. The only reason I asked was to see if acetonitrile could be substituted for another solvent for the application
required. I've just noticed the date of the original post though! still a newbie here...
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Vogelzang
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Look at
The Reactions of Calcium Carbide with the Vapors of Certain Organic Compounds
By A. J. McGrail
page 21
http://books.google.com/books?id=Dv04AAAAMAAJ&printsec=f...
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JohnWW
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CaC2 reacts with organic vapors? As the stuff contains the -C[triplebond]C- dianion, that sounds as if it might be a means of producing alkyne
compounds, by nucleophilic reaction with carbocations or with carbons bearing a significant positive charge.
BTW Is that book on Google a complete e-book, or just one of the thousands of grossly incomplete books on books.google.com (only incomplete in spite
of the copyrights of many of them having expired)?
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not_important
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It's a dissertation, and appears to complete. Not too many useful reactions, the most interesting is with acetaldehyde to give acetonitrile.
[Edited on 28-1-2009 by not_important]
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panziandi
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Of interest may be this document: http://www.rsc.org/ej/CC/2007/b614061k.pdf which is a ChemComm article detailing the preparation of nitriles from amides. The amide is coupled
with ethyl or phenyl dichlorophosphate, and eliminated with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Aurthors claim that many dehydrating agents are
available to transform amides to nitriles but the mild nature of this system is "unprecedented". Nothing on making acetonitrile from this method but a
wealth of examples of aromatic nitriles in very high yields >90%. Other bases are described such as Et3N and Pyridine were tried with lower
yields...
Thoughts?
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DJF90
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How about displacement of a halogen from Me-Hal with sodium cyanide? Perhaps other cyanide salts will work in a similar way, maybe using
ferrocyanide/ferricyanide? So long as the Fe ion is not halophilic a nitrile may be formed, otherwise its an isonitrile or no reaction.
[Edited on 28-1-2009 by DJF90]
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panziandi
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CuCN is used to convert Ph-Br to Ph-CN
NaCN or KCN is used to convert R-X to R-CN
AgCN is used to convert R-X to R-NC
I haven't seen or heard anything about ferro/ferricyanide being used. I would imagine that the CN is so tightly complexed to the Fe that it wouldn't
be able to react under standard conditions. IIRC hot conc acid is required to liberate HCN from these salts so I would imagine a poor reaction with
R-X compounds.
Aldoximes are easily formed from hydroxylamine and an appropriate aldehyde. Dehydration of these aldoximes gives rise to nitriles. Wikipedia (with no
references given specifically for this reaction) states aldoximes can be dehydrated with triethylamine/SO2, also by zeolites and by sulphuryl
chloride. http://en.wikipedia.org/wiki/Nitrile#Synthesis_of_nitriles
* Zeolites are easily obtained, Sulphuryl chloride is obtainable or could be made, triethylamine and SO2 are fairly easy to get.
I found this paper Ping Yan, Patrice Batamack, G. K. Surya Prakash, and George A. Olah, Catalysis Letters Vol. 101, Nos. 3–4, June 2005
p141 which describes a method of dehydrating aldoximes using gallium (III) triflate. Well if you can obtain triflic acid and gallium metal one
could make the catalyst themselves. Yields reported in the 80-100% range!
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