497
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Ethyl Isocyanate
How would this be synthesized? I have searched quite a lot and come up with very little. Methyl isocyanate is mentioned more frequently, but I have no
use for it. The closest thing I could find from chemical suppliers was chlorethyl isocyanate. I'm not sure if that could be converted to ethyl
isocyanate or not.
[Edited on 22-3-2008 by 497]
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MagicJigPipe
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After some really quick research it seems you would need isocyanic acid which can be made by reaction of potassium cyanate and formic acid. Potassium
cyanate can be had from potassium carbonate and urea.
Since ethyl isocyanate is just an ester, acid catalyzed esterification with ethanol might work. Maybe, someone with more knowledge could elaborate on
the above syntheses and esterification?
"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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microcosmicus
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According to "Laboratory Manual of Organic Chemistry"
by Harry L. Fisher (experiment 31, p. 122),
you can produce ethyl cyanate by heating equal parts of
dry potassium cyanate and dry potassium ethyl sulphate.
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MagicJigPipe
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I believe he wishes to obtain ethyl ISOcyanate which, I believe, has very different properties. Also, won't potassium permanganate oxidize cyanides
to cyanates? If so, in theory, acetonitrile could be oxidized to methyl cyanate? Obviously, that is nowhere near the compound he wishes to obtain,
I'm just speaking out of my ass. I shall stop now.
"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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Nicodem
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Please do not mess up this thread with so many missinformations! The original poster clearly stated the correct name of the target compound (EtNCO),
yet he failed to show much effort in searching the literature (so I'm moving this to Beginnings).
Ethyl isocyanate is prepared from ethylamine and phosgene (or phosgene prepared in situ from triphosgene). There are also other methods. The
SN2 substitution with cyanate anion results in mixtures of alkyl cyanates and alkyl isocyanates (isocyanates can prevail, depending on the nature of
the electrophile and solvent).
Read also: http://en.wikipedia.org/wiki/Isocyanate
PS: Do not mess with such volatile isocyanates unless you know what are you doing. You seem too young to remember Bhopal.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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MagicJigPipe
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I'm sorry, CYANIC acid can be made via a potassium cyanate and formic acid. But, of course, that is not needed. I apologize for the mistake.
Here is a patent describing another route to alkyl isocyanates
http://www.freepatentsonline.com/4354979.html
Nicodem, what exactly were you referring to as misinformation? Seems strongly worded for an honest mistake by either microcosmicus or myself.
"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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JohnWW
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Methyl isocyanate was the stuff which, on leaking from the now-closed Union Carbide plant at Bhopal, India, which made fertilizers and pesticides,
killed thousands of people in and around that city about 20 years ago. Of course, India's lax regulatory régime regarding environmental, occupational
health and safety, and plant maintenance matters, enabled that disaster to happen. Union Carbide probably made it from CH3NH2 + COCl2 -> CH3-N=C=O
+ 2HCl.
That being the case, what do you want ethyl isocyanate for? As well as being highly poisonous, organic isocyanates are also explosive, like azides.
They are also reacted with alcohols to make urethanes (carbamates), and these polymerized to polyurethanes for synthetic foams and varnishes.
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Nicodem
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| Quote: | Originally posted by MagicJigPipe
Nicodem, what exactly were you referring to as misinformation? Seems strongly worded for an honest mistake by either microcosmicus or myself.
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Sorry if my use of the phrase "misinformation" appeared like I was insinuating a purposeful act. That certainly was not my intention, but
unfortunately I don't know any English phrase for an "unintentional misinforming". It was in regard to posting guessing replies just for the sake of
posting something. Unfortunately, in most cases this results in bringing misinformation and confusion instead of the intended help.
Just imagine if it was you to ask a question and then would receive a misleading reply. If you would be lazy you could actually take someone's words
as granted instead of checking the literature. At the end, this might even result in hazardous situations and someone being hurt just because too lazy
to double check the information (this is just a hypothetical extreme example, unrelated to this thread).
JohnWWW, since when alkyl isocyanates represent explosive hazards?
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497
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| Quote: |
he failed to show much effort in searching the literature |
I searched quite a bit actually. Google comes up with about 10 hits, all of which are useless. I happen to lack a library of organic chemistry books.
Thank you for the information anyhow.
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Nicodem
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If you don't have access to physical libraries then search for references in the primary literature at publishers sites (ACS, RSC, Elsevier, Thieme,
etc.). Most publishers have very good search engines. You can then always ask for the full papers in the References section. There are several posts
with exact instructions on how to do the literature search even without the access to Beilstein or SciFinder. Also, when you try with google it is
always best to use the "google scholar" filter option so that you don't waste time with irrelevant hits.
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unionised
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Is the reaction of phosgene and an amine general? Does it work with ethylamine?
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Nicodem
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It is general only under the condition that the alkyl amine does not have any other functional groups that could react with phosgene and/or
isocyanate. However, it is not a particularly useful method for such volatile isocyanates as EtNCO. These require the use of pyridine for the
elimination of HCl from the intermediate carbamoyl chlorides (R-NHCOCl) instead of refluxing in toluene as can be done with the less volatile ones.
The attached paper describes such synthesis of EtNCO and reactions of amines with COCl2 in general. In the literature and patents, there are also
numerous other methods for preparing EtNCO that do not involve phosgene (thermolyses of carbamates, ureas and related Et-NH-CO-X compounds).
Attachment: The Preparation of Isocyanates, Carbamyl Chlorides and Cyanuric acid.pdf (495kB)
This file has been downloaded 891 times
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JohnWW
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Union Carbide's patent for the production of methyl isocyanate is at: http://www.freepatentsonline.com/3488375.html
See also http://en.wikipedia.org/wiki/Methyl_isocyanate .
About the Bhopal methyl isocyanate disaster in 1984:
http://www.bhopal.com/pdfs/browning.pdf
http://www.mindfully.org/Pesticide/2002/Methyl-Isocyanate-CA...
http://www.kerala.com/wiki-Methyl_isocyanate
http://en.wikipedia.org/wiki/Union_Carbide
http://papers.ssrn.com/sol3/Delivery.cfm/SSRN_ID752784_code4...
http://history1900s.about.com/od/1980s/qt/bhopal.htm
http://www.ielrc.org/content/c0408.pdf
http://list.jca.apc.org/public/asia-apec/1999-December/00137...
http://www.bhopal.net/oldsite/documentlibrary/survivingbhopa...
The Indian Government sued Union Carbide for $3 billion over the disaster.
http://proxyinformation.com/pdf/court04.pdf
http://bhopal.bard.edu/resources/research.php?action=getfile...
http://bulk.resource.org/courts.gov/c/F3/361/361.F3d.696.03-...
Here is a general patent for alkyl isocyanates, including ethyl:
http://www.freepatentsonline.com/3860623.html
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