numos
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Ethylene thiourea
Found this procedure on Orgsynth a while back. It's simple, the chemicals are pretty easy to get and I though it was great practice as a beginner type
synthesis. It basically involves dripping Carbon disulfide on Ethylenediamine and Ethanol. The procedure states the initial addition of Carbon
disulfide is violent and may need to be cooled, it may be that this was due to the larger scale, but I never observed a violent reaction during any
step. about halfway in, the Carbon disulfide bubbles as soon as it hits the mixture below, while initially it sinks to the bottom and has to be
stirred. Which is another point, the procedure doesn't mention this, but I found having a stir bar going helps, the powder tends to cake up at the
bottom, and may cause bumping, the stirring eliminated this. Final point, at one point it says to reflux for 9-10 hours. I cut mine short after 2
hours (entire synthesis took 5-6 hours as opposed to 12-13 hours) and as a result the purity suffered quite a bit. They mention the extensive heating
is there to neutralize non-cyclic acids, the test being no precipitate forms when added to Copper sulfate solution, and the product I made did form a
green precipitate indicating impurities.
http://www.orgsyn.org/demo.aspx?prep=CV3P0394
Also, the procedure didn't mention, during the duration of the procedure, Hydrogen sulfide is constantly liberated. Despite a fumehood, it became bad
to a point where installing a scrubber was necessary, I suggest just starting with a scrubber.
Initial reactants (I used 1/10 scale of procedure
Product starts crystalizing after about 50-80% of Carbon disulfide has been added
Waiting for the flask to cool
 
I started with 13.3mL (12.0g) of Ethylenediamine and the final product was weighed at 18.4g. This is the first time I calculated percent yield for an
organic reaction, however if I did it correctly it should be ~90-91% yield. It looks like a lot here, but it's a very fluffy and light powder.
I did a melting point test, but it was done with a beaker of canola oil and a pippet tip as a capillary tube, so I can't really vouch for accuracy.
However the powder started to melt at 194oC and finished melting at 196oC, as opposed to the actual 203oC. (according to Wikipedia) I don't know if
that's good or bad, but there it is.
Edit: I just checked back at the Copper sulfate solution. I was mistaken, there is no precipitate, the solution is green indicating some reaction, but
perfectly clear. I'm guessing it's still not as pure as it could have been, had I boiled 6 hours further.
[Edited on 7-6-2015 by numos]
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Metacelsus
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How did you get the carbon disulfide? Did you make it?
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numos
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Making it seems like a lot of work for a rather inexpensive chemical. I bought a bottle of 250mL for $20, shipped directly to California. The label is
mine, because it came with a crappy label. 
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The Volatile Chemist
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Nice work! The starting compounds don't look too bad, and the final product certainly is an interesting compound. Is it possible to recrystallize the
product?
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Boffis
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@numos, nice work and an interesting heterocyclic.
Do you have any plans for it? Does it for instance react with alkyl halides like thiourea does to give thiuronium salts? And from there to ethylene
guanidine or aminoguanidine via its reaction with ammonia or hydrazine respectively?
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numos
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I have not found a solvent that can dissolve an appreciable amount of it. I tried water, Acetone, Methanol, Toluene. It does not dissolve in any of
those except water, and even that is almost nothing, 2% according to Wikipedia. I have yet to try elevated temperatures, as it may be promising with water.
Quote: Originally posted by Boffis  |
Do you have any plans for it? Does it for instance react with alkyl halides like thiourea does to give thiuronium salts? And from there to ethylene
guanidine or aminoguanidine via its reaction with ammonia or hydrazine respectively? |
Unfortunately I don't have any haloalkanes right now, and have not taken any chemistry above AP chem offered at our school, and as much as I hate it,
I do not have the knowledge to predict this kind of reaction. But you have given me ideas of what to do with it, so reaction with haloalkanes will be
my plan for it. 
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The Volatile Chemist
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I would be curious as to if the mechanism of this reaction works for substituted ethylene diamine, or even substituted CS2. I doubt it, I'm just
postulating, but still...
Does it do any fun complexing, with, say Iron(ii or iii)? Just curious.
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clearly_not_atara
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Unfortunately it appears that CS2 does not react with secondary amines, which means you'd need to try thiophosgene or something like that. It might be worth the effort:
tetrasubstituted thioureas have comparable ligand properties to triarylphosphines. I don't know if there need to be aryl substituents for them to work
well, but it would be interesting to see how they act. See e.g:
http://onlinelibrary.wiley.com/doi/10.1002/ejoc.200300543/ab...
Of course, if we could just figure out how to alkylate [ethylene] thiourea, that would probably be easier! Maybe a Ullman/Goldberg reaction of sorts
will work with a halobenzene and CuI? That could give you N,N'-diphenyl-N,N'-ethylenethiourea.
The thioureas also generate photosensitive mixtures with silver (of course!):
https://www.google.com/patents/US4749646
[Edited on 10-7-2015 by clearly_not_atara]
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The Volatile Chemist
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Cool! Too bad about the secondary amines, but I was just talking about making interesting rings with primary amines other than Ethylene Di-amine.
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