CRN114-Discriminator
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Help Isolating Ethylamine
So after performing the delepine on ethyl bromide, I was intent on recycling the bromide salt. Long story short, I have a flask with sodium chloride
and ethylammonium chloride. I have boiled off the alcohol. While attempting to remove the water (vacuum pump is out of order) I get to a point where
the system is behaving as though it is super saturated with salt and the water isn't wanting to come off. So after other experiments where such a salt
saturated solution simply produced a two phase mixture when an alcohol was added to crash it out. I decided to use acetone. May I now add that I have
been suffering from insomnia for months to explain my brain fart... not realizing that I was creating an imine and all... So I have removed the
acetone (as well as more water) and more of a salt has precipitated. The question is: is it most likely the sodium chloride (I could do a flame test)
or could the imine have precipitated? Then, I have read that imines are liable to hydrolysis, is it more likely that the reaction reversed and the
removal of the acetone drove that forward or is there something that I should do to get it back into the free amine form? There is a dark red cast to
the solution. What is most likely contributing? The idea was to isolate the salt (ethylammonium chloride) I am now thinking that perhaps boiling off
the free ethylamine and then neutralizing the resulting solution would have been better. Feeling a little stuck. Any friendly advice would be welcome.
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Melgar
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I suspect that there's formaldehyde in there that wasn't entirely removed in the hexamine hydrolysis step, but that's more what I'd expect from myself
if I had that problem. You may have done everything perfectly up until the part where you started telling us what you did.
I've looked into ethylamine preparations in the past, and the one that seemed easiest was probably calcium propionate -> propanoic acid ->
ammonium propanoate -> propanamide -(Hoffman rearrangement)-> ethylamine. But that's just for if your current endeavor ends with you dumping
everything down the drain.
You very likely have produced one of the compounds mentioned in this thread:
http://www.sciencemadness.org/talk/viewthread.php?tid=228
Many of them readily condense with amines.
The first step in the process of learning something is admitting that you don't know it already.
I'm givin' the spam shields max power at full warp, but they just dinna have the power! We're gonna have to evacuate to new forum software!
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CRN114-Discriminator
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It seemed like the delepine was easier to do at scale than the hoffman. I have a patent (somewhere in my collection of them) talking about using the
relative strength as bases to separate ethlyamine from di and triethylamine. In terms of scale, that also seems attractive. I am wondering if the
delepine would still be viable had I basified and boiled off the free amine. Maybe I will just go ahead and try that now. Yeah I am about to the point
of a botched experiment with the subsequent dumping. Hence the whole "registering and posting" vs my normal m.o. of simply lurking.
At any rate, do you think that the amount or type of acid used has much bearing on the side products produced? Thank you for the prompt response. I
have always had a warm and fuzzy feeling for this community, just hadn't had anything that I wanted to say until now.
[Edited on 11-15-2018 by CRN114-Discriminator]
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CRN114-Discriminator
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I hate when I do searches and the experiment just kind of peters out. In that interest, I wanted to post a follow up. Really I wanted to post a follow
up with solid % yield data, but.... my receiver was not as secure as I intended.. So some got spilled. It was still evolving. So I hooked it back up.
I just won't ever know exactly how much I got (or would have.) What I can say for sure is that by running in a slight excess over theoretical of a
NaOH solution and then by slowly boiling said solution, I was able to obtain an easily condensable gas that smelled strongly similar but distinct to
ammonia.
So the short answer is that EtBr -->Ethylamine via the Delepine does seem to have some viability. I will work on tweaking it further and will
report back, but in the meantime, there you go.
The setup was a 1Lrb with a 2-neck claisen. Addition funnel in one neck and a 300mm? vigurex column in the other. Attached to that was a gas adapter
with a stopcock. PP tube going into a clean sake bottle, submerged in salt/ice.
It took a while for any gas to start coming off. I am bubbling it into H2O. I thought that the amine would retard freezing more quickly. I get the
feeling that running it into a flask, itself in salt/ice or dry ice acetone, with a dewar as the outlet, I think that you could probably just condense
it. Though it probably will be rather wet.
Like I said, just figured a follow up was in order. Plus talking to you guys did surprisingly help with the slight rage of the spill. Its just so much
time and energy that you are really cleaning up. Little by little, I suppose.
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