andre178
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Registered: 11-12-2009
Location: San Diego, CA
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hydrogenation
Being a novice chemist, I heard that hydrogenation is a dangerous process for first timers, as you have to flush with nitrogen and make sure your
experiment is void of air.
I'm working on making a small scale synthesis of ethidium bromide via the paper I attached by De Nobrega Bastos and Mahler.
My question is out of caution, the part that I'm most worried is bubbling H2 through a fitted flask for 40 minutes. The reaction vessel is very small,
the catalyst is 0.2 g platinum oxide. The solvent is acidic ethanol 5ml. All this is done while maintaining reflux.
Do I need to take the typical hydrogenation precautions for this experiment and flush out the reactor, or just slowly bubbling it through for 40
minutes will be okay?
Attachment: de nobrega.pdf (372kB)
This file has been downloaded 641 times
[Edited on 2-23-2011 by andre178]
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smuv
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I wouldn't worry too much. PtO2 in and of itself is not too prone to fires, what happens is in situ it is reduced by hydrogen to platinum black which
is the active catalyst.
That being said, I think you could get away just vigorously stirring the stuff under a balloon of hydrogen in a hydrogen flushed flask. I have found
PtO2 and 5% Pt/c to be quite active catalysts for the reduction of aromatic nitro groups at atmospheric pressure. I think the conditions in this
paper are really overkill.
Just a heads up, before you run the hydrogenation you should take care to have a very pure product. Hydrogenations are very sensitive to poisoning.
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