04-14-02 19:12
No 296836
This is a summary of my recently experiments with catalytic hydrogenation under pressure (5-8bar) with a Parr shaker.
The starting material was benzylnitropropen (made by condensation of bensaldehyde and nitroethane in AcOH with cyclohexylamin as the catalyst)
Several experiments was made
Ex. 1 1g of Nitropropen was disolved in methanol with 50mg Pd/C, the hydrogen uptake was fast the first two min. and then it stopped. Took the bottle off after 1 hour, yield 900mg of the oxime
Ex. 2 1g Nitropropen disolved into AcOH and shulfuric acid, again I got the oxime
Ex. 3 1g nitropropen disolved into a mixture of HCl(g) and MeOH, more oxime.
Ex. 4 1g nitroproPAN (made with NaBH4) disolved into MeOH with 3%HCl(aq), eaven more oxime.
Ekes 4. Now with trimethoxynitroethan MeOH and HCl(g), more oxime and some crap.
Ekes 5. Now with RaNi as the catalyst. And again, the oxime was made in a good yield.
I surely hoped on better results from cat. Hydrogenation.
Inspired from the litt. A very high Cat. Load should do the job (1g to 1g) but that was not my goal.
A dam good book about Cat. Hydrogenations is: (thanks LabTop)
Hydrogenation Methods. (Best synthetic methods), Rylander, Paul Nels. Academic Press. ISBN 0-12-605366-9.
Printed in GB by St Edmundsbury Press Limited, Bury St Edmunds, Suffolk.
It states that reduction og nitropropanes and propens is hard to doo (high pressure >500psi or a lot of catalyst. Usual moderate yields)
Conclusion, I will now move on to the electro reductions, that might bee the grail
(Stranger)
04-14-02 21:18
No 296865
About 30 years ago, I did a semi-legitimate study of this matter. The results were thus: Nitro-Propenes hydrogenate
to Oximes, Nitrostyrenes may, according to Spath, be hydrogenated to primary amines (as he claims in his mescaline synthesis). The only reference to claim success
at reducing nitropropenes to amines Was a very high pressure
and temperature reduction over Raney/Nickel catalyst/ In
a solvent saturated with ammonium acetate. My premise is,
that these conditions didn't actually reduce the nitropropenes to amines either, at least not via reducing the Oxime. Rather, the solvent converted the oximes to hydroxylamine acetate, and iminoketones that were formed by the resulting free ammonia were then catalytically reduced to amines. Naturally you know, that steam distilling those
Phenyl-2-propanone Oximes from acid solution will produce
Free Phenyl-2-Propanones. So, you actually have already achieved your goal. Now I expect, in your moment of triumph,
with the alchemical process complete. You will renounce all worldly ambitions, dispose of your product, and go out into
the forest to seek enlightenment. It doesn't get any better
than this. You have learned how to work with hydrogen, you
have become the most elite of Bee's. Have you considered, that it might be time for a new kind of adventure?
(Stoni's sexual toy)
04-22-02 13:55
No 300143
hest, I think I saw a ref in that Rylander book a few years ago which used conc HCl as the solvent, and 20 bar of H2. Could you please have a look for us?
I'm not fat just horizontally disproportionate.