failed red. of p2np with zn / hcl

[josef_k]

I recently tried to reduce p2np with zinc. This is how I did it:

Into a 250ml erlenmeyer flask was placed 50ml ethanol, 16g p2np and 19g zn. The p2np and zn didn't dissolve, but the flask was swirled until they were finely divided. Then slowly 40ml of 30% HCl was dripped in, drop for drop almost, while the flask was swirled. When the flask got a little hot, it was put into a cooling bath. It was aimed to keep it at about 30C. After all the acid was dropped in, there was still some lumps of zinc left on the bottom, fissing. Probably swirled the flask to little. They were left fissing for an hour. Now the solution was yellow. It was poured into a sep funnel, without the unreacted zinc. 60g NaOH in 200ml water was added. At first much ZnOH precipitated, but after all NaOH was in, most had dissolved again, and there was an yellow/orange oily layer on top. This was separated. It weighed 13g, but was probably unpure. No distillation equipment was had, so the oil was just dissolved in some isopropanol, and 4g of 98% acetic acid was dripped in. This didn't produce any crystalls at all, even after some hours in the freezer.

Some questions:

1. Can't you make amphetamine acetate how I attempted to do it?

2. Was the orange/yellow oil layer really amphetamine?

3. Has anyone got any tips?

[raffike]

First measure pH of your amphetamine solution,if neutral or acidic evapp,if basic add some more acid.
You probably have amphetamine acetate.Evap alcohol and rxtal,your product is in alcohol if there is any but i'm pretty sure you have at least some as it separated from rx mix.Often it doesn't just jump out of solvent especially if it's bit impure.I'm not sure which solvent would be good for rxtalling.You should have converted it to HCl salt but acetate should be stable and eatable aswell,just evapp(don't overheat it) and come back with results.

[GC_MS]

P2NP = phenyl-2-nitropropene?

If yes, it is not surprising your hoped reaction does not work. The Zn/HCl reduction does work for nitroethenes, for instance in the reduction of 3,4,5-trimethoxy-nitrostyrene or 2,5-dimethoxy-nitrostyrenes. I can personally testify it works for 3,4,5-trimethoxy-NS. However, this type of reduction does NOT work for nitropropenes! It will give you a combination of the aimed amine (in very low yield) and the ketone (in your case, P2P). There is some information on Rh's site on this topic, and I'm sure you can find even more using TFSE. It worked for me when I needed it. Here is a start:

Post 245040

(Rhodium: "O Leminger's Phenethylamines - posted by Karel", Novel Discourse)

[Barium]

The yellow/orange oil should at least have been purified by a simple acid/base extraction. Then you would at least have known if some amine had been formed, which is very unlikey with this method.