Since his last experiment wasn't very successfull, SWIM decided to try once again to reduce P2NP to amphetamine directly via Pd/C and ammonium formate as hydrogen donor. Not wanting to waste any more of his P2nP (it was his 3rd try with this route
), SWIM tried to follow the instructions in
Post 108528 (missing)
(dormouse: "reduction of P2NitroPropene with Pd-C -dreamer", Novel Discourse)respectively
https://www.thevespiary.org/rhodium/Rhodium/chemistry/nitropropene.cth.txt
(using exactly same ratios, solvents etc.), at least as closely as it would be possible (he had no chloroform at hand, but tried to substitute it with DCM, which should work, not enough GAA, so he dedicded to use iPrOH as co-solvent, and he slightly modified the workup). Here is what he did:
First, SWIM weighed out 4,4 grams of Pd/C (10% Pd, used one time and reactivated like described in
Patent US3214385
.
The Pd/C was put in a 500ml RBF, moistened with iPrOH, then 40 ml AcOH (last try was with some formic and mainly produced loads of CO
2 smoking from top of his condenser
), another 100 ml iPrOH and 20 g "relatively pure" P2NP (nice yellow crystals, not the bright yellow ultrapure type, but they would be still good enough, SWIM thought) were put in, together with ~3g silica gel.
SWIM then heated to reflux (ca. 100°C). As soon as reflux started, he introduced 3x 13g NH
4COOH every 9 minutes and one last extra 5g portion was introduced after 25 minutes. After 35 minutes, SWIM cooled everything, added ~100ml DCM and set up for gravity filtration. (AAARGH!! It took 3,5 hours!
SWIM WANTS VACUUM!)
Then he added water until the DCM separated out nicely (~500ml). The DCM was separated, distilled away and SWIM got 11,7ml of a yellow oil with a VERY distinctive smell
. "Hmm, dreamer got more than 4ml more, but still ok" SWIM thought and proceeded with preparing 200ml of dilute (15%) HCl and saturated NaOH solution. Next, he dissolved his oil in 15% HCl, washed 3x with DCM (lots of red something were removed), basified carefully to pH > 9 and extracted with toluene twice. He then combined the toluene xtracts and washed them with saturated NaCl soln. The toluene lost its dirty appearance and became clear, but still colored.
Because SWIM always wants to be accurate, he decided to carefully distill away the toluene for being able to determine the amount of freebase, but unfortunately he ended up with just 3,3ml of a clear, yellow oil, pH of aequous soln. was 5-6 and it dissolved it HCl... and had THE SMELL..
Since his last attempts in forming the sulfate had failed miserably (got
nothing..), he tried to be very careful this time. He thought "Hm, for a 4M solution, I would need to dilute 4,93ml of my oil to 10ml with iPrOH, assuming it was pure amine freebase. Ok, some toluene may be still in it, so I will use 0,6ml and dilute to 1ml and assume it is 4M concentration. And the sulfate is (C
9H
11NH
2)
2*H
2SO
4, so I should be able to neutralize my 4M with an equal amount of 2M sulfuric/iPrOH, or at least not over-acidify everything". Said, done. SWIM diluted his oil in a test tube, added calculated amount of acid soln. - CLEAR YELLOW...
"Bad, too much acid perhaps" SWIM thought and poured everything back into his oil (3,3ml total, to remember). And guess what, white precipitate formed! "Hmm, freebase is definitely not pure, calculations were wrong or sulfuric soln. was somewhat "wrong" (prepared a few days ago by mixing 54,4ml 98% H)
2SO
4 with 45,6ml 99,9% iPrOH and drying with silica gel)" SWIM thought, and added a bit of abs. ether (for better precipitation, to reduce solubility of formed sulfate) and put it in the freezer for 10 minutes.Then SWIM filtered the crystals and washed with ether and then 99,9% acetone.
But he only got 150mg of white (very pure) sulfate!
Perhaps I should have dried my solvents with some drying agent, SWIM thought disappointed as he was drying his crystals. Or perhaps I should'nt have distilled off the toulene, perhaps there was still water present, and the freebase was steam distilled, but then, crystal formation should've been easier (nearly anhydrous conditions)
Can anybody help SWIM in improving his shitty yields (1%!?
)
He would greatly appreciate it!
Thanks A