High Bees!
Swim needs once more the opinion of more experienced bees, to find out what he´s done wrong..
Goal was the reductive amination of P2P with Methylamine.HCl and Al/Hg. The procedure is described here:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/p2p-meth.html
Here is what was done:
19,5g of thick aluminium foil was cut into ~2x2 cm and placed into a wide mouth erlenmeyer flask. The aluminium was covered with a solution of 500mg HgCl
2 in warm water.
Stirring wasnt easy with the magnetic stirrer, so the flask was swirled from time to time. After 30sec the solution turned grey and hydrogen envolved at a steady rate. After 1 more minute the HgCl
2 solution was decantet, and the aluminium was washed with 2x 500ml of cold (tap) water.
Then there was added in the following order:
32g of MeAm.HCl (prepared via ammonium chloride/paraformaldehyde an recrystallized from IPA - it was still a bit wet from IPA so more was used) in 30ml of warm tap water.
~ 75ml of Isopropanole
~70ml of 25% NaOH solution [Note 1]
and finally 20g P2P dissolved in 175ml of IPA (P2P that was prepared in
Post 473189
(Xicori: "P2P-Success! (Phenylacetic acid/AA/NaAc)", Stimulants))
Great amounts of Hydrogen envolved from the aluminium surface and temperature rose. The flask was cooled from time to time in a water bath to keep temperatures below 45°C. The most exothermic part of the reaction was over after ~ 5 hours.
At first a grey sludge settled at the bottom, but the colour changed to a brownisch/grey after some hours.
After 5 hours all aluminia foil was consumed, and tha flask was stirred for additional 10 hours at room temperature.
Then again 50ml of 25% NaOH was added what caused some (but very little) bubbling.
After everything settled to the bottom of the flask the clear orange liquid was decanted and the residue was washed 3 times with 100ml of IPA.
The washings were combined, and the solvent was removed on the rotary evaporator.
The residue was poured into 700ml of water and conc. HCl was added until the pH was 1-2. After a lot of stirring (a lot od organic material didnt dissolve in the acidic water) the solution was washed 3 times with 50ml of DCM.
The DCM extracts were orange in colour while the aqueous phase was now nearly colourless.
The aqueus phase was basified which caused a lot of solid material (i think Al-Hydroxides) to fall out of solution. (I think that souldn´t happen at that stage?!)
The basified mixture was extracted 3 times with 80ml of DCM, but extraction was very hard (Emulsions because of the salts that floated around).
The combined extracts which were very slightly brownish were washed once with water and then dried over sodium sulfate.
The solvent was removed on the rotary evaporator to leave about 2-3ml of dark brown oil (
). This amount wasnt enough for distillation so it was suspended in acidic water, but some of the oil didnt dissolve, even with excessive shaking.
So it was washed once more with 15ml of DCM, and the (colourless) aqueous phase was evaporated under vacuum on the rotary evaporator to leave a purple(!!) amorphous solid (a very little amount)
Does ynone has any ideas why this failed? i dont wanna perform this reaction until i know what my error was, because swims amount of ketone is a limiting factor...
Maybe the procedure isnt the best one...? - it sounds strange to add all the NaOH solution at once to the Al/Hg, etc... did anybee have success with this method?
Note 1: maybe a bit too much NaOH was added at that stage, may this have caused the error?
I´ll hope to find out the reason with your help!
Best wishes,
xicori
Edit: I´m sorry, i think that sould belong to the Stimulants forum