Author Topic: Leuckart-Wallach Rxn Time Clarification  (Read 1448 times)

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grellobanans

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Leuckart-Wallach Rxn Time Clarification
« on: August 07, 2003, 11:20:00 PM »
There are many different temperatures and corresponding lengths of time to perform this reaction. However, swim is wondering why not just wait until the bubbles cease? When the CO2 evolution stops, doesn't that mean the reaction has gone to completion? Swim is just wondering because 5 hours have already passed at 140-160C and the bubble formation is still occurring. If swim stops it now, what if the reaction isn't completely done yet?

Also, swim used some formic acid in the mixture too and for some reason only a few drops have distilled over. What goes in should come out??? What's going on here? the temperature is way above where formic should come over.

grellobanans

  • Guest
Continued
« Reply #1 on: August 08, 2003, 06:24:00 AM »
Swim continued the reaction for another 5 hours because the CO2 evolution was still vigorous. Turned off heat, and swim wasn't paying attention as it cooled and found that the color had changed from the nice light tan brown to a darker grey! Contents were quickly poured into a sep funnel and 200ml water was added and the brown color started to separate out again. The other layer is a dirty greyish white with hint of yellow? Swim is just adding all these details for other bees in the future.

Oh yes, the amounts used were: 130ml formamide, 50g mdp2p, 60ml formic acid.
Swim is still wondering why the majority of the formic acid did not distill. Did it convert to something else?
Next step is the hydrolysis.
Swim will use 60g KOH, 200ml EtOH, 50ml H2O for 30 min. No A/B will be done, but freebase will be distilled.
This reaction is definetely easier than those for MDMA, and good for ppl who don't have access to hydrides and such.

grellobanans

  • Guest
Update
« Reply #2 on: August 18, 2003, 05:56:00 AM »
Hydrolysis was done for 30 mins at 80C. Freebase was extracted with DCM, DCM distilled off and freebase distilled between 80-120C (vac isn't very constant). About 20 ml (a rough guess by eye) of water white oil came over. The smell was slightly ketoney, so swim suspected lower yield. Gassed with moderately dry HCl in 200ml dry DCM and 200ml dry acetone. 3 gas passes were done, very white fluffy precipitate. Total yield after recrystallization in IPA/Acetone was ~11g. So there was most likely a lot of unreacted ketone from the first step.