Methylamine by catalytic hydrogenation of nitromethane

by KrZ

Procedure

Into a Hydrogenation vessel was placed the following;

  • 3500ml Nitromethane
  • 12500ml MeOH
  • 25g Pd/C 5%

The vessel was stirred with a 3.75" stirbar, 1200rpm. The atmosphere was evacuated with vacuum, and the vessel was pressurized to 80psi with H2. The vessel was left unattended with the self-adjusting pressure gage attached for 120 hours. At the end of this time, the vessel was shaken to remove any Pd/C that might have managed to kling to the side and dried there. The H2 was then vented outside, with the pressure release valve. The remaining H20 was vacuumed from the pump with the output hose of the pump draped out the window. Atmosphere was then allowed to enter the inside of the vessel. 1L of the reaction mixture was filtered through celite twice to remove the suspended Pd/C. To this was added 300g of anhydrous MgSO4, the mix was stirred for 15 minutes and then filtered to remove the MgSO4 (Wanted to use NaSO4 but someone said it wouldn't work as well, true?). The 1L was then placed in a 2L RBF and stirred, when vacuum was applied considerable bubbling was noted, once the bubbling subsided the mixture was then distilled, when the MeOH fraction was complete there was nothing in the flask, nothing!!! The rest of the reaction mix was then filtered through celite, dried with MgSO4, and used as it was, still with a bit of a charcoal tint, but nothing to interfer with the unholy scale aminations that came next.


And another one...

  • 2500g CH3NO2
  • 3000g CH3OH
  • 20g Pd/C 5%

They were stirred and hydrogenated at 80psi, after 24 hours the heat subsided, and at 48 hours H2 uptake had long since ceased and the reaction was shut down. On depressurization, the ammonia-like odor was definitely evident. The catalyst was vacuum filtered off and collected, and the remainder still had a definite charcoal look to it. Filtering this through celite took care of most of that. The mix was split in half and each half sat with 1500g of Na2SO4 for an hour, with occasional stirring. The Na2SO4 was filtered off for a long time, until it was quite dry in appearance, the halves were combined and washed 2x with 1L of CH3OH, which was filtered off and added back to the solution. What was left was about ~7.5L of good loving. When 1L of this was converted to the HCl salt, 250g of salt was collected.