When doing reduction of MDP2P it's common practise to use Nitromethane to make Methylamine in situ. Ref. Ritter's write-ups.
Can you do this with Meth via hg/al reductions?
Can you do this with Meth via hg/al reductions?
Found this, and suggests Hg/Al reducing nitromethane to Methylamine gas which will dissolve in the methanol. On small scale <50g of ketone, is there any reason we can't drip the ketone with the Nitromethane and reduce both, getting methylation in situ.
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Stage 1: Making Methylamine In Methanol Using Nitromethane And Al/Hg
Processing 1 mole of ketone will require 2.5-3 moles methylamine dissolved in methanol as follows:
Procedure
Cut 162g aluminium flashing into small squares and place in a 2 neck 2L, or ideally 3L flask with 1500mls methanol and add 0.5g HgCl to amalgamate. Let amalgamate for 5 –10 minutes.
Mix 54mls water with 183g (162mls) nitromethane in addition funnel and add 100mls methanol to form a solution.
Then pour in about 30mls of this nitromethane mixture into the reaction flask and let it heat up until refluxing.
This will cause a vigorous reflux, then slowly drip the remaining nitromethane mixture in until it is all gone, this will take about 30 minutes or more.
Ideally place a hose from the reflux condenser to a 10-30% HCL bubbler solution to stop escaping methylamine gas from stinking the lab out.
Stirring isn’t really needed, just occasionally swirl the flask by hand to help break up the aluminium sludge.
Let reflux for about an hour until the reaction cools and reflux stops. Then add 200ml cooled 50% NaOH solution. This will start another vigorous reflux for an hour or so.
NB: The NaOH helps finish the reaction, breaks up the aluminium sludge and then forces the methylamine gas out on heating.
When reflux stops, change the glassware setup for distillation. Place hose from vacuum outlet on the bent receiver to HCL bubbler to again stop lost methylamine gas from stinking your lab out. Care should be taken to stop any suck backs.
Turn on the hotplate and distil the methanol with methylamine from the reaction flask until the stillhead thermometer reads around 80-90DegC. This ensures all of the methylamine and methanol has been recovered and there should be around 1400ml in the receiving flask with a small amount of elemental mercury at the bottom.
Don’t heat until completely dry as the sludge will heat up and smoke.
Wash the hardened sludge residue from the distillation flask with warm water.
The distilled methanol should now contain enough methylamine to animate well over 1 mole Ketone.
Ideally titrate a small sample of methanol/methylamine solution to neutral with 10% HCL to work out exactly how much methylamine is recovered.
I normally find I get a 6% methylamine solution. This means I have almost 3 moles methylamine recovered in the methanol, which is perfect for the next step.
Time to this stage is around 5 hours"
"
Stage 1: Making Methylamine In Methanol Using Nitromethane And Al/Hg
Processing 1 mole of ketone will require 2.5-3 moles methylamine dissolved in methanol as follows:
Procedure
Cut 162g aluminium flashing into small squares and place in a 2 neck 2L, or ideally 3L flask with 1500mls methanol and add 0.5g HgCl to amalgamate. Let amalgamate for 5 –10 minutes.
Mix 54mls water with 183g (162mls) nitromethane in addition funnel and add 100mls methanol to form a solution.
Then pour in about 30mls of this nitromethane mixture into the reaction flask and let it heat up until refluxing.
This will cause a vigorous reflux, then slowly drip the remaining nitromethane mixture in until it is all gone, this will take about 30 minutes or more.
Ideally place a hose from the reflux condenser to a 10-30% HCL bubbler solution to stop escaping methylamine gas from stinking the lab out.
Stirring isn’t really needed, just occasionally swirl the flask by hand to help break up the aluminium sludge.
Let reflux for about an hour until the reaction cools and reflux stops. Then add 200ml cooled 50% NaOH solution. This will start another vigorous reflux for an hour or so.
NB: The NaOH helps finish the reaction, breaks up the aluminium sludge and then forces the methylamine gas out on heating.
When reflux stops, change the glassware setup for distillation. Place hose from vacuum outlet on the bent receiver to HCL bubbler to again stop lost methylamine gas from stinking your lab out. Care should be taken to stop any suck backs.
Turn on the hotplate and distil the methanol with methylamine from the reaction flask until the stillhead thermometer reads around 80-90DegC. This ensures all of the methylamine and methanol has been recovered and there should be around 1400ml in the receiving flask with a small amount of elemental mercury at the bottom.
Don’t heat until completely dry as the sludge will heat up and smoke.
Wash the hardened sludge residue from the distillation flask with warm water.
The distilled methanol should now contain enough methylamine to animate well over 1 mole Ketone.
Ideally titrate a small sample of methanol/methylamine solution to neutral with 10% HCL to work out exactly how much methylamine is recovered.
I normally find I get a 6% methylamine solution. This means I have almost 3 moles methylamine recovered in the methanol, which is perfect for the next step.
Time to this stage is around 5 hours"