Author Topic: NaBH4 is just amazing.  (Read 29675 times)

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  • Guest
NaBH4 is just amazing.
« on: September 30, 2003, 07:55:00 PM »
Cub ran his first NaBH4 reduction few days ago and found that this reaction is simply amazing.Only the dissolution of methylamine in methanol was bit complicated as methanol had to be constantly cooled during bubbling.Methanol was weighed before and after gassing and about 30 grams of methylamine had been dissolved in methanol.Added 80 grams of ketone(solution turned orange) and prepared an ice bath.Reduction took place in 1 liter round-bottom.Temp was kept below 15C with a bath filled with ice/NH4NO3 and everytime it dropped to 7-8C more borohydride was added which caused foaming and rise in temperature.Total of 14 grams of borohydride was used but when about 9 grams had been already added further addition didn't make temperature rise like it had been(probably all that there was to reduce was already reduced),still that 5 grams was thrown in and left solution to stir for 12 hours at low speed.Next morning cub discovered that colour of solution had turned to bright yellow(it was orange just after addition of ketone to MeOH/MeNH2).Solution was poured to sep funnel and added 1 liter of water and some 100 mls of DCM.Sepped off bottom layer and washed other one with some DCM.DCM and bottom layer was poured together.Evapped DCM to yield about 70 mls of almost colourless liquid with a distictive smell(little like methylamine or isosafrole glycol).Cub has never got such nice freebase from Al/Hg reduction.Freebase was dissolved in 600 mls of xylene and result was a colourless liquid.It was gassed and whoah,just like a toothpaste.Filtered at vacuum and gassed again,same result.Filtered and tested xylene to contain no more freebase(it was acidic).Bright white powder was rxtalled from acetonitrile(1 gr and 7 mls),dried.Yield was 70 grams of white powder that tasted quite bitter.This makes w/w yield nearly 90%,cub has never got such yield and purity with an Al/Hg reduction(w/w yields rarely exceeded 75%).NaBH4 is the shit,cub will never run an Al/Hg again.This was cub's first NaBH4 reduction and results are impressive.
PMK used was 96% pure confirmed by nMR(C13 and something else,sorry,cub knows nearly nothing about analysis,if needed could post some charts with some peaks,dunno how these are called),other 4% was safrole.
Borohydride,methylamine and methanol were all lab grade.
Special thanks to LabTop for posting such nice writeup(check rhodium site).


  • Guest
I was once also amazed by how easy it is to...
« Reply #1 on: October 01, 2003, 04:18:00 AM »
I was once also amazed by how easy it is to clean up the NaBH4 post reaction. It's much less messy and makes little if no emulsion. Even when using  al/hg with Aq. meam and reducing the al down to 1/3 of the nitro reaction, it still is a much cleaner post-clean-up process. Yield was only slightly less than what was achieved with al/hg/meam method.
Does anybody know if adding the aqueous MeAm to the methanol and stirring for 30 minutes with MgS04 actually removes the water in a ratio that keeps the amine in the MeOH? I read on here someone used a drying column with mgs04 + silica gel to remove the water. However I was with the understanding that the water is removed proportionally with the amine into the mgs04. Even Osmium mentioned this some 3 years ago. I did some research on his comment to follow up and it mentioned that mgs04 does indeed have a priority of what it absobs being water first, blah blah, and amines somewhere along the line.


  • Guest
cub has heard that some add silicagel to rx...
« Reply #2 on: October 01, 2003, 06:20:00 AM »
cub has heard that some add silicagel to rx mix in the beginning so that water would be removed as imine forms.Yet another thing to try,silicagel is very cheap anyway.


  • Guest
(Post deleted by technology)
« Reply #3 on: October 01, 2003, 06:54:00 AM »


  • Guest
Cub is not saying Al/Hg is bad,when he didn't...
« Reply #4 on: October 01, 2003, 07:03:00 AM »
Cub is not saying Al/Hg is bad,when he didn't have access to borohydride,cub ran some successful Al/Hg's also(45 grams of amine from 60 grams of ketone) but NaBH4 is just so foolproof and very high-yielding at the same time,if you use common sense,it's very hard to fuck up.Al/Hg,on the other hand,is very prone to fuckups,at least in cub's experiences...


  • Guest
How bad of me
« Reply #5 on: October 02, 2003, 02:48:00 AM »
what, so what you are saying moderator who ever you are, you are not allowed to speak your mind/opinion.. how wrong of me.. i am sure people can differ between you rating and mine.. chill out..


  • Guest
Self-rating is to misinform other users
« Reply #6 on: October 02, 2003, 03:34:00 AM »

Our rules

( reads as follows: "No offending, off-topic, crossposted, misinforming, or insignificant postings."

If you fake a certain rating of your post, then you are per definition posting misinformation, hence you became rated.

May I ask why you erased your post if you were so sure about you behaving properly?


  • Guest
I know the rules Rhod.
« Reply #7 on: October 02, 2003, 06:57:00 AM »
I know the rules Rhod. i did not want to offend anyone and i merely back up my opinion in my other post. Anyhow rhodium i rated it as a good read it was my OPINION not someone elses, therefore what is the problem..

it is not like i rated the post as good read on the original post.. if people cant read between the lines that is there problem..

as all i did was state my opinion which seems to have been neglected..

Tell me rhodium what is the difference if i had suggested it was a good read in my text.. would it be a diff story then? i ask.

Sorry for deleating do not wish to offend? and i still back my self up with a good argument... harmful intent meant... just opinion ;)


  • Guest
not quite
« Reply #8 on: October 02, 2003, 05:19:00 PM »
Anyhow rhodium i rated it as a good read it was my OPINION not someone elses, therefore what is the problem.

You didn't say it was in your opinion, you imitated a real rating text, which was very close to a real one.

Anyhow, please continue in PM if you have any further to say, as this is off topic.


  • Guest
Scale-up was performed.1 kgs of ketone,300-400
« Reply #9 on: October 13, 2003, 11:01:00 PM »
Scale-up was performed.1 kgs of ketone,300-400 grams of methylamine was dissolved in 4 liters of methanol and 100 grams of borohydride was used during reduction.An ice bath with ice/ammonium nitrate was used and it kept temperature within limits just fine.Borohydride was added over 2 hours.Left away to stir for 12 hours.Mix was flooded with water and extracted with 1,5 liter of DCM.DCM evapped to leave 1 kgs of raw base.300 grams of that base was gassed in 3 liters of toluene to yield 256 grams of white amine hydrochloride salt which means cub will get total of around 850 grams of amine salt out of that reaction,nice,nice indeed...
This all proves that NaBH4 is perfect for both large-scale and small-scale MDMA preparation.


  • Guest
66% Yield
« Reply #10 on: October 14, 2003, 02:33:00 PM »
1.00 kg MDP2P (178.2 g/mole) = 5.61 moles
0.85 kg MDMA.HCl (229.7 g/mole) = 3.70 moles

3.70/5.61 = 0.66

=> Yield: 66% (Not stellar, but okay, considering the ease)


  • Guest
Cub always gets around 85 grams out of 100...
« Reply #11 on: October 14, 2003, 03:52:00 PM »
Cub always gets around 85 grams out of 100 grams of ketone.Maybe ketone he has been using is bit impure.It was made by who knows who and has been standing at room temperature for at least a year.Or maybe silicagel helps.Will try this silicagel stuff in near future.


  • Guest
This method might be easier and higher ...
« Reply #12 on: October 17, 2003, 12:58:00 AM »
This method might be easier and higher yielding than Al/Hg, but methylamine is not obtained easily. Instead of using MeNH2 (methylamine gas) in this reaction, can one substitute nitromethane as the methylamine source in the same way nitromethane is used in Al/Hg?


  • Guest
« Reply #13 on: October 17, 2003, 01:16:00 AM »
nabh4 doesn't reduce the nitro group..(so you can't do a one pot with nitromethane)

you could always a Al/Hg on nitromethane to make your methylamine first...(pain) but it saves buying it


  • Guest
In this case methylamine was bought but cub...
« Reply #14 on: October 17, 2003, 05:35:00 AM »
In this case methylamine was bought but cub has also used home-made methylamine with same yields.He has been constantly getting 85% w/w out every time(kilo scale and 100 gr scale)Maybe he should silicagel.Or try to use purer ketone.


  • Guest
methylamine via pd/c?
« Reply #15 on: March 24, 2004, 07:45:00 PM »
Has someone tried to make methylamine by reduction of nitromethane with pd/c and ammonium formate? My idea would be to reduce nitromethane with CTH under anhydrous conditions, slowly heat up the rxn mixture and bubble the resulting methylamine gas into aeq. HCl to get the hydrochloride in aequous (stable) solution. By weighing the HCl before and after gassing one could determine the amount obtained. Could this work?


(by the way - I've just become newbee, thanks!  8) )


  • Guest
Nitromethane -> Methylamine
« Reply #16 on: March 24, 2004, 09:37:00 PM »


  • Guest
nitromethane -> methylamine (2nd)
« Reply #17 on: March 25, 2004, 10:33:00 PM »
Seems SWIA should UTFSE a bit more...


looks good too for preparing your own methylamine hcl. Raney nickel could be substituted with pd/c easily (SWIM has no raneyNi :) ). But my question is: how would one separate methylamine? solvent extractions at -7°C? Would't bee easy ;) Any suggestions? washing with cold brine and then boil off the desired amine perhaps?



  • Guest
Whats so difficult about the Al/Hg reaction?
« Reply #18 on: March 27, 2004, 06:53:00 PM »
Whats so difficult about the Al/Hg reaction? The only potential problems/failures are ones caused by the inexperienced persons running it, but that can be the case with any reaction regardless of its seemingly simplistic protocol. A good solid understanding of reaction procedures/details brings that possible failure % down considerably with any reaction. Some bees have shown/proven far better yield %'s via the Al/Hg/nitro in half the time, & Osmiums Al/Hg version brings those yield %'s up even higher yet.


  • Guest
hi SWIM might bee just asking some stupid...
« Reply #19 on: March 27, 2004, 08:43:00 PM »

SWIM might bee just asking some stupid questions....

1) Can SWIM use Methylamine solution in the borohydride reduction method? If yes, can SWIM just add it to the rxn vessel like adding water?

2) If not, can SWIM boil the Methylamine solution to make the gas, as the boiling point is 48°C? It sonds like a bad idea as it has the following hazards "Vapors or gases may ignite at distant ignition sources and flash back.
  Vapor/air mixtures are explosive."

any kind words for the answers would be much appreciated.:)

Edit: 3) And the weight of the Methylamine mentioned in the NaBH4 synthesis is in .hcl or gas?