Author Topic: Alternate procedures for the activation of aluminium in reductive aminations (Read 457 times)

Helgoland · « **on:** February 04, 2011, 08:51:33 PM »

I thought this deserved its own thread.
Some people can't get HgCl₂ or just dislike the thought of messing with it.
Here's the the thread for you-and a great paper to begin with.

H

Oerlikon · « **Reply #1 on:** February 04, 2011, 11:24:12 PM »

Al,Zn,Mg,Cu and few other might do the trick...
But why bother if Al/HgCl2 works so well?!
Mg and buffer they use is harder to obtain than Hg and salts,at least to most of us!

Sedit · « **Reply #2 on:** February 05, 2011, 12:39:51 AM »

Quote from: Oerlikon on February 04, 2011, 11:24:12 PM

Al,Zn,Mg,Cu and few other might do the trick...
But why bother if Al/HgCl2 works so well?!
Mg and buffer they use is harder to obtain than Hg and salts,at least to most of us!

Al won't do the trick hence the need for Hg to activate it, Copper complexes with amines so odds are thats out the window as well. Zn is a possibility but you will see if you bothered to read the paper that it is limited to aromatic amines and to hear that Mg is successful that is great. No, its beyond great.

If you honestly have to as why use Mg over Al/HgCl2 then odds are you should just avoid the reaction all together... both of them since MgCl2 sucks and it sounds like you have no respect for it. Mg is simple to get over the counter and non-toxic. Triethylamine can be had as well and is non toxic. This reactions seems that it would be as simple as adding a ketone to AcOH and Triethylamine and once the correct weight is reached allowing for excess amine, add Magnesium chunks and you can cap it(sort of) and forget it since it says the reaction is done in 24 hours at room temperature

Helgoland thanks for the paper it does indeed warrent further investigation.

Oerlikon · « **Reply #3 on:** February 05, 2011, 01:55:29 AM »

I just gave examples I heard of,thanks on details Sedit!
Cu is used in one reaction in form of salt to activate something else,forgot what...

Biggest issue for home chemist is OTC availability of chemicals.
And this is significant variable over the globe!

Sedit · « **Reply #4 on:** February 05, 2011, 02:36:03 AM »

CuSO₄ + NaCl is used to activate Aluminum as well but there has never been a clear cut yes or no that it would work on reducing various substates. I have used it to reduce the nitro grouping of Nitromethane to Methylamine but there are alot of dissolving metal reductions that will perform the same feat without the ability to reduce an imine which is needed here.

With this reaction however it is much more over the counter then a normal amalgum reduction since Magnesium can be had in the form of fireblocks and anodes for water heaters and Triethylamine can be had from certine wood cleaning and stripping products as well as being produced as a nuisence when adding Bromoethane to (aq)NH₃ in an attempt to make EtNH₃. Since the TEA is not consumed in the reaction a little can go along way as long as isolation is not effected to much.

I honestly feel this is indeed a huge breakthru that im shocked I have never seen discussed before.

Oerlikon · « **Reply #5 on:** February 05, 2011, 03:38:55 AM »

I actually had this document in original form (in Serbian) on old Hard Disk but never
thought it was so fascinating since yields are much lower than Al/Hg...

Silly me!

I am sure there must be more on that subject!
If I found it I will translate for you all.

Maybe roaming trough national chemistry library to find more
on novelty reductive amination methods will do the trick!

Sedit · « **Reply #6 on:** February 05, 2011, 04:32:16 AM »

Present your evidence that the yeilds are lower then Al/Hg... 50-89% yeilds is not low at all. The 50% is for primary amines and is to be expected as the Schiff base formed from them are highly unstable to water and form a resonace structure. Secondary amines do not form the same structure and the imine is stable under moderate wet conditions meaning the yeilds will jump dramaticly for secondary amines as opposed to primary.

Oerlikon, get some Acetone or better MEK and start aminating using Ammonium acetate and Methylamine, record everything about it and compair your results to those listed in the text and see how low these really are.

akcom · « **Reply #7 on:** February 05, 2011, 07:26:58 AM »

Closest substrate they have (P2P + butylamine) was only 79 percent yields. Using shorter chain amines is going to reduce that yield even further. If it weren't for the triethylamine & methylamine this reaction might be decent for a first time chemist not overly concerned with yields, but if you can get either of those you can definitely get HgCl2

Acetone and MEK are really not similar enough to our favorite substrate to draw any reasonable inferences. Never the less, the authors results more than speak for themselves.

As it stands this is a very interesting paper on reductive amination, but when it comes to easy to obtain, high yield, low fuss reactions osmiums al/hg is hard to beat.

overunity33 · « **Reply #8 on:** February 05, 2011, 07:38:15 AM »

Aluminum/Gallium alloy? Reacts much faster apparently.

Sedit · « **Reply #9 on:** February 05, 2011, 02:30:51 PM »

The concerns of yeilds here are confusing me, you stated only 79% yeilds from the simular reaction which I did infact notice myself. 79% is not bad yeilds. To return almost 80% yeilds from an amalgum reduction, esp after there lengthy workup is taken into account.

I would like someone with experience beyond reading Rhodium archives to chime in an back me up here please.

{Edit}

I would like to draw everyones attention to a few of the more common known writeups floating around.

67% yeilds
Methamphetamine via Reductive Amination of Phenyl-2-Propanone

60% yeilds
Reductive Amination of MDP2P with Al/Hg + Nitromethane
by Methyl Man

Hows that 79% yeilds looking???

zzhuchila_clocker · « **Reply #10 on:** February 05, 2011, 06:16:36 PM »

Quote

CuSO4 + NaCl is used to activate Aluminum as well but there has never been a clear cut yes or no that it would work on reducing various substates.

for reducing 2,5-dimethoxynitrostyrene it works.

letters · « **Reply #11 on:** February 05, 2011, 07:51:04 PM »

as some1 suggested, Al/Ga is quite nice. you can buy the gallium in alloy form from ebay for not too much ("liquid metal"). only a little is needed.
you then rub/smear the gallium alloy on the Al, which activates it and then it can be used like the normal al/hg amalgam.
once done the al will be transformed to al oxide (alumina of sort). you can then dissolve it in alkali hydroxide solution to collect the liquid metal back (same as with Hg). The added benefit is OTC and virtually no toxicity

akcom · « **Reply #12 on:** February 06, 2011, 01:09:10 AM »

Quote from: Sedit on February 05, 2011, 02:30:51 PM

The concerns of yeilds here are confusing me, you stated only 79% yeilds from the simular reaction which I did infact notice myself. 79% is not bad yeilds. To return almost 80% yeilds from an amalgum reduction, esp after there lengthy workup is taken into account.

I would like someone with experience beyond reading Rhodium archives to chime in an back me up here please.

Chiming in here: over 90% w/w using osmiums write up and scrap aluminum "sheeting" (approx half a cm thick). Ketone distilled twice under vacuum. One spot on TLC, visualized with DNP

Quote

I would like to draw everyones attention to a few of the more common known writeups floating around.

67% yeilds
Methamphetamine via Reductive Amination of Phenyl-2-Propanone

60% yeilds
Reductive Amination of MDP2P with Al/Hg + Nitromethane
by Methyl Man

Hows that 79% yeilds looking???

You're not comparing apples to apples. First example uses aq MeNH2. Someone with more experience on this substrate can provide more input than I, but from what I remember reading the P2P imine is not as water stable as the MDP2P imine so aqueous yields are lower.

As for MDP2P and nitromethane thats even more obvious. Nitro yields are ALWAYS lower than simple imine reduction. Compare it to MDP2P + MeNH2 (in alcohol) for a more reasonable picture.

I'm not saying this procedure is bad, simply that if you can get (or make) HgCl2, you're better off with an Al/Hg. No triethylamine. One less chemical to worry about. Extremely otc. Making HgCl2 is not fun, but once you've got a couple grams, you're good.

psychexplorer · « **Reply #13 on:** February 06, 2011, 01:48:32 AM »

Quote from: Oerlikon on February 04, 2011, 11:24:12 PM

Al,Zn,Mg,Cu and few other might do the trick...
But why bother if Al/HgCl2 works so well?!
Mg and buffer they use is harder to obtain than Hg and salts,at least to most of us!

Because HgCl2 is on the DEA special surveillance list and should never be ordered by a clandestine chemist. (although Hg substitutes exist)

Because less toxic reagents should be used if they get the job done.

Because mercury disposal is either a pain in the ass, suspicious, or bad for the environment (down the drain).

I've always wondered about gallium ever since I first saw the Hg/Al catalyzed reductive amination. Since the Hg is used for nothing more than activation of the Al, would Ga work just as well? For the reaction in question the Ga will stay in its liquid phase.

Anyone have any good refs for the Ga? It'd be great to eliminate a toxic and watched substance from our procedure.

Yes, I know working with Hg isn't a big deal for a competent chemist as far as lab safety is concerned. Personally, I'd rather see the stuff stay unmined in the original ore body if there is a way to replace it. Not contributing to global demand for Hg is a fringe benefit.

If Ga works just as well (as someone has suggested) then the Hg route should be considered dead.

I'm not currently in a position to test this myself, although I will in time if nobody else already has.

Edit: This question has come up a couple times on SM and the replies were all theory with respect to RA on certain popular ketones.

Wizard X · « **Reply #14 on:** February 07, 2011, 10:15:47 AM »

In 2007, it was discovered that an alloy of aluminium and gallium in pellet form added to water could be used to generate hydrogen. The process also creates alumina, but the expensive gallium, which prevents the formation of an oxide skin on the pellets, can be re-used. This has important potential implications for a hydrogen economy, as hydrogen can be produced on-site and does not need to be transported.

http://en.wikipedia.org/wiki/Hydrogen#Production

Oerlikon · « **Reply #15 on:** February 07, 2011, 10:51:09 PM »

As I said,same chemicals that are piss easy to get OTC in one country are unobtainable in other!
When I get all the chemicals needed to run Jon's halogensafrole method few times I won't even consider
Al/Hg red. amin. or anything similar any more!

If HgCl2 works for activating Al than why didn't anybody considered using Ga salts (Ga nitrate for instance)
for the same purpose instead of screwing with elementary Ga?!

Hg was bitch to find,but I have more Hg now than I can spend in 3 lives and so much HgCl2
that it will become obsolete when once when new method is perfected.

When using Al/Hg+nitromethane my yields vary greatly form synthesis to synthesis.
Sorry,I don't keep books for obvious reasons but yields were from 20-80%.
I have feeling that I screw-up most times on extraction and titrating.

Never even tried to use methylamine since it can't be found here no mather what I try. (I know I can make it, but I was lazy)

letters · « **Reply #16 on:** February 13, 2011, 10:28:14 PM »

Oerlikon, the liquid Ga is easy to get worldwide. just go to fleabay and type in liquid metal. Have not tested it for reductions, but does work nicely for hydrogen generation.

Enkidu · « **Reply #17 on:** May 10, 2011, 02:02:58 PM »

There's a thread on the hyperlab about the CuSO4 method. It's called

?? ??

?? ,

?? ?

? started by bu6men.

sassa · « **Reply #18 on:** May 10, 2011, 11:20:28 PM »

Hi again Oerlikon!

.I can´t believe you have patience enough to run all the process involved from the start,and not have 5-6 hours for letting boiling a mix af paraformaldehide,ammonium chloride and water

.Making methylamine to me was the most easy procedure of all the synthesis without doubt,in fact,the first time i used my distillation set-up was to make that methylamine,and i didn´t almost know how to make water boil!Really with your knowlegement at this moment ,of course if you have acces to chemicals,you can make it enough on an afternoom to make all aminations you will need on future if you scale up.I have seen on ebay so many times formaldehyde 40% and ammonium chloride for sale....
I have to said too,Osmium´s method/amounts yields to me like 90%,only few grams less than ketone used.So for making mdma,at this moment,i think struggling with nitrometane it´s only for people can´t make/buy methylamine or have no acces to chemicals involved on its synthesis.Have to say too,25 gr. HgCl2 it´s plenty for years of chemistry on small batches.
Another thing will be the ethical use of Hg and if all of us deposite it on a secure way....

jon · « **Reply #19 on:** May 10, 2011, 11:34:10 PM »

the original process activates the aluminum with naoh to remove the oxides.
then this is washed, and the aluminum amalgamated and washed with ethanol/ether.

Author Topic: Alternate procedures for the activation of aluminium in reductive aminations (Read 457 times)

Helgoland

Alternate procedures for the activation of aluminium in reductive aminations

Oerlikon

Re: Alternate procedures for the activation of aluminium in reductive aminations

Sedit

Re: Alternate procedures for the activation of aluminium in reductive aminations

Oerlikon

Re: Alternate procedures for the activation of aluminium in reductive aminations

Sedit

Re: Alternate procedures for the activation of aluminium in reductive aminations

Oerlikon

Re: Alternate procedures for the activation of aluminium in reductive aminations

Sedit

Re: Alternate procedures for the activation of aluminium in reductive aminations

akcom

Re: Alternate procedures for the activation of aluminium in reductive aminations

overunity33

Re: Alternate procedures for the activation of aluminium in reductive aminations

Sedit

Re: Alternate procedures for the activation of aluminium in reductive aminations

zzhuchila_clocker

Re: Alternate procedures for the activation of aluminium in reductive aminations

letters

Re: Alternate procedures for the activation of aluminium in reductive aminations

akcom

Re: Alternate procedures for the activation of aluminium in reductive aminations

psychexplorer

Re: Alternate procedures for the activation of aluminium in reductive aminations

Wizard X

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Oerlikon

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letters

Re: Alternate procedures for the activation of aluminium in reductive aminations

Enkidu

Re: Alternate procedures for the activation of aluminium in reductive aminations

sassa

Re: Alternate procedures for the activation of aluminium in reductive aminations

jon

Re: Alternate procedures for the activation of aluminium in reductive aminations