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alking
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Al/Cu reduction not working as expected
Previously I have used the common Al/Hg method successfully, it's a pretty straight forward process. I'd like to find a less toxic alternative however
and that is when I discovered Al/Cu as brought to my attention by another poster here. My first couple attempts have failed however and I'm at a loss as to why. So far this has only been tried on beta-nitrostyrene as it's
cheap, mentioned as successful in that thread, and I did not see reason to try anything else if I'm getting failure here.
The rxn runs as expected, following TheCopperMan's procedure to the T, until I go to distill off the alcohol post reaction. For some reason during
this I get a lot of red coloration forming (previously nearly clear/white post reduction), deep blood red, and after the alcohol is removed this
floats on top as it is not water soluble. I have to assume this is, or rather was, my product. There is some mention of this in the thread, but not
much is said about it.
My initial thought is that this is probably a copper complex forming, and with Al/Hg I normally basify and separate the alcohol layer before
distilling it out so I too thought that may have something to do with it (though I don't see why). So I tried again exactly as I would do with Al/Hg.
So post rxn I drop it to RT, basify, separate the alcohol layer, and then filter off any metals that may still be floating about. From here I dilute
with dH20, and neutralize it so as to not steam distill any freebase product as I'm stripping the alcohol and to protect it from any possible side
reactions from any excess base. Again however I get a deep red coloration over the course of the distillation, and at this point there should be no
copper left to form any complexes (right?) so I can rule that out.
This just leaves me kind of at a loss as to what is going on though. My best guess at this point is maybe the imine is formed but for some reason will
not go to the amine and instead something causes it to polymerize, but I really don't understand why that would happen. The nitrostyrene is certainly
reduced as noted by the solution going from yellow -> clear. If it can form an imine then it should be able to form an amine through the same
process though I would think. Before wasting anymore time and materials I thought it best to look for some kind of insights. There are a lot of
people reporting failure in that thread, but quite a few do have success and someone even reported, iirc, a 75% yield of PEA when reducing
beta-nitrostyrene. I do believe that same person had a 0% or close to it yield in other attempts with no explanation why or what changed, but I'm
convinced this must be a viable alternative and that I am just doing something incorrectly.
I guess I should mention too that the one deviation from copperman's writeup is that I am using a magnetic stirrer and since copper is magnetic that
may pose a problem, however it's clearly being reduced to something and all or most of the aluminium dissolves as expected so I can't see that being a
factor.
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Nicodem
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Melgar
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Copper isn't magnetic... at least not ferromagnetic.
If something is behaving like an imine but is much more stable, that's a good sign you're dealing with an oxime, which is perhaps the most common
intermediate that reduction methods get stuck on when reducing nitroalkenes.
If you're in the US, I could send you galinstan via ground shipping, for $0.50 / g +$10 shipping, btw. It's a nice alternative to Hg for Al
reductions, although I've only confirmed that it will reduce nitroalkanes to amines experimentally, nitroalkenes should work, but I'd need standards
to test against to make sure I'm getting the desired amine in the products.
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clearly_not_atara
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If a complex did form it could certainly be soluble in alcohol or other organic solvents. I know little about Al/Cu but what I do know about
dissolving aluminum reductions is that they usually have to be vigorous or the reduction won't be complete. The oxime is a common byproduct. I don't
know what you have to do exactly but the aluminum should be dissolving rapidly.
I think it's basically a galvanic process, so why not just use some alligator clips and wire and a piece of copper to serve as a cathode? :p
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Alice
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First of all, that's a very puzzling observation, alking.
So it turns red suddenly or constantly due to removal of the alcohol? Can you reverse the effect by adding alcohol again, adding HCl or NaOH? What was
the pH of the mixture you've evaporated? What was the pH after removal of alcohol? Are you able to dissolve red precipitate in any sort of organic
solvent? You may try to recrystallize red precipitate in order to find evidence for not having a polymer because polymers are hard to crystallize. You
may exclude the presence of copper in red precipitate by the Beilstein test (adding a halogen salt like magnesium chloride).
As others have mentioned, this may be partially reduced nitro styrene, a polymer thereof as well as an oligomer, like a cyclic timer. Find evidence
for partial reduction by using the double amount of Al. An oxime or an imine as monomer wouldn't be deep red normally unless it is a copper complex or
a tautomer. The tautomer of the oxime is the hydroxylamino stryrene and the tautomer of the imine is the amino styrene, thus fully conjugated. No idea
if this would be deep red. Of course these styrenes may also polymerize. But I'm just guessing.
[Edited on 17-4-2017 by Alice]
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alking
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It could be an oxime, though I'm not sure how to confirm that, and I still cannot figure out what might be hindering it from proceeding. To give a
little more details on the process it seems that after separating the alcohol, neutralizing it, diluting it with H2O, and then distilling it off, it
seems that when it hit around 60C the color change started to occur. First it's a light pink and as the distillation goes on this turns into a dark
blood red. After the alcohol is removed there will be some pink in solution, a lot of dark red floating on top, and some crystals that are at the
bottom which are also pink. I suspect these crystals are just aluminum salts that have absorbed some of the polymer, but I am not sure, I did not test
them. When neutralizing the solution prior to distillation it goes from clear colorless, maybe the slightest tint of yellow (barely any color at all
though), to a foggy white as something precipitates out. I assumed this was some aluminum hydroxide or maybe aluminum chloride coming out of solution
and so I did not bother to filter it off. This happens with the Hg too and never posed an issue.
Also the 2nd time I did this experiment I refluxed it longer in case it didn't go to completion, maybe 2x as long, and still no polymer formed, so
there's something about either the removal of the reducing agent or the removal of the alcohol that encourages the polymerization to occur. However as
noted in the first test when distilling the alcohol directly out it still occurs which makes me think it has more to do with removal of the alcohol,
which kind of confuses me too, there's a good amount of H2O and alcohol so it's not as if the alcohol would do much to prevent a rxn with the H2O if
that's what's occurring.
The 2nd time I refluxed it longer because there was still a good bit of aluminum left, but I had the same amount left as before, and I tend to always
have a similar amount left using mercury too.
Quote: Originally posted by clearly_not_atara  | If a complex did form it could certainly be soluble in alcohol or other organic solvents. I know little about Al/Cu but what I do know about
dissolving aluminum reductions is that they usually have to be vigorous or the reduction won't be complete. The oxime is a common byproduct. I don't
know what you have to do exactly but the aluminum should be dissolving rapidly.
I think it's basically a galvanic process, so why not just use some alligator clips and wire and a piece of copper to serve as a cathode? :p
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I did not mention it, but the 2nd time I used an addition funnel to slowly add the styrene as well specifically to not create a vigorous reaction. I
do not think this mattered though as both times the results were the same, and that's how I do the mercury reductions too, I don't even let them get
to a reflux temperature and I have not had issues. In fact I even have better results as if I add it all at once I get some polymer formation with
mercury, though not much, yet when I add it slow and keep it below 70C after the rxn is complete my solution is completely colorless (the polymer
formation happens during the rxn in this case, not afterward). Why does the speed of the reaction matter? I can't see any reason it would, or would be
halted. There's no side rxns you're trying to out compete and so long as you have active aluminum you should be reducing/generating hydrogen
regardless of the rate. Am I missing something involved there?
| Quote: Originally posted by Alice | First of all, that's a very puzzling observation, alking.
So it turns red suddenly or constantly due to removal of the alcohol? Can you reverse the effect by adding alcohol again, adding HCl or NaOH? What was
the pH of the mixture you've evaporated? What was the pH after removal of alcohol? Are you able to dissolve red precipitate in any sort of organic
solvent? You may try to recrystallize red precipitate in order to find evidence for not having a polymer because polymers are hard to crystallize. You
may exclude the presence of copper in red precipitate by the Beilstein test (adding a halogen salt like magnesium chloride).
As others have mentioned, this may be partially reduced nitro styrene, a polymer thereof as well as an oligomer, like a cyclic timer. Find evidence
for partial reduction by using the double amount of Al. An oxime or an imine as monomer wouldn't be deep red normally unless it is a copper complex or
a tautomer. The tautomer of the oxime is the hydroxylamino stryrene and the tautomer of the imine is the amino styrene, thus fully conjugated. No idea
if this would be deep red. Of course these styrenes may also polymerize. But I'm just guessing.
[Edited on 17-4-2017 by Alice] |
It turns red constantly, it's a slow transition over maybe 30 minutes from the point it hits about 60C. It turns light pink and then by the time maybe
half the alcohol is removed it seems to be completely polymerized, or at least there's no further color change noted. The PH I measured before
distilling was 6.9, but I did not calibrate my meter so it could be off. If anything it would have been slightly acidic though and within .3 or less
as I calibrated it later that day (or maybe the next?) and it measured a 7.0 calibration solution as 7.1. I did not test the PH afterward. The red
stuff is readily soluble in organic solvents. Basifying it does not change the color, nor does acidifying it, and it does not form salts as acidifying
it does not make it water soluble. I'm quite certain it's a polymer formation, I'm just not sure from what, why, and more so why it only happens at
the point in which it does (as opposed to during the reduction itself), the last one is really what puzzles me. I assume an intermediate imine of
course as they're prone to polymerizing and due to the lack of yellow color I have to assume the styrene was fully reduced. I always have excess
aluminum left so it's not due to running out of reducing agent.
I have largely dismissed a complex due to the fact that ALL of the product seems to form this red color and there's not enough copper present to
complex all of it, unless I'm misunderstanding how that works anyway. After filtering it and then washing my funnel with HCl to remove the aluminium
I'm left with small bits of copper on the filter too, so if it is forming a complex it's not occuring with all of the copper. Of course this copper
could be inactive too, it is kind of brown as opposed to shiny, not sure why as copper oxides are not brown.
I am correct in that a complex is similar to a salt, so you'd need an equimolar amount (or some fraction there of anyway) of metal:amine right? Since
I am using ~300mg of copper and 3g of styrene most of my product should still be left uncomplexed if that is what's going on. Maybe the complex forms
and prevents further activation of the aluminum, thus halting the reaction? That is a possibility I have not thought of.
[Edited on 22-4-2017 by alking]
[Edited on 22-4-2017 by alking]
[Edited on 22-4-2017 by alking]
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clearly_not_atara
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There are at least two side reactions. The first is the rearrangement of nitrosoalkene intermediate to oxime. The reduction proceeds:
Nitroalkene -> nitroalkane -> nitrosoalkane -> hydroxylamine -> amine
The other side reaction occurs when the nitroalkane reacts with the nitroalkene in a Michael addition. This occurs because nitroalkenes are Michael
acceptors and nitroalkanes are Michael donors. This reaction is promoted by base and suppressed by acid.
The other other side reaction is the hydrolysis of oxime intermediate to ketone; this only occurs if the rxn mixture is far too acidic. It should
never be a problem and you'll notice way too much H2 and heat if it does happen.
Reduction of the Michael rxn dimer produces a 1,3-diamine that may complex with copper or the corresponding 1,3-dioxime. This might be a good ligand
for copper. Copper can bind to two bidentate ligants in one complex as is seen with e.g. Fehling's reagent.
However you don't care about any of the theoretical nonsense you want the rxn to work and I agree. I think the pH should be about 5 or so. This ought
to suppress the Michael reaction.
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Alice
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Sometimes a solution looks almost colorless despite having some colored compounds in it which becomes only visible by evaporation. Therefor I've asked
for reversibility. From your answers I suspect this is not the case here.
The Cu⁺ tetramine complex is soluble colorless and is oxidized by air giving Cu²⁺ tetramine. This way copper might be invisibly present in the
solution.
For comparison, the copper glyoxime complex is red and maybe other oxime complexes are red too. Cu²⁺ usually has four ligands (e.g. the tetramine
complex) plus two water molecules. A hypothetical complex may consist of a Cu²⁺ ion and four ligands or a polymer-like aggregate of the same ratio.
| Quote: | | I am correct in that a complex is similar to a salt, so you'd need an equimolar amount (or some fraction there of anyway) of metal:amine right? Since
I am using ~300mg of copper and 3g of styrene most of my product should still be left uncomplexed if that is what's going on. Maybe the complex forms
and prevents further activation of the aluminum, thus halting the reaction? That is a possibility I have not thought of. |
3 g styrene is 20 mmol and 0.3 g copper is 4.7 mmol. About 4:1. But as some styrene is reduced fully, some partially, some styrene is lost due to
polymerization or other side reactions, and some copper is reduced to metal and removed by filtration, we're dealing with an unknown ratio which might
or might not suit this hypothesis. What's the weight of the red residue after removal of solvent?
All of this is just meant as a vague possibility until there is at least a qualitative test for copper.
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lordofthechemicals
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I have tried this method 2 times with p2np with no result. product smells like amine but isnt stable becomes dark red after 4 5 hours and isnt soluble
anymore in petr ether. Copper isnt soluble in ether so i think complexes should be excluded. There is some kind of polymerization going on i suppose?
i use sulfuric in ethanol 10% as sulfate isnt soluble in ethanol and if evrything is ok should fall off in white flakes. Maybe its really the pH that
should around 5 during the reaction?
[Edited on 26-4-2017 by lordofthechemicals]
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Alice
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| Quote: | | Copper isnt soluble in ether |
What do you mean by "copper"? I assume a copper salt? Or the metal?
A complex isn't really the same as just a salt. Just think about all those transition metal complexes and the various reactions run in organic
solvents, called homogeneous catalysis. Petrol ether is a highly nonpolar solvent. Many organic compounds are insoluble in petrol ether.
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clearly_not_atara
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| Quote: | Hello, I have been watching this thread with great interest.
In reply temple, I reduced 2,5-dimethoxynitrostyrene to 2C-H in good yield. The styrenewas also of terrible quality. 4g was reduced to around 3ml.
Cu sulphate and salt were added originally, then another few grams of Al and cu chloride added when it died down.
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Not exactly on topic but it's a trick of the trade that terminal nitrostyrenes can be reduced effectively with zinc powder and HCl (Leminger
reduction), whereas internal nitroalkenes such as phenyl-2-nitropropene require more advanced approaches.
Perhaps when analyzing the results of this reduction it would benefit our investigation to note whether a terminal or internal nitroalkene is being
reduced. It is possible that terminal nitroalkenes are reduced more easily by Al/Cu as well, which could account for inconsistent results with this
method.
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tsathoggua1
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I attempted to reduce propan-2-one last night using Al (as foil), HCOOH (54%) and CuCl2 (before finding out it doesn't work worth shit on small liear
aliphatic ketones), not out of any great desire for the end product, just on a test tube scale, since I was sleepless and wanted something to do.
First a nugget of rolled up Al foil was added to the tube, followed by acetone, then the formic acid. There was no reaction of any kind until addition
of CuCl2 (an initial 2 drops of saturated solution to get the rxn started, then a further 6 drops to a test tube filled with 50-50 acetone/HCOOH upon
which vigorous hydrogen evolution began, along with deposition of a fine sludge of dark ruddy color, later produced via addition of CuCl2 to Al, and
isolated, forming a fine black powder when heated in the hottest portion of a propane torch flame, the powder appears to be copper metal in finely
divided form.
Rate of attack seems strongly dependent upon concentration of the CuCl2, for the initiation of the rxn succeeded (with substrate ketone and acid) with
just two drops taken from a bowl of almost fully crystallized solution of the chloride, but began to bubble violently when the remaining drops were
added.
Also, whilst the H2 evolution continued with CuCl2/Al/H2O alone for a considerable duration (I ended up going to bed eventually, and, having taken my
antiseizure medication (chlormethiazole, fairly strong sedative) and as I was tired but sleepless, some 15mg nitrazepam, and opioid pain medication
(I'd get no sleep at all otherwise, with my screwed up joints and nerve damage) did not again wake until almost 6:30 or so the next evening by which
time any CuCl2 ought to have been reduced to copper (0), and there indeed was a sizeable quantity of copper, with respect to the amount of CuCl2 used,
however evolution of H2 whilst slowed after many hours, carried on, and although almost so, it STILL has not ceased 100%, its still giving off a slow
stream of hydrogen bubbles now. Another lot, upon deliberate addition of a tetrammoniumcopper (II) complex (the chloride, so as not to complicate
things anymore than needs be with other anions) it instantly discharged the deep blue of the copper complex, prepared from aqueous NH3 and CuCl2 (aq)
and seemed to cause significant foaming and turned much of the remaining Al to sludge of a fine consistency and grey color, like one would expect from
an Al/Hg amalgam reduction post completion and workup and dramatically slowed the hydrogen evolution down. Its still going however.
I wonder if its acting (with just CuCl2 and HCOOH/Al or CuCl2/Al/H2O) as an electrolytic couple like zinc-copper, nickel-copper couples, since the
reaction seemed to accelerate after some initial deposition of copper once all CuCl2 to be added had been so, and decomposed water/acid via catalytic
or galvanic means), with an initial acceleration followed by a slowing as the CuCl2 appeared to be largely consumed, then subsequent pickup of rate of
evolution of H2 after some Cu deposition.
Will try using the Al/Cu system to attempt reduction of an aliphatic nitroalkane (nitroethane, since the ethylamine could easily be detected, and
trapped in alcohol solution, to be driven off by a little brief heating when ready to assay the results, aiming for a qualitative assay at first,
since I have no current need for ethylamine, I've got plenty nitroethane, I'd try reduction of a beta-nitrostyrene, but unfortunately currently have
no nitromethane, only nitroethane, annd given the formation of a coordinating lewis acid/presence of same to begin with I'd expect the reactivity of
the nitro group to be increased and to obtain if anything useful, 1-phenyl-propan-2-one rather than amphetamine, or possibly in-situ formation of some
N-ethylamphetamine via reduction of nitroethane to ethylamine and reductive amination of P2P in-situ with unreacted ethylamine.
I'm not hugely enthusiastic about trying this for P2P synthesis, since Fe/HCl/FeCl3 can already do this. And given the substrate being tested is a
nitropropene rather than nitrostyrene, the Fe/HCl/FeCl3 system won't reduce nitropropenes to the amine, unlike beta-nitrostyrenes.
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lordofthechemicals
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can someone give detailed literature references about pH ,temperature and reagent concentrations needed for successful reduction of p2np to amine ?
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woelen
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@lordofthechemicals : What are you up to? If it smells like cookery, then it most likely is cookery. We do not allow spoonfeeding requests for the
synthesis of drugs or drugs-precursors!
[Edited on 28-4-17 by woelen]
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alking
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This does smell like cookery, but regardless there's plenty of references out there as is of known methods, if you knew what you were doing
you could easily find them with a google search. This thread is about experimenting with a new method though so whether you're trying to make
something illegal or not this post isn't particularly relevant to the topic at hand.
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Corrosive Joeseph
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1 - Charge a round bottom flask with 100 grams of P2NP
2 - Read until your eyes catch fire
3 - Think about it all til your brain explodes
4 - Refux all that for a couple of months
Yields are about 50% with this method
/CJ
Thank me later, there is no fee for this......................
[EDIT] - Sorry, couldn't help myself.................. 
[Edited on 29-4-2017 by Corrosive Joeseph]
Being well adjusted to a sick society is no measure of one's mental health
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lordofthechemicals
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am not at anything if wanted to make phenethylamine would choose al/hg,al/ga, lialh4 or others syntheses with higher yields not al/cu. I use p2np
because of its internal double bond and aliphatic nitro group eg harder reduction than styrene reduction lets say. whats interesting to me is the
mechanism of al/cu reduction and why use copper instead of other transition metal... , to compare this methods yield with others for p2np and also
have lots of benzaldehyde and nitroethane at hand. if this method is useful for this it would be useful for a lot of other compounds. I really dont
understand this moral policing and flaming done everywhere lets complain about alchohol which is more dangerous than nearly every other "ILLEGAL"
compound.
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Alice
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Lordofthechemicals, your opinion about what should be legal and illegal doesn't matter if you're getting charged for the manufacture of a
controlled/scheduled substance. It is not sufficient having just science in mind. Even if you're working at a university or in the industry there is
(depending where you live) a well defined procedure to adhere before being allowed to work with controlled/scheduled substances. This usually involves
communication with the relevant authorities before doing anything practical and a gapless and transparent record of what you were doing.
On the other hand, depending where you live, and because you stated your product may be amphetamine it may be even illegal to give you any advice
enabling you to achieve that goal. Therefor the reactions you received have nothing to do with being square or not. It has something to do with people
not being keen on becoming part of your vortex of self-destruction. 
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Corrosive Joeseph
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@ alking - Any update on this....................? Are you still using magnetic stirring...............?
Copper isn't magnetic but it interacts with magnets in strange ways - check the video in the first link
http://terpconnect.umd.edu/~wbreslyn/chemistry/is-copper-mag...
https://www.quora.com/Is-copper-magnetic
"To be technically precise, pure copper is diamagnetic, meaning that it has no unpaired electrons and will interact with magnetic fields only very
weakly."
The red coloration is puzzling.
I didn't post until now but from what I have I read of this thread before I really wouldn't have much faith.
Seems very hard to get consistent results. I would love to see it work.
beta-nitrostyrene SHOULD be even easier to reduce than P2NP from what I have read.............
/CJ
Being well adjusted to a sick society is no measure of one's mental health
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tsathoggua1
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Just a warning-with Al/Hg reduction, DON'T try doing 100g at a time, start with a tenth of that. That will take up a 1 liter flask nearly to the brim
once the end dissolution of the surplus, unreacted Al foil (don't try using powder, foil crumpled into balls still generates a LOT of heat) is
complete. Both the initial amalgamation is highly exothermic, so have yourself an ice bath handy, temperature should be between 60-70 'C, although
allowances for a brief exotherm can be made with plain P2NP.
Up to 40 degrees 'C whilst amalgamation is being prepared for, then take the heat OFF, and get ready to shift from maintaining at 40 to rapid
changeover to ice bath or it will take off like a rocket. Additional portions of GAA may help once it begins to peter out a bit, as will loading the
Al in several portions. Three, four portions for a 10g reduction should do it, with the addition, with stirring of a little bit more mercuric salt
(make sure its Hg (II), the chloride works just fine, IMO since a nitro group is being reduced mercuric nitrate may decrease the yield a little, tried
with Hg (II) sulfate, this is not a great approach and despite addition in two portions, rxn needed another crack, using HgCl2 because the sulfate is
not terribly stable, although corrosive sublimate can be prepared from it and this salt sublimed (carefully, you really, really do not want to breathe
this in, ingest it, or get it on your skin, it could mean the end of you.
As for Hg quantities, have heard plenty things, from 1g/10g nitroalkene to a little off the tip of a knife. The latter works, 1g/10g seems excessive
really. And can always add a little more in portions with each portion of Al, plus a little extra GAA.
Sometimes GAA alone will restart the reaction.
Apparently Fe/HCl or Zn/HCl works well enough on nitrostyrenes, with nitropropenes however it gives the corresponding P2P (although an in-situ
reduction of nitromethane with the same technique can give the secondary amines, otherwise this reduction using P2NPs gives the primary amine. Ideal
if its simple amphetamine being produced, 5HT2a agonists of the phenethylamine/amphetamine type seem to require a primary amine, with secondary amines
losing much activity, such as ARIADNE, etc.and according to Shulgin, being of antidepressant type effects primarily. Although I've never personally
tasted the 'classic ladies'.
I'd be interested on hearing of results if you have success, or failure, with Al/Cu to reduce nitropropenes, and whether they have primarily
electron-withdrawing or donating ring substitutions, as well as P2NP itself. If your already going to do it, then I'd like to know the results.
Oh and for Al/Hg, do use a long condenser setup, 10g backed up an ice-salt-water-alcohol-ethylene glycol-cooled allihn condenser into the vigreaux
mounted on top, although it didn't get to the liebig above that, got about 1/3 of the way up into the vigreaux briefly, and heavy refluxing before it
calmed down a bit.
Any alternative to Hg is a good thing though if it works with nitropropenes.
[Edited on 30-4-2017 by tsathoggua1]
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alking
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I haven't had time to try any further yet, been busy with other things and haven't had time for any chemistry really, something always seems to come
up. I ordered some gallium as an alternative but haven't had a chance to mess with that yet either. I would like to experiment more with this if only
for the sake of learning though, even if I can't get it to work it would be interesting to at least determine what is happening and why.
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Corrosive Joeseph
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tsathoggua1 - "DON'T try doing 100g"
Apologies for my sarcastic reply.............. Couldn't help myself after reading that post
Anybody who has spent more than 5 minutes reading about this will be well aware of the resulting mercury volcano
Although in fairness, he actually didn't even mention Hg..............
On a contributary note - alking's polymer/dimer/whatever that is, is confusing.............. First thing I would think is eliminate the magnetic
stirring from the re-ax and try again.
And if possible, reproduce CopperMan's and the Gay Doctors work
I'm still not sold on this one..............
Information on reaction of amines and copper(II) ions - http://www.chemguide.co.uk/organicprops/amines/base.html
I remember reading somewhere a 10%NaOH solution cleaves this but I have no reference right now.
I would also recommend attempting reduction with Zinc-Copper salt and/or Zinc-Nickel salt (obviously separately and not together) if someone really
wants to fully explore this (the propene). Like atara says above, Zinc and HCl is well-known for the nitrostyrene.
/CJ
No more spam. I promise..............!!
[Edited on 1-5-2017 by Corrosive Joeseph]
[Edited on 1-5-2017 by Corrosive Joeseph]
[Edited on 1-5-2017 by Corrosive Joeseph]
[Edited on 2-5-2017 by Corrosive Joeseph]
Being well adjusted to a sick society is no measure of one's mental health
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tsathoggua1
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Well yes. Just figured it was highly likely. And in a case involving the potential for 100g worth of 1P2NP, and the corresponding quantity of Hg (II)
soluble salts, better spoon feed some cook type, than have him and whats more, others around them, exposed to a blast of vaporised and sprayed
mercuric salt. 10g in a 1l flask (of P2NP is enough to need a 300mm vigreaux on top of the allihn reflux condenser (also had a 300mm liebig mounted on
top just in case, and the quantity of Al 21-22g (weighed for convenience on a digital scale accurate to 1g for the Al, there was excess leftover after
the fact) and it did indeed get up into the vigreaux, not a huge distance, but nevertheless, the allihn was cooled by an ice/denatured
alcohol/H2O/salt/ethylene glycol bath and it still ended up going a few inches into the vigreaux)
100g P2NP would lead to quite a mess, which cannot be afforded with the likes of HgCl2. That kind of sarcasm could have gotten somebody killed if they
were dumb enough to follow the quantity reccomendation and ignore the rest.
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tsathoggua1
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Oh and Zn/acid is reported to work for nitrostyrenes but not nitropropenes. However, lewis acids can coordinate to the nitro group and result, IIRC in
a P2P. Will have to test something lying around, but tried a Fe/HCl/FeCl2 catalyzed rxn on 2,5-dimethoxy-4-methyl-beta-nitrostyrene once and the
product was liquid, have yet to test for double bond reduction (on the aliphatic chain that is not C=O, bisulfite adduct to test for that, its been a
lower priority than reacquisition of more of the aldehyde)
Can try a P2NP reduction using Cu (II)/Al some time, got plenty nitroethane and benzaldehyde, but currently there are other things that need doing.
And Al/Hg is of course known to work. But some spare P2NP can be knocked out at some point, not in a great hurry though, but it'd be no real loss
trying on some 20-30g
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HollowMan
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Did someone tried the Al/Cu reduction once again successfully with a nitropropene as starting material?
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njl
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Can anyone provide more references for the activation of aluminum with copper ions? This thread had gone on for a surprisingly long time without
citing any directly relevant literature. I do not doubt the efficacy of this system but there are several questions that remain unanswered here.
Personally I am puzzled by the very nature of this reaction.
Is the Cu2+ ion actually relevant, or is it another species produced in situ?
Is the CuCl2 actually catalytic? If so, why does more need to be added in some instances?
Do we know the role the Chloride ion plays here? Is it somehow activating the aluminum by getting through the passive oxide layer?
When a solution of CuCl2 is dripped onto aluminum metal, copper can be seen plating out. If the Cu2+ is reduced to metallic copper, doesn't that imply
that this process isn't catalytic?
Is using CuCl2 in the first place actually equivalent to in situ formation from CuSO4 + NaCl?
Several people have mentioned experimenting with various counterions. Do other halides work?
This article (https://sci-hub.st/https://doi.org/10.1021/ic402674z) claims that their copper catalyst was made by reducing copper salts with NaBH4, and that the
same procedure was used for preparing nickel and cobalt particles. However, the reaction of NaBH4 with Ni2+ does not generate nickel metal
nanoparticles, rather it forms the well characterized nickel boride (same goes for cobalt). Copper boride is (according to my research) a rare species
at best, so the paper is essentially comparing metal nanoparticles to borides as though they were the same.
One of the few linked papers mentions the catalytic activity of Cu nanoparticles. Could it be that the active reduction reaction is the consumption Cu
nanoparticles (as they are oxidized to Cu2+), followed by Cu2+ being reduced back to nanoparticles with the addition of aluminum?
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