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Author: Subject: Experimental: Alternative to Al/Hg - the Al/Cu
pepsimax
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[*] posted on 11-6-2014 at 09:01


I tried this, I wasn't expecting how vigorously it would react! A great deal of my ethanol was boiled away within seconds, my condenser was a crude home built job just to try this as it was dropped a few weeks back. I performed the reaction at half scale, it seemed to go well. Except the solvent loss. I would have expected to receive at least a 50% yeild. Should have left it at that but I added more substrate, more GAA, more ethanol, more Al and ended up with a 10% yield and a lot of polymerised crap.

I have no doubt that this reaction works and can be fine tuned to be one of the greats.

Few Q's, EtOH is expensive here and precious. Would any other alcohols work? Would adding the copper and salt solutions in portions slow it down a little? It's a little hard to keep everything together when it's reacting so hard.

IPA is cheap, as is MeOH. Would I be wasting my time using them? If not would simply distilled meths be ok, mostly ethanol I guess.



[Edited on 11-6-2014 by pepsimax]


Trying with IPA now. Reaction seemed to go ok, slightly less intense on addition of copper though. All the Al chunks have gone after 10 mins, I'll refulx for an hour and see what comes out.

[Edited on 11-6-2014 by pepsimax]

IPA : 0% yeild.

[Edited on 11-6-2014 by pepsimax]
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TheCopperMan
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[*] posted on 12-6-2014 at 18:27


A little update, this reaction was ran again with 10x scale, and this time it was used only 5g CuCl2 and it was heated to 60C initially. And despite using two Allihn condensers, both condensers actually clogged all the way up, that means condensed alcohol was escaping top of condensers and dripping everywhere. Pretty crazy and an extreme fire hazard, and not good for the heart either. Definitely recommend to use some serious high-powered condensers and icewater, this is no joke for sure.

It should be said that initially only 1-2g of the CuCl2 was added. But as nothing much happened and impatience set in, all the 5g of the CuCl2 was just dumped in. Maybe should have waited a bit more. Anyways there seems to be two ways to regulate the initial reaction. 1. regulate the initial temperature. 2. regulate amount of copper solution added.

@ pepsimax
MeOH has been tried and works as well. IPA has not been tried. For regulating reaction, see above points. Oh yes, and denaturated EtOH works well. Should have written that in the original post actually, but yeah, it works just fine.


EDIT:

Another possibility, is to regulate the sizes of the Al-bits. Maybe thicker Al-foil, or crunching it together rather than adding it in flat strips? Just thinking out loud.

[Edited on 13-6-2014 by TheCopperMan]

EDIT 2:
A little appeal. For anyone wanting to attempt this reaction, please do it exactly as per the initial writeup first. Then try any modifications after you get to know it. As already said, if done like that, it should produce more or less the same yield as an Al/Hg. And yes, extractions are a bitch. Many people screw it up. Do it on something that can be steam distilled. Just add NaOH, add water, and boil the water off. Then extract the water, or just add acid directly and boil it off in the open. No mercury worries. No need for pressure cookers. Steam distillation is easy , pure, simple and calming for the nerves instead of messing around with solvens, filtration, gahh...you get a headache just from thinking about it :)

[Edited on 13-6-2014 by TheCopperMan]

[Edited on 13-6-2014 by TheCopperMan]

[Edited on 13-6-2014 by TheCopperMan]
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[*] posted on 12-6-2014 at 20:02


Outstanding! sorry couldn't help myself



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pepsimax
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[*] posted on 14-6-2014 at 04:25


I checked my reaction with IPA and realised I hadn't based it properly - pH 8 (whoops)! Plenty of NaOH has just gone in and I'll update again. The alcohol layer was blood red though so I'm not expecting much.
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pepsimax
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[*] posted on 14-6-2014 at 11:24


Still nothing unfortunately. Could be crappy extraction because I can't steam distill it at the moment due to lack of still head but I doubt it'd be fruitful anyway.
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polsaer
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[*] posted on 14-6-2014 at 13:20


Kinda strange - why it is working with EtOH but not IPA?
Also what is the role of alcohol in this reaction? Al/Hg can be perfectly run without it.
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pepsimax
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[*] posted on 15-6-2014 at 06:26


Could have been dirty substrate, I didn't recrystallise it before use. Impure substrate can lead to a sharp drop in yield in other reactions. The first time I tried it my starting material was very pure, second not so much but would have been fine for general use. I shall up the purity and try again with IPA then report back.
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[*] posted on 15-6-2014 at 06:46


Also i'm getting a lot of black powder in both reactions, copper oxide I presume? Is this normal? Seems to favour hanging around in the organic phase (hexane in my case) making extraction difficult - another reason for steam distillation. Lots of metallic copper particles too.
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TheCopperMan
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[*] posted on 15-6-2014 at 13:19


Yeah, there has sometimes been observed particles hanging around in the interface between organic/inorganic layer after reaction is over. Best tip is to use a minimal amount of CuCl2 to avoid copper creating any problems during extraction. As demonstrated above, 5g was enough for a reaction at 10x scale.

BTW pepsimax, could you post a detailed writeup of how the reaction was ran? Even with the EtOH instead of IPA, 10% is just way too low. When you say 10% yield, this is from the initial amount of substrate added, or the total amount added? (Since you say you added more afterwards)

[Edited on 15-6-2014 by TheCopperMan]
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pepsimax
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[*] posted on 15-6-2014 at 22:33


10% was from the total amount added the first reaction, around 22g. 10g was added to begin with and as it boiled off the alcohol, I added more of everything creating a big mess. As above I think it would have been around 50% if i'd just left it alone. From what I remember.. Half the EtOH, GAA, water and 7.5g thick Al foil folded as you said were added to a 2 neck 1ltr rbf. No overhead stirrer available so a very weighty egg shaped bar was added and set to 1000 rpm, enough turbulence to keep the foil under. 10g substrate was added and heated to excatly 60'c and held there stirring for 5-10 mins. In 2x 50ml flat bottom flasks the copper sulphate and salt solutions were prepared, again to half what you said, salt and water then added through a funnel in the second neck at the same time. Reaction kicked in, within 30 seconds a thick cloud of alcohol shot out the condenser but it looked good. Temp rose to about 93 and i'd lost most my solvent so panicked and added more ethanol and cooling. Everything looked well again so I stupidly added more of everything else hoping to obtain more product but in turn I just ruined what I had. IPA was run the same but without the boilover and extra additions. I'm going to try it with minimal copper chloride instead. Perhaps i'm using way to much sulphate, is it possible it's causing polymerisation like a strong acid could?
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TheCopperMan
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[*] posted on 16-6-2014 at 19:01


Some of the copper sulphate is prepared from H2SO4 and can have a very acidic effect. So best is probably to use CuCl2.

That being said, the reaction was once ran with 50g sulphate and 100g NaCl in an open beaker (as mentioned in original post), and even then yields were on par. So it's dubious that the copper sulphate will affect the reaction negatively.

Nontheless, would recommend to re-run it in denat. EtOH (not sure about IPA, never tried it), use CuCl2 just in case, make sure to avoid solvent escape during the reaction, reflux under stirring for 1 hour and make sure most Al is gone, then add NaOH and preferrably steam distill it out.

[Edited on 17-6-2014 by TheCopperMan]
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pepsimax
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[*] posted on 19-6-2014 at 11:06


Yeah, not in a hurry to try IPA again so waiting on more EtOH, reagent grade. Should be here soon, made a few hundred G's of copper chloride anyway. E- reagent EtOH is taking too long, distilling some purple denat now. Simple distillation is so damned slow! At least i'll end up with some pretty pyridine sulphate crystals to add to the pile.

2.5h later, 287ml... :) Close

[Edited on 20-6-2014 by pepsimax]

[Edited on 20-6-2014 by pepsimax]

Ok, reaction run again. 20g, 300ml EtOH, 45 GAA, 15g thick foil folded as asked. Heated to exactly 60'c, 10g copper (ii) chloride and 20g table salt introduced through second neck.

A fantastic fireworks display ensued. T+10 seconds, Al strips are rapidly and very visibly 'rusting', huge deposits of copper are plating them - very exciting!

T + 15 seconds, everything is bubbling up rapidly. Uh oh, cooling needed.

T + 30 seconds, half the contents of the flask have shot out of the condenser and hit the ceiling over 4 foot above. The flask and condenser are shoved in a bucket of ice water and left to cool. The ice is quickly melted as the reaction stays above 75 but thankfully in the flask.

Over the next 10 mins as much of the mixture as possible is collected with a syringe and replaced in the main flask. A lot is lost. The stuff collected is oily and grey, seems to be multiple phases. It is not known whether this laborious task will be of any use to the total yeild collected which again isn't looking so good.

So from this I've learnt - copper chloride reacts much quicker and violently in EtOH than sulphate. My flask was probably too small. I used the 1 ltr RBF again, next size I have is 5ltr unfortunately. Should have run half scale again.

Either much less copper chloride should be used or less heating to begin with and shoved in the ice bath right before the addition.

Refluxing now, I'll boil off the alcohol then steam distil. I'll report back as always whether I get anything or not!

Good luck anyone who's going to try!

[Edited on 20-6-2014 by pepsimax]
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[*] posted on 20-6-2014 at 07:02


All the Al has gone. It should be noted this particularly violent reaction could have been because of something in the quickly distilled purple methylated spirits, though unlikely. My first boilover was with reagent grade ethanol.

[Edited on 20-6-2014 by pepsimax]next attempt will be thick foil rolled into fairly tight balls and submerged in ice water immediately.

[Edited on 20-6-2014 by pepsimax]
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[*] posted on 20-6-2014 at 11:01


↑
this is pure amateurishness. Why not to try this experiment with 1/5 or 1/10 amoutnt of reagents ?




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pepsimax
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[*] posted on 20-6-2014 at 11:36


Well, first things first I am an amateur. I'm posting excatly what I did in the hope others will not make the same mistakes and hopefully get some advice myself! Secondly i'm sticking to copper mans original procedure as close as possible as he asked. Isn't it the point to report results good or bad? I will scale down greatly the next few tries as it doesn't seem as simple as one imagined.
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[*] posted on 20-6-2014 at 18:00


10g copper chloride and 20g table salt? Damn. That is a lot! Notice in the two posts that was made about using CuCl2, a very small amount was used only and still created a very vigorous reaction. As mentioned above, a 10x scale reaction was ran with only 5g CuCl2 and a nervous breakdown ensued. Would DEFINITELY not substitute 1:1 CuSO4 for CuCl2. The amounts of CuCl2 need to be much less. Sorry, should have written this more clearly.

Primarily there needs to be used less copper chloride, for 20g reaction only 1-2g should do. OR you could probably use the same amount you did, but then definitely the initial temperature needs to be lower, however not sure how low exactly. Or use thicker Al grit, again however, this has not be tried so can't really be helpful with how exactly this needs to be ran. But please, if you do it would be extremely interesting to see the results and a possible writeup! Currently have not access to Al grit so can't run it.

Oh yeah regarding the alcohol. The denat. alcohol used here at least contains MEK or something that is reduced to isobutanol. However it did never interfere with reaction.

[Edited on 21-6-2014 by TheCopperMan]
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pepsimax
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[*] posted on 21-6-2014 at 01:35


Ah my mistake, should have read that better. Finished the steam distil. I took the first 70mls off, there was a strange oil that sunk to the bottom. It appears to be chloroform by the vapours I accidentaly caught and there was a lot of product dissolved in it. The rest of the exected product remained floating on top of the water in the second jar with a few gloops of the presumed chloroform at the bottom. Not sure how any chloroform got in there, is it a common denaturant? When I boiled off the alcohol everything came off at 82 instead of 78 so there was some strange azeotrope, I left it running until nothing would come over at all. I'm quite confused by this "chloroform" or whatever it may be, I don't think i'll use anything other than reagent ethanol next time.
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[*] posted on 21-6-2014 at 02:06


Chloroform? Hmm, that's weird. What exactly is the substrate you are reducing?

If you have access to it, pls check the MSDS for your denaturated alcohol and you could post the ingredient list here so we could see if there's anything that might disturb the reaction. But honestly don't see what that should be. Has tried numerous different denaturated EtOHs and they have all worked successfully.

Also possibility, the quick reaction rate caused some kind of decomposition. Although again, very unlikely unless the substrate you're using is super-sensitive.

Main tip though, re-run reaction w/ less CuCl2, maybe even lower initial temperature. From the experiences with CuCl2 as have been posted, would recommend start temperature of maybe 40 or 50C instead. For the CuSO4 can probably still use 60C.

[Edited on 21-6-2014 by TheCopperMan]
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[*] posted on 21-6-2014 at 03:13


beta nitrostyrene to PEA. Here's the ingredient lest on the alcohol.


3. COMPOSITION/INFORMATION ON INGREDIENTS

INGREDIENT NAME CAS No CONTENT RISK PHRASE CLASS

Ethanol 64 – 17 – 5 90-93% R11 F
Methanol 67 – 56 – 1 5-10% R11, 23/24/25, 39/23/24/25 F,T
Pyridine 110 – 86 – 1 <1% R11, 20/21/22 F, Xn


I simply distilled it with a few drops of H2SO4 in there to turn the pyridine into a salt.

This chloro solvent must have been formed in situ, I can't see anywhere else where it would come from. Everything reeks of chlorine, the water, flasks etc. Some amine has definitely formed though, in what looks like an ok yeild. Due to potential toxicity of this unknown addition, I'm not going to try and refine it though to get a weight. It worked though definitely.

[Edited on 21-6-2014 by pepsimax]
On second thoughts perhaps it didn't work as intended if chloroform was formed, I might have produced a chlorinated version of PEA, who knows? Wish I had access to proper analysis equipment (and the the knowledge to use it ;) )

[Edited on 21-6-2014 by pepsimax]
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TheCopperMan
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[*] posted on 21-6-2014 at 04:24


Interesting, well, it's definitely not the denat EtOH.

PEA has been tried before and this has never been experienced. Only explanation seen is the excess heat and excess NaCl/CuCl2 messin something up.

If re-ran with less CuCl2 (1-2g per 20g) and/or a bit lower initial starting temp it should probably be better.

[Edited on 21-6-2014 by TheCopperMan]
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pepsimax
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[*] posted on 21-6-2014 at 05:16


Do you recommend still using the same amount of nacl with the copper? Ie 1g cu 20g na, or adjust accordingly?
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[*] posted on 21-6-2014 at 06:09


Use only CuCl2...no NaCl is neccessary.

So only 1-2g CuCl2.
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[*] posted on 21-6-2014 at 08:20


Ah, no salt. Thanks, perhaps that contributed to my 'chloroform'. I was looking at a prep for chloroform from ethanol using bleaching powder, I guess something similar must have happened in my flask. Thanks again copper man, although I haven't been entirely successful at least i've been entertained this last week or so ;-)
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[*] posted on 22-6-2014 at 09:02


Presence or formation of chloroform doesn't make sense to me, assuming you aren't leaving out anything important. But... How pure was the nitrostyrene? If there was a fair amount of benzaldehyde contamination, it could have been reduced to benzyl alcohol, which in turn may have been chlorinated to benzyl chloride. It has been a while since I had any benzyl chloride, but if I remember correctly, it smells vaguely "chloroformish."

Also, impure starting material would at least partially explain the low yields ;)
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[*] posted on 22-6-2014 at 13:36


Hey that makes absolute perfect sense, I think you're dead on there. The nitrostyrene was recrystalised but does still have the almond odour. The description on wiki matches.. war gas indeed. The stuff is incredibly harsh on the throat, that's why I presumed chloroform as i've never actually smelt it, just going by appearance and knockout stench, thanks!

[Edited on 22-6-2014 by pepsimax]
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