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Author: Subject: Experimental: Alternative to Al/Hg - the Al/Cu
pauldir
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[*] posted on 16-8-2014 at 03:34


... first " HELLO COMMUNITY ! "

(my english is bad ..)

@ TheCopperMan

you say we must check the ph from the steam destillation. Where must i check the ph correctly ? In the reaction flask or in the flask with the amine freebase + water
(after the steam destillation, the freebase swim on the top of water when it cooled)

for my understanding, when i do a steam destillation (easy way) i fill my reaction flask with NaOH, that i get a ph ~12, then i start heating ~ 100°C for boiling.
The water takes the freebase with the steam to the outher flask (when i start, this flask is empty ;)), from time to time i add some more lye to the reaction flask
(ph must about 12 here). Where can i now see it is finished ? All freebase is gone ?

i hope you all can help one more nooby. thank you and have a nice day !

[Edited on 17-8-2014 by pauldir]
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TheCopperMan
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[*] posted on 16-8-2014 at 15:33


@crystal
No attempt with Ga-salts yet, only Ga metal and it works pretty good. See http://www.sciencemadness.org/talk/viewthread.php?tid=31127

@pauldir
Check PH of the distillate, it should be basic, indicating amine. Then simply add acid until neutral and evaporate the water.

As for knowing when all freebase has distilled over, you need to occasionally check the PH of the drops as they come over. Once the drops coming over are neutral or close to it, all amine has been distilled over.
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pauldir
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[*] posted on 17-8-2014 at 02:00


thank you @TheCopperMan
..... ahhh i hope i understand now. The NaOH alone comes not over because it is dissolvably in water. Right ?


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lullu
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[*] posted on 17-8-2014 at 02:27


The NaOH will not end up in the receiver.
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[*] posted on 17-8-2014 at 09:17


....the method with cooper sulfate and sodium chloride was tried as posted , after adding the dissolved copper sulfate and sodium chloride the reaction was violent and made an impressive volcano trowing out most of the aluminum....I had a catch plate and return all the material back in and continued with the process .......

i was not able to get much back since i saw most of the aluminum when i filtered......next time when i try it with mny beta nitrostyrene i will heat the solution then pour in in a bucket and then add the copper sulfate and sodium chloride and let it rise as much as it wants since the polypropolene will take quite a bit heat ....

once it calms down i will pour it back in my flask and continue with the reaction or use a RBF ten times head space and run the reaction with no fear of volcanoes ocurring and perhaps the reaction will run its course without andy interruption....solo




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Templar
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[*] posted on 17-8-2014 at 21:48


I tried this reaction as per the writeup from copperman. I made sure I followed it very closely. I let it reflux for 24hrs after the initial reaction had died down.

After basification and extraction with toluene, I received no yield.

I have to try it again, but I am viewing this synthesis with a heavy dose of skepticism. The internet appears to be full of writeups that promise a lot and give nothing... although it is yet to be seen if this is undoubtably the case...

The fact that no one else has succeeded with this reaction except copperman is worrying.

It will be very dissapointing if it doesnt work a second or a third time, and if no one else can confirm results :mad:

Please note, I'm not saying it doesnt work yet, I'm just saying that it isnt promising when it is run with pure reagents closely following the writeup, and doesnt give anything, and when even nitromethane hasnt been successfully reduced from other members reports.

The substrate in question was a dimethoxylated nitrostyrene.




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pepsimax
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[*] posted on 17-8-2014 at 22:43


The reaction definitely does work, with beta nitrostyrene at least but I can't get consistent results.

There are two main issues I think....

A, stirring. It's hard to keep the Al under. My best results are when, by luck, the egg bar managed to hold it all down. Overhead stirring is best. But, I made a galluminium alloy which sank when broken up, this worked perfectly with copper chloride.

B, temp. I feel there's a point where if the temperature drops below, the reaction dies and won't restart. Unfortunately it seems to be very close to the bp of ethanol. My highest yielding runs have been very violent and the solvent has boiled away. When I kept the temp stable below 72 in the initial reaction i got no product.


Maybe a higher bp solvent would help, n-PrOH? I can't seem to find any but it looks a good candidate to me, primary alcohol,protic bp 97'c

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Templar
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[*] posted on 18-8-2014 at 00:31


Quote: Originally posted by pepsimax  
The reaction definitely does work, with beta nitrostyrene at least but I can't get consistent results.

There are two main issues I think....

A, stirring. It's hard to keep the Al under. My best results are when, by luck, the egg bar managed to hold it all down. Overhead stirring is best. But, I made a galluminium alloy which sank when broken up, this worked perfectly with copper chloride.

B, temp. I feel there's a point where if the temperature drops below, the reaction dies and won't restart. Unfortunately it seems to be very close to the bp of ethanol. My highest yielding runs have been very violent and the solvent has boiled away. When I kept the temp stable below 72 in the initial reaction i got no product.


Maybe a higher bp solvent would help, n-PrOH? I can't seem to find any but it looks a good candidate to me, primary alcohol,protic bp 97'c



I used a large stir bar and aluminium turnings. Kept reaction rate consistent and under control. Works well for Al/Hg.

What yields have you gotten so far?




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pepsimax
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[*] posted on 18-8-2014 at 00:49


Well, with al turnings I got 0. Try with large flat strips like coppwrman suggested.

Yields have been 0-75%, sorry that isn't much help! Following the orginal post I always get something, though the side products vary in identity and quantity greatly. Your substrate must be very pure or side reactions compete...

When you have large flat strips you can see the copper plating on to it, I see that as a good sign, never had a complete failure like that.

Have you got any gallium? Look in coppermans other thread and try what I posted with copper chloride, works every time and is very clean!

Ps- what solvent did you use? Ipa doesn't work, ethanol or methanol does. Replicate the original post and I think it will be unlikely you won't see product.

[Edited on 18-8-2014 by pepsimax]
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pauldir
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[*] posted on 18-8-2014 at 01:29


Quote: Originally posted by pepsimax  


Have you got any gallium? Look in coppermans other thread and try what I posted with copper chloride, works every time and is very clean!

[Edited on 18-8-2014 by pepsimax]


in a smal test, this was the same here. First test only with al/ga, the reaction will not realy start, than i add some copper chloride and the reaction looks great for me. now i need some gallium for real testing

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pepsimax
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[*] posted on 18-8-2014 at 02:12


Excellent, glad to hear one of my suggestions helped! Let us know how it scales, I've run out of gallium too!
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[*] posted on 18-8-2014 at 03:14


Hmm I will try the aluminium strips then. It seems very strange though that Al turns would not work.





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[*] posted on 18-8-2014 at 03:31


Good luck. Make sure to let it run as hot as possible whilst keeping it in the flask. If you still don't have any luck, the gallium/al/copper method will work in that scale, but you'll probably have to tweak it for large amounts
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TheCopperMan
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[*] posted on 18-8-2014 at 03:56


Templar : Did you try a regular Al/Hg on the styrene?

If a regular Al/Hg doesnt work then odds are Al/Cu or Al/Ga wont work either.
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pauldir
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[*] posted on 18-8-2014 at 04:35


@TheCopperMan
is it possible that you post some pictures from the work, step by step suitable to your first postings ? (use a tool like Exif Tag Remover for erase metadata from pictures)



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[*] posted on 18-8-2014 at 14:23


Yes the nitrostyrene was well purified, light orange xtals.

A more cimprehensive writeup would likely help





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[*] posted on 24-8-2014 at 13:40


I can confirm that it works. I haven't had luck when I tried to reduce nitromethane but I did reduce b-nitrostyrene. I would not say that I was successful, because the yield was really low. I have to say thou that I just wanted to do a little test and I didn't make much effort. After some optimization of the procedure, the Al/Cu couple can be really useful.

Anyway this is how it went:

I mixed GAA, IPA and water. 100, 35 and 35 ml of each respectively. To the mixture I added 10 grams of CuCl2.H2O and heated it until most of it dissolved. To that I added 12 grams of freshly prepared and still wet (after the water wash) crystals of b-nitrostyrene. I can't tell how much of them there was really. I estimate that something between 6 to 10 grams, closer to 6 I think. After it all went into solution I threw in 10 grams of thick (1mm) Al ribbon. The temperature rose until reflux and kept at that level for 10 or 15 minutes. After it started to drop I just left it and went to eat dinner :) No stirring or reflux was applied. After maybe an hour I basified everything and extracted an astounding yield of about 800mg. Loads of unreacted crystals were on the bottom of the flask. 5 grams of aluminum did not react as well.

My thoughts on it are:

- IPA can be used
- stirring and keeping under a reflux would probably increase the yield and the consumption of Al
- the yield would still suck (it would probably be around 1600mg)
- elemental copper present in the post reaction mixture was clogging my separatory funnel which was really annoying
- GAA may not be the solvent of choice for this reaction. Polsaer used only GAA and water, and got lower yields than I did. I used mostly GAA and some IPA with water, and the results were a little bit better. Maybe running it in a mix of mostly alcohol, without acetic acid, would give even better results. CopperMan used 300ml EtOH, 120ml water, 45ml GAA and claims 70% yields.
- the amount of copper salt needed to activate a certain amount of Al has to be determined.
- the amount of Al/Cu needed to reduce a given amount of substrate needs to be determined as well. I personally do belive that yields around 70% percent can be achieved but the amount of Aluminum and Copper used in the original procedure seems too low. Copper has lower overpotential for hydrogen evolution than Mercury so a lot of it can probably just reduce water instead of the substrate. Also more of the Aluminum is turned into AlCl3 because more chloride salt is used to activate it.
- copper doesn't stick to Aluminum like Mercury does when it forms an amalgam. It falls off not long after it plates the surface of Al. That leads me to think that using thin aluminum with a well balanced amount of a copper salt (enough to plate it but to little to consume it by the formation of AlCl3) could give better results than using thick metal and big amounts of salts.


Lastly I want to say that I'm not a scientist but a hobbyist and most, if not all, of my assumptions can be incorrect. Thank you.



[Edited on 24-8-2014 by Crypto]
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pepsimax
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[*] posted on 24-8-2014 at 18:22


Glad to hear it. Bit scared of copper salts myself, apparently they're incompatible with NM. Know any more?

I just condensed some 3,4-dihydroxybenzaldehyde with nitromethane. Will I have dopamine once it's reduced? By Cu/Al of course ... :)
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[*] posted on 25-8-2014 at 01:09


Apperently Copperman tried it without GAA and got worse results. Maybe just a little is needed. Unfortunately no one can reproduce his results.
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the gay doctor2
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[*] posted on 10-9-2014 at 22:39


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.

I think the copper salts may damage the product. Once the reaction was ready for reflux I carefully added zinc dust. This is very foamy and exothermic.This quenches the excess copper chloride, then you must steam distil out your freebase. Yeild was extremely high, I'm not sure how much exactly as my styrene was brown and impure.

I was expecting nothing, got 3ml which was brominated to some sublime 2C-B. The zinc trick also helps with phenyl-2-nitropropene, though yields are OK with that anyway.

P2NP - CuSO4 50-60%

P2NP - CuSO4, then extra Al
nd CuCl, Zn before reflux - 78%.

There's no way you're extracting the zinc mess efficiently without distillation so don't
waste your time.
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[*] posted on 10-9-2014 at 23:17


Quote: Originally posted by the gay doctor2  
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.

I think the copper salts may damage the product. Once the reaction was ready for reflux I carefully added zinc dust. This is very foamy and exothermic.This quenches the excess copper chloride, then you must steam distil out your freebase. Yeild was extremely high, I'm not sure how much exactly as my styrene was brown and impure.

I was expecting nothing, got 3ml which was brominated to some sublime 2C-B. The zinc trick also helps with phenyl-2-nitropropene, though yields are OK with that anyway.

P2NP - CuSO4 50-60%

P2NP - CuSO4, then extra Al
nd CuCl, Zn before reflux - 78%.

There's no way you're extracting the zinc mess efficiently without distillation so don't
waste your time.


Well done.

So you did the reaction with half the needed aluminium at the start with all the nitrostyrene in solution, then added another half with some more Cu and sodium salts once it had died down?

Then you added Zn once the reaction reflux was complete and then steam distilled by adding water to the post reaction mix, basifying then just boiling it in a distillation setup?

Would you be able to go over your exact procedure as best as possible? Amount of Aluminium at the start, type of aluminium etc? (foil, turnings?)





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the gay doctor2
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[*] posted on 11-9-2014 at 00:33


Hello friend.

I added 5g Al, thick good quality cut into 30 mm2 squares. 4g styrene, 20ml GAA, 150ml MeOH and 30ml water were brought to 70c.

This stirred via large ptfe paddle at high speed in a 1 litre RBF.

After 15 minutes 2.5g CuSO4 and 5g NaCl, dissolved in enough hot water, was added to the reaction. Within seconds an extremely hard reflux began, stirring was kept high and heat turned off. The temperature was carefully monitored and as it began to drop, heat was reintroduced carefully to keep the hard reflux. This shouldtake under 15m to reach.

Now, 750mg CuCl was again dissolved in minimum hot water, 2g of the Al was added and the copper solution as quickly as possible once the Al is in. You may need to reduce the heat for a few mins but still maintain hard boiling.

Once that has died down let stir at 75 for 30 mins. Now add small spatulas of zinc powder until it has all reacted and stopped foaming and getting hotter. I'm not sure how much Iused sorry,just a slight excess of what was needed.

Now reflux for one hour or so. After this filter the unreacted metals, then set up for distillation. Boil off the alcohol,basify, then steam out your product.

There is probably an excess of Al, perhaps reduce the initial portion like you said.

[Edited on 11-9-2014 by the gay doctor2]
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[*] posted on 11-9-2014 at 01:27


Hello friend.

I added 5g Al, thick good quality cut into 30 mm2 squares. 4g styrene, 20ml GAA, 150ml MeOH and 30ml water were brought to 70c.

This stirred via large ptfe paddle at high speed in a 1 litre RBF.

After 15 minutes 2.5g CuSO4 and 5g NaCl, dissolved in enough hot water, was added to the reaction. Within seconds an extremely hard reflux began, stirring was kept high and heat turned off. The temperature was carefully monitored and as it began to drop, heat was reintroduced carefully to keep the hard reflux. This shouldtake under 15m to reach.

Now, 750mg CuCl was again dissolved in minimum hot water, 2g of the Al was added and the copper solution as quickly as possible once the Al is in. You may need to reduce the heat for a few mins but still maintain hard boiling.

Once that has died down, add small spatulas of zinc powder until it has all reacted and stopped foaming and getting hotter. I'm not sure how much Iused sorry,just a slight excess of what was needed.

Now reflux for one hour or so. After this filter the unreacted metals, then set up for distillation. Boil off the alcohol,basify, then steam out your product.

There is probably an excess of Al, perhaps reduce the initial portion like you said.
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[*] posted on 12-9-2014 at 22:17


I'm curious how would the system work with imines. I was planning to give it a try but I haven't got anything to reductively aminate right now.
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[*] posted on 13-9-2014 at 09:32


In-situ reduction of ketone/nitroalkane didn't work for me - I only got aminoalkane
Perhaps with pre-formed imine the reaction works?
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