Author Topic: Birch using Na+EtoH ??  (Read 1365 times)

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AbSoLuTe

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Birch using Na+EtoH ??
« on: October 27, 2001, 05:11:00 PM »
Was reading 'Advanced organic chemistry, reactions and synthesis' recently, and on the subject of Dissolving metal Reductions: Addition of Hydrogen, It discusses the reduction of ketones by alkali metals in ammonia OR ALCOHOLS.
It goes on to say a lot more, with the basic gist of it being that Li Na Ammonia Alcohols are all pretty much the same in the reductions. I am keeping this brief, as the search engine had nothing on the subject and it must have been discussed before I think. Anyway any input would be good, as I have a fair bit of Na metal floating around and was thinking 'bout dropping it into some DRY ethanol, see if it turns blue. Might need to add some KOH to the alcohol, maybe, but it would be nice if this worked.
Does some clever bee, higher up the food chain have any xperience with this?
Catch ya's soon.

Still stranger than you!

Rhodium

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Re: Birch using Na+EtoH ??
« Reply #1 on: October 27, 2001, 06:00:00 PM »
No, that won't work. Ammonia (or short-chain amines) are essential for the reaction to work as intended. Sodium in ethanol does not reduce benzylic alcohols, but if you first chlorinate the alcohol, the Na/EtOH should work.

foxy2

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Re: Birch using Na+EtoH ??
« Reply #2 on: October 27, 2001, 08:51:00 PM »
If you add several percent ethylenediamine as a promoter it MIGHT work.  No details available this is just a feeling I have from several journal articles I read a while ago.

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jim

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Re: Birch using Na+EtoH ??
« Reply #3 on: October 28, 2001, 09:04:00 AM »
Actually, sodium can form solvated electrons in pure ethanol.  I have an old Nature article on it, but the alcohol has to be very cold, ~ -70 C, and degassed of all free radical sacavengers such as O2. 

Adding ethylenediamine, even a little, would help a lot.  So would any othere Birch solvent, like NH3.  I would bet that a cold (~ 0 C) saturated solution of ammonia in ethanol would form a blue solution w/ addition of Na, or Li.  The  solvated electrons would eventually react, so the reaction would have to be carried out quickly.  The yields would suffer, but still would be better than a RP/I2 reaction.

AbSoLuTe

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Re: Birch using Na+EtoH ??
« Reply #4 on: October 28, 2001, 01:21:00 PM »
Hmm interesting, thanks everyone.
So what if I were to bubble NH3 gas thru EtoH (real cold) then try dissolving Na in it, I read that the alcohol is needed as a Proton donator.

Still stranger than you!

hest

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Re: Birch using Na+EtoH ??
« Reply #5 on: October 28, 2001, 03:30:00 PM »
I don't think it will work, newer heard of an birch run in ethanol. Just use NH3(l) as the solvent and to mole of Na to one mole of pfed.

jim

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Re: Birch using Na+EtoH ??
« Reply #6 on: October 28, 2001, 04:17:00 PM »
You have never heard of it because the big wigs in chemstry depts have resources that clandestine chemists do not.

It can be done, but you will havelower yields, ~70%.  Adding the NH3 will work great and the colder the better.

foxy2

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Re: Birch using Na+EtoH ??
« Reply #7 on: October 29, 2001, 05:09:00 AM »
I have an article that says small amounts of ethylene diamine have special promoting properties for solivateing electrons in larger amines like Isopropylamine ect

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megamole

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Re: Birch using Na+EtoH ??
« Reply #8 on: October 29, 2001, 08:21:00 AM »
Care to share some more of this inside information on this subject?

foxy2

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Re: Birch using Na+EtoH ??
« Reply #9 on: October 29, 2001, 09:08:00 AM »
You will like this  :)
It took me a while to find as my collection of references is getting huge and I haven't organized them lately.  I need to purchase some reference organizer software.

US Patent 5675038

(http://patft.uspto.gov/netacgi/nph-Parser?Sect2=PTO1&Sect2=HITOFF&p=1&u=%2Fnetahtml%2Fsearch-bool.html&r=1&f=G&l=50&d=PALL&RefSrch=yes&Query=PN%2F5675038)


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Unobtainium

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Re: Birch using Na+EtoH ??
« Reply #10 on: October 29, 2001, 06:08:00 PM »

I would bet that a cold (~ 0 C) saturated solution of ammonia in ethanol would form a blue solution w/ addition of Na, or Li.




I would bet it has to be a lot colder. I tried this a few months ago at slightly under 0 C and could not get lithium to dissolve in ethanol/ammonia solution. I can't say if Na will work because I'm not allowed to play with explosives. :(  

I'm guessing you have to approach conventional birch temperatures, and if you're going to go through the trouble of setting up to sustain subzero temperature, you might as well just use ammonia.


Free Spitball.


foxy2

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Re: Birch using Na+EtoH ??
« Reply #11 on: October 30, 2001, 10:46:00 AM »
Well look at the patent I posted.

Temperatures at which the reaction can be run vary from -20.degree. C. to 65.degree. C. Preferred temperatures for the practice of the present invention are from 0.degree. C. to 55.degree. C., with the most preferred temperature being at or about room (ambient) temperature. The reaction is run at ambient (atmospheric) pressure, and so, in any case, the reaction temperature cannot be above the boiling point of the reaction solution chosen.

Another advantage is obviation of the need to wait for liquid ammonia or methylamine to evaporate from the reaction mixture after the reduction is completed, as is the case with other reduction conditions. The use of higher boiling amines allows for their recovery and recycling from the reaction mixture.

A still further advantage is that using an aliphatic amine permits solubilization of the organic substrate without ether or tetrahydrofuran which avoids the use of highly flammable ether co-solvents, and also the possibility of two phase reaction mixtures.

Another further advantage is that the reaction may be run at or around room temperature, instead of having the necessity for low temperature apparatus, such as Dewar condensers, and fume hoods to remove ammonia or methylamine as it evaporates. Ammonia boils at -33.degree. C. and methylamine at -6.3.degree. C. while ethylamine, the lowest boiling of the amines useful in the present invention boils at 16.6.degree. and the highest boiling, n-butylamine, at 78.degree.. Room temperature (68.degree. F.) converts to 20.degree. C. n-Propylamine has a bp of 48.degree.-49.degree. C. and isopropylamine has a bp of 33.degree.-44.degree. C.



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AbSoLuTe

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Re: Birch using Na+EtoH ??
« Reply #12 on: October 31, 2001, 11:44:00 AM »
Thanks foxy, nice find on that patent, I am allowed to play with explosives, so am gonna try it with some Na , am sure it will dissolve.
I wonder if I should bubble the Na3 gas thru the alcohol before or after the metal addition?
Any thoughts?

Still stranger than you!