Ephoton
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lithium amide prep at RT via lithium bronze, OTC dimsyl ions and Reducing agent
lithium amides can form the deprotanation ion of dmso.
a nice easy way to make lithium amide is as follows.
U.S. Pat. No. 5,486,343
EXAMPLE 1
Preparation of Lithium Bronze in Hexane
1.39 g granulated lithium (0.2 mol) were placed in 150 ml hexane in a 500 ml double jacket reactor at 20° C. The ammonia (0.8 mol, approximately 20
liters) was introduced in an amount that it would be absorbed and as far as possible would not escape. The start of the reaction could be recognized
by the heat of the solution and by the discolouration of the lithium surface from silvery to bronze colours. The resultant heat of the reaction was
dissipated by jacket cooling. When all the lithium had liquefied to lithium bronze (after approximately 3 hours), the addition of ammonia was
terminated. A 2-phase liquid solvent system was obtained in which the copper-coloured lithium bronze floated on the surface.
EXAMPLE 2
Preparation of Li-amide with Styrene
11.5 ml (0.1 mol) styrene was added in measured doses within 115 minutes to the 2-phase system of 0.2 mol lithium bronze in 150 ml hexane from Example
1 at a temperature of 20° C. With recatescence, Li-amide and 0.6 mol NH3 (approximately 15 1), which was released continuously, were formed. The
reaction preparation was subsequently stirred until no more lithium bronze floated. The light-grey Li-amide formed a sediment on the base when
stirring stopped; the supernatant hexane solution was colourless and clear. The reaction preparation was filtered by way of a G-3 filter and washed
with 3×20 ml hexane; the filter residue was dried under an oil-pump vacuum at ambient temperature. The lithium amide that was obtained was 5.5 g
white powder; the isolated yield was 98%, the purity 97.5%.
of course the hexane can be substituted with xylene or toluene
 .
styrene to allyl benzene is now very otc.
[Edited on 26-3-2008 by Ephoton]
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jizmaster
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| Quote: |
of course the hexane can be substituted with xylene or toluene
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And the 35 L anhydrous ammonia!? Wouldn't it be easier to make a grignard and use that?
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Ephoton
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I think if you will find that it is a measurement for gas not liquid.
Thats the whole idea no liquid ammonia 35 L of gas is not that much.
35L of liquid and just add some iron salt and you could make over 20 Kg of
amide 
oh and just for the sake of being realy obvious check the
flask size and the fact that the reaction is at RT.
also look at the moles needed and then the density of ammonia
it works out if you want to use liquid ammonia about 5ml
[Edited on 26-3-2008 by Ephoton]
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Ephoton
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This bronze solutions is quite usefull
it is an excellent reductive solution that will reduce alkenes and I also bet
alcohols too. ie instead of adding styrene and getting ethylbenzene add
ephedrine. anyway here are two more pattents that use this process in
various ways.
one sujests the need of low temps. I dont think this is true unless your
using an alkene to suppress the formation of hydrogen.
after reading a bit more on the subject I have come to the
belife that it would be best to do this under argon as
the bronze is very reactive.
WO/2005/080265
EP1238944
personaly I will stick to the above method and also use it for reductions in
future (if it works as stated.)
two birds with one stone
[Edited on 26-3-2008 by Ephoton]
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jizmaster
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So it is! Sorry! I noticed when i read it too that 0.8 mol, 20L is roughly 1 mol, 24L, so it must be gaseous. Missed the flask size though 
So the dimsyl anion will add to styrene, then sulfoxide elimination gives allylbenzene?
About ephedrine, wouldn't the lithium bronze just deprotonate the alcohol though, then be unable to reduce it?
And what the hell is this lithium bronze, and how is it converted to lithium amide with styrene!?
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Ephoton
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good question
I belive the lithium is charged with ammonia ie NH3 this is the lithium bronze.
this then needs to loose a hydrogen atom to make the amide hence the need of
an alkene that is to be hydrogenated.
two in one first a hydrogenation compound then it perciptates a deprotonation compound.
it is stated that if the bronze is heated it will also make the amide via loosing ammonia and hydrogen.
of course the hydrogen is nascant becouse we are going from NH3 to NH2 to make
the amide.
I found these patents by looking to find what happened to the sodium in a birch as I wanted to use an amide to make the dimsyl ions.
this would make it so any birch I did was able to give me
a product to make dimsyl ions.
I think the reduction is pritty much along the same lines as the
birch when useing the lithium bronze. might be a good
idea to add the ephedrine in an alcohol though.
well this is still very new to me but I think thats about the best answer I can give.
as for the dimsyl ion adding to styrene foxy had the answer
to that on the hive.
foxy2
(Distinctive Doe)
07-04-02 00:09
No 328466
Styrene to Allylbenzene
(Rated as: excellent) Bookmark
styrene + DMSO --very strong base (hydride)-- allylbenzene
The Addition of Dimethyl Sulfoxide Anion to Olefins and the Pyrolysis of Sulfoxides
Cheves Walling and Laszlo Bollyky
JOC 29, 2699 (1964)
Abstract
Base-catalyzed additions of aryl-conjugated olefins, styrene, and 1,1-diphenylethylene to dimethyl sulfoxide occur rapidly at room temperature and
give the corresponding methyl 3-arylpropyl sulfoxides in almost quantitative yield. The reaction fails with aliphatic olefins, but occurs with
molecules such as allylbenzene which presumably isomerize before addition. The resulting sulfoxides decompose thermally below 200C, giving
quantitative yields of 3-arylpropenes with no double bond isomerization. The kinetics of sulfoxide decomposition in diglyme solution have been studied
briefly. Decompositions are first order with half-lives (for aliphatic sulfoxides) of 10-30 hr. at 145C, and the reaction should be of general
synthetic value.
Experimental
Reagents were commercial materials unless noted, freshly distilled before use. Dimethyl sulfoxide was distilled from CaH2 under reduced pressure and
contained not more than 0.001% water by Karl Fischer titration.
Di-n-dodecyl sulfoxide was prepared by treating 1 g. of dodecyl sulfide in 15 ml. of t-butyl alcohol with 0.35 ml. of 30%, H2O2 in 10 ml. of t-butyl
alcohol and stirring for 60 hr. at room temperature. The product was recrystallized from ether with m.p. 88.5-89C, yield 97.5%.
The preparations of other sulfoxides are described below.
Addition of Dimethyl Sulfoxide to 1,1-Diphenylethylene.
The dimethyl sulfoxide anion was prepared by dissolving 1 mole of sodium hydride in 400 ml. of dimethyl sulfoxide. One equivalent of
1,l-diphenylethylene was added at 25C; the mixture was quenched with water, extracted with ether, and dried; and the methyl 3,3-diphenylpropyl
sulfoxide was recrystallized from 3:1 ether-hexane. The product, m.p. 70-71C.
When the crude sulfoxide from a similar experiment was distilled under reduced pressure at 150-200°C, 3,3-diphenyl-l-propene, characterized as
described earlier, (9) was obtained in a 96% over-all yield. Other experiments listed in Table I were carried out similarly, except that, when
gas-liquid chromatography (g.l.c.) was used for analysis, the extracted sulfoxide solution was injected directly into the g.l.c. instrument and
underwent immediate pyrolysis in the injector block which was maintained at 250C. The identifications of diphenylmethane and 1,1-diphenylcyclopropane
were made as in our previous paper.(9)
Addition of Dimethyl Sulfoxide to Styrene.
Addition to styrene was carried out in the same manner under conditions shown in Table II. The intermediate methyl 3-phenylpropyl sulfoxide, m.p.
43-44C, had the expected infrared and n.m.r. spectra.
Pyrolysis of the crude sulfoxide gave allylbenzene, identified by infrared and n.m.r. spectra and g.l.c. retention time, and a small amount of
3,5-diphenyl-l-pentene, identified by infrared spectrum.
Addition of Dimethyl Sulfoxide to Allylbenzene.
Addition to allylbenzene was carried out in the same manner under the conditions indicated. The methyl 3-phenyl-2-methylpropyl sulfoxide, m.p.
80.5-81C, had the expected infrared and n.m.r. spectra.
Pyrolysis gave 3-phenyl-2-methylpropene in 92% yield, idcntified by infrared and n.m.r. spectra and index of refraction, n 23 D ~ 1.5072, lit. 1.5075.
Table II: Addition of DMSO to other Olefins
--------------------------------------------------------------------
Styrene
Temp: 43C Time:0.5h Base:1.0
Yeild: Allylbenzene 62% (3,5 diphenyl)-1-pentene 28%
Styrene
Temp: 25C Time:0.3h Base:0.22
Yeild: Allylbenzene 71% (3,5 diphenyl)-1-pentene 19%
Styrene
Temp: 25C Time:0.3h Base:2.2
Yeild: Allylbenzene 88% (3,5 diphenyl)-1-pentene 2%
Note: Slow addition of dilute styrene to basic solution.
Allylbenzene
Temp: 25C Time:0.5h Base:1.0
Yeild: 3-phenyl-2-methylpropene 92%
3,3-Diphenylpropene
Temp: 70C Time:2.5h Base:1.0
Yeild: diphenylmethane 50% 3,3-diphenyl-2-methylpropene 30%
-----------------------------------------------------------------------
Base Moles/mole of olefin)
(9) C. Walling and L. Bollyky, JOC, 28, 256 (1963).
[Edited on 26-3-2008 by Ephoton]
[Edited on 26-3-2008 by Ephoton]
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Ephoton
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yep this will for sure reduce ephedrine here is a nice paper on reduceing unsaturated
ketones (great for getting ready for the beayer villager after an aldol)
the formular for lithium bronze is Li(NH3)4 hence the loss of
ammonia and the reductive hydrogen.
Lithium bronze as a stoichiometric reagent for the conjugate reduction of .alpha.,.beta.-unsaturated ketones
Richard H. Mueller and James G. Gillick
pp 4647 - 4648; DOI: 10.1021/jo00418a024
http://pubs.acs.org/cgi-bin/abstract.cgi/joceah/1978/43/i24/...
the do say do it in the cold though but as we can see above the reagent can be made at room temp. I would say it is possible to do this with out going
so damb
cold. but even then dry ice was never the problem of the birch it was always the
damb ammonia.
another patent stating this can be done at room temp.
United States Patent 6756024
http://www.freepatentsonline.com/6756024.html
here it is stated that (+)-carvone was reduced to (-)-Dihydrocarvone with the bronze compound.
http://library.wur.nl/wda/abstracts/ab1601.html
something else of interest this will also work for sodium
here is a link that states that sodium also forms a bronze
and it is the loss of the electron (solvation in ammonia)
that makes it blue. with this route we are not giving the
alkali metal enough solvent to loose the electron in the first
place.
http://jchemed.chem.wisc.edu/JCESOFT/CCA/CCA8/MAIN/8/98/07/m...
I belive the key to useing the bronze at RT for a reduction agent is to make sure you keep it in the solvent you make it
in. dont isolate it just stir and add ephedrine in alcohol.
of course this must all be anhydrous. probably have better
results though if it was on ice as you will be able to keep more
ammonia in the solvent. if isolated it will need to be kept under
the boiling point of ammonia. this way it will not boil the
ammonia off the lithium.
a very safe birch
[Edited on 26-3-2008 by Ephoton]
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Klute
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| Quote: | here is a nice paper on reduceing unsaturated
ketones (great for getting ready for the beayer villager after an aldol) |
I'm afraid i don't see your point here. The bayer villiger oxydation, needs to be performed on a unsaturated ketone to give you an enol ester, which
tautomerises to a ketone upon hydrolysis. Reduction to a saturated ketone, and subsequent BV oxydation, would give you a "regular" ester which would
give a carboxylic acid upon hydrolysis.
On the second hand, this reaction can be used to prepare saturated ketones like the "raspberry" ketone, from the unsaturated ketones formed between
p-hydroxybenzaldehyde and acetone. Maybe you are confusing the two pathways, to completly different, but nice smelling products. Using Li metal would
be a little expensive for that reduction though, as either atm catalytic hydrogenation over Pd/C or better Rh/Al2O3 or NaBH4/CoCl2 reduction in
presence of Sodium Dodecylsulfate equally work.
For the Li amide: depending on the ketones used, wouldn't the amide form enols as soon as it is formed? In that case it can't be recovered as
hydrolysis is needed to recovered the saturated ketones.
I guess this can be usefull for those with a good Li supply. Or that can buy Li batteries and are willing to kill some time
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Ephoton
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your right klute sorry
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