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haribo
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That may be the case with unsubstituted varients, but it may be a useful route to substituted analogs. Forgive my ignorance, but what are these 2
'well documented' steps? I'm familiar with aldehyde->nitroalcohol->aminoalcohol but not this one. Forgive my ignorance...
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jon
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I'd like to suggest something in the workup of ppa. PPA is a solid at room temperature and the other amine in the workup (benzylamine) of the first
reaction has a m.p. of -46 degress c.; the other nitrogeneous compund formed in abundance (bis-phenyl-1-amino-2-ethanol) is insol. in water as the
hydrochloride, so it formed the third phase during the hcl extraction you saw in the photos.
So here's what you do,( I used this on ephedrine which has this property also) you evap. the Hcl extract. and clean it up with ethyl acetate (make
sure the ethyl acetate is alcohol, and water free it will suck up water you know) then dissolve it into water a minimal amount of water, and add base
(a weak base like NaCO3) then heat this, and extract into naptha (naptha has this property of dissolving aminoalcohols, ephedrines, at elevated
temperatures and when it cools they come out of solution as a solid this works with amphetamines too). so you want to quiclky seperate the phases
before you mixture cools, it also helps to filter the naptha hot before it cools.
this ought to do a really nice job of seperating your amino alcohol from benzylamine without having to fractionate it twice.
regarding acetone solubilty I've seen this parallel with the ephedrines too. the erythro isomers will dissolve in acetone too. you can probably skip
the evaporation of the HCl and just nuetralize it then satuturate it with salt to drive the amino alcohol out.
[Edited on 10-12-2006 by jon]
[Edited on 10-12-2006 by jon]
[Edited on 10-12-2006 by jon]
[Edited on 10-12-2006 by jon]
[Edited on 10-12-2006 by jon]
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jon
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it appears I stand corrected 2-amino1,2diphenylethanol is soluble as it's hydrochloride just like any other amine salt. And it's freebase melts at 146
centigrate did'nt mean to mislead anyone.
it seams though that beta hydroxy amino alcohols can be decarboxylated via the shiff's base of cyclohexeneones not cyclohexanones! as the
intermediatdiate is a condjugated diene of some sort as illustrated in Rhodium's and Wikipeadia, theronine is decarboxylated to amino-propanoic acid,
theronine is a beta-hydroxy-aminoacid as illustrated in Rhodium's mirror. so you can see the utility in this towards serines and the
betamethylserines, the aldol codenseation could be some what sterically hindered but this is a toss up because this is only the case in diaklyl
substitued (alpha-acidic carbons) as you see in typical aldol condensations in this case the alpha carbon on which the dissassociable hydrogen is
located is adjacent to both an imine and a carboxylic group ( the only way steric hindrence can interfere in this case is by ;limiting the
abstractability of this proton which isn't likely to occur sandwhiched between two electron withdrawing moities)
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roamingnome
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New Years Possibilities
1) Tetrahedron Letters
Volume 44, Issue 12 , 17 March 2003, Pages 2565-2568
ScienceDirect - Tetrahedron Letters : Rapid cyclopeptide analysis by microwave enhanced Akabori reaction
As a bonus discussed in that issue, novel indole compounds discovered in corals. As if global warming wasn’t killing them fast enough
2) Highly diastereoselictive synthesis of 1,2-oxazolidines under thermodynamic control using focused microwave irradiation under solvent-free
conditions
http://rsc.org/delivery/_ArticleLinking/DisplayArticleForFre...
3) Endocannabinoid Metabolomics: A Novel Liquid Chromatography–Mass Spectrometry Reagent for Fatty Acid Analysis
Abstract
We have synthesized 4,4-dimethoxyoxazoline derivatives of several fatty acids associated with the endocannabinoid metabolome using
tris(hydroxymethyl)aminomethane in a 1-step reaction by microwave irradiation. The derivatization incorporates a nitrogen into the final product,
which allows for improved detection by liquid chromatography–mass spectrometry in positive atmospheric pressure chemical ionization (APCI) mode.
Palmitic and oleic acid derivatives show a 200-fold increase in sensitivity compared with the free acids when analyzed in negative-mode APCI. In
addition to improving sensitivity, the oxazoline derivatization creates a similar ionization response for the fatty acids tested, which simplifies
their quantitation. Fatty acid oxazoline derivatives can be detected using the same conditions optimized for the endocannabinoids, which allows for a
simultaneous quantitation of the entire endocannabinoid metabolome.
Keywords: fatty acids, LC-MS, metabolome, oxazoline derivatives, microwave synthesis
4) Process for microwave chocolate flavor formulation, product produced thereby and uses thereof in augmenting or enhancing the flavor of foodstuffs,
beverages and chewing gums
Document Type and Number: United States Patent 5041296 Link to this Page: http://www.freepatentsonline.com/5041296.html
Abstract: Described is a process for carrying out microwave production of a chocolate flavoring product, the product produced thereby and foodstuffs,
beverages and chewing gums containing said product. The process comprises the steps of: (a) providing a composition of matter consisting essentially
of precursors of a chocolate flavor (e.g., sugar, leucine and phenyl alanine) and a solvent capable of raising the dielectric constant of the reaction
mass to be heated; (b) exposing the mixture of reaction precursors to microwave radiation for a period of time so that the resulting product is caused
to have a chocolate flavor; (c) providing a foodstuff, chewing gum or beverage base; (d) admixing the chocolate flavor reaction product of (b) with
the foodstuff, beverage or chewing gum base.
#4 touches on benzaldehyde a bit as well so I felt they all relate to amino alcohols and the Akabori reaction, and since a second look at this post
mixed with mania in regards to microwave enhanced chemistry got me thinking about it.
Lets put it this way if I had benzaldehyde on me I would have mixed it with alanine in the microwave already….
Happy news years where ever you are….
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roamingnome
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acquired artifical flavor( benzaldehyde) in ethanol and water
dewatered 2X 65ml portions in dry MgSO4
poured this into a excess of l-alanine in silca gel
irradiated first portion. Some liquid boiling assumed to be ethanol.
going in cherry smell coming out no smell.
irradiated second portion to same affect.
assuming that nothing can be that simple desire at least an IR to analyze whats in there.
Fractal number of possible experiments now. Acidic or basic conditions. Alumina support or solvent, maybye its a two step reaction ..... ahhhhhhh
unfortunately im bogged down in the synthesis of Bz, its smells too good to be a "bad guy", why is an aromatic ring bad.
carbon atoms ... are bad.... do you have a licence and permit for those carbon atoms?
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jon
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can you describe the colour changes did it go through the same changes to burgandy? also was there vigorous bubbling? any other observations?
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Hilski
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The diastereoselectivity (is that even a word?) of this reaction is very appealing, as is the notion that when equimolar amounts of reagents are used,
little or no post reaction workup is required. Whether or not all of these findings are applicable to reactions with amino acids as opposed to amino
alcohols is yet to be determined I guess.
I will try this once I get some alanine.
[Edited on 3-1-2007 by Hilski]
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roamingnome
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As per your sound advice jon,
I used a thermometer to ensure the temperature of the the sandy mix acheived 160 degrees centigrade.
Very sharply at that temp a mildly choking cloud of white smoke began pouring out of the microwave
The white mass had turned yellow
Due to the uneven heating of the poorly crafted test some areas where very yellow to a brownish color in one area.
Since alanine can form crystals its to soon to say that i did see a shimmery crystal look to the silca gel that was not appearent with just the
powered alanine silica mix before the test.
Finally i hope to use pure IPA to flush out the formed whatevers hopfully leaving behind most of the alanine for the next run.
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Hilski
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| Quote: | | poured this into a excess of l-alanine in silica gel |
Just out of curiosity, why are you using silica gel? I see no need for it in this particular case, since there shouldn't be enough water in the
reaction to make a difference. Or are you using it because of the alcohol still present from the almond flavoring you used?
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roamingnome
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become the molecule
jon mentioned this as well...
since it realases its water at the temps in question
doesnt it have catalytic properties, lewis acid zones?
i dont know, formulation chemistry is fun but challenging becuase 1 drop of an opposing solvent can change the whole system.
im referring to the phtocatalytic (400nm) oxidation of styrene in water. the reaserchers found small amounts of other solvents disruputed the said
mechanism. intersting way to benzaldehye...
anyway please put your thinking caps on and help figure this out. Nicoderms pictures help for sure. It may not deleiver the yields in the end, but
with the number of possible variables i bet something can work here.....
i mean the skys the limit..... ethylene glycol, xylene, driped in benzaldehyde, or excess benz.... summoning all synthetic method chemists
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jon
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I dont' think a lewis acid will serve you, in this case the reaction depends on proton abstraction which uses a base, the base is formed insitu that
being the imine, but another abstract mentions the use of pyridine.
try using the extraction method cycloknight used with toulene, I'm not sure but i think alanine is soluble in alcohols.
extract everything into a non-polar like xylene or toulene, filter, and extract this into an acid. then work this up like cycloknight described.
and as for the use of an alcohol solvent in an aldol condensation the alcohol will add to the aldehyde to give an acetal, this will block the
aldehyde's reactivity.
And if you study cycloknight's result's he says using excess alanine gave a lot of benzylamine i think having a molar deficiency of aldehyde and
having a lot of water kicking around led to this result, but then also he dripped in the aldehyde too.
I like the idea of using a basic heterogeneous catalyst as both a support and a catalyst, some other microwave reactions use different clays like
montmorillite and such as supports in lieu of a solvent, alumina is a basic support.
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roamingnome
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nice.... i will try alumina.
preventing tautomerism is a good idea no?
i saw that alanine is not soluble in ether or non polars
but how about ppa feebase solubitly in ether.... me no find on the net...just FDA recall infomarion....
"review aldol chemistry gnome becuase blabbering"
[Edited on 4-1-2007 by roamingnome]
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jon
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Rhodium's website will give you a lot of data on PPA.
Tautomerism is going to happen in this reaction the only way you're not going to get tautomerism is if you use n-methylalanine which will give an
enamine and the double bond will be fixed.
yes PPA is soluble in ether, I would'nt waste good ether on it's extraction.
Identification of 2-amino-1-phenyl-1-propanol
dl-Norephedrine dl-Norisoephedrine
Freebase mp 104-105°C mp 71°C
Hydrochloride mp 192°C mp 169°C
The product was a very viscous, colorless liquid which solidified on standing, mp 46-50°C. When dry hydrogen chloride was passed into an ether
solution, a gelatinous precipitate resulted, which hardened on standing. This character of precipitate was attributed to the rather complex mixture of
isomers, since an authentic sample of l-ephedrine yielded well formed crystals. A better product could be made from the base by treating it with
concentrated hydrochloric acid to the end point of methyl red indicator, evaporating under reduced pressure, and recrystallizing from butanol-ether
(50:50 v/v). The white crystals (mp 134-137°C) gave 18.87 and 18.89% chlorine by Fajan's method (theory 18.91%). The neutral equivalent of the free
amine was 155 (theory 151). The material is therefore believed to be a mixture of dl-norephedrine and dl-norisoephedrine. These two compounds are
diastereoisomers and the physical constants can be read in the table.
After four fractional crystallizations from absolute alcohol it was possible to obtain a hydrochloride mp 192°C. The melting point of a mixture of
this compound and norephedrine hydrochloride was 192°C. Thus, it is possible to separate the components of the mixture by fractional crystallization
but the yield is low. The method of Nagai and Kanao, which utilizes the greater solubility in ether of norisoephedrine to separate the isomers, was
tried on the free base. After four crystallizations, the amino alcohol melted at 72-75°C. Since the original base mixture melted at 46-50°C, the
difference in solubility is evidently not great.
The mixture of stereoisomers obtained in this synthesis was tested for physiological action by two manufacturers of pharmaceuticals who compared it
with norephedrine hydrochloride and found it to have a similar effect on the blood pressure. The work of Jarowski and Hartung already has been
mentioned.
just extract it into xylene, or toulene and work this up, as you see here you can use the ether as a recrystalization solvent.
about using alumina as a support does'nt this react with COOH to give a salt?
If it does this too would defeat the pupose of the reaction, as you might get a serine but it would not decarboxylate.
Something to look into I'd investigate a support that is either inert, or is basic but does'nt tie up the COOH end of the molecule.
[Edited on 3-1-2007 by jon]
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roamingnome
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Stop the press
check out this little wipper snapper
http://www.organic-chemistry.org/frames.htm?http://72.14.253...
http://www.scs.uiuc.edu/chem/gradprogram/chem435/fall05/Hoyt...
oh wait... im a morron.. ill admit it this time.. but i will post it anyway as a lesson in my own manic retardation.
can we squeeze this together a bit, little nip tuck?
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Ephoton
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I have an idea guys. its the temp that does it. under 160 its all benzyl but at the right temp it works. well the microwave doesnt go long enough and
most of the reaction is done by 2 min. so heat the mix before putting it in the microwave. pritty obvious realy.
e3500 console login: root
bash-2.05#
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Ephoton
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about that acetyl do you realy think ethanol will do this. I dont its in the patent as being a solvent for aldehydes in the reaction. possible if you
did the origonal chocalate reaction with it pre heated it would get higher yeilds as well. another question does benzaldehyde azeotrope with ethanol
as this would be a problem at these tempretures
e3500 console login: root
bash-2.05#
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roamingnome
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Ephoton: i think your elduing to activation energy
the amine of alanine adding to the aldehyde should happen more easily, but the decarboxyation might require that extra energy.
******
Dry gasing of the solvent afforded a modest amount of white/cream colored globuls
The ratio of solvent to actaull product was too much though.
At the time it was rather dissapointing with the feeling that a lava lamp would have produced the same enjoyment, but reading that "When dry hydrogen
chloride was passed into an ether solution, a gelatinous precipitate resulted, which hardened on standing" this is pretty much that.
Unfortunitaly the mechanism of this reaction is complex in that by products are going to form. There might be a reaction pathway to discover here, but
i think l-pac is still me first love.....
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jon
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in the workup you did'nt give much detail as to how you worked it up and what you recovered.
if you simply gassed the extract from the reaction without partitioning it with dilute HCl it's concievable that what you have is a salt of the
shiff's base of the end product.
As to acetal formation I stand corrected aldol condensations catylized by a strong base have used solvent systems like ethanol/water, a strong acid or
base will split up an acetal (ketal or hemiketal) I don't know about this scenario though a strong base is'nt employed in the reaction, but it's worth
a try (maybee a high boiling alcohol like ethylene glycol, propylene glycol, or even glycerin would work)
there are three amines that you will isolate from the reaction mixture (benzylamine, 1,2-diphenyl-2-amino-1-ethanol, and norephedrine) the former two
are insoluble in water but norephedrine is soluble about 5 grams/100ml in water as a freebase.
this would allow for a novel extraction technique to be employed, the aqueous containing the norephedrine can be titurated and reduced in volume and
worked up a number of ways.
Procedure Dispense 200 µL (210 mg, 2.0 mmol) of benzaldehyde directly into a clean, dry test tube (13 x 100 mm), and then add 1 mL 95% ethanol and a
magnetic spin vane. Clamp the test tube to a ring stand, centered above a hot plate/stirrer and start stirring (the hot plate will not be used for
heating!). Add 75 µL (59 mg, 1.0 mmol) acetone, 1 mL 3 M NaOH and stopper the test tube. Stir the reaction mixture at RT (∼20°C) for 30
minutes. Note the appearance of product as a yellow precipitate. Vacuum filter this precipitate and wash it thoroughly with 3 x 1 mL of cold water.
Determine the weight and melting point of the crude sample, and then recrystallize it from ethyl acetate. Once your sample has air-dried (allow 15
minutes after recrystallization) obtain the weight and melting point of purified product and calculate the percent yield. Take an IR spectrum ofthe
recrystallized sample.
product: 1,5-diphenyl-1,4-pentadien-3-one
[Edited on 10-1-2007 by jon]
[Edited on 10-1-2007 by jon]
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roamingnome
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http://www.chem.utoronto.ca/coursenotes/chm443/paper1.pdf
this article pretty much eludes that alanine forms the schiff base with aldehyde at room temperature in DMSO ..
the adding of the second benzaldehyde is where i begin having more questions about how it forms and how stable it is etc.
It seems like its the "committed"step of the reaction mechanism.
in the final step of the reaction a H2O molecule must add to break off the benzaldehyde and leave the desired amino alcohol
if tautomerism occurred is this bond flip dynamic back and forth, or since its a more substituted double bond and thus more thermodynamically
favorable does it get locked.
my hope is that DMSO can form this "committed" step intermediate at near room temperature thus drastically preventing undesirable tautomerism.
i do know that isomerizing the terminal double bond of some olefins to the more substituted iso form takes considerable heat and catalysts
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jon
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no thermodynamicaly favorable just means it's a reversible equilibrium.
DMSO or any polar compound is going to raise the dielectric constant of the reactants, try it and report back it's all guesswork until you get
empirical information, ie. try it.
maybe do some research using keywords "sovation effect" (the effect a solvent has on a reaction system) with respect to aldol type reactions.
that abstract stated in German to warm with ethanol maybe a high b.p. alcohol would do it? who knows.
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roamingnome
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oh snap
First of all im not posting these links just to be cool and think that im saving the whales with my link posting. Instead mechanistic insights are
manifested. Precious yields need to be increased.
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/1954/76/i05/...
the classic I read to late… no one had even reported a failure of this with alanine? Yes it is sterically hindered, but the clue here is alkaline.
Equal molar amount added based on added aldehyde
http://www.rsc.org/delivery/_ArticleLinking/DisplayArticleFo...
gotta love the perkin people, thanks perkins people
again alkaline to …decarboxylate… ahhhhh
http://www.turpion.org/php/paper.phtml?journal_id=rc&pap...
who can tap into the Russian reviews, they seem like a wealth of info. If I had 2000 dollars for the membership Id hook it up, but alas…..
gleaning from google cash alone we see a 3 time molar excess of alkali to decarboxlate….
Salt is also known to aid decarboxylation as well. The lower the temp the better right
Then back to the glycine paper, the people add acid to hydrolyze the imine and recover half of the aldehyde.
Mechanistic gurus feel free to lash out at me… the worst I can do is try to bite off your kneecaps
1) 1 mole aldehyde added to one mole alanine in DMSO ( I did observe that alanine in DMSO when added benzaldehyde precipitated a fluffy gummy like
solid that did not look like alanine. Since the previous post paper says it forms an imine readily I feel that step can occur quite nicely.
2) 1 mole KOH with 1 mole aldehyde in approx. 5 volumes alcohol is added.
( edited: because a carboanion not cation is the nucleophile which adds to the electrophillic aldehyde group to form a carbon-carbon bond)
3) salt or a bit more base can be added to facilitate decarboxylation. The alcohol may be evaporated as well. Monitoring CO2 release would be ideal.
low temp is probably key
4) Finally it is made acidic which recovers aldehyde.
[Edited on 1-2-2007 by roamingnome]
[Edited on 1-2-2007 by roamingnome]
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solo
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Reference Information
Bipyrroles, furyl- and thienylpyrroles
S E Korostova (deceased), A I Mikhaleva, B A Trofimov
Russian Chemical Reviews 68 (6) 459 ± 482 (1999)
Contents
Introduction 459
II. Methods of synthesis 459
III. Reactivity 471
IV. Prospects for the use 479
V. Conclusion 479
Abstract
Data on the methods of preparation of bipyrroles and
furyl-, thienyl- and selenienylpyrroles are summarised and described
systematically. The reactivity and the prospects of application of
these compounds are discussed. Particular attention is paid to a new
convenient one-step method for the synthesis of hetaryl-substituted
pyrroles starting from alkyl hetaryl ketoximes and acetylene. The
bibliography includes 191 references.
Attachment: Bipyrroles, furyl- and thienylpyrroles.pdf (450kB)
This file has been downloaded 1731 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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roamingnome
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carboanions
http://www.siue.edu/~tpatric/cban.pdf
dont be dumb like me, read about carboanions
favorite quote from, "imines are used because there is no competition for adol reactions"
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roamingnome
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time to brakeout those molecular models...
J. CHEM. SOC. PERKIN TRANS. 11 1986
“New Model for the Addition of Carbanions to Carbonyl Derivatives in the Absence of Chelation Control”
Our results suggest that the a-silyl carbanion behaves as a free carbanion, or more likely as a very loose ion-pair.. Phenylmethanide anions with
bulky a-alkyl groups behave as loose ion-pairs. The phenyl(sily1)methanide anion, by analogy, would be expected to be loose-ion-paired, or approaching
the free ions, as there is greater charge delocalisation in this ion, and HMPA is a powerful ionising solvent. Therefore, in our system, a relative
insensitivity to counterion, M+, is not unexpected. It is also clear from the insensitivity to RO- in the carbanion- forming step that the a-silyl
carbanion is essentially completely formed before addition to the carbonyl group takes place.
The Wittig reaction, in which the first step is reversible, is highly susceptible to salt effects. Wittig reactions are similarly highly
solvent-dependent, being particularly sensitive to protic solvent. In the case of the Peterson reaction, protic solvents cannot be used, as they
rapidly quench the a-silyl carbanion
frustrated by poor solubility and usually low yields of stilbenes, and are considered unreliable. Some other solvent systems are shown in Table 6
Dimethylsulphoxide coming in at 99%
The model that we are about to describe is most applicable to the initial stages of an addition where the approach angle is at least 109" and the
deviation from planarity in the carbonyl compound is minimal. As the transition state becomes inter- mediate-like then the relative energies of
possible intermediates assume a greater importance. Previous models for the addition of non-enolate carbanions to carbonyl compounds have concentrated
on the anion attacking at 90" to the carbonyl framework. This approach leads directly to a comparison of the stabilities of diastereo- isomeric
intermediates. The major problem with that model is that it completely fails to account for the so-called 'erythro- selectivity' of carbanion
additions. The seminal work of Burgi and Dunitz l9 and Baldwin has forced a reappraisal of any model for nucleophilic attack at carbonyl groups. It
has been shown convincingly that nucleophiles attack the carbonyl group approximately in the plane of the C-0 n-bond and with a Nu-C-0 angle of about
109". It is therefore misleading simply to analyse conformations of intermediates. The initial steric interactions should be analysed, as shown in
Figure 1. We postulate that one interaction will be more important than the other two,
the first, major, steric influence will result from interaction amongst R', R, and H. This primary steric influence is a direct consequence of the
carbanion attacking at an angle greater than 90". The most favoured orientation for attack will be that in which the primary steric influence is
minimised. The steric outcome of the reaction is then determined by the relative extents of the secondary steric influences; the interaction of R2 and
R3 with R. If we apply this to the reaction between PhCHSiMe, and PhCHO, two transition states can be drawn, one leading to cis- stilbene and the
other to trans-stilbene, as shown in Scheme I. The primary steric influence is minimised by placing the anion hydrogen atom in the most hindered
position, between the aldehyde phenyl group and hydrogen. The major secondary steric interactions are between (a) the benzaldehyde phenyl
--------------------------------------------------------------------------------
Bulky anions, such as PhCHC(CH,),, induced Cannizarro reactions with aldehydes (further evidence that the steric demands of the SiMe, group are not
unduly large), and, with all anions, enolisable ketones underwent aldol condensations preferentially.
In summary, a general rule may be enunciated. Consider the irreversible addition of a carbanion &ML to a carbonyl compound
S'L'C=O, where S, M, and L represent small, medium, and large groups, respectively. The stereochemical outcome of the reaction is determined by two
steric influences, in the absence of chelation control. As a consequence of attack by the carbanion at 109" to the carbonyl compound the primary
influence is such that the smallest carbanion ligand, S, is disposed between L' and S'. The most favoured disposition of the remaining ligands is with
M and L1 and L and S'gauche.
Page 5
www.iupac.org/publications/pac/1979/pdf/5101x0139.pdf
until the red color of the carbanion had disappeared…..
http://www.arkat-usa.org/home.aspx?VIEW=MANUSCRIPT&MSID=...
Formation of carbanion on addition of a strong base to the THF solution of 2 can be followed by the appearance of an intense orange-red color
http://www3.interscience.wiley.com/cgi-bin/abstract/10403982...
since the original red color of the carbanion….
Polymer Volume 46, Issue 18 , 23 August 2005, Pages 6910-6922
The red color of the polymeric solution was attributed to a carbanion
For a more exhaustive paper
The Role of Carbonium Ions in Color Reception
http://www.jgp.org/cgi/reprint/48/5/753.pdf
I thought at the time this color was from like benzylamine or some other double bond system, but it was a truely magnificent red solution. I wonder…
This akabori reaction seems has every thing going for it here… hydroxide probably wont be best as base though…
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jon
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I'm a little confused you said you did a run in DMSO and got mostly benzylamine.
In another paper (chem beritche) I don't understand german fluently but they use a similar system (solvent with a high dielectric constant and
aprotic) nitrobenzol zie germans called it and got guess what, benzylamine.
It's on rhodium's mirror I stumbled upon it at the university today too.
these other systems use ethers like thf with the lone pairs exposed due to steric factors to stabilize the carbanion ethers may be it high boiling
ethers like glycol ethers and what not they are aprotic don't have very high dielectric constants but the lone pairs on the oxygen contribute to
carbanion stabilization which is what we want in this reaction, If what you said about the DMSO route being a really good synth for benzylamine it
appears solvents with high dielectric constants promote hydrolysis of the intermediate (as in the case of nitrobenzene solvent systems alluded to in
the chem. beritche paper) did you do any quantitative analysis of the products?
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