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Hilski
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Acetone can be used as a hydrogen acceptor in liu of acetaldehyde
Acetone can be used as a hydrogen acceptor in lieu of acetaldehyde. Orgnikum spoke of this in another thread.
"Whey and beer wort also stimulated L-PAC synthesis, giving
maximum yield upto 0.78 g L-PAC/100 ml. Similarly
the the yield of L-PAC was increased when acetone was
added to the culture medium as a competitive hydrogen
acceptor, probably making more benzaldehyde available
for L-PAC formation (Yashio 1952). Ose et al. (1960)
reported that addition of acetaldehyde increased the
yield of L-PAC by acting as hydrogen acceptor and
inhibiting hydrogenation of benzaldehyde to benzyl
alcohol and diverting more benzaldehyde towards
L-PAC formation using pressed beer."
That excerpt is from this paper. I can't remember where I got this pdf from, but it is a good read.
[Edited on 16-12-2006 by Hilski]
Attachment: LPAC biosynthesis and industrial applications.pdf (136kB)
This file has been downloaded 4702 times
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Organikum
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Acetone can be used but it requirers the use of much more water as solvent to prevent the toxic effects of acetone and IPA onto the yeast. About twice
as much. And this makes the whole thing a bit unfavorable.
/ORG
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roamingnome
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substitute for ammonium formate the hydrogen donor
J. Org. Chem., 64 (16), 5746 -5753, 1999
Web Release Date: July 20, 1999
Copyright © 1999 American Chemical Society
Microwave-Assisted Rapid and Simplified Hydrogenation
(imine reduction)
Bimal K. Banik, Khaled J. Barakat, Dilip R. Wagle, Maghar S. Manhas, and Ajay K. Bose*
Abstract:
Catalytic transfer hydrogenation has been conducted under microwave irradiation in open vessels using high-boiling solvents such as ethylene glycol
(bp 198 C) as the microwave energy transfer agent. Reduction of double bonds and hydrogenolysis of several functional groups were carried out safely
and rapidly (3-5 min) at about 110-130 C with 10% Pd/C as an efficient catalyst and ammonium formate as the hydrogen donor. Diverse types of -lactam
synthons were prepared by the reduction of ring substituents containing alkene and alkylidene groups or conjugated unsaturated esters. Cleavage of the
-lactam ring by hydrogenolysis of the N-C4 bond of 4-aryl-2-azetidinones was a facile reaction with 10% Pd/C as the catalyst; but no ring scission
occurred when Raney nickel catalyst was employed. Dehalogenation of aromatic compounds was also successful with ammonium formate and Pd/C catalyst.
Hydrogenolysis of phenylhydrazone of methyl benzoylformate gave the methyl ester of phenylglycine in excellent yield. The techniques described here
for microwave assisted hydrogenation are safe, rapid, and efficient and are suitable for research investigation as well as for undergraduate and high
school laboratory exercises.
chasing reference links can go on forever, but a microwave assisted review article via tetrahedron letters produced this interst.
Not that ammonium formate is hard to come by or procure
but what other possible hydrogen donors are possible to research? thanks
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roamingnome
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sorry to double post, but saving the OH group would be nice too...
I ask too much... i know...
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solo
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Reference Information
Microwave-Assisted Rapid and Simplified Hydrogenation
(imine reduction)
Bimal K. Banik, Khaled J. Barakat, Dilip R. Wagle, Maghar S. Manhas, and Ajay K. Bose
J. Org. Chem., 64 (16), 5746 -5753, 1999
Abstract:
Catalytic transfer hydrogenation has been conducted under microwave irradiation in open vessels using high-boiling solvents such as ethylene glycol
(bp 198 C) as the microwave energy transfer agent. Reduction of double bonds and hydrogenolysis of several functional groups were carried out safely
and rapidly (3-5 min) at about 110-130 C with 10% Pd/C as an efficient catalyst and ammonium formate as the hydrogen donor. Diverse types of -lactam
synthons were prepared by the reduction of ring substituents containing alkene and alkylidene groups or conjugated unsaturated esters. Cleavage of the
-lactam ring by hydrogenolysis of the N-C4 bond of 4-aryl-2-azetidinones was a facile reaction with 10% Pd/C as the catalyst; but no ring scission
occurred when Raney nickel catalyst was employed. Dehalogenation of aromatic compounds was also successful with ammonium formate and Pd/C catalyst.
Hydrogenolysis of phenylhydrazone of methyl benzoylformate gave the methyl ester of phenylglycine in excellent yield. The techniques described here
for microwave assisted hydrogenation are safe, rapid, and efficient and are suitable for research investigation as well as for undergraduate and high
school laboratory exercises.
[Edited on 22-12-2006 by solo]
Attachment: Microwave-Assisted Rapid and Simplified Hydrogenation.pdf (201kB)
This file has been downloaded 1987 times
It's better to die on your feet, than live on your knees....Emiliano Zapata.
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Hilski
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| Quote: | Originally posted by Organikum
Acetone can be used but it requirers the use of much more water as solvent to prevent the toxic effects of acetone and IPA onto the yeast. About twice
as much. And this makes the whole thing a bit unfavorable.
/ORG |
So, in your opinion, is it worth it to even try to add an additional hydrogen acceptor?
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Counter_Culture
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Al/Hg
Any comments for the following up-coming fictional event?
If not will go ahead and report results.
An Osmium/BrightStar style Al/Hg reductive amination of
l-pac where a 1.5 molar excess of methylamine is used.
Mixed is MeAm.Hcl (approx. 1mol) in dH2O.
Mixed is equimolar amount to MeAm.Hcl of NaOH in dH2O, cooled.
Mixed is MeOH, Al foil, HgCl2 in RBF.
Slowly poured is NaOH solution into MeAm solution, then added to RBF.
All at once is added crude l-pac (approx. 0.67mol).
Reflux, stirring (ice bath??) and let settle.
One wishes to avoid racemizing l-pac (high temp.) prior to imine formation/reduction.
Considering a sub zero deg. ice bath to control temp. Usure of effects on imine formation and reduction.
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roamingnome
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i personally dont mind discussing mercury amalgam issues, but i can see how it can get old for the elders in a jiffy....
by all means post your results. after all i think results is what this forum is all about unlike a post like the one im typeing at the moment.... in
my limited use.. i had better luck with methanol as the working fluid of the reaction...
but dude.... im encouraging the atainment and expirmentation of newer methods ......better methods
2.45 gigahertz dude 2.45 gigahertz
in other news: jon did you add a comment about zinc reduction? yes after reading a paper on the reduction of imine with 5 % NaOH in water
with zinc im thinking at the moment it is the most economical OTC way possible
another paper hinted at useing 95% ethanol which i hope will work and not change the reaction pathway becuase the indian group was useing ethanol as
the homogenous solvent for imine formation
in the first place......
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solo
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Reference Information
Organic Reaction in Water. Part 1. A Convenient Method for Reduction of lmines Using Zinc Powder
Takehito Tsuklnoki*, Yoshiharu Mitoma, Satoko Nagashima, Takatoshi Kawajf, Iwao Hashlmoto* and Masashi Tashiro Tohwa
Tetrahedron Letters 39 (1998) 8873-8876
Abstract:
Reduction of imines was performed with zinc powder in 5% aqNaOH solution without any organic solvents undea" mild conditions, and the eor~sponding
amines were obtained in good yields null
Attachment: Organic Reaction in Water. Part 1. A Convenient Method for Reduction of lmines Using Zinc Powder .pdf (206kB)
This file has been downloaded 3484 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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ahhhhh the most coveted.... tetrahedron letters....
thank you is not enough.....
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Counter_Culture
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Sounds promising.
5g zinc for 5 mmol substrate.
1 kg of zinc for 1 mol l-pac.
How to form stable imine in a suitable solution for zinc reduction? nh3 in alc. ?
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Hilski
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| Quote: | | How to form stable imine in a suitable solution for zinc reduction? nh3 in alc. ? |
If I understood the paper correctly, the NH2OH addition product (oxime) can also be used successfully in this reaction, with ~63% yields.
That is, if norephedrine is the desired end result.
[Edited on 29-12-2006 by Hilski]
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roamingnome
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From the electro reductive mechanisms ive have been able to embrace the oxime is first reduced to the imine and further along...
come to realize that amalgams are sorta like hot wired circuits, either way you need metals for redox. The lure of electrodes is nice, but a slurry
of Zinc will suffice...
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brewette
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Mexchem2006,
Has a microwave process with clay been considered for hydroamination of l-pac?
I notice a paper from Mumbai Uni outlining a wet microwave process with 50% conversion for each of the hydrogenation and amination reactions and
recovery of the unreacted l-pac. Easier than pressure hydrogenation.
Brewee
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jon
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what a find, you know the typical o-chem book would have you believe that slightly acidic conditions are needed for amino carbinols to eliminate H2O
to form the imine (this is the species reduced hypothetically). but this is not the species that undergoes reduction in the example you give using
zinc. I also see this in another paper where aminocarbinols are the intermediate in transition.
not everything goes like they say in textbookland.
The zinc reduction I was refering too is a CTH type reduction where zinc acts more like a catalyst and formates are the proton donors.
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Organikum
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| Quote: | Originally posted by Counter_Culture
Sounds promising.
5g zinc for 5 mmol substrate.
1 kg of zinc for 1 mol l-pac.
How to form stable imine in a suitable solution for zinc reduction? nh3 in alc. ? |
Anybody here got near
reality lately? One kilo zinc powder for one mole substrate yielding a product which cannot by normal means be distilled by steam? And this goes
unchallenged? You are kidding, thats just ridiculous if not pathetic. Did anybody even think of workup?
If I got my hands on some pure l-PAC (small question: how is this stabilised? If not then you´ll have PAC but no l-PAC) I´ll get my hands on some
suitable Pt catalyst and run this clean. But for all I can see this are just theoretical musings here, not touched by the dirty hands of actually
doing something. Hilsky is an exception - maybe.
And another question: Does anybody know this wanking moderator of drugs-forum.com (where I am banned) who pulled up the genious stunt to contact me by
mail posing as an iranian female chemist to extort some information on this process from me? Hey! Go and stuff yourself or learn iranian before trying
something like this. Some chemistry wouldnt hurt either, questions like "I don´t understand the role of pyruvate in the reaction" from a chemist
(with a "Dr." !) are not so very bright.
funny things happen....
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Organikum
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| Quote: | Originally posted by Hilski
| Quote: | Originally posted by Organikum
Acetone can be used but it requirers the use of much more water as solvent to prevent the toxic effects of acetone and IPA onto the yeast. About twice
as much. And this makes the whole thing a bit unfavorable.
/ORG |
So, in your opinion, is it worth it to even try to add an additional hydrogen acceptor? |
Yes. Pyruvate.
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jon
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so organikum you think the ZnII(OH) would form a gelatinous mess making extraction next to impossible?
what about the other zinc/acid reductions where ZnII(Cl) is converted to ZnII(OH) on basififcation? this is the same scenario. Acid base extraction
was touted to work in this case.
And I had a question on thinking of the scheme a little more I think you mentioned that L-PAC is unstable to bases, unstabe as in aldol condesations
with itself or just unstable stereochemically? also in the other thread they say nor-ephedrine+heat+base=tarry mess. (heat is like 100 centigrate)
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roamingnome
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I shout conspiracy
I really need to stand up in defense for
A) Tetrahedron Letters, and all the scientists who wrote the article
B) 2 Hydrogenolysis articles, and the scientists that wrote the articles.
C) Scientific musing
Lets go back to Dec 26, 2000 when Rhodium posted literature regarding Hydrogenolysis in IPA, well you where there Org and that’s all well and good
and sentimental, but then on 30-4-2006 CherrieBaby reposted it in a lack luster yet new thread on this forum. In 103 minutes you tell us not to waste
our time and money on it. Are you suggesting that all the professional scientists who authored a professional article are bunk and dumb?
Are you furthermore suggesting the authors of the tetrahedron article or also as equally dumb! Well I cant afford your fancy palladium “clean”
catalysts. I think it looks like a pretty clean approach considering that at that point your extracting ppaHCl out of freaking water with maybye some
zinc ions in it.
Finally people play video games where we shoot the bad guy and get swords and battle axes and potions to slay mythic creatures in a fantasy world. The
reason people do this is because killing people for real is immoral! And mythic creatures dont freaking exist!
Im sorry I don’t have time/ money/ equipment to perform experiments 24-7. I personally like this forum and im soooo sorry if im this or that or not
enough of something else.
Talking about science, in an edifying way, is just as good as actually doing it! That’s why it’s a forum of text …… so when I actually go to
do an experiment Im giving it that best possible approach. It fills that gaps when im not able to perform reactions.
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Organikum
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I am telling from experience that a lot of scientific articles are plain bullshit or at least misleading. Thats actually nothing new. Patents are even
worse.
It is quite obvious that a kilo zinc powder per mole substrate will give a petty mess.
Also you are not referencing it, I suppose that the hydrogenolysis article posted by Rhodium you refer to is the one where Ephedrine was reduced by
some fancy nickel catalyst in IPA and the authors claimed IPA being the hydrogen donor. Without finding any acetone in the post reaction mixture,
wonders over wonders.
This article was bullshit, it was nothing more then an advertisement for a new catalyst. Ipa was not the hydrogen donor - the fucking catalyst was so
preloaded with hydrogen that there was just no need for any hydrogen donor.
You are wisecrack without a clue.
| Quote: |
Talking about science, in an edifying way, is just as good as actually doing it!
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I disagree. I am also convinced that actually having sex is better then watching porn.
/ORG
[Edited on 3-1-2007 by Organikum]
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roamingnome
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I'm sure some mistake was made in posting what was originally here, because it was so offtopic and inflammatory that "moderators, please ban me now"
would have retained the spirit of the post while improving brevity greatly. I have edited this message to avoid confusion on the previous point.
If there was no mistake, please repost what was here before, or something like it, and the desired ban will soon be delivered.
[Edited on 1-4-2007 by Polverone]
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Ephoton
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This is in the wrong thread sorry but I did not want to start a new thread just to ask this question which relates to l-pac. how does one convert
l-pac or pac into P2P.
will the pinacol rearrangement do the trick as it does for diols or do you have to reduce
the carbonyl to an alcohol first. thanx for any who answer and sorry to push in like this.
e3500 console login: root
bash-2.05#
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roamingnome
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I dont want to be banned... i will pace in circles 12 times and 4 deep breaths before getting jumpy
I will "soon" run confirmitory analysis on said methodologys in libo, to insure freshness. and no ecoli or trans fats.
why oh why would you ever want P2P from pac. Unless you have a secrete use for it thats like taking 2 steps foward and 3 steps back. i didnt mean to
ryme there by the way...
lets just say for all the proper reasons a research lab needed the amphetamine or methylated analog. If you read the Hydrogenolysis articles one deals
with just that!
Assuming that they are valid methods then snipping off an OH group seems pretty much taken care off. That is relfuxing in IPA with raney nickel,
but read those articles and i want book report on your feelings and summer vaction by monday.
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roamingnome
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http://www.arkat-usa.org/home.aspx?VIEW=MANUSCRIPT&MSID=...
http://journals.iucr.org/a/issues/2005/a1/00/a33149/a33149.p...
As the day approaches, maybye ya’ll already figured this out, and have been doing it since 1983 who knows…
But ammonium acetate shall/can be used to form said imine in microwave assited (MA) reaction with l-pac
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Ephoton
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im a chromic fan  no raney here and wial I can get Pt im not aiming for that. I
would like a otc from pepper and this is the best I can find for the novice. so one would expect that you would have to do an amalgum first then do
the pinacol. cool.
oh by the way your a microwave nut i love it.
[Edited on 10-1-2007 by Ephoton]
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