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Author: Subject: Workup of Baker's Yeast Mediated Reactions
Medyc
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[*] posted on 4-2-2020 at 12:05
Workup of Baker's Yeast Mediated Reactions


Hi all, I've been doing work in the area of chiral starting materials in organic synthesis, specifically the BY reduction product of ethyl levulinate. After the fermentation, the typical procedure is: filter, extract, dry, filter, evaporate.
During the extraction a nasty emulsion tends to form, resulting in the need to break it with lots of MgSO4, and lots of washing upon filtering.
Does anyone have experience with these BY reaction, and have you ran into this problem ?

Thanks.

[Edited on 4-2-2020 by Medyc]
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Johnny Windchimes
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[*] posted on 4-2-2020 at 12:31


I'm not sure if this relates specifically to your case, but I've had lots of "fun" playing around with the yeast-based L-PAC benzaldehyde synthesis, and no matter how well I filtered out the yeast, no matter what I used for extraction (ether, toluene....), I could never avoid a nearly unfix-able emulsion during the workup. I tried using NaCl to try and break it, which worked terribly.

Can I ask what scale you are on and how you filtered your yeast? I was at the 30 gallon scale and had to engineer a gravity tube out of 5" PVC and using sand as a filter. Again, worked terribly....
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karlos³
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[*] posted on 4-2-2020 at 14:22


Oh thats my field of interest!
You need to suction filter through celite to break these nasty emulsions, this is the best method of them all.
But my suggestion is, as I found this from experience, that you are better off if you just form alginate pearls of the yeast instead, this makes the workup sooo much easier.
I make L-PAC using these alginate beads and it works very, very well.
No emulsions ever.

Quote: Originally posted by Johnny Windchimes  
I'm not sure if this relates specifically to your case, but I've had lots of "fun" playing around with the yeast-based L-PAC benzaldehyde synthesis, and no matter how well I filtered out the yeast, no matter what I used for extraction (ether, toluene....), I could never avoid a nearly unfix-able emulsion

Really sounds like you're a beginner working with yeast.

[Edited on 4-2-2020 by karlos³]
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Johnny Windchimes
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[*] posted on 4-2-2020 at 14:49


Quote: Originally posted by karlos³  

Really sounds like you're a beginner working with yeast.

[Edited on 4-2-2020 by karlos³]



Really sounds like you are correct!:)
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phlogiston
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[*] posted on 4-2-2020 at 15:20


I know nothing about these reactions but worked with yeast a lot in a biochemistry lab. We always used centrifugation to separate yeast from the medium. Simple and effective (if you have a centrifuge)



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Medyc
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[*] posted on 5-2-2020 at 05:12


Quote: Originally posted by karlos³  
Oh thats my field of interest!
You need to suction filter through celite to break these nasty emulsions, this is the best method of them all.
But my suggestion is, as I found this from experience, that you are better off if you just form alginate pearls of the yeast instead, this makes the workup sooo much easier.
I make L-PAC using these alginate beads and it works very, very well.
No emulsions ever.

Quote: Originally posted by Johnny Windchimes  
I'm not sure if this relates specifically to your case, but I've had lots of "fun" playing around with the yeast-based L-PAC benzaldehyde synthesis, and no matter how well I filtered out the yeast, no matter what I used for extraction (ether, toluene....), I could never avoid a nearly unfix-able emulsion

Really sounds like you're a beginner working with yeast.

[Edited on 4-2-2020 by karlos³]


i do filter through celite, to separate yeast and supernatant, are you meaning filtering the extraction (organic+yeast-supernatant) ?
Also the scale is ~1L, 3ml levulinate, with 100g of yeast.

[Edited on 5-2-2020 by Medyc]
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karlos³
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[*] posted on 5-2-2020 at 05:47


Both, first the reaction without organics, then the supernatant with the solvent in case emulsions will form.
I would really recommend to you to use alginate beads of the yeast, this makes working with them so much easier.
Or alternatively, to run the reaction in an organic solvent with dry yeast activated with a tiny bit of water, this also makes for an easier workup.
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Medyc
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[*] posted on 5-2-2020 at 06:29


Quote: Originally posted by karlos³  
Both, first the reaction without organics, then the supernatant with the solvent in case emulsions will form.
I would really recommend to you to use alginate beads of the yeast, this makes working with them so much easier.
Or alternatively, to run the reaction in an organic solvent with dry yeast activated with a tiny bit of water, this also makes for an easier workup.


Any procedure available for the preparation of the alginate beads that you have experience with ?
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karlos³
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[*] posted on 5-2-2020 at 07:55


I do it like this, starting from fresh yeast:
I put the blocks of yeast out of their packing and let them dry for a few hours, so they are easier to crumble finely.
Then I suspense them in a 4% sodium alginate solution, it is important that all is finely suspended without any bigger pieces, those will clog the funnel.
I drip this into a well stirred 4% CaCl2 solution and after everything is added, leave them for 2h to harden.
Then they can filtered out with a kitchen sieve and washed with water, and they are ready to use.
Maybe 100ml alginate solution for 50g of fresh yeast, and around 300ml of CaCl2 solution for this amount, but more is better as you need to stir the calcium chloride solution and this becomes harder will all the yeast balls swimming in it.
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