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Author: Subject: Salting Out
aga
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[*] posted on 8-2-2018 at 11:05
Salting Out


A while back when NurdRage was having difficulty with his pyrimethamine Epic synthesis i stumbled across the compound vicine which has a similar N-substituted pyridine ring structure.


Pyrimethamine.png - 3kB
Pyrimethamine

vicine.png - 3kB
Vicine

The discussion was about extracting it from fava beans, lopping off the glycoside thingy and whacking on a chlorotoluene unit before shoving a bent stick where the other O is.

My part was 'just' to find a way to suck vicine from the beans, with all the complex OC Nerdy's problem.

After some research it turns out that much work has been done on vicine & fava beans because it's aglycone divicine has been found to be the cause of the disease 'favism' which affects some people if they eat those beans.

This paper is really good for getting vicine & convicine out of fava beans :-

Attachment: marquardt1983.pdf (2MB)
This file has been downloaded 73 times

Unfortunately the two stumbling blocks are an 'air classifier' which they use to separate the protein, fat & starch to create a protein concentrate. Not got one.

The second is the use of a centrifuge producing up to 20k G. Not got one of those either.

Today i found a paper advocating the great benefits of 'salting out' in OC workups :-

https://pubs.acs.org/doi/full/10.1021/acs.oprd.7b00197

So, in amateur fashion i've de-hulled and mashed up some beans, added enough acetone/water/NaOH to match proportions as used in the paper, shoved it in a cafetiere and used the plunger to remove most of the solids, added a pile of Na2SO4 then filtered a lot and adjusted the pH to about 7 to see if anything happens.

One of several previous attempts achieved some crystals, although i have no idea what they were, nor any way of really knowing.

Now it appears that the paper recommends sodium sulphate, however my question is: how do you predict if your desired compound will get salted-out, or salted-in ?

If any passing genius could answer this, i'd be grateful.




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aga
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[*] posted on 8-2-2018 at 12:05


Anyone ?

https://www.youtube.com/watch?v=3ugSWeOntYE




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JJay
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[*] posted on 8-2-2018 at 12:22


The answer isn't as simple as some people think it is :D But people sometimes look at polarity of the desired compound and the ionic strength of the solution after the salt is added. I think ammonium acetate is a common choice for amino acids. This isn't an amino acid, but I'd probably try that.

[Edited on 8-2-2018 by JJay]




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aga
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[*] posted on 8-2-2018 at 12:39


Cheers JJay.

Part of my problem is not knowing how to work out if vicine is polar or non-polar.

Is there some way to know that just by the molecule's structure ?

[Edited on 8-2-2018 by aga]




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[*] posted on 8-2-2018 at 12:50


I can tell by looking that vicine is polar as heck. All those hydroxyl groups and the amines are hydrogen bond donors, and the ketone and ether groups hydrogen bond acceptors.
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aga
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[*] posted on 8-2-2018 at 12:59


Whoah hoss !

Can you please point out to an OC noob what the hydroxyl and amine groups are.

I guess 'hydrox' means the HO bits and 'amine' means the NH bits.

Is that right ?

Which bit is a ketone ?




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[*] posted on 8-2-2018 at 13:57


You are correct. Hydroxyl is -OH and amine is N with one to three carbons singly bound, with the difference made up by H. In this case, I meant the primary amines (N with one carbon bound, -NH2) and the secondary anime (N with two carbons bound, -NH-). A ketone is O doubly bound to carbon, =O.
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[*] posted on 8-2-2018 at 14:17


That's really clear and very useful.

Thanks.




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