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Author: Subject: Acid hydrolysis of sucralose workup... Stuck
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[*] posted on 6-11-2017 at 15:11
Acid hydrolysis of sucralose workup... Stuck

I'm stuck... after the acidic hydrolysis of sucralose you would get 4-chloro-4-deoxygalactose (4-CG) and 1,6-dichloro-1,6-dideoxyfructose (1,6-DCF)... so far so good, the problem is how the hell do you separate them both with conventional chemistry (that is, no chromatography columns, no ion exchange resins, no fancy chemical work up and for god's sake no fifty liquid-liquid extractions...)

I tried getting information on the property of both compounds but I found non... My first thought was that maybe you could try oxidizing the aldehyde to the carboxylic acid with mild oxidants but there is no information about how sensible the ketone is to oxidation... or if any of the alcohols would get also oxidized in the process to their ketones, so at the end I realized how big of a mess this process would be and moved on. Yet I think it’s worth a shot because of how easy the workup would be following this procedure:

DOI: 10.1111/jfpp.12742

Then since I was getting nowhere with the separation of these two I thought of not isolating them but first making them react into something way easier to separate, the thing is how or what to use for this.
Precipitation with bisulfate adduct is my best bet so far... after a while I gave up and just decided to try stuff instead of plane thinking so I will see how it goes.

Even though, what are your thoughts on this guys? any help will be greatly received… as I stated before, I am stuck so far with this...
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[*] posted on 7-11-2017 at 10:47

I giggled to myself about the wording, a sweet compound in the reaction, you're "stuck", har har... I know bad jokes. Mind, I'm not laughing at your troubles however.

I took a look at those molecules on PubChem, and I suspect, based on the placement of the functional groups that they will have a big enough difference in polarity or pH that they might be extracted from one another via their relative solubilities in a system.

I would try to create a saturated, hot alcohol solution of the mixture, then let it cool, and filter the things that crystallize out at room temperature and analyze them, try again after cooling in a fridge, etc.

And then if that didn't work I would attempt the same procedure using a non-polar solvent like ether or hexane.

I would try to use pure/anhydrous solvents because it would simplify things and probably provide better separation.

I would avoid trying this with water first, because water dissolves so many things.

Now on the subject of adducts, since one of the products is an aldehyde, and I know that saturated Sodium Metabisulfite solutions can form adducts with some aldehydes based on my experience with purifying benzaldehyde, and Sodium Metabisulfite is cheap and available, that sounds to me like a very viable option.

As for oxidation of the aldehyde to the carboxylic acid, again, same deal, this is a cheap reaction if you're using H2O2, and drugstore peroxide is low concentration, so probably less likely to be as destructive as say lab grade 35% H2O2. If you are unable to convert the aldehyde, you could try something with different kinetics like a percarbonate salt or a per-acid of some kind, the immediate one that comes to mind is peracetic acid. You could also go full bore overkill and make a piranha solution and try that, in very dilute form, maybe cold, to see if you can selectively oxidize by tweaking the kinetics of that solution.

Also how do these compounds react to heat? Would it be easy for you to try to separate them via Sublimation? Vacuum or atmospheric distillation?

I know that sucralose is cheap where I'm located, I might pick up a bag of ye olde non-sugar sweetener and attempt this myself. Which acid did you hydrolyze with?

Only two things are infinite, the universe and human stupidity, and I'm not sure about the former. - Albert Einstein

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