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Author: Subject: Ideas to make long-chain alditols
subskune
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[*] posted on 15-8-2019 at 11:26
Ideas to make long-chain alditols


Hey there,
I want to make some very long-chain alditols (sugar alcohols). Basically polymers.



The problem is: I have no idea how to start. The 1,2 Dihydroxyethylene does not exist in its -ene form. The route of how polyvinylalcohol is made does not work, since the double bond is locked between two substitutents.

Any ideas?




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Pumukli
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[*] posted on 16-8-2019 at 05:55


Aren't these sugar-like compounds made from formaldehyde polymerized with Ca(OH)2? Are those something different?
Anyway, formaldehyde polymerization works best with a moderately strong base, hence Ca(OH)2 is used afaik.
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Metacelsus
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[*] posted on 16-8-2019 at 10:44


I thought formaldehyde polymerization gave polyoxymethylene: https://en.wikipedia.org/wiki/Polyoxymethylene

Although the polyols do have the right empirical formula, I don't think they would be the major product under base-catalyzed polymerization.

Doing some more research, I see this might also take place if calcium is present: https://en.wikipedia.org/wiki/Formose_reaction

It could make some short oligomers but it would require a considerable amount of optimization to get long chains.




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Pumukli
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[*] posted on 16-8-2019 at 10:58


Yes, Metacelsus, you are right. Subskune explicitely wants "very long chain" polyols, this Butlerov reaction may not yield it, even after several days of condensations. :)
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subskune
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[*] posted on 17-8-2019 at 04:27


The wiki entry states that the resulting alcohols of the formose reaction are C2-6. I thought of something like 100+.

Onthe other hand formaldehyde is the monomer of the repeating group of this alditols. Maybe there is a fancy way of converting POM directly. Papers on this topic are quite scarce.





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Metacelsus
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[*] posted on 17-8-2019 at 04:42


The issue with aldose chains longer than C5 is that they can cyclize, which stops them from growing longer.

I bet it would be possible to develop a specialized catalyst for making long chains, but it certainly wouldn't be easy.

What are you planning to use these for? There may be substitutes.




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TGSpecialist1
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[*] posted on 17-8-2019 at 08:45


https://en.wikipedia.org/wiki/Vinylene_carbonate

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Metacelsus
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[*] posted on 17-8-2019 at 23:40


Good idea! That should definitely work.



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subskune
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[*] posted on 18-8-2019 at 01:19


Thank you a lot!!! Exactly what I was looking for:)



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TGSpecialist1
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[*] posted on 18-8-2019 at 07:06


Note that if you'll use organic peroxide as a polymerization catalyst then your final polymer will be terminated with aldehyde groups.
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