Sciencemadness Discussion Board - Functionalization of silica gel without silanes, solid supported TEMPO catalysts?


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Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Functionalization of silica gel without silanes, solid supported TEMPO catalysts?

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Klute

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posted on 8-6-2008 at 19:46

This is EXCELLENT! Much simplier than nitration, reduction, and subsequent reactions to extend the chain!

On the other hand, there seems to be a very small amount of functionalization takinbg place, 60pmol/g is ridiculously weak. But using expansed PS instead of rigid films, the surface could be largely extended and thus more functionalization could occur...

What is excellent with the two types of fucntions (-COOH and -OH) is that both cna be used, once activated, to couple with 4-hydroxy-TEMPO!

Using DCC/DMAP, the -COOH can be esterificated with 4-hydroxy-TEMPO, and the tosylates of the -OH can be used to alkylate the same TEMPO derivative!
I think both reactions should be done steps wise though, there might be too much interference between all the reagents.
Or maybe simply reacting the functionalized PS with thionyl chloride to form the acyl chlorides and the alkyl chlorides? The latter might be less efficent at alkyalting 4-hydroxy-TEMPO though.

One problem from such direct grafting would be the acces to the radicals: they might be a bit too close the polymer chain. Extending the latreral chaisn might be beneficial.

With the nitrated PS, I was thinking of reducing it to the PS-NH2, and reacting that with either activated adipic acid, or 6-aminohexanoic acid. The left oevr function (carboxylic acid or priamry amine) can then be attached to TEMPO derivatives (respectively esterification with 4-hydroxy-TEMPO and reductive amination with 4-oxo-TEMPO).

Maybe something similar can be done here: reacting the activated PS-COOH with 6-aminohexanoic acid, then the PS-OH with adipic acid, in two steps.
The two kind of chains can then be esterified with 4-hydroxy-TEMPO!

This really looks promising! Good find Alice!

\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"

-Alice Parr

LSD25

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posted on 8-6-2008 at 22:45

Here is something else, PS/PMMA were copolymerised and then sulfonated with SO3(g). The authors claim saturation of SO3 at the surface of the co-polymer, but the internal linked aromatic rings were not sulfonated. Applying that to here, treatment of the partially sulfonated PS from the wet-sulfonation with SO3 generated (ala Len1/GarageChemist) by some route, should result in a decent resin - the solubility of the same would be interesting.

Attachment: SulfonationSO3PSMMA.pdf (334kB)
This file has been downloaded 944 times

Whhhoooppps, that sure didn't work