Sciencemadness Discussion Board

(Di/tri-Methyl) ammonium-functionalized celluose for transesterfication and Ion exchange membranes?

imidazole - 7-3-2025 at 09:04

I thought about making an anion exchange membrane a while back, thinking about trying to do some electrolysis stuff with it that I don't think is as worthwhile now, but this part of the idea stuck around in my head. I'm not sure if it's as useful now, but I figured I'd run the concept by others for constructive criticism. Please note this is the first time I've tried to write up a synthesis of any kind on the forum, and be patient if It's a little wordy.

Possible Use case:
The basic idea was to make a polymeric cation for making acids, but I also thought about using it for stuff like methylating stuff with Dimethyl Carbonate, which is somewhat accessible near me, and it probably could work as a usable base for something water sensitive?

Possible way to make it:
Cellulose is apparently soluble in DMF, so maybe it could be used as a solvent for this reaction, if needed.
The basic idea was to reflux Toluene Sulfonic acid with thinly cut and stretched cotton in some hydrocarbon solvent, maybe Toluene or mineral oil, to add toslylate groups to the cellulose OH groups (drying agent to drive forward?). From there I would extract the product from the excess acid using more solvent and filtration.

Using this tosylate ester, I would form amide groups with aq. ammonia to make an aminocellulose, followed up with the Eschweiler–Clarke reaction using formaldehyde to get the final product of a dimethylamine functionalized cellulose. For any unsubstituted OH groups, there might be an additional reaction crosslink some of the cellulose, but I think that might actually be more useful for the purpose.

Finally, alkylating it with methanol under acidic conditions to replace any remaining OH with O-CH3 to better protect it, and also quaternizing the amines to create the final product.

any thoughts?

bnull - 7-3-2025 at 19:17

Quote:
any thoughts?

It won't work, at least not in the way described above.

If I'm not mistaken, DMF dissolves cellulose by changing the structure of the latter; this may interfere with whatever reactions you intend to perform on the polymer.

Search "tosylated cellulose". There are several studies about it and many preparations (cellulose and tosyl chloride, for example). Refluxing cellulose with tosylic acid (strong acid) will result in hydrolysis (it is one way to make glucose) and a very low yield if any.

I don't think you'll make an amide by mixing tosylated cellulose and ammonia. It looks pretty much like an alkaline hydrolysis whose products are a somewhat-less-tosylated cellulose and ammonium tosylate.

Since you're interested in aminocellulose, read this: J. F. Haskins, A. H. Weinstein, Aminocellulose Derivatives, J. Org. Chem. 1954, 19, 1, 67–69. They followed the preparation of tosylated cellulose given by F. B. Cramer and C. B. Purves in The Unesterified Primary Hydroxyls in Acetone Soluble Cellulose Acetate, J. Am. Chem. Soc. 1939, 61, 12, 3458–3462. I suspect you can skip Eschweiler-Clarke by using a dialkylamine.

If at the end of the day your product will be effectively an anion exchange membrane, I have no idea. There are so many things that can go awry (my reasoning is one of them).

Edit: More stuff on cellulose membranes that may give you more ideas: Z. İmir, Cellulose Membranes via Alkaline Hydrolysis of Cellullose Acetate Membranes and Their Application in Organic Solvents, https://open.metu.edu.tr/handle/11511/43915

[Edited on 8-3-2025 by bnull]

imidazole - 10-3-2025 at 04:54

very nice resources, though that's not quite the answer I expected.

whoops, I meant dimethylacetamide, with LiCl it makes a molecular dispersion.
https://www.sciencedirect.com/science/article/abs/pii/003238...


In the case of the first step, I was worried about degradation more than hydrolysis, would drying agents and an aprotic solvent not drive esterfication forward without tosyl chloride?

As for the second two, I think you're right, sn2 isn't favorable in water, and Eschweiler-Clarke was more of a practical thing for me as I don't have dimethylamine

bnull - 10-3-2025 at 06:40

Quote: Originally posted by imidazole  
very nice resources, though that's not quite the answer I expected.

It rarely is. :D

Quote: Originally posted by imidazole  
In the case of the first step, I was worried about degradation more than hydrolysis, would drying agents and an aprotic solvent not drive esterfication forward without tosyl chloride?

The examples I have seen used the chloride. There was a procedure to produce cellulose oxalate (for filtration or something) that used molten (110 °C?) oxalic acid dihydrate and cellulose, no solvent or drying agent involved, with good yield. Perhaps the same works with molten tosylic acid (I'd bet on the anhydrous form). Do you have any means to verify the product?

imidazole - 10-3-2025 at 08:40

Hmm, no. I can't really think of a way I could feasibly test for any specific type of amine... I could freebase it and wash hard with deionized water, then see if it can change ph... I can't think of anything that wouldn't give results with possible unreacted parts of the cellulose.
Quote: Originally posted by bnull  

The examples I have seen used the chloride. There was a procedure to produce cellulose oxalate (for filtration or something) that used molten (110 °C?) oxalic acid dihydrate and cellulose, no solvent or drying agent involved, with good yield. Perhaps the same works with molten tosylic acid (I'd bet on the anhydrous form). Do you have any means to verify the product?