Hi. I have cellulose derivatives that are insoluble in acidic aqueous media. I want to hydrolyse them to monomers to analyse the sugar composition/substitution degree with MS.
I have been thinking about the TFA method but also using H2SO4 or HCl. What do you think? Advantages/disadvantages? Concentrations?
Thankful for all ideas :-)
-Ola
I don't undersatand, do you need hydrolyse cellulose but don't know how?? I use the procedures of the NREL. This is the metodology for analyses of the cellulose:
Yep. Thanks. But my problem here is that I have a cellulose ether (either benzyl cellulose or pentyl cellulose, not a natural biolmass sample) that I want to measure the non-, mono-, di-, and tripple- substituted monomers of. To do this I need to hydrolyse (with an acid) the polymer into monomers. I have read that Triflouro acetic acid (FTA) is too weak to be used as a diluted acid for cellulose, but I suspect that concentrated TFA might be used. HCl or H2SO4 (as in your example) are good acids to hydrolyse cellulose but might degrade some of the sugars (according to much literature) and are therefore not my first choice. Also, I strongly suspect that the mineral acids might be harmful for the ethers introduced in the synthesis.
I wanted to know whether you out there have any idea of what acid would be suitable, and in what concentration (?) I’ve also asked around here on my department, but nobody seems to be able to give a straight answer ;-)
H2SO4 72% is not diluite, for me. I Think you can use it. Look the procedure which I put for you before. More specifically I don't Know.
I would start with 0.25M HCl and reach up to 3.5M to see if the hydrolytic efficiency increases. Start the experimentation at 25oC and if not working I would recommend you an increase of up to 50oC. Personally I believe that even a low molarity at 25oC would do the work for you.
I will try your method Evangelos, and possibly also your Carlos. Thanks.
In the TAPPI method T 236, kappa number determination, all the cellulose is hydrolysed to enable to quanytify the lignin. Hence, as written there 100 ml of 4N H2SO4 in about a litre aqueous solution containing up to 5 grams of your disintegrated sample (in a mechanical disintegrator) will hysrolyse it.
Yepp Ron, but there is a significant risk of destroying the sugars (and the ethers connected with the sugars) if I do so, so I'd rather take it easy :-)
Hi Ola. You can take it easy if you have a pressure vessel that can go to 170 deg C. 0.5% of SO2 bubbled into each litre of the solution containing no mote than 100g of your mechanically disintegrated solution can be tried. If you do not have SO2, one can buy sulpurus acid off the shelf and dose similarly.
The solution to this problem seems to be hydrolysis in pure TFA (Tri Fluoro Acetic Acid) which is gradually diluted. The TFA dissolved the cellulose ether (48h). This solution was then recycle-boiled and in 10 min intervals the TFA concentration was decreased with water to 90, 80, 75, 67, 55, 47, 39 and finally 30 % (v/v). Efter 20 minutes of recycle boiling at 30% the heat was turned off.
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