Sciencemadness Discussion Board

Nitrosamine risks in a sulfonation reaction?

NightHawkInLight - 22-1-2025 at 12:03

It must be 15 years since my last post on this forum, I'm glad to see it's still going strong!

I've been looking into the sulfonation reaction presented in this paper: https://doi.org/10.1016/j.carbpol.2010.10.038

The reaction uses sodium nitrite and bisulfite in solution to form the sulfonating compound N(SO3Na)3. This is done under highly acidic conditions contributed by the bisulfite, and then the solution is brought to about 11 pH prior to adding the polysaccharide for sulfonation.

Does this reaction seem risky for the formation of nitrosamines, especially if there happened to be unknown organic contamination in the reagents?

This book mentions that sulfites are amoung the best nitrous acid scavengers in the prevention of nitrosamines, which is reassuring since the sodium bisulfite is used in excess: https://www.sciencedirect.com/topics/chemistry/nitrous-acid

However, in saying so the book also mentions that sulfites and nitrites produce hydroxylamine disulfonate, which seems like it could be further reduced to an amines in solution... Another source confirms this, that hydroxylamine disulfonate may react further to form amine trisulfonic acid or amine disulfonate (https://www.osti.gov/biblio/6693469?utm_source=chatgpt.com pg.6)

Oddly that paper which seems pretty thorough in exploring the reaction possibilities between nitrites and sulfites makes no mention of nitrosamines.

Any thoughts? Thanks

[Edited on 23-1-2025 by NightHawkInLight]

[Edited on 23-1-2025 by NightHawkInLight]

bnull - 25-1-2025 at 12:47

I'm more interested in the N(SO3Na)3, so I'm leaving the nitrosamine issues for someone better informed.

Quote: Originally posted by NightHawkInLight  
Any thoughts?

Well, this is the first time I see someone using nitrilosulfonate as a sulfonating agent. If it is indeed a sulfonating agent is a good question.

Some observations:
  1. potassium nitrilosulfonate is much less soluble in water than the sodium salt, making it quite easy to isolate and purify;
  2. Brauer (Handbook of Preparative Inorganic Chemistry, p. 506; see attachment or the book in the Library) insists that the solution must be alkaline at all times, otherwise disulfonate is formed;
  3. nitrilosulfonate decomposes to imidosulfonate or disulfonate in acid solution, which means that "highly acidic conditions" are not the best for its preparation;
  4. the reaction was performed without previous isolation of the compound, which means that there is more to the sulfonation than it seems at first.


Since Fan et al. didn't try to isolate the substance (why?) to make sure the sulfonation was due to nitrilosulfonate rather than, say, imidosulfonate or disulfonate, the best I can say is that the mixture is a sulfonating solution.

Another issue I see is that there are very few papers about this sulfonation in particularNote and most of them have at least one author (Lihong Fan) in common, which, given the amount of paper mills and how academic career advancement used to work in China, makes me more suspicious than usual.

You may want to isolate the potassium salt to see if it works. If yes, it is an unusual sulfonating agent; if not, the solution is the thing.


Note: I concede that my research was made pretty late at night (3 a.m.) thanks to the forgetful bastard next door whose exterior white LED lights shone on the white wall of my bedroom. I may have made some mistakes here but, well, I apologize in advance and life goes on.

Attachment: brauer_nitrilo_stuff.pdf (77kB)
This file has been downloaded 20 times

Edit: Writer's nitpicking.

[Edited on 26-1-2025 by bnull]

NightHawkInLight - 29-1-2025 at 10:46

Thanks for the reply. The N(SO3Na)3 compound is an interesting one, and seemingly novel to this group of papers. More frequently the sulfonating agent identified in similar solutions is amine trisufonic acid. See this patent: https://patents.google.com/patent/US2967178A/en and this image of reactions between HSO2 and HSO3:
https://i.imgur.com/l5t0FTX.jpeg (image is from this paper about the reaction kinetics: https://www.osti.gov/biblio/6693469?utm_source=chatgpt.com)

edit: I tried embedding the image but it was BIG. So back to a link.

The N(SO3Na)3 might be a red herring, or a particular twist on how the reaction plays out when Na ions are introduced. Either way I have confirmed now that the solution works for sulfonation. I still have some question about toxicity of side reactions, but others have given some reassurance that nitrosamines in particular are not likely with a high excess of bisulfite. I've been incinerating the leftover solvent in any case.

[Edited on 29-1-2025 by NightHawkInLight]