Hi everyone.
During some experiments, passing aniline through the glass reactor of a continuous-flow equipment went suddenly wrong, and the mixture solidified, presumably due to polymerization of aniline... we're not really sure.
Does anyone have experience with clogged glass reactors? Any suggestions?
Thanks in advance.
Depending on the material of construction (no Peek or Polystyrene) I would try soaking or sonicating the reactor in chloroform, or chloroform methanol 1:1. It might help to leave the reactor in the solution overnight.
Also you can try with an acidic solution. Polyaniline is doped in acidic media and it forms a dispersion in water.
The product proved resilient to both choloform and acidic treatment. According to the vendor of the reactor, sonication may lead to detachment of the chip at the glass-glass contact, and this would definitely kill the reactor. The problem resides in the diameter of the clogged channel... too small for anything to penetrate it.
Try forcing the chloroform through the reactor with a gastight syringe or soaking it in boiling chloroform overnight. Is this an Asia glass microreactor?
Yes, it is an Asia microreactor. I'll try boiling chloroform. Thanks a lot!
I am not sure but the plastic around the window for the reactor might be Peek which is not compatible with chloroform and the frame around that is anodized aluminum which is also not compatible with chloroform. I would check with Asia about the material compatibility of the outside of the microreactor. Try forcing chloroform through the reactor with a syringe.
Hi, Bruce Levison. Many thanks for your suggestions. I tried forcing chloroform, and different solvents, water, acid. It's a resilient, yellow gel or solid. We'll keep trying! We have thought of piranha solution... but it may be very aggresive and we are still not sure if we should give it a try.
Best regards.
Hi, Vladimir Dvoryanchikov:
I will try a water solution of sulfite. Many thanks for your suggestion.
Best regards.
Hello,
You should use Piraña solution, then acetone, then ethanol
Joshua
Hi, Joshua Britton.
Many thanks for your tip! I haven't tried it yet.
Have you tried this approach? It worries me piranha solution may be too aggressive...
Thanks again!
Hello,
The reactor is glass. This approach is used all the time to clean glass surfaces. It will just make the surface very clean, back to the original Si-OH bonds on the glass surface.
Joshua
I would be careful using acetone after Piranha solution. The formation of TATP is possible which is highly explosive.
See
http://cenblog.org/the-safety-zone/2015/01/piranha-solution-explosions/
Hi everyone.
Thanks for sharing your experiences and suggestions on how to clean the glass reactor. After months of trying, it is finally back to work.
What I did was: Pushing aqueous HCl with a syringe into the reactor. There was an air bubble keeping the acid from coming into contact with the obstructed zone. It took about two weeks for the acid to slowly diffuse towards the unwanted product and dissolve it. But it worked! Now its fine and ready to do some flow chemistry again.
Hope this info may be of help
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