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I am trying on doing tosylation of PEG using Tosyl Chloride with pyridine. Some articles mentioned about filtering fine particles (pyridinium salts?) after diluting with DCM. But they did it with some filter-aid like celite which I don't have access to.

On my first try, I didn't filter it and during washing (HCl, NaHCO3, brine), there seemed to be a pretty intense emulsion. I am wondering if it was caused by those particles I didn't filter.

I also tried to quench it with water instead of dcm then extract with DCM, the emulsion thing still occured.

Therefore, I would like to ask if there is any other methods of filtering those fine particles beside filter-aid. Would syringe filter work?

Thanks a lot

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  • $\begingroup$ Very likely the fine particles are causing your emulsion. Syringe filter worth trying. $\endgroup$ – Waylander Feb 6 '18 at 8:49
  • $\begingroup$ You can try with a pad of silica gel. It won't be a column. You go till no spot develop/is visible $\endgroup$ – Alchimista Feb 6 '18 at 9:31
  • $\begingroup$ Thank you! I will try both. @Alchimista regarding the silica pad, how do you prepare it? Is it by the same fashion the celite pad is prepared? $\endgroup$ – Karn Changsorn Feb 6 '18 at 10:51
  • $\begingroup$ Imagine to pack a column. You choose the largest column you have (in diameter! ) and you pack it with a minimal amount of silica. You can fix the silica even without slurry, just drop and press it and perhaps hold it with a cotton. Else you do it as with celite. Twice I used fltration through silica gel unplanned to recover products from accidental spill and sometimes to (with luck) removes trace impurity that prevented crystallisation from oily crudes. To say that after filtration you can washed/extract your eventually adsorbed product to minimize loss. But it depends on the scale and value. $\endgroup$ – Alchimista Feb 6 '18 at 11:44

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