I am using chlorosulfonic acid in chloroform (inert, 2 hr, RT) to para-sulfonate benzyl groups on a dibenzyl ether. The work up is extraction with water. The reaction, however, does not seem to work. Are there other reaction conditions and/or work up to try for aromatic sulfonation reaction?
I have tried an alternative, stirring with sulfuric acid for a few days, however, I cannot obtain pure product without large amounts of inorganic salts.
Try performing the reaction at elevated temp, even reflux. The reaction generates HCl so higher temps might reduce the amount of HCl in solution, pushing the equilibrium to product. Use at least 2.5-4 moles of chlorosulfonic acid for each substituent you want to add. Also could try adding various lithium, sodium, potassium or ammonium salts. See this patent:
https://patents.google.com/patent/CA1205491A/en
You could also try fuming sulfuric acid with or without SO3-pyridine complex.
Dillon
I think you are using the right reaction condition Chlorosulfonic acid in methylene chloride and you should follow the reaction with tlc. After the reaction is over evaporate the solvent and purify your products by silica gel flash chromatography (10-15% MeOH in CH2Cl2). Remember that you may have isomeric mixture [2- and 4-].
Good luck
Thanks for your reply Adel Amer . I can't seem to get any movement of the spot with TLC- I tried the solvent system you suggested, as well as combinations of ethyl acetate, hexanes, and ether. Any other suggestions?
Thank you again.
Dillon
Thanks for giving me the opportunity to help you. It is strange to me that most of the sulfonated species are Chinese patents (enclosed). Searching more I was able to get you a Russian paper for the preparation of sulfonated benzyl ether! They synthesized it from the bromo analogue! (enclosed)
Good luck
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