Go for vacuum drying.

Hello Nusrat,

many thanks for sharing this very interesting technical question with the RG community. PEG6000-Sulfonic acid (PEG-SO3H) has been reported in the literature to be a "gummy solid". Thus you cannot expect a nice crystalline solid alway. What you can do is triturate your viscous liquid product with diethyl ether. Just add diethyl ether to your product and stir the mixture vigorously with a glass rod. This will result in a more or less solid precipitate. Then wash again with diethyl ethrer and dry the residue under vacuum.

Good luck and best wishes, Frank Edelmann

Rohit Thirumdas sir,

I have dried this product at vacuum rotary evaporator but found viscous liquid as final product.

what temperature and pressure is needed to dry this?

Hi again, Nusrat,

I suggest that you should also try the very simple precipitation method with diethyl ether. I'm pretty sure that this way you will get much faster a solid material than by simple drying under vacuum. My guess is that when you heat your material under vacuum it will become more viscous and sticky, but not solid. The purification of PEG-OSO3H by precipitation with diethyl ether is described in the following very useful article:

Sulfuric acid-modified PEG-6000 (PEG-OSO3H): an efficient, bio-degradable and reusable polymeric catalyst for the solvent-free synthesis of poly-substituted quinolines under microwave irradiation

Article ChemInform Abstract: Sulfuric Acid-Modified PEG-6000 (PEG-OS...

Fortunately this paper has been posted by the authors as public full text. Thus you can freely download it as pdf file.

Good luck with your work!

Frank T. Edelmann

Thank you sir

Hi Dr Nusrat Sahiba . I hope the following link might help: https://pubs.rsc.org/en/content/articlelanding/2011/gc/c0gc00953a

Also, I hope the following link could help: https://en.m.wikipedia.org/wiki/Polyethylene_glycol