[magician4]

Hi there,

I want to prepare pTos-O-(C₂H₄-O-)₄- pTos , with by traditional approach can be done by reacting 1 eq. of PEG with 2 eq. pTosCl, 2 eq. pyridine in CHCl₃  at approx. 0-4°C , 3 h

as I am not esp. fond of using pyridine, I was wondering if stirring 1 eq. of PEG with 2 eq. pTosCl in THF , with a slurry of excess finepowdered dry CaCO₃ should do the same job.

What are your ideas / remarks / critique about this approach?

tnx for all your insights

regards

Ingo

[Babcock_Hall]

I have used triethylamine in reactions involving pentafluorobenzenesulfonyl chloride and trifluoroethylsulfonyl chloride.  I don't recall having used this base in a tosylation reaction, and I have no experience specifically with sulfonylester formation starting with PEGs.

[magician4]

thank you!

standard bases that should work, due to literature , would be NEt₃, Py, and 4-DMAP
( in ascending order ref. reaction speed, yield , if memory serves)

however, my main concern with an alternative approach is pTosCl being sufficiently stable in a THF/ CaCO₃  matrix, due to carbonate in heterogenic phase being around


regards

Ingo