Preparation of monomethyl ethers of poly(ethylene glycol)s free of the poly(ethylene glycol)

In this report, poly(ethylene glycol) (PEG) was quantitatively removed from commercial monomethyl ethers of PEG (MPEG) by column chromatography on sil ica gel on a preparative scale. Most of commercial MPEG, with molecular wei ghts as high as 5000, and containing only up to 20% of PEG, were effectivel y purified by this technique. The content of PEG in MPEG obtained is compar able or even lower than that in samples of MPEG prepared by anionic polymer ization of ethylene oxide under strictly controlled conditions. An analytic al approach combining H-1 NMR and chromatography techniques indicates that the PEG content in the chromatographically purified MPEG samples is less th an 1%.