H-1-NMR INVESTIGATION OF QUANTITATIVE FUNCTIONALIZATION OF POLY(ETHYLENE GLYCOL)S

Poly( ethylene glycol)s, with different molecular weights (4,000-20,00 0) and a monomethoxy-substituted poly(ethylene glycol)(molecular weigh t 5,000) have been quantitatively end group functionalized with bromo and amino groups. The bromination was carried out with thionyl bromide in toluene. H-1-NMR was used for the determination of the degree of s ubstitution by monitoring the characteristic signals for the - CH2Br p rotons in relation to the signals from the remaining hydroxyl groups. Under the conditions used, qualitative substitution was obtained after repeating the bromination reaction. The results were in agreement wit h elemental analysis. The bromo end group could be quantitatively conv erted into amino groups by reaction in absolute ethanol with excess of ammonia or ethylenediamine. Also in this case, H-1-NMR was used to de termine the quantitative substitution by the characteristic signals fo r the aminomethyl protons and the simultaneous disappearance of the br omomethyl proton signals. (C) 1994 John Wiley and Sons, Inc.