The MPEG monophosphate ester: synthesis and characterization.

Methods of preparation of the phosphoric ester of monomethyl ether of poly(ethylene glycol) (MPEG-P) from MPEG (M n = 550 and 2000) and phosphoric acid (P), or its derivatives — pyrophosphoric acid (PY), polyphosphoric acid (PP) and POCl3– are described and compared. MPEG-P was isolated in a pure state (no detectable impurities) and characterized.