Patent ID: 7608663

Claim:
A method for preparing a water soluble and non-peptidic polymer functionalized with at least one propionic acid group, the method comprising: i) reacting a water soluble and non-peptidic polymer comprising at least one hydroxyl group with a tertiary alkyl acrylate in the presence of a catalyst comprising a quaternary ammonium salt to form a propionic acid ester of the polymer, wherein the polymer has a weight average molecular weight of at least about 10,000 Da; and ii) treating the propionic acid ester of the polymer with a strong acid to form a propionic acid-functionalized polymer; with the proviso that the water soluble and non-peptidic polymer functionalized with at least one propionic acid group is neither methoxy PEG propionic acid having a weight average molecular weight of about 20,000 Da, nor methoxy PEG propionic acid having a weight average molecular weight of about 30,000 Da.