Method of preparing carboxylic acid functionalized polymers

Abstract From the Canadian patent

Methods for preparing water soluble, non-peptidic polymers carrying carboxyl functional groups, particularly carboxylic acid functionalized poly(ethylene glycol) (PEG) polymers, are disclosed, as are the products of these methods. In general, an ester reagent R(C=O)OR' where R' is a tertiary group and R , comprises a functional group X is reacted with a water soluble, non-peptidic polymer POLY-Y, where Y is a functional group which reacts with X to form a covalent bond, to form a tertiary ester of the polymer which is then treated , with a strong base in aqueous solution to form a carboxylate salt of the , polymer. Typically this carboxylate salt is then treated with an inorganic acid …