One preferred method includes reacting a polyalkylene oxide such as polyethylene glycol containing a terminal tosylate with a protected amine salt to form...http://www.google.com/patents/US7601798?utm_source=gb-gplus-sharePatent US7601798 - A pure polyetheramine for biological conjugugation formed by reacting a tolsylated polyoxyethylene glycol with a potassium salt of di(tertiary-butyl oxycarbony