Patent ID: 8349969

Claim:
A method for preparing PEG aldehyde represented by Chemical Formula 1 by reacting a PEG derivative represented by Chemical Formula 4 with dimethyl sulfoxide and dicyclohexylcarbodiimide: OHC—(CH 2 ) m-1 —O—(CH 2 CH 2 O) n —(CH 2 ) m-1 —CHO [Chemical Formula 1] HO—(CH 2 ) k —O—(CH 2 CH 2 O) n —(CH 2 ) k —OH [Chemical Formula 4] wherein n represents an integer from 3 to 2000; and k represents an integer from 3 to 10; wherein the PEG derivative represented by Chemical Formula 4 is first prepared by a process comprising the steps of: reacting PEG represented by Chemical Formula 3 with cyanoalkene represented by Chemical Formula 5 to prepare cyanoalkyl-PEG represented by Chemical Formula 6; preparing PEG-carboxylic acid represented by Chemical Formula 7 from the cyanoalkyl-PEG represented by Chemical Formula 6; reacting the PEG-carboxylic acid represented by Chemical Formula 7 with alcohol represented by Chemical Formula 8 to prepare a PEG-ester compound represented by Chemical Formula 9; and reducing the PEG-ester compound represented by Chemical Formula 9 to prepare the PEG derivative represented by Chemical Formula 4: HO—(CH 2 CH 2 O) n —H [Chemical Formula 3] HO—(CH 2 ) k —O—(CH 2 CH 2 O) n —(CH 2 ) k —OH [Chemical Formula 4] NC—(CH 2 ) k-1 —O—(CH 2 CH 2 O) n —(CH 2 ) k-1 —CN [Chemical Formula 6] HOOC—(CH 2 ) k-1 —O—(CH 2 CH 2 O) n —(CH 2 ) k-1 —COOH [Chemical Formula 7] R 1 —OH [Chemical Formula 8] R 1 OOC—(CH 2 ) k-1 —O—(CH 2 CH 2 O) n —(CH 2 ) k-1 —COOR 1 [Chemical Formula 9] R 1 is selected from (C1-C7)alkyl or (C6-C20)ar(C1-C7)alkyl.