Method for producing polyethylene glycol containing terminal carboxyl group and method for producing activated polyethylene glycol

摘要

According to the present invention, there is provided a method for producing polyethylene glycol containing a terminal carboxyl group, characterized in that it has steps 1 and 2. Process 1: A solution containing polyethylene glycol having a hydroxyl group, an inorganic base in an amount of 0.5 to 4 times by mass relative to the polyethylene glycol, an aprotic solvent, and water, the mass of the water being 5 to 20 meq relative to the inorganic base, and the solution A step of obtaining a polyethylene glycol ester by reacting a compound of the following formula (1) with the polyethylene glycol in a solution having a mass of the water of 2000 ppm or less. (X represents a leaving group, a represents an integer of 4 to 9 , and R 1 represents a hydrocarbon group having 1 to 4 carbon atoms.) Process 2: A step of hydrolyzing the polyethylene glycol ester to obtain a terminal carboxyl group-containing polyethylene glycol.