Method for producing polyoxalkylene derivative

A method for producing a polyoxyalkylene derivative represented by the following formula (1), the method comprising successively performing the following steps (A), (B), and (C)

• wherein Z is a residue of a compound having 2 to 8 active hydrogen atoms;
• Polymer1 and Polymer2 each independently represent a polymer of an oxyalkylene group having 2 to 4 carbon atoms, Polymer1 and Polymer2 may have a side chain, and the polyoxyalkylene derivative represented by the formula (1) has an overall molecular weight of 1,000 to 160,000;
• R represents either a hydrocarbon group having 1 to 20 carbon atoms or a protected functional group;
• X represents an oxyamino group or an amino group;
• a and b each independently are 0≦≦a≦≦8, 1≦≦b≦≦8, and 2≦≦a+b≦≦8;
• and n is 1 or 0:
• step (A):
• a step in which a polyoxyalkylene derivative having hydroxyl group(s) represented by the following formula (2) is reacted with a phthalimide derivative in the presence of an azo reagent and a phosphine reagent,
• wherein Z, Polymer1, Polymer2, R, a, b, and n are the same as defined above;
• step (B):
• a step in which deprotection of the phthalimide group(s) of the compound obtained in the step (A) is performed using a deprotection reagent comprising an organic base having a primary amino group;
• step (C):
• a step in which impurities derived from the phthalimide derivative and the deprotection reagent are removed using step (C1) or (C2):
• step (C1):
• an adsorption step in which an adsorbent is used in an organic solvent;
• step (C2):
• an extraction step in which an organic solvent and an aqueous solution of an inorganic salt are used.