Method for producing polyalkylene glycol derivative having amino group at end, with narrow molecular weight distribution

A method for producing a narrow molecular weight distribution polyethylene glycol derivative having an amino group at an end represented by a general formula (1) comprising the steps of:

• CH3O(CH2CH2O)nCH2CH2CH2NH2 (1)
• wherein n represents an integer of 1 to 450;
• 1) a step of reacting a compound represented by the general formula (2) with an alkali metal compound selected from M, M+H−, and RO−M+ (wherein M represents sodium (Na) or potassium (K), and R represents a monovalent alkyl group having 1 to 6 carbon atoms) to obtain a compound represented by a general formula (3):
• CH3O(CH2CH2O)kH (2)
• wherein k represents an integer of 2 to 5;
• CH3O(CH2CH2O)k-1CH2CH2O−M+ (3)
• wherein k is the same as defined in the general formula (2);
• and
• M is the same as defined for the alkali metal compound;
• 2) a step of dissolving a compound represented by the general formula (3) in tetrahydrofuran and then reacting with ethylene oxide to obtain a compound represented by the general formula (4):
• CH3O(CH2CH2O)n-1CH2CH2O−M+ (4)
• wherein n is the same as defined in the general formula (1);
• 3) a step of reacting the compound represented by the general formula (4) with acrylonitrile without further step of purifying the compound represented by the general formula (4) and then with an acid compound to obtain a compound represented by the general formula (5);
• and
• CH3O(CH2CH2O)nCH2CH2CN (5)
• 4) a step of reducing a compound represented by the general formula (5) to obtain a compound represented by the general formula (1).