1. Preparation of methoxy polyethylene glycol amine 2000
2g of monomethoxy polyethylene glycol azide 2000 was dissolved in 20mL of dry tetrahydrofuran, followed by the addition of 10% palladium carbon 0.2g, the air in the reaction flask was replaced with hydrogen, and the reaction was complete at 25C for 24 hours. Filtering to remove the palladium carbon, evaporate the solvent under reduced pressure, anhydrous ether pulping for purification, yielding 1.8 g of product in 90.14% yield.
2. Preparation of methoxy polyethylene glycol azide 1000
Under the protection of nitrogen, 1.0g of monomethoxypolyethylene glycol 1000, 0.53g of triphenylphosphine, 0.56g of diphenyl azidophosphate were dissolved in 10mL of dry dichloromethane, and the reaction flask was placed in a low-temperature environment at 0C with stirring for a certain period of time to wait for the temperature inside the reaction flask to be lower than 5C, and then 0.4g of diisopropyl azodicarboxylate was added slowly by dropwise addition, and the temperature of the reaction flask was kept at 15C or lower during the dropwise addition. The temperature was kept below 15 during the addition. After the addition, the reaction system gradually changed from turbid to clear, and the color changed from light yellow to golden yellow. After 3 hours of reaction, the reaction was complete, and the volume was evaporated under reduced pressure to obtain a yellow oil, which was purified by pulping with anhydrous ether to obtain a product of 0.86g with a yield of 83.25%.
