Azido-PEG6-t-butyl acetate is a bifunctional polyethylene glycol (PEG) derivative containing an azide group (-N₃) and a t-butyl ester protecting group, with the molecular formula C₁₈H₃₅N₃O₈ and a molecular weight of approximately 421.48. Its structure consists of a six-unit PEG (PEG6) chain linking the azide group to the t-butyl ester moiety, combining hydrophilicity and reactivity. The production process involves coupling an azidating reagent with a PEG6 intermediate, followed by introducing the t-butyl ester protecting group on the carboxylic acid, requiring strict anhydrous conditions to prevent side reactions. This compound is widely used in PROTAC molecule synthesis (connecting E3 ligands with target protein ligands) and ADC drug development (as an irreversible linker conjugating antibodies with toxins). Its azide group supports click chemistry modification, while the t-butyl ester group can be deprotected under mild acidic conditions to enable functionalization extension.