Benzyl-PEG4-t-butyl acetate is an aromatic ester compound containing a tetraethylene glycol (PEG4) chain. Its structure consists of a benzoyl ester group (-COOCH₂C₆H₅), a tetraethylene glycol chain (-O-(CH₂CH₂O)₄-), and a t-butyl acetate terminal group (-COOtBu), with a molecular formula of C₂₁H₃₄O₇ and a molecular weight of approximately 410.5. The production is achieved through a two-step process: first, 2-bromoacetic acid t-butyl ester reacts with tetraethylene glycol under alkaline conditions via nucleophilic substitution to form an intermediate, which then undergoes esterification with benzoyl chloride. The final product is obtained after purification by silica gel column chromatography. Due to the biocompatibility of the PEG chain and the stability of the aromatic ester, this compound is widely used in drug delivery systems (e.g., liposome modification), bioconjugation reactions (e.g., azide precursors in click chemistry), and polymer material modification.