The general procedure for the synthesis of dibromopenta PEG from pentaethylene glycol disulfonate (CAS: 109789-39-1) is as follows: in Example 2, pentaethylene glycol disulfonate (3.94 g, 10 mmol) was dissolved with tetrabutylammonium bromide (13.3 g) in acetonitrile (50 mL). The reaction mixture was stirred for 16 h under the protection of nitrogen atmosphere. Upon completion of the reaction, the solvent was removed by distillation. Subsequently, liquid-liquid extraction was performed by adding ethyl acetate and water to the residue. The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated. Finally, the target product dibromopenta PEG (2.73 g, 75% yield) was purified by column chromatography. The structure of the product was confirmed by 1H-NMR (CDCl3): δ 3.49 (t, 4H), 3.69 (s, 12H), 3.84 (t, 4H).
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