Hydroxy-PEG-Methyl ester

Hydroxy-PEG-propionic acid methyl ester is a heterobifunctional PEG derivative featuring a hydroxyl group and a protected methyl ester, primarily used as an intermediate in multi-step syntheses where the ester requires subsequent hydrolysis to a carboxylic acid for conjugation. Its key advantages include orthogonal reactivity for sequential modifications, tunable spacer length (n), and protection of the carboxyl group during synthetic steps, though deprotection is necessary for final functionalization.