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Fmoc-NH-PEG4-acid contains an Fmoc-protected amine and a terminal carboxylic acid. The PEG spacer increases the aqueous solubility of the resulting compound.
F 4034 (OTTO) Fmoc-NH-(PEG)₃-COOH, ≥95% Cas 557756-85-1 - used as reagent in chemical research.