Benzyloxy carbonyl-PEG-acid is a compound that belongs to the family of polyethylene glycol (PEG) derivatives. PEG is a versatile polymer that has been widely used in various fields, including pharmaceutical research and development. Benzyloxy carbonyl-PEG-acid has a functional group that contains both a carbonyl group and a benzyloxy group, making it useful in drug delivery systems. The carbonyl group can form covalent bonds with amine groups on drugs, while the benzyloxy group can be used to control the hydrophobicity of the compound. This allows for targeted drug delivery and increased solubility of poorly soluble drugs. Benzyloxy carbonyl-PEG-acid has also been used as a linker for prodrugs, which can enhance the pharmacokinetic properties of drugs.