N-(Propargyl-PEG4)-N-bis(PEG4-acid) is a PEG-based PROTAC linker that can be used in the synthesis of PROTACs[1]. N-(Propargyl-PEG4)-N-bis(PEG4-acid) is a click chemistry reagent, it contains an Alkyne group and can undergo copper-catalyzed azide-alkyne cycloaddition (CuAAc) with molecules containing Azide groups.