Tos-PEG4-acid

• CAT Number: I017004
• CAS Number: 1453117-42-4
• Molecular Formula: C16H24O8S
• Molecular Weight: 376.42
• Purity: ≥95%
• Synonyms: 3-[2-[2-[2-(4-methylphenyl)sulfonyloxyethoxy]ethoxy]ethoxy]propanoic acid
• InChI: InChI=1S/C16H24O8S/c1-14-2-4-15(5-3-14)25(19,20)24-13-12-23-11-10-22-9-8-21-7-6-16(17)18/h2-5H,6-13H2,1H3,(H,17,18)
• InChIKey: BAXYSSILQKCWFA-UHFFFAOYSA-N
• SMILES: CC1=CC=C(C=C1)S(=O)(=O)OCCOCCOCCOCCC(=O)O

Tos-PEG4-acid(CAT: I017004) is a heterobifunctional polyethylene glycol (PEG) linker featuring a tosyl (tosylate) leaving group at one end and a carboxylic acid at the other, connected by a four-unit PEG spacer. The tosyl group enables efficient nucleophilic substitution with thiols, amines, or alkoxides, while the terminal carboxyl group can be conjugated to amines via amide bond formation. The PEG4 backbone improves hydrophilicity, flexibility, and solubility, reducing steric hindrance in conjugation reactions. Tos-PEG4-acid is widely used in bioconjugation, PROTAC design, polymer chemistry, and drug delivery research, where orthogonal functionality and controlled linker length are required for precise molecular engineering.