Description

Tos-Peg21-Tos CAS NO 35164-96-6 is a high-purity, bifunctional polyethylene glycol (PEG) derivative featuring terminal tosylate (p-toluenesulfonate) groups. This compound is a critical intermediate for the synthesis of custom PEG linkers and spacers, enabling the controlled conjugation of molecules in pharmaceutical and biotech applications. It is essential for researchers and manufacturers in drug delivery, bioconjugation, and materials science who require precise, reproducible, and functionalized PEG building blocks.

Application

• Bioconjugation Linker: Serves as a versatile heterobifunctional crosslinker for attaching drugs, proteins, peptides, or fluorescent dyes.
• PEGylation Reagent: Used to synthesize custom PEG derivatives with specific terminal functionalities for modifying therapeutic proteins and peptides to enhance solubility, stability, and pharmacokinetics.
• Polymer Chemistry Intermediate: Acts as a macro-initiator or chain extender in the synthesis of block copolymers and functionalized polymeric materials.
• Surface Modification: Facilitates the grafting of PEG chains onto nanoparticles, quantum dots, or medical device surfaces to impart stealth properties and improve biocompatibility.
• Hydrogel Formation: Employed as a crosslinking agent in the creation of PEG-based hydrogels for tissue engineering and controlled release applications.
• Diagnostic Reagent Synthesis: Used in the preparation of contrast agents and other diagnostic tools where a hydrophilic PEG spacer is required.

Basic Information

Product Name	Tos-Peg21-Tos
CAS No.	35164-96-6
Molecular Formula	C48H82O25S2
Molecular Weight	1091.3 g/mol
Synonyms	α,ω-Bis(p-toluenesulfonate) poly(ethylene glycol) (n~21); PEG-1000 ditosylate; Poly(oxy-1,2-ethanediyl), α,ω-bis[(4-methylphenyl)sulfonyl]-; Polyethylene glycol 1000 ditosylate; Bis-Tos-PEG21; 1,1'-[1,2-ethanediylbis(oxy-21-oxo-3,6,9,12,15,18-hexaoxahenicosane-21,1-diyl)]bis[4-methylbenzenesulfonate]; Ditoluene-p-sulfonyl PEG 1000; PEG ditosylate (MW ~1000)
EINECS	Contact for details

Quality Control

Our Tos-Peg21-Tos is manufactured under strict quality management systems. Each batch undergoes rigorous analytical testing to ensure high purity and consistent performance. A comprehensive Certificate of Analysis (COA) is provided, detailing specifications for identity, purity, and functional group content. We support cGMP manufacturing for advanced pharmaceutical applications.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry place at 2-8°C or as indicated on the label. This product is hygroscopic (moisture-sensitive) and should be handled under anhydrous conditions to maintain stability and reactivity.

Specification

Item	Specification
Appearance	White to off-white waxy solid or viscous liquid
Identification (IR)	Conforms to structure
Assay (HPLC)	≥ 95.0%
PEG Average MW (n)	~21 (~1000 Da)
Water Content (KF)	≤ 1.0%
Residual Solvents (GC)	Meets ICH guidelines

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.