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Drug Delivery

Linkers & Activators

PEGylation of lipids, liposomes or biomolecules often affords the activation of a functional group, e.g. the presentation of thiol groups for the reaction with MalPEG.

Sometimes this is done by the cleavage of disulfide bonds, sometimes by the 'conversion' of amino to thiol groups (see 2-Iminothiolane).

Special spacers are needed for controlled cleavage under physiological conditions or just for sterical reasons.

2-Iminothiolane Hydrochloride is commercially available in GMP quality and is commonly used in the PEGylation of therapeutic proteins.

For the transformation of a primary amine to a sulfhydryl group in drugs and therapeutic proteins.

For conjugation with monoclonal antibodies, proteins, peptides and herbicides.

As a hetero-bifunctional crosslinker for proteins with Dithionitrobenzoic acid (DTNB).

Immobilisation of colloidal particles with a sulfhydryl-maleimide bond.


  • Traut et al, Biochemistry, 12, (1973), 3266,
  • Alam et al., Indian J Exp. Biology, 40, (2002), 477.
  • Wang et al., J Nucl. Med., 33, (1992), 570.
  • Suwa et al., Anticancer Resear.,19, (1999), 4161.
  • Phaneuf et al., Biomaterials, 18,(1997), 755.
Chemical structure

MW  137.63
CAS No.: 4781-83-3

Product identification
  • 2-Iminothiolane Hydrochloride
  • Traut’s Reagent
  • 2(3H)-Thiophenimine, dihydro-, hydrochloride

Traut’s Reagent is a white to off-white, crystalline substance.

Solubility of 2-Iminothiolane Hydrochloride
  • Soluble in water (e.g. 1 g/ 1 ml at 20-22°C), methanol, ethanol, DMSO.
  • Low solubility in acetonitrile, ethyl acetate, DMF.
  • Insoluble in diethyl ether, methyl tert. butyl ether.
  • Traut et al, Biochemistry, 12, (1973), 3266
  • King et al., Biochemistry, 17, (1978), 1499
Key Specifications


white to off-white powder without foreign matter 
Assay (Chloride): 98-104%
Assay (HPLC): 98.0 to 102.0% calculated on anhydrous and solvent free basis
Purity (HPLC 208nm) Not lower than 98.0%area
Other specifications such as Bioburden, Endotoxin Content, Identification, Heavy Metals, Sulfated Ash, Related Substances and Residual Solvents on request.
Stability & Storage

The product is sensitive to moisture and has to be stored under dry conditions. The recommended storage condition is 2 - 8°C. To date no degradation under these storage conditions have been observed.


The material is packed in amber glass bottles or a polyethylene bag under inert atmosphere. The packaged material is put into an aluminum-polyethylene composite foil to protect it from humidity-


For full safety information, necessary precautions and proper handling, please refer to the respective Material Safety Data Sheet (MSDS).

© Merck KGaA, Darmstadt, Germany, 2014

All references to Merck refer to Merck KGaA, Darmstadt, Germany.


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