2mercaptoethyl

2-Mercaptoethyl is an organosulfur substituent characterized by a two-carbon alkyl chain bearing a thiol group on the terminal carbon. Its structural representation is -CH2-CH2-SH, and when it is attached to a larger molecule it is typically linked through the first carbon, giving R-CH2-CH2-SH. The substituent’s formula is C2H5S.

The thiol group endows the moiety with nucleophilic character and the ability to engage in redox chemistry. The pKa of a typical thiol such as this is around 10.3–10.7, so at physiological pH a portion exists as the thiolate. Reactions include formation of disulfides (RS-CH2-CH2-SR) upon oxidation, and reaction with alkyl halides to form thioethers (R-S-CH2-CH2-SH). The group can also act as a soft-donor ligand, coordinating to various metal centers in coordination chemistry and materials science.

Applications and context: the 2-mercaptoethyl group serves as a flexible linker or functional handle in organic synthesis, bioconjugation, and surface or polymer functionalization. It is common in the design of thiol-containing linkers and is related to cysteamine (HS-CH2-CH2-NH2), a well-known biological molecule.

Safety: thiols typically have strong, often unpleasant odors and can be hazardous in concentrated forms. They should be handled with appropriate protective equipment and good ventilation.