Thiyl radical

In chemistry, a thiyl radical has the formula RS, sometimes written RS^• to emphasize that they are free radicals. R is typically an alkyl or aryl substituent. Because S–H bonds are about 20% weaker than C–H bonds, thiyl radicals are relatively easily generated from thiols RSH. Thiyl radicals are intermediates in the thiol-ene reaction, which is the basis of some polymeric coatings and adhesives. They are generated by hydrogen-atom abstraction from thiols using initiators such as AIBN:

RN=NR → 2 R^• + N₂

R^• + R′SH → R′S^• + RH

Thiyl radicals are also invoked as intermediates in some biochemical reactions.