Abstract Convenient and efficient S-methylation of mercaptans or thiophenols occurs with dimethyl carbonate (DMC) in room temperature ionic liquids (RTILs)[Bmim] Cl.[Bmim] Cl can be recycled in four subsequent runs with only a gradual decrease in activity. A possible mechanism of this transformation is also discussed. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and ...