Anionic SO3H-functionalized ionic liquid: An efficient and recyclable catalyst for the Pechmann reaction of phenols with ethyl acetoacetate

This paper has reported an anionic SO3H-functionalized ionic liquid N-methylimidazolium sulfomethylsulfonate ([Hmim][HO3SCH2SO3]) for the synthesis of coumarins by Pechmann reaction. The [Hmim][HO3SCH2SO3] is easier to prepare by one-step neutralization reaction of N-methylimidazole with methanedisulfonic acid and show high catalytic performance for Pechmann reaction. Besides, the catalyst can simply be separated from the reaction mixture and recycled ten times without noticeable loss of activity. [GRAPHICS] .