Silica-supported sulfonic acid-functionalized ionic liquid coated with [bmim][PF6] as a scavenger for the synthesis of amides.

The methodology of using a silica gel-supported functionalized ionic liquid as a scavenger in the purification of parallel synthesis products was demonstrated. Silica-supported sulfonic acid-functional ionic liquid was synthesized by etherification, aminate, and quaternary aminate from activated silica gel and 3-chloropropyl trimethoxysilane, imidazole, and 1,4-butanesultone, which was followed by acidification using trifluoromethanesulfonic acid and anion exchange with potassium hexafluorophosphate. A conventional ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate was then used to coat the surface of the silica gel. The silica-supported functionalized ionic liquid was used as a scavenger in the removal of excess amine in the parallel synthesis of amides. Desired products were obtained in excellent yields and purity with a sequestration time of less than 100 min at room temperature. After scavenging, the scavenger was easily filtered out and regenerated.