“…Bifunctional catalysis has recently been applied to the aforementioned class of synthesis using special molecules that possess both acid and base sitesalso known as zwitterionic buffering agents. ,− In this sense, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) is a zwitterionic buffering agent that consists of a piperazine backbone attached to two different ethyl groups containing a sulfonic acid group and a hydroxyl group at their ends, which impart unique properties to HEPES . Meanwhile, the sulfonic acid group is highly acidic and can donate protons.…”