Chemistry in Pictures: Waterless reflux

Hollywood often indicates chemistry by shooting scenes of glass flasks filled with mysterious boiling liquids. But some stereotypes are true: reflux reactions are a common sight in synthetic labs. And when you don’t want the solvent to boil away, you need a condensing column to cool the vapors back into a liquid. The standard setup for that process uses a glass tube inside a glass jacket with cold water running through the jacket. But that can consume a ton of tap water when the reaction needs to run for a long time. At the American Chemical Society meeting this week in Denver, the lab equipment maker Asynt showed off a waterless reflux column. The scallops sculpted into the columns cause vapor currents that maximize heat transfer. As a result, the ambient air flowing around the room provides enough cooling to run reflux reactions for most common solvents. Asynt says that in a trial at the University of Liverpool, the chemistry department saved almost $40,000 in water costs in a single year by using the waterless reflux columns in two of its teaching labs.

Credit: Craig Bettenhausen/C&EN

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