Gravimetric and Thermal-Imaging Characterization of Water-Free Reflux Condensers for Laboratory Applications

Water-free reflux condensers, which use convective cooling from the surrounding air to condense vapors, avoid the need for cooling water, which is more sustainable than water-cooled condensers, and eliminates the risk of flooding, but these devices are newer and less familiar to many chemists, who may never have used them before. To facilitate the shift to water-free condensers, several types of water-free condensers (simple glass tube, Vigreux column, Condensyn, Findenser, and air-cooled Dimroth) were characterized using three different solvents (ethyl acetate, acetone, and tetrahydrofuran) under both gentle and vigorous refluxing conditions to compare their relative performance and determine the condensing capacity/failure point. In addition to experimentally quantifying the performance of each condenser both gravimetrically and via infrared thermal imaging, energy-balance models were developed to gain insight into which factors were most important in driving their performance. Several of the water-free condensers, including the Findenser, Condensyn, and air-cooled Dimroth condenser, were shown to provide suitable performance for most refluxing operations.