Small-Scale Synthesis of Dibenzyl Ketone for the Organic Chemistry Teaching Laboratory

Due to safety concerns, a larger scale synthesis (0.5 mol) of dibenzyl ketone (1,3-diphenylpropanone, DBK) was performed for more than ten years as a class wide demonstration in the second-semester undergraduate organic chemistry teaching laboratories at the University of Texas at El Paso. This synthetic step was added to a seven-step convergent synthesis of hexaphenylbenzene found in Experimental Organic Chemistry: A Small-Scale Approach, 2nd ed. by Wilcox and Wilcox. Herein, we report a safer, small-scale (7 mmol) synthesis and purification of DBK which allows students to perform the experiment individually or in pairs. In addition, because the iron byproducts generated proved difficult to remove from used glassware, a cleaning protocol using concentrated black tea was also developed.