Crystalline coating tames rambunctious reagents

Chemistry has always been a smelly and potentially hazardous business. To safely handle useful but highly sensitive, toxic, and malodorous compounds, chemists have developed methods involving vacuum lines, glove boxes, and fume hoods. But those approaches can be costly and are often inconvenient to use. Researchers have thus come up with some clever work-arounds, such as encapsulating air- and moisture-sensitive reagents in paraffin capsules, protecting enzymes in cross-linked aggregates, and storing reactive metals in silica or alumina powders. But for organic reagents, a general-use crystalline material that acts as an inert delivery system has been missing. Alexander Schwenger, Wolfgang Frey, and Clemens Richert of the University of Stuttgart have now found one in the form of a bulkily substituted adamantane that creates inclusion compounds to tame rambunctious reagents such as benzoyl chloride, cyclohexyl isocyanide, and phosphorus trichloride (Angew. Chem. Int. Ed. 2016, DOI: 10.1002/anie.201605507). The researchers mix tetrakis(dimethoxyphenyl)adamantane (TDA) with the reagents to generate crystalline materials that mask the reactivity and odor of the reagents and make them easy to handle and dispense on the benchtop. When the crystal-coated materials are dissolved in an appropriate solvent, the reagents are able to react as normal, and TDA precipitates and can be recovered by filtration for reuse.