Toward Catalyst's "Fingerprint": A Rapid Quality Control Method of Catalysts for Heterogeneous Hydrogenation

The study addresses a significant problem in the reproducibility and standardization of hydrogenation catalysts. A fast and robust quality control (QC) method for Pd-based catalysts is proposed. The identity of the catalyst in the standard sample can be verified, and a general conclusion about its activity can be drawn by using the proposed method. The method is based on the hydrogenation of acylated imidazopyridine with gaseous hydrogen under mild conditions (1 atm, 40 °C) with no specialized equipment required. Monitoring is implemented using ¹⁹F or ¹H NMR and/or UV-vis spectroscopy, both of which are readily available in any modern laboratory. A model reaction, i.e., hydrogenation of acylated imidazopyridine, can yield three distinct products depending on the catalyst activity (under standardized conditions). The ratio of these products' content serves as a catalyst "fingerprint" for the QC. Using this method, a series of commercially available Pd-based catalysts was evaluated. The results clearly demonstrate the potential of this methodology as a reliable tool for robust testing of a wide range of catalysts for the heterogeneous hydrogenation of organic compounds as well as for QC in lab-scale or industrial synthesis of new batches of the latter.