Playing with Fire? A Safe and Effective Deactivation of Raney Cobalt using Aqueous Sodium Nitrate

Sponge or skeletal metal catalysts (such as Raney-type hydrogenation catalysts) are ubiquitous and extensively used in large-scale industrial hydrogenation processes, including petrochemical refining, materials manufacturing, and even food chemistry. Despite the many advantages of these nonprecious metal catalysts, they are underutilized in smaller-batch organic synthesis, including pharmaceutical manufacturing processes, because of safety concerns. Here we describe a heretofore little known deactivation procedure using aqueous sodium nitrate that renders the spent catalyst safe to handle even when dry. During development of a chemoselective nitrile reduction using a sponge cobalt catalyst, we demonstrated that this procedure is much safer than other commonly employed oxidative or acidic quenching methods. This procedure should significantly improve the safety aspects of using these catalysts in myriad settings, from lab-scale synthesis to manufacturing processes for active pharmaceutical ingredients.