Bismuth subnitrate (Bismuth(III) oxynitrate) is a bismuth(III) compound that bears significant medical uses (e.g., as an antidiarrheic agent). Bismuth subnitrate is a simple, readily available and effective catalyst for the Markovnikov-type hydration of terminal acetylenes[1].
[1]. SzÉcsÉnyi Z, et al. Bismuth Subnitrate-Catalyzed Markovnikov-Type Alkyne Hydrations under Batch and Continuous Flow Conditions. Molecules. 2021;26(10):2864. Published 2021 May 12.