Curated digital datasets of acid dissociation constants in dipolar aprotic solvents

The acid dissociation constant is a key thermodynamic property, but large compilations of highly trustworthy data in non-aqueous solvents are scarce. This work presents a new partial digitization of a compilation, with corrections, of pK _a data published originally by Kosuke Izutsu in 1990 as an official publication of the International Union of Pure and Applied Chemistry (IUPAC). The data span the six solvents nitromethane, N-methyl-2-pyrrolidone, dimethylacetamide, 4-methylpentan-2-one (or methyl isobutyl ketone), hexamethylphosphoramide, and sulfolane. Because the original data were not critically evaluated, we also include proposed systematic corrections to the data, which resolve major inconsistencies in the original data compilation. To contextualize this new dataset, we also present a numerical analysis of the recently-released IUPAC 2025 dataset for neutral acids in the solvents dimethyl sulfoxide, acetonitrile, dimethyl formamide, acetone, pyridine, tetrahydrofuran, and propylene carbonate, compiled by Leito and collaborators. We discuss the creation and contents of these digital data compilations, and analyze not only the pK _a values, but also the overall reliability, methodology, and other available metadata. The Izutsu dataset is available at: https://doi.org/10.5281/zenodo.19626584 and the IUPAC 2025 dataset at https://doi.org/10.5281/zenodo.12608876.