Errors are similar for COSMO-RS calculations, which are discussed in the SI; the MAE for those classes above are 2.3 kcal mol -1 and 5.0 kcal mol -1 , suggesting that these high errors are potentially due to issues with the data or QM calculations rather than the machine learning model. It is unclear to the authors at the moment why exactly model performance is significantly worse for dicarboxylic acids compared to monocarboxylic acids, given that only dissociation of the first proton was considered, so that the acids essentially behaved as monoprotic acids.