Suggested grain-surface chemical routes for the formation of targeted C₃H₆O₂ isomers in the ISM. Dashed lines indicated processes involving more than one step. We highlight in boldface molecules identified toward G+0.693. C₃H₆O₂ species that were not detected and whose formation has not been tested experimentally by Wang et al. (2023) and Wang et al. (2024) are highlighted with a light purple box. For simplicity, stereoisomerism is not considered in this plot.