Abundances of H₂C₃O and H₂C₃S isomers as a function of time predicted by our models with n(H₂)=2×10⁴ cm⁻³. The horizontal rectangles represent the observed abundances of HCCCHO (Cernicharo et al. 2020b), c-H₂C₃O (Cernicharo et al. 2020b), l-H₂C₃O (this work), HCCCHS (Cernicharo et al. 2021c), c-H₂C₃S (Remijan et al. 2025), H₂C₃S (Cernicharo et al. 2021c). The vertical rectangle represents the chemical age given by minimizing the difference between the observations for TMC-1 and the model for 62 species (Wakelam et al. 2006).