Time-dependent evolution of the relative gas-phase abundances of CH₂OHCHO, CH₃ OCHO, t-HCOOH, C₂H₅OH, CH₃ NH₂, CH₃ OCH₃, and C₂ H₅CN in the warm-up phase in evolving models. Fiducial model 2 adopts n_H = 2 × 10³ cm⁻³, A_V = 10, t_cold = 3 × 10⁵ yr, t_warmup= 2 × 10⁵ yr, T_max =200 K, G₀ = 10⁴, ζ_CR = 1.3 × 10⁻¹⁷ s⁻¹. Other evolving models adopt a different value of each of these parameters at a time. In panel L, a linear rather than a quadratic warm-up rate is used in Eq. (3) (n = 1).