Chemical model abundances for the warm-up stage of a hot-core type model with a final collapse density of n_H = 6 × 10¹⁰ cm⁻³ (high-density model, black lines for NH₂CN and green lines for NH₂CHO). Solid lines denote gas-phase molecules; dotted lines indicate the same species on the grains. The red lines correspond to the abundance profiles of gas-phase and grain-surface NH₂ CN for the lower density model, run at n_H = 1.6 × 10⁷ cm⁻³.